ML19329G167
| ML19329G167 | |
| Person / Time | |
|---|---|
| Issue date: | 06/26/1980 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| Shared Package | |
| ML19329G168 | List: |
| References | |
| REF-10CFR9.7 NUDOCS 8007140065 | |
| Download: ML19329G167 (58) | |
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7 DIS M A W n 7
This is an unofficial transcript of a maating of da United States Nuclear Regulatory Con: mission held on June 26, 1980
,. in the Commission's officas at 1717 E Stranc, N.
W., Washington, D. C.
The maating was open to public attendanca and observacion.
. This transcript has sat baan :nviewed, corrac:ad, or adicad, and
.it may contain inaccuracias.
t The transc=1pt is incandad solely for ganaral info:=a:1onal purposes.
As provided by 10 CF3. 9.103, it is not part of da fo= mal or info: mal :scord of decision of the =a::ars discussad.
Expressions of ophdon in dis transcript de not cacassarily raflace final data h tions or saliafs.
No pleading or ochar paper nay be filed with the Commission in any procandi=g as ha resuir of or addressed to any scaramant or arg'.=ta=c contained harmin, except as che Commission nay authoriza.
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UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION 3
DISCUSSION OF SECY-80-107 - PROPOSED INTERIM HYDROGEN 4
CONTROL REQUIREMENTS FOR SMALL CONTAINMENTS 5
PUBLIC MEETING 6
7 Nuclear Regulatory Commic; ion Room 1130 8
1717 H Street, N.
W.
Washington, D.C.
9 Thursday, June 26, 1980 10 The Commission met, pursuant to notic<s, at 11 3:30 p.m.
12 BEFORE:
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JOHN F.
AHEARNE, Chairman of the Commission 1-4 VICTOR GILINSKY, Commissioner RICHARD T. KENNEDY, Commissioner 15 JOSEPH M. HENDRIE, Commissioner PETER A.
BRADFORD, Commissioner 16 ALSO PRESENTS 17 L. BICKWIT W.
DIROKS 18 H. DENTON D. ROSS 19 L. RUBENSTEIN W.
BUTLER 20 R. BERNERO M. MALSCH 21 '
- 3. BUCHHOLZ J. STARK 22 23 Pages 1 to 56
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CHAIRMAN AHEARNE:
The Commissioner meeting this 3 afternoon follows from a req.est originally put out by 4 Commissioner Gilinsky in whicP he asked that we have another 5 meeting on the proposed interim hydrogen control 6 requirements for small containments.
It was a SECY paper 7 80-107.
8 In his call for the meeting Commissioner Gilinsky 9 expressed a particular concern with the ice condenser 10 plan ts, especially the D. C. Cook units and Sequoyah.
He 11 has. recently returned from an on "tte visit at Sequoyah.
12 We have an additional Commission paper on the 13 particular subject at hand, SECY-80-107B of June 20, to add 14 to the large amount and large collection of information we 15 have.
16 We have an august array of individuals on the 17 other side of the table.
'), Bill, as the senior staff 18 member on that side let me ask you what you have.in mind.
19 ER. DIRCKS For the briefing that you have 20 described that Earold and Dennie will certainly bear the 21 burden of I have also asked Bob Budnitz and Tom Merley to be 22 available to talk about the scope, direction and pace of the 23 studies and research program that is involved, particularly
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24 including whatever short-term studies that are going on 25 relating to the ice condenser situation.
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MR. DENTON:
Since we have talked to you last, we 2 have continued a program of evaluating the. efficacy of 3 various hydrogen control "easures.
Today we want to 4 describe the bases for our response to you a few days ago 5 answering Commissioner Gilinsky's last few questions.
6 Dennie Ross will make the presentation.
7 (First slide.)
8 MR. ROSS:
As we go through the briefing this 9 af ternoon the people here at the table who might respond to 10 your questions are to my immediate lef t Less Rubenstein, 11 Assistant Director for Core and Containment Systems, and to 12 his lef t Walt Butler, Branch Chief of the Containment 13 Systems Branch.
If we get into any structaral matters Fron 14 Showers of the Structural Engineering Br'nch is here.
On a 15 related matter of the proposed interim rule under graded 16 cores Jim Norberg from the Office of Standard Development is e
17 in the audience if we have any questions on that related 18 matter.
19 Go to slide two.
20 (Next slide.)
21 Mitters that we are prepared to discuss this 22 af ternoon, I will get into the chronology and discuss the 23 issues.
I might point out that the issues on hydrogen 24 control will be brought to the Commission for more formal Zidecisions in two separate arenas.
The issue of Sequoyah b
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4 1 full power will come to the Commission shortly and hydrogen 2 management we expect to be discussed there.
Also when the 3 interim rule is brought up for to the Commission for 4 endorsement you will be discussing and either commenting or 5 concurring on a proposed hydrogen management policy.
We are 6 not requesting any formal Commission decisions or guidance 7 this afternoon.
8 CHAIRMAN AHEARNEa Although you may get it.
9 COMMISSIONER HENDRIE:
I was going to say, 10 decisions I doubt you will get but guidance I would be 11 surprised if you can avoid.
12 (Laughter.)
13 MR. ROSS:
Nolo content ere on that.
14 (Laughter.)
15 CHAIBMAN AHEARNEt It is creeping everywhere.
16 (Laughter.)
17 MR. ROSS:
We will discuss the decision elements 18 on how to decide whether additional hydrogen management 19 measures are needed in a given containment.
These include 20 the likelihood of events, the response to the containment 21 both in whether you are going to expose a burnable mixture 22 c: not and a structural response and the availability and 23 practicality of various mitigation measures.
24 There is a relatively small but growing research 25 program on various areas of hydrogen mitigation.
We will
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1 discuss those.
The related topics I mentioned briefly 2 already, the rulemaking ventures and the Zion / Indian Point 3 plant specific natter which has hydrogen control measures 4 th e re.
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5 Go to the next slide.
6 (Next slide.)
7 As Harold mentioned, the base document is 8 SECY-SO-107 which came to the Commission in February.
We 9 had a briefing in March and supplemental questions in late 10 March and then we have provided answers to the Commission 's 11 questions in April as SECY-107A and then again last week
,e believe that we have completed the response 12 with 107-B.
W 13 now to the Commission's questions of March.
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14 Next slide, please.
15 (Next slide.)
16 Unless there is a specific request, I was not l'7 going to go back and summarize the contents of either 107 or 18 107 A.
The thrust of the document that you just got last 19 week, 107-B, we had been asked to provide the views of the 20 probabilistic assessment staff.
We provided as an enclosure 21 to the paper an integral report from the previous speaker, 22 Br. Bernero.
By the way, I believe Mr. Bernero is still in 23 the audience, and along with Mat Taylor, who contributed to 24 the document.
25 Inerting would have a small value in the overall i
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1 accident risk reduction for the MARK I and MARK II 2 containments.
Some of the features that lead to that 3 conclusion is the f act that you can get containment failure 4 before the onset of metal water reaction for some sequences 5 due to steam overpressure.
6 We also pointed out in our view, that is, in the 7 view of the originating office, NRR, that the PWR/BWR 8 designs were we thought in the same order of magnitude in 9 terms of likelihood of having a degraded core per year.
10 Some of the numbers you saw in the earlier paper from Mr.
11 Bernero I think by and large agreed with that.
12 We felt in terms of the lessons learned from Three 13 Mile Island, and this is in response to a specific g
14 Commission request, that, yes, some credit could be given to 15 lessons learned, that is, the large body of improvements on
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16 operating reactors in the last 15 months should, in our 17 opinion, reduce the likelihood of a severe or a degraded 18 core per reactor year.
19 As a supplement to our 107B paper we provided an 20 analysis from the Division of Safety Technology of NRR that 21 did not appear to be a significant reduction in safety by 22 inerting the BWR MARK I and MARK II, and this would agree 23 within the views of the PAS.
24 COMMISIONER KENNEDY:
You said there would not be 25 a significant reduction?
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1 MR. ROSS:
Significant reduction.
2 CONNISSIONER KENNEDY:
That means there would be 3 some?
4 MR. ROSS:
Tnere is a tradeoff, and numerically I 5 don't believe we could provide an answer.
There is a 6 day-to-day advantage in having a non-inerted containment.
7 You would probably be more likely to go in and do an 8 inspection.
To that extent inerting would be a 9 dinincentive.
On the other hand, there are some sequences 10 for which you woul?. not get containment failure if you 11 inerted and that would be an advantage.
12 In our view, risk assessment will not permit one 13 to decide one way or the other because it is sort of too 14 close to call.
