ML20041G506
| ML20041G506 | |
| Person / Time | |
|---|---|
| Issue date: | 03/09/1982 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| Shared Package | |
| ML20041G507 | List: |
| References | |
| REF-10CFR9.7 NUDOCS 8203220409 | |
| Download: ML20041G506 (96) | |
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NUCLEAR REGULATORY CCMMISSION m
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COMMISSION MEETING In the Macar of:
PUBLIC MEETING BRIEFING BY AIF AND EPRI ON PRESSURIZED THERMAL SHOCK
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m: ~ March 9, 1982
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Washington, D. C.
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400 vi:T.::ia Ave., S.W. W==H4 g--
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Telark-=: (202) 554-2345 8203220409 820309 PDR 10CFR PF9.7 PDR
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1 UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION
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3 4
BRIEFING BY AIF AND EPRI ON PRESSURIZED THERHAL SHOCK j
5 PUBLIC HEETING 6
Nuclear Regulatory Commission Room 1130 7
1717 H Street, N.W.
Washington, D.C.
8 Tuesday, March 9, 1982 9
The Commission set, pursuant to notice, at 10 2:30 p.m.
11 BEFORE:
12 NUNZIO PALLADINO, Consission Chairman 13 JOHN AHEARNE, Commissioner PETER BRADFORD, Commissioner 14 VICTOR GILINSKY, Commissioner THOMAS ROBERTS, Commissioner 15 STAFF AND PRESENTERS SEATED AT COHNISSION TABLES 16 SHELDON TRUB ATCH, OGC 17 FORREST REHICK, OPE JOHN H0YLE, Secre tary i
18 DR. CLARK GIBBS, AIF l
JAMES TAYLOR, AIF 19 WARREN OWEN, EPRI DR. DAVID ROSSIN., EPRI 20 DR. V. CHEIAL, EPHI DR. TED HARSTON, EPHI 21 DR. RONMEY DUFFEY, EPRI WILLIAH LAYHAN, NSAC 22 AUDIENCE SPEAKERS:
23 BOB GILL 24 25 ALDERSoN REPORTING COMPANY,INC.
j 6 /.11L fLom N @.GL W4 F/M20 8B33
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DISCLAIMER This is an unofficial transcript of a meeting of the United States Nuclear Regulatory Comission held on March *9, 1982 in the Cocmission's offices at 1717 H Street, N. W.
Wasnington, D. C.
The meeting was open to public a.ttendance and observation.
This transcript
- has not been reviewed, corrected, or edited, and it may contain inaccuracies.
The transcript is iatended. solely for general infomational purooses.
As provided by 10 CFR 9.103, it is not part of the foriul or informal record-of decision of the matters discussed.
Expressions of opinion in
.this. transcript do not necessarily reflect final determinations or beliefs.
No pleading or other paper may be filed with the Comission in any-proceeding as the result of or addressed to any'orize.
statement or argument contained herein, except as tha Comission may auth l
2 1
EEEEEERIEEE 2
COMMISSIONER PALLADIN0s Good afternoon, 3
ladies and gentlemen.
4 The Comaission meets this afternoon to hear 5
from the Atomic Industrial Forum and the Electric Power 6 Research Institute.
These industry groups will provide 7 their view on the subject of pressurired thermal shock 8 and discuss the progress they have made on resolution of 9
the pressurired thermal shock issue.
10 The Atomic Industrial Forum is represented by 11 Dr. Clark Gibbs and James Taylor.
The Electric Power 12 Research Institute is represented by Warren Owen, Dr. A.
13 David Rossin, Dr. V. Chexal, Dr. Ted Earston and Dr.
14 Romney Duffer and William Layman.
15 The Atomic Industrial Forum will provide the 18 first briefing, and the Electric Power Research 17 Institute will provide the second briefing.
18 At this time, unless other commissioners have 19 opening comments, I would propose to turn the meeting 20 over to Mr. Gibbs.
E' MR. GIBBS:
Thank you, Mr. Chairman.
22 My name is Clark Gibbs, Vice President of 23 Middle South Services.
I am also Chairman of the Atomic l
l 24 Industrial Forum, Connittee on Reactor Licensing and 25 Safety, on whose behalf I am here to talk to you today l
l ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W, WASHINGTON, D.C. 20024 (202) 554-2345
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about this particular issue.
2 With me on my left is Jim Taylor, who is the 3
Nanager of Licensing for Babcock & Wilcox.
He is also 4 Chairman of an AIF Subcommittee on Reactor Vessel 5
Integrity, which reports to the Committee on Beactor 6 Licensing and Safety.
7 Because of the organization which I represent, 8
I am going to be reading my remarks from a text.
Feel 9 free at any time to interrupt me with any questions you 10 may have.
11 The industry considers the pressurized thermal 12 shock issue as one of importance not only from a safety 13 but also an economic point of view.
The safety issue is 14 the obvious need to maintain the reactor coolant system 15 pressure boundary.
The economic concern is the 16 importance of avoiding plant outages for the examination 17 and repair of the vessel necessitated by a severe 18 pressurized thermal shock event.
l l
l 19 This is reflected not only in the amount of 20 effort devot+d to the issue within the past year but in 21 terms of relcted activities that have been ongoing for 22 aan years.
In 1981 alone, thousands of man hours and 23 millions of dollars have been spent by utilities and 24 vendors on this subject.
25 While the economic aspects of this are ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE. S.W., WASHINGTON. O.C. 20024 (202) 564-2346
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obviously important, the aspect we are discussing here 2
today is safety, and the remainder of my comments are so 3
directed.
The importance with which we view this 4
issue is also reflected in the work which industry is 5
sponsoring through EPRI, which you will hear more about 6
in a few minutes from my colleagues.
7 From the work we have done to date, we are 8
convinced there is no near-ters safety concern, and we 9
expect to achieve full vessel lifetime in all of our to plants.
11 Because generic and plant-specific analyses 12 performed and submitted to the NRC demonstrate that 13 there is no'near-tera safety concern, we believe that 14 all future efforts should be conducted in an orderly and 15 efficient manner which will optimize the utilization of 16 both NRC staff and industry resources.
We also believe 17 any future work required by the NBC should be planned 18 and executed considering input from industry.
19 In order to provide some background and 20 perspective on this issue, let ne first point out that 21 the concern regarding thermal shock to reactor vessels 22 is not a new one.
Badiation effects on certain reactor 23 vessel materials has been known and understood for quite 24 some time.
25 The underrtanding of these effects, for ALDERSoN AEPCRTING CCMPANY,INC, 400 VIRGINtA AVE., S.W. WASHINGTON O.C. 20024 (202) 554 2346
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example, led the industry in general to reduce the 2
pemissible copper content in materials used in vessels.
3 This change occurred about 12 years ago and is one of 4
the main reasons that today pressuriced thermal shock is c
5 of greatest significance in only a limited number of S
plants.
7 In the aid 1970s, questions regarding thermal 8 shock to reactor vessels of higher copper content were 9 evaluated.
Those evaluations showed that a significant 10 number of years were available before any potential 11 problems would exist on those vessels, and although 12 today's evaluations are considerably more complex, these 13 previous conclusions remain unchanged.
i 14 In the first meeting of the AIF Reactor Vessel 15 Integrity Subcommittee, which, by the way, is a recently 16 formed committee, it became apparent there were some l
17 significant differences in approach taken by each group 18 working on pressurized thermal shock.
We consider these 19 differences to be healthy, and in fact they have aided 20 in our understanding of the problem.
21 COHNISSIONER AHEARHE:
Clark, just as a matter 22 of interest, do you have any foreign members who belong 23 to that?
24 MR. GIBBS4 No, sir, we do not.
25 I believe that one of the main reasons for the AI. DER $oN REPORTING COMPANY. INC.
400 VIRGINIA AVE, S.W., WASHINGTON, D.C. 20024 (202) 554-2345
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con trove rsy surrounding the issue of pressurized thermal 2
shock today is the complex interrelationships among the 3
various technical disciplines that are involved in i
4 addressing this issue.
Today's pressurized thermal 5
shock evaluations must consider fluence predictions, O
material toughness evaluntions, both initial and 7 predicted, thermal hydraulic analyses, and fracture 8 mechanics.
9 When performing these evaluations, the work of to these various disciplines must be tightly integrated.
11 Overly conservative assumptions on the part of any of 12 the individual disciplines can lead to unwarranted 13 conclusions.
Conflicting assumptions can lead to 1^
erroneous conclusions.
15 57 first slide illustrates the many elements 16 that must be integrated to evaluate a pressure thermal 17 shock event.
l 18 (Slide) l 19 The pressurized thermal shock issue was l
20 highlighted about a year ago because analyses performed 21 in response to an NRC staff request employed very 22 conservative bounding assumptions.
Conservatisms were 23 included in the conditions related to the initiating 24 event, the thermal hydraulics, materials properties, 25 flaw characteristics and fracture mechanics.
ALDERSoN REPORTING COMPANY. INC, 400 VIRGNA AVE S.W., WASHINGTON, D.C. 20024 (207) 564 2346
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With due regard for the cumulative effect of 2
these large conservatisas, concern was raised about a 3 near-term safety concern.
4 I will shortly discuss the efforts and 5 conclusions of the more recent industry work which.
8 confirms the large conservatisms in the earlier analyses 7 and indicates there is no significant near-term safety 8 concern.
I would first like to put in perspective the 9 issue we are discussing.
10 (Slide) 11 Hy second slide shows a typical reactor vessel 12 elevation of the veld locations indicated by the black 13 lines.
These velds can be viewed in another way in my 14 third slide.
15 (Slide) 18 This is a partial weld map of a typical 17 reactor vessel.
Envision, if you will, the reactor
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18 vessel being unfolded to form this map.
The complete 19 vessel consists of a large number of forgings and/or l
20 blades which are welded together.
The velds of interest 21 are those surrounding the core and typically represent 22 about 20 percent of the welds in a reactor vessel.
