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| ORIGINAL M4 C O UNITED STATES
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| ] NUCLEAR REGULATORY COMMISSION IN THE MATTER OF: DOCKET NO:
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| ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 320TH GENERAL MEETING O ~
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| LOCATION: WASHINGTON, D. C. PAGES: 1 - 195 DATE: FRIDAY, DECEMBER 12, 1986 rh""Jy.': .-
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| ~~
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| 3RDR OKt8Prenmr x
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| . . .~ .. ms om t -
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| 30 \odemove from ACRSTice ACE-FEDERAL REPORTERS, INC.
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| O''
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| d e \y OfficialReporters
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| '0\ 444 North Capitol Street Washington, D.C. 20001 8612170210 861212 (202) 347-3700 PDR ACRS
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| - T-1565 PDR NATIONWIDE COVERAGE
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| 1 1CR29207'1' DAV/dnw
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| ~'
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| (
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| 1 UNITED STATES OF AMERICA -
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| - V) 2- NUCLEAR REGULATORY COMMISSION 3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4 , , ,
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| 5 320TH GENERAL MEETING 6
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| 7 Nuclear Regulatory Commission Room 1046 8
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| 1717 H Street, N.W.
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| Washington, D. C.
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| 9 Friday, December 12, 1986 10 The 320th General Meeting convened at 8:49 a.m.-
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| 11 12 ACRS MEMBERS PRESENT:
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| f 13 MR. DAVID A. WARD, Chairman 14 MR. JESSE C. EBERSOLE MR. HAROLD ETHERINGTON 15 DR. MAX W. CARBON DR. WILLIAM KERR *-
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| 16 DR. HAROLD W. LEWIS g DR.-J. CARSON MARK MR. CARLYLE MICHELSON 18 DR.' .DADE W. MOELLER DR. DAVID OKRENT 19 MR. GLENN A. REED DR. FORREST J. REMICK 20 DR. PAUL G. SHEWMON DR. CHESTER P. SIESS 21 MR. CHARLES J. WYLIE 22
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| -23 24 25 ACE-FEDERAL REPORTERS, INC.
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| j 202-347 3700 Nationwide Coserage 800-3Me86
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| ..J
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| /--
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| . k_)3 PUBLIC NOTICE BY THE UNITED STATES NUCLEAR REGULATORY COMMISSIONERS' ADVISORY COMMITTEE ON REACTOR SAFEGUARDS l
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| FRIDAY, DECEMBER 12, 1986 The contents.of this stenographic transcript of the proceedings of the United States Nuclear Regulatory commission's Advisory Committee on Reactor Safeguards (ACRS), as reported herein, is an uncorrected record of the discussions recorded at the meeting held on the above date.
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| No member of the ACRS Staff and no participant at
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| -( ) this meeting accepts any responsibility for errors or inaccuracies of statement or data contained in this transcript.
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| 6 O
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| 2071 01 01 2 DAVbur 1 PROCEEDI NGS 2 MR. WARD: Let's go right into the next agenda 3 item. He are 15 minutes behind. We will have to open up 4 the meeting.
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| 5 Let's go ahead.
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| 6 (Slide.)
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| 7 MR. MICHAELS: My name is Ted Michaels, with the 8 Office of Nuclear Reactor Regulation, the Standardization 9 and Special Projects Branch Directorate.
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| 10 My talk this morning is on a policy statement 11 that we developed on deferred plants.
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| 12 (Slide.)
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| -m 13 Before I go into the policy statement, I would 14 like to go into some definitions so we clear the air on what 15 we mean by the different terminology we are using here.
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| 16 The deferred plant -- this is sort of a 17 chronology of when you go from a deferred to a canceled 18 plant.
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| 19 A deferred plant is a plant where the licensee 20 fully expects to reactivate the construction of the plant 21 but for one reason or another he has ceased his construction 22 or reduced it to a maintenance level and he maintains his 23 construction permit.
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| 24 A terminated plant is one whero the licersee does f ~' , 25 not plan to reactivate construction. So be has announced i
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| i ACE-FEDERAL REPORTERS, INC.
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| q 52071 01:02 3 1 thatl construction has been terminated, but his construction 7'{ DAVbur LJ ~
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| : 2. . permit is still in effect.and he may have requested for a 3 withdrawal of the construction permit but that construction 4 permit has not been withdrawn at that point in time.
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| 5 A canceled plant is a plant without a valid CP.
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| .6 Now, the policy statement talks about a deferred 7 plant and a terminated-plant. It does not talk about a 8 canceled plant.
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| 9 We do talk about a canceled plant in a staff-10 paper, which is Commission'SECY 86-359, and we talk about it 11 also -- we also have a list of tables, Table 2 and Enclosure
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| -12 4, which covers all canceled plants.
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| g- 13 (Slide.)
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| U 14 DR. MOELLER: You could quickly remind us how 15 many are.in each group.
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| 16 MR. MICHAELS: Yes, there are four deferred 17 plants, there are 12 terminated plants, and there are 26 18 canceled plants.
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| 19 Now, staff has developed a policy statement in 20 response to the following directives on the subject. The 21 details of these directives are in Enclosure 1 of the staff 22 paper.
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| 23 (Slide.)
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| 24 In order to address these directives, the staff p
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| a 25 task force, consisting of members of the Office of Nuclear ACE-FEDERAL REPORTERS, INC.
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| 202-347 3700 Nationwide Coserage 8m346646
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| 2071 101 03 4 DAVbur 1 Reactor Regulation, Inspection and Enforcement, the Office 2 of General Counsel, Research, and the regional offices was 3 formed to consider and develop the following areas.
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| 4 The first three -- maintenance, preservation, and-5 documentation requirements for deferred plants, 6 applicability of new regulatory staff positions for deferred 7 plants being reactivated, and procedures for reactivating 8 deferred plants -- are addressed in the policy statement 9 itself.
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| 10 The identification of regulatory improvements and 11 research initiatives is in Enclosure 3 of the staff paper, 12 and the population and status of deferred and terminated e' 13 plants is in Enclosure 4 of the paper.
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| xy
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| )
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| 14 (Slide.)
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| 15 The scope cf the study primarily centered around 16 def erred plants. The policy statement does not cover 17 canceled plarts because no owner of a canceled plant has 18 expressed any interest in a policy statement to deal with 19 deferred plants or canceled plants at this time.
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| 20 DR. REMICK: So if there was one, I assume you 21 would handle that on a case-by-case basis?
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| 22 MR. MICHAELS: That is right. We would handle it 23 on a case-by-case basis.
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| 24 DR. MOELLER: And terminated plants?
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| 25 MR. MICHAELS: No. Canceled plants, reactivation
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| (}
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| ACE-FEDERAL REPORTERS, INC.
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| 202-M7-37(o Nationwide Coserage foL33M6&6 i
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| p 2071 01 04 5 DAVbur 1 of canceled plants.
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| 2 DR. MOELLER: What about activation of a 3 terminated plant?
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| 4 MR. MICHAELS: A terminated plant. We say in the 5 last few pages of the policy statement that if a terminated 6 plant has any inkling that they might reactivate, that they 7 should follow the same procedures from the standpoint of 8 maintenance, preservation as a deferred plant.
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| 9 (Slide.)
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| 10 One of the more important aspects of the policy 11 statement is the identification, the regulations and guides 12 associated with maintenance, preservation, and 13 documentation. The applicable regulations and guides have 14 been identified in the policy statement.
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| 15 These requirements apply to plants under 16 construction as well as plants on deferred status.
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| 17 The licensee may choose to modify existing 18 commitments during extended construction delays by 19 developing a quality assurance plan that is commensurate 20 with the expected activities and length of delay.
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| 21 The licensee is expected to discuss with the 22 appropriate regional office and headquarters the expected 23 construction delay period and the quality assurance program 24 to be implemented during the deferral.
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| j 25 Modified quality assurance programs are inspected ACE-FEDERAL REPORTERS, INC.
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| 202-347 3700 Nationwide Cm erage MG 336-6M6
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| 2071 01 05 6 DAVbur 1 and reviewed in accordance with appropriate inspection 2 procedures.
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| 3 One of these procedures is review of quality 4 assurance for an extended construction delay, which is 5 Inspection Procedure 92050.
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| 6 (Slide.)
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| 7 Another important aspect of the deferred plant 8 policy is how new regulatory staff positions will be applied 9 to deferred plants when they are reactivated. The policy 10 statement says that plant specific backfits of new staff 11 positions will be considered in accordance with the backfit 12 rule, 10 CFR 5109, which requires that the staff justify
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| -)
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| 13 value impact analysis, any backfits after October 21st, 14 1985.
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| 15 DR. REMICK: Could you elaborate a little bit on 16 that, specifically what that sentence means?
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| 17 In other words, are you saying that the deferred 18 or terminated plants would be handled in the same way if 19 they were not deferred or terminated from the standpoint of 20 backfit?
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| 21 In other words, doesn't the backfit rule define 22 certain dates before which the backfit rule doesn't apply 23 and after which it does? '
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| 24 MR. MICH AELS : T, hat is right. The backfit rules
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| (~l v
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| 25 applies to plants -- the backfit has a lot of cut-in times.
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-370) NationnIde C0%erage 80 L 336-(M6
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| ( .
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| 2071 01-06 7 M DAVbur 1 ILthink one of_the cut-in times, if your 3
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| -e
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| '~'
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| 2 construction permit 'is af ter October 21st, 1985, then 3 backfits'after that point in time have to be -- you have to 4 have a value impact analysis developed by the staff.
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| 5 If your construction permit came in before 6 October 21st, 1985, it would be based on when you got your 7 OL docketed, six months before the time you got your OL 8 docketed.
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| 9 DR. REMICK: That is the same as if you were 10 continuing along with construction; am I correct?
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| 11 MR. MICHAELS: That is correct. A deferred 12 plant, in a sense, would have the same protection as an es 13 operating plant.
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| L) 14 That is the issue. That is what the industry is 15 concerned about, that they will not come back for, say, two 16 or three years from now and be required to implement a lot 17 of backfits without a value impact analysis.
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| 18 DR. REMICK: So they are protected, but they also 19 have the same requirements?
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| 20 MR. MICHAELS: That is right. They are 21 protected, but they have the same requirements.
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| 22 DR. OKRENT: Suppose a plant is deferred for a l 23 dozen years under this proposed policy.
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| j 24 Does the staff see any difference?
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| {} 25 MR. MICHAELS: No. We don't see any difference I
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| ACE-FEDERAL REPORTERS, INC.
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| X 347 37(n) Nationwide Coverage *Mk3346M6
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| 2071 01 07 8 3 DAVbur 1 because the plant would be preserved. If it was an 2 operating plant, it would still have to go through the same 3 backfit analysis, and if the design was judged adequate at 4 one point in time we don't see any difference.
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| 5 Any new designs would have to be, if they were 6 promulgated on an operating plant, they should have the same 7 action for a deferred plant.
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| 8 MR. HERNAN: This is Ron Hernan, for the Staff.
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| 9 Correct me if I am wrong, but for each CP there 10 is a defined termination date or expiration date. Does that 11 CP renewal process now apply to these deferred plants?
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| 12 MR. MICHAELS: Yes, it does.
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| <3 13 MR. HERNAN: In other words, I don't know of any V case where we have approved a CP for a 12-year period.
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| 14 15 DR. OKRENT: But they could ask for a renewal?
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| 16 MR. HERNAN: Yes, they could, but the staff has 17 to go through evaluations of their reason for delays in each 18 case.
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| 19 DR. OKRENT: Yes.
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| 20 MR. HERNAN: There is a control at that point.
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| 21 DR. OKRENT: It is a control of completely 22 different things than what we are talking about when we talk 23 about backfits, however.
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| 24 Why does the staff think -- let me postulate a
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| (^T 25 situation. A plant is 50 percent done and then is delayed
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| \~)
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-37W NJtlOnwlM CMCTJgC #U 334NM
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| I 2071 01 08 9
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| /].DAVbur 1 for'10 years.
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| .O 2 Why should backfit considerations be identical as
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| : 3. if that plant had been completed on time and started 4 running?
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| 5 MR. MICHAELS: Because if the plant was licensed 6 at one point in time and let's say 10 years elapsed, any 7 backfits would have had to have the backfit rule applied.
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| 8 Now, we consider this plant -- the design has 9 been approved at one point in time by having the OL 10 docketed, in a sense, not completely approved but in any 11 case it has been accepted, and any further plant specific 12 backfits would be applied by the backfit rules.
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| fg 13 -DR. OKRENT: What does it really mean technically Q for an OL to be docketed and accepted?
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| 14 15 MR. MICII AELS: It has been accepted. It has had 16 an adequate submission. The FSAR.
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| 17 DR. OKRENT: It has not been reviewed?
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| 18 MR. MICil AELS : No, it has not been reviewed.
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| 19 DR. OKRENT: Suppose you had a plant that didn't 20 even have its OL docketed. Would that be different?
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| 21 MR. MICil AE LS : Yes, that would be different. If 22 the plant did not have its OL docketed, then if a 23 construction permit was before October 21st, 1985, we can 24 impose backfits without any backfit analysis.
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| l
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| {} 25 DR. OKRENT: Do we have any of these plants that ACE-FEDERAL REPORTERS, INC.
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| 202 Nationwidc Cmetage M133MM6
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| ,.,,_-m..-... - -m__. . _- , _ _ _ . .
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| . . _ ._ , _ _- 147 3 700
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| 2071 01 09' 10 A g - DAVbu r 1 don't have an OL docketed?
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| ,f
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| %) 2 MR. 'MICHAELS: All the deferred plants have 3 docketed OLs.
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| 4 DR. OKRENT: So we are talking then about plants 5 to which you see the backfit rule' apply?
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| 6 MR. MICHAELS: Right. .
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| I 7- DR. OKRENT: Even if they are deferred literally 8 an indefinite time, no cutoff?
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| 9 MR. MICHAELS: That is correct in an abstract 10 sense, but in a practical sense we are going to be looking 11 at it maybe on a case-by-case basis.
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| 12 DR. OKRENT: And you don't perceive that there is 13 some difference -- either in the ease with which 14 modifications can be made to a plant that is deferred for 10
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| ; 15 years -- you don't see any possibility that it may be more 16 appropriate to make them in a plant that is being deferred 17 for an extended time compared to a plant that is operating?
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| 18 MR. MICHAELS: No, I don't.
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| 19 DR. OKRENT: You treat them the same in your 20 mind?
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| ; 21 MR. MICHAELS: That is correct, because the value i
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| 22 impact analysis and the final analysis will show whether a 23 backfit is necessary or not.
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| : 24 It depends on the stage of completion of the
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| {} 25 plant. If the plant -- if something has to be backfitted i ACE-FEDERAL REPORTERS, INC.
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| :o2.m., x.m _ u ,c _ ... -
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| I 2071_01 10 -
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| _ 11 f's DAVbur 1- in an area where it is not completed, then the value impact O 2 analysis _will'show that that backfit is needed, in case, you 3 'know, there is an issue where backfit is concerned._
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| 4 DR. OKRENT: So you would do plant specific 5- backfits; is that what you are saying? Generic backfits 6 don't really take that into account?
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| 7 MR. MICHAELS: I was going to come to that,.but 8 generic backfits -- when an issue is resolved from a generic 9 standpoint and it is applied to a particular class of 10 plants, then it would apply to that particular class of i
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| 11 plant and would have to be implemented.
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| 12 DR. OKRENT: Recently -- I am probably missing
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| ,g 13 something, but my impression is most of the generic backfits V 14 involved changing of tech specs or an operating procedure or 15 training of someone.
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| : 16. MR. MICHAELS: If that was the case and it 17 applied to that particular class of plant, it would be put 18 onto that plant and the generic backfit analysis would cover 19 that plant, also.
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| 20 DR. REMICK: For example, if it were decided that 21 this class of plant should have filtered vents on 22 containments, this plant would be subject to that class of 23 plants?
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| 24 MR. MICHAELS: That is correct.
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| 25 DR. OKRENT: But the decision might be made, (o~T ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage NXk33MM6
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| 2071.01 11 12 1 thinking about plants that were in operation, whereas you 7') DAVbur wJ
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| -2 have here a plant that may be 10. years from operation, and I 3 don't'know-.thatnin the examination of the generic question D4 'this group will'be carried along as a group to be thought of 5 on its.own. 'I.can't tell from what I have read that that 6 .would be the case.
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| 4 7 MR. MICHAELS: That is the way we are planning to 8 consider it.
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| 9 DR. OKRENT: You are planning to consider what?
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| 10 MR. MICHAELS: A' deferred plant is a plant that 11 is similar to a plant that is under construction.
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| 12 DR. OKRENT: I thought you said it-is similar to
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| .n 13 a plant --
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| i A.,_)
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| 14 MR. MICHAELS: It would also be -- it is an 15 operating plant, also.
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| 16 DR. OKRENT: It'is hard for me to see how it is.
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| 17 the same as one and the other both.
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| 18 But why don't you go on?
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| 19 MR. HERNAN: It is treated primarily as a plant 20 that is under construction, Dr. Okrent. The only thing that 21 is different is the rate of construction is much slower and 22 can be zero.
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| 23 We did have quite a few plants that were delayed 24 after the TMI accident, and we had to go through an
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| (~T 25 evaluation on these plants of which backfit should be
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| ) (m)
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| ACE-FEDERAL REPORTERS, INC.
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| 202 347 3700 Nationwide Coverage 80tul6-(M6
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| - , . - - , - - , . . . - ~ . . . ~ - . , . . , - - -
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| ;2071.01 12 .13 F [ DAVbur' l' applied.
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| ~
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| 2 MR. MICHAELS: I guess I covered this area,
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| ~
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| 3 ' generic backfits, and also~ provisions of other policy 4 statements applicable to plants under construction will be 5 implemented.
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| 6- That'is, for instance, in the severe accident 7 policy statement -- that is NUREG-1070 -- it refers to an 8 integrated systematic approach to examine each nuclear power 9 plant now operating or under construction for possible risk 10 contributors that might be plant specific.
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| 11 Deferred plants will have to perform this plant 12 specific vulnerability analysis. However, the backfit rule 13 will be'used to decide which identified plant 14 vulnerabilities need to be implemented.
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| 15- MR. ETHERINGTON: Is there a step chango in NRC 16 surveillance between deferred and terminated plants?
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| 17 MR. MICHAELS: Usually, a deferred plant goes 18 through lesser inspection requirements than an operating 19 plant or a plant under construction. This is done 20 semiannually by the region.
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| 21 MR. ETHERINGTON: Then another change in when it 22 is terminated?
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| 23 MR. MICHAELS: When it is terminated, it still 24 has to be inspected until the withdrawal of the construction 25 permit.
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| ACE-FEDERAL REPORTERS, INC.
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| 202 347-370) Nationwide roserage im31W4
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| L2071 01 l3 14
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| (' DAVbur 1 MR. ETHERINGTON: On the same level as merely u.)
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| 2 ~ deferred?
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| 3 MR. MICHAELS: Probably.
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| 4 MR. HERNAN: I'think the answer to your question 5 is no. Terminated and deferred, the same standards and 6 inspection frequencies would apply.
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| 7 The biggest difference is the applicant has 8 expressed a different intention as far as ultimately 9 completing the plant.
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| 10 MR. MICHELSON: I thought he had maintained a 11 different level of quality controls.
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| 12 MR. HERNAN: Between deferred and terminated? I 13 don't believe so.
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| O 14 MR. MICHELSON: The terminated plant still has 15 full OA control?
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| 16 MR. HERNAN: The terminated plant still has an 17 active construction permit.
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| 18 The big step change comes when the plant becomes 19 canceled. At that point the construction permit is no 20 longer valid, and the controls go away.
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| 21 DR. OKRENT: Is there any requirement on the 22 level of engineering staff that a plant should be maintained 23 in a deferred state?
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| e 24 MR. MICil AELS : There is no requirement, but we 25 heard yesterday at a meeting -- and this is for WPP3-1 --
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| ACE-FEDERAL REPORTERS, INC.
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| mm ., - _ u m _ ,. ., s u-
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| h f 2071 01 14 15 l
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| [ DAVbur 1 there were about 50 man-years expended on the maintenance
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| ~
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| > 2 and preservation of WPPS-1.
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| 3 DR. OKRENT: Let's say a plant like that is 4 deferred for five or 10 years. During that period, for 5 example, INPO comes out with a set of recommendations for 6 things that should be done in plants of that type, but they 7 are not going to have the engineers who understand that 8 aspect necessarily, since they have engineers who are 9 interested in keeping things from rusting, and so forth.
| |
| 10 How does the staff know 10 years later whether 11 these or other similar kinds of recommendations are even 12 known, let alone acted on?
| |
| rs 13 MR. MICHAELS: Before they come in for
| |
| (.v )
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| 14 reactivation, they have to list all the outstanding generic 15 issues that have been promulgated on that plant and all 16 other outstanding action items.
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| l 17 18 19 20 21 22 23 24
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| /^)
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| V 25 ACE-FEDERAL REPORTERS, INC.
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| x.m ., m_m c~. -
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| e 2071 02 01 16 DAvbw 1 DR. OKRENT: It is not my impression that INPO 2 recommendations are generic issues or action items.
| |
| 3 MR. MICHAELS: Well, those will have to be 4 reviewed.
| |
| 5 DR. OKRENT: I don't see anything in what I read 6 that -- can you point me to the page that tells me how to 7 know or I&E information notices? I don't know that they 8 have to even have road I&E information notices durin that 9 period.
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| 10 MR. HERNAN: INPO initiatives are, of course, 11 voluntary on the part of the utility. As you state, 12 information notices do not require a response from the 13 utility, so wo do not have a control on either of those.
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| 14 DR. OKRENT: llow about things where you put out 15 -- I don't know what you call it -- but where you ask for 16 the utility to respond. If it is a deferred plant, do they 17 have to respond?
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| 18 MR. IIERN AN : Yes. Any bulletins and engincoring 19 letters, we require a response from the utility.
| |
| 20 DR. OKRENT: But they might say, we haven't 21 gotton to the part of the instruction where this is a 22 i relevant item. Let's say it is a question about something 23 l in the control room, and they haven't reached that yet.
| |
| l 24 j So that will bo their answer.
| |
| ~N 25 MR. IIERN AN : That will still have to be carried l
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| ACE-FEDERAL REPORTERS, INC.
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| w: w n,, s,-nac c..-,nc m a u,-,
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| l 2071'02-02 17
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| [k DAVbw 1 as a commitment, as if they were actively constructing _the
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| (_) 2 plant.
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| 3 It will be part of the overall review.
| |
| 4 DR. OKRENT: So if the NRC had a formal request, 5 they would still have to, at some point respond?
| |
| 6 MR. HERNAN: Yes, they would.
| |
| 7 DR. OKRENT: But all'these other things, you just 8 don't know what they would do and whether they would even 9 know about this industry experience or recommendations, and 10 so forth.
| |
| 11 MR..HERNAN: That is correct. Our experience has 12 been that the engineering staff is dictated by the extent 13 of the preservation program; however, I think our experience 14 -- and correct me, if I am wrong, Ted -- also indicates that 15 they do keep a cadre of licensing people actively on the 16 project during that point in time to maintain a liaison and 17 to maintain the construction permit in terms of 18 regulations.
| |
| 19 MR. MICHE LSON: They are housekeeping, though.
| |
| 20 They are keeping things in order, that is all.
| |
| 21 MR. HCRNAN: It depends on the project and the 22 activity of the licensing activies to that class of plants.
| |
| 23 DR. OKRENT: You know, there have been 24 situations where vendors have set up notices which some l 25 licensees said you never even saw. Is Salem a good example?
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| }
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| ACE-FEDERAL REPORTERS, INC.
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| 3- m., m _ m o ,...,. ._
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| 2071 02 03 18 DAVbw 1 Over 10 years, there may be many of these.
| |
| 2 How is this kind of thing going to be 3 ascertained? You know, that you know, if and when this 4 thing comes in for a real OL, that a host of things which 5 are nontrivial in their effect on safety, whether the Staff 6 has made it a formal request or not, have been dealt with or 7 even known about.
| |
| 8 MR. HERNAN: Again, I guess I would have to say, 9 we would operate probably in the same manner as we did after 10 TMI, and that is, that there was a certain amount of 11 catch-up, in terms of what has happened, in terms of new 12 regulations. I am not sure about vendor regulations, how 13 closely we track those, but there had to be a conscious 14 effort in those plants that will reactivate after TMI on 15 where were we at the time we stopped and what has transpired 16 since that point in time, and what is needed to complete our 17 operating license review.
| |
| 18 Each of these projects does have an advantage of 19 following that in those cases.
| |
| 20 MR. MICHELSON: At the point in time a utility 21 desires to start a project back up, he obviously has to hae 22 a whole lot of people. You just can't sustain that kind of 23 a force. Does the NRC go back and reexamine the competency 24 of the utility to start that project back up? That is where t'~j 25 you will look to see, have they got the right kind of people ACE-FEDERAL REPORTERS, INC.
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| mum s_ ,& c_, se m-
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| :(
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| ;2071?O2'04J 19 -
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| .P 1 'now to back.'and do.all-this catch-up and whatever.
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| -!g] DAVbw
| |
| '2 Is'that a part of the requirement, that the.NRQ-
| |
| -3 :dofa competency review?
| |
| 4 MR. MICHAELS: Yes. Their procedures for '
| |
| 5- reactivating are stated in the policy statement.
| |
| '6 MR. MICHELSON: Is that included? I didn't 7 : recall seeing that kind of a statement in there.
| |
| 8 MR. MICHAELS: Yes, it is in there. rl 9 MR. MICHELSON: That is where you would ask these '
| |
| 10 kind of questions, and you would not let them reactivate 11 until such time as they had the kind of people with the 12 capability and the ability to go back and play catch-up.
| |
| 13 MR. HERNAN: I think you have to distinguish O 14 between actual reactivation and construction, which is the 15 utility's option, and our progression with the operating.
| |
| 16 license review. Two different things.
| |
| 17 MR. MICHAELS: Here it is. Under Item 3(a)(6).
| |
| 18 DR. OKRENT: Could you read?
| |
| 19 MR. MICHAELS: It says:
| |
| 20 "Information to be submitted by 21 licensee when reactivating."
| |
| 22 Now in response to this question, it says:
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| 23 "A description of the management and 24 organization responsible for construction 25 of the plant."
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| * ACE-FEDERAL REPORTERS, INC. !
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| 202-347 3700 Nationwide Coverage 800 336 (644
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| L2071!02 05' 20 il yA /DAVbd DR. OKRENT: That is a very general answer.
| |
| jy v ,
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| ?S <.' 3 .x
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| [2' MR. MICHAELS: Let me read it. It saus"
| |
| , '$ . ? r.
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| 4* 'E 3 '"A listing of any regulatory requirements
| |
| ( r
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| , 4 applicable to the plant that have
| |
| .5 become effective since the plant x.- 6 6 construction was deferred, together
| |
| ; 7 with a description of licensee's
| |
| , 8 proposed plans for compliance with 9 these requirements."
| |
| 10 DR. OKRENT: Well, again, you are obviously going 11 to want to see anything that is an NRC rule or regulation or
| |
| '; 12 some other requirement met, otherwise somebody could, I yq A-13 ' suppose, say you are being illegal or whatever for not 14 meeting your own regulations, but there are other things e,
| |
| i h 15 that are important for safety, as well.
| |
| S d 16 MR. MICHELSON: The other thing, basically, the I 17 crux of it is the ability to self-regulate. You are trying a
| |
| 18 to move more and more of the self-regulation back to the Ji9 licensee.
| |
| ,- 20 Now what has been visibility or what is even a 21- requirement that he self-regulate himself during this 22 interim period?
| |
| 'O '
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| 23 Well, the answer, I think is no. lie just has to i '
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| 24 maintain his records, but he doesn't have to pick up on
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| [] 25 things INPO suggests doing, and so forth.
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| U
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| > l ACE-FEDERAL REPORTERS, INC.
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| , 202 Ntionside Ometage W)h6M6
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| , , . - ~. ._ . - . - . . _ , . . . ._ ., _ _ . _ _ ,
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| | |
| 2071 02 06 21' r'3 DAVbw 1 DR. REMICK: But a active li7ensee does not.
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| '._/
| |
| 2 MR. MICHELSON: But we are doing it, to some 3 extent, right now, on an informal basis. We are looking at 4- what the licensee is doing, in terms of implementing INPO 5 requirements, implementing vendor requirements, and so 6 forth. We are doing it now. And they aren't NRC 7 requirements, but in this case, I assume we don't need a 8 monitor, or there is no requirement, I guess to monitor the 9 self-regulation aspects.
| |
| 10 DR. REMICK: Self-regulation, I think, is the 11 important term. The best they could do is to self-manage, 12 not regulate themselves.
| |
| f- 13 MR. MICHELSON: The idea was to turn the D( 14 regulation back to the licensee. Self-management is fine.'
| |
| +
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| 15 DR. REMICKt Don't turn the regulation back.
| |
| 16 DR. MOELLER: Is there no plan on the part of the 17 NRC Staff, when a deferred plcnt is reactivated, to go'back 18 and look at the same things that they have done on a' regular 19 plant, meaning if they-look at INPO?
| |
| 20 DR. MARK: There is certainly a plan to go back 21 and treat it as de novo, unless it was a very specific 22 thing.
| |
| 23 DR. REMICK: And there is a list of 24 specifications. If you are going to reactivate, an advance
| |
| /~T 25 notice of 120 days, and so forth. That type of thing. I l.s ,
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| ACE-FEDERAL REPORTERS, INC. ,
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| 202-347-3700 NatbnwLfe Coserage 800-33M(46
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| ., .r _ _ - ~ . -
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| 2071 02 07 22
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| , " - ) - DAVbw
| |
| , 1 interpret it to mean it would be a typical OL review.
| |
| ~
| |
| 2 MR. MICHAELS: Yes, it would be the initiation of 3 an OL review, essentially reviewing where the application 4 stood at what point in time and taking it from there.
| |
| 5 (Slide.)
| |
| 6 The next Vugraph deals with the proposed 7 regulatory improvements. During the development of the 8 policy statement, the task force was requested to identify 9 any areas where the regulatory framework could be improved.
| |
| 10 We found that the present regulations are not sufficiently n v
| |
| " j' 11 prescriptive with regard to withdrawal of a CP. For 12 example, nothing is said in the present regulations on what
| |
| /
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| g- 13, happens if the licensee requires a plant to be terminated Q;
| |
| 14 and a construction permit expires-before the NRC can process 15 the cancellation.
| |
| 16 The policy statement addresses this uncertainty i
| |
| 17 by requesting the licensee to provide notice to the Staff d 18 sufficiently far in advance of the expiration of the CP to 19 permit the Staf f to detert '.ne appropriate terms and
| |
| ~0 !
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| 20 conditions.
| |
| . 21 It also says that prior to formal cancellation of
| |
| : 1' 22 the permit by the Commission, the permit holder is expected O
| |
| 23 to comply with the Commission's rulings, including taking 24 affirmative steps to extend construction permits which may 25 expire before Commission action and the termination request
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| (~}-
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| .u ACE-FEDERAL REPORTERS, INC.
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| 202 347-3700 Nationwide Coserage 80lb336-646
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| 2071 02 08 23 f y DAVbw I can be completed. However, even though the policy addresses
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| ()
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| 2 this uncertainty, the regulations may have to be revised to 3 provide more specificity in this area.
| |
| 4 We may need some more internal NRC guidance on 5 specific information needed for termination of a CP. For 6 instance, what are the criteria for site stabilization and 7 other aspects of site termination?
| |
| 8 We also may need detailed guidance for inspection 9 of deferred plants prior to reactivation.
| |
| 10 (Slide.)
| |
| 11 We have coordinated this with the industry, and 12 we have met with the AIF on February 19, 1986, and requested es 13 their views on whether a policy statement for deferred and t
| |
| N.)<
| |
| 14 cancelled plants was necessary.
| |
| 15 The AIF provided a letter March 31, 1986, on 16 reactivation of construction projects. They agreed that a 17 policy statement was necessary, that the policy statemenmt 18 should apply to plants with construction permits, that the 19 plants with withdrawn construction permits should be handled 20 on a case-by-case basis, that the backfit rule should be 21 ruled to implement new requirements in effect for plants 22 with construction permits and that the current preservation 23 requirements were adequate, as long as records are i 24 maintained.
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| t l
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| (~)
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| %/
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| 25 The review and comments on our final draft were l
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage MG3h M
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| 2071 02 09 24 DAVbw I submitted to us on July 2, 1986.
| |
| 2 (Slide.)
| |
| 3 In summary, this policy does not have any new 4 safety requirements, and there are no new safety issues that 5 have been addressed. It essentially consolidates existing 6 requirements and focuses on the requirements for deferral 7 and reactivation of deferred plants.
| |
| 8 It also clarifies how the backfit rule will be 9 applied when a deferred plant is reactivated.
| |
| 10 It has been coordinated with the industry, 11 through the AIF and additional coordination will be 12 forthcoming, since the policy statement will be issued for
| |
| ~
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| 13 public comment.
| |
| 'wi 14 DR. REMICK: Does this do anything really new, 15 other than what you are doing, just indicating to people 16 what the current status is of these plants or how you are 17 handing the plants, what they must do for reactivation?
| |
| 18 MR. MICHAELS: Yes.
| |
| 19 DR. REMICK: So there is no change in the policy 20 or regulations?
| |
| 21 MR. MICH AE LS : That is correct. There is no 22 change in policy or regulation.
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| 23- MR. HERNAN: This reflects the experience we have 24 had with those plants that fall in those categories.
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| /~') 25 MR. WYLIE: Could I conclude from this that L.J ACE-FEDERAL REPORTERS, INC.
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| 202-347 3700 Nationwide Cmerage 8M336-6M6
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| 2071 02 10 25 DAVbw 1 when reactivating the plant, that the Staff would do a 2 complete review of the construction organization and all the 3 other programs to reaffirm their accuracy and that there 4 would be a thorough and complete inspection of all equipment 5 which had been installed prior to putting the plant on hold, 6 is the main thing during that deferral period, to assure 7 that it had not deteriorated during that period?
| |
| 8 MR. MICHAELS: Ther is a semiannual inspection 9 performed by the regions.
| |
| 10 MR. WYLIE: Of everything?
| |
| 11 MR. MICHAELS: The whole preservation and 12 maintenance program.
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| ,s -
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| 13 MR. WYLIE: A lot of equipment is dependent on O 14 the state of the plant when it was placed on hold. There is 15 a lot of equipment put into the plants that may be exposed 16 to weather and changing conditions.
| |
| 17 Now I know they will say, okay, you preserve 18 that, but over long periods of time, unless you disassemble 19 that equipment and lacok at it, you don't know what 20 condition it is.
| |
| 21 MR. MICHAELS: There are criteria for inspecting 22 that equipment.
| |
| 23 MR. WYLIE: That is what I am saying.
| |
| 24 Can you conclude from this policy that it will be
| |
| (''T 25 thoroughly inspected, disassembled, if necessary, and looked V
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| ACE-FEDERAL REPORTERS, INC.
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| 2071 02 11 26 l l
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| DAVbw I at?
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| 2 MR. MICHAELS: The policy doesn't address that 3 specifically, but the procedures are there. Deferred plants 4 have been reactivated. Limerick has been reactivated. So 5 the deferred plants have been reactivated.
| |
| 6 MR. WYLIE: I am saying that, but we are talking 7 about plants that have been deferred for long periods of 8 time.
| |
| 9 MR. MICHAELS: As I said, there are maintenance 10 and preservation programs in effect. The purpose of these 11 preservation programs is to assure that the equipment is 12 properly maintained, and I am sure that they have started 13 procedures when they come back on to determine whether the
| |
| ~
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| 14 equipment can be operational.
| |
| 15 MR. WYLIE: Okay.
| |
| 16 My question, basically, was, could I conclude 17 that that would be done, that everything would be inspected, 18 to the extent of determining anything that had deteriorated 19 during the referral period?
| |
| 20 MR. MICHAELS: I would say the ongoing 21 maintenance and preservation program is as an assurance of 22 that, in addition to start-up procedures that the licensee 23 would have to conduct before preoperational testing would 24 assure that.
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| 25 MR. EBERSOLE: A question.
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| ACE-FEDERAL REPORTERS, INC.
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| '2071 02 12 27
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| ,/','DAVbw 1 A case in point would be the long-term storage of 2 carbon steel pipe, you know, miles of it, sitting there, 3- maybe with full water. The stuff grows rust like you 4 wouldn't believe. Or a case in point, what do they do to 5 clean this gunk out? Do they take on explicit 6 investigations? You can't flush it out. What do they do?.
| |
| 7 Do they hot store it? Do they put anticorrision inhibiters 8 in it?
| |
| 9 MR. MICHAELS: They put desiccants in it. I am 10 not familiar with that particular area, but they do have
| |
| .11 anticorrosion protection and desiccants, inert atmospheres, 12 when necessary.
| |
| 4
| |
| -f~s 13 MR. EBERSOLE: I know, even for one-year storage, b 14 it remains static during shutdowns, and that is a problem, 15 as far as inerted water.
| |
| 16 MR. MICHAELS: I don't have anybody here from 17 Inspection and Enforcement to answer that question at this 18 point, but I am sure, you know, as I said, they have 19 determined that the present maintenance and preservation 20 requirments, the quality assurance program that is in place, 21 is adequate, if looked at and approved by the regional 22 offices at headquarters.
| |
| 23 DR. REMICK: Dave, this is your subcommittee, and 24 I only acted on your behalf, ran the subcommittee the other
| |
| /~T 25 day, but a couple of comments I would like to make.
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| ! (/
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| ACE-FEDERAL REPORTERS, 'NC.
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| 202-347-3700 Nationwide Coverage W , rite
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| 2071 02 13 28 DAVbw 1 We determined that Staff still mandated a 2 proposed policy statment to go out for public comment.
| |
| 3 At the subcommittee meeting, of all those present 4 at that time, the recommendation was that they didn't see a 5 need for a letter at this time.
| |
| 6 DR. OKRENT: I understand that is the case. I 7 have a differing view, and there is a draft, possible 8 letter, and I have been adding a couple of sentences as I 9 listened to what Wylie and Michelson were asking about. And 10 so I will put a draft letter on the table Saturday morning, 11 and the committee can do what it wants with it.
| |
| 12 DR. REMICK: Did you have anything else?
| |
| 13 DR. OKRENT: I don't have any more.
| |
| 14 DR. REMICK: Mr. Chairman, I suggest, unless 15 there are other questions, we are finished with this topic.
| |
| 16 MR. WARD: Very good. Thank you, Ted.
| |
| 17 Let's take a 15-minute break.
| |
| 18 (Recess.)
| |
| 19 20 21 22 23 24
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| (''N 25 v
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| '2071 03 01 29 f' DAV/bc 1 DR. OKRENT: If I recall correctly, in November,
| |
| . (,)
| |
| 2 the committee had some consideration of the implications of
| |
| '3 Chernobyl. And in prior meetings, we've heard something 4 about what was known about the details of the accident 5 itself.
| |
| 6 The subject today is ACRS comments on the 7 implications of the accident at Chernobyl. On this subject, 8 there was a subcommittee meeting held Novem!:er 5, 1986, and 9 one again Wednesd'ay of this week, which I couldn't attend.
| |
| 10 And Forrest Remick chaired.
| |
| 11- I'll ask him to add any comments that he wishes.
| |
| 12 At the time of the November 5th meeting, the staff had a 13 draft document. Something was mailed out before the J
| |
| -)
| |
| 14 December subcommittee meeting. I'm not sure if what we have
| |
| -15 now is not only the complete document and it's in the book?
| |
| 16 MR. SAVIO: Yes.
| |
| 17 DR. OKRENT: There is a yellow draft of a 18 possible ACRS letter on the implications, which includes 19 some, but not all, comments provided by members to drafts 20 one and two.
| |
| 21 But, in any event, it presents for the benefit of 22 the committee members at least one possible approach that 23 the committee could take in responding to what is, I think, 24 a formal request to comment; the Commissiners themselves
| |
| {} 25 wanted to hear what the ACRS has to say on this.
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| ACE-FEDERAL REPORTERS, INC.
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| 2071 03 02 30 r '' , DAV/bc 1 'So there is an agenda which shows that we run i l
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| ~'
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| 2 from 10:45 'til 12:45, according to what I have here -- is 3 that correct? -- which includes a half hour presentation by 4~ the staff, a half hour discussion with the staff. I mean, 5 there's an hour there. Maybe it will be an hour 6 presentation on that point.
| |
| 7 And then time for some general discussion.
| |
| 8- I think, if members want to see points available 9 for possible inclusion in the letter, which will be 10 considered in the material tomorrow morning, I think it 11 would be very valuable for them to advise me during this 12 general discussion period, so I can try to draft something g- 13 up to meet their wishes.
| |
| V) 14 We normally drop things out quickly, but 15 generating new paragraphs takes somewhat more time. In any 16 event, let me leave my aspect of the report as such.
| |
| 17 I recommend that you do look at the yellow draft 18 while the staff is giving their presentation. Let me ask 19 Forrest Remick first, and then other subcommittee members 20 for any comments.
| |
| 21 DR. REMICK: The things that I would add is, 22 originally, the staff had thought they would be going to the 23 Commission this month with this. It's our understanding now 24 that they're waiting for the fact-finding report to be
| |
| (')
| |
| v 25 issued, the other report. So they probably now will not be ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage 804336-6M6
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| .2071'03 03 31
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| , DAV/bc 1 going this: month.
| |
| L,[
| |
| 2 So the urgency of getting the letter out this 3 month is not there, although we can still do it. And I 4 think we should.
| |
| 5 But it has slipped a little bit. The other is 6 there's a fair amount of material and it took a good half 7 day in the subcommittee meeting, so we suggested to the 8 staff that, rather than having a number of presenters, that 9 perhaps one person should give a summary, realizing that he 10 is going to need backup from other staff experts.
| |
| 11 So, Brian Sharon, with the understanding of the 12 fact that he won't be able to perhaps answer all the
| |
| ,3 13. detailed questions, but will have backup people, but-in the U '14 interest of saving time, we've asked him to give an 15 overview, paying particular attention to not only the 16 overview but any changes since the subcommittee last saw the 17 reports -- either additions or modifications.
| |
| 18 Those are the guidelines we gave the staff in the 19 subcommittee meeting.
| |
| 20 DR. OKRENT: Any other comments by subcommittee 21 members, or questions?
| |
| 22 DR. MOELLER: I have some questions that I'll try 23 to bring up as we go along.
| |
| 24 DR. OKRENT: If not, let's proceed with the 25 staff.
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| ~}
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationside Coverage 800-336-6M6
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| i .
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| 2071 03 04 32 DAV/bc 1 (Slide.)
| |
| 2 MR. SHARON: My name is Brian Sharon, with the 3 NRC Staff, the Division of Safety Review and Oversight.
| |
| 4 I will be going through more or less an update of 5 the implications report. I'll try and stress primarily the 6 areas that have changed since the last presentation rather 7 than go through the whole thing again.
| |
| 8 I will rehash all of our conclusions, or 9 assessment and our conclusions in each of the areas. If you 10 have any questions, hopefully, we have the staff here that 11 was responsible for preparing the various sections. And if 12 I can't answer the questions, hopefully, they'll be able 13 to.
| |
| 14 Let me start out first by talking about the 15 status of our factfinding report. You just heard that the 16 Commission presentation on the implications report was 17 postponed because of the need to get this factfinding report 18 out first and on the street.
| |
| 19 Just as a reminder, the report was prepared prior 20 to the Vienna meeting last August, and it was primarily to 21 aid the delegation going over there in becoming familiar 22 with the RBMK reactor. And basically the Soviet power 23 system and the Soviet philosophy as best we can understand 24 it.
| |
| ~
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| 25 Basically, we dredged out all the available
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| (.)
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| ACE-FEDERAL REPORTERS, INC. ~
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| r l
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| ;2071 03 05 33
| |
| 'DAV/bc .1 literature that we could on.their reactors and safety 2 philosophy, et cetera, and tried to compile it.
| |
| 3 .The report did serve its purpose. It was very 4 helpful in preparing for the meeting. We went over there 5 .probably knowing as much about their reactors as one could 6 expect.
| |
| 7 We were surprised also, if you remember, that the 8 Soviets were very forthcoming at the Vienna meeting. They
| |
| ~
| |
| 9 gave us a very indepth understanding of their reactor and 10 the accident itself. They gave us a rather large report on 11 the' accident as well as their design.
| |
| 12 Subsequent to that meeting, the INSAG, the sc 13 International Nuclear Safety Advisory Group, which advises
| |
| .u-]
| |
| 14 Hans Blicks, Director General of IAEA, prepared a report on 15 the meeting.
| |
| 16 This report has now been completed. INSAG 75-1 17 is, I believe, the number of the report. We can get you a 18 copy if you don't have one.
| |
| 19 This also contained a good deal of faction 20 information about the accident and the reactor as well as 21 recommendations made to IAEA.
| |
| 22 The bottom line is that there is really no new 23 information that has been received since the Vienna 24 meeting. The Soviets have not provided any more 25 information.
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| ~}
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| ACE-FEDERAL REPORTERS, INC.
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| :2071'03'06' 34 l
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| f[^{LDAV/bc- 1; All indications are_they'probably won't. They U
| |
| 2- 'would most likely like this. thing to be put behind and
| |
| ~3- forgotten.
| |
| 4 _( Slide.)
| |
| 5 .This is just a quick' reminder of the content'of 6 the factual report.- 'There are nine chapters.- As you can
| |
| '7 see, NRC-lis responsible for the-introduction, the: summary, 8 the accident scenario andothe disbursion and transport of 9 .the fission products.
| |
| : 10. .We've had a n' umber of meetings on this with 11 various: authors. We had the draft chapters submitted last 12 month. We put.them together into a draft report. We g3' ~13 reissued it to the participants and then told the review !
| |
| M 14' meeting on November 18th. That meeting, hopefully, was to 15 ' finalize the report so we could publish'it.
| |
| 16 There were a number of comments and concerns 17 primarilry from DOE, and they had a number of concerns also 18 primarily with the FEMA and EPA writeups.
| |
| ! 19 We agreed that DOE should go off and resolve j 20 their concerns with FEMA and EPA. We were not mediators in
| |
| .; 21 this report. This is not a report where everybody has a 22 vote. And if there's a one that they vote on, it doesn't go 23 out.
| |
| p 24 Each agency would most likely write a report on ,
| |
| q 25 the implications to their agency. They would also have to
| |
| ~
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| ACE-FEDERAL REPORTERS, INC.
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| 4 202-347-3700 Nationwide Coverage 804336-6M6 r . . - . . . ~ . . - _ . . . ~,._._._.,___ _ ____ --
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| | |
| 2071403?07' 35 SyJDAV/bd 1 look at the, facts as'they related to their agency. .And L;e]J 2 rather-than have four or five different agencies in the 3 government issuing factual reports in their area, we decided
| |
| ~
| |
| : 4. it would make more sense for the government to issue one 5 report.
| |
| 6 The only thing we wanted to make sure'that these 7 participants understood is that everybody doesn't have a
| |
| ~
| |
| 8 veto in this.
| |
| 9 My understanding right now is that DOE has not 10 met with either FEMA or EPA. The FEMA meeting was scheduled 11 once and.then cancelled. And they have not done anything to ,
| |
| 12 meet with EPA.
| |
| T w 13 -We're assuming that either their concerns were 14 . resolved or they just weren't in substance, that they wanted ,
| |
| 15 toJpursue it. There is another meeting scheduled for the 16 19th, a week f rom today, which is designed to finalize the 17 factual report and go ahead and issue it.
| |
| 18 That meeting will be' attended by Mr. Vaughan from 19 DOE and Mr. Denton from NRC to make sure we all understand 20 that the object is to finish it.
| |
| 21 So we will hope that following the meeting on the 22 19th, we will probably just have some minor cleanup and 23 editorial things to get rid of, and then we'll have the 24 report available.
| |
| {) 25 (Slide.)
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage 800-33MM6
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| | |
| s 2071 03 08 36 DAV/bc 1 With respect to the implications assessment, let 2 me preface it by saying that the Commission briefing on the 3 implications was indeed postponed by Mr. Stello. He wanted 4 to have the factual report completed before he went down and 5 told the Commission about the implications.
| |
| 6 The Commission meeting has been rescheduled 7 tentatively for the week of January the 19th. So, in 8 keeping with Dr. Remick's point that he made about a letter, 9 we would probably need one no later than I would guess by 10 the 16th of January.
| |
| 11 That's the latest. That gives us one week in 12 which we can reflect any comments into the Commission 13 briefing. Obviously, if we had it earlier, that would be 14 very helpful because we could factor it in that much easier.
| |
| 15 Let me go through very quickly the implications 16 assessment report. Just recall that our approach was, 17 first, we wanted to identify the candidate issues that we 18 saw coming from Chernobyl. We wanted to assess them by 19 looking at (a) what was the current regulatory practice that 20 the NRC was following? And, then (b) when we did the 21 assessment, how did that relate to the regulatory practice?
| |
| 22 Was regulatory practice adequate? Was it not adequate? Did 23 it need to be strengthened in some areas, or what?
| |
| 24 From that, we then drew our conclusions as to 25 what actions may or may not be needed. I would point out it
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| (~]
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage 800-336-fM6
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| 2071 03 09 37 7
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| -Ag DAV/bc- .1 .w as tough but we tried not to get ourselves in the post-N-)^
| |
| 2- TMI type of mentality or anything that ever bothered us
| |
| '3 'about: nuclear power we shoveled into this report and said 4 this is an implication of it.
| |
| 5 -We were very careful that the issues that we 6 indeed put down are directly related to Chernobyl. And it 7 was not really something that we were.using as a vehicle to 8 bring to the surface an ongoing concern.
| |
| 9 For example, there are a lot of regulatory areas 10 where perhaps some people thought progress was not going as 11 well as it should or the staff should be doing more in those 12 areas.
| |
| 13 These concerns were already raised and
| |
| (~)
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| %/
| |
| -14 available. .In other words, people knew about them. And 15 while we look at Chernobyl and say that, yes, it certainly 16 has some relation there, it does not make this a new issue.
| |
| 17 In other words, the issue was already there. So 18 we shied away from those and we just tried to stay with 19 those that came directly from the Chernobyl accident.
| |
| 20 The report itself is not that extensive. It's 21 not much over a hundred pages. And there's a summary in 22 it. Each of the issues is assessed in the report, again 23 highlighting what the issue was, why it's an issue, why we 24 think it's an issue, what the current regulatory practice is 25 and our assessment of whether we need to do anything and, if (J~1 ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage 800 336-6646
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| 2071 03 10 38
| |
| ,- % DAV/bc 1 we do, on what schedule?
| |
| 3
| |
| ( l-2- DR. REMICK: Brian, I did not make the
| |
| ~3 subcommitte but I like that format of having, you know, what 4 is our current practice and what's the ongoing work. I
| |
| .5 thought that was very a logical format.
| |
| 6 MR. SHARON: We felt that it presents it in a 7 very clear way so you can easily see what the relationship 8 is.
| |
| 9 (Slide.)
| |
| 10 These are the list of issues. Let me point out 11 right now for you what changes have been made since the last 12 time you saw this.
| |
| j, q 13 First off is that we have-done a general updating v
| |
| 14 of these issues. We've improved them. We've made 15 modifications to the rewrite. For example, the reactivity 16 accident section was rewritten based on some comments we go 17 to provide a little more clarity and background as to 18 current NRC practices.
| |
| 19 So there was an overall just cleanup and updating 20 of the report. The operations section did have some changes 21 made. This was primarily to reflect the ACRS comments we 22 received last month. However, it was not a radical change 23 but more or less just to accommodate all the comments.
| |
| 24 There is one new section, 1.7 Accident 25 Management, which discusses the operator procedures, and so
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| (~)T
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| \_
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| 202-347-3700 Nationwide Cmerage 800-33MM6
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| ~2071 03 11 39
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| .gN .DAV/bc 1 forth, and their relationship to severe accidents.
| |
| %-)
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| 2 MR. EBERSOLE: Brian, in 1.4, is aux feedwater 3 now considered an engineered safety feature?
| |
| 4 MR. SHARON: Auxilliary feedwater? Yes, sir.
| |
| 5 Under item Roman II Design, not very much changed 6 here. On multiple unit protection, the last time we spoke 7 with you, I think we had pointed out there was one area we-8 were concerned about. And that is that multiple units, an 9 undamaged unit, in order to shut it down, operators had to 10 leave the control room.
| |
| 11 The question was: Is that -- well, fine, if the 12 undamaged unit are protected when they're in the control es 13 room because of control room design features, is there a
| |
| ( )
| |
| U 14 concern about operators leaving the control room and going 15 out into the plant? Is there a radiation hazard or 16 othe rwise?
| |
| 17 We first said we'll look at that because we 18 didn't know. We've done some additional assessment. The 19 conclusion was that we really don't see that there is any 20 hazard from the standpoint of being able to shut down and 21 keep an undamaged unit shut down.
| |
| 22 We can discuss that a little further later.
| |
| 23 Roman IV Emergency Planning. This section was 24 rewritten to be consistent with comments we received. It 25 also was rewritten just to be more consistent with the way
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| }
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| ACE FEDERAL REPORTERS, INC.
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| 2071 03-12 40
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| ;/3 DAV/bc 1 it was presente'd last month at-the committee meetings.
| |
| :V-2 The basic conclusions aren't really changed, but 3 the writeup-is a better reflection of the what the staff had 4 told you.
| |
| 5 And, then, last, we have a new section, Roman VI,
| |
| . 6 which is Graphite Moderated Reactors. This is primarily the 7 Fort St. Vrain assessment.
| |
| 8 What did we' learn from Chernobyl and how does it 9 -affect Fort St. Vrain?
| |
| 10 We'l1~be telling you about t h a ti . -
| |
| 11 12 fs 13 14 15 16 17 18 19 20 21 22 23 24 O '
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage 80lk33MM6
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| - . . - . . . - - . _ _ . . , - . , . - . . , _ . - ~. _, , , , . _ - . . , . - , . . -- _ _ , _ _ - . . - .
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| .=.
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| 2071 04 01 41 g N DAVbur 1 (Slide.)
| |
| ' Q.,)
| |
| 2 Let me walk you through the overall conclusions.
| |
| 3 You have seen this before. It is the same slide I believe 4 we used'last month.
| |
| 5 One is, and I think foremost, that there are no 6 fimmediate regulatory actions needed. Our assessment shows 7 that there is nothing that would prompt the staff or the 8 Commission to take some immediate action by means of an 9 order or bulletin or the like, or a 5054(f) letter.
| |
| 10 Our conclusion is that U.S. reactors are 11 protected against Chernobyl-like events, primarily by the 12 nature of their nuclear design. We don't have the positive 13 void coefficient. We have the fast acting shutdown systems b-- 14 with sufficient shutdown margin. We have a containment 15 around our reactors, and we have taken a hard look at the 16 human action safeguards, and we have concluded that we think 17 we have done a pretty adequate job of assuring that the 18 human actions would not result in the gross negligence, I 19 guess, that the Soviets had with their operators in causing 20 that accident.
| |
| 21 Number two, we would take the Chernobyl 22 experience into account in reinforcing some of the aspects 23 of requirements already existing or being developed; in 24 other words, stuff that is ongoing would certainly benefit
| |
| /~3 25 by taking into account what we learned from Chernobyl.
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| v ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage 800-336-6M6
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| .2071 04 02 42 g>f DAVbur 1 'These are in the area of human action controls, L.f 2 emergency planning, and containment performance.
| |
| 3 The third conclusion is that there are some areas 4 where we think some further study or research is probably 5 warranted. This is not to say that there is a definite 6 problem here, but we want to make sure that there is not.
| |
| 7 Some areas here are like the reactivity 8 accidents. We will explain this a little further, that 9 there are some accidents that we want to take a look at to 10 make sure that they are indeed low probability or precluded 11 by the design.
| |
| , 12 Accidents at low power, shutdown, there are
| |
| ,S 13 questions about the adequacy of the tech specs under those '
| |
| \_)
| |
| 14 conditions.
| |
| 15 And then source term characteristics. We want to 16 make sure Chernobyl is factored into the source term 17 research.
| |
| 18 And then lastly -- and I think this is true not 19 just of Chernobyl but of every event that happens, even like 20 Surry -- we need to take into account all of these events i
| |
| 21 that have occurred as a background, as a general background, t
| |
| 22 as we go about our regulatory duties and making sure that we 23 take them into account when we formulate rules, regulations, 24 or make decisions on safety.
| |
| {} 25 These are the general conclusions. I would now ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationside Coserage NB334&W
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| 2071 04 03 43 DAVbur 1 propose to walk through the specific areas in each of the 2 six main chapters.
| |
| 3 (Slide.)
| |
| 4 The first area is the operations. I think our 5 general conclusions here are that we have taken a hard look 6 at the administrative controls that we have in our 7 regulatory process, and we think they are generally adequate 8 to assure that there is a safe operating envelope for the 9 plants.
| |
| 10 This is not to say they are perfect. This is not i
| |
| 11 to say they can't be improved. But we looked at them, and 12 we say there is nothing here that says we need to either go 13 out and fix everything immediately or shut the plants down 14 until we do.
| |
| 15 We looked at the procedural adequacy and 16 compliance with regard to approving tests and unusual 17 operations towards bypassing safety systems, engineered 18 safety feature availability, and we also tried to take a 19 look at a very elusive subject -- operator attitude toward 20 safety and basic general safety philosophy.
| |
| 21 This is an area we discussed at the subcommittee, 22 and I think we don't really want to call it operator 23 attitudes towards safety. I think it is more just plant 24 personnel attitudes towards safety, which can be expanded to
| |
| ~'
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| 25 the utility's attitude towards safety, and someone suggested ACE-FEDERAL REPORTERS, INC.
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| m1.m x.m_ m c- s- -
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| l
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| 2071 04 04 44 DAVbur 1 how about the NRC, too?
| |
| 2 But I think we have taken a look and we think 3 that the attitudes that prevailed at Chernobyl, as the 4 Soviets told us, would not and could not exist over in this 5 country without being caught somewhere in the management 6 chain and stopped, so that the type of violations that 7 occurred there would not take place here.
| |
| 8 The last one in management systems - this is 9 accident management, and I will get into this one a little 10 later -- deals with the severe accident area.
| |
| 11 Some of the things we came up with under 12 operations was we think it might be worthwhile to consider a 13 high level onsite nuclear safety manager with no other 14 duties. This is a person who has some authority in the 15 plant, but his primary purpose is to make sure the plant is 16 running safely. He doesn't have any other duties.
| |
| 17 I think the word is " ombudsman" that was used, 18 although I think there is a question on that definition 19 whether that is appropriate.
| |
| 20 But we think this might be a very useful thing to 21 have in a plant, one person who is -- I won't call him the 22 person responsible for safety, but he is the person 23 responsible for overseeing and making sure that the plant is 24 operating safely and things are not being done to the plant f' ' 25 for the sake of expediency or perhaps just production.
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| ACE-FEDERAL REPORTERS, INC.
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| 2071u04:05- 45
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| .1 MR. EBERSOLE:- Why isn't the function fulfilled
| |
| .f*)zDAVbur'
| |
| \/ ,
| |
| 2 by thisiso-called adviser? -Is he not high enough in the
| |
| '3_ : organizational ladder?
| |
| 4 MR. SHARON: Wh'at?' The-shift technical adviser?
| |
| 5 The shift technical adviser I think perf orms some 15 of that function, but again.their role is-really as an 7 ady'iser to the operators. -They are not in the position 8 where they are stepping back and looking at safety from a 9 global aspect at the plant.
| |
| 10 DR. SIESS: He only functions after the 11 accident'.
| |
| 12 MR. SHARON: Sam, I don't know if you want to add
| |
| .- 13 anything.
| |
| 14- MR. WRIGHT:
| |
| Sam Wright, NRC.
| |
| 15 The-shift technical adviser is of course onsite, 16 and he responds to the situation when something goes awry.
| |
| 17 He-is not the one that looks over procedures, planned
| |
| -18 actions, and that sort of thing.
| |
| 19 We are looking really at a high level safety type i.- 20 who will do those kinds of functions.
| |
| 21 DR. SHEWMON: We added one guy to fix the one 22 that happened before. Now we are going to add another guy l 23 to fix the last one that happened.
| |
| 24 MR. SHARON: I think what we said is we think it i
| |
| {} 25 should be considered. We are not adding anyone yet.
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347 37tM) Nationwide Coverage 800 336-6M6
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| y 2071 04 06 46
| |
| .[^g.DAVbur 1 Obviously, there's drawbacks, just what you
| |
| :Cl 2 said. Every time something happens we can't add another 3 person, but there may be some merit to having such a person 4 there.
| |
| 5 .This is not a person that maybe is going to be 6 sitting and overseeing the operators.
| |
| 7 DR. SHEWMON: There is an Onsite Safety Review 8 Committee which was supposed to accomplish this in at least 5F DOE-operated reactors and I would think on the commercial 10 ones, also.
| |
| 11- MR. SHARON: There is usually a plant safety 12 committee.
| |
| ,S 13 DR. SHEWMON: Don't they review procedures for
| |
| .h 14 tests that haven't been done before?
| |
| 15- MR. SHARON: Yes, that is their job.
| |
| 16 Sam wants to add something.
| |
| 17 MR. WRIGHT: I just want to add that he has 18 competing duties. All these people who sit on that 19 committee have competing duties -- production activities, 20 maintenance, and that sort of thing, independence and 21 oversight.
| |
| 22 DR. KERR: You can't be completely independent of 23 the plant operations because if you are you won't know what 24 is going on.
| |
| {} 25 The plant is there to operate and operate
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| . ACE-FEDERAL REPORTERS, INC.
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| 2071 04 07' 47
| |
| ,e ~( DAVbur 1 safely.
| |
| ~
| |
| 2 If I see someone who is involved in safety and 3 who is also intimately involved in operation, I would say 4 they would have to know what it is going on, and it bothers 5 me to separate the safety from the operation.
| |
| 6 It seems to me the plant management has to be 7 responsible for safety. Otherwise it doesn't get looked 8 at. If you think someone else is responsible for safety and 9 he is only responsible for production, then you have in a 10 sense what may exist in some cases in the NRC versus the 11 operators.
| |
| 12 There are some operators who say, well, if we
| |
| , 13 satisfy all the NRC regulations everything is okay. You
| |
| . Q, g 14 could have one that says, well, if this guy doesn't tell us 15 to stop it will be okay.
| |
| 16 MR. WRIGHT: I understand what you are saying, 17 and I believe those are the kinds of' things we have to 18 consider. It is not clean in every regard, but we believe 19 that it warrants an examination.
| |
| 20 DR. CARBON: Is this like the J apanese concept?
| |
| 21 MR. WRIGHT: I am not really familiar with the -
| |
| 22 Japanese concept.
| |
| 23 MR. WARD: I would just like to endorse the 24 general thrust of what Bill says. Separation between safety
| |
| < 25 questions and nonsafety questions isn't always obvious.
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| b.~T ACE-FEDERAL REPORTERS, INC.
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| 202-347 3700 Nationwide Coserage an336-6M6
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| J2071'04 08L 48
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| ~
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| ('sf DAVbur 1 -
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| ILthink this-high level person, whoever, or-V 2 . organization or something needs to be involved in the L
| |
| c 3 overall operations so that he or she or it is in a position v
| |
| 4 to. recognize a safety issue even if it hasn't'been 5 identified by someone else.
| |
| 6 MR. MICHELSON: -The only problem, of course,'is 7 sorting out the difference between being involved and being 8 . responsible for. If you are responsible for production, 9 .then you might be a little clouded in terms of your thinking 10 on safety. If you are responsible for safety, then you
| |
| ~l1 perhaps are a little clouded on production.
| |
| 12 The two together have to work. They can't be one f3 13 and.the'same person, tj 14 DR. KERR There has to be a plant manager that 15 is responsible for managing the plant, and hence I can't see y
| |
| 16 giving some guy who tells the plant manager to shut the t
| |
| , 17 plant down, it is unsafe, and the manager thinks it l' 18 : continues.to operate.
| |
| 19 'MR. MICHELSON: That is where his thinking is 20 being clouded by his production responsibility, though.
| |
| 21 -That is the argument you get into.
| |
| 22 DR. CARBON: I would urge you to check the 1 ',
| |
| -4 k 1 23 Japanese system.- They do exactly what you are considering 3'';
| |
| 24 here. It would probably be of considerable help in finding 25 out what their experience has been.
| |
| (
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| '. 's
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| + .
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| y ' b s,
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| a ACE-FEDERAL REPORTERS, INC.
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| .t 2071 04 09 ' 49
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| .r"(;DAVbur 1 DR. REMICK: The Japanese, of course, throughout
| |
| :; )-
| |
| v' 2 their. history they have a mechanical engineer and an 3 electrical engineer -- and I can't think of 'the formal name, 4 but it is a person, basically by their utility law, that 5 .they must designate as kind of a professional engine'er in 6 that category, and they have added the engineering cNtegoryi 7 to that. <
| |
| .8 In one of my trips there,:. talking to the MITI 9 people, they did not necessarily recommend that concept for 10 U.S.. consideration, but they do have a long history of 11 having a mechanical engineer identitled, an electrical 12 engineer identified, and now a nuclear engineer, a chief
| |
| - 13 nuclear engineer.
| |
| ~
| |
| 14 DR. CARBON: One of those people -- I assume it 15 is the nuclear engineer -- has this authority to shut down 16 the plant if he feels it is being operated unsafely. Not 17 only does he have the authority, apparently he will lose his
| |
| .18 license or be penalized if he doesn't take action if-these 19 kinds of events are occurring -- not an accident,i but 20 operating unsafely. He is liable to t iose his license.
| |
| 21 They have one in each plant.
| |
| 22 DR. REMICK: Not on every shift, though.
| |
| t 23 DR. CARBON: No, not on every shift.
| |
| 24 MR. SHARON: One analogy -- I bring up two points 25 -- one analogy might be similar to a OA organization.
| |
| )
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| ACE-FEDERAL REPORTERS, INC.
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| 202 347-3700 Natkm side Coserage 80433M6m
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| ;:v.iC['
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| .2071104;-10 50 y;n-
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| ,:.Se fi :DAVbur r r
| |
| -1 Again, that is sort of a separate organization n' A _ ,7 1: 2 that provides to some extent an oversight function and does N
| |
| :L report directly to a high level manager.
| |
| 4 The analogy may not be perfect, but I think it is o
| |
| ct= '5 similar.
| |
| 11 n '
| |
| '6- DR. REMICK: Not all of us would like to see you 7 - follow the QA example.
| |
| 8 MR. SHARON: Keeping in mind that this is 9 strictly a recommendation to take a further look at 10 something, what we did is, okay, what went wrong at 9 11 Chernobyl?
| |
| 12 Obviously, these operators were'able to compound e- , 13 the problem by each one agreeing or somehow not seeing that L); .
| |
| g 14- '
| |
| safety systems were being bypassed and stuff. They went on 15 allowing it.
| |
| 16 We asked ourselves the question: is there 17 something that should be done or could be done in Y 18 U.S. plants that might prevent this from happening?
| |
| i 19 .One could say, well, obviously, if I had 10 20 safety people there that oversaw every aspect, that might be 21 one way.
| |
| 22 We also said, what about if we had one person?
| |
| 23 What we didn't have is we didn't have any clear 24 information that said this is no good or this is good. So
| |
| ~
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| 25 we couldn't dismiss it. We couldn't say, well, obviously,
| |
| {}
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| ACE-FEDERAL REPORTERS, INC.
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| 2 202-347-37tu Nanonwide t ourage 8(D3346646
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| l L2071 04 11- 51
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| .:>'y
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| ~ DAVbu r - 1 we don't want to have the safety czar there because we don't-
| |
| ]
| |
| 2 have-the-information together yet that could dismiss it.
| |
| '3 It: may. not be- right, it may be wrong, okay? But 4- we don't have the information today to dismiss it, So we 5 need to study.it more and see.if it makes sense.
| |
| 6 That is all we are really saying right.now, is we 7 want to study this more and see if it makes' sense.
| |
| 8 Obviously, if we come up with a conclusion that says 9 ultimately it makes sense, we will be back down here talking
| |
| '10 to you.
| |
| 11 MR. EBERSOLE: Brian, I think you might have a 12' look at the FAA's rule. They say if you have got two good 13 men up front that is enough. That might be better than half W)
| |
| %J 14 a dozen. I am not sure.
| |
| 15 MR. SHARON: That is certainly a factor we would 16 want to take into account when we take a look at this.
| |
| 17 MR. ETHERINGTON: If you ran exactly the same 18 tests as were run at Chernobyl in the U.S. plants, would you 19 have a runaway?
| |
| 20 MR. SHARON: No, because we would presume we 21 would not be bypassing, for example, all those protection 22 systems.
| |
| 4 23 MR. ETHERINGTON: Well --
| |
| 24 MR. SHARON: Chernobyl would not have happened 25 had the operators left the safety systems intact and not l
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| .{ }
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| l l
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| ! ACE-FEDERAL REPORTERS, INC.
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| ; 202-347-3700 Nationwide Coverage 800-3366M6
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| .- --, . _ . . , . . _ _ , _ . _ , _ . _ , . . . _ . . . _ - _ _ . . _ . . . . . - . . ~ . . - . . - _ . . _ , _ _ . . . _ _ _ . . _ . - . . _ . . , ,
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| 2071 04 12 . 52 DAVbur 1 bypassed them. The plant would have automatically shut down 2 long before they ever got to that condition.
| |
| 3 Had they bypassed everything but the last scram, 4 which was the reactor trip on turbine trip, we don't think 5 the accident would have happened.
| |
| 6 MR. ETHERINGTON: Let me say, suppose you bypass 7 all of the safety systems on a U.S. plant. Would you have a 8 runaway?
| |
| 9 MR. SHARON: It depends on what accident. If you 10 are saying, is there a way that I can, for example, withdraw 11 enough control rods to make it go prompt critical?
| |
| 12 MR. ETHERINGTON: Exactly the same experiment.
| |
| 13 MR. SHARON: I don't think it would.
| |
| 14 MR. ETHERINGTON: That is what I thought. Isn't 15 that po, int worth making for the benefit of the public, 16 anyway?
| |
| 17 MR. SHARON: I think we could certainly consider 18 it in the writeup. I tt'7k ta tried to capture that in 19 Chapter 2.
| |
| 20 MR. EBERSOLE: I don't think that is true in the 21 case of a boiler. We proclaim loudly, you know, we don't 22 have that, but we don't say that we operate under boiler 23 conditions. If you intercept the safety systems on a 24 boiler, you are going to be in trouble.
| |
| / 25 DR. REMICK: But that is not a positive void ACE-FEDERAL REPORTERS, INC.