That is the flavor I got from the PAS paper 15 also, t (though you may ask them directly.
16 COMMISSIONER KENNEDY I wanted to be sure I 17 understood what you just said that on the risk assessment 18 basis when you add the negative and positive you come out to 19 assentially zeros is that right?
20 MR. ROSS:
Well, it is within the margin.
- Yes, 21 sir, zero interpreted as being the margin of the spread of 22 risk assessment.
Like I said, the originating office's 23 viewpoint, Mr. Bernero may want to put it a different way.
24 CHAIRMAN AHSARNE:
Do you, Bob?
Do you want to 25 put it a different way?
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1 MR. BERNERO:
Dennie has to make a risk 2 assessment.
We evaluated the effect of inerting on the 3 accident sequences, but did not evaluate the counterpart of 4 it, you know, the maintenance and accer,sibility and so 5 forth.
So ours was a more narrow scope.
6 CHAIRMAN AHEARNE In your more narrow scope the 7 conclusion you reached ---
8 HR. BERNERO:
---said that the benefit of inerting 9 appeared to be marginal.
10 COMMISSIONER KENNEDY:
That is even without 11 considering maintenance?
12 MR. BERNEB04 Without considering the maintenance.
13 COMMISSIONER KENNEDY Well, I guess that does 14 come out about the var Dennie is saying.
Okay.
15 MR. ROSSa In our paper, 107B, we continued, 16 howeven, to support the viewpoint that you should inert the 2
17 MARK I's. and MARK II's.
The logic that we prcvided was 18 threefold that it is a proven technology; apparent low 19 co st', low being relative of course; and that we did not see 20 any significant safety disincentives.
21 COMMISSIONER KENNEDYa Would you remind us what 22 that low relative cost vas?
23 MR. ROSS:
I believe it is one or two million
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24 dollars per year.
25 We did provide by Commission request two i
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Q 1 additional letters from General Electric giving their 2 viewpoints, and those are enclosed to the Commission paper.
3 Our view of those letters is that the GE believes they have 4 a superior design which would reduce the likelihood, and 5 they believe that the preferred way to solve this problem is 6 through the rulemaking procedure.
7 ER. DENTON:
I do want to say just a bit about the 8 use of risk assessment for a spe'cific area like this.
It is 9 sort of a microrisk assessment as opposed to a big risk 10 assessasnt.
Whether or not a p' articular corrective action 11 helps a lot depends on what you think the dominant sequences 12 are.
If you think some other sequences dominate the risk 13 then something you put in to help a specific one has little 14 credit, whereas if that one you have corrected for is the 15 one that really happens, as the one at TMI was the case for 16 their extensive core damage but no containment l'7 pressurization, then it would have made a substantial 18 differen:e, or could have made a substantial difference.
19 COEMISSIONER GILINSKI I wonder what the response 20 of the probability assessment people to that.is?
I guess I 21 am not sure I understand your point of view.
Is it that you 22 feel there would be f ailure through overpressurization 23 coming from sources other than hydrogen that would proceed 24 possible problems with hydrogen and theref ore there is no 25 point in, so to speak, def ending against that, or what, j
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J 1 because at TMI ve did in f act rur into a r,ituation where the 2 hydrogen was in fact being the dominate source of high 3 pressure.
4 MR. ROSS:
Who were you addressing that to, Bob 5 Bern ero ?
6 MB. BERNERO:
I wasn't sure whether Harold wanted 7 to some something else.
Really what the risk assessment 8 such as we are doing does, it says on average, statistically 9 or probabilistically looking at' the spectrum this is how it 10 balances out.
What I understood Harold to say was that that il still leaves a family of sequences which may not indeed be 12 the odds on favorites.
They may not necessarily be th e 13 dominant ones, but they are there and there is a way to deal 14 with them.
That is what I interpreted him to say, I am not 15 sure, and I agree with that, yes, the risk can be reduced.
16 All we are saying with a probabilistic comparison such as 17 was done for the inerting of the MARK I there was that the 18 degree of overall risk reduction is modest or marginal or 19 small, whatever word you would pref er on balance, but it 20 doesn ' t say that it is zero.
21 COHHISSIONER KENNEDY:
I didn't understand Dennie 22 to say that.
He, too, said that the benefit was there but 23 small, admitted, and that there were tradeoffs which also i
24' vere small, and I said, does that add to essentially zero, 2 and you know, plus or minus some fraction, and the answer is s
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2 COMMISSIONER GILINSKYa Well, it sounds to me as 3 if it is zero if you are confident that the sequences that 4 ve think are dominant are in fact dominant and that the 5 rel= ' i ve probabilities are about right.
If one has some 6 doubt about that one may want to hedge against the 7 possibility that there are other sequences which we may 8 underestinate.
9 MR. BERNERO:
That our cast of sequences may not 10 be accurate.
We are not that certain of it.
11 COMMISSIONER KENNEDY:
Is that true equally as to 12 the possible negative effects?
We are not that sure of that 13 either?
I guess that is true.
14 MR. ROSS:
This is one question we had been asked 15 as to the experience on entering the dry well because that i
16 is the area where we speak of disincentives.
We did provide 17 the information and it looks to us like there is little or 18 no t correlation between dry well entries between inerted and 19 noninerted.
It looks more like the correlation, and it is a 20 weak one at best, between a new plant and an old plant.
So 21 the younger BWRs inerted or not seem to get more unscheduled 22 dry well entries than the more mature plant.
23 CHAIRMAN AHEARNEa That wasn't surprising, was it?
24 MR. ROSSa I guess not.
I think the so-called 25 bathtub curve prevailed there as well.
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Okay, on the slide that you now see we have tried 2 to put up the issues associated.
This is sort of a decision 3 tree for us.-
It categorizes the plants in more or less 4 increasing containment volume.
We are asking questions like 5 shall the MARK I's be inerted that are operating, which 6 would affect only Vermont Yankee and Hatch because the 7 others are?
Should t,he new plants in the operating license 8 phase be inerted?
9 CHAIRMAN AHEARNE:
Those are plants that are 10 designed to be able to be inerted but are not currently 11 planned to be inerted?
12 MR. ROSS4 It is our understanding, and Walt can 13 maybe add on to it, that you could without much trouble 14 adding the inerting f eature.
15 NR. BUTLER:
That is true.
16 3R. ROSS:
Okay.
Now, the first of these plants 17 w o n ' t come on line for another year anyway it looks like'.
18 MR. DENTON:
I guess I am one who thinks that the 19 downside of a plant that is designed to be inerted is mainly 20 financial.
In other words, if you design it for inerting 21 then you can compensate for design and you don't have to 22 make the entrances.
However, it is a different picture if 23 you make that balance for a plan that is not designed for 24 in e. tin g.
Then there are more disadvantages when you inert.
25 CHAIRMAN AHEARNE But I and II have been designed k
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13 1 to be inerted; is that correct?
2 HR. DEN":
Yes.
3 MR. RC Point No. 3 is should additional 4 hydrogen aitigation measures be required for the ice 5 condenser?
This would affect two units in the full power 6 state, the Sequoyah anit in the start-up phase and then 7 seven other units in different construction phases.
8 CHAIEMAN AHEARNE:
D. C. Cook are the ones
'at 9 are in the operating phase?
10 MR. ROSSs D. C. Cook I and II are the only two in 11 the full power mode and then of course Sequoyah I in the 12 start-up mode followe'd by the other Sequoyah plant, 5cquire, 13 Watts Bar and Catawba, two units each, and of course if the 1-4 off shore power builds, those also.
15 The first MARK III is Grand Gulf and it would come 16 into operation late 1981.
The question there is do we need i
17 more for it?
Then finally, do we need more for the large 18 dry containments in the subatmosphere.
Those seem to us 19 like dividing up the issues into something we can chew on.
20 Next slide.
21 (Next slide.)
22 It seems like there are four decision elements.
23 The front end or the probability that the event would occur 24 in the first place, and this is onc area where we answered 25 the Commissf or saying we think there has been a net ALDERSON REPORTING COMPANY, INC.
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I reduction already over the last 15 months as a result of TMI 2 lessons learned.
3 The second decision element would be related to 4 the rate at which hydrogen would build up in the containment 5 per unit time or per unit ZR-water reaction.
6 The third decision element would be how well the 7 structure could respond to various amounts of hydrogen 8 combustion.
9 The four decision element was how readily 10 available and effective would be various mitigation devices 11 like combusion suppression through hylon or inerting and 12 perhaps early burning, and in the extreme some late event 13 that the cressure is a result of burning.
14 Let's have the next slide.
15 (Next slide.)
16 This is put in for reference purposes.
Since the l'7 Commission issued it I won't dwell on it.