23 I call this to your attention simply to 24 illustrate the pressurited thermal shock issue, an issue 25 involving not caly a limited number of reactor vessels 9
ALDERSoN REPORTING. COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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but also a limited portion of these vessels.
What we 2
are therefore discussing is only the potential for a 3
througn-vall crack to be formed in a number of limited 4
locations and conservatively analyzed scenarios.
5 CONNISSIONER AHEARNE But you are not trying 6
to imply that there is no veld that might be at risk?
7 You still have to go through the analysis, do you not?
8 NR. GIBBSs Absolutely.
I am not trying to 9 imply that at all.
I as simply trying to limit the 10 scope of how much of these vessels is of concern.
I 11 CONNISSIONER AHEARNE:
The only problem is I 12 do not recall NRR as saying that every veld was a 13 concern.
So I think --
l 14 Mr. GIBBSs No, sir, I don't recall that 15 either.
19 CRAIRHAN PALLADIN0s Also there is an 17 implication in the way "only" is used, 'because I would 18 consider and I presume you would consider a through-wall 19 crack to be significant if it were not in one of these i
20 pla ce s.
21 HR. GIBBSs We would certainly consider it to 22 be significant, but we wan t to narrow the field of our l
23 scope of attention.
24 As I indicated earlier, work related to 25 ensuring reactor vessel integrity has been ongoing for 1
AI.DERSoN REPORTING COMPANY. INC.
400 VIRGINIA AVC. S.W., WASHINGTON. D.C. 20024 (202) 554-2346
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many years.
In order to obtain the materials data 2 necessary to establish operating limits and perform the 3 vessel integrity calculations, materials surveillance 4 programs are in place at operating plants.
'5 The output from these programs is used-to 6 establish limits for operation.
Concurrent with these 7 efforts, utilities and vwndors have been performing work l
8 related to the Heavy Section Steel Technology Program l
9 and performing calculations to benchmark fluence 10 analysis techniques.
11 In addition, many utilities have instituted 12 low-leakage fuel load designs which may reduce the 13 overall rate of vessel embrittlement from neutron 14 1rradiation.
15 CHAIRMAN PAL 1ADINOs Can you explore what you 16 sean by how many?
17 HR. GIBBSa The number is not immediately 18 available to me, Mr. Chairman.
I think it is in about l
19 the range of a dozen.
20 In the past calendar year, significant work 21 has been completed by the industry.
Small break 10CA 22 pressurized thermal shock analyses have been provided to 23 the staff.
Prelisinary mixing test data has been 24 developed under an EPHI program.
Procedures have been 25 and continue to be developed which upgrade the operator ALDER $oN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W. WASHINGTON, D.C. 20024 (20:D $54-234E
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guidance on how to effectively handle transients which 2 could cause overcooling.
3 Concurrently operator training in awareness of 4
thermal shock concerns has been improved and it is 5 continuing.
6 Eight utilities were required to develop and 7 submit 60-day and 150-day responses to the staff letter 8 of August 21, 1981 as supplemented in December.
The 9 analyses submitted by these utilities have shown that no to short-term concern for reactor vessel integrity exists
~
11 for their plants from overcooling transients and 12 accidents.
13 The most limiting plant demonstrated that many l
14 f ull power years are available bef ore the linear elastic 15 fracture mechanics acceptrnce criteria utilized is 16 reached.
These more favorable results as compared to 17 earlier bounding analyses were achieved in part by 18 including more plant-specific information.
19 It is expected that further plant-specific 20 analysis would show additional effective full power 21 years are still available.
22 As part of the NHC's evaluation of the three l
23 different PWB plant types, Duke Power has provided 1
24 technical information support to Oak Ridge in the 1
25 NRC-sponsored thermal shock evaluation of Oconee 1,
and ALDERSoN REPORTING COMPANY,INC.
400 VIRGINIA AVE, S W. WASHINGTON. D.C. 20024 (202) 554-2346
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this effort continues.
While not directly motivated by 2 pressurized thermal shock concerns, many hardware 3 changes have been or are being made which will reduce 4
transient severity and frequency but also improve 5 operator handling of plant transients by providing 6 additional and more reliable diagnostic instrumentation.
7 These changes include such things as feedvater system 8 upgrades and TSAT meters.
9 Another activity affecting an area of 10 co.gservatism is that of flaw characterization.
It 11 should be noted that NDE during vessel fabrication is 12 extensive.
In many. cases these examinations have been 13 supplemented by baseline inspections preparatory to 14 inservice inspection.
15 The recent results of substantial in-vessel 16 examinations of two units have indicated that there are 17 no inservice-induced flaws and tha t those indications 18 that were found were smaller than those assumed in the 19 fracture mechanics analyses.
20 CONHISSIONER AHEARNE:
Which units were those?
21 MB. GISBS4 The first two units at Oconee.
22 COMMISSIONER ROBERTS:
Can you describe the 23 methods of examinstion?
24 NR. GIBBS:
Ultrasonic examination.
Correct 25 me, Bob Gill, if I am wrong, but tha t particular ALDECN REPORTING COMPANY. INC.
400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554 2345
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examination was done completely in accordance with Reg 2
Guide 1.150, which is the most recent guidance on that 3
type of inspection.
4 CHAIRHAN PAL 1ADIN0s You say there were no 5
service-induced flaws and those indications that were 6
found are smaller than those assumed in the f racture 3
7 aechanics analyses.
Where did those flaws come from?
8 MR. GIBBS:
There were slag inclusions or some i
flaws that were in the plane of the metal of the vessel 10 that apparently were there at the time the material was 11 initially fabricated, but there were no cracks either in 12 the clad or in the base material directly underneath the 13 clad.
14 The vessel is totally free of any flaws in the 15 areas that vere examined.
16 CHAIRMAN PALIADINO:
Well, flaws and cracks
~
17 sometimes, depending on the nature of the flaws, 18 can't they?
But they are small.
19 HR. GIBBSs There are limits on flaw size that 20 are assumed in these analyses pertaining to the size and 21 orientation of the flaw, and there were none found, and 22 there were none found in the examination that would be 23 characterired or characteristic of any inservice 24 operation.
25 MR. TAY10R I think that is the important ALDERSoN REPORTING COMPANY. INC.
400 VIRGINIA AVE. S.W, WASHINGTON. 0.C. 20024 (202) 554-2345
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point, Mr. Chairman, that the indications that were 2 found were not of a kind that would indicate they were 3 induced by any operation.
There were some small i
4 indications but not the kind you would expect to come 5 from operation.
6 CONNISSIONER ROBERTS Is there any likelihood 7 in your ultrasonic examination you could pick up a 8 " defect" that had been in place since the vessel was 9 fabricated and make the wrong assumption -- do you to follow me?
11 HR. GIBBSa If the crack was oriented in a 12 radial direction, that had not been there at the time 13 the vessel was fabricated,. that would indicate it had 14 not a service-induced flaw.
15 COMMISSIONER ROBERTSs I understand.
16 MR. GIBB S s And there were none of those found.
17 COHNISSIONER ROBERS:
.Okay.
18 CHAIRMAN PALLADINO:
But you did compare, I i
19 gather, when you compared the examinations you made on 20 the vessel after operation with the map you had before 21 on operation?
22 MR. GIBBS:
Bob Gill, could you respond to 23 tha t question?
24 HR. GILL:
This is Bob Gill from Duke Power.
25 We went back to the original archives and we AI.DERSoN REPORTING COMPANY. INC.
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tried to make some comparison between those indications 2
that were found, and they were basically planar-type 3
indications, two-dimensional, due to the rolling of the 4
plates into the geometry necessary for the vessel.
They 5
were not service-induced cracks.
This was all evaluated 6 by appropriate quality assurance specialicts.
7 We did prepare a report and provided this 8
information to the staff last December as part of the 9
ten-year ISI program.
So we didn't directly compare all to the indications we found to the original examination, 11 but some places they did show up, yes.
12 CHAIRMAN PALLADINO:
I just was curious as to 13 how you determined there were no service-induced flaws 14 if you didn't make the comparison.
15 MR. GILL:
It is basically the characteristic 16 of the reflecting signal that comes back from the l
17 indication as to whether it is a crack-type indication 18 or a planar or laminar.
19 CHAIRMAN PALLADINO:
Is that so clear that --
20 dR. GILLS These are Class III OA-type 21 evaluators.
It is clear, yes, sir.
And none of those 22 were reportable by the ASME code requirements. They were 23 all much smaller.
24 CHAIRMAN PALLADINO:
Thank you.
Go on.
25 COMMISSIONER AHEARNE:
Could I ask?
ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554 2345
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CHAIBNAN PALLADINO:
Go ahead.
2 COHNISSIONER AHEARNE:
It sounds basically 3
like what you are saying is the reason you are 4 concluding they were not due to service-related stress 5
is because of the character.
6 HR. GILL:
That is correct.
7 COHNISSIONER AHEABNE:
Rather than that the 8
archival records are sufficiently clear, is that correct?
9 HR. GILL:
The evaluators determined the type 10 of flaw, whether it be a plane or a crack, and they were 11 able to determine there was some slag inclusion, but 12 that is not a structural-type situation.
13 CHAIRMAN PALLADINO:
I could understand those 14 slag inclusions if.you can identify them clearly.
16 HR. GILL:
My examination is that these planar 16 flaws were right at the edge of the base metal and 17 indicated where the roller might have done an uneven 18 role on tha t particular point.
Unit 1 has plates and 19 Unit 2 has forgings, so there were none of those 20 involved.
So a forging-type assembly gives you even 21 less information.
There were no service-induced fla ws 22 there.
23 CHAIRHAN PALLADINO:
All right, thank you.
24 HR. GIBBS:
The message I wish to convey to 25 you is that the industry involvement with matters l
ALDERSoN REPORTING COMPANY. INC.
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related to reactor vessel integrity has been 2
substantial.
During 1982 and succeeding years, industry 3
vill continue to pursue actions that will aid in the 4 orderly resolution of the pressurized thermal shock 5
issue.