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| 21)2-347-37(X) N3tlOn%1Je Caserage A n33W*m
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| 2071104 13 53
| |
| , ^s DAVbur 1 coefficient. It is a positive insertion of reactivity upon i
| |
| x-2 the collapse of the void. That is not anything surprising.
| |
| 3 MR. EBERSOLE: That can produce'some spectacular 4 consequences.
| |
| 5 MR. SHARON: You are saying we can induce an ATWS 6 in the plant?
| |
| 7 That is basically what it is. The answer is 8 yes.
| |
| 9 MR. EBERSOLE: He.said that I think you can 10 intercept the scram system on a boiler.-
| |
| 11 DR. KERd: His question was if you ran exactly 12 the same tests on a U.S. reactor would you have a problem?
| |
| 13 The answer is, no, you wouldn't.
| |
| -)
| |
| : s. /
| |
| 14 DR. OKRENT: It is impossible to run exactly the 15 same experiments because we don't have exactly the same 16 reactor.
| |
| 17 MR..EBERSOLE: If you disable the trip system.
| |
| 18 MR. ETHERINGTON: I wonder why you say that, 19 Dave. The experiment was to test the output from the 20 generator during rundown.
| |
| 21 DR. OKRENT: But if you look at the configuration 22 of the feedwater system and the recirculation pumps, you 23 know -- I don't know what the words "same experiment" means, 24 but if you mean in detail, we can't do that experiment.
| |
| (~T 25 MR. ETHERINGTON: The point is they had almost an l_
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| V i
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| ACE-FEDERAL REPORTERS, INC.
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| ms- s _ m. -- I
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| . _ _ . . - - . _ . - =-
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| 2071 04 14 54 ef$:DAVbur explosive runaway due to the big increase of reactivity.
| |
| 'l 1, l 2 'My real question is could that occur in 3 U.S.' graphite reactors?
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| 4 MR. EBERSOLE: You qualified it when you said 5 graphite.
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| 6' MR. ETHERINGTON: Did I say graphite? That is 7 right.
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| 8 MR. EBERSOLE: G raphite , okay.
| |
| 9 MR. ETHERINGTON: That is what people are 10 comparing.them with.
| |
| 11 MR.-SHARON: We will discuss the Fort St. Vrain 12 reactor in Section 6, I believe. So we will get to that in gg 13 terms of reactivity accidents.
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| ~
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| t 14 MR. EBERSOLE: The fire was a consequence of the 15 original explosion, wasn't it? As a matter of fact --
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| 16 MR. SHARON: We understand it was basically the
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| : - l'7 pieces of not graphite and fuel that landed on combustible 18 surfaces, like the roof, that started the fires.
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| '19 20 21 i
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| 2071 05 01 55 DAVbw 1 MR. EBERSOLE: The fires didn't initiate the 2 accident. It was a consequence of it.
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| 3 MR. SHARON: That's what we understand; yes.
| |
| 4 DR. OKRENT: Some might argue that we should let 5 the plume just go up and carry it off.
| |
| 6 DR. OKRENT: I think we'd better let Mr. Sharon 7 move along, so that we have some time at the end for general 8 discussion.
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| 9 (Slide.)
| |
| 10 MR. SHARON: Again, we would also state that 11 there should be consideration of a program for accident 12 management, particularly training and procedures for scoping 13 with severe core damage and for managing and insuring that 14 containment stays intact.
| |
| 15 This area is mostly going to be addressed under 16 severe accident policy implementation program, where we wil 17 go out and do the individual plant examinations and look for 18 the vulnerabilities. We think that one area that might fall 19 out of this is to look at the need for accident management 20 procedures for severe accidents, in order to help reduce 21 vulnerabilities in the plant, as a result of operators not 22 being able to properly cope with a severe accident.
| |
| 23 This program, as you know, is under way.
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| 24 If anybody has any questions, Dr. Rosztoczy is
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| ,'~' 25 here. If anybody has any questions, he could probably ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(O Nationwide Coserage NR34(M6
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| ~ --
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| A
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| ?2071-05i 02 56 1ry.[DAVbw - l' . elaborate a little more on exactly what areas we would be
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| : 1) 2 looking7at.
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| 3 The next area is, we would take~a look at the
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| : 4. ' administrative controls that govern: technical review and 15 approval of changes, tests and experiments.
| |
| 6 What we.are talking about here is the 5059
| |
| ~7 reviews. Whenever a plant does a change or wants to perform ~
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| 8 a test.to the reactor or'the plant, it must review it 9 against the criteria in 5059, which are, does it create an
| |
| .l.0 accident of a different nature? Does it create an accident 11 more severe than the one previously analyzed,'or does it 12 increase the frequency of an accident that was previously
| |
| - 13 analyzed, and if it passes on any one of those three, then
| |
| : 14. one has to do an evaluation, and it has to be submitted to 15 the NRC for review.
| |
| ! 16 This review, this assessment, is typically done j 17 first internally by the plant safety committee, PORC. One 18 of the things that we recognized previously, while
| |
| ; 19 certainly, these committees are diligent in their review of 20 this in making sure that the 5059 criteria are examined.
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| : i. 21 There seems to be a diversity in the depth to 22 which one does an evaluation against 5059. Obviously, 23 different changes to the plant would warrant different 24 depths of evaluation.
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| 25 One program that is ongoing is at NSAC, the
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| 1 2071 05 03 57 I DAVbw 1 Nuclear Safety Analysis Center, which is part of the EPRI 2 organization.
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| 3 It is developing a report, a guideline, which 4 would try to standardize the 5059 reviews, in terms of, 5 given what kind of changes you would like to make to the 6 plant, what type of evaluation, what depth of evaluation 7 should you perform. This would give you some degree of 8 consistency in these reviews. So we are working with them.
| |
| 9 We are encouraging them to complete this effort.
| |
| 10 DR. OKRENT: I wonder if that kind of general 11 guidance can take the place of actual detailed knowledge of f 12 the plant design, the plant safety issues and so forth and 13 so on hy the engineers and operators, whom are involvee in 14 such a review. As one just listens to operating experience, 15 as we did this week, you see fine points about each plant, 16 that were they not recognized ten years from now while 17 somebody was proposing to do something, could create a 18 severe vulnerability, things that would never be in general 19 guidance.
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| 20 MR. SHARON: I think you have raised a question 21 that the Staff has already latched on to in some aspects. I 22 don't know if you've heard any presentations on this PRISM 23 program.
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| 24 DR. OKRENT: I have.
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| 25 MR. SHARON: I think this is a first step, and ACE-FEDERAL REPORTERS, INC.
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| -., ~ _ . < - , , , _
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| r 2071 05 04 58 DAVbw 1 what it is is to try and computerize the PRAs.
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| 2 DR. OKRENT: If the Staff was running the PRISM 3 program, is that correct?
| |
| 4 MR. SHARON: Right now, it is Research that is 5 developing it, but I think the industry is very interested 6 in it as well. I think, typically, if we use it -- if we 7 take it on as a useful tool, the industry typically follows 8 and picks it up, because they do not want us, number one, 9 telling them when their plants are not safe. So we are 10 hoping that the industry would take the lead in this area as 11 one way of assuring that they don't put the plant into an 12 unsafe condition or a high risk condition by making 13 changes that haven't been properly evaluated from a PRA type 14 of standpoint.
| |
| 15 DR. OKRENT: You sort of lead me to ask a 16 question.
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| 17 Do you really think the PRISM program is the wave 18 of the future, and why bother with IPEM? Why not move
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| {
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| 19 strongly in that direction for each plant?
| |
| 20 MR. SHARON: I just don't think the PRISM program 21 approach is ready yet for global. Number one, it has to be 22 based on an existing PRA, but I think there is only about 30 23 plants that have PRAs today. We would have to get PRAs for 24 the rest of the plants before it could really be applied.
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| ~
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| 25 So it is something that is coming down in the future, and I ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage $X A3 hf616
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| e.
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| 2071 05 05 59 DAVbw 1 don't think it is appropriate at this time to delay doing a 2 vulnerability search, using the IPEM, the individual plant 3 examinations, because this will be something that is done in 4 a relatively short period, say, about a year and a half, two 5 years, and hopefully, it is going to bring to the surface 6 any glaring vulnerabilities which, I think, is appropriate 7 to fix rather than wait several years before this method 8 really becomes useful, and even then, we may not have PRAs 9 for all the plants.
| |
| 10 DR. OKRENT: Go ahead.
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| 11 MR. SHARON: The last item here is the review of 12 engineering safety feature status displays and their 13 availability and see if there is any areas that are 14 worthwhile for making improvements to it.
| |
| 15 I think this is straightforward. We just want to 16 make sure that these displays are to be available to the 17 operators. Some of them are not available all the time.
| |
| 18 They are not required to be, so this is an area where we 19 want to see if there is some improvement.
| |
| 20 MR. EBERSOLE: Brian, may I ask a question?
| |
| 21 Consider the effects of not having what I call 22 having the red book, which is a detailed listing of 23 prohibited actions and operations. There is a lot of 24 f reedom above a set of constraints that you presently have
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| '~ 25 and ingenious operators can take actions, which are not ACE-FEDERAL REPORTERS, INC.
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| 202 347-3700 Nanonwide ros erage
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| * R L 3 bfM6
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| r 2071 05 06 60 DAVbw 1 explicitly prohibited.
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| 2 I will give you a case in point.
| |
| 3h In bypassing blow down on a boiler, the man's got 4 90 seconds to do something, but he isn't told what to do in 5' that 90 seconds. There is a set of explicit prohibitions 6 that prevent him invading the proper action of the automatic 7 function. You can find these all over the place. The 8 operator, in the absence of being absolutely forbidden a 9 course of action, is pretty well on his own. Who is going 10 to tell him not to. So I understand the need for the red 11 book.
| |
| 12 I would have thought such a thing like that might
| |
| --s 13 have prevented Chernobyl. It is a piece of paper in front 14 of you, saying that you will never enter this regime.
| |
| 15 MR. SHARON: My understanding was that it didn't 16 exist, not maybe as a red book that says you will not do 17 this, but for example, we have tech specs which say systems 18 can't be taken out of service, and if they are taken out of 19 service, then they go in an action statement that says these 20 should be restored to service or you shut the plant down in 21 so many hours.
| |
| 22 MR. EBERSOLE: But it is very low key. It is not 23 the kind of thing you can remember.
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| 24 MR. Sil ARON: I agree that we should it under 25 consideration, and it is something we should look at as a ACE-FEDERAL REPORTERS, INC.
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| 2071.05 07 61 DAVbw 1 longer-term item.
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| 2 Unless there is any other question on the 3 operations, I would move over to II, which is the design 4 aspects.
| |
| 5 (Slide.)
| |
| 6 And our conclusions here, the first one, which is 7 the reactivity accidents, we took a hard look at these. We 8 concluded that a) we don't have positive void coefficients 9 that the Chernobyl reactor had. It is not there. We do 10 have some positive moderator coefficients early in cycle, 11 usually, but once you start burning up the fuel, these 12 again, go negative. We did a systematic review of the 13 design basis accidents, the transients that we look at in 14 our FSARs. We did not see any of those that indicated there 15 was something that we were doing wrong.
| |
| 16 What we did look at is, if I carry these design 17 basis events one step further, I guess, to extend them, for 18 example, instead of having one rod withdrawal, I can 19 withdraw many rods, or instead of one bank of control rods 20 withdrawing, I would withdraw many banks at the same time.
| |
| 21 There are ways that one could theoretically put 22 reactivity into the reactor, in essence, of what we analyze 23 -- what I should say is, a long time ago, a judgment was 24 made, when the design basis for these plants was being
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| (^ 25 developed, that these events were either precluded by ACE-FEDERAL REPORTERS, INC.
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| mm.- ~ _ m- - > , -
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| 2071 05 08 62 DAVbw 1 physical features in the design or were of low enough, 2 extremely low probability, that one need not consider them 3 in the design base. It is kind of hard to go back and 4 dredge out all the rationale for why these events were not 5 put in.
| |
| 6 Our look at them right now indicates that we 7 still think they are in a very low probability, or they are, 8 l indeed, precluded by design features.
| |
| 9 Nevertheless, we are a lot smarter now than we 10 were 15 years ago when these things were probably first 11 developed and came about. And we think it might be 12 appropriate to go back and take a look at these, using the 13 more sophisticated tools we have available.
| |
| /
| |
| 14 We, at PRA, are just looking at it from a more 15 deterministic standpoint with our knowledge of the design, 16 and just reconfirm that what we did in the past is, indeed, 17 correct.
| |
| 18 MR. EBERSOLE: This doesn't include a review of 19 the BWR ATWS, does it, which is a reactivity ATWS? This is 20 not in the ATWS scope?
| |
| 21 MR. SHARON: No. We were not really considering 22 to do a complete reexamination of the ATWS, okay.
| |
| 23 MR. EBERSOLE: I am talking only about the BWR 24 ATWS, the configuration where they get the excursion when 25 they have a transient. Okay.
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| ACE-FEDERAL REPORTERS, INC.
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| 20244747(M) N.uion aide roserage f4WK346M6
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| 7 2071 05 09 63 DAVbw 1 DR. MARK: From something I read, I was very 2 impressed with the marvelous idea that their control rods 3 first put in graphite to displace water, as they moved. I 4 don't think we have anywhere anything with that 5 characteristic, but that, by itself, was a beauty.
| |
| 6 MR. SHARON: Keep in mind that I think when these 7 rods had the graphite follower on them, remember that these 8 rods were pulled out well beyond their normal limits. These l 9 rods were only supposed to be pulled out, so they were still 10 like 1.2 meters in the core itself. So the graphite, I 11 think, would have been sitting somewhere in the core 12 region. So when you did scram, it would not be a positive 13 insertion, whereas, in order to compensate for that xenon 14 that was building up in that core, they pulled these rods 15 well beyond the administrative limits. They were almost 16 completely out of the core. So now when they did scram, 17 that graphite had a movement to the core region before it 18 moved out, and that is what caused that positive scram, as 19 they called it, where you got the positive insertion before you got the negative.
| |
| 20 l 21 DR. MARK: I don't argue with you at all, but it 22 was an absolutely beautiful feature that they managed to 23 achieve.
| |
| 24 DR. REMICK: In some nonpower reactors, there are
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| ~
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| 25 rod followers. Anything from aluminum to fuel, following l
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| ACE-FEDERAL REPORTERS, INC.
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| mm , ~ _ m <- --
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| (2071'05 10' 64-
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| -<f( DAVbw . 1 .the rods.
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| ! l 2 I don't think, in our power reactors, we have 3, that.
| |
| 4 DR. SHEWMON: These things you all call rod 5 followers are rod preceders, literally. They come into the
| |
| : 6. core first.
| |
| 7 DR. REMICK: As the absorber goes out, you are 8 adding something in, and that is-how you look at it.
| |
| a 9~ DR.'OKRENT: By the way, just a small point, but 10 when you say " positive void coefficient," that is not quite 11 rigorously true, and your words were different. You may 12 just want to think about you would present that.
| |
| i
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| ,, -) . 13 MR. SHARON: Okay.
| |
| (_/ 14 The next item, II, number 2, these are accidents 15 at low power and shutdown. I am not going to dwell on 16 this. What it is, is that we found several years during a 17 review, I think it was of Wolf Creek, that one could 18 possibly design basis events occurring at shutdown, where, l
| |
| 19 in conjunctions with the tech specs that were being 20 proposed, it resulted in consequences that were in excess of 21 the original design base.
| |
| 22 The one I would point as an example is the rod 23 withdrawal accident. If you analyze the rod withdrawal, in n
| |
| 24 which the worst case now is at startup, and they calculated 25 the withdrawal of one rod bank and the tech specs said,
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| }
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| ACE-FEDERAL REPORTERS, INC.
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| 202 347 3700 Nationside Coverage mn336-(M6
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| - - , . < . . - . - , , _ . . . - _ .. - . _ , - . . _ _ _ , , . _ _ _ - . . . . . - _ _ . _ = _ _ . - - . , - , _ . . . _ . , - . . . - - , _ _
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| :2071-05 11 65
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| 'j-]-DAVbw' -l when you.are'in startup, you'either have -- some
| |
| \)
| |
| 2 -Westinghouse plants have to have two pumps running. .Others I
| |
| 3 have to have four pumps running.
| |
| 4 The events were analyzed in the FSAR, assuming 5- either two pumps or four pumps.were running.
| |
| 6 When you go to mode 4, which is hot. shutdown, 7 tech specs only required one pump to be running.
| |
| 8 If you analyzed rod bank withdrawal with one pump 9 ' running, the event got worse. It didn't turn into a core 10- melt. -You were just going from a condition where you didn't 11 exceed D&B limit. You exceed the D&B limit.
| |
| 12 What it did is, it pointed out to us, when you
| |
| - gg 13 look at the tech specs, there may be tech specs in the O
| |
| 14 shutdown modes'that allow systems to be taken out of 15 operation that may, indeed, be required or wore required
| |
| : 16. within the design basis to be functional. Yet the 17 assumption always is that if I postulated the event at 18 shutdown, it would be bounded by the event, when it is 19 postulated to occur in power or at start up.
| |
| F. 20 So we think it is appropriate, and we've done 4 21 this review on McGuire. We went off, and we had a l 22 contractor, Iberando Scientech, take a look at the McGuire 23 tech specs. I think they found something lite half a dozen 24 discrepancies, where the tech specs either precluded one
| |
| {} 25 being able to draw a conclusion that a certain event was l
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| . ACE-FEDERAL REPORTERS, INC. l 202 Nationwite Coserage 8(XA33MM6
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| - . __ _ -- -- ._ _147 3 7(X). - _ , - - . ~ . _ . . - - _ . - _ _ . . . . _ , . - , , . _ . _ . . _ . . ~ - - . _ - . . _ . . . . . . . . -
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| | |
| 2071 05 12 66
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| ,~' DAVbw 1 bounded by the design base. So we think it might be i
| |
| 2 appropriate for somebody, and I won't say who yet, whether 3 it is the Staff or whether we ask the industry to go back 4 and reconfirm that the tech specs are, indeed, consistent 5 with the design base, as they presented it.
| |
| 6 Another example was, I think, TMI, the proposed 7 tech specs, to insure that there were at least two paths 8 available for decay heat removal during shutdown.
| |
| 9 One of their proposals was, we have a tech spec 10 that says either you have on coolant loop running and one 11 decay heat removal train available, or you have two decay 12 heat removal trains available, or you have two loops c'. .
| |
| 13 available, two reactor coolant 1; ops running.
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| 6 j
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| 14 15 16 17 18 19 20
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| , 21 22 23 24
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| 1 1
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| 2071 06 01 67 DAV/bc 1 What happened is, under that tech spec that said 2 you could have one reactor coolant loop running, you now had 3 a situation where you had one pump that was running.
| |
| 4 We said, if you postulate your design basis 5 accidents in the shutdown mode with only one loop running, 6 can you tell me that you bound all of your design basis 7 events?
| |
| 8 The answer was: We don't know.
| |
| 9 So it's stuff like that we want to make sure is 10 not being missed in the design of these plants.
| |
| 11 MR. WARD: Brian, I guess I'm a little troubled 12 there. I don't know how you're going to insist on or 13 develop or encourage some systematic way of looking at those 14 sorts of things. Even depending on tech specs, you know, 15 you really need some layers of protection there.
| |
| 16 Tech specs can be violated. Obviously, that's 17 what happened at Chernobyl. Their equivalent of tech specs, 18 several of them, were violated.
| |
| 19 How do we have such high confidence that they'll 20 never be violated in U.S. plants?
| |
| 21 MR. SHARON: I think, if you go back to our 22 conclusions and our assessment in Section 1, which is the 23 Operations section, no, one cannot absolutely guarantee that 24 an operator will never violate a tech spec.
| |
| '") 25 We hope, and I think we discussed this at the ACE-FEDERAL REPORTERS, INC.
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| - ,, x _ m- ..~
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| -207l'0'6 02 68
| |
| 's .DAV/bc 1 subcommittee meetings, you can't regulate safety or you x_/ .
| |
| 2, can't regulate the attitudes of people. We just can't write 3 a regulation that says you will have a good attitude toward 4 safety.
| |
| 5 That's something that we just can't do. What.you 6 can do is you can try to provide the atmosphere and the 7 incentives to make sure that these people are indeed 8 sensitized to recognize that they can't just willy-nilly 9 ' violate their tech specs if it's convenient to do so.
| |
| 10 That's what we hope that we've done through the 11 operating procedures, the training programs, and the like, 12 for these operators, is to have a healthy respect and 13 understanding of the safety of the plant and that the v
| |
| 14 procedures, the rules and everything are there for their 15 protection.
| |
| 16 They're there for a reason. Not because the 17 regulators want to be stinkers and provide a bunch of 18 obstacles for the operators.
| |
| 19 So the answer is, you know, you can't give a 20 hundred percent guarantee but we're going to strive to give 21 as much as we can.
| |
| 22 DR. OKRENT: Brian, getting back to Jessie 23 Ebersole's question on ATNS as a reactivity accident, I 24 recognize there's a different kind of reactivity feedback,
| |
| (} 25 but I wonder if anyone has spent a little bit of time trying ACE-FEDERAL REPORTERS, INC.
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| 202-347 3700 Nationwide Coserage 14XK3%6M6
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| -2071 06.03 - 69 ic"y. DAV/bc 1 to see if there are a set of circur. stances that might make i''j'
| |
| '2 -that first portion of th'e ATWS event significantly worse.
| |
| 3 I'll mention'something that may, in fact, be a 4 very bad, a' wrong direction.
| |
| But, right now, I envisage the 5 water comes in at a certain temperature. If the water came 6 in colder, you might have to get to, in effect, more voids
| |
| '7 in order to be at the same average density, the same 8 reactivity, more voids to collapse; maybe, therefore, 9 greater reactivity to be gained in the first phase when you 10 get an MSIV closure.
| |
| 11 That might turn out to be a nonevent or a trivial 12 event. But one might at least try to see if there are ways q 13 that could change the character of the ATWS from what it is LJ as it's currently analyzed to see if it moves one into a
| |
| ~ 14 15 temperature range for the fuel that you don't like, for 16 example. Okay?
| |
| -17 MR. EBERSOLE: As I look at it, the positive void 18 coefficient applies to the case where you're operating with 19 little or no voids and you get some more of them, you'll 20 shut down.
| |
| ; 21 But it's the reverse of the case where you always 22 operated with voids and you might get rid of them fast. So 23 it's just the inversion of the same problem that requires a ;
| |
| ~
| |
| +
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| 24 reverse view.
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| ~
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| {} 25 And if I look at all those things in which I l.
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| i ACE-FEDERAL REPORTERS, INC.
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| 20M47-3'tM) Nationwide Cmerage EXL346M6
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| c r2071.06 04- 70 1- ~might lose the voids faster, then I have heretofore l7-} DAV/bc' li 2 recognized a system reverse would be'the same_ problem.
| |
| 3 DR. REMICK: But, J essie, that certainly is
| |
| :4 . analyzed in transients.- Every time your MSIV slams closed 5_ and you collapse-the void, you get a positive reactivity
| |
| ~61 ' insertion.
| |
| 7 DR. REMICK: Suppose you were running with colder
| |
| .8 water coming in at the bottom of the core and, therefore, 9 had more voids to collapse?
| |
| 10 MR. EBERSOLE: And a turbine trip also with loss 11 of feedwater.
| |
| 12 MR. SHARON: T wish Wayne Hodgan were here. I 13 don't know whether, you know, but my understanding is we
| |
| 'O 14 -have told the BWRs that'they're not allowed to operate with 15- an inlet temperature below some number to compensate for the 16 loss of feedwater heating.
| |
| 17 DR. OKRENT: You see, now we're getting to it 18 again. The Russians were told they weren't supposed to do 19 something. Right? Okay. It's one thing to count on a tech 20 spec. It's another thing to see, even if they violate the 21 tech spec, they can't really give you so severe an excursion 22 you're worried. Okay?
| |
| 23 MR. SII ARON : Okay. The next item is the multiple 24 unit protection. I guess the first thing is that, right 25 now, we've taken a look at the control room design. A
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| }
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| ACE-FEDERAL REPORTERS, INC.
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| 2071 06 05 71 DAV/bc 1 number of action items came out of the TMI accident 2 regarding control room habitability under severe accidents.
| |
| 3 The issue was deferred into the general category I think it 4 was Roman IIB 8 of the action plan, which was severe accident 5 rulemaking.
| |
| 6 As you know, the severe accident rulemaking was 7 superseded by the severe accident. policy statement which we 8 are implementing right now.
| |
| 9 The efforts related to looking at control room 10 habitability and design in regard to this realistic source 11 terms if currently being addressed in a revision to the 12 standard review plan, which I was told this morning is on my g 13 desk and I should sign today to get to the CRGR. That's a
| |
| '~
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| 14 revision to Section VI.2.5.
| |
| 15 VOICE: VI.5.5.
| |
| 16 MR. Sil ARON : I'm sorry.
| |
| 17 So that area is well in progress.
| |
| 18 DR. REMICK: Can I understand something?
| |
| 19 Whatever it is that's in this new version of the standard 20 review plan, with multi-unit plants as they're currently 21 designed, if one got a release ala Chernobyl, would the 22 other plants on the site be able to be habitable?
| |
| 23 MR. Sil ARON : I think our conclusion was the 24 control rooms would have high confidence to be habitable.
| |
| (~) 25 They were not specifically designed, I don't believe, for V
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| l ACE-FEDERAL REPORTERS, INC.
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| :c: nn, ~ _ . ~ ... --
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| r 2071 06 06 72 DAV/bc 1 like a category one release.
| |
| 2 DR. REMICK: I'm aware of that, but I'm asking 3 the question and I don't know what you're asking in your new 4 version of the SRP.
| |
| 5 MR. SHARON: Glenn, do you want to say a few 6 words about what's in there?
| |
| 7 MR. SOFER: Glenn Sofer, NRC.
| |
| 8 The SRP revision that we're talking about right 9 now addresses simply the use of BWR suppression pools as 10 part of the cleanup systems. We have not yet reached the 11 question of looking at control room habitability under 12 severe accidents.
| |
| 13 That's to come next spring. So we haven't yet 14 factored that in.
| |
| 15 MR. SHARON: I apologize. I was getting confused 16 between sections. That one is supposed to be the revision 17 of 6.2.5?
| |
| 18 MR. SOFER: I believe it's SRP 6.4, Brian.
| |
| 19 MR. SHARON: Close enough. Okay. So we will be f 20 looking at that revision to the control room habitability 21 using realistic source terms. And as Len said, that will be 22 out in the spring.
| |
| 23 ,
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| We have also recommended it for future plants, i
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| 24 ' We will be looking at this as part of the advanced BWR as
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| ) 25 ; well as the EPRI white water reactor requirements document.
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| I ACE-FEDERAL REPORTERS, INC.
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| ,2 m .., ~ _ _ - ._
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| 7 2071~06 07 73 1 We dan't think they should be sharing systems
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| ("] DAV/bc J V l 2 that are part of a shutdown capability to prevent accidents I
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| 3 of one unit affecting accidents at a second unit.
| |
| i 4 MR. BBERSOLE: Let me ask you a question about i
| |
| 5 that. That implies condemnation of sharing at large. Most j 6 sharing is designed to save putting an extra system in a f 7 unit.
| |
| ( 8 If you do that, you know, once you've put an 9 adequate number of systems in the unit, I don't see anything i
| |
| 10 wrong with them sharing the flexibility that happens to the 11 others accessible to it.
| |
| 12 MR. Sil ARON : Let me qualify this a little bit. I 13 understand what your concern is. What we're seeing here is
| |
| (-)
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| v 14 that if you're going to share equipment, make sure that an l 15 accident, for example, at one unit is not going to take out 16 the second unit.
| |
| 17 In severe accidents, obviously, there are some 18 benefits to sharing.
| |
| j 19 MR. EBERSOLE: Just don' t share to be cheap and 20 not have enough facilities at the first unit anyway.
| |
| 21 MR. Sil ARON : Yes.
| |
| l l 22 MR. EBERSOLE: Most sharing is done for being 23 chinzy. That's the wrong way.
| |
| I 24 MR. Sil ARON: You're saying if sharing is there, l
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| 25 obviously, which enhances safety, we don't want to preclude
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| [
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| I l
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| l ACE-FEDERAL REPORTERS, INC.
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| m.wn, u.a- + a-,. --
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| ~207l'06 08 74
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| . N DAV/bc 1- th'at.
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| F ).
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| 2 .IMt. KERR: If that's the case, it seems to me l 3 that sharing is not the thing that you should be
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| ~
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| 4 discussing. It's inadequate equipment, period.
| |
| 5 11R. SHARON: This may be a poor choice of words, 6 and we can certainly try and clarify that.
| |
| 7 .DR. OKRENT: Uncontrolled interconnection.
| |
| 8 DR. MOELLER: Well, now, if the control. room 9 habitability system in a second unit was adequate to protect 10 the operators from an accident in the first unit, can we 11 also' assume then that if the control room in the first unit 12 has'an equivalent habitability system, that it's protecting
| |
| -s 13 its operators?
| |
| i 14 Can we just assume that your review will assure 15 that the operators in the control room of the unit having 16 the accident are also protected?
| |
| 17 MR. SHARON: Yes.
| |
| 18 DR. OKRENT: If the accident didn't somehow 19 damage the integrity of the control room itself.
| |
| 20 DR. MOELLER: Correct.
| |
| 21 MR. SHARON: The last time -- I just wanted to 22 point out, which we had identified last time, was that if 23 operators had to leave a control room to shut the plant 4
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| 24 down, which they have to do -- one has to go out of the 25 control room and wrack in the motor operators for the f
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| I i ACE-FEDERAL REPORTERS, INC.
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| x.m.m _ m c _ ,, -
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| 2071"0'6iO9, 75 M ; DAV/bc 'I accumulator isolation valves which are locked open during.
| |
| i-' 7g; ''(,o ,
| |
| 2 operation -- Appendix R requires for most plants, I believe, 3 that the RHR isolation valves be locked closed because of 4 fire concerns; mainly, .because they don't have the 5 separation and that a fire could potentially cause both 6 valves to open.
| |
| : 7. So these are locked close by removing power.at 8 the motor control center. Again, an operator would have to 9- go out'and restore power to'the motor control canter.in 10 order to open those valves.
| |
| 11 So an operator does have to leave the control 12 room in order to bring a plant to cold shutdown.
| |
| .- 13 The concern was that, well, if I had an accident y
| |
| :/s.
| |
| in an adjacent unit, would I make the environment
| |
| . 14 15 inhabitable so that the operator could not go out and take 16 these actions?
| |
| 17 We took a hard look at this and there's a number 18- of arguments that would indicate why this is not really a 19 problem. This is why we eliminated it.
| |
| 20 One is, even if there was some sort of a 21 radioactive environment, these actions are not actions where 22 an operator has to go out and stay there. The operator goes 1
| |
| 23 out, takes the action and goes back.
| |
| 24 So these operators can suit up with breathing 25 apparatus and the like, and go out and take these actions, i
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| : ACE-FEDERAL REPORTERS, INC.
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| m.m.m., s.- m r_... m.os -
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| t
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| 2071 06 10 76 t ,. .
| |
| p ?As;'DNh/bc "
| |
| 1 presuming that there was a harsh environment. !
| |
| x ,/- ?
| |
| 9- 2 Number two, we don't really think there's going li 3 to be a very harsh environment over in these areas in the av 4 other plant.
| |
| 5 And, three, if you had an accident at one unit, 6 'unless you're talking about something 2 hat proceeded very N 7 quickly-and failed containment very quickly and had a big 8 . release, but if you look at the more probable type of
| |
| : 9. scenario where one has slow over-pressurization and a late 10 failure, these operators are going to know that there's a 11 problem. .And they're going to go and shut down that other
| |
| : 12. unit. ,
| |
| 3 13 And they're going to be able to go out snd take O '
| |
| 14 these actions before there really is any harsh environment.
| |
| 15 So all those factors coupled made us believe that we really i '16 didn't think that there was some definitive action that 17 could be taken in the design that would make those areas 18 more habitable.
| |
| r 19 For this reason, we have eliminated it from our
| |
| ~
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| 20 list of areas that we want to study further at this time.
| |
| \' i' ,
| |
| 21 MR. EBERSOLE: In that connection, it may well be l[ 22 that in severe accidents, the containment is breached into i
| |
| kh 23 the equipment room because of the design of the penetration s 24 system.
| |
| 25 That produces a concentrated ATWS. You know, a
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| \ .
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| ; ACE-FEDERAL REPORTERS, INC.
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| Nationwide Coscrage fm33M686 202-347 3XU A. . _. _ . - . _ . . ~ _ _ . , . , ,. _ _ _ . _ _ . _ _ , - . . . , _ ___,,, . -.___. ,, ,~. ._._ _ , . , , , - . _ _ . _ _ _ _ ,
| |
| | |
| 2071 06 11 77 DAV/bc 1 plume, which is a little hasty to go into.
| |
| 2 Are you with me?
| |
| 3 MR. SHARON: I understand. I think, from that 4 standpoint, that may be something that would come out of the 5 severer accident vulnerability studies.
| |
| 6 We would hope, you know, that, in the plant walh-7 downs and the like, that this stuff would be observed. If 8 there was a failure of the containment, a weak point.
| |
| 9 MR. EBERSOLE: I think most of them are that 10 way.
| |
| 11 MR. SHARON: That it would fail into a place.
| |
| 12 MR. EBERSOLE: In other words, it's not an 13 atmospheric event between the equipment room and the 14 containment.
| |
| 15 MR. SHARON: That may be an area we can single 16 out if we see that.
| |
| 17 DR. KERR: If I understood what you were talking 18 about earlier, you were not talking about operators doing 19 something that would damage the plant. You were talking 20 about what operators would do in the adjacent plant, weren't 21 you?
| |
| 22 MR. SHARON: If you've already melted the core, 23 you're not really worried about trying to get RHR going, I 24 don't think, or trying to worry about an accumulator
| |
| ( 25 isolation valve that's open.
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationaide Coserage M433M646
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| I 2071 06 12 78 DAV/bc 1 Okay, it's in the undamaged units. So the real 2 question is:
| |
| l 3 Can the containment in a damaged unit fail such 4 that<it could perhaps produce a harsh environment into the 5 areas that one needs to go in the undamaged area.
| |
| 6 MR. MICIICLSON: Or that equipment needs to 7 operate in the undamaged unit to prevent damage to the other 0 unit.
| |
| 9 I doubt that you've chased this sort of thing. I 10 asked a few of these questions relative to generic issue 61, 11 which has a potential containment failure, whether or not 12 the environmental effects of the containment failure have 13 been included in the examination.
| |
| ~
| |
| 14 And the answer was: No. For generic issue 61, I 15 was surprised. They had a strange-looking probability of 16 melt-down, even if you get containment failure, like only I
| |
| 17 one chance in 10.
| |
| 18 I asked: Does that include environmental 19 effects?
| |
| 20 The answer was: No.
| |
| 21 MR. SHARON: The last area under design is
| |
| (
| |
| 22 Fires. The concern here was again at Chernobyl. The j l
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| 23 firefighters were being asked to fight fires in the presence 24 of radiation. A number of things they did. One was they 25 took off their protective clothing, which further exposed ACE-FEDERAL REPORTERS, INC.
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| 202-347 3700 %tionwide Cos erage 80th346M6
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| 2071 06 13 79 DAV/bc 1 them to radiation. One of the things we want to make sure 2 is that we have adequate provisions at nuclear plants to 3 cope with fires.
| |
| 4 We've taken a look at the firefighting measures 5 as provided by Appendix R, and adjusting other firefighting 6 measures that are put into the plant design.
| |
| 7 We think that the operators have the proper 8 protective equipment, the self-contained breathing 9 equipment, turncoats, and so forth, to fight thesa fires.
| |
| 10 It's available. They have trained fire brigades.
| |
| 11 These fire brigades have a health physics type on 12 them which advises them regarding radiation if they're 13 fighting any sort of a fire that has radiation associated 14 with it.
| |
| 15 The design is such that there are fire-retardent 16 materials on the roofs of nuclear plants in the U.S. They 17 use standpipes for booking up and getting water up to higher 18 elevations.
| |
| 19 One of the concerns at Chernobyl was that they 20 had no way of getting firefighting equipment to the roofs of 21 the building other than by ladders.
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| 22 23 24 25 ACE-FEDERAL REPORTERS, INC.
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| 2:12-347-37(O Nationside Co$ erage $ n 346M6
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| 2071 07 01 80 DAVbur 1 I don't know whether the Chernobyl plant or 2 others have standard stand pipes for being able to hook up 3 fire hoses on the roofs, there are access locations to get 4 to the roofs of the buildings, and the like.
| |
| 5 And I think the biggest thing we have to 6 remember -- and Jesse pointed this out before -- and that is 7 this was a unique situation where I had 30 fires flaring up 8 all at once in various parts around the plant because of hot 9 fuel that was spewed out. So I had a much, much higher 10 radioactive source term in conjunction with the fire than I 11 could probably ever postulate in a U.S. plant because we 12 just don't see how one is going to get this kind of an x 13 accident that is going to, A, spew the core around and, B,
| |
| ~~
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| 14 spew it around in such a manner that it is going to start a 15 lot of fires.
| |
| 16 DR. MARK: You did refer -- and it has been 17 referred to before -- to protective clothing. Now, there is 18 no protective clothing that does a damn thing about gamma 19 rays.
| |
| 20 MR. SHARON: That is correct. Gammas are not 21 going to be stopped by any kind of protective clothing.
| |
| 22 Just the betas.
| |
| 23 DR. MARK: It was beta burns that did them in?
| |
| 24 MR. SHARON: I apologize, Frank Cargill is not J~1 25 here.
| |
| LJ ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage 80Lk3346M6
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| 2071 07 02 81 DAVbur 1 I asked him about this. He told me really it was 2 the gamma dose for some of them that really caused their 3 deaths.
| |
| 4 MR. WARD: What is a beta source that isn't also 5 a hard gamma source?
| |
| 6 I have trouble understanding that.
| |
| 7 DR. KERR: At least memory would indicate that 8 some of the burns that these people had were not just 9 thermal burns.
| |
| 10 MR. Sil ARON : That is right. There were a lot of 11 beta burns. That is what I understand. It is because they 12 took their clothing off it was so hot, and without having 13 the protective clothing on to stop the betas....
| |
| 14 DR. KERR: There still is not much to do with a 15 gamma dose.
| |
| 16 DR. MARK: I was just curious about this because there must have been a ferocious gamma dose available for 17l 18 which protective clothing would mean nothing.
| |
| 19 MR. SHARON: That is correct.
| |
| 20 DR. KERR: One of the problems they had, I think, 21 was treating the skin burns, particularly for people who had 22 almost completely....
| |
| 23 DR. MARK: Once in the hospital, this would be 24 tremendous.
| |
| 25 MR. WARD: Did you understand why there was such
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| ~
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(O NallOftwide C04CragC MO33bM
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| ~
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| 2071 07 03 82 DAVbur 1 a high, apparently, beta field?
| |
| 2 DR. KERR: Sure.
| |
| 3 DR. REMICK: The smoke must have contained a lot 4 of particulate matter.
| |
| 5 DR. MOELLER: I presume this was skin 6 contamination that had the heavy beta dose.
| |
| 7 MR. SHARON: That concludes the section on the 8 design implications.
| |
| 9 The next area is III on the list. This is the 10 area of the beyond design basis containment and venting.
| |
| 11 (Slide.)
| |
| 12 MR. SHARON: Obviously, Chernobyl didn't have a 13 containment as we know it over here. I don't want to say
| |
| ~'
| |
| 14 what they had. I am not sure. I would call it more of a 15 confinement type of arrangement.
| |
| 16 It had no pressure retaining capability. It did 17 not have any sort of a spray system or venting system as far 18 as I understand, and because of that it is very difficult to 19 draw any sort of an analogy between containments around 20 U.S. reactors and Chernobyl.
| |
| 21 However, it did point, I think very rightly so, 22 to the benefits of a containment. We have taken a look. We 23 think that if there was a large, dry containment around 24 Chernobyl, it would have withstood the explosive force and
| |
| ''. 25 not released anything.
| |
| ~-
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3XO Nationaide Cos erage 80tL33M646
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| 2071 07 04 83 DAVbur 1 I think what it has done is it has just 2 reemphasized the need to look at containment performance in j 3 our evaluation of severe accidents.
| |
| 4 We are doing that right now. As you know, just 5 this afternoon isn't there a discussion on the containment 6 performance of the Mark I's by Mr. Bernero?
| |
| 7 There is an effort underway within Research and 8 NRR on the containment performance objective with regard to 9 the safety goals and also with our severe accident policy 10 implementation program.
| |
| 11 We would be looking at filtered venting for some 12 plants as a mitigation strategy to perhaps reduce 13 vulnerabilities.
| |
| 14 So with regard to the implications from Chernobyl 15 on containment, I think I would conclude by saying it 16 reinforced our need to take a hard look at containment 17 performance during severe accidents, and we will be doing 18 that.
| |
| 19 The next area is under emergency planning.
| |
| 20 We have taken a look at what the Soviets did and 21 what they had in the way of emergency plans following 22 Chernobyl.
| |
| 23 They distributed KI to the population. We were 24 told at Vienna that they had an evacuation plan, which was
| |
| ~
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| 25 quickly assessed and found not to be adequate, and they had
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| , ACE-FEDERAL REPORTERS, INC.
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| I nu- ~ . c- --
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| i 2071 07 05 84 DAVbur 1 to devise a new one on the spot.
| |
| 2 I think we later learned, or at least have 3 inferred that that plan that they had was really a civil 4 defense type of plan and was not specific to an evacuation 5 plan for that reactor.
| |
| 6 We have taken a hard look at the implications 7 with respect to the source term that Chernobyl had and the 8 type of failure.
| |
| 9 Again, remember, it was a mechanical dispersal of 10 the core. It literally blew the top off the reactor 11 building and spewed everything straight up in the air.
| |
| 12 The heat of the graphite, the air flow and the 13 like caused -- I think, J esse, you were pointina this out --
| |
| 14 produced such a massive heat source and a thernal source for 15 a plume to loft all of these particulates into the upper 16 atmosphere.
| |
| 17 This is one of the reasons that this stuff was 18 able to get over to the Scandinavian countries as fast as it 19 did.
| |
| 20 The Soviets told us in Vienna that they burned 21 something on the order of 25 percent of the graphite in the 22 core.
| |
| 23 So when you really look at it, Chernobyl had a 24 really unique source term.
| |
| 25 MR. EBERSOLE: Would it have been worse if they ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage Muk336-6M6
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| 2071 07 06 85 DAVbur 1 didn't have the fire?
| |
| 2 MR. SHARON: In terms of like a meltdown?
| |
| 3 MR. BBERSOLE: If they had their explosion but it 4 never caught on fire?
| |
| 5 MR. SHARON: That I don't know, quite honestly.
| |
| 6 I imagine it would have dispersed it a lot differently had 7 they not had the heat source. But we really don't know.
| |
| 8 They were asked at Vienna how much of the 9 graphite did indeed burn. They estimated 25 percent, but 10 how good that estimate is I don't know.
| |
| 11 As you know, prior to Vienna there was a lot of 12 controversy about graphite burning. There were experiments 13 done out, I believe, around Hanford, where DOE had some
| |
| ~
| |
| 14 contractors put an acetylene torch onto a block of 15 graphite. They sat there, they held it, and there was 16 swelling, I guess, and a depression in the graphite block.
| |
| 17 But it cooled so quickly once they took the flame away that 18 it didn't burn.
| |
| i 19 MR. EBERSOLE: There has been a great to-do as to 20 whether we got the graphite or not. I am not at all sure 21 that if it didn't burn it might not have just settled around 22 the plant and we might not have had a worse accident.
| |
| 23 MR. SHARON: I think the fires were dispersed, 24 and they said they were out by 5:00 o' clock in the morning.
| |
| ~
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| 25 Yet there were still releases going on until a week later, ACE-FEDERAL REPORTERS, INC.
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| 202 347-37tu) Nationwide Cos erage 8(X L 3346M6
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| 2071 07 07 86 DAVbur 1 which led me to believe or would lead me to believe that the 2 heat source was coming from the core region itself, and it 3 really didn't stop until they started dumping all that stuff 4 on it -- lead, dolomite, and sand.
| |
| 5 MR. WARD: The graphite fire wasn't out by 5:00 6 in the morning?
| |
| 7 Mr.. SHARON: No.
| |
| 8 MR. WARD: Those were the incidental fires?
| |
| 9 MR. SHARON: Like the tar paper on the roofs and 10 stuff.
| |
| 11 So, anyway, with the uniqueness of the source 12 term and the fact that they did not -- if they had an
| |
| , 13 evacuation plan specific to Chernobyl, they certainly didn't l
| |
| 14 tell us about it, and right now we don't know if one existed 15 or not.
| |
| 16 In any event, in looking at it, we concluded that 17 we think that the 10-mile plume EPZ continues to be 18 adequate. Then there is the 50-mile EPZ for the ejection 19 pathway, which we also think is adequate.
| |
| 20 Our emergency plans do not preclude taking 21 actions outside of that 10-mile zone if they are deemed 22 necessary. It is more of a guide than some sort of an 23 absolute rule.
| |
| 24 As you know, there is a number of efforts going r"., 25 on regarding EPZs and their adequacy or whether there is a s.- !
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage R4336446
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| 2071 07 08 87 DAVbur 1 basis to change them based on new' source term information.
| |
| 2 There is a lot of work going on in Research.
| |
| 3 There's some new regulations being drafted, I understand, in 4 this area.
| |
| 5 NUREG-1150 will factor into this, and I think our 6 conclusion is that we need to take the Chernobyl accident 7 into account and study it to infer what information we can 8 when we are indeed looking at the EPZs and any potential 9 changes to them.
| |
| 10 DR. MARK: Do you have a decent estimate of the 11 maximum dose at a 10-mile distance?
| |
| 12 MR. SHARON: I think we do, but I don't know it.
| |
| 13 I would have to go back. I think in our presentation that 14 we made, I believe September 12th, to the full committee 15 there was a table which listed doses for various communities 16 at certain distances from Chernobyl.
| |
| 17 Maybe if the ACRS staff could find that 18 presentation, that table would probably give you what you 19 want.
| |
| 20 DR. KERR: It certainly wasn't over 100 rems, was 21 it?
| |
| 22 MR. SHARON: No.
| |
| 23 DR. M ARK: Which bears very directly on your 24 comments just now of how our EPZs look because if that dose
| |
| ', 25 was, as I believe, more like 10 rem --
| |
| ACE-FEDERAL REPORTERS, INC.
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| 2071 07 09 88 DAVbur 1 DR. OKRENT: It was bigger. There were numbers 2 more than 50 reported.
| |
| 3 DR. KERR: Not at 10 miles.
| |
| 4 MR. WARD: As I recall, they told us the average 5 person in the Town of Pripyat got 3, but there were reported 6 doses up to 50.
| |
| 7 DR. OKRENT: In any event, the unusual nature of 8 the first part of the release, going up very high and going 9 past nearby people when you have a lot of the short-lived 10 activity, I think had that been released at ground level 11 things would have been quite different.
| |
| 12 DR. MARK: That is right.
| |
| 13 DR. MOELLER: A couple of comments.
| |
| ~
| |
| 14 One thing, of course, the accident clearly showed 15 was movement of the contamination or the radioactive 16 material extended over wide areas. This brings me to the 17 point that for that reason it emphasizes that it is 18 important for different countries to have compatible action 19 guide levels, and it would seem to me that one of the 20 lessons to be learned here is to look at Canada and the 21 U.S., which do not have comparable protective action 22 guides.
| |
| 23 So if we had an accident anywhere along the 24 Canadian border that caused material to move from the
| |
| '''; 25 U.S. to there, they might be taking action under one level
| |
| ~,
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-370l) Nationwide Cos crage R4336-(M6 i
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| I 2071 07 10 89 DAVbur 1 and we might be taking it under another.
| |
| 2 And at our Wingspread meeting the Europeans 3 pointed out to us that one of the major problems was the 4 fact that instead of the various countries observing what 5 they had agreed on as protective action guides, they set ad 6 hoc lower, reduced action guides, and I think confusion such 7 as different action guides for Canada and the U.S. would 8 quite likely lead rapidly to this kind of chaos.
| |
| 9 So to me that is an important aspect.
| |
| 10 Another item was that they did use KI, yet here 11 in the United States we allow each state separately, 12 individually to make the decision on what action level do 13 you administer KI or do you use it at all. Again, that is 14 inviting chaos.
| |
| 15 We need to have a national policy, I would think, 16 on KI, or at least NRC ought to encourage us to have a 17 national policy.
| |
| 18 Ane her interesting thing to me from Chernobyl --
| |
| 19 and maybe it is obvious -- was that ingestion did not prove 20 to be of any consequence whatsoever as far as any acute 21 effects are concern + !, and we probably knew that. But I 22 think the fact that t accident clearly pointed it out is 23 rather important.
| |
| 24 DR. REMICK: Dade, when you say " ingestion," you
| |
| , 25 modn --
| |
| ,f ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage 84tv336-6M6
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| 2071 07 11 90 DAVbur 1 DR. MOELLER: Eating or drinking.
| |
| 2 Breathing might have been inhalation, although I 3 am not sure that inhalation -- we would have to check that, 4 but I am not sure that inhalation --
| |
| 5 DR. REMICK: I think it did on some of the 6 firefighters.
| |
| 7 DR. OKRENT: Ingestion is a problem.
| |
| 8 DR. MOELLER: Long-range, absolutely. But I 9 think there is a lesson there, and then, lastly, in reading 10 your material, of course you pointed out that in the USSR 11 the military played a major role in helping, I gather, with 12 the evacuation even and other protective measurec, or 13 certainly in decontamination.
| |
| 14 I would imagine that our military could probably 15 be useful and beneficial, and I would think, therefore, that 16 on a national scale when we are thinking about emergency 17 preparedness we ought to incorporate DOD into our thinking 18 and find out what they might be able to do with us or for 19 us.
| |
| 20 MR. SHARON: I think Shelley Schwartz from I&E 21 would like to make some comments.
| |
| 22 DR. SCHWARTZ: On your first point, on the 23 conscious need to compare action guides, that is an area 24 I that I don't think really fits into the post-Chernobyl 25 look. It is one that we were working on and discussing with ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage 80lk33W
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| 2071 07 12 91 DAVbur 1 Canada pre-Chernobyl for the plants close to the border. So 2 we understand what kind of actions would be taken.
| |
| 3 In fact, I understand that the Fermi reactor has 4 good relations with their counterparts across the border, 5 and they have been working --
| |
| 6 DR. MOELLER: To try to get uniform measures.
| |
| 7 DR. SCHWARTZ: It will take a federal effort to 8 work with their counterparts in Canada to decide with one 9 where we should have the same PAGs or to at least understand 10 the differences.
| |
| 11 I am not sure in the scheme of things if we will 12 ever drive Canada or Canada would drive us to assuming that 13 we are going to have the same PAGs, but it is an issue, and 14 we are continuing our discussions with them.
| |
| 15 DR. MOELLER: All of this, as I keep playing a 16 broken record, ties into the revision of 10 CFR 20 and ICRP 17 26.
| |
| 18 DR. KERR: Do the protective action guidelines in 19 Canada say that they would take action on a higher level or 20 a lower level?
| |
| 21 DR. SCHWARTZ: I don't know what those numbers 22 are.
| |
| 23 With recpect to the policy on KI, the federal 24 government does have a policy on KI. It has allowed the
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| ~
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| ( ', 25 states to make their own decision with respect to
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| ACE-FEDERAL REPORTERS, INC.
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| 2071 07 13 92 DAVbur 1 stockpiling predistribution of KI.
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| 2 The federal government provided the information 3 to the state and local governments and a cost / benefit 4 analysis of stockpiling with respect to KI and came down on 5 the side that it was not a federal requirement that it be 6 stockpiled.
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| 7 8
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| 9 10 11 12
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| - 13 15 16 17 18 19 20 l 21 22 23 24 25 (O.)
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| 071 08 01 93 1 DAVbw 1 There are some six states now that have pre 2 plant. Two come to mind now. One is Tennessee, and they do 3 predistribute, and I understand Alabama does stockpile.
| |
| 4 DR. MOELLER: Yes. We had a report from the 5 Director of Emergency Planning in Alabama. If an accident 6 occurs, the first thing is, you drive into the local town 7 and go by the city hall, pick up your KI bills. Then you go 8 back and evacuate.
| |
| 9 (Laughter.)
| |
| 10 DR. MOELLER: Do we have -- and obviously, we do, 11 from what you said, have a table for each state and where it 12 stands on its KI policies?
| |
| 13 DR. SCHWARTZ: I don't have that table, but the 14 Federal Emergency Management monitors the off-site 15 consequences, the off-site planning, and we can certainly 16 ask them to provide us with such a table.
| |
| 17 DR. KERR I Lhink that raquires a little bit of 18 explanation. I don't know whether you have some relative in 19 Alabama oc they move more slowly in Alabama than in other 20 states, and people have the time to go and get the KI pills 21 and go back and evacuate before the accident becomes more 22 serious.
| |
| 23 DR. SCHWARTZ: The point you make, Dr. Moeller,
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| '~
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| 24 is the point we are all concerned about. Should there be 25 distribution or stockpiling. Particularly stockpiling with ACE-FEDERAL REPORTERS, INC.
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| 071.08 02 94 1 DAVbw 1 a shelf life. How long would it be good, and then how you 2 distribute it after an accident?
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| 3 Tennessee made the decision that they would 4 predistribute to the folks around the facility, and I take 5 it at Sequoyah, they've gone around and done it twice now 6 over the years to make sure they had it.
| |
| 7 It was their decison.
| |
| 8 DR. MOELLER: In addition to whether you agree to 9 distribute or stockpile, there is the question at what 10 projected dose should it be administered. To me, that would 11 be helpful, if NRC or FEMA hesitate to do something like 12 this, the NRC does provide supporting funds, say, in the i
| |
| 13 NCRP. You might ask them to independently assess, evaluate 14 and make some recommendations. That would be a way, you 15 know, to get it done. j 16 DR. SCHWARTZ: That is a good suggestion, because 17 the medical community, as you know, is discussing it on both 18 sides. I think it is an excellent suggestion.
| |
| 19 DR. REMICK: As far as stockpiling and 20 distributing relate to the general public, the NRC does have 21 a policy for plant workers.
| |
| 22 DR. SCHWARTZ: Thank you. There is a policy to 23 assure that plant personnel can have stock piles for their
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| ' 'n, 24 use, in case of an accident.
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| .)
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| 25 The last point I would like to make, if I may is, ACE-FEDERAL REPORTERS, INC.
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| 1' 071 08 03 95 1 DAVbw 1 as far as the military, we ought to fathom the military 2 capability, in case we have this type of thing in the United 3 States. I contend that we essentially do have that kind of 4 tie-in through the Federal Radiological Emergency Planning 5 program, where, in the event of an accident, they would put 6 together what we call a federal response center, where all 7 the agencies who are responsible for radiological response 8 will be there and, in fact, even before this, I remember, at 9 one point in time -- and this was back at the TM1 event, 10 when there was need for military transport to bring some 11 people to the site and that happened, I believe the
| |
| --- 12 resources there and the question as to whether we need to 13 detail that capability is still an open question. But 14 certainly, the transportation and personnel and manpower 15 aspects are available at the federal level.
| |
| 16 DR. MOELLER: Well, to know what that might do to 17 assess an evacuation and to know what they might do in 18 washing down streets or things.
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| 19 DR. SCHWARTZ: Sure, when the governor gets 20 involved, the first thing he is going to do is, he is going 21 to call out his own national guard, which he uses in all 22 those types of emergencies, and bring them into play as 23 well.
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| ^
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| 4 24 DR. MOELLER: Thank you.
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| 35 DR. SCHWARTZ: Thank you.
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| 071 08 04 96 1 DAVbw 1 MR. WARD: Dade, on the subject of KI 2 distribution, this question came up at the subcommittee 3 meeting. The Soviets apparently distributed, I don't know, 4 100,000, a couple of hundred thousand doses of KI. Their 5 contention was that there were no adverse reactions.
| |
| 6 Is that reasonable?
| |
| 7 DR. MOELLER: Well, I presume it was one of our 8 first major mass tests of that. The medical profession does 9 tell us that what is it, 1 percent or something of the 10 population will have an adverse reaction, and then, though I 11 asked what is the adverse reaction, you know, I asked 12 several M.D.s, and if my memory is correct, it is not all 13 that bad. They might be ill for a short period of time.
| |
| 14 DR. KERR: My impression was that the Russians 15 didn't say they didn't have any adverse reactions. They 16 said they didn't have any toxic reactions. Maybe that is my 17 memory of the language.
| |
| 18 DR. SCHWARTZ: I don't mean to be argumentative, 19 but I think the words that I heard were no adverse 20 reactions, but I will go back and check.
| |
| 21 DR. LEWIS: I think that 1 percent number was 22 people who had allerg,, reactions, and then there is a 23 smaller percentage who may have serious ones. I don't
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| ^'
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| 24 remember the numbers, but there are small numbers.
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| ()
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| 25 DR. SHARON: The last area is under the general ACE-FEDERAL REPORTERS, INC.
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| 1 am.m s _ m r _ ,. --
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| 071 08 05 97 1 DAVbw 1 heading, Severe Accident Phenomena.
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| 2 Again, because of the uniqueness of the accident 3 itself, there was a mechanical dispersion, not a meltdown, 4 which we calculate over here for severe accidents. I think 5 the only conclusions that we drew is that, one, a, we have 6 to recognize that this plan did have a mechanical dispersal 7 mechanism, and with regard to analyzing severe accidents 8 here, I think we just have to always keep in mind that if 9 one does add enough energy deposition in the fuel, that one 10 can, indeed, get a mechanical dispersal mechanism.
| |
| 11 We shouldn't lose sight of that.
| |
| 12 DR. OKRENT: There are other ways of getting
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| ~'
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| 13 mechanical dispersal mechanisms for lightwater reactors, 14 besides a reactivity excursion.
| |
| 15 MR. SHARON: Through steam explosions, for 16 example.
| |
| 17 DR. OKRENT: If the containment goes first, then 18 you get not too big a steam explosion. It is a dispersal 19 mechanism.
| |
| 20 MR. SHARON: I think that is what we are really 21 trying to say, is that one has to recognize that there are 22 mechanical dispersal mechanisms.
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| 23 The second one is that we noted that the chemical
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| ^
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| 24 stripping effusion products from fuel particle surfaces did 25 occur via oxidation of the fuel to U308. I think it is just ACE-FEDERAL REPORTERS, INC.
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| 071 08 06 98 1 DAVbw 1 something we have to keep in mind when we go through the 2 source term evaluation.
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| 3 The last area that I will talk about, and this is 4 a new one which we added --
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| 5 (Slide.)
| |
| 6 -- is the implication of Chernobyl moderated 7 reactors in the U.S. There's a number of graphite moderated 8 reactors in the U.S. either in operation or contemplated.
| |
| 9 The Port St. Vrain HTGR out in Colorado is the only 10 operating commerical gas-cooled reactor, graphite moderated 11 gas-cooled reactor in the United States.
| |
| 12 There is the DOE reactor in Hanford, which I 13 am not going to talk about, because we have not evaluated 14 that. DOS is doing that. It is their responsibility.
| |
| 15 I would point out that research programs that DOE 16 is sponsoring on graphite reactors that might be applicable 17 to the DOE reactors, we are certainly trying to take that 18 data and use it as best we can. In other words, we are 19 trying to benefit from their research on their 20 graphite-moderated reactors, but we have not specifically 21 looked at any implications of Chernobyl on their reactors.
| |
| 22 The only other one that is, I guess, of some 23 interest is that DOS, in their advanced reactor program, is
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| '~ 24 proposing a modular HTGR as a concept; however, that is in 25 such early stages of design, that we really didn't want to ACE-FEDERAL REPORTERS, INC.
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| 202-347-370 Nationwide Coserage AtF336-tM6
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| 071 08 07 99 2 DAVbw 1 go in and do a complete impact assessment at this time on 2 that reactor.
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| 3 So I am going to talk mostly about the Fort 4 St. Vrain.
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| 5 We took a look at Fort St. Vrain and its design.
| |
| 6 Number one, we could not come up with any design 7 weaknesses that had a nexus or basically derived from the 8 Chernobyl accident, albeit it they both use graphite as a 9 moderator. I think that is about where the similarity 10 ends.
| |
| 11 As you know, Fort St. Vrain uses inert helium as 12 a coolant. They don't have the oxide core. They have a
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| ~
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| 13 ceramic core. The fuel particles are encased in -- what is 14 it, Peter, a silicon?
| |
| 15 MR. WILLIAMS: Silicon carbide is one of the 16 major barriers. There are pyrolitic graphic layers also.
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| 17 MR. SHARON: It doesn't use water, so we don't 18 get the steam.
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| 19 Dr. Okrent?
| |
| 20 DR. OKRENT: It has a steam generator, and if you I
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| 21 l; had a gross rupture of the steam generator, you could have i
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| 22 i water ingress into the core pressurization, hydrogen 23 generation, a variety of things that are not on your list.
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| 24 MR. SHARON: We fully recognize one can get water 25 ,
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| ingress into these bores and add reactivity by virtue of ACE-FEDERAL REPORTERS, INC.
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| mmmm xe - ~ , -
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| 071 08 08 100 1 DAVbw 1 adding water.
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| 2 This is an undermoderated reactor. Chernobyl was 3 an overmoderated reactor, so that adding water will increase 4 the reactivity.
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| 5 DR. OKRENT: It can do more than that, but in any 6 event, the reactor happens not to have a containment. If 7 you don't call the PCRV a containment, and I don't think you 8 c a r..
| |
| 9 MR. SHARON: I understand that was a subject of 10 debate some years ago.
| |
| 11 I would just point out, it has a pressurized 12 concrete vessel around it. Some people consider that to
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| ~
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| 13 perform the containment function. There's a steel liner 14 inside of the vessel, and again, the access to the vessel 15 itself -- I shouldn't say the vessel, but the access 16 hatches, there's two places, one on the bottom and one on 17 the top.
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| 18 MR. WI LLI AMS : They call them penetration.
| |
| 19 Penetration closures, and as I am sure you know, they are 20 double penetration closures. These are monitored, 21 constantly monitored, I think you are well aware.
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| 22 DR. OKRENT: I am well aware. I was there when 23 Fort St. Vrain was opened.
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| 24 MR. SHARON: Anyway, we looked at the potential 25 for fire in the core. In order to get a fire, one would ACE-FEDERAL REPORTERS, INC.
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| 071 08 09 101 1 DAVbw 1 have to have both of these penetrations fail, so that one 2 could get the air in and get the circulation to keep the air 3 flow in and out from the bottom to the top.
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| 4 It was looked at. The Fort St. Vrain people said 5 that in the event that they had the unlikely failure of both 6 penetrations, so that they actually got that condition, they 7 could flood the lower compartment up, so that they could 8 seal off that lower penetration and, therefore, stop any air 9 going into the core, so they could turn off the fire, 10 basically, by starving it of air, if they had to.
| |
| 11 We did not see any new concerns relative to the 12 severe accident phenomena that might be associated with an 13 HTG3r however, I think it did emphasize and point out to us 14 a couple of things. One is, that Fort St. Vrain doesn't 15 have a PRA, and we certainly think one would be desirable, 16 particularly if the plant is going to continue to operate.
| |
| 17 I know there is some question right now. Mark, 18 do you think it would make it safer?
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| 19 MR. SHARON: No, I think it would help us 20 understand the relative level of risk. I would point out 21 that Fort St. Vrain will come under the Commission's severe 22 , accident policy implementation program. We anticipate that i
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| 23 ' they will receive a letter saying that they have to do plant 24 specific vulnerability examinations like everybody else.
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| - i 25 l They would obviously not be able to use the methods ACE-FEDERAL REPORTERS, INC.
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| l 202-347-3700 Nationwide Cos erage 8 0-336-6646
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| r-071 08 10 102 1 DAVbw 1 developed by the IDCOR people, so they would have to do 2 something that was applicable to their plant.
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| 3 DR. SIESS: I thought we had done something 4 similar to a PRA some years ago. Accident progression 5 initiation or something else.
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| 6 MR. WILLIAMS: Peter Williams, NRC Staff.
| |
| 7 There have been a number of PRA studies. There 8 have also been some very limited PRA studies of Fort 9 St. Vrain, both on design basis accidents, pressurization 10 accidents a.id the core heat-up accident, have been analyzed 11 by PRA. There is a good background for performing a PRA on 12 gas-cooled reactors, but there really has been no formal one 13 for Fort St. Vrain.
| |
| 14 MR. SHARON: Lastly, we are interested in graphic 15 thermal stress experiments, which would be helpful in 16 understanding the performance of the graphite blocks under 17 strong thermal stresses. One can get very high thermal 18 gradients in these cores, because the graphite has such a 19 high heat capacity. The coolant cools down very quickly.
| |
| 20 The graphite stays at high temperature, and you get strong 21 gradients across the graphite, and I suppose, if these got l
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| 22 l strong enough, you could actually induce breaking up of the 23 l graphite.
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| /~' 24 Then the question is, what happens the? I a
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| 25 believe, is it DOE that is doing some of this, Peter?
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| 071 08 11 103 1 DAVbw 1 MR. WILLIAMS: Some years ago, as a result of 2 some calculated thermal stresses in the course of the work 3 plans, our research organization sponsored a study at Los 4 Alamos on graphite thermal stress. They have done work on 5 the type of material that makes up the graphite posts. The 6 consideration is to extend this study into the PGX graphite, 7 which is material that is used in the core support fuel.
| |
| 8 MR. SHARON: This is our other conclusion, that 9 we would certainly encourage these experiments to go 10 f o rwa rd .
| |
| 11 That concludes my presentation on the 12 implications. As I said, we are right now in sort of a a
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| 13 clean-up mode with the report.
| |
| 14 We want to just clean it up, make sure that we've 15 dotted all the "i's" and crossed all the "t's" on it. We 16 would certainly lock forward to getting a letter from the 17 ACRS. Favorable would be better than not favor.ble.
| |
| 18 And again, we would like to get this package 19 together, so it can be published sometime in January, and we 20 would like to go to the Commission with these implications 21 and get their blessings on them right now for the week of 22 J anuary 19th.
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| 23 If there's any other questions, I'll be glad to 24 try and answer them or Staf f here can.
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| 25 DR. REMICK: There were several questions that ACE-FEDERAL REPORTERS, INC.
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| I' - ,m_ m c- 8- r
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| ~ -
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| 071 08 12 104 1 DAVbw I came up in the subcora:nittee meeting.
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| 2 One, Dr. Lewis raised the question of whether, 3 under your discussion of tests and a comparison of the 4 U.S. of unreviewed tests, whether there was consideration of 5 surveillance testing in that section, and whether 6 surveillance tests were perhaps conducted too frequently.
| |
| 7 I was wondering if the Staff has made any 8 consideration of that.
| |
| 9 The other topic was one, the wording emphasized, 10 the licensed operators. And there was discussion of, aren't 11 you really talking about plant personnel beyond licensed 12 operators.
| |
| 13 !*as the Staff given any additional consideration 14 to that?
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| 15
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| ~_-
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| 17 18 19 L
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| 20 21 22 23 3 24
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| 25 ACE-FEDERAL REPORTERS, INC.
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| 071 09 01 105 1 DAVbur 1 MR. SHARON: I will apologize because I was out 2 of the office all day yesterday. So I haven't had a 3 chance.
| |
| 4 My guess is that there has been nothing formally 5 done, but we have made note of it, and I think it is 6 something we will want to consider and try to include, as I 7 said, as part of the final report writeup, to take into 8 account the concerns that were raised by the ACRS 9 subcommittee as well as the full committee and work them 10 into the writeup. j 11 These two areas would certainly be two that we 12 would want to consider.
| |
| 13 One, I will just repeat, was the surveillance 4 l 14 testing. There was a question raised by Dr. Lewis. They i
| |
| 15 were running a test at Chernobyl, and there is a concern 16 that sometimes we run tests just for the sake of running 17 tests and we may do more harm than good.
| |
| 18 I think we acknowledae that was certainly a 19 legitimate observation.
| |
| 20 As you know from the diesel testing and the 21 people who have complained about the fact that when you 22 require a fast start test it may do more harm than good, I 23 think it is an area that we have to take a look at in terms
| |
| ] 24 of what is the optimum type of testing from a safey 25 standpoint.
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| ACE-FEDERAL REPORTERS, INC.
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| 1 071 09 02 106 1 DAVbur 1 It is a difficult question, but I don't think it 2 is one we should just put aside and say it is too tough to 3 answer.
| |
| s 4 DR. OKRENT: I was under the impression from 5 Chernobyl that they were not doing surveillance testing, 6 that they were doing something very different from 7 surveillance testing.
| |
| 8 MR. SHARON: They were doing what typically, I 9 think, we would have required as a startup test. In other 10 words, they were trying to demonstrate that their safety 11 system worked as designed.
| |
| 12 DR. OKRENT: I will buy that, but not 13 surveillance testing.
| |
| 14 MR. SHARON: No. It just brought to light that 15 they were doing a test because they were required to do a 16 test and because if they were doing a test it brought about 17 an accident.
| |
| 18 Now, that is not saying that that was bad. It is 19 certainly a matter -- it raises an issue that I think we l
| |
| l 20 would want to explore a little bit more and say, as an 21 implication should we go off and study this or do some more 22 work in this area or their ongoing programs, for example. j l
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| 23 DR. REMICK: I might have mischaracterized what l
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| (' , 24 l Dr. Lewis was talking about by calling it surveillance 25 testing. I am not sure you limited it to surveillance ACE-FEDERAL REPORTERS, INC.
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| r-071 09 03 107 1 DAVbur 1 testing when you were talking about unnecessary testing.
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| 2 DR. LEWIS: No. We agreed on that yesterday.
| |
| 3 Just the general question of they were indeed not doing 4 surveillance testing; they were doing a demonstration test 5 to in a sense relieve themselves from regulatory 6 requirements.
| |
| 7 That is what they were doing. They were trying 8 to evade a regulatory requirement for fast start of their 9 diesels.
| |
| 10 But it just raised in my mind the whole question 11 because there exists a theory of reliability that you can
| |
| --3 12 exploit to some extent to give you reasonable testing 13 intervals, and my question was not quantitative, but because 14 of the fact that I have seen so many things happen as a 15 result of surveillance testing, then I wanted to know how 16 long it has been since it has been revisited.
| |
| 17 DR. OKRENT: I have no problem with looking at 18 surveillance testing, but at the beginning we heard that 19 they weren't going to try to look for things that people 20 were interested in that didn't have some connection with 21 Chernobyl.
| |
| 22 In fact, it was not even clear to me that they 23 were doing a test to avoid a requirement. I didn't think
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| '" 24 their diesels could start that fast.