It is the recent 18 policy on CLI-80-16 on hydrogen management.
The relevance 19 has to do with on a plant to be licensed.
Can we permit 20 additional hydrogen measures as contrasted with can we 21 require hydrogen measures.
22 We read the Commission decision as saying that 23 additional measures could be required for hydrogen control 24 if there was a credible LOCA scenario.
We ptt that in there 25 in terms of the regulations permittinc us to require things.
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1 COMMISSIONER GILINSKY:
Could you repeat that' 2
MR. DENTON Let me try to say it a different 3 way.
I read this as issuing guidance f or :ase-by-case 4 adjudication of this issue.
It wasn't available when wc 5 first formulated our papers to you, but now it does set 6 policy for future adjudication in these areas.
7 COMMISSIONER GILINSKYa This is the TMI state {
8 MR. ROSSs This is the TMI policy statement 10 9 response to this certified question f rom the Board.
10 CHAIRMAN AHEARNEs Yes, it was an order that i
11 wa s ---
12 COMMISSIONER GILINSKY s I know what we are tal 13 about now.
14 MR. BICKWITa Then that tracks with your readi 15 That is fair.
16 COMMISSIONER GILINSKY Let's see now, you feq l'7 you can only require hydrogen mitigation measures if thh 18 is a specific scenario that you can march through that 19 take you to a place where you feel you would need them? l 20 MR. ROSSs Well, not quite.
50.44 lets us 21 require, for example, recombiners now, but recombiners q 22 not do anywhere near what one would need to do for a 23 degraded core type hydrogen, a TMI type hydrogen releasq 24 COMMISSIONER GILINSKY:
Right.
25 MR. ROSS The question is what regulation wod 1
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,..l 1 permit us to require measures to combat TMI type hp 2 release, and the answer, I think provided through %
3 counsel's office was if we saw a credible LOCA sees 4 under part 100 we could require measures.
5 Now, the rulemaking that will be on the @
6 table next month, in my opinion, would supplant tha 7 for now we see this as authority.
Now, in all like 8 what we would do if we saw a credible LOCA scenario 9 fix the scenario.
Nonetheless, that mechanism exis 10 CHAIRMAN AHEARNE:
Pardon me?
11 MR. 2055:
Like the interfacing LOCA, if )
12 like it was a big problem you would fix the interf ac 13 and not put in hydrogen control.
14 CHAIRMAN AHEARNE:
I see.
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15 COMMISSIONERHE.iDRIE:
Or maybe do both,0 16 least fix the interfacing LOCA.
17 MR. ROSSs Right, as a minimum, yes.
18 Okay, next slide.
19 (Fext slide.)
20 COMMISSIONER GILINSKY:
Excuse me.
The C@
21 is in the position of saying that you cannot oppose 22 to deal with hydrogen in excess of five percent mets 23 reaction unless you can detail a specific series of 24 leading toward a problem situation.
25 MR. DENTON:
Under part 100.
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MR. ROSS:
That is my understanding.
2 C05NISSIONER GILINSKY Which leaves us in the 3 position of saying -- well, it is rather odd.
Here we are 4 and we have experienced Three Mile Island and there was a 5 lot more hydrogen generated there.
It leaves us saying that 6 the lesson of those events is if specific things happened 7,then we vill have to deal with them rather than if certain 8 unexpected events happened.
9 CHAIRMAN AHEARNE:
Those are the same points that 10 you made at the time that the Commission affirmed the 11 order.
As we pointed out at the same time we do have this 12 rule on degraded core coming up.
So, yes, those were the 13 relevant points you made at the time.
1-4 MR. HENDRIE:
And I would like to note that I 15 disagreed with the points then and I disagree with them 16 nov.
I think that is not an unreasonable characterization 17 of the Commission 's order in TMI unit one on hydrogen, but I 18 am not sure that it is useful for the present discussion to 19 reiterate on each side why we think these things.
20 CONNISSIONER GIIINSKY:
Well, I will tell you why 21 I raise it, and not to go over the old ground again.
It is 22 because it means you can't, I don't know whether it will 23 come out on this subject, but you seem to be ruling out 24 measures to control hydrogen more or less on general grounds 25 and on the f act that we have experienced an accident in
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18 1 which substantial hydrogen was generated and that would seen 2 to be a reasonable thing to guard against.
Do 3 misinterpret you?
4 CHAIRMAN AHEARNE:
Which of us are you addressing?
5 COMMISSIONER GILINSKYs Well, I don't know, either 6 one of you.
7 COMMISSIONER HENDRIE What we said is that those j
8 matters are litigable under part 100.
If you can show that 9 the part 100 guidelines would be exceeded by some sequence 10 which involves hydrogen evolution in particular, then among 11 other things it is reasonable to consider measures to deal 12 with tha t hydrogen evolution.
j 13 Our problem at the time I will recall fo'r you was 1-4 chat there was a question of whether to withdrav 50.na and 15 thus withdraw the astablished design basis for hydropa7 16 control systems or whether to leave that design basis in 17 place for the value which it did still have in the process
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18 and to supplement it by allowing specifically litigation on 19 the hydrogen question under part 100, and I think we vent 20 the right way.
21 COMMISSIONER GILINSKYs Well, let's hear what 22 Dennie has to say.
23 (Next slide.)
24 MR. ROSSa This is more elaboration on the point 25 as to whether lessons learned from TMI should reduce the 4
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The left side of this slide is some different 2 failure sequences like large and small 10CA or various 3 transients.
The right half of the slide is some of the 4 preventive measures that have come since Three Elle Island, 5 some of the so-called lessons learned.
There is a catch-all 6 at the bottom that applies to all of them, like the shift 7 technical advisor, shif t turnover procedures, training, 8 simulator training and operating licensing measures.
Then 9 some of the specifics are requirements, not all of these l
10 have been implemented yet by the way, requirements to test 11 the relief and saf t t.y valves, being to detect the 12 pressurizer level even with on-site power, direct indication 13 of valve position, training subcooling meters, better 14 feedwater systems, and so on.
15 This is an elaboration of why we think the 16 likelihood of. getting degraded core accident sequence is 17 less.
18 Next slide.
19 (Next slide.)
20 The Ccamission has seen this slide for reminders 21 of the bulld-up.
In the ordinate is the volume percent 22 uniformly mixed in the containment and the abscissa being 23 the percent metal water reaction with the ordinate being 24 indexed at the burn and detonation lower limits for hydrogen.
25 COMMISSIONER GIIINSKYs Which are those now?
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1 MR. ROSSs I am sorry?
2 COMMISSIONER GILINSKY:
The little bars?
3 MR. ROSS:
The 4 to 74 I believe is the burnable 4 and detonation is somewhere from 18 to 59 percent.
5 Now, those limits are ideal in that the persence 6 of steam would substantially alter them.
You can cross plot 7 that.
8 COMMISS70NER KENNEDYa Which,is almost assumed, 9 isn' t it?
10 MR. ROSS:
It should be, yes, sir.
You can 11 contdive sequences that would lead to degraded core like an 12 interf acing LOCA that would let steam outside the 13 containment somewhere and then open a PORY or something and 14 let hydrogen out.
You could contrive instances with dry 15 hydrogen.
I wouldn't think they are likely, but they are 16 not zero.
Of course, the significant thing is that for any I'7 given metal water reaction the MARK I's and II's have much 18 highe; concentration.
19 The next slide.
20 (Next slide.)
21 The next three slides respond to some questions 22 that the Commission had asked at several places.
We have 23 done calculations over the last few months on safety factors 24 of containment.
We see on this first slide here a spectrum 25of calculations done for Zoin, Indian Point, Sequoyah and l
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It looks like a ball park of two and a half to 2 three is a good saf ety f actor f or containment.
I need to 3 qualify these safety f actors.
Tuer are uniform static 4 load.
They are not dynamic loads.
5 The design pressure for these containments varies 6 marketedly.
Sequoyah's design pressure is 12 pounds gauge, 1
7 Mcguire's is 15, and the large dry containment are up in the 8 50 or 60.
The numbers that you see there are multipliers of 1
9 design pressure where you would expect the containment to
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10 either yield en lef t, or the metal column, or to fail in th e 11 right column.
12 Now, there are some qualifiers on these 13 calculations that follow on the slides to f ollow.
14 CHAIRMAN AHEARNE:
Wait.
So you point is that 15 they are all designed roughly with the same safety f a ct or
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16 against yield and roughly this estimated safety factor 17 against failure?
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The design turns out that way.
- Well, 19 the question comes up, remember one of the decision elements 20 is, when do you need additional measures.