6 Some of these actions will aid in better 7 understanding analytical techniques that have been used 8
in the recent evaluation of pressurized thermal shock.
9 Some will lead to a better understanding of realistic 10 plant transient behavior and operator response.
We 11 believe these actions will maintain orderly progress 12 toward the final resolution of this issue.
13 Industry is sponsoring a nusber of programs 14 aimed at confirming the conservatisms in the assumptions 15 used in the recent evaluations in providing insight.into 16 many of the technical details of the pressurized thermal 17 shock issue.
18 Following my discussion, respresentatives of 19 EPHI will describe some of these programs.
20 (Slide) l 21 In recent years there has been considerable 22 emphasis on how the operator responds to plant l
23 occurrences.
Work is continuing on plant-specific 1
24 procedure revisions, operator training and functional 25 response or symptom-oriented operating guidelines.
This ALDERSoN REPCRTING COMPANY. INC.
._ _400 VIRGINIA AVE., S.W WASHINGTON. 0.C. 20024 (202) 554-2346
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f unctional symptom-oriented approach simplifies the 2 operator's task in a multiple failure scenario by 3
focusing his attention on several key safety 4 parameters.
This approach is not event specific.
5 (Slide) 6 Now, at this point in view of the discussions 7 with respect to the interface with the operator that 8 occurred this morning I felt it would be worthwhile to 9 depart from the script and introduce another concept to 10 you.
What I have on the screen is a curve that goes by 11 a variety of different names.
I have always referred to 12 it as the operator's curve, and it is a simplified 13 version of an operator's curve.
14 This one was furnished by Combustion 15 Engineering, and it defines an allowable operating i
16 region with respect to temperature and pressure which is 17 acceptable for opera tions by the plant operator.
If the 18 operator departs from -- I guess I should add also at 19 this point that I believe I can start with a fairly high 20 level of confidence that every pressurized water reactor 21 in the country has such an operator's curve available to 22 them, many of them prominently displayed in the control 23 room.
l 24 Now, if the operator gets outside of the l
25 region defined by this acceptable operating region, he ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE. S.W., WASHINGTON, O.C. 20024 (202) 554 2345
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is getting into trouble.
We had an example of an 2 operator proceeding to the right of the right-hand curve 3
a few years ago in Harrisburg, which led to difficulties 4
for the operator.
5 What we are talking about here in this.
8 pressurized thermal shock issue would be departures to 7
the lef t of the lef t-hand curve.
Now, that left-hand 8 curve is typically derived on the basis of the brittle 9 fracture state of the reactor vessel, its irradiation, to the extent to which it has been irradiated.
11 CHAIRMAN PAllADINO:
When you talk about the 12 left-hand curve, are you talking about --
13 HR. GIBBS:
Yes, sir, the one that defines the 14 left-hand boundary of the acceptable operating region.
15 Now, that lef t-hand curve is derived f rom the state of 18 irradiation of the reactor, and it is also derived f rom 17 the assumptions that are made in the maximum allowable 18 cooldown rate to which the vessel is designed.
- Clearly, 19 as the vessel becomes more irradiated, that curve can 20 shift to th e righ t, or alternatively, if one selects a 21 transient which would lead to a cooldown rate greater 22 than 100 degrees per hour as the design basis event, 23 that may shift the curve to the right.
24 In any event, as long the operator stays 25 within that acceptable operating region, he is all right 44.CER$oN REPORTING COMPANY. INC.
400 VIRGINm AVE., S.W., WASHINGTON O.C. 20024 (202) 554 2345
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insof ar as either having boiling in the core, which 2
would occur if he shif ts to the right,.or insof ar as 3 having problems with this pressurized thermal shock 4 issue should he proceed to the left.
5 Now, the operator is basically performing his 6 task driven by parameters, the parameters of pressure 7 and temperature.
He has availale to his numerous 8 equipment to control pressure and temperature.
He has 9 spray valves, heaters, PORVs, he has HPCI that he may or 10 may not throttle, and a rhole host of other various 11 equipment.
His task is to remain inside that 12 cross-hatched region.
13 Now, that region -- an operator has to 14 consider that as being inviolate, regardless of whether 15 he is dealing with normal operation or a transient.
16 Should he be confronted with a transient such as that 17 that occurred at Ginna, he is obligated to sti11' remain 18 within that region, and that is an assumption that we 19 have to impose upon him,'that the operator will in fact 20 continue to operate in that region.
21 22 23 24 25 ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W. WASHINGTON D.C. 20024 (202) 554-2346
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Well, my reaction to the discussion I heard 2
this morning indicated to me that perhaps if you were 3
made aware of this curve, which is one of the first 4
chapters of the bible for a plant operator, that it 5
might answer a lot of your questions in this area.
8 CHAIRHAN PALLADINO:
I was going to ask a good 7 question.
We may have the same question.
First, is 8 there a different c_urve for a different age?
9 HR. GIBBS:
Yes, sir.
10 CHAIRNAN PALLADINO:
How often does it change?
11 HR. GIBBSs As the plant experiences increased 12 embrittle' ent to the reactor vessel, that lefthand curve 13 has to change.
The frequency by which it changes is 14 largely a function of what the operator selects to do.
15 He can move the thing in ten-year increments or'two-year 18 increments or whatever increment he feels is necessary 17 or appropriate.
18 COMMISSIONER AHEARNE:
What is the industry 19 practice?
20 MR. GIBBS I think the longer interval is 21 more common than the shorter.
I don 't know precisely 22 what the normal practice is.
Jim, can you --
I MR. TAYLOR:
No, I don't.
l 23 CHAIRMAN PALLADINO:
How large does that range 24 25 get late in life?
It looks reasonably broad here.
ALDER $oN REPORTING COMPANY,INC.
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1 MR. GIBBSs It. would depend upon the 2
particulars.
It would depend upon the fluence that the 3 particular vessel was exposed to and the copper content 4 in the wells and the plate material.
5 CHAIRMAN PALLADIN0s Do you have examples of 6
this curve for, le t's say, late in life?
7 NB. GIBBSs This one here is a representative 8 curve.
Pat, why don't you put on the Oconee curve?
9 (Slide.)
to MS. GIBBSs This is an actual curve for Oconee 11 2 Cycle 5.
12 CHAIRMAN PALLADIN0s Which is the 13 cross-h a tched ?
14 HR. GIBBS:
That would be the region between 15 Curve 1 and Curve 2.
16 CHAIRMAN PALLADINO I can't tell which is 17 which.
18 MH. GIBBS, "he one furthest left is Curve 1,
19 and Curve 2 actually i t the curve which is defined by the fuel, the partici.c f uel which is used in this 20 21 reactor.
CHAIRMAN PALLADIN0s Is it the intermediate 22 23 one?
MR. GIBBS:
It is the one that goes in stacks, 24 25 the one tha t is labeled 50 degrees subcooline.
If the ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVEL. S.W., WASHINGTCN, D.C. 20024 (202) 554 2345
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fuel were not concerned and you were only concerned 2
about 50 degrees subcooling on the righthand side and 3
embrittlement on the lefthand side, then it would be the 4
region between those two curves.
As you can see, this 5
particular curve has a dotted line in it which defines 6 the minimum condition for operating the reactor coolant 1
7 pumps, so these curves can become more complicated for a 8 particular plant specific application, but the end 9
result is that there is defined somewhere between this 10 family of curves an allowable operating region.
11 CHAIBMAN PAL 1ADINO:
Now, there is another 12 question that comes up --this is fine.
This is like 13 having the lanes in a road marked.
And that is 14 helpful.
But there is a new driver who has the problem 15 of how do I stay within those lines, and this is more 16 complicated, because in addition to a steering wheel and l
17 speed there are other things that one could-be doing.
18 So, while this is helpful, does it really address, for 19 example, the concern raised earlier this morning that 20 rou have so many options on what you have to do, you 21 might take an option that gets you on the wrong side, 22 and even though you know it is wrong, you are there.
3R. GIBBS:
Well, if a person is approaching 23 24 Curve 1, he has pretty clear evidence that his pressure 25 is too high and he has to do something about his ALDER'. JN REPORTING COMPANY. INC.
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pressure, or he has to get his temperature down.
i i
2 CHAIRMAN PALLADINO:
Well, you are assuming 3
things will happen slowly and he doesn't have to make 4 fast decisions.
5 MR. GIBBS:
Even.if things are happening 6 rapidly and he is approaching Curve 1, he has to get his 7 pressure down, Curve 1 being the brittle failure curve.
8 Now, he has a number of ways he can do that.
He can 9 spray the pressu::izer.
He can throttle HPCI if HPCI is to on.
He can vent th rough the PORY.
And the specific 11 choice that he selects is largely going to be a function 12 of his procedures and his judgment.
13 COMMISSIONER AHEARNE '
I don't think, Clark, 14 ve are really questioning the absence of such a region 15 in which he has to star.
We are more asking the 16 question of how confident are we that the procedures are
~
17 in place that will direct him to' stay within this and i
18 how likely is it that a set of circumstances will arise 1
19 that it gets difficult for him to decide which sets of 20 procedures ought he to be following.
That is really 21 more the question.
MB. GIBBS I think that is a very reasonable 22 23 question that should occur to all of us.
I guess what I 24 an attem pting to establish here is a basis upon which we 25 can assume that there is a reasonable assumption that we ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASMNGToN, D.C. 20024 (202) 554-2345
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can have reasonable confidence that the operator can in 2
f act control these transients and stay within some kind 3
of an acceptable operatino region.
The guidance is 4
simple, and it is parameter-dependent as opposed to 5
equipment-dependent.
6 CHAIRMAN PALLADINO:
Well, let's assume he is 7
approaching the pressure, and you say he wants to bring 8
the pressure down, and if you were assuming you were 9
coming straight down, then he gets out of trouble, but 10 in the process of bringing the pressure down he may go 11 to the left and bring the temperature down, depending on 12 what means he uses, and how confident are we that the 13 procedures are clear enough that that is what you need 14 to do, that yo u sho uld n ' t take tha t step, that you 15 should take some other step?