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| m--
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| 25 DR. KERR: I don't think ours can either.
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| ACE-FEDERAL REPORTERS, INC.
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| -- x _ m- -- I
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| 7 071 09 04 108 1 DAVbur 1 DR. OKRENT: That may be.
| |
| 2 MR. SHARON: No, they weren't. They did not have 3 a requirement for the diesels to start fast. They had a 4 requirement, though, that they had to keep the core covered 5 and not go critical.
| |
| 6 DR. OKRENT: Which they had trouble meeting?
| |
| 7 MR. SHARON: As a matter of fact, the first test 8 they ran showed that their system didn't work as designed, 9 and they performed a modification, and that was what this 10 test was about, to demonstrate the modification and fix the 11 problem.
| |
| 12 DR. MARK: Look, this is a question out of total 13 ignorance.
| |
| 14 I believe the N reactor has water and graphite.
| |
| 15 If the only immobile element is the water, if the water is 16 voided, the reactivity at N reactor goes down, is that 17 right?
| |
| 18 DR. OKRENT: Correct.
| |
| 19 DR. LEWIS: So I am assured.
| |
| 20 DR. MARK: And that is masked by using the word 21 "under-moderated"; whereas, Chernobyl was over-moderated.
| |
| 22 When the water got out, reactivity went up.
| |
| 23 I think there is a more comprehensible way of
| |
| (', 24 saying that than using the words "under-moderated" and
| |
| ' J 25 "over-moderated," that we have graphite at Fort St. Vrain.
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| ACE-FEDERAL REPORTERS, INC.
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| 21C-347-37(X) Nationwide Contrage m> 336-6a6
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| 071 09 05 109 1 DAVbur 1 There, if the coolant, the mobile element, goes 2 out, nothing happens.
| |
| 3 DR. OKRENT: A few cents of reactivity.
| |
| 4 DR. MARK: Very few, and there is a really 5 integral, crucial difference between us and Chernobyl, and 6 it should, in my view, come out more clearly if said that 7 way.
| |
| 8 DR. LEWIS: I personally believe the lessons of 9 Chernobyl are really not hardware lessons. They are 10 management lessons.
| |
| 11 DR. MARK: There's lots of lessons. I don't mean 12 there is no relevance, but there is a total black and white 13 difference between Chernobyl and the reactors we are talking 14 about that have graphite in them.
| |
| 15 DR. OKRENT: I wonder if I could ask the members 16 if they have additional points to be covered in a possible 17 letter. There is no decision on whether to send a letter on 18 Chernobyl. I guess we have to.
| |
| 19 If they have additional points on a letter -- for 20 example, the current one doesn't mention Fort St. Vrain. Do 21 you think something should be there in that regard?
| |
| 22 I would appreciate either receiving a paragraph 23 -- if not, at least a cryptic statement -- telling me what r~ , 24 should be in the paragraph in your opinion, so I can try to 25 have sometning that at least includes for review the points ACE-FEDERAL REPORTERS, INC.
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| 2[I2-347-37(E) N.llion% nde CO%Crage 81Mk 3 W(/M
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| 071 09 06 110 2 DAVbur 1 that members....
| |
| 2 We are out of time now.
| |
| 3 DR. REMICK: My only point on the letter is I 4 think we want to keep it.
| |
| 5 If the staff has omitted something or said 6 something incorrectly or not clearly, we ought to address 7 that. But I am not sure we should just put in statements 8 and not know whether the staff has addressed that adequately 9 or not.
| |
| 10 I guess I am feeling that in drafts there are 11 statements which the staff already has made in their 12 document. I am not sure we need to address it. We should 13 be able to look at it from that standpoint.
| |
| 14 There ought to be some correlation between what 15 we said and what staff said.
| |
| 16 DR. OKRENT: There might be.
| |
| 17 Anyway, we are beyond your allotted time, 18 Mr. Chairman, and we normally had left 45 minutes for 19 discussion.
| |
| 20 MR. WARD: I think the discussion occurred as we 21 went along.
| |
| 22 DR. OKRENT: Anyway, I am going to ask again that 23 members get me either paragraphs or identify specific items 24 that they would like to see paragraphs on by 5:00 o' clock
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| (~'
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| 25 today.
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| ACE-FEDERAL REPORTERS, INC.
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| 071 09 07 111 2 DAVbur 1 MR. WARD: Let's come back at 1:50.
| |
| 2 (Whereupon, at 12:50 p.m., the committee was 3 recessed for lunch, to reconvene at 1:50 p.m., this same 4 day.)
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| 5 6
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| 7 8
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| 9 10 11 12 7
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| 25 ACE-FEDERAL REPORTERS, INC.
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| 071 09 08 112 1 DAVbur 1 AFTERNOON SESSION 2 (1:55 p.m.)
| |
| 3 MR. WARD: Our next topic is discussion of 4 containment performance.
| |
| 5 Dr. Mark.
| |
| 6 DR. M ARK : This is hardly containment performance 7 in the broadest sense. I believe what we will talk about 8 are the concerns that have been raised in connection with 9 the Mark I boiling water reactor containment.
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| e 10 I don't think we will reach any other item on 11 this.
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| 12 We had a meeting on Tuesday. I have forgotten
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| (
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| * 13 just who was there. There were three of us -- Bill Kerr, 14 Charlie Wylie, and who else?
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| 15 MR. BERNERO: Ebersole and Michelson.
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| 16 DR. MARK: We had a meeting of the subcommittee, 17 which heard mainly from Bob Bernero on his proposal for a 18 radical immediate fix on BWR Mark 1 systems.
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| 19 We had in front of us notes from Dave Okrent and i
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| 20 Commissioner Asselstine supporting the idea that something 21 should be done.
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| 22 I am corry, did I misrepresent you, Dave?
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| 23 DR. OKRENT: Correct. I said something should be 24 done.
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| 25 I was not specifically supporting an A through E ACE-FEDERAL REPORTERS, INC.
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| I 202-347-3700 Nanonwide Cos etage MXK 3.16-%46
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| 071 09 09 113 1 DAVbur 1 or 1 through 6.
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| 2 DR. MARK: Anyway, we had this meeting and we 3 will have a presentation from Bernero this afternoon giving 4 the gist, I believe, of what he has felt to be clear, and we 5 are being asked to make some comments either for his 6 proposals or against them in the course of this meeting 7 because his suggestions are going to reach CRGR in the 8 course of 10 days and the Commission is going to make a 9 decision on them 10 days after that.
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| 10 MR. BERNERO: And presumably so am I.
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| 11 DR. MARK: That is, I think, where we stand.
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| 12 What Bob is proposing he will tell us. He will give us some 13 notions of his estimates of the need for this, the effects 14 of this, and the cost of this because what he is proposing 15 will have some cost and will be based on some need.
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| 16 I think at that point, Mr. Chairman, unless you 17 have something urgent, I will turn the floor over to him.
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| 18 We do have here Mr. Pickens, I think, of the BWR 19 OG, the boiling water reactor owners group, who will have 20 some things to say which are not, I believe, totally 21 orthogonal to what Bernero is saying.
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| 22 Please, Bob.
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| 23 (slide.)
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| em 24 MR. BERNERO: All right, Mr. Chairman, the topic 25 here is a proposal via the form of a generic letter for some ACE-FEDERAL REPORTERS, INC.
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| -- x_ m r- --
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| 071 09 10 114 1 DAVbur 1 severe accident issue corrections or problem corrections in 2 one type of U.S. containment.
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| 3 The Mark I containment is' singled out in this 4 action in the draft generic letter. You have seen in its 5 analysis it indicates that the other boiling water reactor 6 pressure suppression containments lend themselves to the 7 same treatment, albeit with slightly different 8 requirements.
| |
| 9 The same can be said for other containments as 10 well, PWR containments, so that this model of action that I 11 propose I would also encourage people to think in terms of 12 applying it to other containments as well as the Mark I.
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| 13 The Mark I has been selected out of our group 14 because of its priority. It is the largest in population, 15 24 containn:ents, all licensed, and they are often singled 16 out as the most difficult to analyze or to accept in a 17 severe accident phase.
| |
| 18 Just to refresh your memory, you recall that the 19 NRC put out the severe accident policy August 8th of 1985.
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| 20 After a good deal of controversy, the Commission did say 21 present reactors are safe enough, but -- and the "but" --
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| 22 ' the mortgage for existing reactors is that a: long as you 23 know you don't have any outliers, s ig n i f ica r.t 24 vulnerabilities to severe accidents that might be plant 25 specific in character. And the Commission did also indicate ACE-FEDERAL REPORTERS, INC. !
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| :~.u-,
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| ~ ~ c- ._
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| 1 i
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| i Ah071:09 11- 115
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| - : 1 lw /
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| 1- DAVbur :1 its desire to consider the balance of prevention and 2 mitigation, the concept of defense in' depth in/ dealing with 3 the search for. outliers, and special consideration of-4 containment' performance'was identified, whatever that 5 meant.
| |
| '6 (Slide.)
| |
| 7 The' search for outliers, we are really looking 8- for a'significant vulnerability.- This is not really an 9 objective to quantify inliers; in other words,' to come up 10 with a precise description of the accident frequency 11 distribution in a reactor.
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| f- _
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| 12 The objective is more in terms of finding a
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| : 13. something that is outside the pale that is a significant 14 contributor to risk.
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| 15 The expected theme that the severe accident F.
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| ; 16 policy statement shows is that unless you have already done
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| ! 17 it through the form of an extensive PRA, or something like h -18 that, unless it is already done there should be a plant 19 specific evaluation to identify the outliers and to backfit i
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| j 20 as appropriate.
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| 21 The Commission takes pain to say consistent with 22 the backfit policy and rule, where now the policy statement 23 goes on to say where the technical issue goes beyond current 24 regulatory requirements generic rulemaking is preferred.
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| }
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| ; 25 But the policy statement recognizes alternate 1
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| i
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| l ACE-FEDERAL REPORTERS, INC.
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| M-347-3700 Nationwide Coserage 800-336 6M6
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| 071 09 12 116 1 DAVbur 1 instruments, such as bulletins, orders, or generic letters.
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| 2 It is rather interesting that the statement was 3 made -- where it goes beyond current regulatory 4 requirements --
| |
| 5 (Slide.)
| |
| 6 -- because if you look with respect to 7 containment at the two key design criteria for containment, 8 Criterion 16 on containment design and Criterion 50 on 9 containment design basis, they have within them the words 10 that indicate that severe accident performance, core melt 11 performance of a containment is indeed beyond the design l
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| 12 basis, an essentially leak-tight barrier against the 13 uncontrolled release of radioactivity for as long as 14 postulated accident conditions require.
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| 15 It is a clear tie and has been over the years a 16 clear tie back to the design basis accident, general design 17 Criterion 50.
| |
| 18 The criterion goes on -- of course, it is much 19 longer than this, but the key words are conditions that 20 result from degradation but not total failure of emergency 21 core cooling functioning.
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| 22 Again, the design basis accident postulates t
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| 23 ! certain degraded conditions, single failures, things of that I
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| r~~ s 24 l sort, but it does not enter the land where no cooling at 1
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| 25 all, where core melt prevails.
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| ACE-FEDERAL REPORTERS, INC.
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| m u>a,- s_ m m- ,_ i
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| 071 09 13 117 1 DAVbur 1 DR. MARK: Bob, a comment. If the Commission 2 issues a rulemaking -- which of course takes forever -- then 3 that is law. That has to be adhered to.
| |
| 4 If the Commission forwards a generic letter, is 5 that or is that not law?
| |
| 6 MR. BERNERO: It doesn't have the same stature as 7 the Commission regulation, which has the force of law.
| |
| 8 Nonetheless, it is a requirement imposed by staff, not the 9 Commission.
| |
| 10 The Commission does not issue generic letters.
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| 11 Staff does, and the staff frequently resorts to this
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| -, 12 instrument to obtain detailed implementation of things --
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| 13 hydrogen control, details of containment atmosphere dilution 14 systems, things of detailed interpretation.
| |
| 15 DR. MARK: Supposing I am a utility, and I feel 16 very negative to you, Staff, and you issue a generic letter 17 and I say some unutterable word, what then? I 18 MR. BERNERO: First of all, I don't know if 19 anyone has ever done it, but if they did, the staff can 20 issue an order. The staff has the authority to order you to 21 do something, and then you are citable, and that is 22 enforcible. That is clearly enforcible.
| |
| 23 DR. MARK: That sounds to me like law.
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| 24 MR. BERNERO: I believe it is. I can't really
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| )
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| 25 tell you. I know a generic letter is citable and ACE-FEDERAL REPORTERS, INC.
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| X 202-347 3'00 Nationaide Cos crage Nn 3 Ef6M
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| l l
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| l 1
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| 071 09 14 118 al.-DAVbur 1 enforcible. People do it. But whether it has'the force of 2 law, that phrase I would have to defer to legal counsel..
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| 3~ DR. REMICK: I am not sure it has the force of e 4 law, but I think what you are referring to is if staff is in f 5 that situation they can issue -- 'the Coramission could issue 6 a show cause letter, saying you show us cause why we 7 shouldn't shut you down because you haven't done this, and t
| |
| 8 that gives the licensee an opportunity to come back and I
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| 9 argue his point, where he would request a hearing.
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| 10 DR. MARK: But it would be settled finally by the 11 Commission.
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| 12 O 13
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| '14 15 i-16 17
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| ; 18 19 J
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| <- 20 21 22 j-4' 23
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| , - 24 i- 25 ACE-FEDERAL REPORTERS, INC.
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| ! 202 347 3700 Nationwide Coserage NXF336-6M6
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| 071 10 01 119 1 DAVbur 1 MR. BERNERO: The Commission doesn't have to. If 2 they come back and don't have a good reason for not 3 implementing the letter, then the license can be amended to 4 require it. There can be order. There are legal 5 instruments that are available at the staff level.
| |
| 6 DR. MARK: I really don't want to take this very 7 seriously, but you are using the route or talking here about 8 the route of a generic letter rather than a rulemaking, in 9 part at least because it is something that would be seen to 10 happen in the next year or so, whereas the other could not.
| |
| 11 MR. BERNERO: One is time, the other is 12 character. The character of the action where one speaks of 13 specific pipe sizes, event sizes, power supplies lends 14 itself far better to a generic letter than the statesmanlike 15 proceedings of a rulemaking, although sometimes we have had 16 very prescriptive rules.
| |
| 17 The important point I was trying to make is we 18 are beyond the regulations.
| |
| 19 (Slide.)
| |
| 20 In the generic letter draft which you have, there 21 is a hard to read table. I don't expect you to read this on 22 i the board, but I want to single it out.
| |
| 23 It is a listing of the PRA results and sample
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| ~'
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| 24 individual plant evaluation results. That is what the IPE I
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| 25 here stands for.
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| ACE-FEDERAL REPORTERS, INC.
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| 202 147 3700 Nationuide Coserage 80lL 346M6
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| 071 10 02 120 2 DAVbur 1 The results we have of the analysis to date of 2 boiling water reactors and a key parameter -- and this is a 3 very good point that came out in Tuesday's meeting with the 4 subcommittee -- the last column -- we have here core damage 5 frequency in this column here, but the last column is 6 containment conditional failure probability.
| |
| 7 There is a sloppiness of language that has grown, 8 and we are struggling with it. If you analyze in a risk 9 analysis a single accident sequence, TMLB-prime, station 10 blackout, or an ATWS of some type or other, you do a 11 containment event tree and analyze the outcome, the
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| ~
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| 12 probability of different outcomes, and from that containment 13 event tree analysis you can derive a conditional 14 probability.
| |
| 15 Given accident sequence X, what is the 16 conditional probability of containment failure?
| |
| 17 First of all, you have got to be careful.
| |
| 18 Containment failure shouldn't really be loss of leak 19 tightness because a successfully vented, filtered pressure 20 relief is not a failure, or I wouldn't define it as a 21 f ailu re.
| |
| 22 Failure ought to be a large release or a 23 relatively large release that the containment didn't provide
| |
| ^1 24 substantial mitigation.
| |
| 25 So that if you look at containment failure as a ACE-FEDERAL REPORTERS, INC.
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| m m.,- s- . - --
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| 071 10 03 121 1 DAVbur 1 relatively large release, for a given accident sequence you 2 have a conditional probability.
| |
| 3 For a given plant you have a family of accident 4 sequences, each with its own probability, and if you take a 5 weighted average of those conditional containment failure 6 probabilities, you have something you might call the 7 fraction of core melts for that plant that can be expected 8 to result in a large release, and that is really what we are 9 talking about, the overall success or failure rate of 10 containment.
| |
| 11 MR. WARD: Is that what that last column is?
| |
| 12 MR. BERNERO: That is what we are trying to make 13 it be.
| |
| 14 DR. MARK: Would you define a large release in 15 terms of the number of curies or the number of rems at the 16 plant boundary?
| |
| 17 MR. BERNERO: No. That is going to make it very 18 difficult. Of course, there is a lot of debate and source 19 term space about how large is large. What do you get if you 20 have an unmitigated release?
| |
| 21 If we would distinguish in a qualitative way and i
| |
| 22 say a filtered vent release is evidently the noble gas 23 activity and a la rge release ought to be anything notably in r~' 24 , excess of that -- and there is a curve I am going to show i
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| 25 1 you in a moment -- that noble gas activity alone is a ACE-FEDERAL REPORTERS, INC.
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| 2t:2447- 170) Nanonu ide Emerage
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| * X L DMM6
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| 071 10 04 122 1 DAVbur 1 nontrivial release.
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| 2 Therefore, for purposes here we are talking about 3 a relatively unmitigated release that involves relatively 4 large quantities of aerosols.
| |
| 5 Yes, sir.
| |
| 6 DR. SHEWMON: If I put zero up there as a 7 probability, you would doubt my veracity. Anybody who puts 8 1.0 up there, I kind of doubt, too.
| |
| 9 MR. BERNERO: I was about to get to that one.
| |
| 10 That is actual.
| |
| 11 There are two plants in here that are a problem.
| |
| - 12 This is Limerick. This is GESSAR II. It really was 13 evaluated in both cases, but the meaning is incorrect if you 14 say 1.0.
| |
| 15 The 1.0 in that particular entry actually 16 represents containment failure by just relieving pressure, 17 just as WASH-1400 actually had -- if you went through here, 18 that same 1.0 could have been put in -- WASH-1400 had 19 pressure relief in all accident sequences but not all of 20 them were unmitigated releases.
| |
| 21 WASH-1400, if you entered an inferred number --
| |
| 22 and the text of the letter does that --
| |
| it is that infamous 23 90 percent failure probability that Harold Denton used.
| |
| ,~, 24 In this particular case, if you go into the 25 ' hearing record for Limerick, that number is on the order of ACE-FEDERAL REPORTERS, INC.
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| l ae.w.~ ~ _ + c- -
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| 071 10 05 123 1 DAVbur 1 50 percent. The containment always bursts in the analysis, 2 but roughly half the time the burst was a filtered release 3 and half the time it was not.
| |
| 4 So the proper entry here for -- whether I will 5 call it the fraction resulting in large release or this 6 improperly identified conditional probability, the proper 7 entry here is 50 percent or less than 50 percent.
| |
| 8 The proper entry here is 90 percent, and the 9 proper entry for GESSAR II -- you may recall that safety 10 evaluation report. The containment bursts in the wet well 11 all the time, and the unfiltered outcome was a tiny 12 fraction. In fact, it would be dominated by what is the 13 likelihood of pool bypass. It is a very small number, on 14 the order of, say, 1 percent.
| |
| 15 Therefore, if in a systematic, this column needs 16 some correction to put it all on the basis of the fraction 17 resulting in large release. In that case it ranges from 90 18 percent down to 1 percent, say, on a Mark III containment 19 because the Mark III has a dry well that is vastly more 20 strong than the wet well.
| |
| 21 DR. MARK: Which is the 90 percent?
| |
| 22 MR. BERNERO: 90 percent would be WASH-1400, the 23 reactor safety study, because in the BWR the dominant
| |
| '^) 24 , releases were not filtered releases.
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| l 25 DR. SHEWMON: And at Limerick that I asked about, ACE-FEDERAL REPORTERS, INC.
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| 202 347-37(u) Nanonwide l os erage Mak3% uwm
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| r--
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| 071 10 06 124 1 DAVbur 1 that is translated .5?
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| 2 MR. BERNERO: It is 50/50 or slightly less than 3 50/50, yes, sir.
| |
| 4 DR. OKRENT: It is my recollection that for 5 GESS AR there remained an open question concerning the 6 possibility of failure of the pedestal, and therefore a loss 7 of integrity of the dry well and hence --
| |
| 8 MR. BERNERO: A bypass.
| |
| 9 DR. OKRENT: A partial bypass because some of the 10 fission products might have gotten into the pool, but a 11 nontrivial fraction would be available to get through 12 another path.
| |
| 13 I have not seen anything put out by the staff 14 that says that this failure mode can now be neglected.
| |
| 15 MR. BERNERO: One of the difficulties we have not 16 evaluated --
| |
| in fact, you could say that for almost every 17 one of those -- the fraction resulting in a large release is 18 not an explicit product of any PRA. One just doesn't 19 calculate it, and in GESSAR II it wasn't calculated.
| |
| 20 The matter was left, but the fraction which would 21 , have resulted in a large release was that whatever the I
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| 22 population of those sequences that result in a dry well pool 23 bypass -- pedestal collapse, the vacuum breaker, or ej 24 ventilation pan path collapse -- whatever event would result 25 ! in bypassing the pool and the filtration mechanism, and it ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coserage RXb DMMA
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| 071 10 07 125 1 DAVbur 1 was never calculated.
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| 2 DR. OKRENT: But you gave 1 percent?
| |
| 3 MR. BERNERO: Yes, that is my interpretation, and 4 you have apparently suggested that the uncertainty is 5 greater than that and it might be -- I don't know. You 6 didn't name a number -- 10 percent?
| |
| 7 DR. OKRENT: You have 1 percent, if I understood 8 it correctly, as your central estimate. I am not aware of 9 its basis.
| |
| 10 MR. BERNERO: It was not explicitly evaluated. I 11 would infer it from the text, just as one infers 90 percent 12 from the reactor safety study.
| |
| 13 DR. OKRENT: Well, what I am getting at is that 14 if most core melts were to lead to failure of the pedestal 15 and most of those led to failure of the dry well --
| |
| 16 MR. BERNERO: Then it would be a high fraction, I
| |
| 17 indeed.
| |
| 18 DR. OKRENT: At least it seems to me it would be 19 unlikely to be 1 percent.
| |
| 20 MR. BERNERO: And if most core melts led to a 21 l Very energetic direct heating and consequent failure of dry 22 well and containment, then it would indeed be a high 23 number.
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| ' ', 24 You know, really what you are saying is there is 25 an uncertainty, and one can choose to deal with that as a ACE-FEDERAL REPORTERS, INC.
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| 202-347-3701 Nationwide Coserage N n 33MM6 l
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| 071 10 08 126 1 DAVbur 1 dominant uncertainty or as a low uncertainty.
| |
| 2 When I give something on the order of 1 percent, 3 I am saying my interpretation of that record is it is not a 4 dominant uncertainty.
| |
| 5 (Slide.)
| |
| 6 The key results I would just summarize for BWR 7 containment.
| |
| 8 Again, it is in the context of this fraction 9 resulting in an early release for the distribution of 10 accident sequences that that particular plant has.
| |
| 11 The reactor safety study, Peach Bottom, 90 12 percent is the approximate value of the early or large 13 release for the family of core melts.
| |
| 14 IDCOR studied the same plant, the Peach Bottom 15 plant. Again, it was not explicit, but upon request earlier 16 this year Philadelphia Electric actually looked at the 17 results and said what is the approximate fraction, and they 18 came up with a number on the order of 20 percent.
| |
| 19 Vermont Yankee, in a 60-day containment study, 20 tried to infer -- first of all, from Peach Bottom accident 21 distributions they translated it to Vermont Yankee by 22 changes or differences in plant design, and they got a 23 family of accident sequences that was at least tentatively appropriate to Vermont Yankee. Then they did containment
| |
| {^ 24 l 25 event trees, and they came up with 7 percent.
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| ACE-FEDERAL REPORTERS, INC.
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| 202 347 37m Nanonwide Coserage
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| )
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| 071 10 09 127 1 DAVbur 1 Now, they are slightly smaller. I distributed to 2 the committee a table of data for all the BWRs, and in that 3 table of data -- you can look -- the containments don't vary j 4 that much, the Mark I's, in size, although the reactors l 5 inside the containments vary over a factor of 2 in size.
| |
| 6 Vermont Yankee is one of those half-sized 7 reactors in a 90 percent sized Mark I containment. So this 8 is a surprisingly close outcome in round numbers, 10 9 percent.
| |
| 10 Now, NUREG-ll50 is not available to us yet, but 11 we have had plenty of warning that the uncertainties are 12 such that will come back to something like the reactor 13 safety study, at one end of it at least.
| |
| 14 So we expect the outcome of NUREG-1150 to be 15 somewhere in the range described by these three earlier 16 things, and why is that so? What are the features of that 17 containment?
| |
| 18 (Slide.)
| |
| 19 Here is an elevation view. It is slightly 20 different from the view you have in your packet, but it is a 21 i simple line diagram.
| |
| 22 DR. MOELLER: Excuse me. To say it will be in I
| |
| 23 the range is to say that it will be between 7 and 90
| |
| (~'; 24 percent? {
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| 1 25 MR. BERNERO: Yes, 10 percent to 90 percent. l l
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| ACE-FEDERAL REPORTERS, INC.
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| wnm s,w a c~,. wwn
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| 071 10 10 128 1 DAVbur 1 What they publish now for Surry -- well, they 2 haven't published it, but at least we have been reviewing i
| |
| 3 it and it has been briefed to the Commission -- that the 4 early release fraction is somewhere between 1 percent and 60 5 percent.
| |
| 6 So 10 percent to 90 percent for the Mark I would 7 not be surprising at all.
| |
| 8 But if we look at this containment -- I will 9 boost the picture up a little bit -- why should this 10 containment be so vulnerable?
| |
| 11 If you look at it, the first thing you see is it 12 is very small. For the reactor within it, it is a very 13 small, three volume.
| |
| 14 What is means is that if you have a large scale 15 core melt -- remember the sequence of events. When you 16 roast the core, the early phases of a core melt, you drive 17 off the gaseous and volatile activity as the fuel 18 disintegrates, and the relief valves conduct these volatile 19 materials -- the gases, the cesium, the iodine, and the 20 cesium iodide if that be it. If they are conducted down 21 into the suppression pool, where the relief valve tailpipes 22 go, they go right down into the water.
| |
| 23 Now, obviously, the noble gases are not
| |
| (^' 24 f scrubbed. They are obviously not sufficiently soluble.
| |
| ' J l 25 They will just cycle around. But the cesium, the cesium ACE-FEDERAL REPORTERS, INC.
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| 202147 3'm Naronnie ( oserage m L31MM6
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| 071 10 11 129 1 DAVbur 1 iodide, they will be captured in the pool.
| |
| 2 But if there is large scale pool melt, it has to 3 dissolve through the control rod assemblies, which are in 4 the bottom of the BWR, and then work its way down onto the 5 floor, the lower head area.
| |
| 6 Now, this area is open to the surrounding 7 containment, but notice you have a very narrow island of 8 space, not an island -- it is an annulus or disc of space.
| |
| 9 The dry well wall is very close to the lower head area. The 10 downcomer vents to take the steam away are close by.
| |
| 11 And the result is if you have a large scale core c- 12 melt, the debris, being so hot, has the ability to directly J
| |
| 13 attack corrosive attack of the wall. It has the ability to 14 have radiant heat transferred to the wall very intensely an 15 a convective heat transfer. And of course, while it is in 16 contact with the concrete, you can have vigorous 17 core-concrete interaction, and that core-concrete 18 interaction can generate a lot more hydrogen, CO-2, and 19 entrain aerosols while it is at it.
| |
| 20 Yes, sir.
| |
| 21 ! DR. SHEWMON: As I recall, GE takes a different I
| |
| i 22 : view of the vulnerability of this.
| |
| 1 23 i Is the difference of opinion between them and the
| |
| '~N 24 staff whether the operator will be able to get water into 25 this or what?
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| ACE-FEDERAL REPORTERS, INC.
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| 3-., ~ _ < - ,. _
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| I 071 10 12 130 1 DAVbur 1 MR. BERNERO: Remember, we are speaking in 2 conditional probability space. I think everyone would 3 agree -- and the results on that big, complex table do tend 4 to support it -- that all else being equal, you are most 5 likely better able to keep from melting the core in a BWR 6 than in a PWR.
| |
| 7 They have got more water systems and more 8 adaptability, and if you can't work at high pressure you 9 relieve it down to low pressure, and it is pretty well 10 established that it is a more flexible system.
| |
| 11 It starts out being two-phased, and you don't 12 mystify the operator with double bubbles and the things like 13 that that you have in a PWR. So its likelihood of core 14 melt is probably somewhat lower.
| |
| 15 Nonetheless, if you do have a large scale core 16 melt and accept the possibility of melting through all of 17 the hardware in the lower end, which is going to tend to 18 make a more dilute corium -- it has more inert metal in 19 it -- we are speaking solely of the conditional 20 probability. The situation, never mind how it happened, you 21 ; are there.
| |
| 22 l You have got large scale core melt on the floor, l
| |
| 23 ! and that is the vulnerability we are speaking of.
| |
| I
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| ~N 24 MR. WYLIE: But your sprays are pouring water on i
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| that all the tine?
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| 25 l l
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| i ACE-FEDERAL REPORTERS, INC.
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| :ew m ~ _& c-- nu-
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| y___ -
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| a\
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| -q 071 10 13 131
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| -l
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| .A 1 DAVbur 1 MR. BERNERO: Not yet. i h
| |
| 2 The situation in the plant is that you have this ~~ l-t 3 chance of generating a lot more hydrogen besides the 4 hydrogen you have generated in the core degradation up 5 inside. You have got a chance to have all these extra 6 aerosols, inert materials of all kinds, and there are some 7 things already in place that help to mitigate.
| |
| 8 One, we have already inerted these conta,inments. 'l f
| |
| 9 So we have taken the edge of f the hydrogen threst, the -
| |
| 10 hydrogen combustion threat. By inerting, the hydrogen now 11 becomes an inert gas, just another inert gas.
| |
| 12 We also have in these containment 3 -- right about i
| |
| 13 this level here in the typical plant, one on top of the 14 other, are two spray ring headers. They are fed -- on the 15 typical plant, it is an alternate mode of operationTof the 16 RHR system -- RHR is valves -- such that you c.in squirt into 17 the reactor or into these spray headers and get a rather 18 high flow, fully developed spray pattern all through this 19 space here.
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| 20 21 22 23 k 24
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| 25
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| . ACE-FEDERAL REPORTERS, INC.
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| 202 .14 t .P(O Nationwitle t owrage xoik lWI646
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| ll '
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| v
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| 071 11 01 132 1 DAVbw 1 So that is goodness, but although a safety grade 2 system, a redundant system, you know, two independent 3 trains, and all that, it's an alternate mode with little 4 priority, because the priority is, of course, cool the 5 core. And this containment has this fragility, due to being 6 very small and having molten core material right here.
| |
| 7 In addition, even if you are cooling it, here it
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| \
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| 8 depends on the model. How much inert gas are you dealing 5
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| 9 with, how much hydrogen is generated at each state of the 10 reaction? How much CO2 is generated by core-concrete
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| . w 11 interaction. Depending on the amount of inert gas generated 12 and the inert average pressure an.d temperature which will
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| ,' 13 drive the pressure, you can reach overpressure of the 14 containment rather easily.
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| i r 15 The design pressure of the typical Mark I 16 containment is on the order of 50 to 60 psi, but the volume 17 is a factor of 8 or 9 less than a large dry containment. So 18 the inert gas can build up to burst pressure rather soon.
| |
| 19 If you build up to burst pressure, analysts have w"4.stled 20 with this for sometime, at what point would it burst?
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| 21 ; Conventional wisdom up to now has said, it is going to break t
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| '[ 22 at the knuckle right about here. Somewhere around twice 23 ! design pressure. People looking more at that say no, the
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| 'N 24 l biological field is going to back it up. It is probably s 25 going to break down here somewhere at a somewhat higher ACE-FEDERAL REPORTERS, INC.
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| 202 347-17m Nanonwide Umcrage
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| * n))MM6
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| 071 11 02 133 1 DAVbw 1 pressure perhaps as high as three times design pressure, 2 but it still is very likely to reach a bursting pressure, 3 unless you do something about it.
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| 4 DR. REMICK: There was something I missed.
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| 5 You answered Charlie on his question on why you 6 wouldn't have water from the containment spray, but you must 7 be assuming here that because you had a core melt that 8 there's no chance of HPCI, LPCI, RCIC or core spray putting 9 water into the core spray down into the cavity.
| |
| 1 10 MR. BEPNERO: That may be why you have a core 11 melt. If you had an RHR LPCI system, you wouldn't have a 12 core melt. So it is an academic question. It is the very 13 reason why I question it, and remember, someone remarked 14 that the spray is not out here, it is not down here.
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| 15 There is one or two doorways in those things, 16 usually, but keeping that in mind, let's look at a summary.
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| 17 Now vulnerabilities, some of which are either fixed or 18 partially fixed --
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| 19 (Slide.)
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| 20 -- you've got a small volume, exposing rapid 21 cverpressure vulnerability and especially vulnerable to 22 hydrogen burn, but as I said, they are already inerted, 23 although you have a window, the tech spec window of 24 hours 24 at the beginning and at the end of the cycle, where you 25 don't have to be inerted, it is a small drywell floor. The ACE-FEDERAL REPORTERS, INC.
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| mem.m ~ _ . < - mu_
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| 071 11 03 134 1 DAVbw 1 lower head area is close to the drywell wall. There is that 2 potential for direct debris attack, and of course, direct 3 heating by radiation or convection.
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| 4 A characteristic of the containment is passively, 5 the way Wasil-1400 evaluated it. Look at the thing and 6 watch. It has relatively little capability to cope with the 7 core melt, but actively, because, again over the many 8 diverse systems and alternatives, there are options for 9 active response that open up avenues of improvement.
| |
| 10 What we say in the generic letter is, there is a 11 five-element approach to the improvement of this containment 12 that embraces control of hydrogen, whether reaffirming what 13 we have or changing control of the sprays in the drywell.
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| 14 An extremely important function, the pressure relief, in 15 order to avoid catastrophic failure, control of core debris, 16 and lastly, the procedures and training for this active 17 response.
| |
| 18 Now one thing I want to put up, because it is 19 significant --
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| 20 (Slide.)
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| 21 Earlier on I said that the success state is a 22 filtered release of the noble gas. I invite your attention 23 to the is figure in the letter.
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| 24 This is all noble gas released. This assumes all 25 of it coming out after a one-hour hold up in decay before ACE-FEDERAL REPORTERS, INC.
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| mmm x _ m <- m_ l
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| 071 11 04 135 1 DAVbw 1 release.
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| 2 Remember, the noble gases have three half lives.
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| 3 If you speak of noble gas activity in a power reactor, there 4 are three half live regimes of interest, and the easier way 5 is to start at the tail end of the curve and work back 6 uphill. Everyone knows krypton-85 has a ten-year half life, l
| |
| 7 and we had a building full of it at TMI for a year and had f 8 ample discussion of it. It is a very small dose, a very, 9 very small dose.
| |
| 10 When you back up on the curve, there is a point 11 within a month or two of shutdown, where the half life is 12 not krypton-85, but xenon-133, 5.2 days. That is the 13 dominant activity that was in the TMI building for the days, 14 for the weeks after the accident, why people couldn't go in 15 there, you know, and freely walk around. It is a 5.2 day 16 half life.
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| 17 Then when you get up to within hours of shutdown, 18 you go into a steeper half life curve, which is a whole 19 family of short-lived activities. Basically, you have a 20 fairly significant decay from 23ro to one hour, and you are 21 making the transition f rom one hour to maybe eight or twelve 22 hours, before you really get to the xenon-133 period or half 23 life regime.
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| 24 We chose, since it takes about an hour to melt 25 the core, if you want to do a fast core melt, it takes about ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nanonaide Coserage W 3 36-6M6
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| 071 11 05 136 1 DAVbw I an hour. We chose one hour as the lag time, and we took two 2 elevations of release, a 10-meter release and a 100-meter 3 release.
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| 4 What is the off-site dose to a member of the 5 public or a member of the plant staff for that matter, if 6 you had such a release?
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| 7 The solid line here is for elevated release at 8 100 meters with expected meteorology. This is 50 percentile 9 meteorology. If you flip to rare or bad meteorology, here 10 is the curve, this is the 95 percentile, or if you invert 11 it, the 5 percentile meteorology.
| |
| 12 Notice the dose. 20-rem whole body, pretty much 13 for the first two miles, and over here, the 96 percentile is 14 on the order of 100-rem whole body. You can up into the 15 clinically detectable effects, the radiation injury range.
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| 16 on the other hand, if you make it a ground level 17 release, a nominal 10-meter, as if it blew out a side panel {
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| 18 in the building, then the ground level release in the first 19 two levels -- here is the expected meteorology, and here is 20 the 95th percentile, you can get up into lethal doses.
| |
| 21 So keeping that mind, the noble gas release 22 should be one, something you don't routinely adopt as an 23 alternative, and it should be released at a high point. With
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| ,' )
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| 24 that frame of reference of off-site dose, it should lead one 25 to say, you don't want to have that stuff bursting inside ACE-FEDERAL REPORTERS, INC.
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| 2112-347-3700 Nationwide Coserage 80IL33 M 646
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| 071 11 06 137 1 DAVbw 1 the reactor building. You don't want the operators immersed 2 in it.
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| 3 DR. KERR: Let me make sure I understand. That 4 is based on the assumption or the release occurs one hour 5 after shutdown?
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| 6 MR. BERNERO: Yes. In other words, the noble gas 7 has decayed one hour after shutdown, and the person out 8 there now sees the whole puff.
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| 9 DR. KERR: Do you wait 12 hours and it goes down 10 by, you say, perhaps a factor of 30?
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| 11 MR. BERNERO: No. In fact, I was asking a member 12 of Staff today, we've got a whole bunch of calculations.
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| '~~
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| 13 DR. KERR: I am just looking at number one up 14 there.
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| 15 MR. BERNERO: It can be as much, but what I'd 16 like to do is have a sensitivity that goes one hour or two 17 hours, five hours. You know, something like that, to give a 18 little bit better bracket than that. You know, there is l
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| 19 something appreciable, and it is going to vary by sequence, 20 but we backed up to the one hour, as the more conservative 21 one.
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| 22 DR. MOELLER: These are noble gases only?
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| 23 MR. BERNERO: Just noble gases.
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| 24 So this assumes a scrubbed release. The French, s.
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| 25 as you know, have that sand filter with a DF of 7 to 10 or ACE-FEDERAL REPORTERS, INC.
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| 2tl2-347 37m Nationode Coserage 83 L33M446
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| ~
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| 071 11 07 138 1 DAVbw 1 something like that.
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| 2 So in their calculation, they would get the noble 3 gas. You know, they might be out at 12 hours and get 30 4 times less than that, plus whatever residual particulate 5 would be in it, depending on the efficacy of the filter.
| |
| 6 So I am missing a slide here.
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| 7 I wanted to summarize -- excuse me for minute. I 8 took one slide out that I shouldn't have taken out.
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| 9 You should have it. It is containment 10 improvement strategy. I skipped it. I mistakenly took it 11 out of the pile.
| |
| 12 (Slide.)
| |
| 13 The containment improvement strategy goes like 14 this:
| |
| 15 First of all -- there are far more words, of 16 course, in the letter.
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| 17 The first thing is, let's look at hydrogen. We 18 obviously want to prevent that combustion. We have inerting 19 now, and the issue evolves into, do we have to do something 20 besides inerting? Do we have to eliminate that tech spec.
| |
| 21 Do we adjust that tech spec from 24 hours to 12 hours?
| |
| 22 Well, in one sample case -- this is Vermont Yankee -- there 23 was a study made of the logbooks for three years in a 24 typical BWR Mark I, and I would assert that that is m-25 typical. How long did they operate on inerted? It works ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Cos erage Mn336-%26
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| 071 11 08 139 1 DAVbw 1 out to be 1.1 percent of the time.
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| 2 The Owners Group is doing a survey of other 3 plants, but it appears that we are working on a very small 4 fraciton of one contributor to risk, and therefore, at this 5 time, the letter says, it isn't worth altering that tech 6 spec. It merely reaffirms present requirements, and so what 7 it says is, by inerting, the hydrogen control remains the 8 same.
| |
| 9 Now the drywell spray was designed to fit the 10 pumps available to feed it. The pumps in question are the 11 RHR LPCI pumps, which, in a boiling water reactor, are about 12 the largest things they have in the reactor side of the 13 house.
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| 14 They are very high flow pumps, and depending on 15 how they size the manifold and spray nozzles, they typically 16 provide so much water, that there operating procedures are 17 filled with precautions. Don't overdo it. Don't overspray 18 and collapse the darn thing.
| |
| 19 If you have a system designed for feed by a very, 20 very large pump, and that pump doesn't work and going back 21 to an early thought, maybe that is why you have the core 22 melt, what available pumps might be connected as backup 23 supplies?
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| ^
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| 24 The difficulty is, that the system is designed
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| )
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| 25 only for a 10,000 gpm pump. Where are yo going to find a ACE-FEDERAL REPORTERS, INC.
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| 202-347 3700 N ationwide Coserage # 4 33 M 646
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| ~ -
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| E ]
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| I 071 11 09 140 1 DAVbw 1 10,000 gpm backup?
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| 2 So the first requirement here is cut the number 3 of nozzles, roughly, in order of magnitude, in order to 4 enable smaller pumps that are available in the plants, 5 smaller systems, to produce and feed water, such that they 6 will produce the spray in the containment, not dribble water 7 in, which they would do in a system designed as it is now, 8 but produce a developed spray pattern, and that you would 9 have backups, and it does two things for you. It gives you 10 different ways to get the spray pattern, and it also 11 maintains your control geometry.
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| 12 You don't have some very large flow rate trying
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| ~
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| )
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| 13 to flood up the torus and shifting into a flooded geometry.
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| 14 It extends your water supplies and still leaves you with 15 controlled geometry.
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| 16 Keep in mind, even a 1/10 flow rate, a 1/10 RHR 17 flow rate, can flood the drywell in something on the order 18 of 15 minutes.
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| 19 (slide.)
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| 20 The drywell, remember, is only about a foot deep 21 right there. You can put about a foot of water there, and 22 ,
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| anything over that will just flow down the vent into the 23 torus.
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| 24 DR. MOELLER: How does this affect any cleaning?
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| 25 MR. BERNERO: Now, wait, if you do that, and ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(10 Nationwide Cos erage 8433MM6
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| 071 11 10 141 1 DAVbw 1 you flow down, you ask yourself what did I lose? Am I 2 getting something for nothing here? It turns out that there 3 was no design basis for that flow, other than the fact that 4 those big pumps were there. So if you have a spray pattern, 5 you can still get scrubbing. If you look at the decay heat 6 mode, you still have plenty of capacity there.
| |
| 7 It turns out, and this is something you have to 8 look at in each plant, about what the right flow rate is.
| |
| 9 It turns out that you apparently do get something for 10 nothing. There was a surfeit of water in the first place.
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| 11 So with that comes a reliability requirement.
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| 12 Now that you have that lower flow, you have to 13 have two backup supplies, and the two backup supplies 14 described are one, maybe alternating current power, 15 conventional AC buses, and the other shall be good in a 16 station blackout.
| |
| 17 The typical plant has a diesel-driven or separate 18 engine-driven fire main system in plant after plant. I have 19 walked through the plants, and you can stand there with one 20 hand on the spray header leading to the reactor building, 21 stand there and look at a fire main 20 feet away or 15 feet 22 away. ;
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| 23 So the typical plant responds not with a wholly 24 new system, but with existing connections or slight 25 adaptations. In order to connect something like RHR ACE-FEDERAL REPORTERS, INC.
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| .3 , x_ c_, - I
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| 071 11 11 142 1 DAVbw 1 service water, conventional service water, fire main water, 2 systems of that sort, to the spray and provide a reliable 3 backup supply for drywell spray, and of course, you get the 4 benefits. You start out with the pool of water on the 5 floor. You have a steady spray coming down to cool the --
| |
| 6 and prevent direct heat transfers and the spread of 7 aerosols.
| |
| 8 DR. OKRENT: Do we know, unequivocally, that 9 adding water into the drywell cannot lead to really adverse 10 interactions between water and core debris?
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| 11 MR. BERNERO: I am not sure I am willing to say 12 unequivocally.
| |
| 13 Let me say this. The primary issue would be one 14 of steam explosion, a vigorous or violent reaction between 15 molten core material dropping into a pool of water and 16 several factors indicate to me that this is not a significnt 17 uncertainty in the boiling water reactor.
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| 18 One, what I would call the consensus or the 19 collective wisdom, the Steam Explosion Review Group results, 20 indicate for the pressurized water reactor geometry, the 21 steam explosion is not a dominant uncertainty. There is 22 ' still debate about it, admittedly, but keep in mind, the 23 pressurized water reactor is, at least in simple form, a e 24 l 12-foot, on a side cube sitting over a bowl full of water.
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| 25 That is a geometry of a PWR.
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| ACE-FEDERAL REPORTERS, INC.
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| l 202 347 370n saiionwiae cos erage sonx336-,u6
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| 071 11 12 143 1 DAVbw 1 The geometry of the BWR, the bowl is full or 2 hardware.
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| 3 And given that in the BWR, the large-scale core 4 melt was designed for that hardware in order to have c bulk 5 of corium reach the lower head area, the corium is, first of 6 all, more dilute. It is necessarily more dilute, and as 7 such, I think-it is as a somewhat lower temperature.
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| 8 Secondly, it is falling into a very limited pool 9 of water.
| |
| 10 The geometry here limits you to about one foot.
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| 11 Some plants are as little as seven inches, some perhaps as 12 much as 15 or 16 inches, but that is it.
| |
| 13 So to get a large amount of corium to disperse 14 ef fectively and immediately in a large amount of water and 15 thus generate the steam explosion, I am not sure I can say, 16 unequivocally, but I think the proponderance of evidence is 17 that it is not detrimental, that it is favorable for cooling 18 and crunching corium material, as it comes out and as it 19 tries to progress across the floor.
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| 20 21 22 4 23
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| ~'
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| 24
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| -)
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| 25 ACE-FEDERAL REPORTERS, INC.
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| L C-347-37 W Narionw kle Coserage Mn336-6M6
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| 1 071 12 01 144 1 DAV/bc 1 DR. OKRENT: Again, you may be correct but let me 2 just ask is there any mode of a significantly adverse steam 3 explosion outside of the support structure into which the 4 molten fuel first falls?
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| 5 In other words --
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| 6 MR. BERNERO: If you reduce that flow rate, it's 7 virtually impossible to get more than a foot of water.
| |
| 8 You'd have to flood the whole containment.
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| 9 DR. OKRENT: I don't have a feel at the moment 10 for whether a foot of water interacting with some plausible 11 amount of molten or quasi-molten material can do damaging 12 effects to the dry well.
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| ~
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| 13 Maybe somebody has done a bounding calculation 14 and shown that it doesn't matter if a steam explosion 15 occurs. It's my impression that steam explosions of modest 16 size can occur with a fairly high degree of likelihood of 17 you have water and the molten material around.
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| 18 MR. BERNERO: No doubt.
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| 19 DR. OKRENT: So it becomes a question of not 20 being able to get something sufficiently damaging, which is 21 why I phrased the question with those qualifying words.
| |
| I 22 ! MR. BERNERO: It is certainly. Anytime you would 23 take material at approximately 5,000 degrees Fahrenheit and 24 drop it in blobs or globules into water that's at 100 25 degrees Fahrenheit, it's going to De rather exciting.
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| ACE-FEDERAL REPORTERS, INC.
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| I sc. - x _ m c- --
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| 071 12 02 145 2 DAV/bc 1 You're going to get very vigorous exchanges and 2 bubbling and spattering and bursting. And I cannot say that 3 that is clearly harmless to the containment.
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| 4 The only thing I can say is it falls, once again, 5 going back to the picture.
| |
| 6 (Slide.)
| |
| 7 The initial dropping is into a relatively 8 enshrouded area that doesn't have spray on it, but merely 9 has whatever water can flow into it. If there is vigorous 10 spattering or knocking around, not vigorous in terms of a 11 steam explosion in a reactor ves'sel that would tear the top 12 off, but knocking things around, it is already mechanically 13 shielded somewhat.
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| 14 And then, if it comes out, depending on where the 15 doorways are, they vary from plant to plant, the 16 recirculation loop is out there, that's what that pump is, 17 you have some hardware. In fact, it's a very crowded area 18 for recirc loops and piping, and things like that, before 19 you hit the wall.
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| 20 One can only use engineering judgment. I know of 21 no calculation. And we certainly didn't attempt any that 22 would say:
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| 23 This is the kinetic energy of a maximuni credible 24 particle that could hit the wall of the dry well. We just V,
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| 25 didn't do it.
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| ACE-FEDERAL REPORTERS, lNC.
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| - ~ _ m- - I
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| I 071 12 03 146 1 DAV/bc 1 DR. OKRENT: It just seems to me it would be 2 useful if one could be assured that, in all of the Mach I's, 3 there was no surprise waiting for one, some kind of a steam 4 explosion that in fact leads to a rupture of the dry well.
| |
| 5 It doesn't strike me as something that one 6 couldn't do, at least initially, some order of magnitude 7 estimates to see if the potential is even there.
| |
| 8 If the notential is there, one would then perhaps 9 have to look more closely to see if it can be.
| |
| 10 MR. BERNERO: I really think we're touching on a 11 difficulty that has haunted Mach I analyses for years. If 12 you go into the very elegant, long-range, massive program 13 analyses, the source term analyses, for years, people have 14 said the failure is right there at the knuckle.
| |
| 15 And then of course it's analyzed as if it 16 relieves into the reactor building. Mechanistically, it is 17 so hard to model the hardware that's in the way, the fact 18 that the dry well shell is that far away from a massive 19 reinforced concrete biological shield. There is no free 20 path to the ambient.
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| 21 Two of the Mach I's are reinforced concrete 22 vessels with a steel liner. The rest of them are 23 freestanding steel vessels with this big biological shield r~' 24 around it.
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| L) 25 In any case, if you were to have a truly ACE-FEDERAL REPORTERS, INC.
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| I mme m s _ m- m_
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| 071 12 04 147 1 DAV/bc 1 bypassing f ailu: e due to debris ejection by steam explosion 2 in the lower cavity, it not only has to miss the hardware, 3 it has to go through.
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| 4 Merely perforating this is not a significant 5 failure, although I must admit it's the fallback position.
| |
| 6 It gives you noble gases in the reactor building, which is 7 not desirable but you still get an awful lot of filtration 8 and attenuation.
| |
| 9 It's not a free path to the outside.
| |
| 10 MR. ETHERINGTON: When you speak of a steam 11 explosion, you're talking about shock or static presr2re?
| |
| 12 MR. BERNERO: In this particular instance, I 13 would be talking more about the debris than I would about 14 the pressure effects, because the pressure effects -- a 15 pressure suppression containment is much more resilient 16 unless you get a very, very rapid pressure pulse that can't 17 be dissipated.
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| 18 After all, this thing was designed to absorb a 19 guillotine rupture of a very large pipe and to respond 20 quickly to that. I would be more concerned about the debris 21 ejection than the other.
| |
| 22 DR. REMICK: Bob, a question. On the pumps that 23 ' you're talking about, the small pumps, do you envision those 24 being in the RHR quandrants, or would these be out in the 7 ,
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| 25 engineering building outside the dry well?
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 NJtionwide Cm erage sn3w6so
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| 071 12 05 148 1 DAV/bc 1 MR. BERNERO: They are where they are. They're 2 existing pumps. I personally walked down. I think I've 3 walked down 21 Mach I's. But you go and you look. In 4 Vermont Yankee, they have a 1,200-gallon a minute diesel-5 driven fire pump that sits in a separate pumphouse. It's 6 like a blockhouse. It's on the shore of the Connecticut 7 River, which is their heat sink.
| |
| 8 It's diesel-driven and it's already piped into 9 the spray header. It's just a matter of opening the 10 valves. There are no new pumps identified here. It's using 11 existing systems and really changing valves or changing 12 spool pieces and flanges.
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| 13 DR. REMICK: In some cases, an interconnection.
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| 14 MR. BERNERO: Oddly enough, Vermont Yankee must 15 have 10 pumps connected, alternate sources. Why nobody 16 seems to know. They just belt with suspenders when they 17 designed the plant. It's a matter of selecting what they 18 would use rather than building or installing.
| |
| 19 DR. KERR: Would you talk about a source that 20 , should supply water given a station blackout? Does station 21 li blackout include the demise of this diesel-driven fire I
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| i 22 pump.
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| 23 MR. BERNERO: No. We have a problem in this 24 agency when we talk about station blackouts because from
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| ()
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| 25 plant to plant, its meaning differs. The classical PWR, ACE-FEDERAL REPORTERS, INC.
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| 202-347-3?00 Nationside Cos erage NU-33MM6
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| 071 12 06 149 1 DAV/bc 1 which is the classical model people have in mind when they 2 speak of it, has division one, division two diesel 3 generators and off site power.
| |
| 4 Given less of off site power, diesel 1 DG fails, 5 diesel 2 DG fails, we have station blackout. All I have is 6 one turbine-driven aux feed pump. That's the mental image 7 of station blackout that all of us have when you say A44.
| |
| 8 But, now you look at a boiling water reactor.
| |
| 9 You've got in the old ones division one, division two and 10 two turbine-driven systems, RCIC and HPSI.
| |
| 11 In the later model BWR's, you have division one, 12 division two and division three, a third diverse diesel 13 generator plus a RCIC.
| |
| 14 DR. KERR: That's the reason I asked.
| |
| 15 MR. BERNERO: So, station blackout, I think, 16 really has to mean the loss of vital buses A and 7 and off 17 site power. I mean, loss of vital buses A and B due to loss 18 of off site power.
| |
| 19 DR. KERR: A dedicated diesel.
| |
| 20 MR. BERNERO: Dedicated diesels.
| |
| 21 DR. KERR: It would do all that with station 22 blackout.
| |
| 23 MR. BERNERO: When you get to Shoreham, they must 1 24 have about 12 diesels up there now, plus a gas turbine.
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| 25 It's very difficult to define a blackout for that site.
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(M) NationMdc CO\Crage s(x> 3356u6
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| 071 12 07 150 1 DAV/bc 1 So what I am referring to is really a source of 2 motive power that's independent of the normal safety buses, 3 vital buses A and B.
| |
| 4 MR. EBERSOLE: Bob, I think you have to add 5 though: And independent of environmental conditions or 6 requirements depending on electrical power of which HPSI and 7 RCIC are not one.
| |
| 8 MR. BERNERO: They have a limited time, that's 9 right.
| |
| 10 MR. EBERSOLE: By the way, I take it you're 11 isolating this notion from the notion that earthquake events 12 led to your problem?
| |
| '~
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| 13 MR. BERNERO: That's covered elsewhere.
| |
| 14 DR. OKRENT: One more question. You've ruled out 15 then that a steam explosion inside the region below the 16 pedestal could damage selectively one region of the pedestal 17 so that the pedestal collapsed.
| |
| 18 MR. BERNERO: The residual uncertainties that are 19 not explicitly recognized but are obvious are that steam 20 explosions causing catastrophic failure or early release 21 either in vessel or ex-vessel, direct heating sufficient to 22 overpower the condensing vetns -- you know, the pressure 23 suppression capability -- is a residual uncertainty deemed 24 not significant.
| |
| v 25 Later on, I'll talk about the seismic one.
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347- 3 ?(X) Nationwide Cos erage $(X L 336-f646 l
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| ~
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| 071 12 08 151 1 DAV/bc 1 They're not included. Perhaps they should be explicitly 2 covered as why they are excluded.
| |
| 3 DR. OKRENT: Your answer was it's your opinion 4 this is a sufficiently low probability, or you just assumed 5 it away, or it hasn't been analyzed?
| |
| 6 MR. BERNERO: Former is the answer.
| |
| 7 MR. EBERSOLE: Bob, before you get to this 8 disastrous temperature condition that melts the core, you've 9 achieved environmental conditions that have long since 10 disabled the low pressure venting system, the SRV solenoids.
| |
| 11 So you have closed up, haven't you? Now, you may 12 have high temperature /high pressure superheated steam.
| |
| 13 Am I correct?
| |
| 14 MR. BERNERO: It depends. One of the factors you 15 consider in selecting a venting pressure venting the 16 containment, there are three factors that you should 17 consider in choosing a pressure at which to vent the 18 containment. I'll talk about that in a moment.
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| 19 One is how much can the containment assuredly 20 l-stand in the way of pressure?
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| 21 At what pressure can you assuredly operate a 22 vent?
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| I 23 i Thirdly, have you considered the back-pressure
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| (~ , 24 f reclosure of the SRV's?
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| \
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| 25 MR. EBERSOLE: I wasn't talking obcu e the ACE-FEDERAL REPORTERS, INC.
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| _ ~ c- -- - 1
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| 71 12.09 152 l~ DAV/bc 1 containment event.
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| 2 MR. BERNERO: You were talking about the SRV's 3 -being forced back shut by high pressure in the dry well.
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| 4 MR. EBERSOLE: I'm talking about the fact that
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| .5 the SRV's are held open by the active energization of the 6 solenoid valves. By the time you've got enough temperature 7 to melt the core,-those valves have died long ago.
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| 8 And I suspect you have a primary vessel pressure, 9 which is right up to the disabled system pressure, super-10 heated steam. And when all this goop comes out of the 11 bottom and you have the control rod drives, it's going to
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| - ,s 12 come out with some force, which is rot a very placid t \
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| 13 injection method.
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| 14 MR. BERNERO: I'm not saying it's placid.
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| 15 MR. EBERSOLE: It's not just called a pour out.
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| 16 It's going to come out with a shot.
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| 17 MR. BERNERO: I'm afraid our engineering 18 intuition differs. I do not believe that you can design 19 tons of metal in such a discrete way as to come out like a 20 shot, even on a PWR.
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| 21 MR. EBERSOLE: It comes out a little at a time.
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| 22 MR. BERNERO: Yes. And the pressure comes down f
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| 23 like gangbusters.
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| 24 MR. EBERSOLE: So it's going to come out in a
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| ['"}
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| x_-
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| 25 high pressure jet.
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| ; ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage 800-336-6646
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| 071 12 10 153 1 DAV/bc 1 MR. BERNERO: I just do not believe that. But 2 let me please...
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| 3 (Slide.)
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| 4 ...the rest of the strategy is that having 5 provided the dry well spray, that there is wet well pressure 6 relief to the stack. If you read the text of the letter, it 7 says that, too, must be operable in a station blackout. A 8 full spectrum of accident sequences.
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| 9 And the argument is, basically, that, first of 10 all, this is a procedure of last resort. You don't want to 11 really release that gas unless you have to. And no one 12 knows for sure what the distribution of accident sequences
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| ~
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| 13 is.
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| 14 At Peach Bottom, we have research with NUREG 1150 15 waxing eloquent about the cumulative core melt frequency is 16 one times 10 to the minus 5 at its all station blackout.
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| 17 IDCOR looks at the same plant with equally 18 competent' people and they say it's 1 times 10 to the minus 19 5, and it's all ATWS.
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| 20 Right there, I've got 2 times 10 to the minus 5.
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| 21 I won't throw either of them out. In fact, I assert that 22 prudence demands that you look at the spectrum of accident 23 sequences and be prepared to deal with the spectrum.
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| 24 Be prepared to deal with loss of injection, loss 25 of containment heat removal blackout, whatever it is. So {
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| I ACE-FEDERAL REPORTERS, INC. l 202-347-3700 Nationwide Coserage 80tk 33MM6
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| 071 12 11 154 1 DAV/bc 1 the pressure relief, this vent, in order to get the pool 2 scrubbing and an elevated release requires a hard vent, hard 0
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| 3 enough to stand the pressure you chose to vent going to the 4 stack.
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| 5 Now, the older plants have that 100 meter stack 6 out in the yard. The newer plants use a stack on the 7 building somewhere. It's not quite 100 meters tall. But 8 get that high release and have the hard duct and select the 9 pressure.
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| 10 And the generic letter says: Select the pressure 11 somewhere between design pressure and 50 percent over-12 pressure. No more. We don't want to count on that margin 13 more than 50 percent. Yes, sir...
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| 14 DR. REMICK: Beyond the pool scrubbing and the 15 torus, you're not going through the standby gas treatment or 16 anything like that?
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| 17 MR. BERNERO: It wouldn't take water vapor 18 anyway. It would just plug on you. There are procedures in 19 many alants where, if it's only a little bit of pressure, 20 you try -- by gas. Or for dry venting, you know. Clean 21 venting.
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| 22 But, now the debris confinement --
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| 23 DR. OKRENT: Excuse me a minute. Before we leave
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| ~
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| /' 24 that bullet, when the French choose to provide a vent, they 25 provide the sand and gravel filter.
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| ACE-FEDERAL REPORTERS, INC.
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| mm x_ r- -
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| 1
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| ~ _
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| 7 071 12 12 155 1 D'AV/bc 1 Why is it not a good measure here if you want to 2 consider a backup to the pool?
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| 3 MR. BERNERO: I'm glad you asked. I was about to 4 flip the drawing back up. And I owe you a dollar for that 5 one.
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| 6 If you look and recall now, there are two things 7 I want to illustrate on the picture. One is are we 8 filtering the exhaust, the vent, properly? And are we 9 controlling debris properly?
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| 10 First of all, remember that the volatile activity 11 comes out first and has forced the bubble through the pool 12 via the relief valve lines. And then, with core on the
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| \
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| 13 floor, lanthanum oxide, or whatever aerosols that are 14 generated by that reaction, are going to come out.
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| 15 And you want to have them bubble through also 16 because you're venting the vapor space here.
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| 17 The question comes up: What about pool bypass?
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| 18 There are vacuum breaker lines. You can have a bypass leak 19 l through a perforation in the liner. If a little bit of 20 debris got there, remember, we had the problem with Oyster 21 Creek, if you had a premature crack, or something like I
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| 22 that. That is one of the reasons why the presence of a 23 continuous spray in the dry well is so important.
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| 24 Now, admittedly, those are young aerosols, right 25 off the core concrete. But you have a cooling scrubbing ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(*) Natioriwide Cos erage Nuk334M
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| ! 071 12 13 156 1 DAV/bc 1 spray present continuously, with a high level of confidence 1 2 right in the dry well.
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| l l 3 4
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| -. 12 14 15 16 17 18 19 20 21 22 23 24 Q ,'st' ) '
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| 25 ACE-FEDERAL REPORTERS, INC.
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| 202-147-370l) Nationw ide Cos erage 80lL 336-N46
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| 071 13 01 157 1 DAVbur 1 So you have in effect two consecutive filters.
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| 2 So even a bypass goes through the spray, plus whatever 3 attenuation it might get by working its way down the gap or 4 in the building.
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| 5 DR. OKRENT: Would you remind me, the spray is 6 recirculating?
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| 7 MR. BERNERO: It could be. It depends on what 8 system is supplying it. It is most likely in this case an 9 independent source of cold water.
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| 10 DR. OKRENT: Where is the water accumulating?
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| 11 MR. BERNERO: It takes over a million gallons of 12 water to fill that torus, over and above the level it has 13 now.
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| 14 DR. OKRENT: How long is the spray going to be 15 on?
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| 16 MR. BERNERO: Continuously.
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| 17 DR. OKRENT: For how long?
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| 18 MR. BERNERO: Hours.
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| 19 DR. OKRENT: At some point you will fill up the 20 torus, I assume?
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| 21 MR. BERNERO: At 500 gallons a minute or 800 22 gallons a minute. You have about one and a quarter million 23 gallons to go to fill this space. That is a long time. If 24 that accident isn't over by then, you are in deep soup.
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| 25 DR. KERR: You are also losing maybe 500 gallons ACE-FEDERAL REPORTERS, INC.
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| mmm., ~ _ m- ,- -
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| 071 13 02 158 1 DAVbur 1 a minute due to evaporation.
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| 2 MR. BERNERO: Well, it depends. Well, no, by the 3 way, there is a technical error in the letter. It says that 4 1 percent decay heat is 10 minutes. It is really two to 5 three hours. 1 percent decay heat prevails at about two and 6 a half hours after shutdown, and you are down at that level 7 rather quickly, down to the 1 percent level.
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| 8 You are losing a little through evaporation. I 9 am taking no account of that. I am just adding fresh water 10 from the cooling tower basin, from the Connecticut River, or 11 whatever the source is.
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| - 12 DR. KERR: But you still lose 4- or 500 gallons a 13 minute, an appreciable amount.
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| 14 MR. BERNERO: It is a very long time. That was 15 one of the reasons for reducing the flow because if you 16 achieve anything like LPCI flow, you are going to much more 17 rapidly get into questions of do you really want to flood, 18 and I don't think so.
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| 19 DR. OKRENT: Let me ask, would you accept a 20 recirculating mode?
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| 21 MR. BERNERO: Yes. It is built right into the 22 procedures. If you have got the heat exchanger, you 23 recirculate and remove heat that way.
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| 24 DR. OKRENT: It is my impression that there were 25 concerns about recirculation at Three Mile Island.
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| ACE-FEDERAL REPORTERS, INC.
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| 202-34'-3700 Nationwide Coserage tuL336-(M6
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| r 159 g3071 13 03 .
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| 1 DAVbur 1 MR. BERNERO: Oh, yes, we aren't there yet. That 2 is the next degree.
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| 3 Core debris comes in two forms, and people forget 4 that. Core debris comes as that mysterious material we call 5 corium, which is metal and uranium oxide and that kind of 6 stuff, the stuft that would fall to the floor and be 7 congealed, we hope, by water, but also that water there is 8 now core debris. It is one-tenth or one-twentieth of a 9 curie per millimeter.
| |
| 10 Remember, TMI, the reactor coolant sample that we 11 got a day after the accident was 1 curie per millimeter 12 gross beta gamma. Now, a suppression pool reactor coolant 13 system in a BWR, multiply that by 29 -- or rather divide it 14 by 20. So you are talking about one-tenth or one-twentieth 15 of a curie per millimeter.
| |
| 16 That is core debris, and it shouldn't be run all 17 over the place. But keep in mind that in the typical Mark I 18 configuration the RHR system and its heat exchanger are 19 arranged close by in the RHR pump, ucually in the corner 20 room, and the heat exchanger not too far feca it, so that if 21 you did recirculate that water it would be in a very 22 controlled area and its leakage would fall down into the 23 corner room.
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| 24 And therefore, the debris control says make sure v
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| 25 that the water in the torus, which is core debris, can't go ACE-FEDERAL REPORTERS, INC.
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| mma,m x _ m- s_
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| l
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| n 071 13 04 160 1 DAVbur 1 anywhere offsite, outside, into the turbine hall, or into 2 some strange drainage system, even if the torus fails.
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| 3 In other words, you form a hydraulic boundary --
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| 4 the floor of the torus room, the floor of the corner 5 rooms -- which are accessible, and that is debris control 6 for the water, and then debris control for the corium is by 7 the spray and by the geometry which, if you get out, really 8 would go down into the torus room, and there is a pool of 9 water to quench whatever might reach there.
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| 10 Yes, Forrest.
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| 11 bR. REMICK: I am trying to understand Dave's 12 earlier question.
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| 13 Suppose you did run your small pumps at 800 14 gallons a minute and you do fill up the million gallons. It 15 would just go back into the dry well, wouldn't it, and there 16 would be nothing wrong with filling up the dry well?
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| 17 MR. BERNERO: In fact, the emergency procedures 18 l as presently drafted even encourage flooding this thing when 19 you start getting inco questions.
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| 20 Now, if you want to relieve pressure, if you 21 still have to relieve pressure, you are going to vent the 22 l dry well, and what kind of filtration are you getting? Is i
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| 23 i the submersion here enough? Is there a transition zone
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| ^
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| 24 where it wouldn't be enough?
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| ~
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| 25 Really, it is sort of a marriage of convenience, ACE-FEDERAL REPORTERS, INC.
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| 202- 347-3 NO Nationwide Cos erace Mn 346646
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| 071 13 05 161 l 1 DAVbur 1 reducing the spray flow rate. To make more systems 2 available as backups pushes this problem aside because it 3 takes so long to fill the torus.
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| 4 The vapor space of the torus is enormous, and it 5 takes a long, long time to get to that position. Therefore, I
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| 6 you are way down in the tail-end. You are almost in the j l
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| 7 cold shutdown. l 8 DR. OKRENT: I believe you said about 800 gallons i
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| j 9 a minute?
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| 10 MR. BERNERO: It varies with the plant. What 11 they actually deliver through the sprays you have to go dig
| |
| --s 12 out of some analysis. The pump that furnishes it is capable 13 of 10,000 gpm.
| |
| 14 DR. OKRENT: At 800 gallons a minute, you are 15 about, let's say, 5000 an hour, or a round number, 100,000 16 a day, 10 days, I sort of came out with.
| |
| 17 MR. BERNERO: Yes. That is the cold shutdown of 18 a core melt.
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| 19 DR. OKRENT: That is not the end of decay heat 20 generation; it is something to follow?
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| 21 MR. BERNERO: It is something to follow, but it 22 is a far slower damage control situation, a far less violent 23 situation than you have at the beginning.
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| ~1 24 Yes.
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| 25 MR. MICHELSON: At the subcommittee meeting, I ACE-FEDERAL REPORTERS, INC.
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| l 202-347-3700 Nationwide Coserage 80tL336446
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| 071 13 06 162 1 DAVbur 1 think you indicated you would find out what level indication 2 is available on the torus.
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| 3 Did you find that out?
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| 4 MR. BERNERO: N o .- I haven't had a chance to do 5 that. There are some. I have actually read in plant 6 procedures where they read as part of the procedures.
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| 7 NR. MICHELSON: I know there's some. The 8 question is the range.
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| 9 MR. BERNERO: The ones I have seen do measure wet 10 well level and even water in the dry well.
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| 11 MR. MICHELSON: There is some question about how
| |
| -- 12 rapidly it would be permissible to be flooding the 13 containment with the larger pumps because as you start the 14 flooding you lose the vapor suppression and the normal 15 capabilities. It may go down to unstable operations. Once 16 you fill that downcomer header partly with water, you may 17 have unstable condensing.
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| 18 DR. REMICK: Except he is spraying here from 19 l other pumps.
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| 20 MR. MICHELSON: That is later on. The question, 21 l' though, is related to the scenario early on and not later 22 on. He is not goirg to connect those fire pumps up for some 23 time.