If you concluded, 21 for example, that you could have a stoic emetric burn and 22 still not exceed the yield pressure, then you might conclude
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23 nothing more is needed, and for a large dry containment th a t 24 is what would happen.
25 CHAIRMAN AHEANE:
You would need a lot more than
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22 1 just-this safety factor to get anywhere.
2 MR. ROSS:
The ultimate, of course, is to retain 3 the integrity in term of leak tightness.
That is the 4 qualifier that is coming up on the next page is that these 5 calculations are relatively primitive and there are 6 discontinuities and there are penetrations that are anchored 7 in maybe an outer shield wall and they penetrate and enter 8 containment' and the relative displacement could produce LOC A S yielding and 10CA leakage.
It is this area where not much i
10 is k nown.
11 CHAIRMAN AHEARNEs
' dell, also the potential 12 pressures you have is significantly different across those 13 various types of containments.
14 MR. ROSS:
The absolute pressure, right.
If you
-15 put the failure pressure and not the safety factor, then you 16 would see numbers like 40 to 42 pounds for Sequoyah and up 17 well over a hrndred for the large drys.
18 I would like to discuss some of the qualifiers 19 that are mentioned on the next slide.
20 (Next slide.)
21 The structural analysis people point out they feel 22 relatively confortable in terms of integrity staying below 23 yield which would mean that the ultimate pressure load would 24 probably in order to feel comfortable as a regulator would 25 take a lot more research, scale model testing and so on.
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23 1
The areas'that are not rigorously analyzed are 2 mentioned in point No.
2, the penetrations that are anchored 3 at diff erent places.
4 There is a modest amount of research in technical 5 assistance programs in this area.
The Ames laboratory 6 consultant has done some of the calculations for Sequoyah 7 and Ncquire.
los Alamos is doing Zion and Indian Point.
8 Now, the uncertainties, as I mentioned, integrity, 9 leak tight integrity at or beyond the yield point we are not 10 comfortable with at this time.
We don't think you can 11 accurately compute it or predict it.
There is little or no 12 da ta on the behavior of the liner and the weld materials 13 and perhaps even the way the liner is anchored to the 14 concrete.
Again, if we could keep it below yield we would 15 f eel relatively comf ortable.
16 We expect that this will be the subject, and I 17 vill mention it in a few minutes, of an additional research 18 request.
19 The final decision element had to do with 20 mitigating measures.
21 let's go to the next slide.
ZZ (Next slide.)
23 Again, this is a slide that the Commission has 24 seen before.
You could inert with nitrogen.
You could have 25 a halon suppression system that would be activated on need.
.1; ALDERSON REPORTING COMPANY, INC.
24 1 If you had some detection like an adequate core cooling 2 datection, undesirable superheat or maybe a hydrogen monitor
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3 reading off scale or something you could activate the halon 4-system.
5 The filtered vented system is one of the more 6 exotic system that would be part of the long-term rulemaking 7 study.
8 CHAIRMAN AHEARNE:
Why do you call it an exotic 9 system?
10 MR. ROSS:
Well, the concept had been specifically 11 considered and turned down some time ago.
12 CHAIRMAN AHEARNE:
Is that the reason' it is an 13 exotic system.
(Laughter.)
14 ER. ROSSa Well, yes. ' I think one of the 15 ingredients is requiring maybe some decisions on the 16 operator as to the course of the accident.
Could the stored j
17 energy in the compressed fluid be released, and then the 18 fission product release is assumed to come sometime later
-19 where you could let out all the stored energy.
20
_The first safeguards policy statement ever issued 21 came from the ACRS in 1964, and I guess Dr. Hendrie was,on 22 the ACRS.
You were not.
In essence they didn't call it 23 filtered vented containment system, but that is what it 24 w as.
It could require some decisions about release energy
.3 now but-don't release fission products later, or when would l
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25 1 you activate the. system.
It also has a potential for 2 letting out stuf f tha t doesn ' t filtered.
We have licensed 3 one.
It would take a lot of experimental analysis work to 4 do it and to that degree I think exotic is the word.
5 COMMISSIONER HENDRIE:
We have got approximately 6 the equivalent out there at Fort St. Ring where if you get a 7 vessel breach why you get rise in pressure in the 8 containment building, but it is a confinement building 9 really more than a containment and the pressure is relieved 10 through louvers when then presumably swing shut, and by the 11 time you would see any fission products why you haven 't got 12 very much leakage because they maintain a suction on the 13 building and run ever *hing through a filter.
14 I will note for the historians that I dissented as 15 an ACES member from that concept long, long ago.
The scheme 16 here is if you get LOCA or something like that it 17 pressurized the containment, and you look at the situation 18 and you say, well, I have all tnese gases steamed in the 19 containment now, but I don't have many fission products at 20 the moment, just f aily lov level stuff that was in the 21 prim ary water.
I as worried about what might happen down 22 the line, and so why don't I start venting the containment 23 excess pressure now and take the small releases ---
24 COMMISSIONER GILINSKY:
But you don't have any 25 hydrogen than either.
COMMISSIONER HENDRIE At that point you don't ALDERSON REPORTING COMPANY, INC.
26 1 have any hydrogen either.
What you are doing is to create a 2*a capacity f or subsequent hydrogen evolution without release.
3 COMMISSIONER GILINSKY:
But wouldn 't you in the 4 meantime be using sprays or something like that?
5 COMMISSIONER HENDRIE:
Oh, yes, sure.
6 COMMISSIONER GILINSKY4 So it just keeps the 7 pressure down so the hydrogen wouldn't be adding very much 8 to it; is that the idea?
9 COMMISSIONER HENDEIE:
Well, it would carrying it 10 way up into a dangerous range.
11 MR. DENTON:
A fundamental issue we are 12 confronting in ongoing looks at design at Indian Point is a 13 rate of energy addition of hydrogen.
The removal capacity 14 of containment systems is normally about a hundred million 15 Btu's an hour, something like that.
The possible heat 16 addition by combusion of hydrogen is on the order of 400 17 million Btu 's.
So you can't wait until the containment is
's i
18 fully pressurized and then start trying to take this heat
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19 ou t.
There are studies going on, as Commission Hendrie 20 said, to vent the containment before the hydrogen burn or 21 recombination could start.
So it is a rate problem.
22 MR. ROSS:
Okay, next slide, please.
23 (Next slide.)
24 Some related research.
i 25 COMMISSIONEH HENDRIE:
Dennie, before you go on l
(
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27 1 off on that other one, we ought to note that with regard to 2 potential methods for improving hydrogen management 3 capability there are some things which don't deal directly 4 with hydrogen but deal wt Lh your ability to remove heat from, 5 the containment, on the one hand, or reduce the likelhood of 6 having hydrogen on the other.
So that in the broadest sense 7 hydrogen management capability goes beyond just these 8 specific things which would deal with hydrogen if you got it.
t 9
MR. ROSS:
Yes, sir, these are definitely 10 consequential measures.
The presented the existence and now 11 try to control it.
Yes, sir, that is right.
12 In the r'escarch area we are having discussions 13 with the Office of Research on two categories of users 14 request, a short-term which would ccver the next six to nine 15 months, say, and then a long-term request for research that 16 would support the final rulemaking which includes studies of 17 the core retention devices and the filtered vented 18 containment system.
19 Probably of more interest is the short-term work 20 that we are going to try and get from research and-through 21 technical assistance or some combination thereof and to get 22 a quick evaluation of one of the last bullets on the 23 previous slide that had to do with hydrogen combustion.
24 Both TVA and we are seriously considering the merits of 25 distributed ignition sources.
There may te some side ALDERSoN REPORTING COMPANY, INC.
28 1 effects that are deleterious and we hope to explore that 2 rather vigorously in the next few months.
This will be a 3 cooperative venture between us and research.
We should have 4 the details on that and I hope to finally sign in the next 5 couple of weeks.
Meanwhile we are having informal 6 discussions and negotiations with what we believe would be 7 the principal contractors.
8 In fact, one of the research results that has 9 already cuisinated is a rather extensive handbook on 10 hydrogen combustion and all of its glory.
TherIe is a copy 11 there in a draf t f orm, " Behavior of Hydrogen During 12 Accidents In Lightwater Reactors."
At a first glance it t
13 looked like it might be very useful to us in making some of 14 these short-tera decisions.
15 The next slide, please.)
16 (N ext slide.)
17 In the table of contents I mentioned related i
18 topics.
There are four:
the interimrule, which 1 have 19 already discussed and should be up here next month; the 20 final rule, there should be an advanced of rulemakir.o out 21 relatively soon this summer.
We are in the final review 22 process.