18 HR. GIBBS4 I think insof ar as your question 17 is directed at should we more closely examine our 18 procedures to ensure that they are in conformance with 19 this sort of guidance, I would wholeheartedly agree with i
20 that.
There is a need for that.
21 CHAIRMAN PAllADINO:
Okay.
Go ahead.
22 MB. GIBBS:
But clearly the operator, if he 23 wishes to reduce pressure without impacting temperature, 24 or while having modest impact on temperature, he has a 25 number of options for doing that.
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1 CHAIRHAN PAllADIN0s One of the points that 2 was made this morning was that he has competing 3 options.
One thing that would say he ought to be doing 4
this for one reason and he ought to be doing something 5
else for another.
Can you write procedures so clearly 6
that on review later you can say, boy, that was just the 7
right thing to have done?
8 HR. GIBBS:
I think that you can.
Pat, why 9 don't you go back to the CE slide a second?
I think 10 there are opportunities for doing that.
I am not sure 11 that we have developed the best approach for doing that 12 Yet.
13 (Slide.)
14 MR. GIBBSa But if you look at this particular 15 slide, here is one where combustion is laid on a to 200-degree subcooling line.
Unfortunately, that line is 17 outside the acceptable operating region.
If that laid 18 on a 150-degree subcooling line, it may be fully 19 acceptable within the operating region.
Now, the 20 operator has at his disposal a margin of, saturation 21 meter.
If his instructions are 'very simply to maintain 22 his margin of saturation between 1500 and 50 degrees, by the various devices that are at his disposal for doing 23 24 that, and his procedures indicate what those devices 25 are, it would seem to me that here is an opportunity for ALDER $oN REPORTING COMPANY,INC,
26 l
1 very clear and simple guidance that can be provided to 2.the operator to ensure that such competitive events as 3
you have described can be adequately addressed by the 4
operator.
5 COHNISSIONER AREARNE:
And as long as all the 6
possible scenarios that come up are ones in which there 7
are no two solutions which lead to different procedures 8
being followed, you are right.
And I guess part of the 9
concern that at least I know I have is to make sure that to the sta ff has anci1 ~ ed the material provided so that we i
all can have confidence that those procedures are such.
11 l
12 If it ends up that the operator has to have your 13 understanding of the operation of his reactor, then I 14 would be a let less comfortable than if it ends up with 15 rea'so nable type training that operators get.
16 HR. GIBBS:
I would hope, sir, that he has a 17 great deal more than mine.
18 (General laughter.)
1 19 CONHISSIONER AHEARNE:
I am not sure which way 20 to interpret that.
Clark, are you really saying that 21 You hope all of your operators have a greater deal of 22 understanding of the reactor behavior than you do?
23 NE. GIBBS:
I certainly don't think that it 24 transcends good judgment to assume that the operator 25 understands his operator's curve, understands the ALDERSoN REPoRDNG COMPANY,INC, 400 VIRGINIA AVE., S.W WASHINGTON. D.C. 20024 (202) 554-2345
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importance of it, understands his obligations to remain 2
within the cross-hatched region of that operator's 3
curve, and is aware of the various mechanisms that he 4
has at his disposal to move him along that curve, and in 5
what general direction he vill move when he exercises 6 one of those mechanisms.
7 COHNISSIONER AHEARNE:
Sure, but you weren't 8 -- or were you by that last remark saying you hope that 9
your operator has a greater understanding of a reactor 10 than you do?
11 MB. GIBBS:
Well, sir, I meant to imply that 12 he has a greater understanding of the operation of a 13 reactor.
The last time I operated a reactor was about 14 ten years ago or more.
These people do it every day, G
15 and the operator's curve is something that is very 16 important to these operators.
17 CHAIRMAN PALLADINO:
Why don'E we let you go 18 on?
I want to come back to this.
19 HR. GIBBSs One of the long-term activities I l
l 20 mentioned earlier involves the material surveillance 1
21 program whose objective is to provide early indication 22 of the changes in vessel properties due to irradiation.
23 These programs are extensive and will continue for many 24 years in the future.
As part of the material 25 surveillance program, evaluations et dosimeters removed ALDERSoN REPoF; TING COMPANY, INC, 400 ARGIMA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554 2346
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from reactor vessel surveillance capsules are also 2
performed.
These efforts will f urther enhance the 3
predictive capability with regard to future reactor 4 vessel material properties.
5 (Commissioner Gilinsky joined the meeting at 6 3:03 o' clock p.m.;
7 MR. GIBBS:
Current analysis use 8 conservatively assumed flav sizes, loca tions, and 9 orientations.
Efforts are under way to more accurately to characterize actual flaws in reactor vessels as 11 determined by in-service inspections.
The shapes and 12 sizes of actual flaws are being compared to those 13 assumed in fracture mechanics analyses.
Industry 14 believes this can be of significant value in quantifying 15 the actual conservatisms in this area.
16 Recently, the newly formed AIF reactor vessel 17 integrity subcommittee has also recommended to member-18 utilities that they consider performing enhanced 39 examinations in any upcoming in-service inspections.
An 20 important aspect of this issue is ensuring that plant 21 operators have an understanding of the events that occur 22 at operating plants and the potential consequences of 23 such events.
INPO has established a program for reviev 24 of plant operating experience, including potential 25 overcooling events, and uses its expertise to advise ALDERSoN REPORTING COMPANY. INC.
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utilities of occurrences that are of significance.
2 Utilities and vendors closely monitor the work 3 done by INPO and f actor its results into their 4
procedures and training programs.
Recent responses to 5
the NRC 150-day letters demonstrated that there is no e short-term safety concern.
7 (Commissioner Bradford left the meeting at 8
3:05 p.m.)
9 HR. GIBBS:
This suggests that a continued to orderly approach to complete closure of this issue vill 11 best serve industry and the NBC.
To minimize 12 unnecessary work and efficiently utilize available 13 resources, industry and the NRC should jointly determine 14 the priority and scope of any additional ef fort needed.
15 Our subcommittee on reactor vessel integrity will be 16 pleased to work with the NRC in this matter.
17 I might add here parenthetically we also would 18 be pleased to work with the NRC in assisting them in 19 their consideration of any additional corrective actions 20 that may be required to close this issue.
21 Before concluding my remarks, I want to be 22 sure I have left the correct impression with regard to 23 future work.
While we are convinced that there is no i
24 near-term safety concern, we are not stopping work.
25 Should any of the ongoing work indicate that full design ALDERSON REPORTING COMPANY. INC.
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vessel lifetime cannot be achieved, other actions, 2 probably plant-specific, can be taken.
These involved 3 modified fuel management schemes, analysis and testing, 4 modifications of operating limits, hardware changes, and 5 lastly, although we don't anticipate needing it, in 6 place vessel annealing.
7 In addition, further procedural modifications 8 and training will provide added confidence that credible 9 pressurized thermal shock scenarios cannot challenge to reactor vessel integrity.
11 (Slide.)
12 ER. GIBBS:
I will use my last slide to 13 summarize.
Industry truly does appreciate and 14 understand the significance of the pressurized thermal 15 shock issue.
16 CHAIRMAN PALLADIN04 Do you have another 17 copy?
Eine has two of the same slide.
18 All right.
Go ahead.
19 MR. GISBS:
It is not a new issue, but it is a i
20 new twist on the issue which has been given auch i
21 attention'over tha years.
Furthermore, it is a l
22 significant issue only on a limited number of vessels.
23 Industry resources applied to pressurized thermal shock 24 or other related matters in the past year hava been 25 significant.
A portion of these resources have been ALDERSoN REPORTING COMPANY. INC.
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directly related to responding to a host of requests for 2 information f rom the NBC staff on this issue.
3 As a result of this work, it has been 4 concluded that there is no near-term safety concern.
5 However, work is continuing in many areas.
We vill hear 6 about many of these in a minute.
We believe these 7 efforts will confirm the validity of the conclusions 8 reached in the work that has been completed.
g At this time, we believe that some further 10 confirmatory analyses, training, and procedural changes 11 are required.
Obviously, we fully intend to continue 12 vork in these areas as well as with established material 13 surveillance programs which provide good early 14 indication of actual materials properties changes.
We 15 feel strongly that much can be gained by having free and 16 open communications with the staff in regard to future 17 work.
In such a complex issue as this, many resources 18 can be inefficiently employed unless all actions are 19 carefully planned.
20 We want to work with the staff to minimize the 21 total effort required and to assure that those man-hours 22 that are spent yield meaningful und significant 23 results.
We do not want to expand unjustified resources-24 on this issue, and in the process divert attention f rom 25 other more important matters.
l ALDERSoN REPORTING-COMPANY,INC, 400 VIRGINIA AVE S.W., WASHINGTON, D.C. 20024 (202) 554-2346
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1 That concludes my comments on this subject.
2 CHAIBMAN PALLADIN04 One question.
I guess it 3
is in part remaining from this morning's discussion, 4
that in making a statement such as you did on Page 6 and 5
Page 10, as I recall, at least in responses to the 6
150-day letters demonstrated that there was no 7 short-term safety concern, and I am not saying there is, 8 but somewhere along the line the assumptions made in the 9 analysis come into play, and I am still concerned that to operators have to make decisions in a short period of 11 time on what they think has transpired at that time.
12 And this morning several Commissioners 13 addressed the fact that if an assumption on a number of 14 these analyses was that the reactor coolant pumps would 15 trip in 30 seconds, and I was told that is the 16 conservative assumption, then af terwards in 17 conversations with other technical people they say that 18 is not necessarily the conservative assumption, that l
19 sometimes tripping is not the right thing to do, or it' i
20 depends on which way you do it.
21 And I guess I ar. concerned, do we know enough gg so that we can get agreement on what these concervative 23 steps are for the operator to take.
If we seem to have 1
24 this much lack of clarity on a point such as that, I 25 vonder whether we have gone far enough in examining the i
t
(
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assumptions that are implied in making a statement such 2 as you made on Page 10.