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| N 24 MR. BERNERO: The fire pumps should be connected 25 immediately, or they would be preconnected.
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| ACE-FEDERAL REPORTERS, INC. >
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| a_.m x_ c_. -
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| 071 13 07 163 1 DAVbur 1 MR. MICHELSON: I thought there was some question 2 about at what point in time you bring them into play.
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| 3 MR. BERNERO: When the temperature in the dry 4 well starts to go up. They should be remote manual or by 5 simple manual procedure.
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| 6 Most of the owners I have talked to are talking 7 the remote manual -- you know, push a button.
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| j 8 MR. MICHELSON: The question, though, is at what 9 point in time, because I don't know how hot the water is, I f
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| I
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| ; 10 don't know how long they have vented, I don't know what got l 11 the core into the condition where it finally did melt. The
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| ! ,- 12 torus may already be at 200 degrees at that time.
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| 13 We don't know what is happening. I haven't seen 14 any scenario discussions.
| |
| 15 DR. MARK: Bob, would you be able to wind thi s 16 up in around 10 or 15 minutes?
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| 17 MR. BERNERO: Very much so.
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| 18 DR. OKRENT: And you are going to tell us 19 something about where seismic fits into this, did you say?
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| 20 MR. BERNERO: I was going to say, yes. You keep 21 asking me just as I get to the slide. l l
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| 22 DR. OKRENT: I like to be a straight man. .
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| l l
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| 23 (Slide.) !
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| 24 MR. BERNERO: Quality and design standards.
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| 25 These words are extracted directly from the ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(O Nationwide Cos erage 8(433MM6
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| m 071 13 08 164 1 DAVbur 1 generic letter. They are the conditions of these 2 requirements.
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| 3 The first one is should these be Seismic Category 4 1 or Class 1E, push buttons, or that kind of thing?
| |
| 5 These requirements are intended to be optimized 6 use of existing equipment, and therefore, of themselves they 7 do not bring in new quality standards.
| |
| 8 Nevertheless, you know the Seismic Category 2 9 over Seismic Category 1 issue. You don't put flimsy iron 10 beams above Seismic Category 1 pipes, or something like 11 that. You don't connect non-Class lE systems to Class 1E 12 electrical systems without appropriate isolation, so that 13 any adaptations or alterations are not going to be allowed 14 to compromise the quality of existing systems or 15 equipment.
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| 16 But going beyond, to add quality unique to 17 whatever these adaptations are, is not considered 18 appropriate because they are really optimized use of 19 existing equipment.
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| 20 So if you ask the question, what does this say 21 about seismic risk, how can one look and say I want 22 confidence, that that confidence doesn't dominate or bypass 23 the containment in any way?
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| 24 I just oad occasion to discuss this with Bob 25 Kennedy the day before yesterday at this conference in ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nanona.'le Coscrage 80fL336-6M6
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| | |
| i 071 13 09 165 i 1 DAVbur 1 Raleigh, North Carolina, and the discussion going on seismic 2 margins, you know, if you can't quantify the seismic risk, 3 perhaps you can enter the tunnel from the other end and say 4 up to what point can I have high confidence that there is a 5 low probability of seismic failure?
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| 6 For systems you can go rather high, into perhaps 7 .3 of a G or .4 of a G. You can get up to some fairly large 8 energetic earthquakes and still give an appropriate 9 walkdown, being assured that the systems are okay.
| |
| 10 Containments, if they are reinforced concrete 11 containments -- such as a BWR Mark II, or a large dry
| |
| , 12 containment, or the BWR Mark I, the principal dry well 13 structure of it -- those containments have inherent 14 capabilities that probably make them equal to or better than 15 the systems.
| |
| 16 The Mark I containment, it is reinforced 17 concrete, all right, the biological shield, but you have got 18 that vessel sitting inside that biological shield and kind 19 of rattling it, and you have an independent coupled torus 20 with all events.
| |
| 21 There may be a seismic failure of that 22 containment that you would encounter with the Mark I long 23 before you would encounter it with a Mark II containment r 24 because of what I will call that apparent vulnerability.
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| 25 The approach here does not provide any ACE-FEDERAL REPORTERS, INC.
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| 3)2-347-3700 Naaonwide Coserage 84 33MI,46
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| 071 13 10 166 1 DAVbur 1 mechanism to deal with that for the simple reason that there 2 is no obvious mechanism to deal with it that is available by 3 optimal use of existing equipment short of literally
| |
| } 4 redesigning the containment and backfitting it in some 5 really enormous way.
| |
| 6 If you look at the containment, there is nothing 7 that we can identify that would significantly the seismic J performance of this containment, and by that I mean the 9 passive resistance to seismic excitation, the coupling 10 between the dry well and the wet well. We can identify 11 nothing, and therefore nothing is provided.
| |
| 12 DR. OKRENT: Well, what you say under 13 implementation is that given the implementation of the 14 generic improvements of Mark I containments, there is no 15 need for an individual plant evaluation for containment 16 performance.
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| 17 And as I read this, this could write off any need 18 to look at the containment capability, given an earthquake.
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| 19 It could be read that way.
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| 20 As of now, I have not seen any written study of 21 l the Mark I's. Because I am sure they are not all the same 22 with regard to seismic, they have to be located at a variety 23 of sites, et cetera, et cetera, I have no feel for what kind 24 of f ailures may occur that may lead to early containment 1
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| 25 failure or not. l ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Cos erage Nn336-6646
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| s 7
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| 9071 13 11 167 1 DAVbur 1 I, for one, am not willing to just say, throw up 2 my hands and say it may be bad and there is nothing we can 3 do about it without looking.
| |
| 4 This is what was said in 1966 about the whole 5 core melt thing, you may remember, and for literally then 6 maybe almost 15 years it was the situation that prevailed.
| |
| 7 People said, well, containments are going to go given core 8 melt, until suddenly there was the reversal.
| |
| 9 So I, for one, need to see a good look from the 10 seismic point of view.
| |
| 11 One can talk here, if you wish, about an opinion
| |
| .-- 12 based on what one now knows.
| |
| 13 DR. KERR: Dave, are you assuming that these 14 containments have not been designed for seismic?
| |
| 15 DR. OKRENT: They have been designed for an SSE, 16 but everything here is beyond design basis. You don't get 17 to core melt.
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| 18 DR. KERR: Is that the context from which you are 19 coming?
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| I 20 DR. OKRENT: That is the context.
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| 21 MR. BERNERO: I can't give you an answer other 22 than the one I gave you.
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| 23 DR. OKRENT: But you are writing off possibly, 24 with the words you have got there, any further look from 25 what I will call the external event. There may be some l
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| ACE-FEDERAL REPORTERS, INC.
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| mme- ~ _ m_ - I s
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| 071 13 12 168 1 DAVbur 1 other external events that are of interest. But certainly 2 seismic strikes me as one that needs to be looked at, and it 3 has been too long, in fact, that we haven't had the benefit 4 of a good evaluation of the Mark I's from the seismic point 5 of view.
| |
| 6 MR. BERNERO: I would just point out on the 7 implementation Dave picked up on, this closes the individual 8 plant evaluation for containment performance or is intended 9 to, and the time, nine months, means that it would be 10 implemented by anything like a range of nine months from the 11 effective date to perhaps as much as two years.
| |
| 12 If someone has a long fuel cycle and enters the 13 refueling eight months after the effective date, we are 14 going to get one more fuel cycle plus eight months, and you 15 know it might be as much as two years.
| |
| 16 But that was chosen in order to have an orderly 17 implementation without competing risks of rushed and sloppy 18 work.
| |
| 19 There are some words in the severe accident 20 policy statement --
| |
| 21 MR. MICHELSON: Before we get to that, could you 22 clear up a point for me?
| |
| 23 Having decided to put this system in and now having it available, what is the decisionmaking point for
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| ~
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| 24
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| )
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| 25 the operator? When does he decide to turn it on?
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| ACE-FEDERAL REPORTERS, INC.
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| 7 071 13 13 169 1 DAVbur 1 MR. BERNERO: Symptoms. He follows the symptoms 2 in the reactor coolant system and the containment, the 3 containment pressure and the containment temperature.
| |
| 4 MR. MICHELSON: And what numbers do you have in 5 mind? Design, twice design?
| |
| 6 MR. BERNERO: The pressure of interest -- this is }
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| 7 for the venting, of course -- the pressure of interest is 8 either as low as design pressure or as high as 1.5 times 9 design pressure for venting. That is in the letter, and the 10 temperature is plant specific, but it is usually --
| |
| 11 MR. MICHELSON: That is going to be the point at 12 which you would first start this auxiliary spray?
| |
| 13 MR. BERNERO: Yes. His procedures tell him under 14 this symptom at this temperature start spray.
| |
| 15 MR. MICHELSON: Up to that point he is following 16 his conventional mitigating steps?
| |
| 17 MR. BERNERO: I might add something here that is 18 rather significant. There is already an evolution among 19 owners, BWR owners, Vermont Yankee the first one. To 20 containment vent during an event -- this is the noble gas 21 release -- is not something they will permit their operators 22 to do without authority.
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| 23 Vermont Yankee has already said publicly they 24 intend to finish their procedures now the way the French do
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| {'
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| 25 it. The French operator has an EOP to go into an incident ACE-FEDERAL REPORTERS, INC.
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| . . .. .. . = _ . - .. -. . . .~ -. . . . . . - .
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| 071 13 14 170 1 DAVbur 1- procedure and accident procedure or a loss of function.
| |
| .2 procedure, but he is not authorized to vent the
| |
| . 3 containment.
| |
| 4' The technical support center and above must 5 authorize that, and that is exactly the tone that Vermont 6 Yankee has taken publicly already.
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| 7
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| 23 O 25 ACE-FEDERAL REPORTERS, INC.
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| 071 14 01 171 1 DAV/bc 1 We may very well end up that way. And that 2 decision, since it's an evolutionary thing some hours into 3 the sequence, would be a reserved decision.
| |
| 4 DR. OKRENT: When you're talking about things 5 that are not designed for class one conditions, I recall 6 vaguely a study funded by the NRC and done by some group in 7 California using something called a chilled service system 8 which, if I remember correctly, would also get at least some 9 fraction of the noble gases.
| |
| 10 Maybe I'm wrong.
| |
| 11 MR. 1ERO: Some cryogenic, maybe.
| |
| 12 DR. OKRENT: Yes, and for which their estimate 13 was $2.5 million. In other words, venting is here through 14 something like that and high, but in this case, not taking 15 the full noble gas load as a release and being much more 16 confident on other things.
| |
| 17 MR. BE RNERO: I'll show you a cost benefit thing 18 in a moment that I think is a better vehicle to address 19 that. Let me take that up.
| |
| 20 lj MR. EBERSOLE: You said at Vermont Yankee they 21 l*
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| can't vent unless they go through --
| |
| 22 MR. BERNERO: The decision has to come from the 23 boss.
| |
| ' ~
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| 24 MR. EBERSOLE: Is that strictly post-core damage 25 failure?
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-37M Nationwide Coserage En33MM6
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| 071 14 02 172 1 DAV/bc 1 MR. BERNERO: Oh, yes. Dirty venting. Clean 2 venting, they have a procedure.
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| 3 MR. EBERSOLE: Okay.
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| 4 MR. BERNERO: But if it's high activity level in 5 the containment, they must get authorization.
| |
| 6 (Slide.)
| |
| 7 The generic letter postulates two mechanisms of 8 justification. Why is this justified?
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| 9 First is that it is needed for safety, needed for 10 safety in the sense that it is not a tolerable range of 4
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| 11 debate. If the fraction of core melts resulting in large 12 release is arguably somewhere in the range of 10 percent to 13 90 percent, that's just not good enough.
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| 14 And at the inconclusion of these enhancements, 15 you know, these more reliable sprays, and venting and so 16 forth, could at least shift that range of debate into the 17 next order of magnitude below. It's not clear what kind of 18 improvement. We don't have any good, well-developed 19 quantification of it.
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| 20 l i But, that shifting the range of debate to some I
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| 21 greater, or I should say lesser fraction resulting in a 22 large release, or greater confidence of mitigation, and that 23 it can be justified, this is potentially interpretable as
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| ,~, 24 Commis*..on policy.
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| 25 It is J uly 16, 1986, the Commission's response to ACE-FEDERAL REPORTERS, INC.
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| n w.,. ~ w c- -,-
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| n 071 14 03 173 1 DAV/bc 1 Chairman -- or Congressman Markey, or whatever the House 2 Committee is that he chairs, and the question was about a 3 BWR with Mach I containment.
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| 4 He referred to Harold Denton's speech citing a 90 5 percent chance of failure. Again, that's a 90 percent 6 fraction of core melts resulting in a large release -- is 7 that acceptable?
| |
| 8 And this is the Commission's answer. I reproduce 9 only the first part of it, and it says:
| |
| 10 "The likelihood of core melt should be very low 11 and, in addition, there should be substantial assurance that w 12 the containment will mitigate the consequences."
| |
| 13 Then it went on to refer to other questions, and 14 things like that. So one can argue on those grounds you 15 can't stand up with a straight face and tell me 10 percent 16 to 90 percent is substantial assurance that the containment 17 will mitigate.
| |
| 18 And perhaps we can feel that assurance if the 19 debate is between 1 percent and 10 percent. That's one 20 ground.
| |
| 21 The other ground, consistent with the severe 22 accident policy statement, is cost benefit analysis.
| |
| 23 (Slide.)
| |
| '' 24 And you can get in a great debate. The owners 25 group kindly provided some costs for the envisioned changes.
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-3XO Nation *ide CO%ef age NM 3364M6
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| y-071 14 04 174 1 -DAV/bc 1 The range of costs they gave was $.7 to 2.2 2 million dollars per plant. Obviously, I prefer to look at 3 that as, let,'s'say, $3 million a plant, rounded upward a 4 little bit.
| |
| 5 If you went out to implement it, you might run 6 into'a hardware problem you didn't foresee. And it's very 7 easy to incur an additional half million dollars or so 8 expense.
| |
| 9 Also, we're in a context where emergency 10 procedure guideline, revision and implementation is free.
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| 11 It's not really free. It's quite costly. But those are
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| - 12 separate requirements. They're like overhead, you've got to 13 do them anyway.
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| 14 And that requirement is when we're through with 15 the emergency procedure guideline, Rev. 4, we should be 16 .there with appropriate accident management and we're very 17 close now.
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| 18 So that cost is not really counted in here.
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| 19 You're only really counting the cost of spray enhancement 20 and the cost of venting improvement. We did a base 21 calculation and a series of others. I'm using the old
| |
| [ 22 terminology here: frequency of core melt, conditional 23 containment failure probability before the enhancements, and
| |
| ?
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| 24 to the enhancements, the averted loss per year monotized.
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| }
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| ( 25 And then a present value of averted loss calculated two i
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| ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(U Nationwide Coserage 8(n33MM6
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| 071 14 05 175 1 DAV/bc 1 ways.
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| 2 DR. REMICK: What's the averted loss there?
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| 3 MR. BERNERO: The averted loss was taken as the 4 paper says. If you go to the Strip Report, remember the 5 Sandia siting study and the site by site analysis of citing 6 source term releases and their economic costs, you can 7 identify for a large release -- the numbers vary from site 8 to site -- but a good representative value is 10 to the 7th 9 person rem per large release as a typical value.
| |
| 10 I used that and multiplied it by a thousand 11 dollars a person rem. Then, of course, it's simple 12 arithmetic.
| |
| 13 Frequency of core melt held constant times delta 14 failure probability times 10 to the 10th dollars. And that 15 gets you an averted loss per year. You know, it's a 16 frequency of averted loss.
| |
| 17 And to get a present value, you have a 18 philosophical question. You're monotizing human life or 19 human health. Should you have a discount rate associated 20 with such monotization.
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| 21 DR. LEWIS: Yes.
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| 22 MR. BERNERO: I say yes also. But, nonetheless, 23 the argument is made occasionally, so I do it two ways. I
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| ' ~ 24 multiply by 8, which is a 12 percent discount rate, present 25 worth at 12 percent. Then I multiply by 30 the remaining ACE-FEDERAL REPORTERS, INC.
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| -m.) umumge m3m
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| ]
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| 071 14 06 176 1 DAV/bc 1 life of the plant, 30 years, with no discount rate. So you 2 can take your pick.
| |
| 3 DR. REMICK: Let me point out you're not 4 discounting deaths, you're discounting the dollars, which 5 makes sense.
| |
| 6 MR. BERNERO: No, I'm discounting the monotized 7 value of health effects. Now I have not considered economic 8 effects, but there is a reference in the letter. Economic 9 effects can swamp this calculation. They can easily be 10 10 times greater than the monotized health effects.
| |
| 11 So the base calculation uses a cautious 10 to the 12 minus 4 per year f requency of core melt and says: Let's sit 13 like Solomon. If NUREG 1150 comes out with 90 percent and 14 IDCOR comes out with 10 percent, we'll call it 50 percent.
| |
| 15 And let's say it's worth a decade. Actually, 16 it's not terribly sensitive to this number, as you can see 17 yourself. Going down a full decade isn't necessary. The 18 averted loss per year, you say, well, the $3 million a plant 19 or a little less, it's worth it.
| |
| 20 Lower frequency of core melt. You drop down to 21 be debatable. Certainly, debatable. Slightly below being 22 worth it. Less change in the containment.
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| 23 If, instead of dropping down by a factor of 10, t') 24 you drop only by a factor of 5, at one significant figure,
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| ( '
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| 25 you ccn't even see it. If you had a better containment to ACE-FEDERAL REPORTERS, INC.
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| 202-347-37(V) NationwiJe Cos erage
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| * 433M646
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| 071 14 07 177 1 DAV/bc 1 start with, what if Peach Bottom, IDCOR was right to begin 2 with? You'd come down still in the debatable range.
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| 3 If you use an optimistic calculation -- by that, 4 I mean a low core melt frequency of the better end for the 5 containment to start, you come out slightly less than 6 worthwhile.
| |
| 7 And of course, if you use the pessimistic 8 calculation of a high core melt frequency, the 90 percent to 9 start with, then come down, it's clearly worth while.
| |
| 10 The judgment that's made is it's a justifiable 11 backfit under the backfit policy. Therefore, go ahead and 12 do it, and there is a sufficient exploration of uncertainty 13 here to develop confidence in that choice.
| |
| 14 If you would go to something else, Dave, if you 15 would go to a cry 3 genic capture of the noble gas activity, 16 what you have to do now is filter out the person rem of 17 noble gas and justify that additional cost. 'And it just 18 isn't worth it.
| |
| 19 You see, what we're justifying here is a cost in 20 the same order of magnitude as the cost of an additional 21 cryogenic filter. It just simply isn't worth it to throw 22 any more bells and whistles at this.
| |
| 23 DR. OKRENT: I think if you go through the
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| '~
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| '1 24 procedure that you have just done, that's the result you'll 25 get. However, were such an accident to occur and let's say ACE-FEDEPAL REPORTERS, INC.
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| 202-347-3700 NatiOM%idC rmCragC Edk 33fF6l46
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| --< ~
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| 071 14 08 178 1 DAV/bc 1 you had implemented the things that you're recommending, and 2 there had nevertheless been this full release essentially of 3 noble gases, and the question at the Presidential Commission 4 was asked: Was there nothing you could do for the noble 5 gases?
| |
| 6 One said, well, if we spent another, let's say, 7 $2.5 million, we might have cut those down by 90 percent.
| |
| 8 And you say, This is a plant that would have cost 9 $2 billion to replace at the time it would have cost $2 10 billion to build that chill filter thing. And you'd say, 11 Yes.
| |
| 12 Now, tell me, what is this cost benefit you're 13 talking about? Because I really don't understand.
| |
| 14 MR. BERNERO: Dave, that argument was the very 15 same line of logic that had us debating like a bunch of 16 antic fools for a year, about 50,000 curies of krypton 85 in 17 the TMI building. We wouldn't even open an airlock for a 18 measurement because if 40 curies of krypton 85, we're 19 talking with the noble gases about a potential one hour 20 after shutdown of high dose, but doses that are down in a 21 , range with a high release, clinically detectable effects or 1
| |
| 22 lower are substantially lower than that.
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| 23 And you would be integrating person rem at the
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| ( ~x 24 very, very low end of exposure, which I don't think is a 25 responsible use of national resources. And that's why I ACE-FEDERAL REPORTERS, INC.
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| 202-347-3700 Nationwide Coverage NG33&fM6
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| F" 071 14 09 179 1 DAV/bc 1 don' t do it.
| |
| 2 DR. OKRENT: I'm just saying there may well be a 3 public perception that's very different.
| |
| 4 MR. BERNERO: That was the same public perception 5 that said that we should vent the krypton 85 at TMI on a 6 2,000 foot hose attached to a tethered balloon. And that's 7 where we have a witch doctor, that's not science.
| |
| 8 (Laughter.)
| |
| 9 DR. OKRENT: I'm sorry. I don't want to mix the 10 small doses.
| |
| 11 MR. BERNERO: But, even these doses for that 12 short time.
| |
| 13 DR. OKRENT: Secondly, at the moment, not having 14 looked at the possible advantages, let's say, of something 15 like a chilled filter, I'm not an advocate of a chilled 16 filter. It's just something I recall was paid for by an NRC 17 study.
| |
| 18 But it may be that if and when you look at 19 earthquakes, you will find it has an advantage there. I 20 don't know until one looks.
| |
| 21 So I'm reluctant to act as if one has enough 22 knowledge to close the door.
| |
| 23 MR. BERNERO: Dave, you just referred to the
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| - s 24 frustrating discussion of core melt. Since 20 years ago, 25 1966, you go back farther than I do. I reached my ACE-FEDERAL REPORTERS, INC.
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| 202 347 37(X) Natioriwide Coserage Rn34(4,46
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| 071 14 10 180 1 DAV/bc 1 threshold of frustration quite a while ago.
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| 2 DR. MARK: Bob, I think you've gone through the 3 picture for us.
| |
| 4 MR. BERNERO: I just was putting up the 5 schedule.
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| 6 (Slide.)
| |
| I 7 DR. MARK: You have a mind to send a letter up to 8 CRGR and subsequently to the Commission.
| |
| 9 MR. BERNERO: ~he CRGR is actually December 22nd.
| |
| 10 There's a slight adjustment. And presuming generally 11 digestible comments from you and from the CRGR, we would
| |
| -m 12 prepare an information p aper for the Commission and just 1 13 tell them this is what we intend to publish for comment, 14 unless you object; because, remember, this would be a staff 15 action, not a Commission action.
| |
| 16 It would sort of be like tacit consent on their 17 part.
| |
| 18 DR. MARK: You really would like to have us say 19 go ahead, or slow down, or what?
| |
| 20 MR. BERNERO: Or whatever. Constructive 21 ' criticism. If you don't agree, I'll take your names and 22 I'll get you.
| |
| 23 DR. MARK: I think I would like to cut this off
| |
| '' 24 i here.
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| 25 DR. OKRENT: Can I ask just one question?
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| ACE-FEDERAL REPORTERS, INC.
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| mm,.m, ~ _ m- seam
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| i 071 14 11 181 1 DAV/bc 1 DR. MARK: As long as it's short.
| |
| 2 DR. OKRENT: It's very short. It's for a future 3 answer. You're familiar with the paper at the ANS meeting 4 by Chu and Stoyanov about a new scenario for intersystem 5 LOCAs in BWRs at the last ANS meeting?
| |
| 6 MR. BERNERO: No, I'm not familiar with that. I I 1
| |
| 7 will look into it.
| |
| 8 DR. OKRENT: At some future time, let me know of 9 its import, if any.
| |
| I 10 DR. MAR": I want to call on Mr. Pickens, but f
| |
| before that, Mr. Remick has something he wishes to tell us. f j 11 x 12 DR. REMICA: Bob, this is intended to be a 13 constructive comment. Your averted loss present value. I j
| |
| 14 spent a lot of time when you were talking trying to figure 15 that out. Why is it a ratio? Really, I think it would be 16 much clearer if you had averted loss present value method A, 17 method B.
| |
| 18 MR. BCRNERO: Okay. I didn't intend it as a 19 ratio. I intended it as true values.
| |
| 20 DR. MARK: Thank you, Bob.
| |
| 21 Mr. Pickens, you have skipped an important 22 meeting, I believe, in order to be nere.
| |
| 23 MR. PICKENS: They're finished, so I have that I
| |
| f' 3 24 latest input. I'11 ccme up here.
| |
| 25 DR. MARK: Can you tell us what you need to in l ACE-FEDERAL REPORTERS, INC.
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| mm., ~ _m_ . s<, o -
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| | |
| I 071 14 12 182 1 DAV/bc 1 10 minutes?
| |
| 2 MR. PICKENS: Yes, I can cover it quickly. I 3 brought 40 copies of the one slide I'm going to be throwing 4 up, pass it around. We can put some in the back of the 5 room.
| |
| 6 I just came from a NUMARC working group meeting.
| |
| 7 I didn't have to miss any of it today; I managed to get 8 through in time.
| |
| 9 What I wanted to open with was just some quick 10 comments about the utility perspective on what the current 11 program is and why.
| |
| 12 Indeed, NUMARC and the BWR owners group have 13 taken on a parallel program to Bob Bernero's, and then give 14 you a couple of quick comments on some of the aspects of 15 Bob's presentation.
| |
| 16 The statement we recently made in a presentation 17 to the Commission in a briefing which they asked for was 18 that utilities do not lack confidence in the capability of 19 the Mach I containment to meet the challenges of a severe 20 accident. f 21 I think this is confirmed, indeed, by the 22 Commissioners themselves in the severe accident policy 23 statement, where they stated that based on the current
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| ~'
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| 24 information, that they felt the plant was safe.
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| 25 They did identify in the severe accident policy ACE-FEDERAL REPORTERS, INC.
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| m m.m, ~ m_ m o- - > > -
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| r- -
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| t 071.14 13 183 1 DAV/bc- 1 that if new information or issues were brought forward, they 2 should be considered an appropriate action should be taken.
| |
| 3 We agree with that. I guess that we would have
| |
| ~4 to construe that right now though we don't see new 5 information being brought forward. We see a refinement of 6 some old information that was available at the time that 7 that judgment was made on plants being safe.
| |
| 8 And, indeed, the refinements say maybe it didn't 9 go down f rom whatever that number was in WASH-1400 as low as 10 we would have liked it, or that, indeed, it is going down.
| |
| 11 The reason then that we have decided to take on a 12 program and are participating in this process, and we've 13 been trying to work with Bob and work with this committee, i
| |
| 14 the Commissioners, and things, is that, in our opinion, 15 there are uncertainties in the minds of some which don't 16 allow them to state unequivocally that the same conclusion 17 which we have reached -- which is that we have confidence in 18 the Mach I containment in severe accidents when the 19 challenges are there.
| |
| 20 21 22 23 24
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| (~>T s_
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| 25 ACE-FEDERAL REPORTERS, INC.
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| 202-347-3XX) Natkmaide Coverage %D 336f4M
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| | |
| 071 15 01 184 1 DAVbw 1 What we would like to do in this program is to 2 help bring them to the point of being able to make the same 1
| |
| 3 conclusion which we make. In order to do that, we've 4 identified the program, the slide which we've handed out.
| |
| 5 (Slide.)
| |
| 6 The overall objective of the program we've put 7 together is to evaluate containment integrity and evaluate 8 potential imnprovements to minimize off-site releases for 9 severe accident conditions beyond the design basis accident 10 within an appropriate cost benefit goal.
| |
| I 11 I mentioned when I was before the subcommittee on f 12 Tuesday, they asked me for some quick comments. We have a 13 lot of people that we are responsible to in terms of being 14 utilities -- ratepayers, stockholders, public utility 15 commissions, and we have to demonstate that we are 16 effectively spending the money which we are investing into 17 these plants.
| |
| 18 I think the cost-benefit goal is appropriate, and 19 I have to say, I think Bob has been trying to put together 20 an appropriate benefit analysis to be put through.
| |
| 21 We do have some comments on it, on whether or not 22 we think it is appropriate. We haven't gone through the i
| |
| 23 complete process. We don't have it ready to put before you
| |
| ~^ 24 today, but we do think it needs to be done in an appropriate {
| |
| 25 cost-benefit goal.
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| ACE-FEDERAL REPORTERS, INC.
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| mm., ~ _ _ - --
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| | |
| P' 071 15 02 185 1 DAVbw 1 The next step in our process is to identify the 2 challenges to containment. This list that you see before 3 here on the seven items is a partial list. You can see the 4 asterisk which says, other issues to be added, and indeed, 5 on the subject of, say, steam explosions, there's been a 6 suggestion by some members that we should put forward to 7 make this a comprehensive document, all challenges to the 8 containment, even those which we have under IDCOR and other 9 industry efforts identify and feel have closed, so that this 10 will be a comprehensive document of challenges to the Mark I 11 containment and how we feel they have been dealt with. And
| |
| ~ 12 if there are improvements that need to be made from the I 13 challenges which are identified under step 2, we will then 14 go to all of the work that's been done on severe accident 15 sequences.
| |
| 16 What we plan on doing is, we plan on using the 17 IDCOR work. We plan on using any plant-specific PRAs. We 18 would like to go out and talk to the people at the various 19 National Labs, find out what their concerns have been. What 20 we want to put together is a complete set, whether we agree 21 with them or not, a complete set of the most severe 22 dominant, severe accident sequences, so we can really see 23 what we are talking about, in terms of making everybody feel
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| ~'
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| . ; 24 comfortable, once and for all, that we are going to close 25 the issue of Mark I's capabilities under severe accidents.
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| ACE-FEDERAL REPORTERS, INC.
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| 3-4 ~_ m <- ->-
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| 071 15'03- 186 l' DAVbw 1 We will then assess the plant's abilities to meet 2 those challenges,-identify the vulnerabilities and then
| |
| :3 propose alternatives to address the vulnerabilities.
| |
| : 4. The alternatives might turn out to be identical
| |
| -5 .little ones that Bob Bernero has presented. Some of the 6 work we-have seen has identified the drywell sprays as being 7 critical, as they have identified venting as being 8 critical. We might not identify any fixes. We are trying 9 to go into this with a very open mind, at this point, saying 10 we might confirm, Bob, we might not. We might come up with 11 some, we might come up with more. Then we will go through 12 and evaluate the alternatives.
| |
| (-)
| |
| 13 Now Bob referenced earlier the cost estimates 14 which have been provided, the 700,000, the 2.2 million, and 15 indeed, those were put together by utilities as part of the 16 process of the IDCOR Owners' Group work in responding to 17- Bob's request on June 16th, when we went in.
| |
| 18 I would have to qualify those, that those were 19 order of magnitude type cost estimates. The question which 20 I received on Tuesday on the subcommittee was, what do I 21 think about those?
| |
| 22 My gut feel is that they are perhaps a little bit 23 low. The number that we felt comfortable with in that 24 report is, it would cost something around the order of SS 25 million. That did include core debris barriers. If you ACE-FEDERAL REPORTERS, INC.
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| 202 Nationside Coserage 863346M6
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| - ~ _ _ , _ ._
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| _-347-3700_ _.._._ _..__-.~_..._ _ _ - . . . _ . - _ .
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| | |
| E 071 15_04 187 1 'DAVbw 1 took'those out, it is going to drop down significantly, but 2- I think that.it still might be slightly' higher than .7 to 3 2.2.
| |
| 4 It is very difficult.to use those numbers as 5 absolute numbers. Evaluate the alternatives, using the 6 accidents sequence, the benefit that we see, the risk 7 reduction against the cost.
| |
| 8 What we are trying-to do is, working within 9 an appropriate cost-benefit goal, realizing there is a 10 NUMARC working group looking at safety goal, cost benefit 11 and that type of thing, we are going to work to put our p 12 report in the. unit such that when we finish, that group l,_/
| |
| '13 inside NUMARC can, with their current status and their 14 current position get the results of our report, crank it 15 through a cost benefit and then we can present to NUMARC, 16 for their action, some proposal, initiative, whatever.
| |
| 17 The Owners Group would present this to the NUMARC 18 working group, and we would work our way back up through the 19 process of NUMARC to identify whether there were any 20 initiatives that the industry would then deem they would 21 take on.
| |
| 22 That is our basic program.
| |
| 23 The only other couple of points that I wanted to 24 go over, were perhaps the IDCOR number of 20 percent on the 25 conditional containment failure probability. I think that ACE-FEDERAL REPORTERS, INC.
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| 202-347-37H) Nationwide Coserage an3E646
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| I 071 15 05 188 1 DAVbw 1 there are those inside of IDCOR who feel that it could be 2 identified as lower, and it could be going down as low as 5 3 percent. It is not a firm number at this point, I don't 4 think. I think if it is moving anywhere, it is moving 5 down.
| |
| 6 NUREG 11.50 and the 90 percent. There was a Wall 7 Street Journal back in July which came out, which said, yes, 8 it was going to confirm the old WASH-1400 results. There 9 was a lot of action taken on the part of the industry at 10 that point, a lot of phone calls that went between the 11 Commissioners. It comes down to, in our understanding, two 12 key parameters. That is the ultimate pressure capability of 13 the containment and how does the corium act?
| |
| 14 I think that those two key parameters, depending 15 on how the final decision it made to incorporate those into 16 NUREG 11.50, will have a great deal to do with the 17 conditional f ailure probabili cy that it finally results in.
| |
| 18 In fact, there is EPRI work going on in the area 19 of corium phenomonology, and there is a program being 20 sponsored underneath the Owners Group taking a look at the 21 ultimate pressure capability of the Mark I containment. It 22 is currently being used as 135 for the pressure capability.
| |
| 23 Bob identified that it might go much higher, in fact, indeed
| |
| ~1 24 l even up to three times. I think that some of the
| |
| ) l 25 preliminary work tnat I have seen says, yes, it is going to ACE-FEDERAL REPORTERS, INC.
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| .n., ,_-- .o-
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| | |
| ~
| |
| 5 l
| |
| 71.15 06 189 l' DAVbw 1 'go much' higher, if those.two key parameters are' turned 2 'aroundi'and you don't assume that the corium is going to 3 quickly reach the liner. If you don't -assume that you are 4 going to reach that pressure of the 135 or whatever it was 5 raised up to. It turns around the result drastically, in 6 NUREG 11.50, to whereas, instead of reporting-90 percent, it 7 might come.out and report 10 percent or 30 percent or
| |
| .8 something much lower.
| |
| 9 I thinkt that is key in considering what.we are 10 putting together here.
| |
| 11 One comment on the IPE and the question of 12 seismic capability of containment. The IPE is not s
| |
| : 13. structured right now to address the seismic capability of 14 the containment.
| |
| 15 DR. OKRENT: I am aware of that, but I am curious 16 that the BWR Mark I Owners Group haven't, of their own 17 initiative, long before this, tried to evaluate the seismic 18 capability of the Mark I rather well. If I were such an t
| |
| 19 owner, I know I would have been glad to pay what is a 20 relatively modest amount of money, compared to what it costs
| |
| - 21 for a day of downtime.
| |
| 22 MR. PICKENS: With the amount of work that's gone
| |
| , 23 into the Mark I containment programs, as such, over the
| |
| ! 24 years, I think that we feel very comfortable with the 25 seismic capability of the Mark I containment, and we don't l
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| l ACE-FEDERAL REPORTERS, INC.
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| 2rC 347 370) Nationwide Coscrage 80lk33M646
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| 9071 15 07 190 0 1 DAVbw 1 see a need to be going into it.
| |
| 2 And there is a Seismic Owners Group and there is 3 a whole seismicity issue that is being addressed at another 4 place, and the utilities are participating in that.
| |
| 5 DR. OKRENT: There is a seismicity issue that is 6 being examined, I agree, by EPRI, but we are still acting, 7 as far as I know, in any published form, that a good 8 evaluation or maybe even a rough evaluation of the seismic 9 capability and failure modes for Mark I's, I don't know if 10 they are all the same, or there are important differences.
| |
| 11 The other thing I am curious about is, whether,
| |
| -, 12 in your evaluations, you will allow for things like we heard 13 about at this meeting -- degradation a la Oyster Creek, 14 degradation of some portion of the containment. In this 15 case, it was found -- I don't know what degradation exists 16 that we don't know of, and how this may affect failure 17 pressure and failure place. Perhaps, significantly.
| |
| 18 MR. PICKENS: If there were indications that 19 pointed to degradation being a generic problem, and at this 20 point, they point to its not being a generic problem for 21 degradation of the drywell liner, we would certainly 22 , incorporate that.
| |
| I l
| |
| 23 DR. MARK: I think the laast question on which r3
| |
| ^
| |
| 24 you didn't comment, Mr. Pickens, do you have a time scale in 25 l mind?
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| I ACE-FEDERAL REPORTERS, INC.
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| :ewm s_ ac c-, ~ ~ ~ , ,
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| 071 15 08 191 1 DAVbw 1 MR. PICKENS: We discussed the schedule at the 2 meeting this morning, and it is currently anticipated that 3 we would have a final report on March 31st, and it is at 4 that point that we would then be working through NUMARC to 5 propose any industry initiatives that we are going to take.
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| 6 DR. MARK: Is that a pretty firm date?
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| 7 MR. PICKENS: Yes. We feel pretty confident in 8 being able to meet the March 31st date.
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| 9 DR. MARK: I think if you are willing, I would 10 like to have us leave it there, except for the things we 11 have to decide for ourselves.
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| 12 DR. OKRENT: I would like to offer one comment to 13 the last response.
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| 14 It seems to me, when you are looking at things 15 probabilistically, you don't wait until you have a clear 16 indication that there is an important degradation effect, in 17 other words, that the probability is 1 or 1/2 or so forth.
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| 18 it goes counter to the whole idea, i 19 I will leave it at that.
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| 20 DR. SIESS: The whole idea of what?
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| 21 DR. OKRENT: Of estimating risk.
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| 22 , DR. MARK: We've had Mr. Bernero tell us the l
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| 23 j line of thought he's been building up and following. We
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| ''N 24 have had a picture that NUMARC is actually applying itself l
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| 25 to similar problems and hopes to have something firm, solid, ACE-FEDERAL REPORTERS, INC.
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| _., s _ <- - ;
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| 071 15 09 192 1 DAVbw 1 put out in four months. And Bernero is talking of going 2 ahead on a rather more rapid time scale, and we are being 3 asked to say something on the subject, if we possibly can, 4 this week.
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| 5 I think we've really got the whole picture.
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| 6 DR. OKRENT: Can I ask one or two things of the 7 chairman, the subcommittee chairman?
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| 8 Let's say we have the NUMARC report, where they 9 have used methods, and so forth, that the Staff considers to 10 be transparent, or will we then be in that situation, where 11 they have used a code that the Staff has reviewed here and 12 there and so forth.
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| 13 You understand what I mean. So there is then 14 another six-month period, or whatever.
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| 15 DR. MARK: I hear ya. I don't know.
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| 16 DR. OKRENT: I don't either.
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| 17 Apparently, there will not be a seismic input 18 from NUMARC. I heard nothing that indicate --
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| 19 DR. MARK: There wasn't any seismic input from 20 the Staff either.
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| 21 DR. OKRENT: I fought them equally.
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| I
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| ( Laughter. )
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| 22 l 23 MR. EBERSOLE: Carson, let me ask you a {
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| i
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| ,~' 24 l question. The proposition has been made that we are going
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| \_ l 25 ' to have what is called a source of water that is going to ACE-FEDERAL . REPORTERS, INC.
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| m.m., ~ ~ ~ - m .e,_
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| l
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| c.
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| 071 15 10 ,
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| 193 1 DAVbw 1 go into a spray system which will spray.
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| 2 The question is, if I've got water to put 3 anywhere, I am going to put it on the core first, whether it 4 is on the floor or not.
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| 5 I am going to try to put it on where it ought to 6 be, which is in the vessel. If it is gone to the floor, 7 then there must be a hole for me to let it get in there 8 also.
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| 9 Is there, in parallel with this proposition, that 10 I have that same sort of water excess to fuel to core, 11 not before it gets on the floor, not after it gets on the 12 floor, but before it gets on the floor?
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| 13 DR. OKRENT: At what pressure, Jesse?
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| 14 MR. EBERSOLE: That is a question that we ask, at 15 what pressure are we going to assure ourselves that we are 16 going to go to the primary vessel, so that the pressure in 17 it is the same as in the drywell?
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| 18 DR. MARK: Look. I think we are really at the 19 spot where we don't know.
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| 20 MR. EBERSOLE: Certainly, that would be a step to 21 take prior to cooling it on the floor.
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| 22 DR. MARK: We don't know, I believe, what answers 23 deserve to be given.
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| MR. BERNERO: May I, Mr. Chairman? I have two
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| , 24 25 answers to that question.
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| ACE-FEDERAL REPORTERS, INC.
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| :e m. m ., sm_,m -, s ,s n- i
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| 1 071 15 11 194 1 DAVbw 1 One, this activity is consciously segmented or 2 bining the problem to be containment only, and therefore, 3 does not consider enhancements of the AES or the relieve 4 valve system. Nonetheless, I will give you a very specific 5 example. I mentioned earlier that Vermont Yankee plant has 6 that fire pump.
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| 7 The procedures set for Vermont Yankee, as they 8 should logically do, give the operator the priority 9 determination, that if you've got the water, and you've got 10 it in that pipe, the first choice is to put it on the core, 11 but if, for some reason, you are not able to put it on the 12 core, then put it in containment.
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| ('' 13 MR. WARD: Okay.
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| 14 DR. MARK: I turn it back to you, Mr. Chairman.
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| 15 MR. WARD: We are going to attempt to draft a 16 letter, I take it, tomorrow sometime?
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| 17 DR. MARR: I am willing to try to do that, 18 except, I don't know what it should say.
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| 19 MR. WARD: Well, you've got 15 hours!
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| 20 (Laughter.)
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| 21 DR. MARK: I think it will take about that long!
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| t 22 (Laughter.)
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| i 23 MR. WARD: Bob's offered to help you.
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| 24 ( r.aughte r. )
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| 25 DR. I; ERR: Mr. Chairman, I would like some ACE-FEDERAL REPORTERS, INC.
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| m1. , . s.m _ & c _ ,. mom
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| 071 15 12 195 L DAVbw 1 indication --
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| 2 DR. MARK: I hae an inclination to say that we 3 should encourage Mr. Bernero to keep going and go ahead, but 4 encourage the Commission not to jump on things, until they 5 have had a chance to see NUMARC.
| |
| 6 That would be my idea of what we might say. I am 7 not sure that it is acceptable. I wonder what the committee 8 would like to have it say.
| |
| 9 DR. KERR: I think it should say something like 10 that.
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| 11 MR. WARD: Okay.
| |
| s 12 I think we've got a sense.
| |
| 13 DR. OKRENT: He's got a sense of three opinions.
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| 14 I am not sure. I think he should try something.
| |
| I 15 MR. WARD: It is a matter of drafting a letter.
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| 16 DR. OKRENT: Once it's on the table, the 17 committee will agree or not. You know how they do.
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| 18 MR. WARD: Yes.
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| 19 j DR. MARK: I believe that is the best we can do, i
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| 20 Bob.
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| 21 l MR. WARD: Thank you very much.
| |
| i 22 ' Let's take a break for 10 minutes.
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| 23 l (Whereupon, at 3:50 p.m., the recorded portion of I
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| 24 the ACRS general meeting was concluded, and the committee
| |
| (~
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| 25 recessed, thereafter, to reconvene in unrecorded session.)
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| ACE-FEDERAL REPORTERS, INC.
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| m,m, , _ m- m.o -
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| | |
| n CERTIFICATE OF OFFICIAL REPORTER b)
| |
| N /
| |
| This is to certify that the attached proceedings before the UNITED STATES NUCLEAR REGULATORY COMMISSION in the l matter of: .
| |
| NAME OF PROCEEDING: ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 320TH GENERAL MEETING DOCKET NO.:
| |
| PLACE: WASilINGTON , D. C.
| |
| O DATE: rR1 DAY, DECEneeR 12, 198e were held as herein appears, and that this is the original transcript thereof for the file of the United States Nuclear Regulatory Commission.
| |
| (sigt) ,
| |
| (TYPED)
| |
| DAVID L. IlOFFMAN Official Reporter R reS Af l$ k n'
| |
| * O
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| | |
| -.e 1 - - _ _ m a + A 4, w - -.w.e ....---.e_ _ _ . - ,_ _ ,mm. . a.- a O
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| l l
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| 1 1
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| i POLICY STATEMENT i
| |
| ON O
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| DEFERRED PLANTS l
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| i i
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| i 4
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| i i
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| O tew--e-----*=, ew e y ----,e
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| | |
| I i
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| DEFINITIONS 4
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| DEFERRED PLANT
| |
| - CP IS IN EFFECT
| |
| - CONSTRUCTION CEASED OR REDUCED TO MAINTENANCE LEVEL
| |
| - LICENSEE HAS NOT ANN 0UNCED TERMINATION O
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| TERMINATED PLANT
| |
| - CP IS IN EFFECT
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| - LICENSEE HAS ANN 0UNCED THAT CONSTRUCTION HAS BEEN TERMINATED PERMANENTLY CANCELLED PLANT
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| - A PLANT WITHOUT A VALID CP O
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| | |
| =
| |
| l DIRECTIVES ON DEFERRED / CANCELLED PLANTS
| |
| * PORTIONS OF THE 1985 POLICY AND PLANNING GUIDANCE ITEM IV,B, PLANNING GUIDANCE 2 O
| |
| * REQUEST FOR PROCEDURES TO REACTIVATE A PROJECT AFTER CONSTRUCTION AND LICENSING HAVE STOPPED
| |
| * COMMISSIONER ZECH'S REQUEST
| |
| * SEVERE ACCIDENT AND STANDARDIZATION POLICY STATEMENTS O
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| | |
| , e i
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| I POLICY STATEMENT CONSIDERATIONS MAINTENANCE, PRESERVATION AND DOCUMENTATION REQUIREMENTS FOR DEFERRED PLANTS Q APPLICABILITY OF NEW REGULATORY STAFF POSITIONS FOR DEFERRED PLANTS BEING REACTIVATED PROCEDURES FOR REACTIVATING DEFERRED PLANTS IDENTIFICATION OF REGULATORY IMPROVEMENTS AND RESEARCH INITIATIVES POPULATION AND STATUS OF DEFERRED AND TERMINATED PLANTS a
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| : O.
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| i 4
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| _.n.~, ,.,,_,_-,,_,,_,_--,,.--,.,---.g., -
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| | |
| o o
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| SCOPE
| |
| * PROCEDURES DEVELOPED FOR DEFERRAL AND REACTIVATION OF DEFERRED PLANTS O
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| * DOES NOT COVER REACTIVATION OF CANCELLED PLANTS O
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| | |
| t ELEMENTS OF POLICY
| |
| * MAINTENANCE, PRESERVATION AND DOCUMENTATION REQUIREMENTS IDENTIFIED
| |
| - APPLICABLE REGULATIONS - 10 CFR PARTS-21, 50.55, 50.71, O
| |
| 50 APPENDICES AaB
| |
| - APPLICABLE GUIDES - R.G. 1.28, 1.37, 1.38, 1.58, 1.88 AND 1.116
| |
| - INSPECTION PROCEDURES AS APPROPRIATE O
| |
| | |
| 1 0
| |
| ELEMENTS OF POLICY (CONTINUED)
| |
| * APPLICABILITY OF NEW REGULATIONS DURING DEFERRAL g" - PLANT-SPECIFIC BACKFITS OF NEW STAFF POSITIONS WILL BE CONSIDERED IN ACCORDANCE WITH BACKFIT RULE -
| |
| 10 CFR PART 50.109
| |
| - GENERIC BACKFITS WILL BE IMPLEMENTED EITHER THROUGH RULEMAKING OR GENERIC ISSUE RESOLUTION
| |
| - PROVISIONS OF OTHER POLICY STATEMENTS APPLICABLE TO PLANTS UNDER CONSTRUCTION WILL BE IMPLEMENTED O
| |
| | |
| z
| |
| 'O PROPOSED REGULATORY IMPROVEMENTS
| |
| * REGULATORY CHANGES MAY BE NEEDED T0:
| |
| - ESTABLISH THAT CP REMAINS IN EFFECT (EVEN IF IT EXPIRES) UNTIL NRC WITHDRAWS CP
| |
| - CLARIFY LICENSEE OBLIGATIONS UPON PLANT TERMINATION O
| |
| * INTERNAL NRC GUIDANCE ON SPECIFIC INFORMATION NEEDED FOR TERMINATION OF CP
| |
| * DETAILED GUIDANCE FOR INSPECTION OF DEFERRED PLANTS PRIOR TO REACTIVATION O
| |
| 1
| |
| | |
| '% )
| |
| AIF PARTICIPATION
| |
| * STAFF MET WITH AIF, FEBRUARY 19, 1986
| |
| * AIF PROVIDED LETTER, MARCH 31, 1986 ON " REACTIVATION OF CONSTRUCTION PROJECTS"
| |
| - AGREES THAT POLICY STATEMENT IS NECESSARY
| |
| - POLICY SHOULD APPLY TO PLANTS WITH cps
| |
| (}}
| |
| - PLANTS WITH WITHDRAWN cps SHOULD BE HANDLED ON A CASE-BY-CASE BASIS
| |
| - 10 CFR PART 50.109, BACKFIT RULE, SHOULD BE USED TO IMPLEMENT NEW REQUIREMENTS IN EFFECT FOR PLANTS WITH cps
| |
| - CURRENT PRESERVATION REQUIREMENTS ADEQUATE AS LONG AS RECORDS MAINTAINED,
| |
| * REVIEW AND COMMENTS ON FINAL DRAFT, JULY 2, 1986 O
| |
| | |
| 4
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| .' i h !
| |
| . l i
| |
| j
| |
| : POLICY OVERVIEW i ,
| |
| l 3 ,
| |
| i i
| |
| i 3
| |
| i 1 - NO SAFETY IMPLICATIONS l i
| |
| i i
| |
| 1 lQ i
| |
| - ESSENTIALLY CONSOLIDATES EXISTING REQUIREMENTS i i
| |
| I i
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| 1
| |
| - C0ORDINATED WITH INDUSTRY f !
| |
| ?
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| e i
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| 4 l
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| f I
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| 1 5 I iO i
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| I t
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| 1
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| | |
| &J Lh f CHERNOBYL:
| |
| WHERE DO WE GO FROM HERE?
| |
| Proceedings of the Conference-by Computer Sponsored by McGraw llill's Nuclear Publications September 29 October 17 Where should the international nuclear community turn in the wake of the Chemobyl-4 trag What directions does Chernobyl illuminate for nuclear research, power reactor operations, and nuclear pir.nt regulation? What can we learn from the world's worst nuclearpower disaster about preventing accidents in the future?
| |
| To seek answers to the complex issues raised by Chernobyl, McGraw Hill's Nuclear Publications sponsored an international Conference by Computer for three we'eks from Septe 29 through October 17. Accessible by anyone with a personal computer and modem or other commumcations computer, and open 24 hours a day, the conference provided an international roundtable for members of the nuclear community the world over to interact and exchange ideas.
| |
| 'lte computer was open 24 hours a day so persons in all time zones could participate at their convenience, and more than 80 participants were registered in the conference.
| |
| The conference covered Chemobyl's impact in five major topic areas, and a distinguished list o experts contributed their thoughts to begin the international dialogue on each topic. The resulting proceedings may pose more questions than they provide answers, but they assuredly proside a thought-provoking portrait of the issues raised by Chernobyl.
| |
| ,Y
| |
| !s
| |
| | |
| ,, 4 l
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| 4 f*
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| s
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| ('v ; -
| |
| CHERNOBYL:
| |
| WHERE DO WE GO FROM HERE? .
| |
| Index to Proceedings Section I............................................................................................................. I.ist cl Conference Participan ts Section 1I.................................................................................S ummary of the Au gust 1986 IAEA Meeting on Chernobyl -- by Ann Maclachlan, Nucleonics Week S ection II1............................................ ......................... ...... ............................... Implications for Source Terms Se etion IV............................................................................................................. Implications for Containment s fS tJ Section V...........................................................................................Implications for Human Health Protection S ection VI................................................................. ........................... Implications for Accident Managemen t S e ction VII. ... ...... .. ................ .......... ....... .... . . . .............. .......... . ...... . . . ..... ..... ....... . .... .......... Fin ancial Implication s O
| |
| .c c r, c'
| |
| | |
| a ,
| |
| o CODE NAME CODE NAME .
| |
| cwalter - CHARLES WALTER ebatchelder ELEANOR BATCHELDER -
| |
| danderson DAVID ANDERSON chicken ENNO HICKEN -
| |
| Canason, Inc. GRS Vice President & Mgr. Ontario Operations 55 Queen Street, East,9th Floor ethrom EDWARD D.THROM Toronto, Canada MSC 1R5 U.S. Nuclear Regulatory Commission .
| |
| Phone: (416) 366 9421 Division of Safety Review and Oversight Telex #: 065 24582 Mail Stop 244 Washington, DC 20555 dbinak DAVE BIZZAK Delian Corporation , , fvanuitert FRED VAN UTIERT One Monroeville Center, Suite 700 Ministry of Economic Affairs Monroeville, PA 15146 Phone: (412) 856 5700 ghaywood GENE HAYWOOD N. Perry RKE dbunch DELBERT BUNCH Deputy Assistant Secretary for ghuston GAYLE HUSTON Reactor Deployment Cleveland Electric Hluminating Co.
| |
| Office of Nuclear Energy Washington, D.C. 20545 gmalcotsis GEROGE MALCOTSIS Name: DR. G. Malcotsis dmccioud DENNIS MCCLOUD Address: Motor Columbus, Ing..
| |
| Tennessee Valley Authority Unternehmung AG Parkstr. 27 dont C.D. (DON) FLL'TCHER CH 5400 Baden E.G. & G. Idaho inc.
| |
| Idaho National Engineering 1.aboratory Job
| |
| | |
| ==Title:==
| |
| Switzerland Vice-President g
| |
| P.O. Box 1625, Idaho Falls, Idaho 83415 gmhuston GAYLE HUSTON U.S.A. ,
| |
| CEI dpascur DON PASEUR ha!brecht HELhRJT ALBRECiff Tennessee Valley Authority Institut fuer Radiochemie Kemforschungszentrurn Karlsruhe dmse DAVE ROSE Postfach 3640 Argonne National Laboratory D 7500 Karlsruhe FRG dsamek DON SAMEK hdeckers HANS DECKERS Donaldson, Lufkin & Jenrette Studiecentrum voor Kemenergie dtorgerson DAVID'lVRGERSON help MICHAEL HOLMSTROM Atomic Energy of Canada Ltd. ASDFASDF dwenderoth DICK WENDEROTII hglocckner HANS GLOECKNER Name: Richard G. Wenderoth (Dick) Hochtemperaturreaktorbau-GMBH Employer: Florida Power & Light Gottlieb Daimlerstr.8 (FP&L) D-6800 Mannheim Germany Address: 700 Universe Blvd. Phone:(Germany W) (0) 621451242 P. O. Box 14000 Juno Beach, Florida hlefebvre HAZEL LEFEBVRE 33408 Belgonucleaire Department: Nuclear Licensing Interests: Spons & Tmvel hutch MICHAEL IRTTCHERSON Telephone: 305-694 3595 o .
| |
| Page12 CllERNOBYL CONTERENCE by COMPtTITR - Sept. 29. Oct.17,1946
| |
| | |
| v
| |
| , e, LIST OF PARTICIPANTS 3 CODE NAME (O abrachet ALAIN BRACHET CODE NAME -
| |
| bgamer BARRY GARNER Direction des Etudes et Recherches Nuclear Plant Engineering Department Electricite De France Pennsylvania Power & Light Co.
| |
| 6 Quai Watier. 1002 Hamilton St.
| |
| 78041 CHATOU Allentown, PA 18101 CEDEX BP 49, France Phone: (1)30 7176 94 bgelbe BOBO GELBE GWDG ajm ARTHUR MOORE Senior Licensing Engineer bkuczera BERNHARD KUCZERA Washington Public Power Supply System Nuclear Safety Projekt P.O. Box 1223 Kemforschungszentrum Karlsruhe Elma, Washir'gton 98541 Postfxh 3640 7500 Karlsruhe alhomme ALAIN L HOMME CEA IPSN France bmann BRIAN MANN Nuclear Operations Department amact ANN MACLACHLAN Virginia Power European Editor, Nuclear Publications P.O. Box 26666 McGraw HillInc. Richmond, VA 23261 128, rue du Faubourg St. Honore 75008 Paris, France bruegger BERTRAND RUEGGER OECD NUCLEAR ENERGY AGENCY ani LARRY A. CROSS (NEA),
| |
| O Computer Operations Manager, 38 Boulevard Suchet U Nuclear Engineering Department F75016 Paris, France American Nuclear Insun:rs Phone: 45 24 % 86 270 Farmington Avenue Telex #: 630 668 AENEA F Farmington, CT 06032 Fax #:45 24 % 24 Phone: (203) 677 7715 callen CARDIS ALLEN aprichard ANDREW PRICHARD U.S. NRC aseltz ANN SELTZ cholmstroem CONNY HOLMS1ROEM Technical support for conferencing. Studsvik energiteknik AB McGraw Hill,Inc. S-61182 NYKOEPING 1221 Avenue of the Americas Sweden New York,NY 10020 Phone:intW15521923 Phone: 212 512-6898.
| |
| clear JOHN WALMSLEY asharon DR. ARIEL SHARON Fauske & Associates,Inc. clove CAROL LOVE 16WO70 West 83rd Street Licensing Specialist Burr Ridge,IL 60521 Carolina Power & Light Co.
| |
| OHS 5, P.O. Box 1551 bcushman BOB CUSHMAN Raleigh, NC 27606 Niagara Mohawk Power Corp.
| |
| 300 Eric Blvd. W. cthomasjr. CHARLES THOMAS JR.
| |
| Syracuse, NY 13202 Yankee Atomic Electric Co.
| |
| 1671 Worcester Road bdavis BILL DAVIS Framingham, MA 01701 PNL Phone: (617) 872 8100 ext.2645
| |
| ;N CHERNOBYL CONFERENCE.BY.COMPtfrER -Sept. 29 , Oct.17,1986 PageI.I i x
| |
| | |
| v o i CODE NAME CODE NAME - .
| |
| ksoda KUNIHISA SODA mdps MLAFUMA DPS -
| |
| 3 Japan Atomic Energy Research Insumte Tokaimura Ibarakiken, Japan CEA W
| |
| mgoldman MORTON GOLDMAN kswinth KEN SWNITI NUS Corp.
| |
| PNL Sr. VP & Techmcal Director 910 Clopper Rd, Gaithersburg, MD 20878 kwoodard KEITH WOODARD 301 258-1735 Pickard, Lowe, and Garrick mholmstrom MICHAEL HOLMSTROM 11each LARRY LEACH NY Teknik Stockholm-Sweden UNC Nuclear Industries
| |
| * P.O. Box 490 mhutcherson MICHAEL HUTCHERSON Richland, WA Fauske and Associates USA 509- 783-9989 (Home) mkarasulu MUZAFFER KARASULU 509- 376-5362 (Work) NYPA We run N Reactor. . Nuclear Generation Department Graphite moderated. White Plains,NY 10601 Pressure tube.
| |
| Phone (914)6816842.
| |
| 4000 Mwt Pressurized water. mminns MICHAEL MINNS Negative void coefficient. CEI Diverse fast (1.5s) Scram.
| |
| Confinement. mnh MICHAEL HUTCHERSON Fauske and Associates lois LOIS WEBSTER American Nuclear Society mpastor MARIE HELENE PASTOR g
| |
| Atomic Energy of Canada, Limited 1pl LAWRENCE LEACH UNC mpreat MICHEL PREAT TRACIEBEL trobertson LARRY ROBERTSON FEMA mryan MARGARET RYAN Emgergency Management Specialist Chief Editor, Nucleonics Week 467 J. W. McCormack POCH
| |
| : Boston,MA 02109, USA msuomela MA*ITI SUOMELA Telepphone:(617) 223 9565 STUK Finnish Center for Radiation and Nuclear twebster LOIS WEBSTER Safety American Nuclear Society P.O. Box 268 SF-00101 Helsinki malexich MILT ALEXICH Fm' land American Electric Power Co.
| |
| npelzer NORBERT PFL'ZFR martyplys MARTY PLYS Inst. f. Voelkerrecht Fauske & Associates 16WO70 West 83 rd St. ogremm OTTO GREMM
| |
| ~ Burr Ridge D. 60521 USA KWU mberman DR. MARSHALL BERMAN oparis OSCAR PARIS Sandia National laboratories NRC i
| |
| Albuquerque, New Mexico, USA 505-844 1545 Technical Administrative Judge (Environmental Scientist) h l Atomic Safety & licensing Board Panel l mehiron MAURICE CHIRON U.S. Nuclear Regulatory Commission
| |
| , USSI Washington, D.C. 20555 UO PageI4 CHERNOBYL CONFIRENCE by COMPiliTR - Sept. 29 Od.17,1986
| |
| | |
| ... 3 CODE NAME CODE NAME unpputa IVO1RIPPtm jmaciellan JAY A.MACLELLAN -
| |
| G ENEL Baselle PactSc Nonhwest I.aboratories O P.O. Box 999 -
| |
| jbmarun JERRY MARTIN PN. Washington 99352 Banelle 509-375 2626 Ratnpile is a primary Contractor to the jcharles JEAN CHARLES IM...est of Energy at the Hanford Site Framatome in Washmgton State. Banele is also a conanctor to the U.S. Nuclear Regulatory jdevine JACK DEVINE/W. MICHAELS Commission for Emergency Nr iedr.ess J. DeVine is an Electric Power Research at commercial power reactors in the U.S. I Institute staff member and panicipated am involved in EP evaluanons at power heavily in the TMI post accident cleanup plants and standards development and programs. Jack is a conference paper performance testing of radiobionssay author. W. Michaels is frorn S. Levy Inc. laboratories.
| |
| in Campbell, Calif. Wayne is a senior engmeering consultant and is helping Jack jm * =k JOHN MATUSZEK monitor the conference forEPRI. Mr NYS Health Michaels' background is pnmarily nuclear John M. Manmele fuel performance and he is currently the Wadsworth Center for I.aboratories and data base administrator for numerous Research computerized research data bases, including NYS Department of Health several for EPRI and DOE on Chemobyl. Albany,New York 12201 Mr Michaels' experience with computers and nuclear power was also inntirM ori ytcW JM PRITN analysis of the TMI accident. Wayne can CEGB
| |
| ~
| |
| be reached by mail for JDEVINE or at SLI (408) 377-4870. jrausa JULIE RAUSA
| |
| , Baltimore Gas and Electric jgaunt JOHN GAUNT Principal Consultant Intemational Energy Wwough JACKSCARBOROUGH l
| |
| l Associates Limited, Washington D.C. MAC
| |
| ! Previously Senior Representative U.K.A.E.A in the U.S.A. Counsellor, jtrotter JOHN TROTIER
| |
| , Nuclear Energy, British Embassy, NUS Corp.
| |
| Washington D.C.
| |
| Tel. (202)-342-6728 until October 3 then jwalmsley JOHN WALMSLEY (703)-246 0444 ESCOM
| |
| , McGraw Hill jgleave JUDY GLEAVE kkish KARL KISH CEGB Centerior jguy JUDY GUY
| |
| * NN CEGB UCS Union of Concerned Scientists 1616 P St. NW jhastberg:t JIM HASSBERGER Washington DC 20036 LLNL kodonnell KEVIN O'DONNELL
| |
| [ Sardi J. JARDI kshea KAT1E SHEA Sim JULES JIM Newman & Holtzinger
| |
| ; _ . _ . _ . . . . ..ss .., e t
| |
| | |
| ~-
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| CODE NAME CODE NAME pellison PHILLIP ELLISON rhobbins RICHARD HOBBINS -
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| Fauske & Associates EG&G IDAHO pjones PE'IER JONES rllovet RICARDO LLbVET CEGB WNESP pharahalios PARIS KARAHALIOS rwight ROY WIGHT Stone & Webster Engmeenng Corporauon Ill. Department Nuclear Safety 245 Summer Street I Boston, Mass. 02107 saicalbert THOMAS ALBERT Tel. (617) 5891373 SAIC pparshley PAUL PARSHLEY ,~ shall STEVEN HALL Donaldson, Lufkin & Jenreue SRD/UKAEA 140 Broadway New York, N.Y.10005 ssholly STEVE SHOLLY MHB Techmcal Associates ppirila PEKKA PIRILA 1723 Hamilton Avenue VTT Finland Suite K Technical Research Centre of Finland SanJose,Califomia 95125 Nuclear Engmeenng Laboratory P.O. Box 169 sstiefel SILKE STIEFEL 00181 HELSINKI Institut fuer Reaktobauelemente Finland Kemforschungszentrum Karlsruhe Postfach 3640 pschmitz PAUL SCHMITZ D-7500 Karlsruhe FRG Bechtel Westem Power Corporation, Norwalk Califomia, tboulette TOM BOULETTE J (213) 807-3809 Mame Yankee psviatoslavsky PETER SVIATOSLAVSKY tmoore TAYLOR MOORE Wisconsin Public Service Corp. Electric Power Research Institute Owner / Operator of Kewaunee Nuclear Plant Senior Feature Writer,EPRI Joumal 600 n. Adams St. 3412 Hillview Avenue, P.O. Box IGtl2 P.O. Box 19002 Palo Alto,CA 94303 USA Green Bay WI. 54307-9002 Tel. (415) 855-2267 pthome PAUL THOME vhuguette VERSELE HUGUETIE Field Automation Institut Hygiene Epidemiologie ravery ROBERT AVERY wgraves WILLIAM GRAVES E.L du Pont de Nemours reopp ROBERT COPP Savannah River Laboratory INEL Aiken, SC 29808.
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| Robert D. Copp Manager, DOE Advanced Reactor wrossbach WERNER ROSSBACH Severe AccidentProgram Interatom GmbH EG&G Idaho,Inc.
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| PO Box 1625 xjardi XAVIER JARDI Idaho Falls, Idaho, USA 83415 Empresarios Agrupados rfeneny RETTA FENERTY zrevesz ZSOLT REVESZ LP&L Electrowatt Engineering Services, Ltd.
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| (.A CHERNOBYL CONFIRENCE.BY.COMPLTER - Sept. 29 . Oct.17,1986 Page15
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| l graphite moderator-which stores large amounts of thermal energy-included the lack of strong emergency l shutdown measures, such as a fast shutdown system. For example, the control rods would take some 20 l
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| seconds to drop fully into the core. He Soviet repon repeatedly emphasizes that because ofits higir capacity (1,000 MW), the RBMK is used for baseload power operation and should only be shut down when g
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| absolutely rwmry. Other sources say that it takes three to four weeks to get a RBMK-1000 back up to
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| , full power following shutdown. Dus, control systems are arranged in steps according to the severity of reactor disorders, with provisions for power reduction to 60%,50%, and 25% before the uhinnate descent to l full shutdown.De concentration of RBMK stations in the heavily populated western USSR suggests thar l their continued operation was basic to the region's functioning.
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| Bryan Edmonson of the Central Electricity Generating Board, who cha2 red the working group on the accident sequence leading up to core disruption, said the accident suggested two points for funher attention.
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| First is the importance of placing complete responsibility for safe operation in the hands of a senior officer on site and in the context of a "nuc! car safety culture" that envelopes all operations-tlus is what he called "the principal lesson from the Chernobyl tragedy." Second, the accident underlines the importance of train-ing, education, and development of operator aids. "Ihe (Chernobyl) control room staff were swamped with information," Edmonson said. The Russians have emphasized their desire to upgrade their simulater
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| '. programs to better model accident situations. (An RBILDC simulator at Smolensk apparently is used chiefly, if not exclusively, to simulate normal operations.)
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| Some western experts observed that the Soviets " appear to have done nothing since Bree Mile Island" l in the ama of men = machine inte, face, at least on RBMKs,in contrast to the wholescale makeovers of con-l trol rooms and other sumlar initiatives that have been taken in the West. Several of the westem experts said
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| ! . they were ready to share expenence with the Russians in that field and to help design simulator programs if asked. French representatives confessed to be somewhat puzzled at the Russians' sudden discovery of the importance of man-machine interface, since through bilateral contacts they should have been quite aware of what France and other countries were doing in that domain.
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| , How did the accident actually happen?
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| Stated simply, the accident sequence was as follows. The turbine-generator rundown test was supposed g to be done at between 700 MW(t) and 1,000 MW(t), but was delayed for several hours because the grid W needed extra power from Chernobyl-4. In the meantime, the operators had decided to disconnect the emer.
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| gency core cooling system (ECCS) pumps so that the test conditions would best approximate emergency conditions. By 1:00 a.m. April 26, all control and safety rods had been with drawn from the core so that
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| - power could be ratsed to the 700 MW(t) level required for the test, compensating for the xenon poisoning that had built up over nine hours of unscheduled operation at low power the evening before and an operator error-failing to properly synchronize the local automatic control rod system and the global automatic con-
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| : trol rod system as the second took over from the first at low power-which had allowed the reactor to drop to only 30 MW(t) around midnight. De operator could get the power up to only about 200 MW(t).
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| He ECCS had been switched off since 2 p.m. the previous day, although operation without it violated l "a most sacred rule." All eight main coolant pumps were operating at regimes far higher than normal al-though the reactor was at only 200 MW(t)(veYsus design capacity of 3,200 MW(t), increasing coolant flow l
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| through the core to several times normal levels. Steam pressure and water level in the steam drum separators began to drop as the coolant was saturated, and the operators disconnected further trip signals as-sociated widi those parameters so the reactor would not trip before the test could be performed. Re automatic control system pulled rods up with the drop in steam volume.
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| The experiment proper began at 1:23:04, when the staff closed the emergency regulating valves on the second turbine generator (No. 8). When the pumps began to run down with the TG, flow was
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| ' reduced, the coolant boiled and the reactor power began to rise slowly. Two attempts, at 1:23:40 and a few seconds later, to activate the sermn system (which in fact took 6 seconds to " bite" at all) were in vain.
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| Legasov said that even the reason for pushing the AZ-5 (emergency protection level 5) scram button was
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| ~ ambiguous, according to accounts given by the operators "while they were still alive." Perhaps,' they said, it was not because the shift supervisor saw the power rising at all, but because "he was sure the tests were going all right" and thus the rextor could safely be stopped.