That rulemaking process will take a couple of 23 years.
We are considering whether to recommend to the 24 Commission that degraded core coolant of which hydrogen 25 management would be a subset should be an unresolved safety ALDERSON REPORTING COMPANY, INC.
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1 issue.
2 COM.YISSIONER GILINSKYa Let me understand.
The 3 interim rule describes the requirements during the period 4 th a t a rule is developed, is that right, the final rule is 5 developed?
6
- 58. ROSS:
That is right.
There are several items 7 that would include operator training and what to do for a 8 degraded core.
It would mandate early MARK I's and II's.
9 It would mandate some studies on some of the others, and I i
10 believe there are six principal features.
It would sort of 11 be like two Aspirins until tae doctor came.
Interim is the 12 key word to.it.
13 We have mentioned a specific related topic, the 14 Zion and Indian Point, and hydrogen ianagement is certainly 15 an issue there.
16 (Next slide.)
I'7 The last ' slide is the conclusionary slide which 18 integrates I hope the decision elements with the containment 19 type.
The first real likelihood, il you read across, it 20 looks like for the different containment types, which of 21 course are also the different reactor types, there doesn't 22 seem to be any difference in the' likelihood per reactor year 23 of having a degraded core, again within the margin that one 24 can quantify things.
25 The' flow on the row No. 2 hydrogen concentration P
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30 1 from left to right is from high to low because the 2 containment is getting bigger, so tae dilution is more.
3 This would tend to say the containment types on the left are 4 in more need of hydrogen management than the containment 5 types on the right.
6 The structural problem from the calcultions that 7 ve have dona, if you combust ot'.ainable, that is obtainable 8 in the sense of TMI mixtures, for the first three 9 containment types you could have a structural response 10 problem, the problem meaning at or above the yeild point.
11 Again, this is a feature of how one specifies the 12 calculation.
If you specify that I release hydrogen like 13 was obtained from the Three Mile Island event and have no 14 combustion until you have released all of this hydrogen, 15 then that is how you would put the word problem in.
16 Mitigation measures for MARK I and II, we point 17 tha t these exist and beyond that we don't know.
18 CHAIRMAN AHEARNE:
Dennie, before you pass over 19 that.
In a chart that had been provided in an earlier 20 briefing I would have reached the conclusion that the 21 subatmospheric plant was in a separate category from the 22 MARK III and ice condenser.
I would have reached the 23 conclusion in talking about structural response that the 24 MARK I and II were one category and MARK III and ice 25 condenser were another category.
It seems to indicate that ALDERSoN REPORTING COMPANY. INC.
31 1 MARK I and II and ice condenser and MARK III are all the 2 same.
3 MR. BUTLER It is with respect to the hydrogen 4 concentration that they are the same.
However, since the 5 subatmospherics have a higher design pressure, 45 psig 6 versus 15 psig f or these other smaller containments ---
7 CHAIRMAN AHEARNE:
MARK II is also 45, isn't it?
8 MR. BUTLER:
The MARK II is indeed also u5.
9 COMMISSIONER HENDRIE:
Yet, but the volume is a 10 lot smaller.
11 MR. ROSS We pointed out in our original paper 12107 that you could take a hundred percent metal water 13 reaction on a subatmospheric containment if you could 14 demonstrate a f actor of two safety margin over design 15 pressure.
16 The conclusion of the last slide, the botton line 17 both of the slide and of the staff position is that we 18 continue t,o believe that MARK I's and II's require 19 inerting.
We will skip the ice condenser for just a 20 minute.
Then the MARK III, subatmospheric and dry we state 21 nothing more now.
22 CHAIRMAN AHEABNE:
The mitigation measures that 23 exist, you are talking about 24 MR. ROSSs Inerting.
l 25 CHAIRMAN AHEARNE.
Inerting.
So that exists for li.
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i 32 1 aost of the MARK I's?
2 HR. ROSS:
The technology exists.
There may not 3 be valves and stuff at Vermont Yankee and Hatch to do it, 4 but they know how to do it, especially Hatch since their 5 sister reactor is inerted.
6 CHAIRMAN AHEARNE:
The MARK II's and MARK III's 7 are they substantially different in the sense of the 6 difficulty of inerting the two?
9 MR. ROSS:
In my understanding the III is markedly 10 diff erent.
We would not state that the technology exists 11 for. the M ARK III.
12 CHAIRE'AN AHEARNEs You would for the MARK II?
13 MR. ROSS:
We would for the II.
14 I skipped over the ice condenser bottom line.
15 Some of the points that we feel about the ice condenser is 16 that there have been many improvements derived from the 17 action plans which of course is jus t a summary of many 18 improvements that came before, lessons learned, bulletins 19 and orders and so on.
20 CHAIRMAN AHEANE:
Those kinds of improvements 21 though are across the board on all types?
22 MR. ROSS:
Yes, sir, that is correct.
23 We believe it did recult in improved safety margin 24 for the ice condenser plants relative to what they were 25 bef ore, in particular being able to recognize a severe ALDERSON REPORTING COMPANY, INC.
p sJ w I accident or the onset of problems and perhaps the G 2 inadequate core cooling.
3
'de have looked at the factors that would 4 disincentive f or inerting the ice condenser and in 5 particular to the maintenance problems associated 0 6 ice itself.
That appears to be a significant disin 4
7 if you had to inert it.
You could not get in as ea 8 the process of inerting and deinerting would be del.
9 to the ice.
10 CHAIRMAN ANEARNE:
Pardon me, would be wh/
11 MR. ROSS:
It would affect the subliminat.
12 the ice.
It would be flowing through the ice chest <
13 In terms of requirements we believe that 1 14 condenser class of plants is generally acceptable fe 15 f ull-time opera tion with respect to hydrogen measur 16 However, we also believe, and it ma} appear to be a' 17 but I don 't think it is, that there are probably so-18 interim' measures that could be taken on ice condensq 19 would increase the safety margin of these containme(
20 As I described a minute alo on the researd 21 efforts, we are looking at a short-term stud y to ind 22 the efficacy and acceptability of these features.
d 23 to look closely at the pros and cons of inerting an@
24 filter vented systems throughout the process of the 25 rulemaking.
l ALDERSON REPORTING COMPANY. INC.
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1 As far as the conbustion process, that is th, 2 distributed ignition source, we intend to look at it l
3 especially and TVA is also.
TVA has been looking at t l
l 4 very same questions.
They have made presentations to l 5 ACRS earlier this month on this subject.
6 We believe, and these are from conversations 7 have had with TVA people almost daily, that they have i
8 narrowed down their consideration to tuo features.
On 9 feature would be a distributed ignition source that ha 10 by side with it a hydrogen sensing or hydrogen detectos 11 appears that if you install this in the interim and vi 12 perhaps a relaxed criterion on seismic qualifications )
13 redundancy and diversity until the completion of the 1-4 long-term rulemaking on degraded cores that this would 15 increase in safety margin.
16 I think the same logic would apply here that 17 did on the M ARK I's and II's.
This type of instrument 18 probably readily available and it is probably relativel 19 cheap.
Certainly the hydrogen detector is.
For that E l.
20 it would appear that on a cost-benefit ratio that this 21 feature of distributive detection and ingition instrumc 22 would probably be a safety benefit.
23 We think we ought to look into it quickly.
2 24 retaining consultants in terms of primarily Sandia, anf 25 between us and the Office of Research we think we can 6 ALDERSON REPORTING COMPANY, iNC.
35 II down the pros and cons of this issue very quickly.
We 2 expect to have neetings to this end next week and we have 3'had daily phone calls to this and.
4 CHAIRMAN AHEARNE:
You said you felt they had 5 narrowed it down to two possibilities instead of one.
6 MR. ROSS:
They were looking into the halon system 7 also.
I an informed that in the last few days apparently 8 halon dropped off as something that could be done in a few 9 months.
I don't know if that was economic or availability 10 or both.
11 COMMISSIONER HENDRIEs I was going to ask Dennie 12 do we know what some of the pro and con a*rguments were on l
13 the halon system?
14 MR. ROSSs On halon, of course, it is expensive, 15 but I guess expense is a state of mind.
If you have got a 16 three billion dollar plant and a three million dollar price e
l'7 t a g for halon, maybe three million is not expensive.
It 18 does have a personal hazard, that is, you wouldn't want it 19 go off while you were in the containment accidentally, i
l 20 although I don't see any reason why this halon system 21 shouldn 't be manual.
I don ' t know any reason to automate it.
22 COMMISSIONER HENDRIEs I thought you had some j
23 minutes to walk out without significant physiological harm.