3 HR. GIBBS:
I think with respect to the 4 reactor coolant pump subject, I think the way you deal 5 with that' matter is you an.alyze for both cases, since 6 there is the high probability you may leave them on or 7 turn them off.
You have to look at the probability of 8 both examples, and I believe that in fact is what was e performed, at least by some of the vendors.
10 Now, with respect to other operator actions, 11 typically operator intervention into these transients 12 would be acsumed to occur at periods of time which are 13 'such greater than 30 seconds.
14 CHAIEHAN PAL 1ADIN0s Well, if someone has to 15 decide in 30 seconds whether to trip or not to trip the 16 pump, that means he has to know pretty much about where 17 the accident is going.
Tripping the pump leads 'to one 18 circumstance, and not tripping the pump could also give tg you a problem with regard to thermal shock, and I guess 20 I would like to achieve a level of confidence such that 21 I say, you are really sure that this statement could be 22 made with a high degree of confidence.
23 MR. GIBBS4 Well, I guess the degree of confidence would be enhanced if everybody did analysis 24 25 for both cases, and I cannot assert with confidence tha t ALDEASoN REPORTING COMPANY, INC, 400 Vl4GINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) $54 2345
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that was done.
Jim?
2 HR. TAYLOR:
I was not going to talk about the 3
reactor coolant puno on versus off issue, but I was 4
going to talk about --
5 CHAIRHAN PALLADINO You would rather have me e
use it as an example.
7 MR. TAYLOR But !. think the main thrust of a
your concern, and it is a legitimate one, is what kind 9
of confidence do we have that the operator will do what 10 he is instructed to do.
11 CHAIRHAN PALLADINO:
Or that we can write 12 procedures to tell him what he ought to do.
13 MR. TAILOR:
And I think the effort that has 14 been ongoing for approximately two years now, in which 15 all of the vendors and many of the utilities -- almost 16 all of the utilities involving symptom-oriented 17 procedures is -- it has that at. the heart of it.
It is 18 to try to divorce the operator's actions from the need 19 to diagnose what is really hap 9ening, but to locate the 20 parameters and from those key parameters he then is able 21 to more simply judge what direction to go.
22 So, this is all aimed, and the staff has these 23 things under review righ t now, these matters under 24 review, but the whole thrust of the sympton-oriented 25 approach is to make his diagnosis quicker and more ALDERSoN REr'ORTING COMPANY,INC, 400 VIRGINIA AVE S.W., WASHINGTCN. 0.C. 20024 (202) 554-2345
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reliable on these kinds of transients.
2 CHAIRMAN PALlADINO:
Even though the staff has 3
it under review, I presume you are satisfied that when 4
they make their review they are going to confirm that 5
there are no major choices that remain by the operator 6
during an event.
7 MR. TAY10R4 He have done extensive reviews.
8 I just merely meant to convey the status of the issues e in terms of saying the staff had. hem under review, but to the whole approach to sympton-oriented procedures is one 11 which has been very carefully thought through.
It has 12 involved such things as walkthroughs through the 13 plants.
It involves the operating personnel 14 themselves, And so that is not to say that there are 15 not going to be shortcomings in there, but they are a to far superior way to dealing with the possibility of 17 operator confusion compared to event-oriented procedures.
18 COMMISSIONER AHEARNE:
Clark, I gather that 19 AIF's position is that first there is no near-term 20 involvement, and second, with regard to the long-term 21 problem, the continuation of the research work, further 22 work, but that at the moment you believe the potential l
23 scenarios are sufficiently understood at least in the l
24 sense of bounding the symptoms that might show up that 25 you can write adequate procedures for the operator to ALDERSoN REPORTING-COMPANY,INC.
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2 36 I
make sure that these scenarios are uncovered, and then I 2
am not sure, but is it also AIT's belief that those 3
procedures are in fact either already written or in the 4
process of being written?
Is that a fair statement?
5 MR. GIBBS:
I would not disagree with anything 6
you said up until the last.
I cannot confirm that.
The 7
extent to which the procedures have been prepared with 8
this particular issue in mind and motivated by this 9
particular issue I believe probably would be an 10 approprite topic for review.
I would not be totally 11 confident at this point in time that those procedures 12 are inviolate with respect to this issue.
13 CHAIRMAN PALLADINos Any other questions?
14 CONMISSIONER GILINSKYa Yes.
Could you say 15 something about how you view the cost of what you call l
is modified fuel management schemes, which I take it are
~
17' schemes to reduce t!e flux?
18 3R. GIBBS:
The modified management schemes 19 that have been addressed in this paper are schemes which 20 incorporate 18-month cycles, and it happens that when 21 one modifies his fuel management scheme from a 12-month 22 to an 18-month cycle, his vessel fluence drops by 25 to 23 35 percent, in that range.
It is a fortuitous cutcome I
of a modification which is activated by something else.
24 25 COMMISSIONER AHEARNE That something else ALDER $oN REPORTING COMPANY. INC.
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being?
2 MB. GIBBS:. Improved economics and plant 3 a vailabilit y.
4 COMMISSIONER GILINSKY:
So you are not talking 5 about things like putting in dummy elements around the 6 outside?
7 NB. GIBBS:
No, sir.
8 CONNISSIONER GIIINSKY:
You don't think you 9
vill go into anything like that?
10 MB. GIBBS:
Well, I would be a little bit 11 reluctant to judge the future on matters such as that.
12 It certainly depends upon what forces are at work, 13 whether the plant would require being downgraded, what 14 the other options are, and how the economics pan out.
15 CONNISSIONER GILINSKY Because you do talk 16 about in place vessel annealing, which seems to be a 17 more drastic thing'to be doing.
I will tell you 18 f ra nkly, I am a little surprised tha t the owners of 19 these plants haven't moved toward one or another of 20 these schemes that would slow down the flux on the 21 vessel.
You know, quite apart from any safety issues, 22 just to protect the investment, so to speak.
23 MR. GIBBSs As an owner of these plants, I 24 presume the designer has designed the plant to 25 accommodate the fluence it is going to be exposed to ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE S.W., WASHINGTON, D.C. 20024 (202) 554 2345
38 1
over its lifetime.
2 COMMISSIONER GILINSKYa Well, there is some 3 uncertainty about that.
4 MR. GIBBS There in.
5 COMMISSIONER GILINSKY:
Suppose we grant and 6 just accept what you say about the near-term safety 7
problem.
I would think that one would want to play it 8
safe initially by slowing down the aging of the vessel e
to be sure that 10 HR. GIBBS:
That has been suggested, but I 11 think we have to have more information before we can 12 make a decision like that.
13 CRAIRMAN PALLADIN04 Well, let me ask you, on 14 Page 5 it says, in addition, many utilities have 15 instituted low leakage fuel load designs which may 16 reduce the overall rate of vessel imbrittlement from 17 neutron irradiation.
That is not what -- you were not 18 talking about t
19 HR. GIBBS:
I was not talking about designs 20 that incorporate a row of shield assemblies.
21 CHAIRMAN PALLADINO:
Or depleted fuel elements.
22 MR. GIBBSt I was talking about designs tha t 23 were put in their to achieve 18-month cycles.
24 CHAIRMAN PALLADINO:
I see.
So then many 25 utilities have not done what I thought you were l
ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVL S.W., WASHINGTON. O C. 20024 (202) 554-2346
39 1
implying, and that was to put low leakage --
2 HR. GIBBS:
I know of no domestic utilities 3
that have done that.
4 CHAIREAN PALLADINO:
So this is the 18-month 5
fuel cycle.
6 CONNISSIONER GILINSKY When you talk of 7 hardware changes, what is it that you have in mind?
8 HR. GIBBSa Well, for example, such things as 9 taking the auxiliary feedwater off the ICS, most of 10 which was in response to THI, but does have implications 11 with respect to this issue.
12 13 14 15 16 17 18 l
19 20 21 22 23 24 25 ALDERSoN REPORTING COMPANY,INC.
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One plant has to increase the temperature of 2 their makeup wate.r to their ECCS, for example, I think 3 to 130 degrees.
4 CHAIRHAN PALLADINO:
Did you say what 5 company?
6 HR. GIBBS:
Yankee Rove.
About 130 as I 7 recall, yes, sir.
8 COHNISSIONER GILINSKYs Perhaps I didn't 9 understand your answer.
But then did you deliberately to leave out options like putting in dummy elements or 11 depleted elements around the outside?
12 HR. GIBBS:
Commissioner Gilinsky, we are not 13 deliberately excluding that, but we don't want to make 14 that decision until we know more about it.
We would 15 like to know how much it costs, does it involve a plant 16 downgrade, if it does what's the economics associated 37 with that and what are the options, and is it l
18 necessary.
I COMMISSIONER GILINSKY:
But this is just a ig l
to list of items that you think ought to be considered, as
(
21 I take it, and you left that one off.
And that's what l
22 I'm asking.
You do include something which goes 23 further, which is in-plant vessel annealing.
24 MR. GIBBSs Which page are you reading from?
25 COHNISSIONER GILINSK!
Page 10.
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M8. GIBBS:
I don't think that last was meant 2
to be inclusive, but modified fuel management schemes 3
would include that as a subset.
4 COMMISSIONER GILINSKYa That's what I was 5 asking you when you said you didn't have that in mind.
6 HR. GIBBS:
I thought you were referring to 7
the statement that was made back here earlier on page 5, 8 where I talk about what has already been done, and what 9 has been done does not include that sort of things.
10 COMBISSIONER GILINSKYs No, I was just looking 11 at your list of things to be looked at.
12 MR. GIBBSs Without question, that's an option 13 and it should be evaluated.
But if it involves a 14 significant plant downgrade that's going to penalize 15 that option.
16 COMMISSIONER GILINSKY That's what I was 17 asking you.
Do you have any sense for what sort of 1
18 penalty is involved there?
19 MR. GIBBS:
No, sir.