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| In any case, at that point,"the reactor was free to do what it wished," according to A.K. Kalugin., of the g Kurchatov Atomic Energy Institute. What it did, in fact, was to go prompt critical, reaching 1.5 beta (per- W centage of prompt neutrons) in less than two seconds. Its power shot up more than 100 times the initial 200
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| . MW(t) in less than a second to reach some 300 calories per gram of fuel, at which point, it is postulated, the
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| , ,
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| * fuel disintegrated-in effect, exploded. In this respect, the accident can be said to have been detonated by ug ,. the explosion of the reactor's overheated nuclear fuel But the participants in Vienna agreed that the
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| , , Page H 2 CHERNOBYLCONFERENCE.BY.COMPLTER-Sept.29 Oct.17,1986
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| . ~
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| PROLOGUE This article, which appeared in the Sapr. 4 issue ofNucleonics Week, portrays the state ofknowledge about Chernobyl aper the specialInternational Atomic Energy Agency menring in Wnna Augua 23 - 29,1986. ~
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| Q WHATTHE EXPERTS LEARNED FROM CHERNOBYL POST-ACCIDENT REVIEW The Chernobylpost accident review meeting in Vienna was dividedintofour working groups on thefollowing topics: the accident sequence leading up to core duruption, the sequence post-core disruption. decontammation and evacuation eforts, and medical and biological aspects. Thefollowing report by Nucleonics Week's Ann hiac-Lachlan presents digests ofinformation disclosed about each topic, culledfrom chairmen's summaries, press con.
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| ferences, and individual intervsews, as well as daily summary reports preparedfor the UX. government by John Gittus, head of the S4ety andReliability Directorate of the UX. Atomic Energy Authority.
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| Why did the accident at Chernobyl happen at all?
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| l The Soviets have, with considerable justiacation, pinned the cause of the accident on an incredible con- l fluence of" deliberate and willful" violations of operating rules and procedures by the unit's operators. However, Valery Legasov, leader of the Soviet techmcal team and himself untainted by association with the RBMK reactor type (Legasov is a physical chemist interested in high-temperature and molten salt reactors), told the Vienna meeting that the mistakes had begun with the RBMK designers themselves. Although the drawbacks of the RBMK design were " evident from the beginning," the designers made "a tremendous psychological mis-take"in not foreseeing the possibility of such gross operator errors.
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| Moreover, when the RBMK was designed 25 years ago, automated control technology was considered less reliable than operators, and the units have evidently not been backfitted with more modern control systems.
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| "Ihis is our claim agamst the designers: now, with hmdsight we can see that (the accident) could have easily been prevented using technical means (i.e., engmeered safety features),"I.egasov said. Dismissal of the chief designer of the RBMK, Ivan Emilyanov, was announced by the Soviet Politburo in July (NW,24 July,3).
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| The immediate genesis of the accident is by now well known. Station management of Chernobyl-inciden-tally, the best running RBMK station up to the accident-had contracted with the firm responsible for the unit's electrical system, Dom Tech Energo, for tests of tubine-generator rundown. Dey wanted to see how long the feedwater putnps could be powered from the still-spinning generator rotor in the event of a loss cf offsite power O and before the unit's own backup diesels could be switched in, his would have needed to be about 30-40 seconds, as the backup diesels apparently are not the fast-startmg kind, possibly for economic reasons.
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| Legasov said although there had been ''a lot of discussion in the Soviet Union on the justification for this test in general," the turbine-generator rundown calculations had been incorporated in the RBMK de and presumably in the safety analysis reports as well. During initial tests of the rundown regime in 1982 and 1984, it was found that the voltage on the generator busbar had dropped off long before the rotor's mechanical energy was ewh==='ad The Chernobyl 4 team was to test a new impulse block designed to keep the voltage up for the required period of time. Whether this was ordered by safety authorities in Moscow or was an initiative taken by the station itself was not clear and, in fact, a specific question to that effect was not answered by the Soviets.
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| De latter hypothesis would seem to be strengthened by Legasov's remark that the experiment had not been properly designed nor properly cleared with authorities. It was, in fact, not even regarded as safety-signiScant by the station management. One of the points still unclear after the Vienna meeting is the underlying motivation for the vus' kamikaze behavior: up to the very last minute, they drove to complete the turbine-generator test, even when the reactor was dangerously unstable and when they had disconnected all safety and protection systems. Much has been made of the operators' apparent ignorance of the dangers of what had been a smoothl running power plant. But Soviet scientists, led by A. Abagyan from the Institute of Nuclear Power Plants (described by Abagyan as the Soviet equivalent of the U.S. Institute of Nuclear Power Operations), also em-phasized that the accident occurred at a very bad time psychologically. It was at the end of the work week and early in the moming. It is also worth noting, as Gitrus does in his report, that it was the right before the May I national holiday. De operators knew that if they did not complete the test that night,it would have to await the next shutdown the following year.
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| He operators were so determined to complete the test that late in the pre accident sequence, they attempted to throttle the reactor back up to 20% power-rather than letting it run down as the experiment program called for-so the test could be repeated in case it failed the first time. A French expert said that on the Electricite de O France system-based on a standardized reactor series as in the USSR-if such a test could not be done at one unit, it would simply be tmnsferred to another. But perhaps the Chernobyl operators were aiming for some kind of award or distinction to be noted in the station's annual report or for personal recognition for completing the test.
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| Design features that contributed to the accident, besides the positive void coefficient and use of CHERNOBYL CONFERENCE.BY.COMPIttT.R - Sept. 29 - Oct.17,19s6 Page II.1 Q'
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| f
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| limited quantity in the steam separators.
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| Taking into account the possibility of a core meltdown following the explosion, the Soviets developed a special refractory concrete found eff.cient up to 2000 degrees C for use as a core underpinning, but ir proved unnecessary. About 25% of total graphite, or about 250 metric tons, was estimated to have been g
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| consumed in the graphite fire. The rest of the graphite blocks are probably in the outer space surrounding the reactor.
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| V.F. Demin of Kurchatov, repeated the earlier Soviet estimate of 50-million curies for noble gases and 50-million curies of other radionuclides, with a 50% error margm.nese numbers are based on measurements taken on May 6. Westem scientists say this corroborates with their estimates, made in May on the basis of fallout over western and northern Europe, that 20% or more of the core radionuclide inven-tory was released. One expert estimates that 20% of the cesium inventory and 40% of the iodine may have been released, including dropping of 12-million curies of radionuclides corresponding to the composition of fragmented fuel on the first day (April 26) in the "near-in zone" assumed to be in the 30-km radius around the power plant.
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| Emergency measures taken following accident.
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| De Soviet experts also outlined the immediate firefighting efforts, with three units deployed to the ac-
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| . cident within a matter of minutes. nanks to their efforts, the fire was extinguished by 5 a.m., mainly using water. Priority was given to limiting the spread of the fire to the adjacent Unit 3, whose turbine building roof apparently had caught fire. They also described the well-publicized and unprecedented program to idrop a total of 5,000 metric tons of materials on top of the reactor from helicopters beginning April 27. First came 40 metric tons of baron carbide to stop any remaining chain reaction, then 800 metric tons of dolomite (limestone) to starve the graphite fire of oxygen. There followed 2,400 metric tons oflead for shielding and to carry excess core heat to the bottom of the debris, and finally sand and clay as filtering agents.
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| However, Legasov noted, this cover had the unsenling effect of increasmg the temperature of the core by reducing air flow, and after the dumping was stopped on May 2 because designers of the dropping i scheme feared the reactor vault would yield under the weight of the materials, releases began to rise steadily, reaching 8-million curies on May 5. It was at this point that the Soviets decided to pump liquid g
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| nitrogen into the reactor from underneath, and this, combined with natural convection of air, led to an even-tual drop in temperature and decrease in releases.
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| Legasov noted that taking measurements had not been easy, especially right following the accident. The high radiation fields-from tens to thousands of roentgens / hour-rendered semiconductor instrumerits from the U.S., Sweden, and the USSR unreliable for temperature measurements. "Ihe more complex the sys-tem," he said,"the less reliable the results in the given raantinn circumstances."He Russums used simple devices such as thermionic valve amplifiers and materials of known melting point.
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| l As for the " sarcophagus" planned to cover unit 4, the Russians have chosen an open circuit system over a closed circuit because it facilitates measurements. It is not clear how much of the planned entombment will be finished by this fall. One expert thought it would be the outer wall only, to protect workers coming
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| ! back to restart Chemobyl-1 and -2 and perhaps unit 3, with the rest of the sarcophagus work taking much longer.
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| i In his opening remarks, Legasov addressed the subject of the initial administrative response,in-cluding how evacuation decisions had been made. He confirmed that the plant management had promptly informed Moscow-western participants said it had been Abagyan himself-that a full- fledged emergency was underway "a few minutes after the fire began." Abagyan and his team left immediately for the plant a site. Unfortunately, Legasov continued, in subsequent communications the plant management "somewhat distorted" their original alarm," informing us that they could control the already inexistent reactor.They did j not adequately understand the situation." When Abagyan and his team arrived after a few hours, they im-mediately assessed the scale of the disaster, informed the government, and by 8 p.m. on April 26, a govemmental response committee had been set up and Legasov himself was on site.
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| He decision to evacuate the town of Pripyat, only a few kilometers away from the plant, was taken at 9 p.m. even though the first wave of releases had miraculously missed the town. But because of the way l radiation had spread around the plant, Legasov explained,"not a single one of our previously prepared g emergency plans could be implemented." He said he believed that if the evacuation had begun that night, w the loss in terms of human life would have been greater than it was (In fact, no members of the general population have died or suffered acute radiation sickness, according to the Soviets). In effect, the roads were more dangerous than stone houses. De evacuation was organized during the night-by which time g
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| * the radiation situation was " worsening" around Pripyat-potassium iodide pills had been distributed by I
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| . i l
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| .1 I
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| : destructive physical phenomenon was a steam explosion.
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| De small particles of fuel, at 3,000 degrees C, converted the remaming water droplets in the channel to O steam in a classic fuel-coolant interaction, which blew off the channel plug and displaced the roof slab.
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| Dis, in turn, ruptured pressure tubes in all 1,660 fuel channels, exposing them to the air in the reactor buddmg. His was accompanied by "various chemical and exothermic reactions" such as steam ztrconium l
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| l and steam-graphite,Legasov said.
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| l De Russians, in fact, do not have measurements for the actual accident sequence, since operators had l directed the plant's computer 1o record in priority those parameters linked to the TG test. What they pesen- -
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| led in Vienna is a mathematical model of what they think %=1 which they now plan to venfy Eth fur-ther expenments. A graph shown by Legasov on the first day showed a drst, small peak in reactor power, followed by a trough due to an initial reactivity dara,aaning Doppler effect, then an enormous surge at 1:23:45 as the power shot up off the chart.
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| Witnesses were quoted as saying they heard a second explosion three to four seconds after the Arst, at 1:23:48 according to the Soviet model, in what "seems to be close to a volumetric explosion" ac-cordmg to I4gasov. The Russians assume the second explosion came fmm detonataon of hydrogen or car-
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| * bon monoxide, although some destern experts think it could have been a reactivity excursion and fuel-coolant interaction in another fuel channel. In any case, for the Soviets, the nantre of the second explosion is "not their 8rst priority," accordmg to Pierre Tanguy of Electncite de France, the IAEA expert in charge of the accident description.
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| In his concluding remarks, Tanguy stressed that power excursions are "nothing new for safety analysis."
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| In fact, past power excursions have been on the order of 1 to 10 nulliseconds, whereas at Chernobyl the time constant appears to have been much slower, more like a second, although this still must be verified through further experiments. The time constant in a nuclear explosive device is in units of nanoseconds, no greater than one-billionth of a second, he recalled. What happened at Chernobyl"has nothmg to do with a nuclear bomb,"Tanguy said.
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| The French expert noted that "the last minutes of that explosion are very interesting for reactor physicists and thermohydraulic speciahsts." He expressed hope that there would be the opportunity for the
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| . ir.ternational community to use the Soviet data to validate computer models and their underlying as-a
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| .O e
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| sumptions, which could be applicable to reacter designs everywhere. Parametric studies,in which the acci-dent is simulated with parameters changed one by one, also could best answer the quesuon, raised several
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| , times last week, of whether the backfits and other measures announced by the Soviets to increase RBMK
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| ; safety are in fact sufficient. Such studies, he said, are i i ot understand reactivity accidents and to analyze the probability and consequences of severe accidents.
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| Tanguy quoted Kalugin as saying the explosion involved about 30% of channel volume, in the lower part of the core. Here was "some kind of homogenization and a corresponding increase in multiplication" (reactivity). Graphite blocks were ejected from the core. The first explosion was calculated to have generated " tens of atmospheres" of pressure, while the reactor roof slab was designed to resist only two at-mospheres. French specialists, workmg back from the energy needed to rupture all the fuel channels, have estimated the amount of energy released in the first explosion at 200 megawatts per second (200 megajoules).
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| ).
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| Tanguy said that what happened to the fuel loading machine is " immaterial" and had no beanng on the accident. Simdarly, the Soviets say that the spent fuel pool-es well as all piping and components con-tamed in the leaktight confinement compartments and onsite gas and fuel oil storage tanks-were un-damaged in the explosions. "Nothing happened to the spent fuel pool," Tanguy said the Soviets had told the
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| , delegates. De water was still in place, as were the approximately 100 spent fuel elements in storage at the time of the accident. (The Soviets reported that 75% of the Chernobyl-4 fuel in-core at that time was still
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| , first-load fuel).
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| The "first priority" for the Soviets,Tanguy said, is locating the dispersed fuel, so that plans can be carried out for entombment of the reactor. Abagyan reported provisional figures estimating that 3.5% to 1
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| 4% of the fuel (about seven metric tons) was released from the reactor, with 03% to 0.4% dispersed on site (in aerosol particles from one to several microns in diameter),1.5% in a 20-km zone around the site, and 2% "elsewhere." The Soviets confirmed that the uranium fuel had undergone oxidation during the accident and may have reacted with the graphite to form carbides. ney said they would make available a great deal
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| ; of data on this subject.
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| i Visual examination confirmed that only about 10% of the graphite had been ejected from the reactor building, and it did not contain fragmented fuel, ne Soviets have found no fuel in the turbine hall, Tanguy reported. They believe most of it remained in the bottom of the reactor well and adjacent piping, with a CHERNOBYLCONFERENCE-BY.COMPLTER-Sept.29 Oct.17,1986 Pase it 3 c.h f
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| r
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| ,,j tims of severe radiation. " Rey clearly had a well-drilled system," commented one western medical expert. I "It was very impressive." He said there might be a link with civil defense organi7atinn, but the most accep- l ted view is that the Soviets have previous experience with emergency treatment of radiation victimf '
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| Byin lumself said that in retrospect, he was astonished at the scale of the response and its quick or- ,
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| ganization: hundreds of Soviet institutes supplied specialists, millions of dosimetric measurements were taken, and several hundred thousand people were medically examined, including blood tests, by May 10. 1 In the initial response, two emergency surgical teams were on the way within minutes and four teams j within an hour. He first 29 victims of fire and radiation were admitted to regional hospitals by 2:10 a.m.,
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| barely a half hour after the accident began. Potassiurn iodide tablets were distributed to all site workers and j patients by 3 a.m. A special muld-disciplinary medical team was alerted in Moscow at 6:40 a.m. and was en
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| ! route for Kiev by 11 a.m. Iodide tablets were being distributed by medical staff and Komsomol teams by 8 p.m. ,
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| ( Activity in the accident plume reached dose rates of 1,000 millirem per hour on April 27 and 500 mrem / hour on April 28 at a height of 200 meters and a distance of 5 to 10 km from the reactor site. Dose
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| . rates of one mrem / hour were measured from aircraft at a height of 1100 meters about 30 km northwest of the site.
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| l In terms of composition, the first release was very similar to the fuelinventory of the unit but was enriched in volatile nuclides such as iodine and cesium. Further away from the site, volatile nuclides were i found to dominate completely. However, fuel particles at various distances were found to contain single l nuclides, a phenomenon " difficult to understand," according to Dan Beninson, of the Argentine Comision l Nacional de Energia Atomica's licensing branch and chairman of the International Commission on i Radiological Protection, who led the discussion on radiological aspects.
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| i ne initial release contained a large amount of beta-emitters and caused problems ofinhalation, leading )
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| l to severe radiatinn damage to mouth and nose, Guskova told the experts. Once the most severely irradiated l were given bone marrow transplants-all but three have died since, mostly from herpetic m ' fections-there l
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| was a second wave of major problems three weeks later due to the recurrence of beta radiation burns: "even decontamination wasn't enough to get (the radioactive dust) all off," a UK expert commented. As the per-l i sonnel had not been wearing high-dose film badges, the vicdms were divided into dose categories on the l
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| basis of what the UK specialist called "the vampire syndrome"-lymphocyte counts in massive blood samples drawn in the first 24 hours after admission.
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| h At the time of the accident, there were 176 operational staff on site as well as 268 construction site workers. Of 300 people checked for radiatinn sickness in the early days,203 were found to be suffering from it. Here were 22 victims in the Category IV (most severely irradiated) level who had received bet-ween 600 and 1,600 rads; all but one are dead. Of the 23 victims who received 400 to 600 rads, seven are now dead, while of the 158 victims who received between 100 and 400 rads, only one has died so far.
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| One of those working at the plant on the night of April 25-26 was not found later, it is assumed he was working on top of the reactor and was buried in the wreckage and/or irradiated to immediate death. Interest-ingly Abagyan of the Nuclear Power Plants Institute said that the three operators present in the control room the night of April 25 survived and are "in fine shape" at present, although they have been punished for " severe violations" of regulations (he did not know the nature of the punishment). He four or so people in the turbine hall at the time of the experiment-presumably employees of the electrical firm who were in-volved in the experiment-did not survive, he indicated.
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| l Dyin said the accident had emphasized the importance of skin dose in determining the prognosis of ac-l cident victims: 20% of the victims had lost 80% to 90% of their skin, mostly from beta radiation. However, Na-24 tests had proved that there was no neutron irradiatinn involved.
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| He UK speciahst said that the Russians had used " good standard medicine, simple hygiene, very basic broad. spectrum antibiotics-no high-tech" methods. It seemed to work, as in his opinion the medical .
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| team saved all those who were salvable. All those who received doses under 4 gray (400 rads) are alive today and on the way to recovery, he reparted.
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| l The Vienna participants spent a good deal of time discussing the problem of followup of the Chemobyl victims and the general population in the European part of the Soviet Union. Beninson said it was agreed that"all irradiated groups that can be studied should be studied." But as for non-stochastic effects in the general population, he noted that past studies had sometimes relied on elaborate registries that had not always l proved cost-beneficial. His was one of the most urgent areas for intemational cooperation, participants agreed.
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| "His is the experiment" on the biological effects of non-ionizing radiation, said one medical specialist. "In 20 to g
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| 30 years' time we're going to know whether the linear dose hypothesis" is correct,"at least for leukemia and maybe for lung cancer."
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| As for the estimates of long-term radiological consequences, the Soviets acknowledge that their models are C.'
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| CHERNOBYL CONFERENCE.BY.COMPtJTER -- Sept. 29. Oct.17,1986 Page II.6
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| volunteers at 8 p.m., and by 11 a.m. April 27, all was ready for the 45,000 inhabitants to be taken away in 1,100 buses.The town was totally evacuated in 21/2 hours, the Russians told the Vienna meeting.
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| Another 90,000 were evacuated in the next 10 days from the surroundmg areas including the town of Chemobyl 15 km away, so that altogether about 135,000 people were evacuated from a 30-km radius area.
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| - 3 U.K. expens esumate that groups of the 90,000 later evacuees-basically a rural population that spends much time outdoors--received external doses of 30 to 50 rads, and 10 times that to the thyroid from inhala-tion, assummg they had followed instructions not to drink milk from the area and to take iodme tablets.
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| 'Ibese doses would be twice as high as those to the Pripyat inhabitants evacuated April 27.
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| The Russians, indicated that their criteria require action when predicted whole-body doses exceed 75 !
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| rem. A"whole set of problems" arose at Chemobyl, including where to take the evacuees, how to decon.
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| ; tammate them and change their clothing, and what to do with the tens of thousands of cattle and other lives-lock. The ws iul evacuation eAphwe had shown, said East Germany's Harald Rabold, who led the discussions on decontamination work, that "only a strong centrahzation of authority" could make possible
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| =b= It was clear from the descriptions that the military played a key role in d.c evacuation such an s-l-and funher decontamination work.
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| At the plant, loose cesium contanunanon proved a predominant problem. Decontaminant sprays were used widely, with vacuum cleaners picking up loose particles. Some quick-drying films were applied to
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| . walls, which pick up active particles and can be then peeled off: solid wastes are being stored in the waste
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| .eyv=-y for Unit 5, which had aheady been completed.'Ihanks to the nanonal hydro- meteorology ser-vice, which constantly dusted the clouds, rain was pa=anad until the end of May, although this created problems on the ground as the radioactive dust resculed and whole areas had to be decontammated again.
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| The video shown by the Soviets in Vienna has a lot of footage on the decontaminauon effort as well as on the emergency headquarters directing the apeiaa.The decontaminanon team involved about 1,000 peopic in protective clothing, with all sons of equipment including concrete mixers.
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| Legasov gave a report August 25 on the state of the reactor and plant four months after the acci-
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| ! dent. Accordmg to legasov, the release of activity from the reactor vault has ceased, with only aerosols es-caping at the rate of some tenths of curies per day; temperatures above 200 to 300 degrees C have not been found at any point; and air and water terng.s-. do not exceed 45 degrees C and are stable. A diagnostic
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| ; system based on buoys lowered into the reactor allow determination of the radiation levels and isotopic !
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| ; content of releases.
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| I.egasov noted that "one of our priority tasks was to shut down units 1,2, and 3." It was not fully ex- .
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| plamed why the third unit,just next to the damaged one, was not shut down until 5 p.m. April 26, and the first and second units not for 24 hours. Western =p~elim suggested that power from these units was cru-cial to the evacuation and fire-6ghting effons. Now, Legaso'v said, it has been determmed that units 1 and 2 equipment is totally in working order, so the interior of those buildmgs is being decontaminated with a view to restarung the units by the end of this year. He did not explain how the operation would be or-ganized, although he acknowledged that the " main problem" in restart is finding a new area to house the staff. "Ihe town of Pripyat is not inhabitable for the foreseeable future," he said. Review of unit 3 is now underway, and when it is completed,"we will draw a conclusion" on restart of that unit,I.egasov said.
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| i l 'Ihe losses from the accident in the European part of the Soviet Union comprise 203 seriously injured.
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| l 31 dead (all these from the plant staff and the fire-fighting teams), collective doses of 9-million manrem to a population of 75-million in 1986 and 29-million manrem over their lifetime. 'Ihe population in the evacuanon zone (135,000) is estimated to receive 1.6-million manrem in 1986. 'Ihe figures on ir.temal dose, largely tivough cesium- 137, are based on planning levels rather than realistic ones and are believed i by non-Soviet experts to be too high by a factor of 10.
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| In the future, the area around the power plant will be divided into three economic zones according to level of contamination, Legasov said. First is a " complete isolation" zone, where no work (except presumably operation of the other Chernobyl units) can be resumed in the near future. Second is the evacuation zone (assumed to be in a radius from three km to 30 km from the plant) where, once it is decon-tammated, pernal economic and industrial activity can be resumed, with livestock remaining a question i mark.The third is a " monitoring zone," which is assumed to pose no danger for human health but is g maintamed under constant surveillance because of the possibility of wind direction changes. ,
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| What have been and will be the accident's radiological effects?
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| Participants in the Vienna meering were unanimous in their admiration for the Soviet emergency medi-cal response to Chemobyl, which was outlined in great detail by I.conid Ilyin, director of the Institute of Biophysics and chairman of the USSR National Radiological Protection Board and by Dr. A.K. Guskova, also of the Institute of Biophysics and director of Hospital No. 6 in Moscow known for its treatment of vic-Cs CHERNOBYL CONFERENCE-BY-COMPtfrER - Sept. 29 . Oct.17,1986 Pase II.5 i
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| L--.. - ,. -- - ..-. - --- . - . . - - - - -. - - - - - - - - . - . - -
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| described above. . trar+ust for the public in order to regain acceptability The fuel dispersion was reported to involve 3.5-4%. - of nuclear power after the Chemobyl accident.
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| of the fuelinventory,i.e. about 7 metric tons. The -
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| ulting small fuel panicles contained fission products transuranium elements with concentrations = i corresponding to the fuel bum up. It is quite clear, source terms /mtro #2, from sysop,5235 chars, Fri Sep therefore, that roughly the same percentage (3-4%) of all 26 14:41:13 1986 low volatile elements (Mo, Ba, Sr, Ru, Zr, Ce, Np, Pu, Cm, ) has been released. Since the percentage Trn.E: Paper 2 ccxispcmds very well to the amount of dispersed fuel it Chemobyl and LWR /PHWR Source Terms can be concluded that fuel dispersion was the principal release mecharusm for all low volatile elements. David F.Torgerson In addition, the dispersed fuel particles may have a Atomic Energy of Canada Research Company served as effective carriers for highly volatile fission Pinawa, Manitoba, Canada ROE ILO products like I, Cs, and Te which were released by vaporuation from less heavily damaged pans of the core When discussing the relevance of Chemobyl to and subsequently condensed on these particles. ( he LWR /PHWR source term technology, it is necessary to integral surface of the aerosol panicles is considerably enunciate clearly the essential differences between the larger than the surface of all solid structures in the reactor Chemobyl and LWR /PHWR accidents. For convenience, hall.) the Chemobyl source term can be divided into three parts:
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| : 1) the initial explosive release,2) releases occurring during core coveriag, including those occurrmg during
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| : 4. CONCLUSIONS graphite combu: tion, and 3) releases occumng after the core was coverx!.
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| Since a transient overpower accident caused by prompt criticality can be excluded for westem LWRs, the Explosive Release most severe accident to be considered here is a coremelt Ecident (CMA). However, initiating events as well as The explosive release was charactenzed by the direct scquences and source terms of coremelt accidents are very expulsion of radioxtivity to the environment. I believe
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| 'ferent from the Chemobyl accident. that such a release is unlikely in LWR /PHWRs for the A CMA is expected to occur after a loss of coolant following reasons. While all reactors have scenarios accident, if all emergency core cooling systems would fail whereby positive reactivity can be inserted into the core, and the fuel would melt due to missing removal of the Westem reactors have powerful emergency shut-off radioactive decay heat. The main characteristics of this systems that are designed to prevent prompt criticality type of accident have been investigated during the past 12 accidents that are characteristic of a panicular reactor type.
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| years, and source terms for a variety of accident sequences, Also, the presence of large, strong containment buildings especially for PWRs, have been evaluated. In these cases, would attenuate any releases. Even if the containment the main release mechanism will be vaponzation from the building were impaired by the accident, our current liquid coremelt at temperatures in the range of 2200- 2500 understanding of aerosol physics and chemistry suggests C. The low volatile fission products and transuraniu n that there would still be considerable attenuation of the elements will contribute very little to the integral source releases, depending on the nature of containment failure.
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| term while the main radiological risk will arise from the released nuclides of the elements I,Cs, Te, and Sb. In the Releases During Core Covering and Graphite case of an intact reactor building, the radiological source Combustion term will result only from leakages containing Kr. Xe, -
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| gaseous iodine, and very small amounts of aerosol The exposure of the Chemobyl core to the atmosphere particles - with the consequence that no long term also had a large effect on the releases. First, at'least pan of contamination of the environment will occur. the core must have been exposed to hot, oxidizing In our opinion, future efforts on source term related condidons. (In fact, conditions in the core may have been questions should include the following aspects: both oxidizing and reducing depending on airflow and on graphite chemistry.) These conditions may have resulted
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| - Completion and refinement of source term analyses in the oxidation of UO2, which would break up the fuel for coremelt accidents, in panicular, further investigations matrix and, thus, would expose fission products to the on the formation of molecular and organic iodine, on the environment. In addition, graphite can react with UO2 at spon behavior of fission products in BWRs after temperatures greater than 1500RC which would also affect from the fuel, on leakage rates of aerosols and the fuel matrix. Finally, the bummg of the graphite ases from reactor buildings . produced a high density of aerosol panicles that adsorbed l
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| radioactivity, and that were transponed to the environment
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| - Intensified attempts to make the results of risk studies by the thennal plume. Such releases are unlikely for Page III 2 ,
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| CHERNOBYL COhTERENCE.BY.COMPLTER - Sept. 29 . Oct.17, t986 tS'd,
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| still insufficient, especially to predict internal doses through the food chain. De spedal quality cf the Ukrainian soil, which is rather low in clay and humus content, may cause an uptake into the soil of cesium-134 and -137 in the area around Chemobyl several times what one would expect in western Et ropean soil,'according to Soviet calculations based on data and models developed to study weapons fallout. .
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| Some 1,000 whole. body examinadons performed so far of exposed people have shosm agreement between h
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| observed and calculated cesium levels in only about 3% of cases, while the remaining 97% average about 10 dmes lower than expected. His would indicate that the expected dose of 210- million manrem to the larger populadon from internal contamination over the next 70 years, which the Russians say is a " maximizing" calcula-tion used for planning purposes,is too high by a factor of at least 10, as Beninson himself pointed out at the con-ference.This, in turn, would lower the Soviet esdmate of cancer fatalities in the Soviet Unior4 from Chernobyl by an order of magitude, from some 25,000 to several thousand.
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| Although the point was not stressed much during last week's meedng, the Soviet report revealed that en-vironmental damage was expected in the immediate vicinity of the power plant. Notably, hydrobionts (water plants) in the cooling ' pond had received intemal doses of up to 10 rad /hr. Studies of the effects of the accident on living organisms and ecosystems are condnuing, the Soviets said.- ,4nn Maclachlan, Vienna CCopyright 1&J6 by McGraw-HiD,Inc.
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| L.
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| O
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| \q '"
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| CHERNOBYL COSTERENCE.BY.COMPLTER - Sept. 29 . Oct.17,1955 Page H.7
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| . . - = - _ = . . . - -
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| - . Topic One: September 29 - October 1:
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| O ras souncs rtan iurticirious I
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| 4 aerosol and gas release was L. yurted into high source terms /mtro #1, from sysop, 7105 chars, Fri Sep 26 14:39:58 1986 = y44; regions (1500 m and even higher). The There is/are comment (s) on this message. source term which was rabdead by the Soviets and published at the Vienna Conference in August 1986 is TfILE: Paper 1 summanzed in the following table:
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| AMOUNT OF ACI'lVITY RELEASED BY MAY 6,1986 Source Term Implicanons of Chernobyl H. Albrecht, B. Kuczera ISOTOPES [%)
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| xe-133 passibly up to 100 Karlsruhe Nuclear Safety Center x4-s3/85m passibly up eo loc I-131 20 Te-132 15
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| : 1. INTRODUCTION cs-134/137 10/13 Mo-99 2.3 zr-95 -
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| 3.2
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| *Ihe Chernobyl accident which occurred on April 26, Ru-103/lo6 2.9 1986,1:23 h, can be characterized as a prompt critical sa-14o 5.6 power excmsion driven by positive void reactivity sr-89/90 4.o feeM mech. Mg b Mt, b reactor power has met a peak vaue being 1-2 orders of magnitude P 8/39/4o/41/42 em-242 3.0 O above nominal conditions. The period of the excursion was esumated to be a few seconds, the transient energy Table 1: Activity release of the main radionuclides, release into the fuel may have exceeded 300 cal /g. Starting cahdead for May 6,1986 from radiometric from the steady state temperature level, the sudden energy measurements; evaluation error +/- 50%.
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| deposition may have caused fuel temperatures of 3000 C and higher, i.e. parts of the core will have reached melt .Ihe radioactive fallout in the European territory of the conditions, probably combined with some fuel USSR was estimated to be approxiamtely 50 MCI or vaporizauon. The associated pressure build-up will have 3.5% of the radioactive core inventory on May 6. These ruptured the cladding tubes whereby finely fragmented hot numbers do not include the inert gases (Kr, Xe) and the fuel was ejected into the coolant channels. Violant amount of radioactivity transponed across the borders of fuel / coolant interactions then caused a strong the USSR; both contributions to the overall source term overpressurizauon of the fuel channels with the are assumed to be in the same order of magnitude as the consequence of massive core disruption and, subsequently, 50 MCI mentioned above.
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| of the reactor building. From that moment on, a direct connection between the core region and the environment was available through which core material including fuel 3. COMMENTS ON THE SOURCE TERM particles and fission products were ejected.
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| .Ihe composition of the source term can be understood by assuming two different release mechanisms: a) Fuel
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| : 2. RADIOACITVE SOURCE TERM dispersion as a consequence of the nuclear excursion and the subsequent explosion; release due to this mechanism From Soviet informan,on, the following picture can be occurred as a large puff during the following days when derived: the finely dispersed fuel being enred over the core region and the reactor building was blown out by a flow Maj.or activity release took place during the first 10 of hot air and graphite combustion produ::ts; b) days of the accident,i.e. from April 26 to May 5. It was evaporation due to increased fuel temperature; according to stopped by covenng the destroyed reactor with boron, Soviet estimates, the temperature decreased very shortly dolomite, sand, etc. via helicopters. Due to thermal after the excursion to vaues below 2000 C; the buoyancy and chimney effects a substantial frxuon of the evaporation release was almost completely stopped on May 6, when the core region was completely covered as CHERNOBY1. COSTERENCE.BY.COMPLTER - Sept.29 . Oct.17,1986 Page El Y
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| 4 s of August 86. somewhere);
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| b)chenucal/ physical species and relative amounts of -
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| In this respect, the main question to discuss seems to radioactive products in the source term (ppints b and c of be the following: 3.1.);
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| c) plume rise on the site, in relation to the energy h
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| 3.1. WHAT IS SURPRISING AS REGARDS THE released and the meteorological data; CHERNOBYL SOURCE TERM 7 d) future of the radioactive products trapped in the plant Referring only to what we knew before the IAEA (radioactive products are still escaping from the Chemobyl conference, one can say that we were first surprised by plant, but the discussion must not be restricted to this four points: particular point; e.g., have we correctly taken into account a) the high level of the soume term, all events or phenomena goveming the long-term behavior b) its high relative content in low volatile fission of the radioactive products inside the plant, such as products and in transuranics (such as Np-239) compared to interaction of mnraminated water with corium?)
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| NUREG-772 relevant data, ,
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| c) the distribution ofiodine between its different 3.3. WHAT IS IN AGREEMENT WITH OUT chemical / physical forms (only a few available CURRENT ANALYSIS?
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| measurements reveal complete, but they all indicate a high If one excludes the rise of the plume above the site, it percentage in volatile forms), seems that the western organizations which have tried, d) the necessary rise of the radioactive plume to a very starting from the meteorological data and the radioactive high eleva: ion to explain the quick and long distance measurements made in westem Europe, to compute the l transfer. source term leaving the Chernobyl plant, made "a good l Of course, the information given later by the Soviets guess," taking into account the incertitudes on the data and l in the frame of the Vienna conference helps us to the models. So this seems to conf'um the general enderstand the four points above, but it raises at the same adequacy of the models used to compute the dispersion time new topics deserving reflection: into the envuonment.
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| e) the type of the accident (it has been underlined that But it must not be concealed that difficulties have been I chat happened in Chemobyl-i.e., high release without met in performing these computations, mainly due to:
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| warning-is a type of accident usually classified in the -Paucity of radioxtive measurements (e.g., a very few j residual risk-i.e., physically inconceivable or with a very gave the distribution of iodine in its possible chemical 3 l low probability-in the westem P.S.A.'s),
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| f) the actual release history (i.e., the variation of the forms), W I -insufficiencies in the meteorological data (e.g., rain or I
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| release rate v. time during the days following the accident, not rain?),-unusually long-distance transfer.
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| even after the dumping of materials on the disrupted core). So, even if one can be generally satisfied with the models, improvements have to be made concermng the 3.2. WHAT ISSUES NEED A DEEP INSIGHT TO data acquisition mainly.
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| CONFIRM OR REFUTE THE PRESENT WESTERN SAFETY ANALYSIS CONCERNING 4. LAST WORD SEVERE ACCIDENTS IN NUCLEAR PLANTS 7 It was tried in this paper to ask the main questions All the above points have of course to be explained as conceming the Chemobyl source term and to begin best as possible, firstly by the Soviets. But it is discussion on them without going too far in drawing necessary to sort out now the points which could call into , conclusions.
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| question our safety analysis concemmg severe accidents, if 'Ihus, the discussion during the conference-by-any. computer could now proceed as follows:
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| At the IAEA conference in Vienna, the general feeling ,
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| of the westem experts was that the Chemobyl accident a) complete the list of questions to be examined, was not in general challenging the safety analysis conceming severe accidents. Nevertheless, it is clear that b) give answers to them if possible, or at least make every nuclear-developed country is going to re-examine or comments, and to deepen some parts of its philosophy, with the objective of establishing it more thoroughly. c) make a synthesis on what we think:
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| In this spirit, it seems that the following points have mainly to be looked at: -we have leamt from this accident, a) probability of occurrence of accidental sequences of the Chemobyl type-i.e., accidepts leading to high radioactive -we have to study further, and release without a waming time. (Clearly this is not included in the source-term topic and not entirely either in -about the adequacy of our current approach conceming h
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| the other topics at the conference, such as " implications source-term research and the analysis for severe accidents for containments," but this subject has to be discussed in nuclear plants.
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| Pa O .ge HI.4, CHERNOBYL CONFERENCE.BY-COMPLTER - Sept. 29. Oct.17,1986 g .
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| : t. .,
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| LWR /PHWRs. For example,in-vessel releases are charactenzed by non-oxxiizirig conditions, and iodme and source.tenns/ intro #3, from sysop,6970 chars, Fri Sep cesian would rapidly form CsI, which would be less 26 14:42:35 1986 -
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| volatde than the 12 that is formed under oxidizing There is/are comment (s) on this message.
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| O conditions. ^ iso, the r ci wouid net ii to the Point -
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| where fuel "+>------d-= would occur. Even underin- TITLE: Paper 3 vessel fuel-melting conditions for LWRs, most of the low-volatile species would remam in the melt.
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| THE SOURCE TERMIMPLICATIONS OF
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| ' CHERNOBYL Durmg ex vessel releases, dense aerosols may be by produced by the core / concrete interacnon. However, there _
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| ALAIN L'HOMME are two important auenuanon awhaabe in LWRs that Head of Service of Analysis of Sites, Accidents &
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| were not operanng at Chemobyl First, as mentioned Contamment (SASC) previously, even an impened contamment building would Institute of Health Physics & Nuclear Safety (IPSN)
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| , adenuate aerosol emission to the environment. Perhaps Atomic Energy Commission (CEA) more importantly, both LWR and PHWR accidents are Nuclear Research Center, FONTENAY-AUX-ROSES charactenzed by extremely wet conditions in dontainment. (CEN/FAR), FRANCE It has been ?=== .ial in many experimental studies, and from the analysis of reactor accidents, that wet 1. FOREWORD conditions significantly attentuate the source term. For i
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| The only objective of this paper is to launch the example, in LWRs, aerosols from the core / concrete discussion between the participants in this conference-by-
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| , interaction would likely be relecsed to containment computer about the following topic: the CHERNOBYL
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| ; through several feet of water. 'lhe water, depending on its source-term implications. Consequently, the paper tries
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| ! depth, would effectively scrub out a good portion of the to raise the main questions without necessarily developing aerosols. No such attentuation took place at Chemobyl. a full response to them.
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| Releases After Core Covered
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| : 2. PARAMETERS CHARACIERIZING THE SOURCE TERM The final release at Chernobyl took place after the In this paper, the sourec term is understood as being
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| .. graphite fire was out, and when the core was covered with e the radioactive retmet leaving the outer containment of a sand, baron carbide, and dolomite. The higher nuclear plant. This source term is fully charactenzed by i temperatures, due to the reduction of radiative heat transfer the three following parameters:
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| from the covered core, increased the releases from the core.
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| -the levels of the radioactive releases for the different In particular, there was an initially high release of iodme, isotopes, and this may have been due to hot / oxidizing conditions in -the kmeucs of the releases, the core, leading to decomposition of Cst The releases -the chemical / physical forms of the different elements.
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| were apparently controlled by pumping nitrogen under the It is clear that problems ichw.ii and downstream of core to prevent further oxidation and to cool the core.
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| the source-term problems will also be addressed during the i Again, I expect that the presence of water in a conference, interfacing with other topics of the conference, .
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| LWR /PHWR accident would effectively attenuate long- mainly:
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| term releases. T
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| -upstream: events and phenomena happening inside the plant, govermng the parameters of the source term, and My general conclusion is, then, that the Chemobyl --downstream: dispersion of the radioactive releases into I
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| source term may not be directly applicable to the environment.
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| LWRs/PHWRs. However, the Chernobyl releases may be able to be at least qualitatively explained by the advances ,
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| : 3. MAIN QUESTIONS ABOUT THE CHERNOBYL in source term technology that have been achieved over SOURCE TERM the past 10 years. Also,ifindeed there was no fuel Of course the reasoning that leads to these questions melting (as the Soviets claim), then the accident has also stans fom the confrontation of:
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| confirmed that fuel oxidation by air (or perhaps UO2
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| -the conclusions of the safety analysis conceming severe reduction by graphite at high temperatures) can also lead accidents in nuclear plants drawn in the world before the to high releases of fission products. In any event, while CHERNOBYL accident,and there are currently many puzzling aspects of the
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| -the analysis of the data collected since April 86 on the Chernobyl source term, it is highly unl@ely that the CHERNOBYL accident, either by the measurements made l !
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| ~ Chernobyl accident will lead to the discovery of any key on the dispersion of the fission products in the western areas of LWR /PHWR source term technology that have world, or by the information given by the Soviets, in been overlooked.
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| particular during the IAEA conference at Vienna at the end CHERNOBYL COSTERENCE-BY.COMPtJTER- Sept.29 Oct.17,1986 Page 1113 \
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| hb s
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| EI'RI (Electric Power Research Institute), of Palo Alto, early failure, the release wouId be typically accompanied ,
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| Califomia, has compiled a Chernobyl bibliography. This 1- by steam and hot hydrogen from the containment -
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| bibliography includes references to some 450 articles, atmoshere. Stone & Webster has calculafed the plume joumals and other publications which deal with the energy to be in the order of 1.0E+7 cal /sec (about 42 Chemobyl AES and the RBMK type reactor. His MW), consistent with 1.2E+7 cal /sec attributed to the bibliography represents a pre-accident compilation of PWR-2 release in WASH-1400.
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| material. Articles dating from 1970 through 1986 appear in the bibliography. As reported by Karahalios & Gardner of S&W at the
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| . CSNI Aerosol Specialists Meeting, Karlsruhe, FRG, The coordination of this effort was handled by S. Levy September 1984, these energies would produce a dose Incorporated (SLI), of Campbell, Califomia. SLI has reduction of about an order of magnitude in the first few computerned this bibliography and has provided full miles, as compared to a cold release, with small increases searching capability for all the entries. at larger distances.
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| The entries in the bibliography were obtained from EPRI Copies of the paper are available on request - Stone &
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| sources and contacts. In addition, SLI used its resources to Webster Engineering Corporation,245 Summer St.,
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| collect information fmm six large de@s. managed by Boston, MA 02107.
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| the DOE, among others.
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| R. Gardner De actual information contained in this bibliography includes: source. terms /mtro #10, from pkarahalios,2692 chars, An abstract of the article; authors; sources; publish date; Tue Sep 3014:27:251986 work date; title; original language; availability of an his is a comment to message 3.
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| english translation; and other information. All this data may be searched for any word or phrase the user wants to From E.A. Warman of Stone and Webster find.
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| With respect to the rate of release, i.e. the actual release SLI has also computenzed the Intemational Atomic history, it is significant to pint out that 76% of the Energy Agency (TAEA) Report prepared by the USSR on " release", as measured by ground deposition in the Soviet g the Chemobyl AES presented at the IAEA Expert Conference in Vienna, August 1986. His report is also Union, occured after the first day. It could thus be W concluded that more than three. fourths of the release from fully searchable for any word or phrase. Chemobyl was associated with the graphite fire. (Note that the graphite fire was stated to have started EPRI, with S. I.evy Incorporated, would like the approximately ten hours after the sta:t of the accident Conference participants to be aware of this bibliography according to the oral presentation by the Soviet delegation and report and its availability. For any funher in Vienna.) All other differences between RBMKs and informatio.n or questions on this information use the mail LWRs aside, since LWRs have no graphite the three-system to contact. jdevine. fourths of the release associated with the uncontained graphite fire has no relevance to LWR source terms. Dat is not to say that the remaining one-fourth of the source. terms / intro #9, from pkarahalios,1298 chars, Tue -_ uncontamed release from the autocatalytic core dispersal Sep 3013:43:28 1986 accident at Chemobyl has much relevance to LWRs either.
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| This is a comment to message 4 It simply means that the technical conclusions as tp the lack of relevance to the LWRs of the remaining one-fourth From R. Gardner of Stone & Webster of the Chemobyl source term require addressing other issues, such as the inability of creanng autocatalytic core The effects of thermal plume energy in reducing doses at dispersal in an LWR and the effectiveness'of containments short distances is not a "surpnse" and would be applicable in western nuclear power plants.
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| to LWRs.
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| I disagree with the author's characterization that the Ahhough most generic analyses of offsite consequences Vienna conference raises "new topics deserving reflection" are based on a cold plume, this is in fact a conservative with respect to the statements wich follow under the simplifying assumption. heading "e. the type of the accident". He conference indeed raised some new topics, but the topics in item e are Source term analyses show that releases from late containment failure sequences are small and that it is only with the very unlikely case of early containment failure not among them in my opinion. For example, the Chemobyl accident is far from " physically inconceivable" h
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| for the RBMK design and, as noted above, Chemobyl was that releases of any offsite significance can be derived. In not a high release without waming, as three. fourths of the Page III 6 , CIIERNOBYL COSTERENCE.BY-CO5IPITTER - Sept. 29. Oct 17,1986 h
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| ri
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| .- i j
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| l l
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| source. terms /mtro #4, from jscarborough,335 chars, Table 1: Cumulative fractions of released fission ,
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| Mon Sep 2913:40:38 1986 products 720 hours after a core overhdating accident l N There is/are --(s) on this message. (accordmg to General Atomic)
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| ' LWR HTGR TTILE: dispersion of fission products by thermal plume xe-x. 1.0 .17 Does riot the very significant thermal energy of the Pl ume, which reponedly carned finely dispersed fuel and
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| [ $, i
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| : 2. 1.0 ,co3 graphite out of the reactor into the environment, also have sr .11 .00002 to be considered a "surpnse" and included as a new transport mechamsm in future risk assessment studies? This raises the question whether coated particles might be applicable in LWR-fuel elements. As far as I can see there are no objections. In the Netherlands some source. terms /mtro #5, from fvanuitert,3064 chars, Tue development has been done on sphere pach fuel Uncoated Sep 30 07:20:501986 uranium oxide fuel (with a density of about 88 %) was put There is/are U- ==(s) on this message. -
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| in fuel pins. It was then irradiated in the Dodewaard NPP.
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| The fuel behaviour was quite satisfactory even at a burnup TITLE: can the source-term be reduced for existing of about 30 mwd /kg. As the size of the coated panicles is plants? about the same as the uncoated particle size, probably G.C. van Uitert many of the research results are applicable. Probably even P.O.-box 20101 better fuel behaviour can be attained by mixing the coated Ministry of Economic Affairs Particles with metal particles. This would increase the heat The Hague,'Ihe Netherlands transport coefficient, by which the temperature in the fuel becomes more homogenous. The heat transfer coefficient
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| : 1. INTRODUCTION is also improved.
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| A number of barners exist between the radioactive inventory of the reactor core and the enviroment, viz. Through these phenomena the fuel temperature at
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| : a. the fuel itself accident conditions will be lower. Fewer radioactive
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| : b. the claddmg fission products are probably released. By increasing O c. the pnmary circuit NPP's safety aspects the confidence of the population in
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| ' d d. the walls of the drywell nuclear energy can be restored.
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| : e. the inner containment
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| : f. the outer contamment WHO DOES RESPOND?
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| It is difficult to improve the last four in case of enstmg LWR's (except perhaps by applying a 'FILTRA' containment filter). source. terms / intro #6, from fvanuitert,88 chars, Tue Sep 30 07:30051986 What is the situation regardmg the first barner, the fuel This is a comment to message 5.
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| itself?
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| NOTE from the author of message nr. 5.
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| : 2. SHOULD THE FIRST BARRIER BE IMPROVED? Read ' sphere pack' in stead of ' sphere pach'.
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| A hugh effort has gone into developing nuclear fuel.
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| Most of the research was directed at developmg uraniumdioxide pellet fuel. As a result fuel elements now source. terms / intro #7, from reopp,168 chars, Tue Sep have very low leakage rates and because of that the 30 10 20:41 1986 primary circuits remam clean. Nevenheless this research has to continue. Peacefull use of nuclear energy would TITLE: comment to paper #1 4
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| benefit greatly if a fuel can be developed which does not what evidence exists that the fragmented hot fuel even release radioactive fission products during core melt initiated violent fuel / cot interactions which subsequently conditions, caused pressure tube failures?.
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| ~'~~~~
| |
| : 3. SOME SUGGES110NS FOR FUEL ~ ~ ~ ~ ~ ~
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| IMPROVEMENT source. terms / intro #8, from jdevine,1666 chars, Tue A fuel has been developed for the HTGR which has a Sep 3012:01:041986 high retention compared with LWR-fuel. This IITGR-fuel ~~
| |
| l ' Oi " a e co rea P <t'eici.e. arso 4'n1so co reo I
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| '"'"c"*'"6'''''"'".'"*'''*""
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| To all Conference
| |
| | |
| ==Participants:==
| |
| particle fuel). Table 1 shows the improved behaviour of coated particle fuel compared to LWR fuel CHERNOBYL CONFERENCE.BY COMPT.TER - Sept.29. Oct.17,1986 Page III 5
| |
| | |
| t ,
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| l Fuel dispersion as a consequence of the nuclear Dere are additional comments to message 1. ,
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| excursion and the subsequent explosion; release due to this , -
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| mechanism occured as a large puff during the first phase of Question for all participants : -
| |
| g the accident and also during the following days when the finely dispersed fuel being scattered over the core region On the basis of what we know today, can we definitely W conclude that,in spite of Chemotyl fallout measurements and the reactor building was blown out by a flow of hot showing high proponions of gaseous iodine, the pre-air and graphite combustion products.
| |
| Chemobyl finding that iodine released from damaged fuel in a severe light-water reactor accident will mainly combine with cesium to form cesium iodide is still valid ?
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| source. terms / intro #13, fmm cthomasjr.,286 chars, Tue J.ROYEN Sep 3017:15:091986 OECD-NUCLEAR ENERGY AGENCY (NEA),
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| his is a comment to message 11. PARIS I WOULD GUESS THAT RESPONSES.TO YOUR LAST PARAGRAPH REQUESTING CORE source terms /mtro #17, from mgoldman,124 chars, Wed INVENTORY DATA ,WOULD SHOW THAT Oct 108:28:101986 RELEASES OF THE VOLATILE FISSION nis is a comment to message 14.
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| PRODUCTS FROM THE FUEL ARE S1hELAR TO -
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| TMI-II.(PREHAPS EVEN THE HYDROGEN). I hope lleach re-enters his comment, since the last RELEASES TO THE sentences of his first and second paragraphs are ENVIRONMENT,HOWEVER,WERE ORDERS OF incomplete. mgoldman MAGANITUDE LESS AT TMI-IL source. terms /mtro #18, from alhomme,542 chars, Wed source. terms / intro #14, from lleach,658 chars, Tue Sep Oct 110:35:141986 30 23:33:16 1986 Dere is/are comment (s) on this message. TITLE: comment for the conference manger from A I1HOMME TITLE: Graphite combustion A few points on graphite combustion may be of I feel that this new type of conference is interesting but that some improvment has to be made in the practice. If W
| |
| interest here. First, due to the low power prior to the you are interested I could give you later on my suggestion excursion, the graphite was relatively cool at the start of conceming improvment.
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| the transient,ie 280 C. It was probably cooled further by I don't believe we can achieve before today night a the initial steam release. Dus sufficient degree of synthesis concemmg the source-term Second, it should be recogmzed that self sustained topic. Could you extend tht discussion until Friday night combustion of graphite is very difficult to maintain, without disturbing the discussion on other topics? I am Blocks of graphite will not ignite in air, even if heated to available until the end of this week anyway.
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| 3000 F. A channel conflguration which limits heat loss, and provides the right air It is our expectation that Zirconium bumed first, source. terms /mtro #19, from asharon,362 chars, Wed
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| ~
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| driving the graphite reaction. Oct 110:44:41 1986 Comments would be appreciated. His is a comment to message 16.
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| . yes. Cesium Iodine is the expected form in LWR source. terms /mtro #15, from 11cach,260 chars, Wed Oct accidents. He gaseous iodine levels were the result of 1 00:00:12 1986 mechanical break up of the fuel ne high fuel vapor his is a comment to message 10. pressure required to match the system pressure,for fuel dispersal during the prompt burst, causes the high gaseous We need to be more open minded, if we are to really iodine levets %ese conditions win never occur in commericat westem i provide the level of safety necessary for Nuclear power to LWR power ptants.
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| be acceptable. Before TMI, core melts were said to be inconcievable by many. In fact,it took GPU five years to arcunm/inuo CO, hom alhomme,736 chars, Wed Oct I l get around to admitting they^. 10x401986
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| =
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| [ TITLE: Ccmment on messages 4 and 9 ,
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| source. terms /mtro #16, fmm bruegger,439 chars, Wed U**" ** *''id'"''I 'em a Chem 41. it is physicauy logical to Oct 105:38:141986 "*"*"" # ** " "# " # ''****"" # N It would be of course interestig to check if our models te c e t( ) this message.
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| C neem g um ne nergy rew Pase DI-8, ,
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| CitERNOBYL CONFERENCE.BY.COMPITTER - Sept. 29 Oct.17,1986 9
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| | |
| misase had more than a day's waming. I believe the issues was released at nree Mile Island. In other words, one resed in item e should be deleted from this paper orr the mdhon times as much I 131 was deposited arround source term impbcat ons of Chernobyl. Chemobyl as was released at Dree Mile Island.
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| (4) One would espect the larger and heavier fuel fines
| |
| . O Simdarly,I take excepoon to the author's call for to fall out closer to the point ~of release and the very small
| |
| " points that have mainly to be looked at: a) probability particles, which behave aerodynanucally like gases, to be of occurence of accidental sequences of the Chernobyl type - i..spuiiod over extremely large distances (e.g., to i.e., accidents leadmg to high ra&oactive release without Scandinavia). Indeed in describing the above data, during a waming time". First, accident sequences "of the the Vienna meeting Dr. V. F. Demin of the Soviet -
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| Chernobyl type" have no applicability to western power delegation stated that approximately 1.5 to 2% of the plants. Second, accidents involving paald early radioactive core inventory was deposited within a radius of releases have been the subject of both PRAs in the west 20 Km and approximately 1.5% beyond 20 Km.
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| and the enormous intemational source term effort. Quite However, the aggregate surface area associated with a '
| |
| contrary to this as a main point that has to be looked at, I larger number of very small (micron sized) particles would believe the Chemobyl accident does not appear to add have presented condensation sites for volatile fission significantly to this subject, which has already been products which may have far outnumbered the larger extensively stu&cd for westem power plants.8 particles which obviously were deposited close to the point of release. Thus, one would expect to observe a E.A. Warman large fraction of the volatile fission products (particularly iodine) in Scandinavia and elsewhere in westem Europe.
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| It would not be surprising to find that the amount of I-131 source terms /mtro #11, from pkarahalios,35M chars, which was transported beyond the boundaries of the Soviet Tue Sep 3015:17:041986
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| * Union substantially exceeds the 20% of the core inventory This is a comment to message 1. ofI 131 which was deposited in the European territory of Here is/are comment (s) on this message. the USSR.
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| From E.A. Warman of Stone & Webster I ask the participants in this computer conference to comment on the above observations and specifically to In addressmg the ra&oactive fallout in the European report a summary of the results of any analyses of the territory of the USSR of 50 mci or 3.5% of the fraction of the Chemobyl core inventory of specific O radioactive core inventory on May 6, the authors radionuclides, pointsparticularly of the 92 mci ofI-131 and 7.7 out that "these numbers do not include the inert gases (Kr, mci of Cs-137, which they have determined to be released Xe) and the amount of ra&oactivity i..wiwisd across the based on measurements in their countries. Rese, of borders of the USSR" and go on to state "both course, would be additive to those fractions reported by contributions to the overall source term are assumed to be the Soviets, as they relate only to analyses of deposits on in the same order of magnitude as the 50 mci mentioned their territory.
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| above".
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| Herr Albrecht and Kuczera have touched on a very E.A. Warman important aspect of the Chemobyl source term in the above quotations. My comments in this regard are as ----- ---- - ---- - - -
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| follows: sourec. terms /mtro #12, from aseltz,824 chars, Tue Sep 30 15:27:46 1986 (1) De soviet report, and presentation in Vienna, mistakenly label the 50 mci deposited in the European TITLE: Corrections to the Albrecht, Kuczera paper territory of the USSR as " Estimated releases of radionuclides from the accident". They are deposits in the The following corrections should be made to the paper USSR, not releases (i.e., not source terms). --
| |
| " Source term (2) I agree with my collegues from KfK that the non implications of Chernobyl" by H. Albrecht and B.
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| noble gas radioactivity transponed across the borders of Kuczera-the USSR are likely to be of the same order of magnitude 1. The authors are from the Karlsruhe Nuclear Research as the 50 mci deposited in the Europen territory of the Center (KfK)
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| USSR. 2. In the table, Isotopes, k4-83/85m should be kr-(3) With respect to I 131, the 20% reponed to be 83/85/m deposited in the Soviet Union translates into 18 mci of 3. In the paragraph following,50 MCL should be 50 the 92 mci core inventory as of the time of the accident mci 4
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| 0123 on April 26,1986. (This cowpunds to 7.3 mci 4. Paragraph a, under number 3, Comments on the i .
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| on May 6.) By contrast, approximately 18 Ci of I 131 source term, should read as follows:
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| CHERNOBYL CONFIRENCE-BY COMPtfrER - Sept.29 . Oct.17,1996 Page HI.7 i
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| 1 -
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| i
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| "_ _ _ _ _ _ . - - _ . . _ _ . _ _ - _ . , n _ _ _ . _ .
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| consequently G the rupture of all channel tubes. All that We found that a reactivity insertion of about 350 cal /g is of course an a posteriori analysis, using in particular a, ,- produced a molten fuel coolant interaction which resulted reconstitution by computer of the phenomena involved.
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| , in a steam explosion and fragmentation of molten fuct The debris consisted of ruptured, rounded, hollow particles g
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| with many voids in the walls. I bgree with Albrecht and source. terms / intro #26, from alhomme,610 chars, Wed Oct 114:11:07 1986 Kuczera that the 3 - 4 % release fractions of low volatile and refractory fission products in the initial explosive TITLE: comment to messages 10 and 15 release and in the subsequent five days of decreasmg releases during the time the reactor core was being covered I did not get entirely message 10 on my screen. But it seems to me that the author is misunderstandmg my paper with various matenals are consistent with the release of fuel particles. The initial release was likely due to the
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| : 3. Perhaps it is a bad effect of my poor and oversimplified english. direct expulsion of fuel fragments and the release during I don't say that I worry very much about the the next five days may have been due to the resuspension possibility to have a Chemobyl type accident in westem 'of fuel particles by strong up flow of air through chimneys in the hot, burning core. The accumulation of PWR's: I feel this is physically inconceivable. But what I matenals dropped on top of the reactor core tended to cool want to underline is that we have to give a lock, after the core by absorbing heat, including the heat of fusion, Chernobyl, to the statements which led us in the past to say so. which caused the overburden to melt. In addition, the overburden in both solid and liquid forms probably In other words, as author of message 15 is writing, it is important,in safety business, to stay open-minded. provided some scrubbing of the aerosols exiting the core.
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| The releases after day six which showed increasing fractions ofiodine and cesium relative to the low volitles source. terms / intro #27, from alhomme,866 chars, Wed are likely due to vaporization associated with increasing core temperatures and oxidation of core materials after Oct 114:31:181986
| |
| --- meldng the overburden. Finally , the elimination of air ingress at the bottom of the reactor by the introduction of TITLE: comment to messages 16 and 19 nitrogen gas provided core Physical. chemical forms of iodine in source-term of severe accidents are depending:
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| cooling and elimination of oxidation processes.
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| - first of the fuel environment durring degradation (e.g.
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| temperature, H2, control rod aerosols...),
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| It would be informative to retrieve radioactive debris from the surroundings of the Chernobyl site and from h more remote locations where fallout occurred and
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| - second of the residence time inside the containment:
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| characterize the physical, chemical, metallurgical, and different chemical reactions develop inside the gaseous isotopic nature of the material. These results should then phase and the liquid phase (in particular it is not very be compared with debris characteristics from previous RIA casy to predict what happens in the liquid phase and what is the testing. The debris can be expected to supply the evidence equilibrium constant of different forms of iodine between requested by R. Copp in this conference (message #7) to the gaseous and liquid phases). determme whether or not a steam explosion occurred.
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| It is fortunate that reactivity insertions of the energy Anyway for western PWR accidental sequences, it seems experienced in the Chemobyl reactor are not possible in
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| ( that Csl is the major iodine form in the source-term. It is Westem nuclear power plants. I tend to agree with
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| ' obvious that research has to continue in this area. For Torgerson that it is not likely the Chemobyl experience Chemobyl case, it seems to me that explanations given in papers 1 and 2 are sufficient. will point to areas of severe accident source term technology that have been overlooked. I do think it is It is 7.40 pm in France now: I am going back home.
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| Oood-bye. important to demonstrate that we understand what happened at Chemobyl and that this understsnding falls
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| ( within the context of our severe accident technology data base.
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| source. terms / intro #28, from rhobbins,2997 chars, Wed Oct 115:02:511986 R.R. Hobbins There is/are comment (s) on this message.
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| TITLE: Comments to All Source. Terms Conference s urce. terms /mtro #29, from ani,518 chars, Wed Oct 1 Participants 16:09:24 1986 An important aspect of the Chemobyl accident is how it This is a comment to message 3.
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| fits into our unders:anding of severe accident technology. ~
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| We have performed a series of reactmty uutiated accident OUESTIONS ON THE SOURCE TERM (RIA) tests at the Idaho National Engineering Laboratory IMPLICATIONS OF CHERNOBYL which, along with more recent source term research .
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| provides a basis for understanding the Chemobyl accident 1. What were the radiation levels downwind of Pap m-10
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| ^ CHERNOBYL COSTERENCE.BY-COMPLTER - Sept. 29. Oct.17,1986 M
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| l , ,
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| l are able to predict the Chemobyl plum rise with a good I consder that these 2 papers give the good techrucal
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| ' ~
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| accurracy. But they are at least 2 difBculues: answer to my point 3.2b in paper 3. But:
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| - take a good account of the particular meteorological - point 3.lf has to be studied further (release history p conditions during the first night of the accident, during the days following the, accident), . .
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| V - make a good guess of the energy release. - point 3.2a also (I share the general point of view of the I agree with message 9 : it is not expected to have such authors of papers 1 and 2 about the probability of
| |
| . an energy release for ustern PWR severe accidents, what occurrence of Chernobyl type accidents for westem water is conservative for radiological consequences in the near reactors, but I feel that the demonstranon has to be envuonment. arg-aA more deeply). *
| |
| - I make a special comment on one technical point developed in paper 2 (Hello Dave, see you next week in source termsfatro #21, from zrevesz,552 chars, Wed Paris: if you organize a dinner in Ile Saint Louis, I am Oct 111:00:401986 ready to participate to prolong the discussion .): my i 'Ihis is a comment to message 1, -
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| distinguished colleague considers only the positive effect of water above corium -fission product filtration-; a Questions to the authors of the initial paper from Dr. B. negative effect resuspension- has also to be considered, l Pellaud, Elecnowatt Eng. Serv. : '
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| * because this water, after some days is very contaminated, i The table of your paper entitled ' Amount of activity containing almost all cesium and iodine, especially if
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| . released was questioned by participants at the Vienna there is connection between the vessel cavity and the conference as to the consistency of the figures. In remaining bottom part of the contamment. -
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| particular Mr. L'Homme stated there that some nuclides were some 100 times too high in compenson with French estimates (Cs,Zr). source. terms / intro #24, from asharon,553 chars, Wed Oct 111:31:371986 Question #1: Are these di=% esi in the Russian 'this is a comment to message 7.
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| informanon : A.+i one month after Vienna? There is/are comment (s) on this message.
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| ~
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| Question 2: If so, what could be the cause of these To my knowledge there is no clear evidence to the exact
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| - discrepancies?
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| ' mechanism of tube failure. It could have been the result of
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| ; overheating due to direct contact with hot fuel debris that j
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| * was ejected through the ruptured cladding. There are j source. terms /mtro #22, from zrevesz,718 chars, Wed however some emarwatal evidence from PBF tests and j Oct 111:11:041986 TREAT that fuel shattenng in a power burst generates j '1here is/are comment (s) on this message. " fuel dust" with particle sizes of the order of few microns If this hot fuel dust comes into contact with the coolant, i TITLE: Test Scenanon violent boiling can produce a steam spike and may have 4
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| A basic quescon from A. Jacobi, Jr., Electrowatt Eng. further contributed to tube failure.
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| Serv.
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| 4 At the beginning of the test which proceeded source terms /mtro #25, from alhomme,972 chars, Wed
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| : immediately the Chemobyl accident the stop valves to Oct 111:39:541986 turbme 8 were shut closed. The reactor was operaung at this time at a 200 MW(th) power level (but it was TTILE: comment on paper 1 and message 7 foreseen to nm this test at 700 MW(th) reactor power As an expert of INSAG, I participated in the Vienna
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| ; level). Since turbogenerator No. 7 was already isolated conference at the end of August and in the writing of the
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| ; beforehand and there was no incentive to scram the reactor, INSAG report during the following week.
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| i the power and hence steam generation in the primary , The soviet experts have in this frame said the j circuit should have continued during the whole test period following things and, as far as I know, no westem expert at the objected.
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| l same level / rate. Does anybody know where this steam - a criticality excursion happened and led to the
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| ! would have been routed to in case the test would have dispersion of part of the fuel in the coolant, then to a been camed out successfully? steam explosion. 'Ihe l'ust failure of the channel tubes was mainly due, not to the pressure increase in the tubes, but to the loss of mechanical properties of Zr resulting from i source. terms / intro #23, from alhomme,1074 chars, Wed radiative heat exchange between the hot fuel fragments
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| { Oct 111:18:131986 suspended in the coolant and the tube wall;
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| - this led to a pressure increase in the core compartment,
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| ! 'ITILE: comment on papers 1 and 2 thus to the lifting of the upper shielding plate, i
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| ! CHERNOBYL CONTERENCE.BY COMPtJrER - Sept.29 Oct.17,1986 Page 1119 4 Y
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| - ,.--,m--._ - , -v- -- - - - , . ,--,- - - - - - . ,, n , - - - , -, -. ,-, -r-- - ,---------,w , -- -
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| of the test, as the Soviets report, bypassing steam flow to easily be above one dollar, can cause very sharp IWW '
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| , TG 7 would be a slow process of reaching synchronous power spike and damage tha fuel But the amount of speed and synchronizing to the grid. Also,it appears that energy,i e. the duration of the power spike 7would not be g the test involved quick closure of the TG 8 stop valves. It high enough to cause fuel shauering and eventually W seems unhkely that TG7 could structurally handle the ejection from raptured clad in the form of fuel dust as in quick increase in steam pressure, even if TG 7 was at the power burst tests like TREAT, His is very surprising synchronous speed at 0% load. especially for low enriched fuel like RBMK or LWRs.
| |
| However, I certamly agree with Mr. A.Sharon that this is the case for very high enriched fuel,e.g. over 90% of -
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| source. terms /mtro #38, from halbrecht,557 chars, nu U235, According to 'IREAT test participants they have Oct 211:31:141986 never observed any fuel shauermg or any fuel dusts with This is a comment to message 21. small particles in LWR type of fuel tests.
| |
| Therefore, my question to MrR.Hobbins (to his We do not know these French estimates,if they were , message # 28) is: If INEL RIA tests are valid for LWR made for severe accidents in Westem LWRs, the expected fuels,then why are we still saying "WE FEEL THIS IS release fractions for Ru, Zr, Np, Pu, . would - of course - PHYSICALLY INCONCEIVABLE?" Even though,we be lower than 1 - 5 % by several orders of magnitude. For know that some scenarios postulated for LWRs can Chernobyl, the high release of these elements was only introduce more than one-dollar worth of reactivity (prompt due to the dispersion and transport of very small fuel criticality) Of course,other phenomena such as Doppler particles. Since release due to this effect does not occur and coolant conditions have also be considered during the according to the volatility of the fission products, we do burst. But in terms of individual fuel tubes configuration not see any discrepancies in the release tables presented of RBMK there is no big difference between CANDU by the Soviets at the Vienna Conference. pressure tubes or to a certam extend with in-channel conditions of a BWR bundle, except the void coefficent i.e., the direction of the feedback. Plus, we always count source. terms / intro #39, from wrossbach,344 chars, nu on our comprehensive protection systems to tum over the Oct 212:24:071086 power in less than 2 seconds except in ATWS conditions.
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| Herefore, TITLE: A question to all participants from G. Lohnert, Interatom GmbH, Germany.
| |
| Additional questions on RIA are:
| |
| a) what was the energy deposition (cal /gr) g b) duration of burst in hot spot (sec.)
| |
| ne fission product Xenon is a strong neutron absorber. c) surrounding coolant condition (e.g. pressure, void In addition, for elevated fuel-element temperatures it is fraction)?
| |
| highly volatile. Is it conceivable that a rapid loss of Xenon enhanced the reactor, excursion which had been Comments on related computer modeling of the event triggered by the positive void effect? (related messages #25 and 33):
| |
| On the posteriori analysis of the event with computer j models, as in the Soviet presentation. To IAEA or source. terms /mtro #40, from mkarasulu,3812 chars, EG&G's RELAP5 and BNL's MINET predictions cannot Du Oct 215:34:001986 give an answer (for the sequence of even's up to the first explosion) to my first question above. However, with TITLE: comments to messages 7,24,24 and 33 these models you can predict the amount of reactivity To: All source. terms participants msertion and consequently the power excursion only on a From : M.Karasulu,New York Power Authority core-wide basis. Therefore, LOCALIZED power excursion
| |
| ; Subject : Comments on initiating-event scenario calculations and the duration of the power spike should be j - - resolved first to hypothesize the fuel shattering and the l Related messages 7,24,25 and 33 of this conference. following localized steam explosion.
| |
| l According to MINET code predictions,BNL concludes l First of all I thank Dr.Torgerson for his kind response that:
| |
| l to our questions and all participants for their valuable, 1- Broad agreement in analysis suppons Soviet enlightening comments and suggestions. We learned alot explanation.