24 MR. ROSSs It is up to 20 percent concentration 25 which would probably be the recommended concentration.
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1 There is apparently some chemical reactions, and I know of 2 people who have worked with Freon that worry about this and 3 anybe at high temperatures it breaks down into some bad 4 acto rs, high temperatures like eight or nine hundred degrees.
5 MR. DENTON:
Of course, it doesn't get rid of the 6 hydrogen either.
7 COMMISSIONER HENDRIEs It just suppresses it.
8 MR. ROSSa Right.
9 MR. RUBENSTEIN:
I was going to point out that the i
10 fluoride ion may be deleterious to the primary system is you 11 had.a spurious activation of the system and it does involve 12 like 90,000 pounds of halon being put into the system.
We 13 are not quite sure that we know all about it that we sant to 14 know about how it.
15 '
MR. ROSS:
I think a problem like that could be 16 worked out though.
Those are not serious problems.
I think 17 probably it is the timing more than anything else.
18 What we expect to happen over the next f ew weeks, 19 we expect the TVA to be more firm as to what they are going 20 to propose and we are going to be more firm as to what we 21 would accept and hope we can come to closure on the issue of 22 whether distributt._ ignition sources are both desirable and 23 perhaps even necessary for the ice condenser.
24 CHAIREAN AHEARNE:
Now, Dennie, if you reach that 25 conclusion with respect to Sequoy'ah, then I would presume ALDERSoN REPORTING COMPANY, INC.
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37 1 that equivalent conclusion would be reached with resect to 2 Cook.
3 MR. ROSbs It could be.
The Cook containment is a 4 reinforet' ;,.,ncrete and you might argue different strokes 5 for that.
We haven't discussed it, and as far as I know 6 there has been no dialogue with Cook, but they can take on 7 hydrogen.
8 CHAIRMAN AHEANE:
They can, pardon me?
9 MR. ROSS:
They can take more hydrogen because 10 th ey have a stronger containment.
11 MR DENTON:
They also have a so-called bottom 12 spray ring that the' Sequoyah doesn 't ha ve that also gives 13 them a bit more protection.
Certainly that would flow.
I 1-4 think we are looking at the margin here.
When we went into 15 this we didn 't think we could develop the pros and cons from 16 a safety point as quickly as we apparently are able to do.
I'7 I guess the first c oncern is to be sure we don't put in 18 something or require something or encourage something that 19 makes the plant less saf e.
I want to be sure we don't start 20 that.
21 If it is going in the right direction then we need 22 to ask ourselves and are asking ourselves should we 23 encourage the ' insulation of systems which don't meet all the 24 saf ety criteria for seismic or equipment qualifications or 25 aging.
If it certainly goes in the right direction it is
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1 better to have it during a year while we study it further to 2 get in a proper system working.
3 CHAIRMAN AHEARNE:
When you say that Cook is 4 stronger, is it at the Mcgu; te end there?
5 MR. ROSS:
It is a steel lined reinforced concrete 6 as opposed to the Sequoyah which is just steel.
7 CHAIRMAN AHEARNE:
For example, Walt had provided 8 I guess the last time a table under ice condenser and design 9 pt:essures, f ailure pressures, et cetera.
Where would Cook 10 fi t, at the upper end of that?
11 MR. BUTLER:
I am sorry, I don't recall the design 12 pressure for Cook.
It is either or 12 or 15.
I think it is 13 15, but I would have to check the record.
14 CHAIRMAN AHEARNE:
Well, the range is 12 to 15 on 15 ice condensars.
16 HR. BUTLER:
It is one or the other, but I am not 17 sure which at this time.
18 MR. DENTON:
With regard to Sequoyah I think they 19 anticipate initial criticality in the first week of July, at 20 least five or six weeks above our testing.
21 CHAIRMAN AHEARNE:
They don 't he.ve approval for ZZ full power, right?
23 MR. DENTON:
Of low power testing.
24 CHAIRMAN AHEARNE:
I know.
25 MR. DENTON:
That is right.
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CHAIRMAN AHEARNE:
In the paper you sent up, 2 Harold, you mettioned that the methodology, and I assume you 3 are referring to the methodology that both the probabilistic 4 group and also Roger Matson's group used didn't give credit 5 for the amount of energy transferred through the steel dry 6 vell and torus.
7 MR. ROSSa They did not because a system for doing 8 that does not exist.
It is not plumbed in.
In the Sequoyah 9 design there is a free-standing steel containment and then 10 an annulous and then a concrete shield.
You see, this 11 transient f ails due to steam overpressure of as many hours.
12 An ad hoc procedure could be to spray the thing with water 13 with fire hoses.
This would probably be very effective in 1-4 reducing the pressure, but you can't take credit for it.
15 MR. RUBENSTEIN:
Or increasing the strength of the 16 containment.
17 MR. DENTONa or you could install a spray system 18 in advance.
19 HR. ROSSa We discussed this with TVA and 20 presumably they have either have or are considering it, one 21 of the other.
i 22 One final feature is a side effect of the recent 23 report that we got from Sandia that illustrates the 24 potential benefit of a distributed ignition system.
If you 25 start burning hydrogen on the threshold of the burnable
!!]
ALDERSoN REPORTING COMPANY, INC.
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..s e 1 concentrations you may get only half of the combustion that 2 you would get if you waited a little bit longer.
The chart 3 on this report shows that at 10 percent hydrogen 4 concentration you would expect essentially get full 5 combustion, but at 8 percent you might only-get half.
So 6 this incomplete combustion is bound to have an overall 7 safety benefit somewhere down the line.
8 MR. DENTON:
I guess overall for the ice condenser 9 class I feel like our understanding of mitigating systems 10 and their pros and cons is rapidly increasing because of 11 TV A 's cooperative attitude in this regard.
12 FROM THE AUDIENCE:
We can'.t hear you.
13 MR. DENTON:
I think in the area of the ice 14 condenser our understanding of mitigating systems is rapidly j
15 changing because of TVA's. attitude in this regard.
They are 16 studying all these possibilities.
We are learning a lot and I'7 I would propose that we decide that issue in the course of 18 coming back to you on Sequoyah specifically.
19 COMMISSIONER GILINSKYs I don't have any questions 20 on this, but I was going to return to part 100, if you could 21 stand it.
22 (Laughter.)
23 MR. ROSS:
If I could squeeze in the announcement, 24 this concludes the staf f presentation.
25 (Laughter)
ALDERSON REPORTING COMPANY, INC.
4 41 I
1 CHAIRHAli AHEARNE:
Before Dennie leaves Sequoyah, 2 though, since you have visited it 3
COMMISSIONER GILINSKY:
Well, I would just on the l
4 basis of my own brief discussion with TVA second what Harold 5 has said.
I was there to take a look at the f acility, but 6 did have a discussion on this subject with them'and found 7 TVA working very hard on the problem analyzing the various 8 approaches and taking what I thought was a very commendable j
9 approach and attitude.
10 CHAIRMAN AHEARNE Dick, did you have any 11 questions you wanted to ask on this?
12 COMMISSIONER KENNEDYa No, not now.
13 CHAIRMAN AHEARNE:
Joe?
14 COMMISSIONER HENDRIE:
I guess not.
15 CHAIRMAN AHEARNEs Peter?
16 COMMISSIONER BRADFORD:
No.
e 17 CHAIRMAN AHEARNEa Before you get to your part 100 18 discussion which I don't think referred to Dennie ---
19 COMMISSIONER GILINSKYa No, although I am 20 interested to what extent the outcomes are affected by'the 21 Commission 's decision.
Where does that impinge on how you 22 are coming out?
23 MR. ROSS:
On ice condensers I don't think it had 24 any effect because Sequoyah is doing what it is doing.
On 25 Hatch and Vermont Yankee I think the only thing that will 5 I ALDERSON REPORTING COMPANY, INC.
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42 e+-
1 get them inerted, which is our recommendation, is a rule 2 that permits it.
We will have a rule up here in a month 3 that would do that.
The only other regulatory authority 4 that we could would be to presumably to somehow interpret 5 part 100.
Now, we haven't done that.
If we were looking 6 for regulatory authority to compel inerting absent a rule 7 that we are proposing, then I guess we would have to look at 8 part 100 somehov.
9 CHAIRMAN AHEARNE:
But, of course, the Commission 10 hasn 't reached the conclusion yet that they ought to be 11 inerted.
12 MR. ROSS:
It affects the MARK I's and II's but it 13 does not af f ect the ice condenser in my opinion.
14 COMMISSIONER GIIINSKY:
The point I was going to 15 make about part 100 which as I understand the way it works, 16 and I am sure, Joe, you understand it better, I think you 17 applied it vigorously for a number of years, is that you 18 assume that there is a certain quantity of radioactive 19 material in the containment and go on and eticulate from 20 th ere.