But if you have got a 20 177 fuel assembly core and you take out 37 of your 21 assemblies and replace them with something that doesn't 22 do anything for you, I would expect it would be quite a 23 bit.
l COMMISSIONER GILINSKYs Do you know what was 24 25 done in Europe ?
l 1
l ALDER $oN REPORTING COMPANY,INC, 400 VIRGINtA AVE., S.W. WASHINGTON, D.C. 20024 (202) 564 2345
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1 MR. GIBBS:
I heard the testimony by the staff 2
this morning.
3 COMMISSIONER GILINSKYa You're not otherwise 4 familiar with it?
5 MR. GIBBS:
No, sir'.
Perhaps my colleagues 6 f rom EPRI can shed some additional light on that 7 subject.
8 COMMISSIONER GILINSKY Thank you.
9 CHAIRMAN PALLADIN0s Mr. Taylor, did you have 10 a presentation?
11 MR. TAYLOR:
No.
CHAIRMAN' PALLA'DINos Well, unless there are 12 13 more questions, at this time --
14 COMMISSIONER ROBERTS:
I do have a question.
15 Refresh my memory.
I haven't been involved in env 16 ultrasonic tests in a long time.
Tha t's a direct 17 reading indication.
The operator interprets the 18 response of the instrument on the spot, is that 19 correct?
20
-dR. GIBBS:
I believe he has a graph that he 21 looks at.
In that sense it's direct reading.
Bob Gill, 22 could you expand on that a little bit?
MR. GILLa I'm not an expert on ultrasonic 23 24 testing.
CHAIRMAN PALLADIN04 Would you identify 25 ALDERSoN REPORTING COMPANY,INC, 400 \\1RGINLA AVE., S.W WASHINGTCN, D.C. 20024 (202) 554 2345
43 1
yourself?
2 ER. GILL:
I'm Bob Gill.
3 They have a fan that sits in the containment 4
and as the ultrasonic transducer goes around on the veld 5
there is an operator-examiner sitting there watching the 8 signal as it ccees out.
In fact, the one that we used 7 had four different transducers, one set at zero angle, 8
and one about--
9 COMMISSIONER ROBERTS:
I saw you do it.
10 MR. GILLt They directly read it as they are 11 moving past the velds.
12 COMMISSIONER ROBERTS:
But as I recall, there 13 is no permanent record of that.
The operatog makes the 14 interpretation of the reading.
Okay.
15 COMMISSIONER AHEARNE4 If there is no 18 permanent record, how have you then gone back and 17 checked the records in the archives?
18 MR. GILL:
The archives were done by other 19 means, such as radiographic type of sensing.
20 COMMISSIONER AHEARNE:
Yes, but what are you 21 checking again st?
22 ER. GILL:
Well, you do record these as the 23 var they are.
The charts sets -- there is a hard copy.
24 It may not be a copy of the signal, but it's a copy of 25 the indication on a particular veld, of the actual l
1 1
l AI.0ER$CN REPORTING COMPANY. INC.
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location.
2 COHNISSIONER AHEARNE:
You mean the 3
interpre*ntion that the particular instrument operator 4
makes, is that what you record?
5 HR. GILLS That's correct.
He says, I see an 8 indication at this location, he writes down what it is 7 and then evaluates it and determines if it's within the 8 code or not within the code, and goes further if 9
necessary.
10 CHAIRMAN PALLADINO:
Okay.
Are you gentlemen 11 going to be --
12 HR. GIBBS:
Yes, sir, I'd like to turn over 13 the floor to my colleagues from EPHI, and Warren Owen 14 will be leading off that group.
15 CHAIRMAN PALLADINO:
T. hank you.
And if we 18 have more questions you will be here for response.
Is 17 that right?
18 HR. GIBBSa Yes, sir.
l l
39 CHAIRHAN PALLADINO:
i 20 Warren, are you going to lead off?
Will you 21 introduce your colleagues?
22 HR. OWENs Yes.
23 CHAIRMAN PALLADINO:
Would you like to 24 proceed?
l 25 HR. OWEN:
My name is Warren Owen, senior vice l
l
(
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1 president of Duke Power Company.
But I'm here this 2
afternoon as a member of the Electric Power Research 3
Institute Connittee, which was given oversight and 4.
policy responsibility for the activities of the nuclear 5
safety analysis center when it was formed some three 6 years ago.
It's an advisory structure.
The U.S.
7 utilities have selected those areas of research in which 8
their funds are to be invested by EPHI.
9 Over the past eight years the utility advisory 10 structure has put a high priority on research work in 11 the nuclear power division of EPRI, focusing on 12 important safety concerns, such as reactor vessel 13 integrity.
T'ais research has included extensive studies 14 of the effects of fast neutron exposure on reactor 15 vessel steels and other structural mechanics and stress to distributions related to reactor vessels with a variety 17 6f hypothetical flaws.
18 EPRI has also supported research on basic 19 fracture mechanics, neutron exposure, and 20 non-destructive examination, to wit, the NDT center, 21 with primary coolant and systen behavior which could 22 introduce thermal transients that would result in stress 23 changes in pressure vessel valls.
24 The current interest in pressurized vessel shock has resulted in the need to call upon the research 25 ALDERSoN REPORTING COMPANY,INC,
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results fros :11 of these programs.
At EPRI, the 2
nuclear safety analysis center and other departments of 3
the nuclear power division work together in an 4 integrated fashion to make the best possible use of the
,5 research basis that has been developed over the past 6 eight years.
7 The thermal shock issue is receiving serious 8 attention by the industry and as well at EPHI, and we 9
believe that the research base will help provide a fira 10 technical foundation on which regulatory decisions can 11 be made.
You know, one is never eager to see events 12 occur which lead to the identification of safety-related 13 issues that require more analysis or investigation.
14 However, when sr;h issues are identified it is at that 15 time you find the investments that the utility industry 16 has made in research over the last eight years have been 17 focused in the right direction.
I will ask Dr. Rossin of NSAC to report on the 18 tg efforts that EPHI has undertaken on the pressurized 20 thermal shock issue, and he will introduce his 21 associates to report on the programmatic end of this 22 issue and the work that has been committed in order to 23 provide the answers that the Commission is seeking.
MR. HOSSIN4 My name is David Hossin, director 24 25 of nuclear safety analysis center at EPHI.
l l
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NSAC supports the utility industry in 2
evaluating the importance of potential safety problems 3
that have been identified under its generic safety 4
analysis program.
These problems generally have the 5
common following characteristics:
the elements are 6 common to at least several plants; a comprehensive and 7
sophisticated analysis is required --
8 COMMISSIONER AHEARNE:
Dave, what does that 9
mean?
10 MR. ROSSIN:
Well, when we talk about a 11 generic issue and it has priority in our program, we 're 12 looking at something that has significant and long-term 13 impact.
We do a lot of firefighting, too, but I think 14 one of the things that determines priorities on generic 15 issues programs is something that really does have 16 long-term significance.
17 COMMISSIONER AHEARNE:
Should I read number 18 three as saying it could affect future plant designs?
19 MR. ROSSIN:
Yes, and future operation of 20 e xisting plants, certainly.
21 NSAC carries on a continuing evaluation of the 22 importance of generic problems.
When an issue is 23 identified, John Taylor, the diredtor of the nuclear 24 power division, appoints a matrix manager tc ensure a 25 coordinated approach among the various departments of ALDERSoN REPORTING COMPANY. INC.
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the EPRI nuclear power division at NSAC.
2 (Slide.)
3 This brings to bear the parts of research 4
already completed and work that is under way.
The 5
matrix manager also intorfaces with the utilities to 6 ensure technology transfer from EPRI research programs 7 to the utilities which wish to apply the technology to 8
their plants.
9 NSAC was asked to take the matrix management 10 responsibility f or the pressurized thermal shock issue.
11 Mr. Chexal was appointed program manager and appointed 12 Er. Bill Layann as the manager of generic analysis.
13 There are three steps in the generic safety 14 analysis process:
tracking, evaluation and 15 implecentation.
NSAC continues to track nearly 30 16 items.
The following areas have been selected for 17 evaluation in NSAC's generic safety analysis program:
18 reactor vessel pressurized thermal shock, steam 19 generator tube integrity, shutdown heat removal systems, 20 emergency planning for realistic accident sequences, l
ATWS near-term regulatory requirement prioritization, 21 22 and siting criteria.
The long-term potential for neutron 23 embrittlement of reactor vessels has been a recognized 24 25 concern for a number of years.
I might say ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE, S.W., WASHINGTON, D.C. 20024 (202) $54-2345
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1 paren the tically that I first got into this at Argonne 2
more than 25 years ago, along with Cal Shur and Mike 3
Hyder f';om Harwell.
We kind of pioneered the idea of an 4
independent neutron damage function.
That seems like a 5 long time ago.
6 Recently significant attention has been 7 focused on the performance of certain vessels during 8 overcooling transients.
Such an overcooling system can g occur in a variety of ways.These include primary system 10 breaks, secondary system breaks, and excessive feedvater 11 flow.
The likelihood of such a transient posing a real 12 challenge to the reactor vessel is related to the 13 simultaneous occurrence of several conditions:
The reactor vessel material with a very large 14 15 decree of radiation embrittlement.
That is l
18 characterized 'or high reference temper-ture.
We talked 17" about that today.
A crack of sufficle'nt size located in 18 the embrittlement material which could pedbagate high induced thermal stresses could reasonably be caused by ig 20 cold water cascading past the beltline region, and then 21 repressurization of the primary system following thermal 22 shock.
EPRI has been supporting research on reactor 23 24 vessel integrity for the past several years.
This work l
has focused on materials and dosimetry.
However, in 25 l
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June 1981 thermal hydraulics research was expanded and 2
accelerated.
In addition, a cooperative program with 3
four utilities has been initiated to evaluate reactor 4
vessel pressurized thermal shock for four specific 5 plants.
6 This work will help to apply and transfer 7 technology to the utilities and to the PWR manufacturers 8 as well.
9 CHAIRNAN PALLADINO:
These four, Dave, how 10 were they selected?