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| about source term in last two days. He following issue, 2- Most mysteries now resolved,some remains e.g.,
| |
| however, appears to be still remains unresolved. It appears wonh of control rods.
| |
| that we still have significant doubts about the initiating 3- Core-wide power peak marginally large enough for event scenario given by either Soviets or as conjectured by severe damage. May need RAMONA cales to determine our phenomenological expectations. local peak.
| |
| Panicularly, the sequence of events up to the first explosi.on is a blur. The amount of positive reactivity source. terms /mtro #41, from psviatoslavskyx,645 ,
| |
| l mserted due to steaming of under-cooled tubes, which can chars, nu Oct 2 15:47:56 1986 l
| |
| Page III 12 CHERNOBYL COSTERENCE.BY. COMPT,TER - Sept. 29 Oct.17,1986 (O
| |
| | |
| Chernobyl as a function of time and distance durmg the drive graphite oxidanon.
| |
| Erst few days of the accident? Can this data be used in any 6) Graplute/ water reaction was probably not way to confirm the models used in U. S. source term significant, as graphite was cool when water was available, and no water was,a, vailable later.
| |
| (a~T work?
| |
| : 2. Can the source terms reponed by the Soviets at - - -
| |
| Vienna be verified by observanons outside the Soviet source. terms /mtro #33, from lleach,325 chars, Du Oct Union? Can transport models be verired by observations 2 02:04:55 1986 outside the Soviet Union assuming the source terms are his is a comment to message 22.
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| correct?
| |
| De reactor should have scrammed at test initiation due to the two TG isolated scram, source. terms /mtro #30, from donf,778 chars, Wed Oct It was overridden, and it was not stated what was 1 17:41:23 1986 +
| |
| intended.
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| This is a comment to message 22. We have had RELAPS analyses performed of the Dere is/are comment (s) on this message. . transient.
| |
| Dere are additional comments to message 22. We can't keep the pressure down without steam bleed, prior to the experiment.
| |
| De steam flow bourAj condition during the test and There's something they neglected to tell us!
| |
| for the 4 minutes preceding the test remains a questionable area. De steam flow and separator pressure information -- --------- -------- ---
| |
| shown in figure 4 of the USSR report appean to be source. terms /mtro #34, from lleach,259 chars, nu Oct inconsistent. If all steam outlet flow were termmated as 2 02:08:34 1986 this figure suggests then coolant system pressure would This is a comment to message 24.
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| have risen. Since the pressure information in this figure represents actual plant data, while the steam flow De tubes will fail at 800 C or so at nonnal operating represents a calculation, I would believe the pressure pressure.
| |
| , response is correct. His would imply there was steam Calculations we have done indied tube rupture outlet flow up to the time of the explosion. It is suspected propogation is probable.
| |
| Os this steam was bypassed to condenser, or perhaps turbogenerator 7.
| |
| to his would occur due to mechanical loading transmitted through the graphite.
| |
| Remember the control rods that went clunk?
| |
| comment to message number 22 from Don Fletcher,EG&G Idaho source. terms /mtro #35, from 11each,205 chars, nu Oct 2 02:15:23 1986 source. terms /mtro #31, from cthomasjr.,179 chars, Wed his is a comment to message 28.
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| Oct 117:53:161986 Hi, Dick. Here was a fellow with the US delegation in
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| ~1 TILE:'IO: Conference Marmger , Vienna who mentioned finding minute fuel fragments in I would like to support the suggestion of A.L'Homme Sweden. He said they showed evidence of fracture, not to extend the discussion of source tenns if at all possible. melting. Can anyone confirm?
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| Larry Leach source. terms /inem #32, from lleach,736 chars Thu Oct - -
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| ; 2 01:58:44 1986 source. terms /mtro #36, from lleach,93 chars, nu Oct 2 02:18:11 1986
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| . TTI'LE: Graphite Combustion Revi This is a comment to message 30.
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| l His is r revisicn to my slightly distorted message on graphite ombustion. De points I wished to make were as Hi, Don. I assume this is based on the RELAPS follows.
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| calculations you folks did for us? Iarry Leach
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| : 1) Initial graphite Temperature should have been low due to low power operation, ie. 280 C. ,
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| 2)It was probably funher cooled by the stcam release. source.tenns/mtro #37, from psviatoslavskyx,484
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| : 3) hus,its contribution to the early FP release was chars, nu Oct 2 10:37:15 1986 0 9 e64) 6ir te et 6e t i = a aei x reie e.
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| Graphite is VERY difficult to bum.
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| Twis i ee t te-e se 3o.
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| ]
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| : 5) Early bunung in reactor (ie 10-24 hours) was Bypassing steam flow to turbogenerator 7 (TG 7) would probably driven by remaining Zuconium, which would be a tricky thing to do. If TG 7 was not in use at the time CHERNOBYL CONTERENCE.BY.COMPtJI'ER - Sept.29. Oct.17,1986 g
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| Page III.11 %
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| above about 300 cal /g. The threshold for severe rod in that subject,it is message no. 27. '
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| damage and loss of geometry is about 240 cal /g, although. Marshall Berman $
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| rod failure has been observed at 140 cal /g. A best -
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| g estimate steament by Brookhaven National Laboratory W indicates that the greatest peak axial ruiial average source. terms /mtro #52, from ha!brecht,621 chars, Wed enthalpy possible in a U.S. LWR is less than 110 cal /g. Oct 15 08:29:051986 Therefore RIAs do not pose a safety concem in U.S. This is a comment to message 21.
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| LWRs.
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| ==References:==
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| To Zsolt Revesz P.E.MacDonald, et al. "A cetement of Light Water Please excuse me for answering so late: It is quite clear Reactor Fuel Damage During A Reactivity Initiated . from the release mechanisms that all westem estimates Accident," Nuclear Safety 21 (1980) 582-602. lead to much smaller release fractions for the low volatile M.S.El Genk, R.R.Hobbins, and P.E.MacDonald fission products. These are normally based on release by
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| " Fragmentation of Molten Debris During A Molten Fuel vaporization during core melt accidents. Release by fuel Coolant Interaction," J. of Nuclear Materials 113 (1983) dispersion to the environment are excluded, because 101-117. accidents of the Chemobyl-type are ruled out for westem M.S.El Genk, R.R.Hobbins, and P.E.MacDonald, LWR's.
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| " Molten Fuel Coolant Interaction During A Reactivity Considering the unavoidable uncertainties in summing Initiated Accident Experiment," Nuclear Engineering and up all measured release data we presently do not see any Design 66 (1981) 247-267. discrepancies in the data published by the Soviets.cf. table of message #1.
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| H. Albrecht source. terms /mtro #48, from jguy,277 chars, Mon Oct 6 05:19:29 1986 source terms /mtro #53, from mnhl,9141 chars, Fri Oct TITLE: SOURCE TERM DESCTRIFITONS 17 20:47:17 1986 APPENDIX 4 OF THE RUSSIAN DOCUMENT There is/are comment (s) on this message.
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| PRESENTED AT VIENNA CONTAINED VARIOUS TABLES OF MEASURED AND PREDICTED RADIOISOTAPE ACTIVITIES IS THERE ANY TITLE: MNH STEAM EXPLOSION COMMENTARY TO: AllInterested Readers g
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| EXPLANATION FOR THE APPARENT FROM: Michael N. Hutcherson DESCREPANCY IN 134 OS/137 CS ACTIVITY Fauske and Associates RATIOS /? 16WO70 West 83rd Street PETER JONES, CEGB , UK Burr Ridge, Ulinois 60521 s
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| USA source. terms /mtro #49, from jmatuszek,190 chars, Wed 312/323-8750 Oct 8 09:49:011986 RE: COMMENTARY ON THE OCCURRENCE OF
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| ------ A STEAM EXPLOSION DURING THE CHERNOBYL TITLE: Question on a Comment by mhurcherson ACCIDENT In the comments on " containments", message #26 by DATE: 17 October 1986 mhutcherson reffered us to " source. terms" for the full text.
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| I can't seem to find his comments. I do apoligize for the slight delay since I originally put my note in the " Containments" section on 6 Oct 86 (Message 26), but here it is finally.
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| scurce. terms /mtro #50, from mberman,422 chars, Wed Oct 813:29:061986 CLARIFICATION OF THE TERM " STEAM EXPLOSION" l TTI'LE: COMMENTS ON S'IEAM EXPLOSIONS - I would like to respond to the claim that has been (Garbled) made that a steam explosion was panicipant in the
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| ; Chemobyl accident. To my knowledge, no " direct l evidence" exists that the fragmented hot fuel (and cladding) source. terms /mtro #51, from mberman,309 chars, Wed initiated a fuel / coolant interaction (FCI), however, at the Oct 813:32:201986 same time, this is a very plausible explanation of the observed behavior. Caution must be taken in this case in TITLE: COMMENTS ON STEAM EXPLOSIONS ascribing the level of energetics to this potential FCI.
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| Specifically, the te:m " steam explosion" has been floating Message 50 was somehow garbled. It says that a around in some of the discussions that have followed discu'sion on steam explosions has been added to the Chemobyl, and it is on this point that caution should be conference on Containments. For those of you interested exercised. The occurrence of a technically legitimate
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| _ Page III.t4 CHERNOBYL CONFERENCE.BY-COMPtTTER - Sept. 29 Oct.17,1986 Y
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| This is a comment to message 1. term, stamng only from the meteorological data and the radioactive measurements made in western Europe To H. Albrecht: (concentranons in air, plateout on ground) and using
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| (
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| current atmospheric dhpaus codes. We found (this is in !
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| In your introduction you mention that during the our report IPSN2sa6 revision'2) that about 20% of the transient, reactor power met a peak value of 12 orders of volatile fission products as Cs and I must have left the magnitude above nominal conditions. In an EPRI plant. Lookmg at relative ratios beetween Cs and low Presentation (ref 1) , it is stated that there were two power volatile fission products in the radioactive measurements
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| . surges, the first to 110 times full power, the second to made in western Europe, we found that these low volatile 400 500 times full power. The presentation also states fission products were in excess by some orders of that the " Soviet model suggests" these power surges. magnitude compared to NUREG 772 data. As NUREG Have you heard of these numbers used by EPRI? 772 data are relevant to volardintion of fission products from melting fuel, this irvirmwt hat t some phenomena, (1) EPRI Presentation on Chemobyl . other than fuel melting, must have played a role.
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| The Soviet RBMK 1000 Design Obviously dispersion of finely divised fuel outside the The April 26,1986 Accident plant is a good explanation.-
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| G. Vine, Revised September 10,1986. r P. Sviatoslavsky source. terms / intro #45, from abrachet,735 chars, Fri Oct 311:39:491986
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| : source. terms / intro #42, from mryan,654 chars Thu Oct
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| ! 2 16:04:42 1986 TITLE: general questions to all participants from i
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| - brachet.delalande electricite de france
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| 'I1TLE: Timing for Reproduction of Conference I a global and overall assessment of source term has Proceedmgs been established but does anybody have indications on the To all Chemobyl conference participants: time distribution of the released fission products I Te Pu i I have received several queries about when the proceeds of this conference will be available. It is our intent to edit the doses to the populada seem for the upper values out computer garble and reproduce the proceedmgs as soon hnked to external irradiation or contamination by as possible after the conference's conclusion. We are mhalation during the hours precedmg the evacuation, uncertam how long this will take, since we do not know can this be confmned?
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| how large (or how full of garble) the pruasiings will be, what is the origin of the doses received by the ,
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| ! but we hope to have the pages ready for reproduction populadon at this time period (nature of the P>F)?
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| within two weeks after the conference's end. Printing and 3 what were the radiological pantection measurement maihng would then take a week or so more. Margaret equipments: radiometers (gamma ambiant) or aerosols Ryan, McGraw-Hill Nuclear Publications activity from samples?
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| source. terms / intro #43, from halbrecht,348 chars Fri source tenns/ intro #46, fm jrmaio* 338 chars, Fri .
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| l Oct 3 09:37:241986 Oct 315:37:451986 i
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| T171.E: Comment to message 10 t The peak power mentioned in the introduction of our Quibbling over whether a first-day release of 25% of the
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| ' contribution (#1) should be considered i dme source represents a "high release" is symptomaue rather as qualitative than as quantitative figures. Since we of :he position taken by many m the U.S. power industry.
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| I did not perform detailed calculations on that question we Release of 5% of the core inventory on that first day is
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| ! would appreciate to get a copy of the cited EPRI report. still a large release. The issue raised in Paper 3 appears to
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| , Thank you in advance be a valid one.
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| H.Albrecht source. terms / intro #47, from rhobbins,1141 chars. Fri
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| , source. terms / intro #44, from alhomme,1049 chars, Fri Oct 318:03:261986 Oct 31039:571986 TITLE: Comment on message #40 TITLE: comment on messages 21 and 38 'Ihere is much literature on RIA testing from several O Sorry, I did not notice message 21 until today. series Before to at the INEL and numerous tests conducted conducted have the soviet report on the Chemobyl accident , we by JAERIin Japan. Fuel fragmentation has generally made in France an evaluation of the Chemobyl source been observed at axial peak radial average fuel enthalpies CHERNOBYL CONFERENCE BY COMPtTTER- Sept.29 Oct.17,1986 Page t!!.13 l
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| :- - ._-, - - = _ = . = . .- - -, - . - - _ _ - - . . - _ , - - - . . - _ . ._
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| matrix of graphite may have become the " slug" above the evidence to support this claim. His is also the difficulty '
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| interaction / blowdown zone that may have initially broken encountered in supporting the claim of a steam explorian the upper boundary of the core compartment. in most large scale, in-pile, integral tests,-and the IN
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| ==SUMMARY==
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| , based on what is technically known applicability of such information to genuinely to be required to initiate and sustain a steam explosion, understanding westem style LWR core damage scenarios, and our best knowledge of the conditions within the Extreme care should be exercised in attempting to translate Chernobyl core immediately before the core dtsruptive what apparently occurred in Chemobyl to western style event, it is difficult to positively conclude that the LWRs panicularily in view of the current consensus of observed damage is the result of a technically valid steam the knowledgeable community that such explosive explosion. However, at the same time, due to the rapid interactions may be dimiwd in the latter reactor group power burst and the most probable fine fragmentation of based on well controlled confirmatory experiments.
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| the fuel and cladding that resulted, whatever interaction /
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| occurred started at the fine fragmentation stage. Other mechanisms were available, and probably at play, that source. terms / intro #54, from mbennan,131 chars, Mon could have individually, and in unison, produced the Oct 2014:17:441986 citnessed damage. For purposes of genuinely Ris is a comment to message 53.
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| understanding the Chernobyl event and taking what we can team from it and try to improve the safety of our own Comment on Steam Explosions reactors, it is not wise, nor does it serve any productive purpose, to simply allege that a steam A comraent on M. N. Hutcherson's discussion is given explosion was at play in this event when there is no solid in message 48 in the Containments Conference.
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| END OF SOURCE TERM CONFERENCE O
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| I l
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| 7 O
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| se Page III.16 CHERNOBYL COSTERENCE.BY.COMPtJTER Sept. 29. Oct.17,1986
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| steam explos on in this particular event is simply not TRIGGERING OF EXPLOSION. De comment known and is only speculation at best at this point u has been made a couple places in this conferecne that a because there is no solid proof to support the claim. .His steam explosion is predicted (a verified to some extent) to
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| . is not to say that an explosive type of event did not occur not occur at high ambient pressure (greater than about I within the Chernobyl core due to the rapid reactivity Mpa).nis is ture in the abse6ce of an extemal trigger.
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| msernon (perhaps prompt critical) thus creating steam at a However,it has also been shown that steam explosions very fast rate as we certainly do know occurred. However,
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| ' can be "made" to occur at higher ambient pressure when this should not automaucally be labeled a steam _ the external trigger is commensurately more energetic.
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| explosion. A distmetion needs to be made here between his is certainly not to say that such an explosive event the " free contacting" mode of steam explosion that has occurred in Chemobyl, however, at the same tir:e, the i
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| . been hypothesized in westem style LWRs which consists potential triggermg effect of the power burst (ar.t ensuing of five (5) major steps (course fragmentation, triggering, interactions) were most probably quite energetic. When it fme fragmentation, contamed interaction zone, and all boils down, and an objective look is taken at the expensen of the coolant vapor) and the event which factual information, it is most difficult to make any occurred at Chernobyl. I agree in concept with Dr. convincing and defensive statement (s) about a steam Berman's comment that differences in definition of a steam explosion in this event.
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| explosion is not going to resolve what some people still consider as an issue in LWRs. But before an interaction
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| - OTHER POSSIBLE DISRUPflVE MECHANISMS is claimed to be a steam explosion, one must very clearly There are at least two (2) other conceivable know what is scientifically meant by that! Concerning mechanisms that could have individually produced the the necessity of a shock in Dr. Berman's definition of a damage wimessed at Chernobyl. Furthermore, in reality, steam explosion, such a shock is not nearly as important the following two mechanisms may well have acted ;
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| in this setting as in a chemical explosion because the somewhat in umson to produce the observed damage.
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| amptitude of the steam explosion pulse is much less and its wavelength is much longer. In contrast, the major VIOLENT FILM BOILING. This type of heat damage potential as a stea a explosion is produced by the transfer probably occurred heaw the temperature
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| , expansion work done by the steam rather than by the difference between the overheated fuel, etc and the water
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| - l shock-ambient interaction.
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| coolant was ver. If such a large heat flux occurred over s -
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| the extensive heat transfer surface area produced by the REQUIREMENTS OF STEAM EXPLOSION finely fragmented, yet partially solid fuel, this could no s Due to the power burst in Chernobyl, if the doubt have produced steam faster than it could have been
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| ; foregoing explosive scenario did in fact occur, it started at relieved thus ovspaming the pressure tube (s') and the fme fragmentation stage and thus did not experience eventually the core compartment thus leading in large part
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| ; the previous two stages of course fragmentation and to the observed damage. His illustrates a fundamental triggering that are required in the " free contacting" mode of difference in safety philosophy and design between this interaction. In addition,if a power burst was the i pressure tube reactors and westem style LWRs. Namely, fundamental cause of what ensued, this required the the lauer can withstand a fuel rod (s) mechanically channels to be parually voided, and hence only a limited disassemblying due to such a power burst, as in the amount of water was available in the pressure tubes to Chemobyl case, without breaching the primary system, participate in a hymeaN steam explosion. Also,if the whereas, the former can not. '1he ensueing local
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| ; Chernobyl event did start at the fine fragmentation stage, pwiution effect may well have been the mechanism not all of the fragments were liquid, and the solid that propagated the failure to surrounding pressure tubes fragments could not participate in what is legitimately that had been weakened during the power burst.
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| termed a steam explosion. De development of a ,
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| potential, initially finely fragmented state is a fundamental I BLOWDOWN OF THE PRIMARY SYSTEM.
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| and extremely important differer:ce from the necessary Given that the pnmary system was breached in a few or j conditions in western style LWRs which require the two e more pressure tubes in effectively a simultaneous rupture initial steps of course fragmentation and triggering in the by the rapid reactivity insertion, the blowdown of the free contacting mode to produce such an interaction. It is primary system from the initial precure of about 6.5 Mpa precisely these two steps that have been shown to be could supplied enough energy by itself to rupture the extremely difficult to produce in westem style LWRs, and upper boundary of the core compartment. His is thus, the steam explosion scenario in these reactors is primarily because this compartment was designed to considered to be highly incredible. Hus the choice of the remain intact for the failure of only one (1) pressure tube.
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| words used to describe the Chernobyl scenario, if a steam Of course, in reality, the observed damage may well have explosive event is o be considered, is important and been the combined result of simultaneous violent boiling should be technically correct because their meaning and in the pressure tubes and system blowdown through the implication are very different in these two vastly different broken pressure tubes. At this point,it is not type of reactor designs, t unconceivable to imagine that the originally rather tight
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| , s CHERNOBYL CONFER"NCE.BY.CO%iPtJTER- Sept.29 Oct.17,1986 page III.13 f
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| +
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| m__ . ___ _ _ __ ____ - _ _ _ _ _ _ _ _ _ . _ _ - __--___ _ _.
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| setting release mitigation targets. a reactor pressure vessel is usually more than 1 to 2 hours and thus allows for some counter meastres (accident Swedish experience so far indicates that substantial , management actions). -
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| g improvements in the capabilities of containtnents to cope W with severe accidents can be achieved at moderate costs - Containments can withstand higher loads than they compared with total plant investment. were designed for.
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| ==REFERENCES:==
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| - Buildings surrounding the containment have a good
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| : 1. L. Hoegberg,De Swedish Program on Prevention potential for fission product retention, and Mitigation of Releases in the Case of Severe Accidents. Proceedmgs of the ANS IntemationalTopical -If an early failure of a containment can be avoided, Meeting of Thermal Reactor Safety, San Diego, several hours or even days are available before Califomia, Feb. 2-6,1986. containment failure. His time period allows for
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| : 2. Nucleonics Week, Jan. 2,1986, p. 9. - appropriate accident management actions.
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| containments / intro #2, from sysop. No entry. - Design improvements decrease the potential of a release of radioactive material. Here is growing consensus that some mitigation measures can reduce the containments / intro #3, from sysop,4698 chars, Tue Sep risk substantially.
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| 30 15:45:46 1986 When analyzing the accident at Chemobyl and TrILE: Paper 2 comparing the phenomena wim those in postulated core melt accidents of western Light Water Reactors, the author Implications for Containments would like to expn:ss his personal and first assessments:
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| Prof. Enno F. Hicken Gesellschaft fur Reaktorsicherheit 1) A major difference exists for the energy input. Due to Federal Republic of Germany the super-prompt critical power excursion with a level up to several hundred times the design power, the energy Nuclear power plants must be designed and operated so that the public is protected as reasonable as achievable input into the fuel and coolant happened within seconds.
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| In core melt scenario without those power excursions the g
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| against the release of radioactive products without undue heat input (mainly decay heat) occurs in the range of risk. hours. Herefore only preventive measures are possible s for reactors of existing RBMK. type, e.g. avoidance of a It is generally agreed that the prevention of an accident is large positive void coefficient, a fast and redundant shut of highest priority. However, there is an increasing down system, decisions related to safety should be shifted demand to study and possibly mitigate the consequences of from the operators to an automatic protection system, etc.
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| severe accidents.
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| : 2) He temperature of the graphite, resulting from a high
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| ; The reactor safety systems will be operated with the initial temperature, several exothermal and endothermal l
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| objective that a release of radioactive products to the . reactions and decay heat from the fuel, causes a long-time environment is limited to acceptable doses. It is fission product release. In light-water reactors without postulated that an active or passive component of the graphite the melt temperature decreases usually within reactor system can fail, e.g. pipes, valves, first shut-down hours resulting in rnajor decr-me in the release of fission system, etc. A failure is not postulated,if the possibility products.
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| l of a t'ailure is extremely low, e.g. the failure of a reactor
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| ! pressure vessel. 3) It has been stated by the experts from the USSR that the existing RBMK design with compartments designed to
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| ; Nuclear power plants are usually equipped with a leak e witstand the load from a failure of a single pipe or header tight containment, designed to wimstand the loads from was obviously not capable to withstand the loads from failures as stated above, one or more power excursions. If those power excursions
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| . could not be brought to an acceptable low probability, it Risk studies, the accident at TMI and results from safety should be studied further,if a containment could be research led to considerations how containments react to designed to cope with the loads from power excursions.
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| severe accidents with postulated scenario including core mell At least the results, listed below, should be 4) He analytical tools and experimental results recogmzed developed to assess the severe accident phenomena and sequences can only partly be used for accidents as
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| - De time period between initiation of a scenario happened at Chemobyl.
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| leading to a major core degradation and the melterough of Page IV.2 CHERNOBYL CONTERENCE.BY.COMPl!TER - Sept. 29 . Oct.17,1986 k
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| er TopicTwo: October 2 October'6:
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| g IMPLICATIONS FOR CONTAINMENTS-containments / intro'#1, from sysop,4704 chars, Fri Sep core for most events going beyond present design basis 26 14:43:46 1986 (Extremely improbable events such as fracture of the reactor pressure vessel need not be considered). Releases TITLE: Paper 1 of noble gases may be accepted if necessary to avoid more severe releases.
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| Implicanons for Containments '
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| - the Swedish Approach - De severe accident management strategies now being Lars Hoegberg ' implemented in Sweden to reach the "0.1 percent Swedish Nuclear PowerInspectorate ( mitigation targets" includes the following key elements:
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| (1) Prevention of early containment failure including The Chernobyl um.-ups again underlines that - protection of weak spots (e.g. penetrations) that may be damaged by direct attack of molten core prevention of accidents must remain a first priority in nuclear safety work. - hydrogen control
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| - means to handle single failure in the pressure i
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| Nevertheless, the discussion of the containment function will (and should be) intensified after Chernobyl. It is an j
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| i=" a- =- =t to say that the accidents at TMI and (2) Control of pressure and temperature in the Chernobyl, taken together, clearly demonstrate the contamment so as not to exceed design limits advantages of having a containment remaming intact after substantially in the first 10-24 hours. Evidently, use of l an accident involving severe core damage, compared to containment sprays and containment flooding will be key factors in controlling pressure, temperature and radioactive i
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| O having to build or rebuild a containment afterwards, under aerosols.
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| great time-pressure and in the middle of a severely contanunated environment.
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| (3) Attamment of a long term stable state for site Furthermore, Chernobyl underlines the social, economic recovery and clean-up, with the damaged core covered by and political consequences of long-term land usage water in a coolable geometry and in an intact depressurized containment. I restrictions and food and water control measures due to ground contamination. To avoid ground contamination involving extensive land usage restrictions (say more than The mingation strategies summanzed above originates i
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| a few tens of a sq. km.) source terms for radionuclides in a Swedish govemment and parliament decision from i such as lodme and cesium must typically be lower than 1981 and were reconfirmed in more detailed guidelines about 0.1 percent of core inventory. By and large this is a approved by the govemment in February,1986. 'Ihe r,s
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| [ stricter condition on the source term than that implied by y measures should be implemented by the end of i avoiding risks of early fatalides and radiation illness 1988. They include installation of filtered venting outside the plant. systems and various other measures of a design-specific nature.
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| In Sweden, a new safety philosophy with respect to the i In summary, the large R&D efforts in rece'nt years into containment function was formulated in the wake of the TMI accident. The key elemems in this safety p*I.c.why severe accident phenomena have provided us with the tools are the following: to analyze and improve containment performance in severe i , accidents. De analyses performed so far indicate that l (1) Even if preventive safety is high, the possibility of westem LWR containments in general have good basic an accident involving severe core damage must be capabilides to prevent large releases to the environment in recognized. case of a severe accident However, as existing contaiments have not been originally designed to cope (2) If an accident involving severe core damage occurs, with severe accidents, they may have weha s that releases to the environment of substances causing ground must be analyzed and addressed on a design-specific basis. i From a regulatory point of view, the social and economic contamination (such as iodine and cesium) should be kept below 0.1 percent of the inventory of a 1800 MW (th) consequences of land usage restrictions due to radioactive ground contamination must be thoroughly Ac"!swd when CHERNOBYI. CONFERENCE.BY-COMPtJTER - Sept.29 Oct.17,19a6
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| ! Page IV.1 w
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| ===== Westem LWR) at the Idaho National Engmeermg ,
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| contamments/ intro #5, from ehicken,1244 chars, Du -
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| Laboratory. In this test a PWR -type fuel rod melted and Oct 209:19:511986 the melt interacted explosively with the surroundmg water. The pressure rose to 34.6 MPa in 1.6 ms. The TfrLE: A comment on paper 3 resulting debris was made up oftmall, hollow, ruptured, A COMMENT ON PAPER 3 PREPARED BY spherical particles containing many voids an the particle S.C.SHOLLY wall (shell).
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| I WOULD LIKE TO COMMENT ON THE On the other hand, water was introduced into the TMI RELEASED ENERGY FOR THIS PURPOSE I core while large amounts of molten core materials were WOULD LIKE TO PRESENT THE FOLLOWING present without resulting in a steam explosion. A steam HANDCALCULATION. THE ENERGY Produced explosion occurred in RIA -ST -4 because finely RESULTS AFIER ALLIN A STEAM PRODUCTION. fragmented molten fuel particles were created and were THE MASS INVENTORY OF THE CORE IS ABOUT accelerated through water producmg a large surface area for 30M"3 OR ABOUT 23 TONS. IF ALL THE WATER heat transfer to the water. Here is strong evidence that .
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| IS EVAPORATED, A TOTAL OF ABOUT 40 000 hU vapor collapse and a chain -like fragmentation process IS NEEDED.TO MY KNOWLEDGE, ALL occurred. However, in ThG a vapor barrier to rapid heat EXPERIMENTS WITH A FUEIJWATER transfer likely formed of the melt crust when cooling INTERACTION HAS SHOWN A
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| * EFFICIENCY" OF water was introduced into the core during cycling of the B -
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| SEVERAL Percent OF THE TOTAL ENERGY loop coolant pump at 175 minutes. Similarly when RAPIDLY 1RANSFERRED TO THE FLUID. molten core materials broke through the crust in the core TAKEN THESE NUMBERS AN ENERGY OF flowed down into the lower plenum r.1 about 227 minutes, ABOUT 1000 TO SEVERAL THOUSAND hU IS relatively large streams were involved and the acceleration TRANSPORTED TO THE FLUID. HOWEVER, IT was that of gravity. As a consequence, vapor blanketing HAS BEEN STATED BY THE SOVJET EXPERTS slowed the cooling of this material when it contacted THAT ONLY A PART OF THE CORE HAS water and relative'y large particle sizes resulted. A 2 MPa PARTICIPATED IN THE POWER EXCURSION. THIS pretsure rise uompsiing to rapid steam generation was
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| ; WOULD REDUCE THE ENERGY RELEASED TO measured at 227 minutes.
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| THE FLUID FURTHER. In my opinion, it is very important to add as much E.HICKEN water as possible to a Westem -type LWR as soon as possible. I do not believe conditions to produce a steam explosion during a severe accident in a Western LWR are l containments /mtro #6, from 11each, $27 chars, Du Oct at alllikely to be encountered.
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| 2 16:24:39 1986 R.R.Hobbins This is a comment to message 4.
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| There are additional comments to message 4.
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| - . containments /mtro #8, from mryan,2775 chars, nu l The ' steam explosion' is an hypothesis put fonh by the Oct 216:55:091986 Soviets. We should establish if this is generally ag eed to.
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| Our calculations indicate a tube rupture would propogate TITLE: Query on status of steam explosion energy in their geometry. His would be exacerbated by high tube calculations temperature or pressure, resulting from the power Query to the authors of the Containment papers: Messrs.
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| cxcursion. What evidence is there for steam explosion vs. Hoegberg, Hicken and Sholly; and also to M. L'Homme silmultanous tube rupture? It is my understanding that of Source Terms:
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| calculations by others indicate three tubes is enough . Has anyone fine. tuned the calculations of thermal and todisassemble the reactor biological shield. Can anyone mechanical energy release in the initial steam explosion (s) confirm? that destroyed the reactor? My understanding of the Larry Leach situation so far is as follows:
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| Over 50,000 megajoules (megawatt-seconds) of thermal energy were released in the first few seconds of the containments /mtro # 7, from rhobbins,2010 chars, Du Chemobyl reactar accident, specialists at the IAEA have Oct 216:31:281986 calculated. De upper boundary of thermal energy release There is/are comment (s) on this message. could be something like 200,000 megajoules, the
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| - specialists believe, ahhough the minimum is much easier TITLE. Comment to paper #3 to calculate.
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| Steam explosions can take place at high pressure as He IAEA experts' conclusion, officials said, is based demonstrated by Reactivity Initiated Accident Scoping on the Soviet assumption-backed up by westem and Test 4 (RIA -ST 4) which was camed out at 6.4 MPa castem experimental data-that the Chemobyl fuel would initial system presstire with an energy insertion of about have disintegrated at energy loadings beginning with 300 350 call ^H/g (much higher than can be achieved in a calories per gmm. The Soviets have told the IAEA that CIIERNOBYL CONFERENCE.BY.COMPLTER - Sept. 29 Oct.17,1986 h, Page IV.4
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| s With regard to the impact of the Chemobyl accident on pressure and the presence of a large quantity of mohen fuel containment design and reactor safety, the author would . had been held to be prerequisites for a steam explosion
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| : e. like to put the items listed below up for discussion.
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| large enough to threaten containment integrity.
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| 'Ihe Chernobyl accident thus raises some interesting -
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| \ 1) Is it necessary to reassess power excursions for q='== about the conditions under which steam LWR's? ~ explosions can occur. For example, in a PWR station blackout accident sequence, if emergency coolant injection
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| : 2) Is it necessary to improu the asustance to operators is recovered while the core is "in extremis", should one to cope with unplanned scenario in order to prevent inject coolant (and perhaps risk a steam explosion), or -
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| accidents? attempt Ar+ u:on, permit the core to melt, and deal with the core debris after vessel failure? In addition, the
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| : 3) Should the evaluation be continued to study the large power surge at Chernobyl (due to the positive void possibility to mitigate the O=q=5 of accidents with coefficient) has been suggested as the cause for the steam core melt by .
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| explosion which destroyed the plant. Even if this is so, a) appropriate design provisions however, this is not the only means of causing a steam b) appropriate accident management actions? explosion. Consider, for example, the concept of
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| " accelerated meltdown" (suggested in the Sandia National
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| : 4) Have new and relevant physical phenomena be i mI=arnry in NUREG/CR-3440) under which conditions identified which are ofimportance for the nueument of sudden oxidation of cladding could lead to a ten gigawatt severe accidents in westem LWR's? thenna! power level due to reaction heat alone). The Chemobyl steam explosion suggests the desirability of a study of steam explosions in the context of a more containments / intro #4, from sysop,4633 chars, Wed Oct sizeable experimental facility and over a broader range o r 1 10 03:47 1986 simulated accident conditions.
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| The Chernobyl accident also raises a key question TTILE: Paper 3 concermng LWRs in which spent fuel is stored in the reactor buikhng. 'Ihis is applicable, for instance, to THE IMPLICA'I1ONS OF THE CHERNOBYL-4 BWRs with Mark I and Mark II containments in the U.S.
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| . ACCIDENT FOR NUCLEAR POWER PLANT Severe accidents - in which large amounts of hydrogen S CONTAINMENTS and/or carbon monoxide (ex-vessel) are generated - appear to have the potential for resulting, upon primary STEVEN C. SHOLLY '
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| containment failure, in a large deflagration or explosion in MHB TECHNICAL ASSOCIATES the secondary containment which poses the issue of I 1723 Hamilton Avenue, Suite K whether the spent fuel pool will survive (either due to loss San Jose, Cal. 95125 of physical integrity or loss of cooling systems). I.t is USA possible, for example, to hypothesize a radioligically (408) 266-2716 benign accident at a BWR Mark I plant which subsequently results in significant spent fuel pool accident
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| 'Ihe Chernobyl-4 nuclear power plant accident raises release due to hydrogen burmng in the secondary
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| , anew many phenomenological issues associated with containment.
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| severe accidents and containment tailure modes. It is by On the issue of containment at Chernobyl, it seems
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| . now widely understood that the key phenomenological obvious that a containment did exist. 'Ihe design basis for i
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| event was a rather large steam explosion. The magnitude the Ch rnobyl contamment (at least for the pump of the energy release has been estimated at from 200,MJ compartments) is similar to that for U.S. nuclear power to 320,000 MJ, and it may be some time before plants. A pressure suppression capability also existed, sufficiently detailed information can be compiled to permit although the specific capabilities of the suppression
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| - a more precise estimate. It should be observed, however, chamber at Chemobyl are not yet widely known. It also that the current range of estimates spans an energy release seems obvious, however, that there is an inherent which would pose either a minimal threat to a weakness in the Chemobyl design involving pressure tube contamment or a release which could not be stopped by integrity under severe accident conditions that renders the
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| ; any existing containment. Chemobyl containment less capable than a number of The Chernobyl steans e.xplosion happened under two other designs. It should be recogmzed, however, that i
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| circumstances of interest in other reactor designs. First, containments of the Mark I and Mark II BWR designs and the explosion occurred under high pressure (i.e., greater the PWR ice condenser design may not be significantly than ambient). Steam explosions were previously better in the long run.
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| h thought by many analysts to be suppressed at high Any contrary positions on these issues would make pressure. Second,if the Soviet analysis of the accident is for an interesting exchange, and I look forward to hearing correct, the steam explosion occurred without the fuel first from you.
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| l becoming molten. Prior to the acciden*, both low
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| 's CHERNOBYL CONFERENCE.BY.COMPtTTER- Sept.29. Oct.17,1986 Pase IV.3 US.
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| ~
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| My question to the last paragraph: SINGLE FAILURE OF PRESSURE SUPPRESSION Do you refer to addressing on a design. specific basis, or..
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| * SYSTEM. -
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| to stregthening existing containments to cope with severe 5) SOME INFORMATION ABOUT THE COST OF g accidents? IMPLEMENTATION. W Zsolt Revesz .
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| B. THE MEASURES DESCRIBED IN YOUR TALK WERE TAKEN PREVIOUSLY TO THE CHERNOBYL ACCIDENT. HAVE THEY BEEN CHANGED OR containments /mtro #13, from abrachet,647 chars, Fri INCREASED AS A CONSEQUENCE OF THE Oct 312:02:381986 ACCIDENT 7.THANK YOU FOR YOUR ATTENBON.
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| J.TAPIA TITLE: question and comment to paper 2 pr Hicken EMPRESARIOS AGRUPADOS, MADRID. SPAIN.
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| you say in your paper that there is a growing concensus that some mitigation measures can reduce risk.Could you indicate which mitigation measures are under consideration containments /mtro #16, from xjardi,328 chars, Fri Oct in FRG 7 Concerning your final items on safety our '3 12:27:38 1986 comments are the following This is a comment to message 4.
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| : 1. reassess power excursions for LWRs should be performed as a verification COMMENT ON PAPER #3 BY S.C.SHOLLY.
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| : 2. improve assistance to operators is already a lesson teamt from TMI. It induced alre.:dy for us development of WOULD YOU PLEASE DEVELOP YOUR safety panel, con:rol room rearrangement, revised EOPs STATEMENT: 'THE MARK I DESIGNS MAY NOT and U1 procedure, trainir.g for beyond.DBA accidents etc. BE SIGNIFICAN11Y BETTER IN THE LONG RUN".
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| IN THE PREVIOUS SENTENCE YOU REFERRED TO Brachet and Guimbail EDF THE INHERENT WEAKNESS OF THE CHERNOBYL CONTAINMENT DESIGN.
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| THANK YOU IN ADVANCE FOR YOUR containments /mtro #14, from abrachet,248 chars Fri ATTENTION.
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| Oct 312:16:151986 J.TAPIA. EA. MADRID, SPAIN.
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| TITLE: question from a BRACHET and h GUIMBAIL to s SHOLLY containments /mtro #17, from tmoore,689 chars, Fri Oct Your paper indicates the energy release as estimated to 3 16:31:18 1986 200 hU.320,000 hU. Could you indicate on which basis -
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| these two numbers have been calculated? TITLE: QUESTION FOR PANELISTS AND l PARTICIPANTS
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| ; A BRACHET and H GUIMBAIL -
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| l Can anyone c5nment on the points made by the Union of Concerned Scientists about the number of electrical and containments /mtro #15, from xjardi,909 chars, Fri Oct pipe penetrations in typical U.S. LWRs? UCS is makmg 3 12:19:07 1986 the point in the press that these penetrations are major This is a comment to message 1. potential leak points ira degraded core accidents, and that NRC records show numerous violations of rules COhBIENT ON CONTAINMENT INTRODUCITON pertammg to penetrations, open valves, doors, etc., that PAPER #1 BY LARS HOEGBERG. could become fission product release pathways. I bring up the points only for discussion.
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| A. WE WOULD LIKE TO KNOW SPECIFIC DESIGN Taylor Moore MODIFICATIONS IMPLEMENTED IN THE SWEDISH EPRI Joumal ,
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| CONTAINMENTS BASED ON THE POSTULATIONS Palo Alto, CA l OF SEVERE ACCIDENTS,IN PARTICULAR:
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| : 1) HAS THE FILTERED VENTING BEEN = =
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| IMPLEMENTED IN ALL SWEDISH PLANTS?. DO containmem/mtro #18, from tmoore.154 chars, Fri Oct YOU PLAN TO BACK FIT THIS REQUIREMENI7. 3 17:46:16 1986
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| : 2) TYPE OF PROTECTION OF CONTAINMENT i PENETRATION FROM MOLTEN CORE. HAS THEY TITLE: Addendum to last message.
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| L BEEN IMPLEMENTED?. My earlier question for conferecs about UCS allegations
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| ; 3)NEW EQUIPMENT TO CONTROL refers, as does the UCS criticisms, to containment HYDROGEN,IF ANY. penetrations.
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| : 4) TYPE OF MODIFICATION TO HANDLE
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| , Page IV.6 CIIERNOBYL CONFERENCE BY.CO31PLTER - Sept. 29. Oct.17,1986 30
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| they believe at least 30% of the core (which contamed a transfer and the generation of a steam spike (tube ~
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| total of 30 tonnes U) reached "more than" 300 cal /g.> pressunzanon).
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| The difficuhy in calculanng the energy released in by: ArielSharon '
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| ~ T - Chernobyl based on past accidents (for example, the NRX reactor accident in Canada or the SL-1 accident in the
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| . U.S.) or sg. J results, specialists say, is that conal =Wmtro #10, from lleach,245 chars, Fri Oct earber reactivity excursions were much more rapid than 3 01:16:13 1986 that at Chemobyl. This is a comment to message 7.
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| The IAEA calculanon of over 50,000 megajoules of energy released is not necessarily in conflict with the Dick, is there any evidence on Hydrogen generation in figure of 200 megajoules announced at the end of the those tests? I'm still not sold that the second explosion August 24-29 post-accident review meeting by Pierre was Hydrogen. It's not clear there was enough time for ifs Tanguy, the F= : .s leadmg one of the accident-review formation. At least, with the event timing the Soviets working groups. Tanguy was referring to the mechanical gave.
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| (not thermal) energy calculated to have been released in the Larry I.each Chernobylpower-excursion-plus-steam-explosion. De 200-megajoule figure, calculated by French experts -- - - - - - - - - - - - - - - -
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| admittedly in 10 minutes, was derived by ascertaining how containments / intro #11, from bruegger,1567 chars, Fri much kinetic energy would have been needed to lift the Oct 3 06:11:381986 1,004 tonne reactor upper plate and displace it, which was His is a comment to message 3.
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| . one of the observable effects of the explosion. He French in fact said that the energy was at least 200 Paper 3 states that "it seems obvious that a containment megajoules but could have been higher, and new did exist at Chernobyl. He implied contradiction between calculations reportedly put it at around 500 megajoules. the words "seems" and " obvious" makes me uneasy, but I De IAEA team has not attempted to calcuate mechanical
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| ~
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| shall not dwell on that. I am more concemed about the energy release from the accident; a specialist said that that proper use of the term 'contamment. For reactors in calculation was quite complicated, requiring detailed OECD Member countries, the containment can be defined consideration of factors such as mass and movement of to include both the pnmary and secondary enclosures as material.
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| well as the systems, components, physical phenomena, De -bM energy figure is the significant one for procsw which ensure that the risk posed to the
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| .Os determining whether the containment of a given reactor environment is acceptably small should radioactive would have resisted the big bang of Chernobyl. matenals escape from the cooling system of the reactor; Does anyone have more up-to-date data? Best regards the containment must also assure the proper operation of from Vienna, Ann Maclachlan systerns imponant to safety as long as postulated accident conditions require. This de5nition hardly fits the Chernobyl 'containmenf. I do not think the Soviets have containments / intro #9, from asharon,874 chars, nu published detailed plans of RBMK containment systems Oct 218:58:421986 but what we have seen so far is probably better represented This is a comment to message 7.
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| by the words ' partial containment or, perhaps, by a mix here are additional comments to message 7.
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| cf contamment and confinement (considering the large voame of the reactor hall). I therefore submit it would be TffLE : STEAM EXPLOSIONS better to stop using the term ' containment in the context When using the term " steam explosion" in context with of RBMK reactors without proper qualification, in order to j western LWR's accidents the following stages must exist aboid confusion and misunderstanding and in order to j- A. Molten fuel must be premixed with coolant seperated
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| * avoid creatmg artificial problems for Westem-type
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| ( _ by vapor fdm.
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| containments. For RBMKs I suggest using the phrase l B. De vapor film colapses due to some trigger (external ' partial containment (although, very likely, the term
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| ! or intemal)
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| 'pseudocontainment would be more accurate). Any views C. The local interaction er2hre< to a detonation wave. on this ?
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| D. De detonation wave propagates through the J.ROYEN fuel / coolant mixture.
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| OECD-NUCLEAR ENERGY AGENCY (NEA)
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| , PARIS l For such fuel / coolant interations molten fuel and t
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| pressure limitations are typically required. In the - - - - - - - - - - -
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| Chernobyl accident, however, fuel / coolant interactions containments /mtro #12, from zrevesz,176 chars, Fri Oct
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| >' c vi 'o' >'r di'r < - ca i ta ti O 'pp*licable a to LWR's that can not undergoo< 311:o4:39 1986 a power This is a comment to message 1.
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| excursion. In Chemobyl fuel particles of few microns There are additional comments to message 1.
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| were mixed with the coolant allowing for rapid heat CHERNOBYL CONFERENCE.BY.COMPtTTER- Sept.29 Oct.17,1986 Page IV 5 l
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| l
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| reactors by the existing safety systems.
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| Does anyone know more details? --- containments / intro #27. from mberman,10465 chars, Best regards Wed Oct 8 13:11:14 1986 g
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| Enno Hicken W
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| A DISCUSSION OF S'1 TAM 1XPLOSIONS AND
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| . _ _ _ _ _ . _ . . . . . . - - - - - COMMENTS ON RELATED PAPERS containments /mtro #25, from mryan,1102 chars, Mon Oct 611:02:211986 TITLE: A DISCUSSION OF STEAM EXPLOSIONS AND COMMENTS ON RELATED PAPERS TITLE: Comment on Questions from J. Tapia, message 4,6,7,8,9,10,21,26, etc.
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| 15 From Lars Hoegberg, Swedish Nuclear Power .
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| Marshall Berman Irapectorate, Stockholm Sandia NationalI.aboratories Replies to questions by J. Tapia Madrid,' Spain My knowledge of the Chemobyl accident comes A1: Systems for filter venting will be backfitted at all pnmarily from articles in the lay and technical press, and Swedish reactors by the end of 1988. - from References 1-3. Dere are many aspects of the t
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| accident that seem uncertain and speculative, especially the A2: De principle protection of penetrations will be chronology of the last few seconds before the " explosion."
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| provided by flooding the lower dry-well floor in some ne prevailing descriptions of these seconds are quite BWRs. Systems for automatic or manual triggering of inconsistent (e.g. see 1, p. 21; 2; 3]. Several assumptions such flooding in case of core overheat have been installed. pervade the discussions at this conference: He fuel was In addition penetration will be fitted with special thermal not molten at the time of the steam explosion; the solid shields, the design of which has not been fbh-A fuel was prefragmented into "small' pieces before it contacted the " coolant;" the " coolant" was predominantly A3: Our BWRs are inerted; otr PWRs have large dry steam. It is not clear to me which, if any, of these containments. Residual hydrogen risks will be snalyzed. assumptions are true. De following discussion provides my speculations conceming possible scenarios at A4: A free-blowing safety valve (rupture disk) with high reliability isolation valves, reclosing after the pressure Chemobyl, based pnmarily on the computer. generated parameter histories prepared by the Soviets and my own g
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| spike. cxtensive experience in this field.
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| A5: Present, very tentativa post estimates are in the High AmbientPressure range $3- to SS- million per reactor. No additional cutage ne modelling histories show that the ambient is envisaged. ,
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| pressure was at least 90 bars, and could have been much
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| / higher. Steve Sholly (message 4) is correct in stating that B: De Chemobyl accident has resulted in no major if there was a steam explosion at Chernobyl,it would technical change in the program. De impleme.ntation has contradict what some experts have claimed - that such been accelerated, where possible. events are incredible at such high pressures The RIA-ST-4 accident discussed by R. Hobbins (message 7) lends even more credence to the possibility of steam explosions containments /mtro #26, from mhutcherson,474 chars, at high ambient pressure. He states that an energy Mon Oct 6 13:30:27 1986 insertion of 350 cal /g " melted" a fuel rod "and the melt This is a comment to'rnessage 4. interacted explosively with the water." His description of the post-explosion debris is very similar to debris we have TO: Distribution observed in some of our experiments [4]. His FROM: Michael N. Hutcherson experiment also leads me to question the Soviet statement Fauske and Associates that the fuel did not melt, even though their calculated Burt Ridge, Elinois 60521 energy insertions of 300 cal /g (mean value? +/- how USA much?) could easily have been sufficient to melt much of RE: Comments to Steven C. Sholly's Paper (No. 3) the fuel and the cladding, considering the power DATE: 6 October 1986 ~ asymmetries.
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| I would like to respond to this p1per, and since I am resporyling to this issue (steam explosions) in also the Coolant Quality
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| ' source terms'section of this conference, I wi!! register my It is difficult to read the P (volumetric steam quality,0-responce in the latter region. 1.2%) and O (mass steam quality 0 6%) curves in the Bank you, plots of the computer simulation. However, the upper The end.
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| CHERNOBYL CONFTRENCE.BY. COMP 1TTER - Sept. 29 Oct.17,1986 g Page IVi8
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| .1, .
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| explosion at ChernobyL From what I understand, the contamments/mtro #19, from rhahhl=. 404 chars, Fri presence of liquid water is required to produce a steam Oct 318:25:191986 explosion of the type we observed in RIA-ST-4.
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| However, the production of voids (to quite high fractions?)
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| O Tr1t:a t nc re air-sT-4 cai c ai - 8- - -aary element in the power excursion at
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| #7) Chemobyl. Thus, it is not clear to me that conditions to M.S.El Genk, R.R.Hobbins, and P.E.MehM " generate a steam explosion by molten fuel coolant Molten Fuel Coolant Interaction Dunng A Reactivity interaction were present at ChernobyL Initiated Accident Expenment " Nuclear Engmeering and Dick Hobbins Design 66 (1981) 247-267.
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| M.S.El Genk, R.R.Hobbes, and P.E.MehM "
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| W.g dii of Molten Debris Durmg A Molten Fuel contamments/mtro #22, from lleach,369 chars, Sun Oct Coolant Interaction," J. of Nuclear Matenals 113 (1983) 5 23:29:27 1986 101-117. ,
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| This is a comment to message 21.
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| Dick containments /mtro #20, from mgoldman,1130 chars, Check Don Fletchers calculations. Although he's not Sat Oct 4 11:22:19 1986 getting the same time to " lift off', he is getting a large power surge and shutting the inlet check valves like they TITLE: comment on papers 1 & 2 did. I think this happens at less than 50% core average it seems more and more apparent that the limiting void fraction. That is, there's still plenty of water. rd be factors for contamment performance design need to focus interested in knowing if that's true I haven't seen details on the prevennon of the escape of fission products which yet. Larry can contaminate land and facilities and deny their use.
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| TMI clearly indicated that core damage prevennon systems are more suong'y justified in terms of protecting the containments / intro #23, from lleach,245 chars, Sun Oct owner's investment (an economic perspective) than by the 5 23:33:26 1986 need to provide public health and safety protection. So also it would seem to me that, given the relatively modest TTILE: Contamment Capability -
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| L- (for a " disaster") and likely impr.@le costs to public I keep getting asked if US (or all Western) containments i health, the Chemobyl experience confirms the purely could have withstood the explosion which occured at
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| ;' economic jusuficadon for the modification of containment Chemobyl. Can we get answers for each containment systems to prevent the release of those fission products type, ie. dry, ice condenser, suppression, and CANDU?
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| such as cesium and iodine with capabilities for significant residualcontammanon.
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| containments /mtro #24, from ehicken,1979 chars, Mon In this regard, the Swedish movement toward filtered, Oct 610:16:391986 vented containtnents (parucularly if the cost is as modest t
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| as suggested in the first paper) is in the right direction, TITLE: Responce to cont. intro 11
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| ! and deserves auention by the rest of the western nuclear Response to intr # 11 i community.
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| Dearjacques J agree with your concem about the proper use of the term ' containment"Ihe Senior Group of M Goldman, NUS x Experts on Severe Acidents has defined: The
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| " containment" is astructural envelop which completely l surrounds the reactor system and is designed to hold the
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| ; contairiments/ir.tro #21, from rhobbins, 866 chars, Sat releases from design basis accidents with little or no
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| .Oct 419:06:431986 release to the invironment. The term is used in its broader l There is/are comment (s) on this message. ,
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| sense to include associated leakage paths and buildings which contain the releases of severe accidents. Because the
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| { TITLE: Comment to message 10 DBA is a failure of 'one' pipe,the RBMK reactors are j Lany,in test RIA ST 4 there was some oxidation cf capable to avoid a release to the environment ,because a l = the fuel rod debris and the zircaloy shroud which was rupture of a pressure tube between the upper core schield
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| ; heated by the impingement of molten debris.
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| and the inlet of the separators can be managed by the
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| : I did a very rough calculation for the Chemobyl reactor ventilation system. We were told that all compartements which indicates that at 2200 K a flammable quantity of with pipes containing pnmary circuit fluid are under a Oguantity in about 3 s.rNhydrogen could be produced in aboutI feel slight underpressure. I s that andthean mainexplosive question is the definition of a 'DBA'. It is my feeling that e.g. most I have one difficulty with the hypothesis of a steam sequences with an ATWS cannot be managed in RBMK CHERNOBYL CONFERENCE.BY COMPl?TER - Sept.29 . Oct.17,19s6 Pase IV 7 .g A
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| No. 6083,4- 10 September 1986, basis for the containment.
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| : 4. L S. Nelson and P. M. Duda, " Steam Explosion , ,
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| Does anyone know whether such calculations have Experiments with Single Drops of Iron Oxide Melted with , been made for other containment designs 7- Can anyone a CO2 Laser," SAND 81- 1346, NUREG/CR 2295, September 1981.
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| , identify the manmum force an LWR is expected to generate-and/or the force the contamment is expected to h
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| : 5. M. Epstein, H. K. Fauske, " Steam Film withstand?
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| Instability and tne Mixmg of Core-Melt Jets and Water" Thanks for any assistance. Ann Meinchhn ANS Proceedmgs of 1985 Nanonal Heat Transfer Conference, Aug.4-7,1985, Denverg Co.
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| : 6. R. P. Feynman, Contribution to the President's containments /mtro #30, from 11each,940 chars, Thu Oct Commission Investigating the Challenger Accident,1986. 9 13:20:19 1986
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| : 7. M. Berman, Section E 1 in " Steam Explosion Review Group Report: A Review of the Current TITLE: AccidentSequence Understanding of the Potential for Contair> ment Failure It would have been nice to have a conference on the Ansmg from In-Vessel Steam Explosions," NUREG- .
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| accident sequence. This looks like the best place of what's 1116, February 1985. available.
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| : 8. M. F. Young, M. Berman, L T. Pong, " Hydrogen Generation During Fuel-Coolant Interactions," presented As I reported wearlier, we have been unable to duplicate at the American Chemical Society Meeting, Anaheim, the very rapid power increase reported in the Russian Califomia, Sep. 12,1986. simulation. It is interesting to note it occurs right after the SCRAM was pushed.
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| We now may know why.
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| containments / intro #28, from mryan,1058 chars, Wed I have been told some people at PNL have observed that Oct 813:45:57 1986 the graphite control rod followers are not full length.
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| That is, at the full withdrawn position, there will be water TITLE: Containment issues from Source Terms in the lowest part of the channel. Thus, the initial effect of a SCRAM from full withdrawn position, particularly To all participants:In the source terms section of this with a bottom peaked flux profile, would be to cause a conference, there were several issues raised relevant to reactivity insertion. This could be the " trigger" we have containments. Dr. Alain L'Homme noted there is been looking for. We will follow this up, agreement that a sequence of events precisely like .
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| Chemobyl's could not occur in an LWR. But he asked Does anyone have any informadonon this?
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| whether we are equally certam there is no other sequence that would give LWRs an acgident of similar It will be ironic if the act of pushing the SCRAM is characteristics: fast and catastrophic, with essentially no what really tdggered the event.
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| warnmg time. So:
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| 1.Is there certamty about the fastest, most powerful accident LWR containments could confront? What is it? Is containments /mtro #31, from bmann,369 chars, Thu it part of containments' design bases?
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| Oct 913:21:191986 2 There was some uncertainty expressed in the source , There is/are comment (s) on this message.
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| term section about the exact sequence at Chemobyl and ----
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| the role played by a steam explosion. There has been TITLE: Tube Failure Propagation much discussion in U.S. source term research over the On either this conference or the Source Term conference, role steam explosions might (or might not) play. Is this reference was made to studies which indicated that the uncertamty accounted for in setting containments design failure of one tube in the RBMK design could lead to bases?
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| other tube failures due to the mechanical transfer of energy I'd appreciate information from anyone on these through the graphite. I would like to get more' questions. Margaret Ryan information on that if possible.
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| Brian Mann, Virginia Power containments /mtro #29, from nuyan,551 chars, Wed i i i Oct 813:46:481986 containments /mtro #32, from halbrecht,1151 chars, Fri Oct 1006:02:21 1986 TITLE: Containment design bases This is a comment to message 4 To all panicipants: For the Super-Phenix breeder reactor, calculations were made of the maumum explosive force O
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| In the Westem LWR safety research, large violent steam to which the an accident might subject the containment -it explosions are discussed in the frame of scenarios where was 800 megajoules. This was then made the design masses of molten fuel may drop coherently into a water Page IV.10, CHERNOBYL CONFERENCE.BY COMPITTER - Sept. 29. Oct.17,1986
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| ~. ,
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| 1 l
| |
| limits cf the ranges of these quantities imply that a great Ariel Sharon (message 9) has provuled his dermition !
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| deal of liquid waser could have been present in some fuel of sseam explomons, which contains a plethora of j channels at the time of the " steam explossort " If one modifiers. I prefer my own definition ~given in Ref. 7: "A I
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| - takes into account asymmetnes in the fuel channels and steam explosion can be simp,1y defined as a boiling the posential errors in the computer simulation, I don't see process rapid enough to generate shock waves." Many how a large amount of liquid water can be precluded. ne people have profferred complex definitions of steam computer histories also show that the main circulation explosions. I think that such definitions tend to cloud the water flow began to increase dunng the last two seconds safety issues, and introduce artificial barners to before the explosion. Derefore, it is possible (or likely) knowledge. Our pnmary concern is to prevent damage to that some channels were beginning to refill with water. the reactor. Arnficially restnctive definitions should not Molten fuel and clad could have fallen into these " puddles" be used to create logical and semantic barriers to
| |
| - of water. An explosion in one channel would have set off understanding the Chemobyl explosion and assessing its a chain reaction of explosions in adjacent channels, relevance to Western reactors.
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| resuking in a coherent explosion.
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| L Leach (message 10) questions whether there was In summation, I believe that melting of the fuel and sufficient time to generate hydrogen for the second clad, subsequent contact of these materials with liquid explosion. We recently presented a paper [8] that included water, and a resulting steam explosion is a credible models for predicting the rates and amounts of hydrogen
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| ' sequence c,f events. that could be generated during steam explosions. Two different models were used; one model assumed that R. Hobbins (message 7) says that large amounts of molten metal reacted with a steam environment, and the molten core matenals contacted water at TM1 without an other with an environment composed primarily of liquid explosion. He notes, however, that a 2 MPa pressure water. In both cases, large quantities of hydrogen were ,
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| spike was observed (far away from the vessel lower predicted to be generated on the time scale of the steam I plenum region) above a background pressure of 10 MPa. explosion,0.5 to 5 ms.
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| I submit that such a spike could easily have been created by one or more steam explosions, or by a highly energetic R. Hobbins (message 7) feels that one should add as fuel- coolant interaction. Furthermore, the supposition much water as possible to a Western LWR as soon as that "relatively large streams were involved" resulting in possible. I will address this comment in my paper in the Accident Management Cortference.
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| O s"relatively large panicle sizes"is,in fact,just upposition. Current experiments at Sandia indicate that streams of diameters comparable to the diameters of the In summary, I believe the following sequence of holes in the structural plates could indeed break up into events at Chernobyl is a plausible scenario: De
| |
| . small panicles. Ref. 5 presented a calculational model of reactivity transient leads to melting of some of the jet breakup. De authors stated that "a 10-cm diameterjet zirconium and fuel. De molten material is expelled into of core. melt rnatenal is predicted to disintegrate after the fuel channel where it contacts water, or it falls into falling only 27 cm through water." Hole diameters for the water residing at the bottom of the channel. One of the various TMI support and grid plates ranged from about 8 channels spontaneously triggers a steam explosion, and to 16 cm. the generated shock triggers a large number of other channels to explode. De steam explosions produce large
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| ! We have a great deal of experience with steam quantities of steam and hydrogen which lift off the reactor i explosions involving melt masses ranging from 50 mg to roof. De steam and hydrogen mix with the ambient air i
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| 50 kg. We have observed explosions for fuel falling under initially in a mixture too rich to explode. As the
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| ; gravity into coolant and for coolant pounng onto hydrogen-steam-air. hot fuel / metal spreads into the i quiescent molten pools. At large scale, occurrence of building, it generates more hydrogen from metal-steam
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| ( explosions sometimes appears random. His variability reactions, and mixes with more air until it finally reaches
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| ! has been observed extensively both for controlled a detonable concentration. A detonation is then initiated i experiments and industrial accid:nts. We believe that this by the hot fuel and hot oxidizing cladding. Witnesses i ,
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| is primarily due to a randomness in the availability of a would hear these events as one explosion after another, '
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| trigger, We have also observed fuel-coolant interactions just as the Soviets have reponed.
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| ! with a wide range of intensities, from benign boiling, to i mild explosions, to extremely viol:nt explosions. To REFERENCES conclude that Western LWRs are not minerable to steam 1. USSR State Committee on the Utilization of explosions based on the " presumed
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| * absence of an Atomic Energy,"The Accident at the Chemobyl Nuclear i explosion at TMI is to make a grave error. Richard Power Plant and Its Consequences," Draft, August 1986.
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| O Ffactr that - theiafirst(6): ws vi ri"= a si re rette the shot got off safely is little comfort for
| |
| : 2. caer e87 i: n seviet neve<>." " cie r s --
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| Special Repert, Sept. 11,1986.
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| l the next." 3. " Chronology of a Catastrophe," Nature, Vol. 323,
| |
| ... curasoart, costrarscr.sv.courtrrra s.pe.29. oci.17,19s6 P.s.iw9 k.
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| 1 _._
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| combination with rapid vapour generation is, as far as I qualification of components and operators. However I know, a new and previously unobserved phenomenon. The believe that design change and mitigation measures should explanation of the event as a steam explosion appears capable of accounting for the pressure tube rupture and be investigated in order to at least we know how it works g subsequent explosion, and there does not seem to be a and to what extent it is effective and why other countries W are going to implement. I support this activity.
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| need to postulate a solid fuel fragmentation / vapour Item 4), I believe that most of physical phenomena generation mechnism to explain events. Having said this, can be explainable from our knowledge on severe accident.
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| solid fuel fragmentation effects do descreve further Only concem I have now is chemical forms of fission investigation. products released to the environment.
| |
| Steven Hall K. Soda / JAERI/Tokai Safety and Reliability Directorate, UKAEA.
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| containments /mtro #40, from shall,68 chars, Wed Oct containments / intro #37, from 11each,63 chars, Tue Oct 15 11:19:23 1986 14 17:05:52 1986 This is a comment to message 37.
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| "Ihis is a,, comment to message 34.
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| To a layman, anything that goes ' bang'is an explosion.
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| Would a'dellagration be reported by wimesses as an Steven Hall explosion?
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| containments /mtro #41, from psviatoslavskyx,647 containments /mtro #38, chars, Wed Oct 1511:41:511986 This is a comment to message 35.
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| Withdrawn -
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| I believe there is a major difference between the Chemobyl containment and westem LWR containments containments /mtro #39, from ksoda,2241 chars, Tue that has been overicoked in this conference. Not only Oct 14 21:03:281986 This is a comment to message 38.
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| must westem LWR containments be capable of withstandmg LOCA loads, they are capable of g
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| withstanding outside loads (i.e. missles caused by COMMENTS TO PAPER #3 BY DR. HICKEN. tornadoes, aircraft crashes). From the diagrams of the I would like to see more discussions on the items Dr. Chemobyl reactor, it appears as if the reactor hall is not Hicken raised in his paper in terms ofitems 1) through 4). designed to withstand outside loads. Is it so unreasonable Item 1) referred to a consideration of reassessment of to postulate a senerio in which a tornado could cause the power excursion of a light water reactor. It is our concern refueling machine to collapse on top of the reactor?
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| that multiple rod ejection could be excluded from safety Pete Sviatoslavsky consideration based on some justification. WPSC l A single rod ejection is currently considered in the
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| ; safety analysis for the licensing purposes in Japan. .
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| However, a multiple rod ejection is not the licensing containmentsimtro #42, from mberman,3145 chars, purposes in Japan. However RIA intiated from multiple Thu Oct 1611:23:471986 rod ejection is not considered. I believe that we need to - ---
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| justify this by either probabilistic approach or design to - TITLE: Comments on Hydrogen Explosion prevent such occurrence. In that respect,It is necessary to TTILE: Comments on the Nature of the Chemobyl reassess power excursions for LWR's as well. Second Explosion Item 2) asked necessity to improve the assistance to operators. It is not easy to prepare for unplanned scenario Marshall Berman at this time by some of hardware or computer. If operators are given enough time to cope with an accident I agree with most of Steve Hall's comments in they should be able to manage the accident by reasonable messages 34 and 36. My description of the xcident manner. Only requirements they should be able to sequence (message 27) assumes that a steam explosion led manage the accident by reasonable manner. Only to the destruction of the rextor, but that a hydrogen requirement may be well-trained and well-qualified explosion occurred in the room above and lifted off the operators to cope with unplanned scenario. Perhaps we roof of the building. However,I believe that the second need a standard qualification for operators in the world. explosion was a detonation (or highly accelerated flame),
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| For Item 3), it is the Japanese regulatory position that and not an ordinary deflagration.
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| no additional safety measures are necessary. A severe accident must be prevented by proper maintenance and ,
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| I do not believe that the geometry above the reactor Page IV.t2, CHERNOBYL CONFERENCE.BY. COMPT,TER - Sept. 29. Oct.17,1986
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| | |
| would make c detonanon "vumally impossible to the conference. I am now able to respond to the numerous achieve." In fact,I think that a detonation could be very comme ..s and papers in the conference, and would likely under the cin:umstances for the following reasons: appaciate hearmg from anyone still interested either via p) the conference or by wf-4Aelephone.
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| ( = De hydrogen-air sensitive; a great dealmixture could of turbulence have would have been locally very ~
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| accompanied the'a===8da= of steam and hydrogen from RESPONSE TO PAPER 1 BY LARS HOEGBERG the reactor, and the mixing with air would be fast and STEVEN SHOLLY, MHB TECHNICAL turbulent: the very hot cose matenals would have ASSOCIA'IES provided multiple strong ignition sources for a "nearly" '
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| direct initianon of detonation; the turbulence generated in Dr. Hoegberg is quite correct that only limited source -
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| the vicinity of the fuel loading machine and the adjacent terms can be accepted if extensive ground contamination is t walls could have caused a rapid transition to detonation to be avoided. I would observe, however, that iodme '
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| [1]. >
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| releases would impose such restrictions only for the short term. Of greater concern are cesium and, if released in I believe that it is a mistake to assume that strong - even single percent quantities, the lanthanide species.
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| ; shock waves are a necessary prerequisite for initiation of detonanon. If the burnmg rate of the gases is'sufficiently RESPONSE TO PAPER 2 BY ENNO F. HICKEN
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| : intense, a detonation can be induced. Various methods for STEVEN C. SHOLLY, MHB TECHNICAL initiating detonanons are discussed in Reference 1. ASSOCIA'IES f
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| Deflagranons usually do not sound like explosions. Dr. Hicken states that the time penod between The burn at TMI was described by people in the control accident initiation and vessel failure is "usually more than room as "a thump, a bump, a whoomp. " [2]. I to 2 hours". I have observed that it is frequently the Expenmenters at Sandia have described the sound of a case in severe acculent calculanons undertaken with the j deflagranon as a whoosh or whoomph, sometimes MARCH code that the time penod between accident drawing colorful, but R-rated, comparisons to the bodily 4
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| initiation and vessel failure is usually of the order of 1 to functions oflarge mammals.
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| l 2 hours. It should also be observed that for containment i
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| bypass scenarios such as Event V and steam generator
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| ; A constant-volume deflagration involves a spaually tube rupture (in PWRs), this time period it largely
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| ; uniform increase in pressure. If the " explosion" broke the meaningless. Rather, the time period of interest for i fuel-loadmg machine,it would mean that shock waves had counter measures is the time from accident initiation and been developed. Furthermore, the thermal loads induced by the start of core degradauon, a rather short period of time.
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| , detonations would be considerably smaller than Dese are also the accident scenanos which are likely to deflagration loads. If there was little or no scorching of contribute substantially to public risk.
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| the side walls,it would be funher evidence of a detonation Dr. Hicken also states that if early containment rather than a deflagration. failure can be avoided, several hours or even days are
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| ! available before containment failure, and that this provides REFERENCES time for accident management actions. I would add that
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| : 1. M. Berman, "A Critical Review of Recent Large- such actions should be well considered before hand, Scale Experiments on Hydrogen-Air Detonations, Nuc. otherwise there is a non-trivial risk of taking inappropriate I Sci. and Eng. 93, pp. 321-347,1986. '
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| actions that could lead to containment failure at an earlier
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| : 2. M. Rogovin, Din:ctor, Vol.1, Three Mile Island, A time. In addition, for PWRs, there is a tendency to lose Report to the Commissioners and to the Public, Nuclear steam inerting over a period of hours, thus presenting the Regulatory Commission Special Inquiry Group,1980. possibility for a rather large hydrogen burn. Of course, the source term at such late times may be limited, but containment failure is nonetheless quite possible.
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| containments /mtro #43, from mbennan,3035 chars, Thu Oct 16 23:34:56 1986 -
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| COMMENT ON R. HOBBINS COMMENT #7 STEVEN SHOLLY, MHB TECHNICAL Repeat of #42 ASSOCIATES I agree that it has been shown experimentally that containments /mtro #44, from ssholly,14892 chars, Fri steam explosions can occur under high pressure. My Oct 1711:43:141986 point was that many severe accident analysts appear rather thoroughly convinced that the likelihood of this occurring "ITII.E:
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| under severe accident conditions is vanishingly small. Of ;
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| NOTE FROM STEVEN C. SHOLLY, MHB course,I disagree with this conclusion, and believe that TECHNICAL ASSOCIATES I experiments at Sandia National Laboratories and elsewhere regret that illness has prevented my timely participation in speak eloquently to the matter.