Now, that is not related in any specific way to a 21 particular accident.
It is just a general assumption of a 22 certain f raction of fission products.
23 COMMISIONER HENDRIE:
That is right.
In the 24 conventional analysis, the classical analysis that we have 25 done we say look to examine whether you have proposed the L
ALDERSON REPORTING COMPANY, INC.
s 43 1 containment that it is tight enough and has a low enough l
2 leak rate.
We will simply assume this atmosphere full of 3 fission products corresponding roughly to a full core melt 4 and then with certain established assumptions we will 5 calculate off-site doses from the leakage and see how that 6 looks.
Indeed, within that framework there is no particular 7 mention of hydrogen or no hydrogen.
You are calculating 8 doses from fission products.
9 What we have done in the TMI I, in the answers to 10 the questions certified to us, is to say that we believe 11 that questiens about hydrogen in which hydrogen evolution 12 becomes a significant element in the possible release of 13 fission products by causing containment failure or whatever, 14 that that is in our view a litigable subject under part 100.
15 Now, saying that doesn't confirm the direction of 16 the argument just to that rather strict and artificial dose l'7 calculation that the staff classically does according to 18 reg. guides 1.3 and 1.4 and for part 100 cite guideline 19 conformance, but rather leaves it to the parties want to 20 bring the arguments how they will pursue those.
21 Now, let me see if I can got a nod out of the 22 counsel's end of the table for this explanation and maybe we 23 ought to ask if. there is anything want to edit.
24 COMMISIONER GILINSKYs What I was going to say is 25 you can't have that quantity of radioactive material without IS ALDERSON REPORTING COMPANY, INC.
44 I at the same time having generated a rather large amount of 2 hydrogen corresponding to it.
3 COMMISSIONER HENDRIE:
In the real world I think 4 that is probably correct.
A water reactor is going to have 5 enough steam in it so that if you get that kind of fission 6 product inventory out you will probably have made a lot of 7 hydrogen.
I am just saying that I don't think that any 8 litigation under the Commission's order on TMI I would be 9 confined or bound by that sort of prescribed dose 10 calculation that the staff does under reg. guides 1.3 and 11 1.4.
12 COMMISSIONER GILINSKY But it sounds like you are 13 not letting someone say simply, Look in part 100 you use 14 this much radioactive material and corresponding to tha t is 15 a quantity "X"
of hydrogen.
16 COMMISSIONEE HENDRIEa I think you could let them 17 make that argument, but if I were their technical adviser I 18 would advisa them to make a more considered argument than 19 tham because for years we have done this rather anomylous 20 fission product assumption in the containment as a way of 21 testing the. containment design basis.
22 COMMISSIONER GILINSKYs I mean, that was not tied 23 to any specific accident.
As it turned out in retrospect 24 that even thought it was a more or less arbitrary approach 25 it was a good thing that we had it and we stuck with it 4
ALDERSoN REPORTING COMPANY, INC.
45 r
1 because had we gone consistently with the approach that you 2 don't consider accidents involving core melt we might have 3 ended up with no containment at all.
4 COMMISSIONER HENDRIE.
No.
I think you would have 5 had to have a containment, but its leakage rate might have 6 been substantially higher than unit II was and that would 7 have been unfortunate.
8 COHHISSIONER GILINSKY.
Where this brings me is 9 that it seems in designing safety systens there is something 10 to be said for putting in measures and in a sense hedging it 11 against 'certain contingencies and not necessarily tying 12 those up to specific scenarios but using certain general 13 principles like part 100.
14 COMMISSIONER HENDRIE I am compelled to agree 15 with you since I have argued precisely for that sort of 16 philosophy many times in the past and that is the way in l'7 general that the rags are set up, you know, the general 18 design criteria.
There are some of these overlaps.
In 19 f a ct, we have had arguments with the Appeal Board about 20 whether the overlaps in requirements were in fact permitted 21 and intended by the regulations.
The Commission has 22 generally come down on the side of conservatism, that is, 23 saying, yes, you can have one regulation tha t rays the 24 system has to limit the damage to two percent.
Then you 25 have another system that says, let's assume the damage is
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l five percent or something beyond it.
Then when you get to 2 the containment why there is yet another process that says, 3 boy, let's assume the core just dumped its fission products 4 into the atmosphere and nov let's see what kind of a leak 5 rate is allowable in view of the site distances and 6 meterological conditions in the area.
7 COMMISSIONER GIIINSKY:
That is why in view of our 8 experience it seems to me to make sense to protect the 9 fairly sizeable amount of hydrogen generated.
10 COMMISSIONER HENDRIEs I think parties are free 11 under the order if they wish to make that argument.
All we 12 have really done is to say you have to make it in the 13 context of part 100 rather than under an altered 50.44.
I 14 think va vanted to retain 50.44 because there are some 15 design features that end up being required under 50.44, and 16 if you just removed it you would leave yourself in peculiar 17 f ashion to regulate those design f eatures.
So I think it 18 was desirable to keep it, but we have allowed the litigation.
19 CHAIRMAN AHEARNE Clearly the reason-ve have the 20 staff going through all this on these various containments 21 is on that general approach.
22 COMMISSIONER HENDRIE:
Presumably in due time ve 23 vill straighten out on a more sweeping and ra tional basis 1
24 where all of these things ought to lie, and if that had l
25 occurred before then the question in TM1 wouldn 't have come l
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47 1 up about hydrogen.
It would be clear how it was to be 2 treated, but we have to have some sort of interim basis for 3 operation.
4 COMMISSIONER GILINSKYa Well, just as far as the 5 discussion we have had we are moving in the right direction 6 with all of these litigation measures, and I hope we will 7 keep moving forward on this.
8 CHAIRMAN AHEARNEs We had also agreed to give 9 General Electric at their request a short period of response.
10 (Short pause.)
11 CHAIRMAN AHEARNE:
If you will identify yourselves.
12 MR. BUCHHOLZa My name is Robert Buchholz.
Steve 13 Stark and I are here today to represent GE to argue against 1-4 the staff recommendation to require inerting of MARK I and 15 II containments on an interim basis during the rulemaking 16 proceeding.
17 As evidenced by our previous discussion on March 18 19th, I think you will recall, and the several letters that 19 have been transmitted back and f orth i that interim 20 period ---
21 CHAIRMAN AHEARNE:
I would recommend that you 22 assume we both remember and have read.
23 MR. BUCHHOLZ Okay.
I think we have in our 24 presentation here.
We consider this to be an area of 25 significant concern to us.
We are here today to spend a few ALDERSON REPORTING CCMPANY, INC.
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1 minutes to amplify and supplement our previous comments and 2 comm unications with you.
3 We have two charts and they have not been handed 4 out to you previously, but I believe they are in back of the 5 screen somewhere, and I will pass them over to your side of 6 the table.
7 (First slide.)
8 I think it is fair to ask the first cuestion as to 9 why are we struggling against this inerting recommendation 10 of the staff so arduously?
The answer to that I think is on 11 the.first chart.
12 Specifically the BWR has several de'sion f eatures 13 which mitigate the probability of core uncovery and 14 consequently hydrogen generation.
15 I note that these kinds of design features are not 16 specifically included in the risk assessment thing, and tha t 17 is the reason for highlighting them here today.
For 18 example, the BUR does have redundant reactor vessel water 19 level measurement.
20 If core coverage is threatened the operator will 21 know about it in advance and can take the necessary actions l
22 by ensuring, for example, that the high-pressure injection 23 systems are. operated or by utilizing on the second bullet 24 there the rapid depressurization capability of the ADS 25 system, the automatic depressurization system, to bring on l
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49 1 the low-pressure injections systems.
2 The E'4R is designed to operate with the bubble in 3 the pressure vessel and has strong natural circulation 4 capability both internal and external to the vessel.
This 5 capability is demonstrated, you know, during the start-up of 6 each plant and.thereby we feel eliminating any concern 7 regarding coolability of the core when there is a void in 8 the pressure vessel.
9 In addition to the three bullets there that I have 10 indicated relative to the NSSS, there are design features.
11 Specifically I want to mention the fact that there is a 12 large passive heat sink in the containment of about a 13 million gallons of water which is available to mitigate the 14 consequences of things like a stuck open relief valve and, 15 you know, the more probable types of transients that the 16 system would have to undergo.
I'7 I think this summarizes the reasons and some of 18 the things that we believe are features, not to say that you 19 shouldn ' t to try to further improve the safety levels, but 20 ve want to make sure that these things are focused on when 21 you are considering the need to inert our plants.