Did they volunteer?
11 NR. ROSSIN:
Mostly volunteered, but they are 12 also plants that the NRC has devoted attention to.
It 13 was a combination.
.It took both.
14 The principal elements of the EPRI coordinated 15 program are integrity assessment analysis, and this te includes all the properties we've been speaking of, the 17 initial properties of the materials, their composition,^
18 and f racture mechanics and thermal hydraulics testing tg analysis, plant analysis, technology transfer, and remedial actual evaluation.
20 The results of EPRI-sponsored research have 21 been reported at numerous professional meetings that 22 have been published in the peer review literature.
Our 23 integrated program was presented at the last NBC safety 24 information meeting in October 1981, and we held a 25 ALDER $oN REPORTING COMPANY. INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20004 (202) 554-2346
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workshop that was attended by 95 utility and industry 2
representatives.
Our presentation to Dr. Shevmon's 3 Subcommittee on the ACRS was given on December 8.
4 What I'd like to do is introduce you to the 5 individuals who are managing our programs.
I'm going to 6 call on Ted Marston, program manager in the department 7 of systems and materials, to report on the analysis 8 assessment area. He will be followed by Romney Duffey,-
9 program manager in the safety and analysis department, 10 to report on thermal hydraulics testing and analysis, 11 and the work under Rommer's direction by Dr. Bill 12 Sutton.
And Mr. Chexal was matrix manager on this 13 issue.
He will report on plant analysis and technology 14 transfer.
And then Bill Layman, who is the manager, 15 program manager of generic issues analysis, will address te remedial action evaluation and provide concluding 17 remarks.
CHAIRHAN PALLADIN04 Dave, is there work going 18 19 on directly on what decisions the operator has to make as part of the evaluation of these various scenarios?
20 HR. ROSSIN:
In this area of evaluating 21 systems-related issues, wha t we are looking at are what 22 1
things the operator may have to do.
Now, I have been 23 interested in pressure vesseis for a long time and at
~
24 25 1 SAC my primary interest is reactor safety, and of ALDER $oN REPORTING COMPANY. iNC.
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course what we're trying to do is to look at the 2 tradeoff between actions that are designed to ensure 3
that the core remains covered and cool and that the 4
pressure vessel remains within certain temperature 5 limits.
8 We are looking at these things and we are 7 working with people from INPO and the utilities to try 8 and specify the kinds of things you have been talking g about all along today.
10 CHAIRMAN PALLADINO:
That is part of your 11 overall plan?
12 MR. ROSSIN:
Yes.
P 13 CHAIRMAN PALLADINO:
Where will that come up?
14 MR. ROSSIN Mr. Chexal vill touch on this, 15 Yes, but I think you've heard the same thing a couple of 16 times today.
We are looking at these procedures.
We 17 know --
18 CHAIRMAN PALLADINO:
But you are working in 19 this area?
20 HR. ROSSIN:
Yes.
COMMISSIONER AHEARNE:
Dave, you mentioned --
21 22 in regard to INPO, is the specific focus on operator 23 procedures more?
MR. ROSSIN:
Yes, but the safety implications l
24 25 of those procedures is something that we may become l
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deeply involved in.
It depends on the issue, and in 2 this one we're involved.
3 CHAIRNAN PALLADIN0s Where would you say is 4
the lead on trying to examine?
Just by going through 5 your slides and skimming through your material, it 6 seemed you were focusing very much on the materials 7 effects. And if one. vere to ask the question in the 8 review of procedures, how is one examining what 9
procedures are written correctly, would that really be 10 the INPO area?
11 MR. ROSSIN:
The key to this is the whole 12 matrix, the whole systes.
In terms of examining 13 specific procedures, certainly that is more of an INPO 14 obligation than NSAC.
NSAC is trying to look at the 15 safety implications of procedures.
We are trying to 16 define f unctionally what must be done.
17 In a' specific plant with specific controls and 18 specific hardware, there have to be specific l
1 19 procedures.
INPO can look at those procedures to see if 20 they do what they're supposed to do to meet the 21 functional requirements.
COMMISSIONER GILINSKY Could I ask you to 22 23 look at this f rom a little different point of view?
It's in the nature of things that when we get together l
24 1
25 you stress the fact that we 're dealing with something l
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1 which is pretty improbable.
I take that to be the sense 2 of your listing all these things.
And the work is 3 underway and it's reasonably it hand, and I information 4 that, and I don't fault you for that.
5 You don't vant us to' rush off and do something 6 which you would consider rash.
But what do you say when 7 you go to utilities and you explain why it's important 8 for EPRI to work on this?
How do you describe that to 9 them?
10 MR. ROSSIN:
I haven't had any trouble selling 11 that.
12 MR. OWEN :
Can I answer that?
He does not go 13 to the utilities.
He comes to the ove rsigh t committee.
14 COMMISSIONER GILINSKY Wtill, the oversight 15 committee.
What do you --
to MR. OWENs We discuss the potential benefits 17 of what he's doin7 and tell him to go ahead.
Then it's 18 our job to sell the utilities on the fact that we've 19 provided wise judgment in spending the money.
20 COMMISSIONER GIIINSKY:
Let me ask it this 21 vay.
I gather we all think it's important to work on this, but is it because the NBC is so worked up about it 22 l
that it's'important for you to work on it, or what is 23 24 your sense of the problem?
I'd like to have a feel for 25 it.
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MR. ROSSIN:
Well certainly, when thermal shock was 2
identified with regard to transients and the question 3 was raised whether more serious thermal shocks could 4
take place and if so, were there going to be vessel 5 steels which were going to be vulnerable, this raised 6 questions that had not been treated before.
It is one 7 of the things that NSAC is there to do.
It fit our 8 charter, which is to look at our potentially serious 9
events.
There was not any question in our mind that we 10 had to do more work on this subject, and the interest of it the NBC, it seems to me, is just as logical.
12 MR. OWENs I think it is f air to say, Commissioner, 13 that it is more work than we had anticipated, and some 14 of it has been accelerated greatly over the timef rame 15 that.ve originally intended to do the work.
So it is a 16 combir.ation of the two.
I 17 MR. MARSTONa My name is Ted Marston, I am the 18 Manger of the Construction Program at EPRI.
And over 19 the past eight years, as you have heard several times 20 before, EPRI has been sponsoring research activities 21 which we feel are directly applicable to th e 22 demonstration of pressure vessel integrity.
1 23 These include material property genera tion, advanced linear and non-linear fracture mechanics l
24 l
25 development, irradiation damage studies, crack arrest l
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methodology, structursi analysis methods, surveillance 2
capsule testing and analysis, dosimetry evaluation, 3
defect studies and non-destructive examination.
4 The object of the assessment ask which is part of 5
the NSAC program is to integrate the results generated 6
not only by EPRI, but the NBC research arm, the vendor 7
research programs as well as others, and do a s' state-of-the-art procedure test to estimate safe and 9
reliable reactor vessel lifetime.
10 We are concentrating here on this issue assessment 11 on the beltline region of the reactor vessel.
In order 12 to accomplish this objective, three inputs are 13 necessary.
Material properties, principally fracture 14 toughness in this instance, and we would like to knov 15 tha t during the life of the plant.
The stresses applied 16 to the beltline region of the reactor vessel as well as 17 the defects located in this re~gion.
And this is 18 extremely important.
The ingdts must be incorporated 19 into a calculational procedure that models materials 20 behavior as realistically as possible.
21 Today, I would like to highlight briefly three 22 areas material properties, fracture mechanics and 23 thermal anneal.
l 24 The reactor manuf acturers produce vessels with 25 individualized techniques such as forming and welding l
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procedures, materials, et cetera.
The resulting 2
properties of the vessel can vary significantly not only 3
depending on the vessel manufacturer, but the time of 4 fabrication.
To analyze specific vessels, the material 5
properties will represent those of the vessel 6 manufacturer at the time of fabrication.
The estimated 7 changes in these properties will be based upon results 8 developed from reactor experiments and surveillance, e using the correct class of materials.
Embrittlement 10 forecasting vill use best estimate dosimetry.
11 COMMISSIONER AREARNE:
What do you mean by best 12 estimate?
Statistical analysis?
13 HR. MARSTONs We vill rely especially on the owners 14 and vendors for input on dosimetry, although we do have 15 R&D programs backing it up.
16 COMMISSIONER AREARNE:
One of the issues we have 17 debated, not just on this issue, is what does one mean 18 by best estimate.
So I was curious when you said you tg used best estimate.
What did you have?
20 BR. ROSSIN:
When we say best estimate, we mean 21 best and sophisticated analysis, and then I think when 22 you evaluate this in terms of the whole system, you have 23 got to look at the uncertainties in each of the 24 parameters -- certainly, on dosimetry -- and decide wha t 25 it means.
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If you decide you want a conservative conclusion, 2
you may have to allow a certain error or band on that 3 dosimetry and go from the best estimate to something 4
more conservative.
5 But basically, what we are trying to do is to give 6 the most realistic picture we can with error bands 7 wherever they are necessary.
8 COMMISSIONER AHEARNE:
But this best estimate e analysis would be done by the individual' utility?
10 MR. MARSTON They would supply that and we 11 actually use those results in our calculations.
12 MR. ROSSIN:
Let me make clear we are doing a few 13 first-of-a-kind analyses.
We are not going to do this 14 as a routine opera tion.
We are going to try to use the 15 best tools we can and show how they can fit together and 16 what we can do, and we vill not be making any licensing 17 submissions.
The utilities vill be making use of 18 whatever they choose to from our analysis.
1g MR. MARST054 The fracture mechanics calculations 20 vill be based upon stress. calculations derived from 21 transient scenarios and thermal hydraulic assessments of 22 the transient.
The stress calculations have to be 23 performed in sufficient detail to model the anticipated 24 thermal distributions.
The computer program ABAQUS has three dimensional, nonlinar plastic 25 l
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capability.
2 COMMISSIONER AHEARNE:
Does that include a flaw in 3
the clad overlaying a crack?