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| , CHERNOBYI. CONFERENCE BY COMPLTTER- Sept.29. Oct.17,1986 Pese IV 13 ,
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| TITLE: Containment from E. Hicken all properties have not been determined and characterized.
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| I like to rbspond to the question if the second explosion The " free contacting" mode of steam explosions g was a power excursion or a hydrogen detonation. might be dermed as consisting of the five steps proposed W by Mr. Hutcherson. However, in my discussion in
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| : 1) The upper core plate is located now in a vertical Containment Conference message 27 I described a position. During its movement from the horizontal to the scenario in which all five steps do occur. Fuel melt is vertical position the jet coming out of the reactor space ejected and falls into water in the bottom of the channel must have been redirected. This must have cause a lot of ("contamed interaction zone"), coarsely fragments before, damage to the building. during, or after its contact with the water, undergoes a spontaneous " triggering," followed by " fine
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| : 2) During the week following the Vienna Conference I fragmentation" and " expansion of the coolant vapor."
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| asked Dr. Kalogin about the position of the graphite blocks. He told me that the blocks were totally dislocated. In addition to the free centact mode, other " modes" of We came to the assumption that something must have steam explosions have been experimentally observed, and happened in the lower part of the core after the upper core are believed to have been involved in some major plate lifted. I believe that a hydrogen detonation can not industrial accidents [c.g., see 4]. Steam explosions have dislocate the graphite blocks in the lower part of the core. been observed for fuel coolant configurations which are Berefore, I believe that the second explosion was mainly initially separated or stratified [5,6]; i.e., the coarse a power excursion with possibly an additional hydrogen fragmentation does not arise from the active injection of bum. one liquid into another, instead, the two liquids begin to spontaneously mix themselves. His explosive self-I like to respond to remark Nr.13 from Mr. Abrachet. mixing ele until an energetic steam explosion is I stated that there is growing consensus that some spontaneously triggered. Another example of explosive mitigation measures can reduce risk. "D''- tatement is self-mixing involves the occurrence of a small steam based on studies and decisions in seve iuntries, e.g. explosion which produces an efficient coarse mixture in Sweden, France, FRG, etc. In the FRG . have installed which a larger explosion subsequently occurs (7]. This devices in two powcr plants to limit or decrease the bootstrapping effect is commonly observed in gas phase pressure in a PWR containment. This measure would allow to avoid an overpressure failure. In one case the combustion and leads to flame acceleration and sometimes to transition to detonation.
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| g decision was based on the assessment that a leak-before-break could not be guaranteed. In the FRG and - to my On the other hand, many experiments have also shown knowledge - also in other countries efforts are underway to ' hat if the fuel is too fragmented or dispersed prior to or further study mitigation measures. during its entry into the water, then explosions usaally do not occur [811]. Distinguishing between legitimate and illegitimate steam explosions can be of value only if one containments /mtro #48, from mberman,15980 chars, can show that illegidmate steam explosions are of no Mon Oct 2014:12:311986 concem in reactor safety. His has not been shown.
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| TITLE: Chernobyl " Steam Explosion" ,, De published literature also contains definitions of physical vapor explosions which encompass both the TITLE: Chemobyl " Steam Explosion" - Comments on violent mixing of two liquids at different temperatures and Message 53 by M. N. Hutcherson the rapid mixing of a finely divided hot solid material with
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| > a much cooler liquid (2]. He definition that I provided Marshall Berman dealt with the propagation of a steam explosion, not the Sandia National Laboratories damage mechanism. If the collapse of the vapor fdm about a single fuel particle does not produce vapor
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| . DEFINITION OF " STEAM EXPLOSION" sufficiently fast to generate shock waves, then the film co!! apse will be an isolated event, unable to influence the Although the occurrences of steam explosions have neighboring fuel particles and their surrounding vapor been noted for centuries [1], a universally accepted blankets - there will be no steam explosion. However, if definition does not exist. Phenomena essentially the same pressure waves are generated by the fragmentation of a as steam explosions have been called " physical vapor single particle which are srong enough to cause the fine explosions" (2], " rapid phase transitions" (RPT), fragmentation of more than one additional fuel particle,
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| " explosive boiling," or "fue!<oolant interactions" [3]. then a steam explosion can be propagated through the However, the scientific definition of a phenomenon should mixture. This process is analogous to the chain reaction not te so comprehensive that all the properties of that required for fission. The PARTITION of the energy phenomenon are embedded in its definition. This is released from a steam explosion is also analogous to an especially true of poorly understood phenomena for which underwater HE (e.g. TNT) explosion. Part of the energy is Page IV.16 Cl!ERNOBYL CONFERENCE.BY.COMPtTTER - Sept. 29 Oct.17,1986 hO
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| I RESPONSE TO ACCIDElfl' MANAGEMENT PAPER In addinon,I agree with the vanous sesponders to this BY M. BERMAN comment that the key is considering one's options and STEVEN C. SHOLLY, MHB TECHNICAL capabilities before the accident happent.
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| ASSOCIATES k-m) "Ihere is a very instructive' report available from the
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| - Regarding your comments on evacuanon, much work U.S. Federal E.T-s eucy Management Agency concerning has been done on when and why to initiate evacuanon. In how emergency response dcwloped during the TMI my opmion, far too much auention has been paid to accident. I would 0==4 report to the auention of evacuation planning, per se, and emergency response - the interested parties: " Evacuation Planning in the TMI -
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| lauer including evacuation as well as sheltering, Accident," prepared for FEMA by Human Sciences respiratory protection. I am most concemed that public Research,Inc., WilEam W. Chenault, Principal officials could be persuaded by this unfommate focus on Investigator, evacuation - to the exclusion of other means of protection -
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| - that in the event of another severe accident in the U.S.
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| containments / intro MS, from jmmnwk,1838 chars, Fri there will be almo::t a knee-jerk reaction to recommend an early evacuanon. Should an early contamment failure or Oct 1713:15:461986 bypass occur, this may be the worst thing to tio. It may make ccish Aly more sense to shelter and relocate TITLE: Comment on message M4 from ssholly following plume passage. Your comment about evacuation being the knee jerk reaction to a NPP accident is absolutely correct. In the Is anyone aware of any recent work on comparative US, the responsible authority for initiating public action benefits of various emergency response schemes? It is the governor of the state or his designee. While either seems to me that some thoroughly credible work in this will be receiving advice from a host of specialists (or area is needed bom to infonn emergency response officials other "expeits"), experience shows that there is great of the situation and to give the public some reason to reluctance on the part of such elected or appointed officials listen to emergency broadcasts during reactor accidents. la to heed such advice if it runs contrary to their preconceived the absence of such a program. I am concerned that the notions, or gut reactions, or even political exigencies.
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| response of the public will be to evacuate at the first hint Sheltering and respiratory protection are viewed as "doing
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| . f real problems. . noming", while evacuation is viewed as an action which shows leadership. In New York, the head of the Disaster O Regarding your comments on ,, Control of Plant Preparedness Commision happens at this time to be the Commissioner of Health-a physician who also happens Operations", it is my view that msider sabotage causm.g core melt is almost a trivially simphsuc proposition for to be knowledgeable in radiation risks--so his response the saboteur. Mostly what is missirg is motivation. The during the Ginna accident or during emergency exercises has been very much a sane one. However, lower-level bunkered safety system approach in Western European countries may provide a workable countermeasare to this functionaries serving in his stead during exercises have threat, and, at the same time, lead to reductions m risk consistently shown a preddiction to start premature mock from non-sabotage accident scenarios as well. evacuations. After Chemobyl, these functionaries are even more likely to want to evacuate--so I am concerned as to what might happen if an accident occurs at a time Does anyone have m. formation concerning what safety
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| ; system capabihties are provided by the existing bunkered when the current Health Commissioner is away, or has safety system concepts? It would seem that by providing left his position, or has had his responsibilities usurped by the Govemcr.
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| both'high-rate, low-pressure and low rate, high-pressure pumps and the capability to use these pumps for vessel The same issues arise on the use of KI for thyroid injection, containment sprays, pump seal mjecuon, cavity blockade (see discussion in the "bealth" section of this flooding, and other purposes, one could design a bunkered Conference)
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| I hope that there are others out there who will add their
| |
| , safety system concept that would be extremely beneficial
| |
| ; comments towards affirming sheltering as the first method m terms of fending offinsider sabotage, external sabotage, of protection, to be followed by whatever action is
| |
| ! and a host of accidents initiated by other causes. Any comments? necessary as indicated by developing events, or as more
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| ; da:a become available to the emergency response staff.
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| ', RESPONSE TO COMMENT #10 IN ACCIDENT _,,,,,.,,,,,.--,.-.+++-=*-*e*
| |
| MANAGEMENT STEVEN C. SHOLLY, MHB TECHNICAL containments / intro M6 No message ASSOCIATES Mr. Holmstrom appears to forget the " martial law"
| |
| , option available to civil authorines in Westem containments /mtro M7, from ehicken,2681 chars, Mon i
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| democracies. Oct 20 09:28:001986 4
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| CHERNOBY1, CONFERENCE.BY COMPT /TER. Sept.29 Oct.17,19a6 Page IV 15 p
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| I __
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| consensus of the knowle:!geable community that such NUREG/CR-2145, SAND 81-0124, September 1981.
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| explosive interactions may be dismissed in the latter 11. M. J. Bird, " Thermal Interactions Between group (Westem LWRs) based on well controlled Molten Uranium Dioxide and Water, An Experimental confirmatory expenments." If Mr. Hurcherson is referring to Ref.15, he is very much mistaken. To my knowledge, no "well contmlled confirmatory experiments" exist Study Using Thermite Generated Uranium Dioxide,"
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| presented at ASME Wm' ter Meeting, Washington, D.C.,
| |
| h HTD-Vl9, November 1981.
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| anywhere in the world. I would recommend that interested 12. A. T. D. Butland et al., " Report on Phase 1 of conference auendees read Ref.15 to note the strong the PWR Severe Accident Containment Study, Winfrith, caveats concermng the subjectivity of the conclusions, and UKAEA, United Kingdom, December 1984, the nearly unammous recommendation by the group that 13. IDCOR Technical Report 14.lA: Key funher research be conducted in order to confirm the Phenomenological Models for Assessing Explosive Steam l assumptions. It would also be reasonable to contact the Generation Rates," Fauske & Associates,Inc., June 1983.
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| chairmen of that study (T. Ginsberg, BNL, M. L. 14. J. H. Gitrus, editor, "PWR Degraded Core l Corraduu, Un. of Wisconsin, and C. Allen, USNRC) and Analysis," NDR-610(S), Springfields, United Kingdom, determine the existence of these "well controlled April 1982.
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| l confirmatory experiments." In addition, References 24 and 15. Steam Explosion Review Group (SERG), "A l 25 evaluated all of the inipiant current assumptions and Review of the Current Understanding of the Potential for l hypotheses used to support some experts' low subjective Containment Failure Ansmg from In Vessel Steam i probabilities for large steam explosions. Experimental Explosions," NUREG-1116, February 1985.
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| l data and technical arguments were provided which showed 16. M. Berman, Sandia, letter to John Telford, that all the hypotheses were either inconclusive or USNRC, " Commentary on the Deliberations and disagreed with experimental data. Conclusions of the Steam Explosion Review Group (SERG)," February 28,1985.
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| REFERENCES 17. J. Hopenfeld, USNRC, Memorandum through L.
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| : 1. G. Chaucer, The Canon's Yeoman's Tale, pp. 509 M. Shotkin to O. E. Bassett, USNRC, " Steam 515 in the " Canterbury Tales," Garden City Publishing Explosions," January 15,1985.
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| i Company, Inc., Garden City, New York. 18. M. Berman et al., "An Uncenamty Study of i 2. W. E. Baker et at, " Explosion Hazards and PWR Steam Explosions," NUREG/CR-3369, SAND 83-Evaluation," Elsevier Scientific Publishing Company, 1438, May 1984.
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| New York,1983. 19. W. R. Bohl, "An Investigation of Steam
| |
| : 3. R. C. Reid, " Rapid Phase Transitions from Liquid Explosion Loadmgs with SIMMER-II," draft report, June to Vapor," Advances in Chemical Engmeenng, edited by 1986.
| |
| James Wei, Vol 12, Academic Press, New York,1983. 20. J. B. Rivard et al., " Identification of Severe
| |
| : 4. "The Explosion at the'Appleby-Frodingham Accident Uncenainties," NUREG/CR 3440, SAND 83-l Steelworks, Scunthorpe 4 November 1975," Health & 1689, September 1984.
| |
| l Safety Executive, report by HM Factory Inspectorate, 21. L. Devell et al., " Initial Observations of Fallout l
| |
| ISBN 011880331 X, Ur:ited Kingdom,1976. from the Reactor Accident at Chemobyl," Nature, Vol
| |
| : 5. G. A. Greene et al., "Some Observations on 321, p.192, May 15,1986.
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| Simulated Molten Debris-Coolant Layer Dynamics," 22. " Core Fragments in Chemobyl Fallout," Nature, Proc. Int Meeting on LWR Severe Accident Evaluation, Vol. 323, p. 399, Ocober 2,1986.
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| Cambridge, MA, August 1983. -
| |
| : 23. USSR State Committee on the Utilization of
| |
| : 6. B. W. Marshall et at, "Recent Intermediate-Scale Atomic Energy, "The Accident at the Chemobyl Nuclear Experiments on Fuel-Coolant Intemctions in an Open Power Plant and Its Consequences," Draft, August 1986.
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| Geometry (EXO-FITS)," Proceedmgs of the Intemational 24. M. Berman,"An Evaluation of the Bases for ANS/ ENS Topical Meeting on Thermal Reactor Safety, Estimating Alpha-Mode Failure Probabilities,"
| |
| San Diego, CA, February 2-6,1986. Pmceedings of the Intemational ANS/ ENS Topical i 7. D. E. Mitchell and N. A. Evans, " Steam Meeting on Thermal Reactor 5. .y, San Diego, CA, Explosion Experiments at Intermediate Scale: FITSB February 2-6,1986.
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| Series," NUREG/CR 3983, SAND 83-1057, Feb.1986. 25. M. Berman, " Comments on IDCOR Report
| |
| ! 8. W. W. Tarbell, Sandia National Laboratories, 14.1A,' Key Phenomenological Models for Assessing l private communication. Explosive Steam Generation Rates,'" presented at the l 9. M. Berman, " LWR Safety Research Program NRC/IDCOR Meeting on Accident Phenomenology and Quanerly Report October-December 1980," NUREG/CR. Containment Loading, Harper's Ferry, W. Virginia, 1509, SAND 80-1304, May 1981. November 29,1983.
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| i l
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| : 10. D.E. Mitchell et al., " Intermediate Scale Steam Explosion Phenomenz Experiments and Analysis,"
| |
| : 26. "Chemobyl: The Soviet Report," Nuclear News Special Repon, September 11,1986.
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| g i
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| i END OF CONTAINMENT CONFERENCE .
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| ; Page IV t8 i
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| * CHEPNOBYL CONFERENCE BY.COMPtKER - Sept. 29. Oct.17,1986
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| , ,- i
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| ^-
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| carned cff in an external shock wave which imme&ately these reactors is considered to be highly incredible" is not begins to decay when it leaves the explosive region. Part correct. There are certamly many experts who believe that 4
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| of the energy is used to evaporate water and create a steam alpha-mode failure is unlikely. However, I believe that the majority, if not all, of these expens recogruze that this O partitioned between the bubble and the emined shockbubble.
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| is a highly subjective Injudgenient, the case andof HE,bethe energy cannot is ro wave. Close to the steam explosion, pressures are scientifically demonstrated today. A review v the expens' generally much lower than for solid explosives because, as comments in Ref.15 will confirm my statement. [Many Mr. Hutcherson points out, the explosion propagation of the pertment comments have been selected and speed and power density are lower than for HE. However, published in Ref.16]. I know that many other experts at a distance of the order of 10 to 20 radii, the underwater would not accept the words " highly incredible."
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| shock wave pressures from TNT and steam explosions can References 12,14 and 17-20 is a sampling of published be quite comparable. results that in&cate far less certamty in the probability of a steam explosion than the words " highly incredible" I believe that we can all agree on the following. There imply.
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| is circumstantial evidence that the in-vessel Chernobyl
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| ' explosion" could have been a " steam explosion," sharmg 1RIGGERING OF AN EXPLOSION many of the charactenstics usually ascribed to such explosions. The key quesuon, for which agreement I do not see any important safety &stmetion between a i probably does not exist, is: Does the occurrence of a "spontancot.s" and an "extemal" trigger. Triggering
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| ! steam explosion or pseudo-steam explosion at Chernobyl translates simply into an event which causes film collapse affect the consideration of such events in LWRs? I and fuc! fragmentation. Such a trigger could be caused by believe that it does. I also believe that an " energetic" natural oscillations of the vapor film blanket, or by a 4
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| FCI, or possibly a number of smaller steam explosions pressure pulse. I believe the distinction is irrelevant in a may have occurred during the TMI accident, and may have reactor, where triggers can be created by falling objects, been responsible for the 2 MP3 pressure spike that pumps tuming on, etc. Many steam explosions have occurred at about 3.8 hours. been accidentally triggered in aluminum, copper and steel foundries, in the paper industry. and in nuclear reactors. It REQUIREMENTS OF STEAM EXPLOSIONS appears that such triggers may occur for accidents at low is or highi 4eares.
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| p No one knows how much of the fuel was liquified, nor what fraction was fragmented, nor what the fragment sizes OTHER POSSIBLE DISRUPITVE MECHANISMS
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| , were. 'Ihe void fraction of the sunoun&ng coolant is also not known. What is likely is that, in various parts of the Funher analysis of the Chemobyl accident may indeed core, there were solid and liquid fuel fragments ranging lead to alternative explanations of the two explosions that from " fine" up to fuel pellet size (11.5 mm), and steam occurred. However, I believe that the scenario involving a and liquid water. It doesn't matter if "only a limited steam explosion followed by a hydrogen explosion amount of water was available," or if "not all the currently fits the evidence as well as, or better than, most fragments were liquid." An upper limit to the thermal other hypotheses. The recovery of what appears to have energy that could be stored in molten core debris for an been molten ruthenium [21], melting point of 2770 K, f
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| LWR is about 186,000 MJ, conesponding to 134,000 kg provides evidence for fuel melting. Ref. 22 also implies
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| . of melt at 2750 K [12]. IDCOR [13] has estimated that a rather strongly that some of the fuel was molten. The PWR vessel may fail if 830 MJ were deposited in a steam recovery of particulate matter "some tens of microns in
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| ; ~
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| explosion. According to their calculations, the complete size around the site" [26] is quite consistent with the thermal reaction of 2260 kg of fuel would be sufficient to debris sizes to be expected in a strong steam explosion fail the vessel. Gitrus et al. [14] stated that " Prompt [7,10,11]. The rapid generation of hydrogen that would containment failure cannot be ruled out at explosion accompany a steam explosion also explains the origin of energies exceedmg about 1500 MJ." Clearly, only a the second explosion - a hydrogen detonation (or l small fraction of the available energy is needed for vessel accelerated flame). Furthermore, this scenario seems to
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| ~
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| or containment failure. agree quite well with the Soviet model of the course of events prece&ng the explosion [23].
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| I am not aware of any data which show that coarse fragmentation and triggering are " extremely difficult to
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| ==SUMMARY==
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| ! produce in western style LWRs." Quite the contrary, there are many experiments which indicate that the I don't believe that any definitive conclusion can be opposite is true: that coarse mixtures can be readily drawn conceming the degree of fragmentation of the fuel, produced and triggered for LWR simulant materials (e.g., or that such fragmentation was uniform throughout the j see 6,7,10,11]. core.
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| It is very unfortunate that no references were provided l
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| The statement that "the steam explosion scenario in for the concluding sentence referring to "the current CHERNOBY1, CONFERENCE.BY COMPtTTER - Sept.29 . Oct.17,1986 Pase 1%17 _ . . ,
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| can be ae= tad from the mean consumption rates of '
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| different foodstuffs and their activity concentrations. + health / intro #3, from sysop,12770 chars, Mon Oct 6 When we consider the activity concentration limit for a 10:12:59 1986 -
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| g foodstuff, we should estimate the radiation doses for both -
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| W aduhs and children. Groups with special diets, such as Tln.E: Paper 2, Heahh vegetanans, should also be considered. Rey often eat a great deal of natural products, such as mushrooms and HEALTH AND SAFETY IMPLICATIONS berries, frequently containing much more activity than OF THE CHERNOBYL ACCIDENT culdvated products. For such population groups - A
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| ==SUMMARY==
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| PERSPECTIVE - .
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| additional limits for consumption of natural products might be needed. Morton L Goldman
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| . NUS Corporation
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| : 4. What is the suitable limit for radiation doses causing '-
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| September 22,1986 no unacceptable health consequences? .
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| I. INTRODUCTION Except for in the immediate surroundings of Chemobyl, no acute heahh consequences are expected. Therefore only The immediate effects of the Chemobyl accident on dose limits for stochastic effects of radiadon are the health of the plant staff and fire and rescue workers are considered. In its publication 40 ICRP gives two such unfortunately too clear. More than thirty have already died dose limits for the population or the critical group. De and about two hundred remain in hospital. It will be lower limit for the first year dose after an accident is 5 several decades before the impact of the accident on public mSv, below which countermeasures are not warranted. health is as completely understood as possible, given the The corresponding upper dose limit is 50 mSv above nature and apparently small magnitude of these which countermeasures are almost certainly necessary. consequences. During the recent IAEA working meeting in Vienna, a substantial body of data was presented by He experiences in Finland from 1965-69 showed that Soviet representatives with respect to the accident, the the half-life for the Cs-137 body content in humans was releases and environmental measurements in the affected about 2.5 a, when no correction for continuous annual regions, and estimates of individual and collective fallout was taken into account. If we conservatively assume that the effective half-life for both external and exposures in the affected populations.
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| g intemal exposure rates is 5 years and the radiation dose ne purpose of this summary is ta review those during the first year is 5 mSv, then the committed dose estimates of the doses (and projected health effects) from equivalent during the next 50 years is about 36 mSv. the Chemobyl accident as they might have been (or be)
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| His gives an annual mean exposure rate of 0.7 mSv/a, affected by a!!emative which is below the value 1 mSv/a given in ICRP emergency responses and actions, for example, from the publication 43 as the limit for people's life-time doses for implementation of emergency plans and action levels humans. The dose rate 5 mSv/a decreases to 1 mSv/a in similar to those for nuclear power plants in the U.S. A 12 years. However, the lifetime dose limit 1 mSv/a is secondary objective is to comment on the basis for current not meant to be emergency plans and, incidentally, the usefulness to used in the case of accident. - public health agencies of such concepts as protective action guides (PAGs)in the light of the public and if the first year dose for humans living in the area of political rea:tions to radiadon exposures of any magnitude highesf~ fallout is of the order of 1 mSv, as estimated in above normal background levels.
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| Finland from the Chernobyl fallout, the risk to an individualis of the order of ten to minus fifth and thus II. DOSE ESTIMATES negligible.
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| Based on the information presented in the USSR In addition to the radiation doses for members of the Working Group report to the IAEA, about 50 mci of critical group, the committed collective dose equivalent for nob!c gases and the same quantity of other radionuclides, the total population must also be nueurd His means prominently radiodine and radiocesium, were released from that if a large population is irradiated to 1 mSv/a, there the Chemobyl plant over the period extending from 26 will be health consequences, but the addinonal risk is April to 9 May, with maximum release rates observed at small compared to other' risks in everyday life. However, the beginning and ending of that period.
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| if there are countermeasures, which can be implemenzd Evacuation of Pripyat, a workers' city within 3 km (two easily, with only minor inconveniences to people, these miles) of the plant, was begun at 2 PM on 27 April, should be considered. about 36 hours after the accident at 1:23 AM on 26 April.
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| Evacuation of the remainder of the zone within 30 km (19 miles) was carried out at unspecified times through 5 heahh/ intro #2, from sysop. No entry. May. Collective doses presented in the USSR report.
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| Page V.2 ' CHERNODYL COSTERENCE.BY.COMPL,TER - Sept. 29. Oct.17,1986 9
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| TopicThree: October 7-October 9: .
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| HUMAN HEALTH IMPLICATIONS ~
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| protection an exposure sate of 1 mR/h, caused mainly by heahh/ intro #1, from sysop,6624 chars, Fri Oct 3 shonlived radionuclides, might be a reasonable value for 11:41:02 1986 informing the public. However, the Chemobyl accident showed that this limit might be too high. People should TTILE: Paper 1 perhaps be informed after a doubling of the normal exposure rate. We must be careful to exclude incidents PRO 11!CTION FOR PEOPLE FROM ACCIDENTAL which do not lust more than a few minutes (probably RADIATION DOSES '
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| caused by a meter error) or which last hours but are caused by radon daughters. In the laner case the rise of the Matti Suomela erposure rate is typeally less than of 0.005 mlUh.
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| Finnish Centre for Radianon & Nuclear Safety P.O. Box 268
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| : 3. Intemal exposure SF 00101 HELSINKI FINLAND 1he internal exposure starts via inhaled radionuclides.
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| The most important nuclides are the isotopes of iodine and
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| : 1. Introduction especially iodine 131. For p,issin, thyroid doses, the activity concentration of iodine in the breathing air must In this paper I will discuss factors which should be taken be measured. This requires gammaspectrometric
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| : into account, when making plans for protecting people against accidents such as that which occurred at measurements of aerosol filters. In order to be able to measure the lodme in organic form, the filter system must
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| -O.. Chernobyl. I assume that the people in question
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| . liveinclude at an activated carbon filter. In the Chemobyl fallout some distance from the accident reactor so that there is no about 85 per cent of the iodme was in an organic form and need for evacuabon. I will consider separately intemal and passed through the particle filter. To prevent thyroid extemal exposures, although the sum of these is essential contamination, stable potassium iodide can be for predicting heahh ccm===
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| administered to block the thyroid. But at what point should this countermeasure be taken, if indeed it should it
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| : 2. External exposure be taken at all? Is the expected dose of 50 mSv to a one-After the agreement ensuring the early notification between IAEA member states in 1986 we can hope that The whole body counter measurements made in Finland informanon on accidents causing radioactive releases is of people evacuated from Kiev, about 100 km south of obtained in good time, if the waming is too late, the Chemobyl, showed that those who retumed on April 30 network of continuously working exposure rate meters were almost uncontaminated, but those retuming on May should give alarm in response to rising exposure rates.
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| I were contaminated with the whole composition of
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| ~!he Chemobyl accident showed that these meters should Chemobyl fallout nuclides. 'the contamination had measure reliably exposure rates from 0.010 mR/h pobably occurred via upwards. The integrated values of the meter readmgs inhalation. The measurements showed that,in addition to should be automaucally fed into the computer system jn lodme, other radionuclides must also be taken into account continuously manned " headquarters". The computer as a source of intemal contamination already in the early system should be capable of producing maps, which show phase.
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| Isodose curves and integrated doses.
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| The most problematic question regardmg internal A computer program to calculate air trajectories of the contamination is the hot particles which, when fixed in radioactive cloud or plume is needed and the tur:g, may cause very high local doses. Although the radionuclide composition of the fa!!out must be there were abundant hot particles in the Chemobyl fallout, known for predicting the behaviour of exposure rates.
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| we were not able to find such particles in whole body The next problem will be at what point the public should be informed. From the point of view of radiation The radiation doses caused by radioactivity in foodstuffs CHERNOaYL CONFEaENCE BY.COMFtfrER - Sgr.29. Oct.17,19a6 Page V.! ;
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| y.
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| only 1012%, although if it had applied to all milk which is at least tenfold less than that from radon in supplies the calculated thyroid mortality would have been, ordmary OUTDOOR air, and 100. to 1,000. fold less than reduced to a total of about 75, or an average individual those from orinary indoor air. High-radon houses can lifetime risk of 1 in one million. Dere are, however, some very practical constraints on the ability of any scale up to risks which are 1,000. to 10,000. fold greater than your proposed action levels. Such conservatism in h
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| nadon to mobilize the resources necessary to screen both the case of NPP accidents doesn't seem to be warranted. 3.
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| urbs and rural milk supplies for 75 million people in a A 5-rem action level for thyroid prophylaxis with K!
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| timely manner. seems too low. In the US, the Food and Drug Administration has recommended an emergency action
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| '#* * ""** "~ '
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| health / intro #5, from 132'di,525 chars, Wed Oct 8 recommended action is merely to divert the contaminated 05:08:03 1986 food from commerce. De FDA also set a preventative His ,si a comment to message 1.
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| PAO equivalent to 1.5 rem to the infant thyroid for which
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| *#"" " ** ****"I'* "
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| COMMENT TO PAPER 1-the contaminant in the food (milk). Here is NO HUne n e PeopeMes 4 a &ug of GREAT A' TTENTION IS BEING PAID TO DIE COMPUTER SYSTEM CAPABLE OF
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| *" **I ('#* *I ""I" Am an mi AssoctaW stated that CALCULATING EXTERNAL DOSES AFTER AN ** ""
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| I I" " *I ACCIDENT BASED ON REAL EXPOSURE RATES * "* * * ** *"*
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| * AND METEOROLOGICAL CONDITIONS " '* "* E'*E"*" '*"*"****
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| WE WOULD APPRECIATE YOUR COM5fENT ON "##**" * "U THE COMPLEXITY OF THE DISPERSION MODEL e TO BE USED: LINEAR OR VARIABLE ( If, as you say, the doses in Fmland were indeed 1RAJECTORY,2 OR 3 DIMENSIONS, ETC. AND
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| ."ghg .w , o THE PARAMETERS TO BE CONSIDERED TO acti9ns , ase e e SELECT A SPECIFIC MODEL. WHICH IS THE radiation expert is willing to substitute risks about which FINNISH EXPERIENCE ON THESE MODELS 7.
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| he knows little for those which he knows to be small.
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| THANK YOU . J.TAPIA.
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| EMPRESARIOS AGRUPADOS. MADRID. SPAIN. health /mtro #8, from jmatuszek,631 chars, Wed Oct 8 h
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| 13:05:27 1986 heahh/ intro #6, from jmatuszek,144 chars, Wed Oct 8 Tin.E: Comment on Paper 2 09:40:19 1986 My compliments, Mort, on a well.nasoned paper, especially for pointing out the tmp of trying to apply the i TrILE: Correction to " health / intro #4" linearity hypothesis.
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| In line 51, the sentence beginning "If very doses of mdio.
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| One correction, however. In the US the emergency
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| * should read "If very high doses of radio.".
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| PAO of 0.15 microcuries !.131/ liter of milk would have
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| , applied to those zones similar to Byelorussia and the Ukraine. De preventative PAO which you use in your health / intro #7, from jmatuszek,2170 chars, Wed Oct 8 paper only calls for a reduction in mdionuclide l 12:50:28 1986 concentration, not diversion. Since this accident happened in early spring, stored feed was probably not available. It TITLE: Comments to Paper 1 appears that the Russian authorities acted well within the
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| : 1. De Lawrence Livermore National Laboratory in the bounds of US regulations.
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| US appears to have done a reasonably good job of i estimating concentrations and doses with their ARAC suin of meteorological codes.
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| health / intro #9, from oparis,408 cbs, Wed Oct 8
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| : 2. If you propose informing the public at a threshold of 15:03:26 1986 1 mR/hr, what do you expect to tell them? Short. lived ,,,, , , , , ,
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| radionuclides at that dose rate are unlikely to exceed the Withdrawn ICRP limit of 500 mrem, and may only produce 10 to 20 miem of total exposure. Analert level which is too low 4
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| will only serve to heighten the public's apprehension
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| * especially if you have no other substantitive information to transmit.
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| health / intro #10, from jmatuszek,1618 chars, Wed Oct 8 15:24:21 1986 g
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| Alerting at only double the normal gamma dose rate TITLE: Effect of Chemobyl Contamination Zone on seems even worse. De levels you propose produce a risk Source Reduction Proposals.
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| Page V.4 CitERNODYL COSTERENCE BY CO$tPLTER - Sept. 29. Oct.17,1946 q,
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| supplemented by ty own estimaans based on data in that document, se summansed in the table below. c least based on the extemal dose rases presented in the report), the total extemal collective dose for the 30 km HI. COMMENTS population group would have been less than 40 % of the
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| ] present dose estimates and.the health '
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| consequences cenainly less than that fraction of Given these eenmates of doses and padected public the present estunate.
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| haakh effects (and with the perfect clarity that hindsight and & stance provide) several comments are appropriate:
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| B. To the extent that controls on milk E5ects of Alesmadve Protective Actions distributed to urban rendents were successful in limidng radioiodme concentrations to the USSR standard of 0.1 microcurie / liter (uCi/I), the A. No er.planation is provided in the Soviet document for the delay In collective thyroid exposure for Eumpean-USSR removing the 24,000 residents from the would be half the value shown in the table, 15 km zone following the complecon of the Pripyat which is based on the geometric mean of the evacuation on the second day. With all due respect to the linear does effect hypothesis, real health effects are mort reported concentrabon ranges and neglects any dose-surpressive effects of KI administranon in likely to appear in the residents of this zone, whose those rrgions. 'the health effects asumate (using '
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| external exposures alone averaged about 45 rem / capita.
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| This value is well beyond the bounds of U.S. PAGs for the ICRP 26 mortality risk of 5 x 10' 6/ rem) the public of 1 - 5 rem (although it falls within the would be reduced to about 1000 deaths. A more consspon&ng Soviet values of 25 75 sem). Had more resmetive standard (such as the US Food and Drug Administration preventive PAG of 0.015 timely evacumuons maintained the per capita external dose uCi/l) applied to urban milk supplies would have of this populanon below 5 rem (not a diffic'.dt challenge, funher seduced the estimated collective dose by USSR DOSE AND CONSEQUENCE ESTIMATES DOSE / REGION O CONSEQUENCE .
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| (Po,o1ation)
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| Pripyat 3 30 km Euro USSR (45,000) (90,000)
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| (74.5 million)
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| Extemal gamma (whole body)
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| Collective Dose, 0.15 x 10*6 1.4 x 10*6 person rem 8.6 x 10*6 (1986) 29 x 10*6 (50 y)
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| Cancer Deaths <-- < 280 ------> < 4750 Per Capita Dose 3.3 16 0.11 (1986)
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| (Zone Range), rem (4.6-54) (.003 .98)
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| Radiolodine (thyroid) .008/y (50 y)
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| Collective Dose, [3 x 10*5]* [3 x 10*6]
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| prson rem [4 x 10*8]
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| ! Cancer Deaths [4] [40] [2000]
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| Per Capita Dose, [6.1]
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| ''" [30] [5]
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| Cs 137 in food (whole body)
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| ! Collective Dose, ----
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| [3,600)(10 d) 1.2 x 10*8 (1st y) i person-rem
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| : 2.1 x 10*8 (70 y)
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| Cancer Deaths I <38,000 (70 y) g PerCapita Dose, [.04] 1.6 (1st y) a t d ty ris CHEaNoaYt. CoNFEaENCE.BY. compt / tea sept.29. oct. 37,19es Pese V.3 ,
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| l
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| (
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| The concem with the tendency to provide estimates of health /mtro #13, from mgoldman,855 chars, Wed Oct cancer induction and mortality is understandable in the 8 19:44:12 1986 context of the auention paid to them by the media and g Ris is a' comment to message 8. their misuse and misunderstanding by cenam elements of W
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| -- - the public. Nevenheless, intelligent application to heahh I would agree that the PAG is intended to be applied in protection of whatever lessons may be Icamed from this all regions, whether urban or rural. My application to the disaster are more likely to result from the consideration of urban population alone was based upon the Soviet report's risks to health than from consideration of " source terms" statement that the control of milk consumption in rural or " doses" in isolation. I think it is recognized by most areas was not practical - the problem of regulating the (and certainly by me) that risk estimators are open to family cow - and hence the assurance that milk above the question when used in this fashion; in my case, the choice Soviet norms was not used by the rural populations could of risk estimators to use was largely driven by the Soviet not be made. With respect to the preventive PAGs, my report. However, no matter which are chosen, whether understanding of their intended application is under those linear or linear-quadratic from BEIR, or linear from ICRP, circumstances in which the actions cause minimal or no the uncertainties in risk fxtors a-e probably not more advuse effects (economic or nutridonal) on the affected important than the uncenainties in dose estimates under populations. Diversion for cheese or milk solids these kinds of circumstances, the fonner being no more production, if feasible, would have served as well to reduce than about a factor of 2.5.
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| both dose and economic impact; however. I suspect neither was practical to implement under the For example, the 30 km region, with an estimated circumstances. collective extemal dose of 1.6 million person-rem, has a cancer mortality expression estimated by the Soviet report as about 280 (2 % of 14,000); the ICRP linear risk factor health /mtro #14, from mgoldman,1388 chars, Wed Oct of I x 10"-4 per person-rem would yield 160; and, the 8 20:15:12 1986 BEIR III linear quadratic risk factor (on an absolute risk his is a comment to message 10. basis) yields 120. I would venture a guess that the total
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| -- collective effective dose equivalent to that populaden is At the outset, I caution all against placing too high a not known within that fxtor. Nevenheless, if we are to degree of confidence on the projections of dose from cesium intake via the food chain; as stated by Marvin be able to plan effectively for the future, it is important to know that there may be more risk to health from exposure g
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| Goldman of UC. Davis, a participant at the Vienna to extemally deposited cesium than to inhalation of meeting, these health effects are calculated from exposures iodine, or from ingestion of cesium than from ingestion not yet received from crops not yet sown on fields and in of iodine. And it is the health effects expressions or risks soils not yet characterized as to radionuclide availability that must be compared, since doses alone (especially organ and based on risk fxtors at deses and dose rates which doses) will not provide that information.
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| have no demonstrated health consequences. Having said that, I would repeat a comment made in the
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| " Containment" session. It would seem that the limiting healthfmtro #16, from mgoldman,2649 chars, nu Oct factors for containment (and other engineered safety 9 07:31:11 1986 systems) performance are not the health effects, but rather - -
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| the need to prevent the escape of fission products which TITLE: Comments and Questions for Paper 1 - Matti can contaminate land and fxilities and prevent their Suomela subsequent use. TMI clearly demonstrated that core Rese are some comments and questions primarily for damage prevention systems are more strongly justified by Matti Suomela:
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| the need to protect the investment in the plant (an economic jusdfication) than by the need to provide public 1. He problem raised about the radiation dose rates at heahh and safety protection. It seems to me that which the public should be INFORMED should not be a Chernobyl has confirmed the economic justification for difficult one,IF such information is conveyed together the modification of containment systems to prevent the with recommendations as to the actions (if any) that are release of such fission products as cesium and iodine with appropriate to be taken. Whether the value is 1 mR/h or capabilities for significant residual contamination, or some arbitrary fraction of background is almost economic impact on exporters, either international or unimportant, as long as the report is accompanied by domestic. Information that will guide the public actions and information they can use for perspective to evaluate their r risks; e.g., that the ' current' exposure rate is double the h.alth/mtro #15, from mgoldman,1929 chars, Wed Oct normal background in that area, but is still less than the 8 22:01:51 1986 normal background radiation level in Denver, Colorado, or His is a comment to message 12. . Chamonix, or that the risk from the increased exposure, if
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| - - - - - - continued for X years, would be equivalent the risk from l Page V4 CllERNODYL COSTERENCE.BY.COstPtfrER Sept. 29. Oct.17,1986 9:
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| .-. .~ .- - - . - - . . . -_ _.. - -_ -. _ .
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| : Compenng the number of cancer deaths in Paper 2 to increase in thyroid cancers is hard to believe without
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| ;o the telease asumanes for Chemobyl,it appears that Cs 134 extensive substanaanon of the derivation of that number.
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| and Cs 137 may be more limiting than I 131 for a severe As Mort Goldman has irvirated the collective thyroid A accident. Esemates of deaths due to extemal gamma doses may be substantial; more importantly, however, the V radisoon and from food consumption over decades exceed average doses, e.g., in the populanon living within 30 those from radiciodme uptake by an order of magnitude for km, may be of the order of 100 rad or so, considenng the i
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| the near-in populationsand by four fold for the Euro, conenbution of short-lived radionodmes, inhalation USSR populanon. Assuming half the WB gamma dose is exposures, and external gamma exposures. If (say) hom radweeium, of which only 1 to 10 mci were 100,000 peop!e would have received doses of this order of
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| , released, it appears that about 10 to 100 cancer deaths per magrutude, one might expect (using risk factors from t
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| mci released might develop. For I 131 and Te-132, the NCRP Report 80 (1985)) between 100 and 1000 release of 30 to 50 mci suggests that about 0.1 to 0.5 radiogenic thyroid cancers, and maybe three times that deaths per mci might develop in the near in population. number of thyroid nodules. Given a normallife time
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| ; "Ihus radiocesium seems to have about a hundred-fold
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| ' incidence of 250 thyroid cancers in a populanon of that greater risk per curie than does radaoeodme.
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| size, even the lower estimate should be easily detectable l De proponion for the larger offsite populauon .Manmek's esumate of a 20 to 70 fold lower effectiveness appears to be of a similar magnitude. of radiciodine exposure vs. extemal x-rays appears out of Per capita doses of the magnitude listed by Goldman thin air, and many of his other statements of a medical indicate that large populations will be relocated from large nature are controversial, to say the least. Nevertheless, land areas if EPA's proposed relocation PAGs are adopted. his statement that the thyroid issue is one of the
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| } Dis would be analogous to what the Russians have been imponant unresolved issues is correct, and I hope that we forced to do within the 30.km zone. will see considerably more information fonhcoming from
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| . It now appears that CsI, instead of being the bellcow the USSR.
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| !' to lead the US nuclear industry from its emergency
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| ) response problems, will prove to be an albatross. 2. Risk estimates.
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| ! Does anyone care to comment on the effect that s Goldman's astimates may have on the future of NPPs There appears to be a strong tendency to predict cancer
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| ; which can impact on very large populations (eg, Indian cases or deaths in the exposed populadons, i Point, Zion, Pdgrim, Shoreham to mention a few)? notwithstanding the extremely imprecise dose estimates, i
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| O heahh/mtro #11, from operis,497 chars, Wed Oct 8 and the fact that the 10,000-manrem-per. cancer-death number is not the correct number to use (as repeatedly stated by NCRP and ICRP). His number implies
| |
| ! 15:33:58 1986 assumptions that are adequate for radiation-protection purposes (i.e., for planning of radiation protection
| |
| '1 TILE: Decontamination off Vegetables: measures), but are not meant to be used for the calculation A research team at the University of Konstanz reponed of actual health effects. In the first place, the number j in ENVIRONMENT, Vol. 28, No. 5, pp. 6 43, that assumes complete expression of the risk. In a population i fallout from Chemobyl could not be emoved from locally of different age groups, this assumption is not tenable, grown vegetables by washing them in cold water. By and one would have to use a life-table approach to i
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| personal communication they reponed that washing calculate the corrected risk numbers. I estimate, very
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| ! removed only 20% of the radioactivity on vegetables. Do roughly, that this alone reduces the " cancer deaths" by a j i any conference participants have additional information on j
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| factor of two. Secondly, the number is derived from high.
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| this subject?
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| dose, high-dose-rate exposure data, especially the i i
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| Hiroshima / Nagasaki data. Assuming a dose rate efficiency l Oscar Paris
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| ; reduction factor of 2 or 3 (NCRP, BEIR III), this would U.S. Nuclear Regulatory Commission funher reduce the published nurabers with a like factor.
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| De major problem I have with analyses of this kind is
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| ( '
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| that they tend to use " conservative" numbers, rather than
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| { health /mtro #12, from dbunch,3325 chars, Wed Oct 8 j "best estimates". You have seen what confusion the use 16:01:50 1986 of a conservative number for the population exposure j
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| from cesium intake has brought about, especially when a l I have two principal comments to make, that apply to reduction with (at least) a factor of ten (!) was ascribed by i nearly all participants so far.
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| opponents of nuclear power as an effort by pro-nukes to cover up the "real* danger of radiation. In short, let's be a i 1 little more scientific in our efforts to estimate the health O .De matter of thyroid exposure. 4 vi 'iceseeec erchere6>> a h appears to me that the USSR data are particularly somewhat less inclined to be " conservative"!
| |
| scant with respect to the magnitude and extent of the (104/86dwthiessen) thyroid exposures. Deir estimate of a one percent
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| . . CifEn NOBYt. CONFIRENCE.BY. COMPT?TER a Sept.29. Oct.17,1986 Pase V.s [S l _ _ _ _ _ _
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| | |
| which is transferred to our computer through telephone . survey of subjects potentially exposed to fallout radiation.
| |
| network. FMI uses a mixed Gaussian-gradient transfer -- -
| |
| Am. J. Med. 56: 457-63,1974.
| |
| model, i.e. the model uses a gradient transfer description of the vertical distribution of activity, while the horizontal
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| : 7. Ralbson, M.L., et al: nyroid nodularity in children.
| |
| JAMA 233: 1%9-72,1975. -
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| g distribution is treated as a simple Gaussian. De trajectory is calculated to the length where either the distance from the power plant exceeds 100 km or the time exceeds six healthfmtro #20, from jmaclellan,345 chars, nu Oct 9 hours. It must be mentioned, however, that the first 13:00:07 1986 version of our system, which is not operable yet, will use This is a comment to message 12.
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| source term data rather than measured exposure rates as its Dere is/are comment (s) on this message, basis; measured exposure rates will be used only for correcting isodose curves calculated first on the basis of It seems to me that if we are trying to instill public source term data. conhdence in our estimates of heahh effects we should be
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| . reporting what we believe the most likely effects will be based on the most probable dose and rish values.
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| heahhrmtro #19, from jmatuszek,2204 chars, nu Oct Uncertamties in the estimates should be covered by 9 12:48:38 1986 applicable error estimates rather than reporting worst case scenarios.
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| TTILE: Comment to heahhrmtro #12 from dbunch The estimate of a 20- to 70-fold lower effectiveness of =.
| |
| ! radioiodine exposure vs. external x-rays was neither mine health / intro #21, from lleach,193 chars, nu Oct 9 l
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| nor "out thin air". De estimates of so much lesser risk 13:37:51 1986 were first made by Maxon and Saenger and were verified his is a comment to message 14.
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| independently by Holm and coworkers. Dr. Eugene Dere is/are comment (s) on this message.
| |
| Saenger appears to be well qualified for such studies, and -
| |
| . his work has been published in appropriately reviewed his implies that core melt mitigation sy-tems shocid joumals. While not as well controlled as the Saenger or be provided on an economic basis. De s7 dies I have Holm studies, the survey by Rathson tends support to seen indicate that few, if any additional measures would be Saenger's esumate of lowered risk. Ralbson was unable to find any excess of thy oid nodularity despite exposures justified on this basis. g estimated at 10 to 600 rad. References for these studies are listed below. healthfmtro #22, from mgoldman,849 chars, L Oct 9 Dr. Rosalyn Yallow has testified before Congress that 14:40:26 1986 her review of a few-hundred-thousand cases cf diagnostic I- his is a comment to message 20.
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| 131 administration also failed to show any statistical difference in the incedence of thyroid tumors despite I agree totally with the suggestion that, when dealing exposures in the range 50 to 150 rad. Her review is not with a situation about which one has first-hand, direct been published, except in committee records, as far as I knowledge, best estimates of both dose and heahh effects know. should be used. However, in the current instance I have l .. no basis for second-guessing the dose estimates as l
| |
| | |
| ==REFERENCES:==
| |
| presented in the Soviet report except as noted in my paper j 1. Maxon, H.R., Saenger, E.L., et at: Clinically for the thyroid dose and as modified in Vienna with respect I
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| important radiation associated thyroid disease JAMA to the cesium ingestion dose. Given the uncertainty in 244: 1802 5, 1980. the dose estimates by the Soviets, and the current flux in
| |
| : 2. Maxon, H.R., Saenger, E.L., et at: Ionizing radiation effects as influenced by the Japanese data, the differences and the induction of clinically significant disease in the between the Soviet effects estimates and those obtainable human thyroid. Am. J. Med. 63: 967 78,1977. by using BEIR III linear-quadratic relationships are, as l 3. Holm,L.E., et al: Incidence of malignant thyroid '
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| noted in my comment #15, not materially different insofar l tumors in humans after exposure to diagnostic doses of as they may influence post-accident planning either in the
| |
| ( iodine 131. J. Nat. Cancer Inst. 64: 1055-59,1980. USSR or elsewhere.
| |
| ! 4. Holm, L.E., et at: Incidence of malignant thyroid Mort Goldman, NUS Corp tumors in humans after exposure to diagnostic doses of iodine 131. II. Estimation of thyroid gland size, thyroid radiation dose and predicted number of malignant tumors. health /mtro #23, from mgoldman,234 chars, Thu Cct 9 g
| |
| , J. Nat. Cancer Inst. 65: 122124, 1980, 14:46:55 1986 W
| |
| ! 5. Holm, L.E., et at: nyroid treatment and its possible nis is s' comment to message 21.
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| I influence on occurence of malignant tumors after -- --
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| l diagnostic I 131. Acta Radiol. Oncol.19: 455-59,1980. I would not argue that more systems are needed; my
| |
| : 6. Rallison,M.L., et at: nyroid diseases in children - a point, somewhat poorly phrased, was that providing '
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| Page V.8 CHERNOBYL COSTIRENCE BY COMPtTTER - Sep:. 29. Oct.17,1986
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| '2
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| . - . = . . -- . _ . - - . .. _ _ - - - . .--
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| i.
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| smokmg Y cigarettes per year transport cf rasoactivity to the Finnish air-space is believed to have occured.
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| : 2. There would seem to be slight reason to change '
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| p from the ICRP recommendanons for countermeasures, in The simulation of the cloud is based on &spersion
| |
| -\ my view. The risks from such accidents are low both in conditions (stability, mixing licight, rain occurenced) terms of probability of the same population being affected Dese parameters are determined along the trajectory on by more than one such event in a lifetime and, as has been the basis of temperature, humidity, horizontal winds on unfortunately danonstrated by the Chemobyl accident, by standard constant pressure levels, verocal winds of the the very low per capita doses at greater distances from the layer 500-1000 mbar, net ra&ation, surface wind speed, site. De risks to the public, however, need to be character of terram etc.
| |
| considered in the context of the case with which they can
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| , be avoided; if the risks are high to a particular group De model is capable to consider changing dispersion
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| . (infants from fresh milk or I.apps from reindeer meat, for conditions, such as rain, mixing height and wind speed 1 example) it may be, simple to avoid a smaller dose in one during the transport. On the other hand it is difficult to case (by providing altemate milk supplies to infants, for take into account possible transport of radioactivity at example) and very difficult to avoid a larger dose in very high altitudes.
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| another without alwrituting a greater risk (starvation or social dislocation). Dese are not decisions orjudgments In general, the agreement between the model calculations that can be made by ICRP, but must be made in a and observed ra&ation levels has been quite good.
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| particular national perspective.
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| /1/ G. Nordlund et al, Health Physics Vol 49, No. 6, pp.
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| : 3. In the same vein, you have esumated the first year 1239-1249, 1985.
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| dose in the area of highest fallout to be on the order of 1 mSv (100 mrem); from your effective half life value, that
| |
| ' would indicate a dose commitment of about 7 mSv (700 heahh/ intro #18, from msuomela,2213 chars, Thu Oct mrem). Jack Valentin of the Swedish NationalInstitute 9 10:14:33 1986 of Rmaarmri Protection, at an AIF meetmg this week, His is a comment to message 5.
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| ,. indicated a wwvuding value in the area of maximum -
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| deposition of about 5 mSv (500 mrem) over 50 years, and
| |
| ;. an average for the entire population over that period of 9.10.86 about 1 - 2 mSv (100 - 200 mrem). Have you made an De choice of the dispersion model depends, of cource, estimate of the collective effective dose commitment for on the nature and purpose of the system in which the the population of Finland from this event?
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| ] model will be included as a part. If the system is intended to operate as a real-time system that is used by emergency
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| ; Mort Goldman, NUS Corp control staff in early phases of the accident, it should be an easy-to-operate system and it should perform health / intro #17, from ppirila,1607 chars, Du Oct 9 calculations as quickly as possible; so the complex and
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| ; 09:13:08 1986 computer-time-consuming three dimensional dispersion his is a comment to message 5. models are almost certainly out of question. On the other Dere are additional comments to message 5. hand, if time is not considered to be a crucial element, the choice between two and three dimensional models depends on other factors such as computer capacity, desired accuracy of results, and so on.
| |
| Calculation of the transport of radioactivity from Chemobyl to Finland From: J. Rossi and P. Pirila, Technical Research As for choice between linear and variable trajectories,it Centre of Fmland s known that under certain meteorogical condidons 4, simple linear trajectory models give quite erraneous De calculations of the long range transport of results. Derefore the system should be capable of treating variable trajectories properly at least to some extent,
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| , radioactivity originating from Chernobyl have been performed in Finland using the model TRADOS developed Also, the dispersion model should include a possibility to ,
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| use different deposition velocities for different nuclides. '
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| jointly by the Meteorological Institute and the Technica!
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| l Research Centre /1/. De model TRADOS utilizes air trajectories, based on observauonal data, which are We in STUK have for some time been developing a computer-based real time system for off site dose
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| , calculated at three hour mtervals in a two-dimensional grid f^gwith a mesh width of 150 km (at 60 degrees Nonh). De calculations during nuclear power plant accidents. In our L/calculauons are performed using numerically analyzed system trajectories and dispersion patterns are calculated i
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| winds at the 850 mbar pressure level. His corresponds by the Finnish Metcorological Institute (FMI). During quite closely to the altitude at which the donunant accident conditions FMI will calculate a new trajectory once or twice an hour. De data is then stored in a file
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| , Cif ERNOBYL CONFERENCE.BY.COMPL,TER ~ Sgt.29. Oct.17,1986 Page V.7 y t i
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| _.__..,_m___ _ . . , . _ _ . ~ , , . , - . _ _ . _ , _ _ _ _ _ _ _ _ , _ _ _ _ , . _ , _ - _ _ , _ _ , _,m,__._ _. . _ _ n
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| radiation protection practice, conservatism in evaluating - the situation at the moment of inudiation the uncertainties would necessarily drive the Task Group - clinical signs such as naushea, vomiting, paleness, and especially the Committee 57 members and other -
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| reviewers to adopt a value which would present the least shock -
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| - hematological depletion, especially lymphocytes g
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| potential harm. After all, an excessively high risk factor in the first 3 days, then on cytogenetic evaluation of doses in radiation protection practice may only cause an inconvenience to the researcher, physician or waste - Are these criteria envisaged in other country ?
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| disposer. De resulting dose saving from being overly conservative would seem to be easily justified for the little In the soviet report presented in Vienna, Dr cost of the inconvenience. GOUSKOVAA is affirmative on the fact that the HOWEVER,in the case of a severe accident the cost irradiations were homogeneous. She based this affirmation of being overly conservative on the iodine risk factor is to on the results of cytogenetic studies, saying that force the public to ingest a potentially harmful drug; a distribution of cells with dicentrics were not differents of drug for which the risk is not well established. As I have the theoritical one (ihA by Poisson distribution),
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| stated in my other messages, we reed to use the best-available risk factors for both the radiciodmes and for KI, ne question may be asked if this criteria is sufficient for not the most conservative. Presumably, when we have the estimation of the homogeneity of the irradiation, such factors the uncertainty in each will be comparable, so which is crucial for the treatment.
| |
| that the full range of risks can be assessed for each side of the risk / benefit equation. On the whole, is it possible to have the detailed In answer to the other part of your comment organisation set up in different countries represented at conceming the shorter-lived radiciodines, I have focused this conference? No more unread messages in this topic.
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| my discussion mostly on the issue of I 131. But that is because the issues which relate to the short lived radiciodmes have even greater uncenainties than those for healthfmtro #29, from msuomela,822 chars, Fri Oct 17 I 131, Sheltering is an especia!!y effective, low-risk 05:38:30 1986 option to mitigate the effects of the other radiciodmes; as His is a comment to message 7.
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| is the use of simple breathing protection. Unless KI were -
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| distributed in advance to each household, a call to the public to come to KI distribution centers in the midst of TITLE: Response to comment 7 g
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| an accident would only worsen the exposure to short lived 1. I agree that in the point of view of radiation risks I radiciodines. Furthermore, I question the effectiveness of mR/h is low and there should not be any need to inform late use of KI - an excess of stable iodine circulating in the public. (The limit to wam people in Finland is 20 the bloodstream may have the effect of increasing the dose mR/h). But if you don't inform the public in the very to varios organs, rather than decreasing it. This is a very early phase, which the exposure rates are still increasing, complex question for the emergency planner. you will be accused that you have hidden essential Dere remains much to be done before I would be information the public has right to know. What else you prepared to risk the use of KI in New York. can tell depends on your emergency preparedness system. I think similar problems were encountered in the case at TMI-2 accident.
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| health /tntro #28, from sysop,1403 chars, Wed Oct 15 09:57:02 1986 4. There might be a misunderstanding. The actions or countermeasures were discussed on general level. The risk l T11LE: to in individual is of the order of ten to minus fifth and
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| ) thus negligible to individual, but the discussed actions can J.LAFUMA be used to lower the collective dose.
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| Institut de Protection et de Surete Nucleaire CEA, FRANCE health /mtro #30, from msuomela,569 chars, Fri Oct 17 05:41:32 1986 At CHERNOBYL when considering the actions This is a comment to message 16.
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| undertaken by soviet specialists faced with 200 people -- ---
| |
| overexposed some questions arise : TITLE: Response to comment 16 Are the 4 categories of severity (AIEA ) for selection 1. I agree with your proposal to relate radiation risk to of the patients used in other countries? other more well understood risks. However, when we compared the exposure rates to normal background rates De selection of the patients were carried out based this was also critisized. People experienced e.g. five times on normal background as very dangerous in spite of opposite Page V.10 i CilERNOBYL CONTERENCE.BY.COMPtTTER - Sept. 29. Oct.17,1986 it
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| -.:v systems which produce acceptable public health protection that "other statements of a medical nature are does not necessarily produce adequate investment controversial". Since you don't say what the controversy
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| . _ _ protection. may be, I will take the liberty of amplifying on those
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| ,. :Most Goldman parts of my message #4.
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| *^
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| s - De quesnon I raise conc,errung radioiodme contribunon to early deaths and injuries stems from henhhrmtro #24, from dbunch,2207 chars, Du Oct 9 SANDIA calmkh* summarued in NUREG-0772,
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| ; 16:03:28 1986 D wherem 50% of early deaths are attributed to W i: a, something like 30% of early injuries, also. How else can -
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| TTILE: Comment on healtMntr #19 that be except frorn radiosodine irrmaanno of blood-Comment on healtMntro #19 forming organs?
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| As for the detrunental effects from using KI, there is a The 20 - 70 fold lower effectiveness of "radioiodine" multitude of references in the medical literature that verify
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| ; refers, I presume, to Iodme-131, as compared to x-rays.
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| ' their existance. What is missing fmm the medical De references given nearly all apply to lodine 131; the literature is a definitive value for the risk associated with Rathson studaes are now in the process of being updated. the use of iodme. Typically they are quoted as being Deir lack of findings may be related to the relatively " low", a nonquantitative and completely uncancfactory short time between exposure and effect (and, of course, to I deaWon for the needs established for severe accidents.
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| uncertamties in dose). NCRP Report No. 80, " Induction i After 15 years with the Health Department, my experience of Dyroid Cancer by Iomzmg Radianon",1985, contams suggests that most physicians and pharmacologists all of Manmek's references, and quite a few more. De consider risks between 1% and 10% as " low". Risks l Commit.ec, lookmg at all the data, however, only between 0.1% and 1% are often described as "very low".
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| '; recommended that "I 131 be considered to be no more than Usually risks below 0.1% are not worth considering. So, one-third as effective as external radiation in the induction when I read that the use of KI presents a " low" or of thyroid cancer in the general population" (NCRP, " negligible" risk, I tend to consider that statement of risk i
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| . loc. cit., p.54). Although this recom-adah is as large against 5 x 10*-6 per rad, even when the thyroid
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| ; explicitly meant to apply to radiation protection practices, dose may be in the range 10 to 100 rad. If I-131 is indeed
| |
| ; it clearly is based on uncertamties with sespect to the less effective for inducing cancer death, the risk from I-131
| |
| ,- protective effects of dose rate and dose distribution usually may approach 10*-7; in which case, there is almost no
| |
| . referred to when discussing the lower effectiveness of I- thyroid dose high enough to warrant administration of KI i' 131. Finally, Yalow's numbers have not been published within the limits of our current understanding of its risks.
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| in the scientific hierature, and until that has been done, no If anyone knows of definitive studies which establish j conclusions can be made based on her statements. quantitative s13 4
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| risk factors for KI admmistration, I would appreciate the But above all, the situanon in Chemobyl, especially at references.
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| short distances, is not charactenzed by exposure to I 131 We must require the same level of certainty ( or i only, but to a range of shorter-lived radioiodmes (I refer uncenainty) on both sides of the risk equation when we
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| '; here to the risk from inhalation only, of course), attempt oc advise the public as to the protective steps it combined with extemal exposures of tens of rads received should take. It serves everyone ill, if we radiation i
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| within a period of two days. De I-131 exposure through specialists substitute for a "known", small risk some the milk pathway may well have been minor, as the unknown, but much larger risk. As the old proverb stated, evacuees were provided with milk containing " allowable" " Don't pray too hard for the death of the king, for the new t
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| contentrations within two days after the event. As far as I king may be worse."
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| know, there is no good information of the impact of all exposure pathways on thyroid doses, and I do not feel that -- ---- -- -
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| i the assumed lesser effectiveness of I 131 is a major healtMntro #26, from jmahic7elt 84 chars,Fri Oct 10
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| : argument in rejecting the possibility of an increased 15:20:21 1986 l incidence of thyroid cancer and nodules in the expcsed -
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| i population close in to the plant. TIILE: Correction to #25 i
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| (jwthiessen; 10/9/86)
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| ; Ignore the line readmg "s13". I missed it on the listing.
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| heahMntro #25, from jmatuszek,2384 chars Fri Oct healtMntro #27, from jmatuszek,2276 chars, Mon Oct i 10 15:10:15 1986 13 18:19:07 1986 TITI.E: Funher comments on healtMntro #12 from TfILE: Comment n Message #24 from dbunch
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| ! dbunch.
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| You answer in your own message why NCRP 80 does In addition to questioning the lower risk factor for I- not apply in a case like this one. Because the NCRP l 131, which I hope my message # 19 answered, you say recommendation is explicity stated to apply only to j,, CHERNOaY1. CONFERENCE.BY COMPtfrER - Sept.29 . Oct.17,19s6
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| . Pase %9
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| . e o
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| e M
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| e e
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| e o
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| O l
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| T i
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| I O
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| -~
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| y 4 .
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| methods, screemng techniques, etc. are necessary and are and then i. .ys d to ultimate &sposal facilities. Agam, somewhat different than in the operstmg case. ,, special anention is required because of unusual -
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| ra&onuclide combinations, presence of fuel, high overall
| |
| -Data Acquisition: rad levels and the like. Also, positive steps may be As a prerequisite to an effective plant decontamination renary (such as installation of catalytic converters) to
| |
| - effort, it is necessary to determme the source and prevent b.uldup of explosive concentrations from charactensucs of the ra&oactive matenal in quesnon. radiolytic decomposition within waste storage containers. .
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| Dese data may be particularly difficult to obtam in areas of high background dose rate and multiple ra&oactive -Determining Suitable Post-Recovery Conditions: -
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| sources, and innovative methods may be required. Certainly at Chernobyl the long-term post-cleanup Examples of informanon needed are radionuclide mix and condition is not one previously envisioned, either by distribution, adherence to surfaces, depth of penetracon, regulatory agencies or the plant designers. Care must be ec. Without an effective data acquisition program, decon taken to insure that the conditions selected are acceptable efforts can be ineffective, both from ALARA and a cost with respect to potential for funher accidents and/or and resources standpoint.
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| environmental hazards. Sensible and conservative
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| ' analyses must be employed to establish suitability of the
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| --Ex; Reactor Cnocalir/ Prevention: conditions over an extended penod.
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| Potential presence of fuel outside the reactor in unknown quantines and configurations demand a very De third category of interest is in off-site conservative and cauuous appoach to preclude inadvenant decontamination. We understand here that the Chernobyl criticality. As an example,in flushing piping systems problem is severe and largely unprecedented (although the and cleaning cubicles, positive steps must be taken to Windscale expenence in England in 1957 may offer at ensure that accumulations of fuel in enucal configurations least a staning point in this area.) De lessons being
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| ~
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| are prevented in all cases. Such positive measures may learned at Chemobyl now in off-site cleanup have include use of neunon posson and critically safe potentially very high value and should be followed geometries in flushing systems and waste receptacles. closely, y-ihl-ly in the following areas:
| |
| -Decontammanon Techniques: - Contaminanon levels and distribution correlated with Dere is much to be teamed regarding the effectiveness accident meteorology
| |
| , different techniques under different circumstances. In -Decontamination techniques and their effectiveness particularly severe sinwians, the use of robotically -Contaminanon mobility, including recurrence of applied methods deserves special attenoon. Consideranon contamination in decontaminated areas,' apparent must also be given not only to the removal effectiveness migration, or other changes in contamination levels as a of various decontamination agents but also the function of time, again correlated with meteorology, and mri.i.ge.bility of by-product waste forms. the like.
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| -Recontaminadon Prevention: In general, the importance of good instrumentation and Proper steps must be taken to prevent recontamination thorough, r--t- h1 recordkeeping is extremely high.
| |
| of decontaminated areas. These steps include isolation or As unfortunate and consequential as the accident at sealing of cubicles, mahdan of heating and Chernobyl has to be, the simple irreversible fact remains
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| ~
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| , ventilating systems, and the like. that it h.pgi.ei. It is our responsibility now to learn as much as we possibly can from that experience, to use that j -Liquid Waste Processing Methods: knowledge in a positive way to effect an even safer nuclear l'
| |
| Cleanup of the contaminated facility is likely to generation on a world-wide basis.
| |
| involve decontamination of large quantities of contaminated liquids. Again, this situation is likely to be very different from operational water processing ones management / intro #3, from sysop,5304 chars, Du Oct because of higher concentrations of radioactive matenals, 9 17:00:31 1986 potential presence of fuel, unusual chemistry conditions Dere is/are comment (s) on this message.
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| (such as from decontamination agents) and the like. - -
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| Ca% ion must be given to use of simple and flexible TITLE: Paper 2 systems. For example, at TMI 2, a very satisfactory experience was Fained in the use of inorganic ion THE CONTROL OF OFF SITE CONTAMINATION j exchange media which permitted very high and stable fission product loadmgs. SF Hall and JH Gitrus
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| \_) Safety & Reliability Directorate, UKAEA
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| -Storage and Waste Disposal:
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| : i. Solid waste material extmeted from decon fluids and INTRODUCTION. During and after the accident at
| |
| ; water processing activities must be safely handled, stored Chemobyl the Soviet Union has faced enormous -
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| Pese VI,.2 CHERNOBYL CONFERENCE.BY COMPtfrER - Sgt. 29. Oct.17,1986 f
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| : y. .w-,-7,,,c--, - - - -.. v-.,m._ ,-.,.#.,m._m mmw,,..m..._ _ . _ . _ _
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| reassurance effects. commitment for the entire population is approximately 1 2 mSv and the corresponding collective dose commitment
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| : 3. The effective half-life value used in example was quite 5000-10000 mSv. -
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| conservative. An estimate of the average dose END OF HUMAN HEALTH EFFECTS CONFERENCE o
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| O e
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| e l
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| 1 l
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| l l
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| l l
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| l
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| ,, CllERNOBYL CONTERENCE.BY.COMPLTER Septl9 Oct.17,1986 p.g, y,g g M
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| THE IMPLICATIONS OFTHE CHERNOBYL 4 concrete steracnons needs to be understood, and ACCIDENTFOR ACCIDENTMANAGEMENT mitiganon schemes developed if necessary (e.g., what -
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| matenals should be poured on the melts). Resesch has Marshall Berman produced computer codes capable of analyzing some of Sand a NanonalLaborneories these quesnons. Calculations-should be performed to '
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| Albuquerque,New Mezzo, USA determme the threat from aerosol production and the potennal for basemat penetranon. It might be wise to Advanced knowledge concerning severe accidents plays develop some advance saategies and mitigation systems an important mie in risk assessment, reactor regulation, that would decrease the vulnerabdity of the air and water accident management, and the public acceptance of nuclear table in the unhkely event of an accident.
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| power. Dis paper addresses the question of accident management and what can be leamed from Chernobyl. Long Term Decontamination The key issues as I see them are: l We should be able to learn much from the Chemobyl
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| : 1. Evacuanon management. {
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| sF=e, both with respect to short-term responses '
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| : 2. Fire control.- (days) and over many years. The Russian plans for long-
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| : 3. Muumization of the threat to the atmosphere and the term decontamination and isolanon appear to be well water table.
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| thought out. We need to carefully monitor their progress.
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| : 4. long-term decontaminanon.
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| : 5. In-vessel and in containment accident terminanon. Accident Terminanon
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| : 6. Ensuring control of plant operations.
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| Given that an accident has been initiated, the most Evacuanon desirable result would be to arrest the accident before the ,
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| Although there was some delay, the Russians were failure of the vessel or containment. Some people have able to evacuate 49,000 residents in 2.5 hours with a fleet T*H a " blind" approach "to add as much water as of 1000 buses. An accident in an American plant might possible to a Western-type LWR as soon as possible." '
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| involve the evacuation of many more people. De U.S. This is probably an excellent saategy prior to core melt.
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| Nuclear Regulatory Commission requires evacuation plans However, experiments at Brookhaven and Sandia National for all plant sites. De various parties (utilities, Laboratories have shown that pounng water onto molten hvemment, regulators) should review these plans in lightcore materials can sometimes lead to a steam explosion.
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| ; of Chemobyl. All parties should agree as to what accident With this knowledge, there may indeed be situations indscators would require an evacuation to begin, how it where the blind pounng of water would not be advisable.
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| would be conducted, and where the people would be Most research is needed on this subject. It may be
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| . evacuated to. s possible to show that explosions in this contact mode l .
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| (water onto fuel) are less likely at high ambient pressure,
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| ! Fire Control .