22 Now, I think there is no disagreement around the 23 circuit rega rding the fact that inerting yields atsmall risk 24 reduction, and accordingly I won't spend' time to read from 25 the staf f paper that says that.
That has been covered.
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We further expect this belief to be substantiated 2 by studies that we are undertaking as well as Vermont Yankee 3 are undertaking.
We are undertaking these studies in 4 response to the request for the Limerick evaluations, and l
5 Vermont Yankee is sponsoring studies at MIT under Rasmussen.
6 The next two bullets have to do with operational 7 related items that were covered by the Vermont Yankee 8 personnel on March 19th.
The hazard to plant personnel I 9 think has been referred to before because of the possibility 10 of incomplete purging of hydrogen f rom the system.
Of the 11 problems we have talked about today that is probably one of
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12 the more real problems throughout not just the nuclear 13 industry but througout all of industry.
14 The Yankee operations personnel spoke of the 15 advantages of being able to correct operational problems 16 while they are still small and being able to instill into 17 their operational people a positive attitude of prevention 18 in terms of the maintenance capability.
19 I think the staff seconded that motion in the 107A 20 document when they noted that when considering day-to-day
-21 operational aspects we would agree that inerting is a 22 definite disadvantage.
23 What I would like to suggest here is that, first 24 of all, we concur with that and we believe that safety is 25 really built upon the foundation of, you knoa, a p prop ria te ALDERSoN REPORTING COMPANY, INC.'
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51 1 kinds of day-to-day actions.
The kinds of things I think we 2 should focus on are those that are the more probable in 3 nature rather than those that are the less probable in 4 n a t.u r e.
5 As the staff as indicated in their presentation 6 earlier today, those transients or those accidents we are 7 inerting would prove beneficial or several orders of 8 magnitude less probable than the other kinds of transients 9 that would result in containment failure.
10 CHAIREAN AHEARNE:
It sounds that it would be 11 General Elertric's position that the inerting would lead to 12 a decrease in safety.
13 HR. BUCHHOLZa We believe that is the case, yes.
14 CHAIRMAN AHEARNE:
Then would you conclude that 15 the inerting plans are unsafe?
16 MR. BUCHHOLZ:
No.
I thirk there is a distinction 17 between believing that it is a decrease in safety and saying 18 that something is unsafe.
Several of the inerted plants at 19 the time of Three Mile Island were preparing papers to come 20 forth in order to deinert.
They have been distracted 21 somehov from that endeavor, you know, for the last year.
22 CHAIRMAN AHEARNE:
It is not quite the appropriate 23 time to come in and say hydrogen burn is not a problem.
24 YR. BUCHHOLZs It is a little awkward, yes.
25 COMMISSIONER GILINSKY:
What is the situation l
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..s-52 1 abroad, with your plants that you have sold abroad?
2 CHAIRMAN AHEARNE:
You know one is inerted.
I 3
MR. BUCHHOLZ:
Yes, the Tarapur plant is inerted.
4 I believe they are all inerted ab road.
5 C3HMISSIONER GILINSKYs Is this following our lead?
6 HR. BUCHHOLZa No, it is really following our lead 7 here in the United States.
I would expect that they would 8 follow our, lead again if we were deinert the plants, too.
9 (Next slide.)
10 Well, the second chart, and I promise to be brief.
11 With the information that we have just discussed, 12 you know, we have concluded that the staff proposal should 13 not be approved.
We consider that the proposal is 14 prescriptive in nature and that there are other methods of 15 hydrogen control that weren 't f ully considered tha t could 16 possibly not lead to some of the disadvantages that we have 17 discussed.
18 I think we all agree that it is not an urgent 19 saf ety issue.
The staff in their most recent paper stated 20 th a t "We agree that there are no overriding safety arguments 21 to support an inerting decision.".Therefore, I claim it is 22 not an urgent issue.
23 We feel that the basis for the recommendation is 24 shaky at best and inadequate at worst.
We are doing some 25 work, and it is noted in the Vermont Yankee Nuclear Power s
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$3 1 Corporation letter.to you, Chairman Ahearne, on June 19th 2 both GE and VY are conducting additional studies to try to 3 shed,.you know, more definitive light on this subject.
We 4 would earnestly wish that those studies be allowed to come 5 to completion.
6 We ask that the issue be addressed as part of the 7 rulemaking process for this, as I said, will, you know, 8 solicit some additional quantitative input as a result of 9 these studies.
We feel that this request is reasonable and 10 that the timing is consistent with the determination that we 11 have all hai that the situation that we are talking about is 12 a low-risk one.
13 We feel that if it is judged that there is a need 14 to reduce risks further that going this process will permit 15 us to identif y the actions that would reduct the risk that 16 have the least adverse consequences.
17 I think that kind of sums up our position and we 18 would be glad to answer any questions that you have.
19 C3HHISSIONER GILINSKY:
I observe that you seem to 20 be arguing on your first page of your observations on the 21 basis that an accident involving hydrogen generation is 22 unlikely.
The staff seems to be saying that in such an 23 accident other things will happen first and therefore 24 dealing with the hydrogen doesn't help you much.
25 MR. BUCHHOLZ:
I think we are all in accord, l
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..s, 54 1 Commissioner Oilinsky, in just quoting the staff's paper 2 that the accidents that lead to significant hydrogen 3 generation are two orders of magnitude less probable than 4 those that would fail the containment first thereby 5 mitigating any influence of the inerting.
6 I think one of the faults that we have had perhaps 7 over the years is to be working on problems that are two 8 orders of magnitude less important than the problems we 9 should have been working on perhaps.
So I am suggesting
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10 that for that reason there is no urgency to inerting the l
11 NARK I and II containments.
12 COMMISSIONER GILINSKYs We were working on the 13 ones that va thought were the important ones and it turned 14 out that we didn't have it quite right.
We were talking 15 about this a little earlier, the question of to what extent 16 one one ought to hedge against having made some of these 17 calculations incorrectly and estimating the probabilities 1
18 incorrectly, and therefore they have lef t out some important 1
19 considerations dealing with, you know, possible large 20 accidents.
This would be in the nature of a hedge against 21 those kinds of possibilities.
22 MR. BUCHHOLZ s-The think that I guess I would ask 23 you' to consider is the desirability of implementing that 24 h edge, and I understand exactly vhat you are talking about, 25 versus the known undesirability of implementing that hedge.
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SS 1 One of our concerns is that we have to this point in time 2 ncit obtained as good a set of data back from the utilities 3 regarding the the virtues of not being inerted and the 4 adverse consequences of being inerted, and I would like to 5 have those.
6 CHAIRMAN AHEARNE:
Perhaps there aren't any good 7 set of data.
8 MR. BUCHHOLZ:
At this point in time perhaps there 9 is not.
We have supplemented the NRC staff's request with a 1'O set of questions of our own which we tried to learn a few 11 lessons from the staff's set and then provide supplementary 12 quest' ions.
13 COMMISSIONER GILINSKY s It is really a balancing 14 of inconvenience on a day-to-day basis and cost against the 15 value of the safety measure that deals with certain 16 contingencies..That is a balance that one has to make, and 17 I think we are all agreed that that is what is at issue here.
18 MR. BUCHHOLZ Yes.
All we are saying is that we 19 are taking some action to get some further information on 20 that and would suggest that in considering the agreed upon 21 lack of urgency on the matter -- I mean we are talking about 22 implementing this recommendation as an interim action.
That 23 is the context that I am arguing the case.
24 CHAIBMAN AHEARNEs Vic?
25 COMMISSIONER GIIINSKY No.
Thank you.
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CHAIRMAN AHEARNE:
Dick?
2 COMMISSIONER KENNEDYs No.
Thank you.
3 CHAIRMAN AHEARNE Joe?
4 COMMISSIONER HENDRIEs No.
Thankyouverf 5
MB. BUCHHOLZs Thank you.
6 CHAIRMAN AHEARNE:
Thank you.
7 (Whereupon, at 5:00
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8 adjourned. )
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MUCLEAR REGULATORY CO!OiISSION This is 00 certify that the attached proceedir.gs befcre the in the catter of: Discussion of SECY-80-107-Proposed Interim Hydrogen Control Requirements for Small Containments - PUBLIC MEETING--
Date of ?receed_i..g:
June 26, 1980 Decket !!u=ber:
e t C e e r.-
p.
C..s.4, Washington, D. C.
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..-s.s sere held as herein appears, ar.d tha: this is the crigi:.al rs script therecf for the file of the Cc==i;sion.
Mary C. Simons Official Reporter (~yped)
A4_
mm Official Repercer (Signature)
M aOY e