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| or with saturated water. If this can't be shown, then a reasonable accident strategy might be to introduce
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| ; Hydrogen combustion occurred at TMI and ChemobyL quantities of water that are insufficient to breech the ,
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| l Research has been conducted to ensure that key safety vessel, and attempt to trigger a sequence of small steam l equipment within containment would survive hydrogen explosions, perhaps by cycling the pumps on and off.
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| 1 bums and other types of fires. However, containment ,
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| Introducing water in pulses in this fashion might permit I failure due to energetic phenomena (steam explosions, cooling the core without endangering the vessers hydrogen detonations, high-pressure melt ejection) could integrity. TMI may also have shown that the core can involve the dispersal of molten fuel and cladding outside continue to melt within a " protective" crust, even after of containment. Fires ignited and maintained by these hot water flow has been restored. Strategies for safely materials could be very difficult to extinguish. l terminating the accident under these conditions may again -
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| Funhermore, fire fighters would place themselves in great require that water be introduced in pulses and triggered to jeopardy. Additional research might be devoted to fighting cause muhiple small steam explosions, rather than a large fires outside of containments, possibly using automated one.
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| equipment, robots, and aircraft. Other extinguishing .
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| i materials besides water need to be available. De Russians drained their equivalent of a
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| ( " suppression pool." Dis may have been done to avoid Dreats to Atmosphere and Water Table the possibility of another steam explosion if molten core ,
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| i materials poured into the water. Dere may be some ,
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| O.inimize the spread of fission products. It is important toIf containment is breached, Westem reactors that are vulnerable to ex vessel steam explosions, possibly the BWR Mark II design. nese understand that pounng water on molten fuel might cause plants should be analyzed to assess this possibility, a steam explosion, quench the fuel, or do nothing.
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| Similarly, the rate of production of aerosols from core.
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| Page VI 4 CHERNOBYL CONFERENCE BY.COMPtTTER - Sgt. 29. Oct.17,19s6 i
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| . . . . . . , . . - - - . - ~ . . - - .,_ -
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| TopicFour: October 10 - October 14:
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| ~
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| IMPLICATIONS FOR ACCIDENT MANAGEMENT resources including people, material and equipment) and management / intro #1, from sysop,10149 chars, Fri Sep trauung.
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| 26 14:45:51 1986
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| * -Communication:
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| TITLE: Paper 1 Experience in management of major accidents of all kinds continues to reinforce the vital importance of ACCIDENT MANAGEMENT AT CHERNOBYL effective communications. His includes extemal communications among accident managers, the WHAT WE CAN LEARN government, the media and the public, as well as internal communications within the plant and within the technical By J. C, Devine Jr. community. One cannot underestunate the significance of Progmm Manager this one facet of accident response.
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| Advanced LWR Program Electric Power Research Institute ne second major category of interest is on-site recovery and cleanup wodt. In this area, despite the ne accident at Chemobyl offers extraordmary evident differences in reactor design, accident specifics, and opportunities to leam and to improve upon nuclear safety cleanup approach, there is generic applicability of the in all respects. It proddes a basis in reality with which to Chemobyl experience to reactors worldwide, and supplement and adjust our analytically based assumptions undoubtedly some commonality among Chemobyl about accident management. It is important that we take experience, TMI-2 and other reactor accidents and incidents a full advantage of this opportunity.
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| Within the topic of accident management, there is a in our history. Important topics within this category include the following:
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| W wide spectrum of potential discussion areas. It is useful to think of these as comprising tisce broad categories: -Radiological Protection:
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| first, the accident response; secondly, the on-site recovery Cleaning up in the aftermath of a reactor accident (or clean-up efforts); ard thirdly, off-site decontamination. presents a unique and very challenging set of radiological Re accident resporte category covers those near-term control problems. De mnst obvious of these is that it is activities taken at the site to regain control of the necessary to manage safely pesonnel working in very situation, to protect people and the environment, and to contaminated, high radiation areas. Under such conditions, restore stability such that the longer term corrective seemingly routine matters such as work planning, nations can proceed safely. De accident response phase at protective clothing, communications, radiation Chemobyl is basically complete. It is advisable at this monitoring instruments and procedures, air breathing point to gather as much information as possible and to equipment, communications, real time dose. tracking, and analyze and extract from it conclusions which may be industrial safety all become magnified in importance and useful in preparing for possible accidents at other plants. essential to the safe completion of every job. It is It i.t important to note that, in many respects, the important to note that learning in this area also has accident response activities at Chemobyl were unique to applicability and high value to non accident conditions in the RBMK reactor and to the specific accident scenario at nuclear facilities.
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| that plaat. For that reason, applicability of the Chemobyl Compounding this problem is the fxt that the experience to other reactors around the world may be radionuclide mix generated by a nuclear accident (and somewhat limited. Nevertheless, there nre certain contributing to the high radiation fields and contamination common denominators which deserve careful attention. levels) may be quite different from that produced in normal Two of these are: reactor operations. His requires special vigilance as well as some important changes in procedures, methods and
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| -Readiness: equipment used in protecting personnel.
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| He effectiveness of any organization's--or nation's-efforts in coping with a major accident is a function of its Similarly, dealing with fuel material (including alpha emitters) rather than the fission product and activation g
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| readmess. Readiness includes thorough accident planning, materials normally encountered in operating reactors physical preparation (such as ensuring availability of presents unique cha!!enges. Use of gamma spectroscopy CHERNOBYL CONTERENCE.BY COMPtTTER - Sept.29 . Oct.17,1985 I p VI I
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| One of the conclusions from the IAEA expert meeting in . the environment, I think that fire. fighting technology is Vienna was that it is necessary to have a cen:ral authority still surprisingly primitive in many respects.
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| Q great powers to cope with an accident of this scale. Extinguishmg fires caused by severe react'or accidents
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| %ifferent Soviet bodies seem to have been well codinated .' would pose many special probleins.
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| and took to drastic measures when the public was -
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| evacuated. Dere has also been reports about a large If containment is breeched by an energetic process number of civilians who has been sent into contaminated such as steam or hydrogen explosions or high-pressure areas for decontaminationwork. melt ejection, then core materials at very high Do you consider it possible to act as swiftly and temperatures (2500 to 3000 K) could be scattered over a determined as the Soviets,if an accident of the same large area. De high temperatures could start fi es in magnitude had occured in a Westem Democracy? almost all combustible matenals, and the dispersion could Mikael Holmstrom, Science Writer, lead to very large scale fires. High levels of radiation Magazine: Ny Teknik, Stockholm, Sweden could accompany these f'ues. Although firemen are often brave, they may be very reluctant to approach a fire if doing so could lead to death from irradiation.
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| management / intro #11, from shall,1028 chars, Tue Oct 14 05:06:30 1986 Much research has already been conducted on his is a comment to message 10. combustion hazards. However,I believe that additional nere is/are comment (s) on this message. work on extinguishing fires could be very cost-beneficial.
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| There are additional comments to message 10. His research could address the following two topics: 1)
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| - - De physics and chemistry of combustible materials TITLE: EXAMPLE OF ACCIDENT MANAGEMENT including ignition and flame characteristics, emissions of IN WES'IERN DEMOCRACY. toxic gases, the best matenals for quenching flames, possible hazards in using some quenching agents for some Although not a nuclear accident, the freight train fire combustibles, and possible new chemical, physical and and explosion in Mississauga, Ontario in November 1980 mechanical concepts for extinguishing flames; and 2) is a good example of what can be achieved without a automated methods and high-technology equipment for st fighting fires. Since so many aspects of modern society O'rong ovembercentral authority.
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| 1980) 218,000 Duringover people were evacuated the an course of one day (11 could benefit from this research, I believe that the area of 120 square km. The evacuation was very efficient Chemobyl accident could provide the incentive for and smooth by all accounts, and was possible only cooperative national and intemational efforts in this area.
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| because the various agencies (fire, police, etc.) had plans, Potential supporters and users of this research include prepared in advance, which they were able to put into govemments, various industries, insurance companies, effect on a very short timescale. regulatory agencies, and even the military.
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| Dese plans included the means by which the various agencies should communicate and work together, and I don't believe that it is necessary to establish communicate with the public. All the indications are that intemational standards for operator training and the Soviets also were well prepared and it was this, rather qualification, although such standards might be useful.
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| than the fxt that they have a strong central authority that ne point I raised dealt with the hostile takeover of a enabled a quick response and evacuation. As we said in-our control room the exact opposite of beneficial accident paper above, preparedness is the key! management! I am suggesting that utility managers study their plants in terms of the capability to overide control Steven Hall room direction, if necessary, to bring the plant to a safe Safety and Reliability Directorate, UKAEA shutdown condition. Some plants may be more susceptible to hostile takeover than others. If necessary, one- way engineering changes could be considered to management /mtro #12, from mberman,4494 chars, Tue prevent deliberately harmful procedures from being Oct 1411:29:531986 initiated from the control room. Limited access and This is a comment to message 9. increased plant security measures might also be instituted.
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| Dere is/are comment (s) on this message.
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| - - You also discussed accident prevention and accident "ITILE: Accident Management - Response to Message 9 management. Clearly, accident prevention will pay the by K. Soda highest dividends in terms of public acceptance of nuclear Mr rshall Berman power, increased economic benefits from plant operation, p)
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| ( Although advances have been made in fire-fighting and decreased liability. He TMI and Chemobyl accidents technology, I do not believe that that this area has received should convince plant operators of the imponance of very sufficient rescarth attention. Considering the extent of the high safety standards, high operator skill and training, threat posed by fire to civilians, industrial structures, good management, and a solid understanding of reactor transponation, military personnel and structures, and to physics and engmeenng under normal and abnormal Page VI6 CHERNOBYL CONTERENCE BY.COMPtTTER - Sept. 29. Oct.17,1986
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| ', challenges b the area of accident management and control.
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| contribute to immobilisation (f contamination. na ~
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| This paper looks at the challenges of limiting the spread movements of wild animals could hinder comaminanon of radiation and of cleaning up off-site contammation in ' control, particularly if habitats are destroyed by order to limit long-tem effects. The speed with which the Soviet authorities have orgarused large scale decontamination work.
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| g decontamination and civil engineering works is most DECONTAMINATION. Decontamination, where impressive, and points to a large degree of preparedness possible,is obviously the best method of contamination and co-operation between agencies. control Working "from dirty to clean", the need for The control of off-site contamination depends on three personnel access to clean areas and prevention of re-principles: Immobilisation, Decontamination and contamination are principles that need to be taken into Monitoring.His paper examines these principles in the account in formulating a decontamination strategy.
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| light of Chemobyl experience.
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| In a 30 km radius around the plant the measures taken a) BUILDINGS, ROADS AND VEHICLES. De use of are appropnate to an agricultural region in spring / sum ner, decontamination sclutions for washing by jets or by hand.
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| Another type of land use in another season might and the use of remevable polymer coatings (as at TMI) are necessitate different measures. well-known and well-tried technologies, albeit on a small scale.
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| IMMOBILISATION. The immobilisation of radionuclides is vital for control of contamination where b) SOIL. Decontamination on-site has been achieved at decontamination is impossible or incomplete. First, Chemobyl largely by soil removal and storage with funher release from the source must be prevented. Since replacement either with fresh soil or concrete. Methods removal of the core is impracticable (in contrast to TMI) have been proposed to remove radionuclides from soil by this is being achieved at Chernobyl by entombment of the chemical scrubbing but this is only practicable for small damaged rector, and site decontamination. Den, areas. Removal of radionuclides by irrigating the soil with redistribution must be controlled : complexing agents is possible for larger areas but has the effect of moving the contamination into ground water.
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| i) FROM SOIL. De main method used around Plant varieties with large root uptakes of Cs and Sr could Chernobyl has been to treat soil with dust supr ession be considered in this respect, since barvesting and compounds to prevent resuspension. Ploughing in destruction would have the effect of soil decontamination.
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| g contamination using deep-digging ploughs has been tried Unstable ground covers such as sand or snow pose a experimentally Bis method reduces ground shine by a particularly sericus problem.
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| factor of 515 but may be only moderately successfulin preventing resuspension (10% contamination is left on the MONITORINO. Accurate and widespread monitorin; l1 surface), and has the disadvantage of encouraging entry of necessary to provide informa:ien for the formuladon of contaminants into underground water. decontamination strategies, both in quantifying the levels of contamination and in assessing its movement.
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| ii) IN SURFACE AND UNDERGROUND WATER. In Continual monitoring over many months, and perhaps order t'o prevent contamination entering the Pripyat' river, years, is the only way of ensuring that decontamination large scale civil engineering work has been required to and immobilisation measeres are effective, and that redirect and treat surface water, and to lower the water stability at a low dose leve! has been achieved. His table.
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| information is required by thc3e who have to make decisions about repopulation, replanting and other returns lii) ON PERSONNEIJVEHICLES. His can only be to normallife.
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| controlled by zoning with strict control of movements. At Chernobyl, personnel are trans-shipped and vehicles CONCLUSIONS. Accident management on this scale decontaminated at zone boundaries. demands rapid actio1, cooperation between a large number of national and intemational agencies, and the anmediate iv) ON PLANTS AND SEEDS. His necessitates availability of diverse commodities (concrete, reagents, harvesting and destruction of crops and grass. Treatment of measuring equipment). Preparedness demands planning, soil with time inhibits root uptake of Cs and Sr in future Effective measures, usable on a large scale in various crops, which must be chosen to have low root uptake. In conditions, mttst be the aim of research.
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| the Ukrame, trees are a particular problem because of their part in the ecosystem (moisture conservation). Fire is the -- - --
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| most likely cause of redistribution of radionuclides fixed management /mtro #4, from mberman, 7097 chars. Fri in trees and forest litter and so fire prevention is the Oct 1010M01 1986 easiest remedy. - - - - - - - - -
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| v) ON ANIMALS. Prophylactics such as bentonite limit TITLE: IMPLICATIONS OF CHERNOBYL FOR Cs uptake from feed and, by fixing the activity in dung, ACCIDENT MANAGEMENT CllERNOBYL CONFERENCE.BY.COMPtTTER Sept.29. Ott.17,1986 Page VI 3
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| taken under circumstances which fell well under made of use of respirators (SCBA), and dosimiters, established guides in this area. Yet these actions, _ particularly PADI's (Personal Alann Dosimiters), which
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| -m whether witholding crops / milk from use or evacuatmg all we would routinely use before sendmg personnel into such
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| ( ')or selected segments of a population, cany their own an environment. I also do not recall mention being made costs. 'Ihese costs range from economic and social of surveys prior to sending inThe fire fighters. The dislocations to psychological trauma to actual risk of implications are that extingutshmg the fires was injury or death during evacuations or harm from such considered of absolute priority. Some mention was made prophylatic treatments as KI. of concem for other combustibles. I2t me propose some discussion questions:
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| It seems to me that the guidance for levels at which
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| : 1) Under what circumstances does one risk the lives protective actions are launched needs some fresh of firefighters, eg. not take time to dress and dosimiter perspectives in terms of the risks of the actions properly?
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| themselves, perhaps in terms of the ahematives available , 2) What are the implication: for mul.iple unit t,ites?
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| in particular circumstances. In any event, we ought to be focusing our post-Chemobyl accident management -
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| leaming on the real needs, rather than postmg low- management / intro #19, from shall,1400 chars, Wed Oct probability
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| * boogie-men" as valuable objectives for 15 10:47:33 1986 funhet study. 'Ihis is a comment to message 18.
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| M I Goldman, NUS Corp FIRE FIGHTING AND RISK TO FIRE FIGHTERS
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| 'Ihis note applies equally to comment #12. SF Hall Safety & Reliability Directorate, UKAEA management /mtro #16hm each,160 chars, Tue Oct From the account of the accident given in Vienna it 14 16:46:26 1986 sppears that the response to the fire by firemen from the
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| 'Ihis is a comment to message 10. towns of Pripyat and Chemobyl was quite rapid and it may have been that the speed of action precluded concem It may also be necessary to have a central authority with for personnel safety. Also in this case it is unlikely that 9 great powers and limited public involvement to have an respirators would have provided much protection since the accident of this magnitude in the first place! ulk of the dose came from directradntion from core matenals rather than airbome contamination.
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| management / intro #17, from 11each,734 chars, Tue Oct How much protection and real-time monitoring could be 14 16:53:48 1986 affsded fire-fighters on a short timescale in a nuclear "Ihis is a comment to message 11. accident is a question that ought to be addressed for all nuclear installations. It is certamly a question which has
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| 'Ihe soviets admitted in Vienna that their emergency caused a great deal of worry to the fire brigade trade union plans were inadequate for the situation that occured They in the UK since Chemobyl, and led that union to take a had not imagined an accident of this magnitude. While strongly antinuclear stance at the recent Labour pany their response does indeed appear to have been very good convention. In an emergency, as we saw at Chernobyl, given the circumstances, it's difficult to say how good and ' people are capable of showing great heroism; however, if a similar response would have occured elsewhere.
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| our emergency planning should not rely on it.
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| Cenamly in countries with more free press and commenication, and with more individual automobiles, Obviously, as has been stated by several contributers, the problem would have been more difIicult. It is difficult robotic fire-fighting equipment is the answer but in the to imagine effectively implementing a sheltering decision, interim those involved in emergency planning should for example, in an event of this magnitude. . make this sort of question a priority.
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| Thus, I support the conclusion that preparedness is the key,in spite of some different interpretations of the Soviet response. management /mtro #20, from shall,427 chars, Wed Oct 15 10:57:15 1986 management / intro #18, from 11each,757 chars, Tue Oct EVACUATION - HOW DO YOU DECIDE?
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| 4 17:01:19 1986 is a comment to message 12. SF Hall Safety & Reliability Directorate, UKAEA It appears as though the protection of the firemen was not given high priority. In particular, little mention is Do any panicipants have views on the following -
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| Page VI-8
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| : CHERNOBYL CONI'ERENCE.BY-COMPUTER - Sept. 29. Oct.17,1986
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| O Control of Plant Operations - - - - - - - -
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| management /mtro #8, from psviatoslavskyx,121 chars, As a consequence of the accidents at TMi and Fri Oct 1014:37:44 1986 Chernobyl and the contributions due to operator error, we can hope that plant operators will be much more safety his is a comment to message 7.
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| ~ g conscious in the future. However, a different aspect of Sorry for the errors, ne statement should read, " filtered accident management needs to be considered if plant by a few feet of soil."
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| operations are seized by hostile groups (terronsts, Pete Sviatosbysky disgruntled or suicidal employees, etc.). Although measures should clearly be taken to pruent hostile takeovers, it might be prudent for plant managers to have management /mtro #9, from ksoda,1605 chars, Sun Oct avaibble to them measures to manage and terminate 12 06:37:46 1986 accidents tmder such conditions. His is a comment to message 4 Here is/are comment (s) on this message.
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| In conclusion, the approach to reactor safety pnmarily involves accident prevention and containment. Accident Whenever we discuss " accident management" we should management, however, involves the minimization of discuss "mcident prevention" with an equal weight. As consequerces. Dere is much that could be leamed from one of exmtries which depend on nuclear energy to Chernobyl regarding accident management. It would be Produce electricity, Japan continues to construct nu: lear wise to consider how we would respond to an accident of Power phnts although with slower pace.
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| the same magnitude. If tliere are important questions that require some answers,it would be prudent to begin to However the Chernobyl-4 accident had an impact on procure the necessary information now. Japanese public perception of reactor safety, perhaps the impact was less severe than some of European countries.
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| Neverthless, the accident gave us a good opportunity to management / intro #5, imm psviatosbyskyx,376 chars, review safety issues in our country as well. Here are two FriOct 1010:13:041986 different concems among publics. One is accident His is a comment u> message 3. management and the other is accident prevention.
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| Dere is/are comment (s) on this message. Residents near a nuclear power plant which was already Comment on paper #2.
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| built are more concerned about accident management, while residents near a power plant which are in planning g
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| stage are concerened about accident prevention. If we It was my understanding that, depending on the type fo emphasize too much on our readmess to cope with a soil, particulate contamination is readily filtered by a few severe accidcat and a well defirci accident management, of soil and that runoffinto streams and rivers is the major PCOP l c tend to believe that a severe accident is a reality, concem. Any comments on this by conference participants Derefore our first priority to convince public of safety of would be appreciated. a nuclect reactor is to prevent a severe accident and to let public believe the safety of a nuclear reactor. Then as a Pete Sviatoslavsky backup system, accident management should be prepared.
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| WPSC Green Bay WI Questions to Dr. Berman. Do you see needs to develop new tools or new considerations on fire fighting management /mtro #6, fmm psviatoslavskyx,100 chars, techniques after the Chemobyl-4 accident? Rebting to FriOct 1010:28:261986 your comments on the hostile group etc., perhaps we need his is a comment to message 5.
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| to establish a sort of an intemational operator training or There are additional comments to mesage 5. qualification throughout the world.
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| My Comment #5 is refering to the contamination of K. Soda, JAERI, Japan.
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| ] ground water. Read:
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| Pete Sviatoslavsky management /mtro #10, from mholmstrom,864 chars, Mon Oct 1311:00:231986 management /mtro #7, from jmaclellan,29 chars, Fri Oct Here is/are comment (s) on this message.
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| 10 13:00:34 1986 His is a comment to message 5.
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| TrI'LE: DOES THE MANAGEMENT OF A Here is/are comment (s) on this message.
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| NUCLEAR ACCIDENTREQUIRE A STRONG CENTRAL STATE?
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| Filtered by a few ? of soil?
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| TO ALL PARTICIPANTS CHERNOBYI CONTERENCE BY COMPLTER - Sept.29. Oct.17,1986 Page Vt s
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| . COMMENT ON J. ROYEN COMMENT #11 . Mr. Tapia should be aware of the exchanges underway in
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| $1EVEN C. SHOLLY, MHB TECHNICAL the U.S. between the NRC (Robert Bemero, et al.) and the
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| : ASSOCIATES BWR Owners Groups concenung possible. design and operational changes for Mark I plants to increase their Monsieur Royen may feel free to call the Chernobyl capability to resist early failure in severe accidents. I containment whatever he wishes. 'Ihe fact remams that suggest Mr. Tapia contact NRC regardmg the details. I
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| ' the Chernobyl ennramment was d%=d around a design would be pleased to discuss Mark I containment basis accident that is nearly identical to that assumed for vulnerabilities in more detail via a=-+g= E-? should Western LWRs. - Of course, a quite different approach was Mr.Tapid (or others) desire. ;
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| taken, one which resulted in a contamment which is ,
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| poorly suited,if at all, to preventing a substantial QUESTION FOR L. HOEGBERG FROM S. SHOLLY radiological release in the event of an accident beyond the . .
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| design basis. C=e.-J..g whether this makes the Are the Swedish BWRs permitted to de-inert their
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| .Chernobyl "contamment" a " partial containment" or a contamments while at power? U.S. reactors are permitted l "g=-_'-:-:.wtainment", there is a saying in my native by NRC r M- to de. inert 24 hours prior to Pennsylvania which I will paraphrase - if it walks like a shutdown for refueling or any other major outage, and ,
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| duck and. talks like a dsk, there is a very high conditional may remam de- inened at power during the first 24 hours l
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| probability that itis a duck. of operation following such an outage. The Lirnenck PRA (and the subsequent review by Brookhaven National In addition, I think that most observers can readily Laboratory) aw=wd that there was a 1% chance of early draw the distmetion between the Chemobyl containment contamment failure due to hydrogen burn / detonation approach and that adopted for Western reactors. If, resulting from this practice. I would add that this practice however, the Chemobyl contamment is a is being re- examb4 in the discussions in the U.S.
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| - =g_-a. .=:. .7_ =t", then I submit that the same could conceming possible safety improvernents for Mark I 4
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| be said - with considerable justificanon - for Mark I and containments.
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| Mark II BWR contamments and the ice condenser PWR contamment. None of the latter perform very well for a QUERY IOR MICHAEL HUTCHERSON,FAI range of accident scenancs, although each exhibits some S'IEVEN C. SHOLLY, MHB TECHNICAL tainment capabilities for cenain severe accident . ASSOCIATES l I may have nussed your response to my containment RESPONSE TO COMMENT #14 BY A. BRACHET paper conceming steam explosions. Could you possibly AND H.GUMBAIL , re-transmit or send a copy by mail? I am most interested STEVEN C. SHOLLY, MHB TECHNICAL in FAI's views on steam explosions post-Chemobyl.
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| ASSOCIAM RESPONSE TO COMMENT #34 BY S. HALL, SRD, The 200 MJ figure I understand to have been UKAEA
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| ] calculated by French participants in the IAEA meeting; I STEVEN C. SHOLLY, MHB TECHNICAL j am unsure whether this figure was for the thermal release ASSOCIATES or the kmett energy imparted to the structures above the.
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| core. In reganh to the 320,000 MJ figure, this was a Mr. Hall observes that a very small hydrogen thermal energy release calculated by NRC sources; I would explosion would be sufficient to destroy the comparatively prefer that these gentlemen step forward with their weak structure above the operating floor at Chernobyl. I calculational method and results. Indeed, I would be most would agree, and further observe that the same is true of interested in any refinements that have taken place since I BWR Mark I and Mark II contamments. Has anyone done spoke to them, since their calculation was preliminary and any calculations as to what structural damage could be ongoing. expected from hydrogen burn / detonation in the reactor
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| .: buildings of Mark I and Mark II facilities?
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| RESPONSE TO COMMENT #16 BY J.TAPIA STEVEN C. SHOLLY, MHB TECHNICAL RESPONSE TO COMMENT #41 BY P.
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| ASSOCIATES SVIATOSLAVSKY STEVEN C. SHOLLY, MHB TECHNICAL Merk I contamments are notoriously ill-equipped to ASSOCIATES respond to the containment loadings likely to be imparted j a vanety of severe accidents. Owing to their small free You raise an interesting aspect of the RBMK design
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| 'lumes, Mark I containments are particularly susceptible philosophy. Does anyone have any information to early failure under any impulsive loadmgs (such as conceming the design bases for external events for RBMK hydmgen burns when the containment is de.inerted or such reactors? I would be particularly interested in seismic, as high pressure melt ejection resulting in direct heatmg). aircraft crash, wind, and snow loadmgs. 1 Pase IV.14 CHERNOBYL CONFERENCE.BY. COMPUTER - Sept. 29 . Oct.17,1986
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| pool. As a consequence, high energetic pressure peaks are have been in the building above the operating face of the expected for those cases where the coherent molten fuel reactor after the ficor had failed due to the earlier mass isof the order of 10 metric tons. To my explosion. If this is so, then the geometry would make a understandmg, in the Chemobyl accident the power excursion has rised rapidly fuel temperatures associated detonation vutually impossible to achieve. However, it is my opinion that a deflagration of the order of that that g with transient fission product release and partly fuel occured at TMI would be sufficient to destroy the vaporization which together have caused fuel pin comparitively week structure above the operating floor if overpressurization and clad ruptare. Almost it were still intact after the initial explosion.
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| simultaneously finely fragmented, overheated fuel was ejected into the pressunzed coolant channel where the fragments interacted with water and steam. These spacially containments /mtro #35, from shall,1153 chars, Tue Oct distributed events will have extended the load period of the 14 12:13:11 1986 core and increased the damage energy. This is a comment to message 24 In order to r. void misunderstanding, it seems to me that TITLE: DEFINITION OF CONTAINMENT in Chemoby? a fuel-coolant (or water) -interaction (in the Fast Breeder Accident Analysis well known as FCI) has It is clear that the Chemobyl ' containment' is designed occured rather than a steam explosion as Symyd in on the same basis as any western LWR, i.e it is desigr.ed LWR safety investigations. to withstand the pressures generated by a 200% guillotme B. Kuczera break in the largest primary pipe. (The possible exception to this is that it is not clear whether the refuelling hall i i i i floor / reactor roof at Chemobyl is designed for this containments /mtro #33, from lleach,798 chars, Fri Oct pressure load - does anyone have any infor- mation about 10 15:26:10 1986 this?) As pointed out by EnnoHicken, the main question This is a comment to message 31.
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| concems the definition (choice?) of DBA. Margaret Ryan
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| (#28) asks what is the fastest, most powerful accident LWR containments could confront and whether this Brian, that was my message on tube rupture accident forms part of the design basis. This is a question propogation. We have a model for the N Reactor, which is which deserves attention but it must be put in the context also a pressure tube, graphite moderated reactor. It uses the RELAP5 code to generate loads on the graphite of frequency of cccurence. What Chemobyl might teach is that the choice of DBA should be made after an analysis resulting from tube rupture, and calculates strain on of the sort ofloadings that migh occur over a wide range
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| ; adjacent tubes. It's validated based on rupture tests of fault conditions, rather than assuming that what is a l performed at Hanford. At N Reactor, void space was reasonab!c DDA for one reactor is necessarily appropriate I designed into the graphite moderator to vent the steam and for another.
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| l reduce the load transmission. (Also results in negative j void coefficent of reactivity .not sure which came first Steven Hall but now we're sure glad about the later!) Anyhow, we Safety and Reliability Directorate, UKAEA.
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| have had Impell modify this model for the RBMK, and the calculated loading exceeds our criteria for rupture propogation. If you need more info please contact me by containments / intro #36, from shall,1210 chars, Tue Oct mail. 14 12:17:47 1986 l Larry Leach (aka "llcach") This is a comment to message 32.
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| TITLE: STEAM EXPLOSIONS containments /mtro #34, from shall,901 chars, Tue Oct 14 12:07:56 1986 Firstly, I would like to say that I agree with Marshall This is a comment to message 10.
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| Berman's comments (#27).
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| 'Ihue is/are comment (s) on this message.
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| My feeling is that it is perhaps premature to try and draw TITLE: HYDROGEN EFFECTS a distinction between the rapid steam generation event at Chemobyl and steam explosions as normally considered in As Marshall Berman points out, large quantities of LWR safety assessments. It is true that if the pressure hydrogen can be generated on a very short timescale if the pulse at Chernobyl were a result of solid fuel metal being oxidised is molten (or dispersed in some other fragmentation and dispersal into water, then the event I way). However, it is unlikely that a hydrogen explosion would differ from a steam explosion as usually understood
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| ; could have contributed * , the destruction of the co e since because the fuel would not be molten, as has been said the hydrogen generatim under these circumstances would above. However, although there is experimental evidence preclude oxygen. If a hydrogen explosion occurred, it must of solid fuel fragmentation, the occurence of this in CHERNOBYL CONFERENCE.BY-COMPITTER - Sept.29 Oct.17,1986 Page IV.tt
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| 1 l
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| management actions taken by govemment could increase sufficiently motivated saboteur. M. Goldman on the other rather than decrease the risk to the public. hand (message 15) believes that the seizing of plani operations by hostile groups is a " fringe effect[s] of I know nothing about the comparative efficxy of vanishingly low probability." How were such low hvacuation vs sheltering / respiratory protection. What I probabilities calculated? Given that " success" is trivially would suggest, however,is that the controversy embodied simplistic, the occurrence woufd depend only on in the above concems needs to be addressed and resolved opportunity and motivation. I think that it would be quite BEFORE the next accident occurs. My paper and those of difficult to quantify the probability of these two factors many others supported the accident,tranagement concept coming together. I would be very skeptical about any of being prepared, and knowing the appropriate actions to " human factors" analysis of this probability. I believe take. Disagreements as fundamental as evacuation vs that it is in the utilities' best interest to assess the sheltering should not be argued DURING an accident. vulnerability of their plants, and to take appropriate measures, especially if such measures could significantly Mr. Sholly believes that insider sabotage causing ccre reduce accident consequences, regardless of " probabilities."
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| melt would be a trivially simplistic proposition for a END OF ACCIDENT MANAGEMENTCONFERENCE p.,
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| V e
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| k V
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| Page VI.10 CHERNOBYL CONFERENCE.BY.COMPLTER - Sept. 29. Oct.17,1986
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| conditions. Accident management, however,is more like Good accident management requires: 1) an accurate insurance. Having taken all the appropriate steps to knowledge of the phenomena which may occur and their prevent an accident, we must still must be prepared for its consequences; 2) an agreement by utiHty, govemment and occunence. He public will accept nuclear power when they realize that plants are operated with the safest possible procedures, and that accidents,if they occur, will regulatory agency to take specified actions based on dermed accident indicators; and 3) a belief by the press and h
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| public that all three organizations are telling the truth, and pose hazards no greater, and generally much less than from anempting to protect the public. HiI was an example of other modern technologies. the wrong way to manage an accident. If we work very hard to achieve the three above requirements, accident consequences will be minimized or eliminated. No strong management / intro #13, from mberman,3297 chars, Tue central authority will ever be needed.
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| Oct 1411:35:071986 This is a comment to message 10.
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| Here are additional comments to message 10. management /mtro #14, from abrxhet,492 chars, Tue Oct 1411:39:061986 TITLE: Accident Management - Comment on Message 10 by M. Holmstrom TITLE: General question for all participants and Marshall Berman -
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| specially for electricity producers ones ,from aA
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| , Mr. Holmstrom asked the question whether BRACHET AND B NOC management of nuclear accidents required a strong central state. My answer is that nothing in society requires a Following chemobyl accident,have you initiated studies strong central state. The rapid responsc of an aatnoritarian and what kind of studies, dealing with piotected means state sometimes generates awe among those who live in and/or roboted means in view to work near the accidented free societies. My advice is to reread the history books of reactor and for operator's protection of the same site this century and quickly abandon such foolish notions. reactors, specialy whit the objective to maintain the reactors in state of safe shut down?
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| Dictatorships act quickly because they do not need to consult with or consider the wishes of the people or their A Brachet and B Noc representatives. However, the correctness of their actions Electricite de France is ultimately determined by the results. If the Soviets had (or have) taken actions which were wrong in retrospect, h then the centrnh7ntion of power was a negative factor. management /mtro #15, from mgoldman,2032 chars,
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| , The evacuation of the people from Pripyat was delayed. Tue Oct 1411:46:25 1986 ad an even longer delay was involved in evacuating his is a comment to message 12.
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| others in the 30 km zone. This may or may not have Here are additional comments to message 12.
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| been the aappropriate action.
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| His is a comment on Paper #4 Holmstrom seems to be implying that civilians were l ordered into contaminated areas by the Soviets at great One of our major concems in leaming from the personal risk. I'm not sure that this is so, but surely he Chemobyl accident must be to maintain a sense of can't be recommending this for Westem countries. Many perspective and to resist the temptation to translate that measures are available for decontamination that do not accident to potential accidents in U.S. reactors without l involve high risks: using robots, limiting exposure time, considering the results of extensive evaluations which
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| ) special equipment, etc. have already been performed. In this context,I find it l somewhat disturbing to note concems about " dispersal of l Westem democracies are quite capable of taking fast molten fuel and claddmg outside containment" and " plant l action when needed. This has often been demonstrated in operations.. seized by hostile groups", concerns which are natural disasters such as canhquakes or hurricanes. He focussed on fringe effects of vanishingly low probability, key is being prepared. American response to hurricanes Certamly, we have more significant areas in which to and floods is frequently fast and effective because all focus our attention insofar as accident management is parties are prepared, and the public believes and acts on concemed, a number of which are identified in Jack information it receives. De TMI accident was a case in Devine's paper.
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| which some of the worst aspects of accident management dominated. The public was confused by the chaos and One such area that strikes me as important, and contradictions which emanated from GPU, the NRC, the press and TV, and the govemment. The relationships unresolved,is these thatAsofTMI circumstances. effective protection demonstrated here, andaction guides among these groups has sometimes been adversanal in the much of the behavior in Europe following Chemobyl, so-past. Perhaps the Chernobyl accident can instill more of a called " protective actions' were implemented more on spirit of cooperation. political than on radiological grounds, i.e., actions were CHERNOBY1. CONFERENCE.BY. COMP 17FER - Sept.29 . Oct.17,1986 Page VI.7
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| i v .
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| , quesnon: In an accident simanon, in order to decide that RISK by posing the followmg questions:
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| whether evacuanon is necessary and when, how much -
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| : 1. Did the acculent at Chernobyl 4, because of O rehance much on direct should be placed measurement of radiationon levels computerin the modelling radioactive and how releases, interfent.with the c-;-- =M of other
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| 'V field? reactors on the site?
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| : 2. Wha: kind of difficulty and costs were encountered to
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| ;. management / intro #21, from mgoldman,1562 chars, E c 2--inate other reactors on-site, in order to provide ~
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| Wed Oct 15 21:22:201986 safe unprotected access for plant personnel?
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| nis.is a comment to message 20. -
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| : 3. Was it costly to decontammate on-site units which are under construction?
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| De decision as to the necessity for evacuation under accident cucumstances is always going to depend upon the 4. Was it iwt.nay to decontaminate the interiors /
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| parucular situation. It seems obvious that the best data exteriors or both of on-site structures?
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| would be that obtamed from measuremeents in the field, although such measurements im ily reflect only what 5. What provisions have been made to preclude the
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| ,;~ has prr-tal up to the point in time at which the further on-site spread of radiation from Chemobyl 4 to
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| , measurements are made -- they cannot include future other on-site reactors and structures?
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| projections which are inherent in modelling, whether by computer rv slide rule (if any still remember those 6. Has on-site decontamination produced liquid and solid antiques!). Computer modelling on the other hand waste? How has this been disposed of?
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| provides a basis for projecting the future course of accident consequences, given the validity of the input data with 7. What techniques were used to remove contamination !
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| respect to source terms and meteorologicalinformation, from various structures?
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| and a mathemancally reasonable representation of the transport and dose relationships. 8. Was a priority list for decontammation established?
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| , (For example control room first, equipment cubicals The degree of reliance to be placed on one or another of second, etc.)
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| , these tools would, it seems to me, be determined at the
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| ' ~
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| time by the nature of the release (i.e., monitored or not, 9. Were there shared systems between Chemobyl 4 and puff or steady), the quality and quantity of monitoring data other units on-site which led to damage or contaminadon from the field, the nature of the meteorological condition to adjacent structures?
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| at the time with respect to the model capabilities (i.e.,
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| calm winds with vanable direction indicated, precipitation scattered in time and space, direction and speed shear with management / intro #23, from mberman,2515 chars, height, etc.), and the magnitude of measured or projected Mon Oct 2013:30:391986 doses relative to promulgated action levels, among other factors. TITLE: Comments on Accident Management I- Probably among the more certam of the conditions at the TITLE: COMMENTS ON EVACUATION AND
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| ! timg of an accident is our inability to predict them in CON'IROL-ROOM TAKEOVER L advance!
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| Marshall Bernan Mort Goldman, NUS Corp Sandia National Laboratories Steven Sholly (Containments Conference, message management / intro #22, from ani,1444 chars, nu Oct 44) says that much work has been done on when and why 16 13:10:09 1986 to initiate evacuation. However, he raises the concem that i
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| His is a comment to message 1. evacuations may be initiated prematurely, or inappropnately. John Matuszek of the New York TITLE: IMPLICATIONS OF THE CHERNOBYL Department of Health (Containments Conference, message ACCIDENT AT MULTI-UNIT SITES 45) concurs that evacuation might be ordered more for political than heahh reasons. Both of these messages De accident at Chemoby! can provide a worst. case imply that sheltering and respiratory protection could be O swument of the RISK involved in the operation of more effective responses.
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| j multi-unit sites when one of the units suffers a very
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| ; serious reactor accident with significant releases to the In spite of the " work" already done on evacuation, the environment. ANI would like to initiate a discussion of concems of these two gentlemen appear to be that accident CHERNOBYL CONFERENCE.BY.COMPITTER - Sept.29 . Oct.17,19s6 Page VI.9 i
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| standards. Those efforts need to be supplemented by an debt has come to market since mid-June,1986, which improvement of the national and intemational regimes of suggests an aggregate increase in cost of capital to date of compensation for nuclear damage. Victims of nuclear about $30 million. ,,
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| accidents should be entitled to claim compensation directly against the operator of the nuclear installation wherever it Emergency Plannmg Concerns h is situated. Minimum standards ofliability and equal treatment of all victims have to be guaranteed. He State and local opposition to participation in emergency existing intemational instruments on nuclear liability, planning has caused the owners' target in-service dates for namely the Paris and the Vienna Conventions, provide for several nuclear units to slip. The esumated cost increases an adequate liability system, provided the maximum for each additional month these units are not commercial amounts of liability will be raised. An appeal to all States are as follows:
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| to accede either the Paris or the Vienna Convention and to negotiate about improving these instruments would be a REACTOR LICENSEE MONTHLY COST desirable outcome of the IAEA Conference. Shoreham long Island Lighting Co. $30mm Seabrook Public Service of NH $50mm Perry 1 Cleveland Electric Illum. $60mm finance /mtro #2, from sysop 9549 chars, Fri Sep 26 14:48:15 1986 If commercial operation of each of these units is delayed by 6 months, the aggregate incremental costs due at least TITLE: Paper 2 in part to Chemobyl would be about $850 million. Keep Some FinancialImplications of the in mind that delays at these plants could be significantly Chernobyl Accident for longer than 6 months, and also that other reactors could be U.S. Electric Utility Companies effected.
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| By Paul C. Parshley, Vice President Donaldson, Lufkin & Jenreue Reactor Containment Issues While the financialimplications of the Chemobyl For several years, operating reactors with General accident for U.S. electric utility companies defy precise Electric Mark-1 containments have been the focus of NRC measurement, incremental costs attributable to that research because of their apparently high probability of accident are likely to be substantial. His paper identifies containment failure during a large nuclear accident. Quite several ways in which the Chernobyl accident has, or conceivably the Chemobyl accident will tend to push could increase the cost of commercial nuclear power in the NRC staff to require licensees'to take certain steps to U.S. He list below is intended to be illustrative rather upgrade the Mark l's ability to contain some smaller than exhaustive. Also,I am not suggesting that accidents. He average retrofit cost per reactor likely will Chemobyl is the sole cause of these higher costs, but it be on the order of $3 million for upgrades in the may have tipped the balance in the direction of tougher following areas- dry well spray installation; back-up regulation. Finally, my projections of specific cost water sources for spraying; containment venting, core impacts are intended to depict orders of magnitude and not debris control; and, training and procedures. The
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| : precise amounts, combined costs, tehrefore, for the 24 Mark-1 reactors I
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| would be about $75 million.
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| Institutional Investor Rextions to Chemobyl NCR Staff Regulation of Operating Reactors will be In early July,1986, we polled our key institutional Tougher and More Costly clients to get a sense of the extent to which Chemobyl had changed their perceptions of the riskiness of Several commercial reactors have been removed from investments in electric companies which own nuclear service for undetermined periods of time. Davis.Besse, plants. 35% of the respondees said nuclear utilities now Rancho Seco, and Fort St. Vrain, were shutdown prior to l
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| seem "significantly more risky" than non-nuclear utilities; Chemobyl. NRC's decision to allow these reactors to and, another 45% now regard nuclear utilities as retum to service could be delayed in part due to "somewhat more risky." These investor perceptions Chemobyl. While, once again, the impact of Chernobyl suggest nuclear utilities now might have to pay a is intangible, each month of outage has the following "Chemc' I risk premium" in order to access capital approxunate costs:
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| l markets. If the Chemobyl risk premium were 10 basis points (which I suspect is a reasonable assumption), a REACTOR LICENSEE MONTHLY COST nuclear utility coming to market with a new offering of SftJO million in senior debt now would pay $1 million Davis-Beese Toledo Edison Rancho Seco Sacramento Muni Util Dist $8mm
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| $8mm g more than before the accident in order to attract Ft.St Vrain Public Service of Colo. $8mm institutional lenders. About 53 billion in nuclear utility hge VII 2 CHERNOBYL CONFERENCE.BY-COMPtTTER - Sept. 29 Oct.17,1986 l
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| ?. h l,
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| = TopicFive: October 15 - October 17:
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| }
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| ~
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| FINANCIAL IMPLICATIONS Result: Dere seems to be strong evidence that the Tc r.wStro #1, from sysop,5245 chars, Fri Sep 26 USSR acted wrongfully by violaung both intemadonal 14:47:03 1986 obliganons, and therefore is liable under public international law to compensate damage in other States TrrLE: Paper 1 ,. caused by the Chemobyl accident. Since the USSR has not accepted the obligatoryjurisdiction of the International Financial and Liability Aspects Court of Justice, negotiations on obtaining compensation of the Chemobyl Accident By Dr.Norbert Pelzer will be ram-i.
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| University of Got:imten 3. In Westem European countries the Paris Convention '
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| on Third Party Liability in the Field of Nuclear Energy
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| : 1. De Chemobyl accident if April 26,1986, proved and the Brussels Supplementary Convention to the Paris the assessment to be true that euclear incidents may cause Convention provide for a widely harmonized basis for widespread and long-range radi active pollution, irKluding compensation of nuclear damage. De Paris Convention transboundary effects. Damage to man and property was establishes strict liability for the operator of a nuclear caused in the USSR, Various European countries suffered mstallation and grants to the victim of a nuclear incident damage to the environment from the radioactive direct claims under civil law agamst the operator, emissions. Agricultural products were contammated, irrespective of which member State the installation is importation and exportation of fmits and vegetables were situated in. De Brussels Supplc;r-,imy Convention hampered. Seasonal farm workers lost their jcbs. provides for additional State compensation in case the Tourism industry speciahzed on East European countries damage exceeds the maximum liability amount of the
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| , lost its clientele. In the Federal Republic of Germany, operator pursuant to the Paris Convention.
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| e.g., the damage amounted to approximately half a billion .
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| Doutsche Mark.
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| Whde the Paris Convention covers the Western European States, including Greece and Turkey, the Vicnna His situation raises the question whether and to what Convention on Civil Liability for Nuclear Damage extent the USSR and the operator of the Chemobyl provides for a liability regime on a worldwide range. His nuclear power plant are liable, under public intemtional Convention, however, has only been accepted by 10 law and under civilliability law respectively, for damage States, most of them developing countries, caused by the accident.
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| The USSR - like the USA, Canada, and Japan - is
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| : 2. De U.S.-Canad.an Trail-Smolter Arbitral Tribunal neither a member of the Paris nor of the Vienna (1941) stated that "no State has the right to use or to Convention. Dat means that a foreign victim has to sue permit the use of its territory in such a manner as to create under national law, which causes great practical and legal injury in or to the territory of another or the properties difficulty. Generally, the victim has the chcice to raise a or persons therein, when the case is of serious claim against the Soviet operator either at a court of his consequence and the injury is established by clear and country or at the Soviet court competent for Chemobyl.
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| convincing evidence." Today, this statement is generally According to the rules of Private Intemational Law the accepted as a rule of intemational custom. Its breach judge will decide which national law is applicable: that of i entails State responsibility under public intemadonal law. the victim or that of the operator. Dis procedure bears considerable uncertamty for the claimant. Moreover, it is Here is another international customary obligation '
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| not at all sure whether the Soviet court will admit him as relevant to Chemobyl: In emergerr.ies involving the risk a clamunt, and, in case he sues at a court of his own
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| ; of transfrontier damage the State of origin is obliged to country, whether the judgment will be enforced in the inform other States in time in order to enable them to take USSR.
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| preventive measures. De USSR did not fulfdl this international obligation to timely information and 4. At IAEA's Special General Conference from O notification of the accident, thus hindering States from September 24 to 26,1986, member States will discuss
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| ; minimizing the extent of damage to their territories.
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| the possibilities of improving nuclear safety, e.g. by establishing internationally binding nuc! car safety CHERNOBYI, CONFERENCE.BY. COMP 1,TER - Sept.29 . Oct.17,1986 Page VII.I 1
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| 1
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| -- - - . --- , c- . - , , . , - - - --- , - - . , - - _ _ . , - . - - , - - . - - , . . . - - - - , . - - -
| |
| | |
| . . = . . - . ... . . - . -- . _ _ _ _
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| h ;,
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| * co - ,
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| 10 (1
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| )
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| .Q .
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| i l
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| l l
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| PROPOSED BWR SEVERE ACCIDENT CONTAINMENT REQUIREMENTS I
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| 4 O
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| R. M. seRNER0
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| ; DECEMBER 9, 1986 o
| |
| O e
| |
| S
| |
| . - - - - - .. . - . _ _ _ _ _ _ . - - - - - , . . - - - . - - . . , . . ~ . . _ , - . - - - - ..._------ .,,. _.. _, .. .-,,-- -., --- _ _____- _ _ , _ _ . . - -
| |
| | |
| 3
| |
| .. 1 4 -
| |
| 4
| |
| ~
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| NRC SEVERE ACCIDENT POLICY e AUGUST 8, 1985 e PRESENT REACTORS ARE SAFE EN0 UGH, BUT. . .
| |
| e SEARCH FOR OUTLIERS e CONSIDER EALANCE OF PREVENTION AND MITIGATION SPECIAL CONSIDERATION OF CONTAINT!ENT PERFORf".ANCE O
| |
| f e
| |
| O
| |
| | |
| : 2
| |
| ($) .
| |
| THE SEARCH FOR 00TLIERS e SEARCH FOR SIGNIFICANT VULNERABILITY FIND OUTLIERS NOT NECESSARILY GUANTIFY INLIERS e INDIVIDUAL PLANT EXAMINATION UNLESS ALREADY DONE IDENTIFY OUTLIERS BACKFIT AS APPROPRIATE O
| |
| e WHERE TECHNICAL ISSUE G0ES BEYOND CURRENT REGULATORY REQUIREMENTS GENERIC RULEMAKING PREFERRED
| |
| - ALSO USE BULLETINS, ORDERS OR GENERIC LETTERS 1
| |
| | |
| '' 3 GDC 16:
| |
| CRITERION 16 - CONTAINMENT DESIGN. --AN ESSENTIALLY LEAK-TIGHT BARRIER AGAINST THE UNCONTROLLED RELEASE OF RADI0 ACTIVITY TO THE ENVIRONMEi4T AND TO ASSURE THAT THE CONTAliiiiENT DESIGN CONDITIONS IMPORTANT TO SAFETY ARE NOT EXCEEDED FOR AS LONG AS POSTULATED ACCIDENT CONDITIONS REQUIRE."
| |
| GDC 50:
| |
| O "
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| CRITERION 50 - CONTAINMENT DESIGN BASIS. --AS REQUIRED BY SECTI0ii 50.44, ENERGY FROM METAL-WATER AND OTHER CHEMICAL REACTIONS THAT MAY RESULT FROM DEGRADATION BUT NOT TOTAL FAILURE OF E!',ERGENCY CORE COOLING FUNCTIONING, (2) THE i
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| LIMITED EXPERIENCE AND EXPERIMEiiTAL DATA AVAILABLE FOR DEFINING l
| |
| - ACCIDENT PHENOMENA AND CONTAINMENT RESPONSES, AND (3) THE CONSERVATISM 0F THE CALCULATIONAL MODEL AND INPUT PARAMETERS."
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| O
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| 4 .,
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| O O O :
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| I
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| ,- . {, b 4 -
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| TABLE 1 - U.S. BWR PLMT-SPECIFIC PRA STUDIES i. 4b.'Iu O PROGRM REPORT CORE / REACTOR CORE-DAMAGE EVENTS EDIM, CONTAIIDENT PLMT MAK REPORT YEAR CONIAlleENT POWER (Inff) FPEQUENCY PRA CONSIDERED MEM OR CONDITIONAL ESTIMATE POINT FAILURE ESTIMATE P908 ABILITY 3x10
| |
| -5 Internal / Median Met evaluated Peach RSS WASH-1400 1975 BWR-4/MK I 3293 Sotton External i
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| 4x10
| |
| -5 Internal Mean 0.2 l Peach 10COR Tech Summary 1984 OWR-4/let 1 3293 '
| |
| : Botton Task 21 -5
| |
| ! Peach IPE IPE 1986 OWR-4/let ! 3293 2x10 Internal Mean Not evaluated l Bottaa 3x10
| |
| -4 Internal Median Not evaluated Millstone IREP NUREC/CR 1983 BWR-3/MK I 1727 3085 4 Millstone NUSCO Millstone 1 1986 BWR-3/let I 1727 5x10 Internal Mean Not evaluated j PSS
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| ~4 Broun. Ferry IREP NUREG/CR 1982 BWR-4/let I 3293 2x10 Internal Point Not evaluated i 2801 Estlante
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| ~
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| 3x10
| |
| -5 Internal Mean 0.07 Vermont VYCSS VYCSS 1986 BWR-4/let I 1593 .
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| Yankee .
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| ) Big Rock Consumers Big Rock 1981 BWR-1/ Dry 158 1x10'3 Internal / Mean 0.25 Point Point PRA -3 External l Bla Rock EG8G/9NL EG&G-EA- 1982 BWR-1/ Dry 158 1x10 Internal / Mean 0.25 1 Point 5533 Rev. 1 External
| |
| -5 Internal / 1.0 Lleerick PEPC0 Limerick PRA 1981 BWR-4/MK II 3293 7x10 Mean External 1x10
| |
| -4 Internal / Mean 1.0 l Limerick SNL NUREC/CR- 1983 BWR-4MetII 3293
| |
| ' 3028 External Shoreham LILCO Shoreham PRA 1983 BWR-4/let II 2436 5x10-5 g,g,,,,3 ,,,,g ,,g ,,,y ,,g,,
| |
| Estlante Shoreham BNL NUREG/CR- 1985 BWR-4/IEL II 2436 1x10-4 Internal Point Met evaluated 4050 Estlante Shoreham IPE Shoreham IPE 1986 BWR-4/let 11 2436 8x10-5 Internal Mean Not evaluated 5::- - ': BWR-4/let II 2x10'I Internal IPE IPE 1986 3293 Mean Notevaluateg Grand Gulf BWR-6/letIII 3833 -5 R$$ MAP NUREG/CR- 1981 4x10 Internal Median Not evaluated 1659 Grand Gulf Tech Simmary 1984 BWR-6/Ist III 3833 -6 10COR 8x10 Internal Mean Not evaluated Task 21
| |
| ) GESSAR GE GESSAR 11 PRA BWR-6/IEL III 3579 4x10'4 Internal / Maan Not evaluated j External CD 4
| |
| | |
| -- i 7
| |
| ~
| |
| * gp _
| |
| KEY RESULTS FOR BWR CONTAINMENTS e REACTOR SAFETY STUDY - PEACH BOTTOM 90% EARLY RELEASE e IDCOR PEACH BOTTOM 20% EARLY RELEASE o VERM0i1T YANKEE - 7% EARLY RELEASE O
| |
| e NUREG-1150 i
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| e
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| _g o
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| 8' l -
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| m O .
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| ~M. kN!
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| s 5
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| 1 ~~
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| h
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| *;. 3
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| . Tllid. ..:
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| 1 h }, 5' q. ,i 4 {
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| * 'l
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| *. k
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| PA*Amy sysTEu 'i o g" /._ c & ::t j ORYWELL -
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| 'i::-
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| ~'
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| i
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| , $?bf5b;&$, '
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| u-
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| . {h
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| ~
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| h*
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| -. 4' '
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| $ PEDESTAL CAVITY WM
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| ~
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| J 2 lg ~Q. j
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| ~
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| 3
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| {
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| :n N % l
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| ,$..ht.u,rn:, i,1M %,,,..>.,,"- 'T
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| 's
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| ,.$.,>9 ,
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| ~
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| a 5
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| 's ,. 4* /
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| )
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| TYPICAL MARK I CONTAINMENT DESIGN: !
| |
| FIGURE 1 i O 4 a
| |
| N o ~2
| |
| | |
| 3 10 O BWR CONTAINMENT ISSUES - I1 ARK I ,
| |
| e SMALL VOLUME MORE RAPID OVERPRESSURE ESPECIALLY VULNERABLE TO HYDROGEN BURN e SMALL DRYWELL FLOOR LOWER HEAD AREA.CLOSE TO DRYk! ELL WALL POTENTIAL FOR DIRECT DEBRIS ATTACK DIRECT RADIATION AND CONVECTION HEATING O
| |
| e LIMITED PASSIVE CAPABILITY BUT OPTIONS FOR ACTIVE RESPONSE e 5-ELEMENT APPROACH HYDROGEN CONTROL SPRAY IN DRYWELL PRESSURE RELIEF DEBRIS CONTROL PROCEDURES AND TRAINING O
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| J
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| , - - - - - . - - - - . ,--._-.-......---..-.,,_.--_-n,,,__,,-__--_._,,.n.- ,,, - - - ,. -- - - , . -- . - - - - - - - -,, - , - ,._,,., - - , , -- . ,,, . _ _ . n , - ,.
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| | |
| ; ~, 11
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| ($) .
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| CONTAINMENT IMPROVEMENT STRATEGY e PREVENT HYDROGEN COMBUSTION BY INERTING e REDUCE DRYWELL SPRAY FLOW RATE PERMITS ALTERNATE SUPPLIES TO PRODUCE SPRAY EXTENDS WATER SUPPLIES e PROVIDE RELIABLE BACKUP SUPPLIES FOR DRYWELL SPRAY PROVIDES SHALLOW POOL OF WATER ON DRYWELL FLOOR DIRECT SPRAY COOLING 0F ANY CORE DEBRIS LEAVING LOWER
| |
| () HEAD AREA i
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| SPRAY SCRUBBING OF DRYWELL VOLUME DIRECT COOLING 0F WALLS e WETWELL PRESSURE RELIEF TO STACK POOL SCRUBBING ELEVATED RELEASE e DEBRIS CONFINEMEllT e TRAINED OPERATORS
| |
| , ()
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| -.- -~ --.,--,,- - __-
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| | |
| WJ[
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| r so y _ c- s mn e c m lIs rim a m a m :: we = -e;;j 91 i nsn ,: Mi M M i i MM ! b E
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| = ~_
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| 7g ~'
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| #e.= ==
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| - ='j j =i r52 -1= r =_ T.i.E . ==== = =====
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| 53='- - - - -
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| ===m =~
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| ':=
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| 31
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| = =
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| Ri= l=~-f
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| =
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| -- P T H, ! FIGURE,,_2__,_ Mi
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| " ~
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| * ~
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| *; i *i *i .1 i + i E G 4 6:@
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| EXPECTED WHOLE B00Y RADIATION DQSE (REM).
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| 4i ?
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| % -=
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| ;s33 is9 ~
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| --Z
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| ~
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| FROM RELEASE OF 100% NOBLE GASES e=
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| : : ; ; C g ; = 5:: aee aer -
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| (I HOUR DECAYED AND 5 HOURS DURATION -- - OF= = = == == =
| |
| a___ RELEASE) FROM 3412 MWt LWR VS. DISTANCE S
| |
| NOTES:
| |
| l' Graphs assume one hour holdup and decay prior to release. Greater delay in release can produce 10M. G i i sM Ms! lower doses (e.g., as much as a factor of about 10 el M E == ==: 30 at one mile for 12 hours of inreactor holdup u : : : : :: = =
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| j i
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| a E29 r--- --- comparedtoonehour). - ;
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| p _ _ _
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| ~
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| ~~
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| g ====
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| d ed
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| =;
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| e* ; -
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| m m 2., Dose estimates are based upon MCCS computer 13 : = :a
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| - iiE code calculattons using revised (relative to , _
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| : : - : w2s El 'l,EE5M ,==
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| M 22 2 ==
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| CRAC and CRAC2) meteorological sampling models.
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| i :: M .
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| =~ - - - - - ~
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| &o =
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| EEE E 3. The likelihood of exceeding the -
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| 3 a .-
| |
| estimated 95 percentile dose is less
| |
| * tj than 55 given release of 100% of -:
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| l ;
| |
| " ' noble gases as'specified above. :EE:5' l
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| M 5:
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| .g- +--,, , ..
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| w Sa Mi k teg b!f) i D Y $ !-h k)~Ni , ESTIMATED g: {0(
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| lg ,s *[! a ==r t
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| , e4: isi =====
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| n
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| ~ -
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| , GROUND VEL pE5 b10 METERS -
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| ik -
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| 2 :
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| 'g .
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| _5
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| ; m; lu;E *W H F
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| tit id H- C a m=
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| H iF H N! U dd = s a = -
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| ESTIMATED 95 PERCENTILE if $g i
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| M Es is EE
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| ==
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| bj[M @ ip =s: := 5m3= =====
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| i E
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| ==
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| y;; ; ;;= g=i 2
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| ELEVATED _R_ELEASE 100 METERS n_. :
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| 2-g 3 g 1_ -'= _ _
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| s, M
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| w g
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| -. yj:
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| $9 M "'''' (s \s b w:
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| ,y Mgeti: ii i h:m%M s -
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| r
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| * m .i m m sW PN"- s: :
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| M M f "-
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| -= ~
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| .c l_2
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| = =
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| ._=_ __=
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| =.. ==
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| ===
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| 2.= = siQb
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| - % c --
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| i GROUND LEVEL RELEASE 10 METERS O'
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| ~ ~ M
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| '~
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| sQ: :, :.__y g .
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| -W
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| ., , A
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| = m :
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| ; 7,g y ; m. ; ei g m: m s ~u W
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| i !J %
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| -m i k 4-5 [h ; Mi .'-s! 5 5 5S 55 s
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| I i3 5 [, d
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| _ . e dd 5 [=3 7 35 !!i 33 5- blu d5l .31 j 2! !kh 23' i i i '
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| : ha i 55 E=1: 5 E ii : 5.i 55 - !E* [3_
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| jj ' jjj M Z -i[ii
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| ]
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| ~
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| 511 iii. !%
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| { .'f.~ f5 !ff : : Z IE =
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| I i '!!! Us E=:: = EE = : =
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| 45f 53 I W m( j$ :=- +--
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| 336lE5 57
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| 'a j -
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| S -
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| : u. -_
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| , g; g ggi O- ELEVATED RELEASE 100 METERS # -%- -
| |
| ig__ __ ,__
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| 8 w.
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| p +_ __+ - - .-- - _ -- .- -
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| ::: ;-: ::: :: ::: =: ::: :::s s 1 -
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| wEE E_E____
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| E: :::_q::p::::i:::::i;@:: ::: ::: :: :::
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| I:::: :: ::::: ::: :: ::: : : :e jij;/3!
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| : -- - '8' E a m_g DISTANCE FROM RELEASE POIKT (MILES) -_ = 4 i iii i i i ii i i i iii i i i iii i i i ii i i i ii i i i J
| |
| ( 3, a3 4, 5 ~6 'I ~ 8 9 0 11 12, 15
| |
| 'i M
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| t '
| |
| 16 1 _
| |
| ~
| |
| CONDITIONS QUALITY AND DESIGN STANDARDS SINCE THESE REGUIREMENTS ARE INTENDED TO BE AN OPTIMIZED USE OF EXISTING EQUIPMENT IT IS EXPECTED THAT ADDED EQUIPMENT, OF ITSELF, NEED NOT MEET THE QUALITY OR DESIGN STANDARDS OF SAFETY RELATED EQUIPMENT, NEVERTHELESS, MODIFICATIONS TO OR NEAR EQUIPMENT OR SYSTEMS WHICH ARE ALREADY SAFETY RELATED SHALL NOT COMPROMISE THE QUALITY OF SUCH EQUIPMENT OR SYSTEMS.
| |
| O IMPLEMENTA M THE EQUIPhENT CHANGES REQUIRED HEREIN SHALL BE INSTALLED DURING THE FIRST REFUELING OUTAGE WHICH LEGINS NINE (9) MONTHS AFTER THE EFFECTIVE DATE OF THIS LETTER. THE PROCEDURE 0 AND TRAINING REQUIRED SHALL BE IMPLEMENTED ON A SCHEDULE REVIEWED AND APPROVED 4
| |
| BY THE NRC. GIVEN THE IllPLEMENTATION OF THE GENERIC IMPROVEMENTS OF MARK I CONTAINMENTS THERE IS NO NEED FOR AN INDIVIDUAL PLANT EVALUATION (IPE) FOR CONTAINMENT PERFORRANCE. THIS DOES NOT REMOVE THE NEED FOR AN IPE WHICH COVERS THE SYSTEM RELIABILITY OR CORE MELT FREQUENCY PORTION OF THE SEVERE ACCIDENT QUESTION, O
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| | |
| p . . _ _ _ . . _
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| 17
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| ~
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| .... .. .. t SEVERE ACCIDENT POLICY STATEf;ENT l e OPERATING NUCLEAR POWER PLANTS REQUIRE NO FURTHER REQULATORY~
| |
| ACTION TO DEAL WITH SEVERE ACCIDENT ISSUES UNLESS SIGNIFICANT NEW SAFETY INFORMATION ARISES T0 QUESTION WHETHER THERE IS ADEQUATE ASSURANCE OF NO UNDUE RISK TO PUBLIC HEALTH AND SAFETY, e IN THE LATTER EVENT, A CAREFUL ASSESSMENT SHALL BE MADE OF THE SEVERE ACCIDENT VULNERABILITY POSED BY THE ISSUE AND WHETHER THIS VULNERABILITY IS PLANT OR SITE SPECIFIC OR OF GENERIC
| |
| ! IMPORTANCE.
| |
| 4
| |
| ($)
| |
| e THE MOST COST-EFFECTIVE OPTIONS FOR REDUCING THIS VULNERABILITY SHALL BE IDENTIFIED AND A DECISION SHALL BE REACHED CONSISTENT
| |
| : WITH THE COST-EFFECTIVENESS CRITERIA 0F THE COMMISSION'S BACKFIT POLICY AS TO WHICH OPTION OR SET OF OPTIONS (IF ANY)
| |
| ARE JUSTIFIABLE AND REQUIRED TO BE IMPLEMENTED.
| |
| 4
| |
| .e IN THOSE INSTANCES WHERE THE TECHNICAL ISSUE G0ES BEYOND CURRENT j REGULATORY REQUIREMENTS, GENERIC RULEMAKING WILL BE THE PREFERRED SOLUTION. IN OTHER CASES, THE ISSUE SHOULD BE DISPOSED OF THROUGH THE CONVENTIONAL PRACTICE OF ISSUING BULLETINS AND ORDERS OR GENERIC LETTERS WHERE MODIFICATIONS ARE JUSTIFIED
| |
| () THROUGH BACKFIT POLICY, OR THROUGH PLANT-SPECIFIC DECISION-NAKING ALONG THE LINES OF THE INTEGRATED SAFETY ASSESSMENT PROGRAM (ISAP) CONCEPTION.
| |
| I
| |
| | |
| 1
| |
| . , 16
| |
| ~
| |
| 0 .
| |
| C0ffilSSION RESPONSE TO A HEARING QUESTION JULY 16, 1986 QUESTION IS A 90 PERCENT CHANCE OF FAILURE IN THE EVENT OF A CORE MELTDOWil All ACCEPTABLE FAILURE RATE?
| |
| ANSWER THE NRC HOLDS THE POSITI0ll THAT THE LIKELIHOOD OF CORE fiELT ACCIDENTS IN AliY PLANT SHOULD BE VERY LOW AND, IN ADDITION, O THAT THERE SHOULD BE SUBSTANTIAL ASSURANCE THAT THE CONTAINMENT WILL MITIGATE THE CONSEQUENCES OF A CORE MELT SHOULD ONE OCCUR IN ORDER TO ENSURE LOW RISK TO THE PUBLIC. IT IS NOT MERELY A QUESTION OF HAVING LOW RISK BUT OF HAVING AS WELL THE DEFENSE-IN-DEPTH ASSURANCE OF C0!1BINED PROTECTION BY PREVENTION AND tilTIGATION...
| |
| i
| |
| !O
| |
| | |
| i
| |
| [._ 18A
| |
| ~
| |
| 'O .
| |
| TABLE 3 COST-BENEFIT ANALYSIS COST: $0.7-2.2M BENEFIT:(1) FCM CCFP CCFP AVERTED AVERTED BEFORE AFTER LOSS /YR LOSS PRES. VALUE BASE
| |
| ~4 CALCULATION 1x10 /yr 0.5 0.05 $4x105 /yr $3M/$12M
| |
| -5 LOWER FCM 1x10 /yr 0.5 0.05 $4x104 /yr $0.3M/$1.2M O LESS CHANGE
| |
| -4 IN CONTAINMENT 1x10 /yr 0.5 0.1 $4x105 /yr $3M/$12M BETTER CONTAINMENT
| |
| -4 l
| |
| TO START 1x10 0.2 0.05 $2x105 /yr $2M/$6M 0PTIMISTIC"
| |
| -5 CALCULATION 1x10 0.2 0.05 $2x104 /yr $0.2M/$0.6M
| |
| " PESSIMISTIC"
| |
| -4 CALCULATION 3x10 0.9 0.1 $2x105 /yr $16M/$60M O (1) FCM = Frequency of Core Melt CCFP = Conditional Containment Failure Probability AVERTED LOSS PRESENT VALUE expressed as A/B where A is the averted loss per year times 8 (roughly equivalent to discount at 125/yr rate) and B is ,
| |
| the averted loss per year times 30 (no discount). -
| |
| | |
| 19 Pi<0P6 SED CTI N e DEC. 9 a 12, 1986 ACRS REVIEW e DEC. 19, 1986 CRGR REVIEW e JANUARY 1987 REVIEW 0F ACRS AND CRGR REACTION WITH COMtilSSION e FEB.1,1987, PUBLISH PROPOSED GENERIC LETTER FOR C0ffiENT O . MAY 1987 ISSUE FINAL GENERIC LETTER SIMILAR LETTERS ON MARK II AND MARK III TO FOLLOW O 0
| |
| | |
| BWR OWNERS' GROUP O SEVERE ACCIDENT CONTAINMENT ISSUES NUMARC APPROVED SEVERE ACCIDENT CONTAINMENT ISSUES APPROACH
| |
| : 1. OBJECTIVE EVALUATE CONTAINMENT INTEGRITY. IF APPROPRIATE, ASSESS POTENTIAL IMPROVEMENTS TO MINIMIZE OFFSITE RELEASES FOR SEVERE ACCIDENT CONDITIONS (BEYOND DBA) WITHIN AN APPROPRIATE COST / BENEFIT GOAL.
| |
| . 2. IDENTIFY CHALLENGES TO CONTAINMENT
| |
| * 1.)
| |
| H2 GENERATION
| |
| : 2) OVERPRESSURE 3.) TEMPERATURE 4.) CORE DEBRIS ATTACK 5.) FISSION PRODUCT CONTROL g 6.) HUMAN ACTIONS M . DIRECT CONTAINMENT HEATING
| |
| : 3. IDENTIFY INITIATORS TO EACH CHALLENGE FROM EXISTING ANALYSES i PICK KEY EVENTS / INITIATORS (MOST SEVERE - LESS SEVERE)
| |
| SEQUENCE THAT PRODUCES MOST SEVERE CHALLENGE
| |
| : 4. ASSESS PLANTS' ABILITIES TO MEET CHALLENGES
| |
| : 5. ASSESS PLANT VULNERABILITIES
| |
| : 6. PROPOSE ALTERNATIVES TO ADDRESS VULNERABILITIES
| |
| ! 7. EVALUATE ALTERNATIVES
| |
| : 8. REACH DECISIONS l0
| |
| * OTHER ISSUES TO BE ADDED OG37/12.12 1
| |
| ..,--,..,.,.---,_,_m-...-,,v_,__.._,-}}
| |