4 MR. MABSTON:
To my knowledge, cracks have not been 5 observed in the cladding ma terial.
There have been a 6 number of weld defects such as slag occlusion and 7 porosity, but to my, knowledge, that has not been 8 observed.
It certainly can be.
9 COMMISSIONER AHEARNE:
I was more questioning the to modeling that you are doing.
Are you assuming a perfect 11 clad or a flaw in the clad overlaying the crack?
12 MR. MARSTONa If it were no t clear in the 13 presentation, we will be looking at more of what we 14 consider to be more realistic situation.
15 The first situation will be the two-dimensional 16 very long crack that is through the clad.
The next 17 ' calculation will use three; dimensional cracks through 18 the clad, and finally, we will look at cracks underneath 19 the clad.
20 There has been an extensive amount of work --
21 COMMISSIONER AHEARNE:
Yes, I understand tha t.
I 22 was relatino it more to an issue later where one of you 23 is going to say that you are going to look at the 24 possible beneficial aspects of cladding, and I was going I
to ask at that time whether there are any negative 25 ALDERSoN REPCRTING COMPANY. INC.
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aspects which could be if you have a crack all the way 2
through the clad.
3 MR. MARSTON:
That will be part of the intermediate 4 calculation, and you will see a step-by-step benefit of 5
what we consider more realistic assumptions.
6 CHAIRMAN PALLADINO:
You essume that cladding is 7 bonded solidly to the base material?
8 MR. MARSTON:
To my knowledge, I think there is e only one reactor that has anything Lut fusion-velded 10 cladding.
11 CHAIRMAN PALLADINO:
So you are assuming it is 12 bonded.
13 MR._MARSTON:
Yes, I think that is a fair 14 assumption.
There is a f air amount of pre-service 15 inspection cladding to make sure that it is well bonded.
Crackirg ;be'havior will be assessed through the 16 17 transient usiro appropriate initiation and arrest 18 philosophies.
The maximum arrested crack shall be tg transient and plant dependent.
20 The final area of discussion this afternoon is 21 thermal anneal.
A four-year research program is 22 approaching completion.
The program addresses thermal annealing of a. gen'eric reactor vessel, and in this we 23 24 have had extensive laboratory studies.
The research 25 indicates that an anneal of 850 degrees F for 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> ALDERSON REPORTING COMPANY,INC.
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successfully recovers material properties lost to 2
previous radiation embrittlement and minimizes 3
re-exposdre sensitivity.
4 COHNISSIONER. AHEARNEa Is that independent of the 5 naount of radiation, the amount of shift in temperature?
6 MB. MARSTON In th e research program we have 7 looned at three materials, two of which have what we 8 consider to be maximum levels of copper.
The third 9 material has what we consider to be an average level of 10 copper, and these would be typical of both fabrication 11 processes.
12 We have looked at two fluence levels in 13 approximately 23 different material states during the 14 programs, some very extensive statistically designed 15 programs, to assess the embrittlement kinetics, the 16 annealing kinetics, the re-embrittlement kinetics, and 17 the subsequent re-annealing kinetics. ~ I don' t know if 18 tha t ansvers your queation.
ig COHNISSIONER AHEARNE:
I wasn't so much asking on 20 the variety of weld materials and co pper content.
l l
21 Perhaps your two fluences if they are
.the statement 22 here would imply that there is a plateau that is reached 23 that you have reshifted any curves that have shifted, 24 independent of how much radiation exposure had 25 occurred.
Or to put it another way, what was the shift ALDERSoN REPORTING COMPANY,INC, 400 VIRGINtA AVE S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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2
~
MR. MARSTON:
The levels that we looked at would be 3
equivalent to approximately 10 to 20 full power years of 4
operation.
Since this was generic study, we assumed 5 that end-of-life fluence for this assessment was three 19 6 times 10 and we looked at conditions at one times 19 19 7
10 and two times 10 8
MR. ROSSINs Maybe I can clarify.
For a given 9 amount of time at temperature, you can recover a certain 10 amount.
There is a point of dimension return, and it is 11 complex and we have only got a limited number of data 12 points, and we can kind of map what you can accomplish.
13 But there is no simple rule of thumb.
14 COMMISSIONER AHEARNE:
I thought it sounded like 15 there was.
16 COHNISSIONER GIIINSKYa Is this like in-place l
(7 annealing?
You are talking about metallurgy really at 18 this point.
l 19 MR. MARSTON:
There is a systems assessment which I 20 vill get into in just a moment, and ycur question vill 21 be addressed t,here.
Does that cover it?
22 COMMISSIONER AHEARNEa I think that ansvers it.
23 MR. MARSTON:
Fine.
It normally does.
24 The generic assessment, which is -- now we feel 25 that the kinetics of annealing and embrittlement, et ALDERSoN REPORTING COMPANY. INC.
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cetera, have been determined.
2 The question is can you perform such a procedure in 3 an actual reactor.
And of course, our studies are 4 generic in nature, but the contractor in this case is 5 Westinghouse and they made a thorough assessment of the 6 plant design and systems restrictions and in fact, they 7 included reactor vessel design, metallurgical 8 considerations, primary shield concrete degradation, g
reactor coolant piping and equipment supports, reactor 10 vessel intervals, fuel storage and health physics 11 considerations.
Althuugh the ceneric evaluation 12 indicates that there are no plant design or systes 13 restrictions that preclude such an annealing, plant to l
14 plant variations must be considered.
15 In addition to the requirement fC r plant specific 16 evaluations, several vital code and licensing
't7 requirements must be addressed.
l COMMISSIONER AHEARNE:
Such as?
18 MR. MARSTON4 We had a meeting in Orlando with the gg ASSE boiler and pressure section code, and with the NRC 20 staff and the contractor and myself not together and put 21 together a list of such items that should be looked at.
22 23 Would you like me to go through the --
1 COMMISSIONER AHEARNE:
Just give me a few examples.
24 25 MR. MARSTON:
The first question is does the l
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reactor vessel retain its original, qualification, 2
permissible. stress levels,during the annealment, 3 material qualification, inspection requirements and 4 hydro test requirements.
5 There are several NRC considerations that should be 6 addressed; material recovery confirmation, post-anneal 7 surveillance, reactor vessel inspection, biological 8 shield degradation, stresses -- these are just a list 9
that we put together and certainly is not complete.
10 CHAIRMAN PALLADINO:
Have y.ou looked at all those?
11 MR. MARSTON4 From a generic point of view.
But 12 the indications, when you look at the systems at plants 13
-- and this, of course, is Westinghouse again, the two, 14 three and four-loop plants -- that there is enough 15 plant-to-plant variation that a more thorough and 16 indepth look needs to be performed.
37 CHAIRMAN PAllADINO:
What assumption are you making 18 about the way you are going to heat the vessel?
19 MR. MARSTON:
We looked at possibly five different 20 ways of heating the vessel, and of course, resistance 21 heating was the one that was chosen.
22 CHAIRMAN PALLADINO:
What do you mean by resistance 23 heating?
Are you going to have resistance heaters?
24 MR. MARSTONs A heater will be lowered into the 25 reactor vessel.
This is after the internals are ALDERSON REPORTING COMPANY. INC.
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1 removed.
And as was mentioned earlier this morning, we 2
have a topical report that is actually in hand and will' 3
be distributed in the very near future.
4 CHAIRMAN PALLADINO:
Did you examine the i
5 sensitivity to the temperature?
In other words, how at 850.
Why did you pick 850?
6 7
MR. MARSTON:
It turns out once you get above 825 8 you have within a one-week exposure, which is 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />, 9 you will recover essentially all the material properties.
10 CHAIRMAN PALLADINO:
You determined this by tests?
11 MR. MARSTON:
Yes.
12 CHAIRMAN PALLADIN0s Did you look at various 13 tempe ra ture s ?
14 BR. MARSTON:
Yes, as low as 650 degrees F and as 15 high as 850.
We looked at thermal degradation as well 16 as the recovery.
17 CHAIRMAN PALLADINO:
Did you look at anything-18 higher than 8507 39 MR. MARSTON:
No.
20 MR. ROSSINs If you look at the behavior as a 21 function of temperature you will find there are certain 22 characteristics temperatures.
Things don't change very 23 much for a while, and there is a temperature which one reached and things begin to change in shorter times, and 24 25 this has to do with things that are in the At.DERSoN REPCRTING COMPANY,INC, 400 VIRGINIA AVE. S.W., WASHINGTON, D.C. 20024 (202) 554-2345
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microstructure and macrostructure of the metal itself.
2 Above 825 you get a change from below 825, so you 3
know 800 is going to take you a bit more time than 850.
4 I think that is about as well as I can characterize it.
5 When you start getting above 850 degrees you run into e many more engineering problems.
7 CHAIRMAN PALLADINO:
You went to 850 for a reason.
8 MR. ROSSIN:
Because you do it in a week.
It is a 9
round number.
10 CHAIRMAN PALLADINO:
Have you balanced a week 11 versus possible other problems?
The principal reason for not going 13 above 850 was a question of introducing creep strength,
~
14 plastic deformation in the reactor vessel.
We felt by 15 restricting ourselves to 850 the probability of 16 incurring plastic deformation due to creep was minimized.
17 CHAIRMAN PALLADINO:
If you stopped at 825, what 18 would it take?
Three or four weeks?
19 MR. MARSTON:
Once you get in the 825, you will 20 still recover the properties.
21 CHAIRMAN PALLADINO:
AT 800?
22 MR. MARSTON:
Perhaps not.
The 25 degrees was 23 really a cushion.
l 24 MR. OWEN:
There is not much incentive to try to 25 shorten 11rond that.
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CHAIRMAN PALLADIN0s I am just trying to get a feel 2 for how sensitive.
3 COHHISSIONER GILINSKYa How long would the whole 4
process take?
5 MR. MARSTONa The estimate we have in the contract 6 -- again, it is a very rough, generic estimate that if 7 one were to effect an anneal without anything else, it 8 would be approximately a 60-day outage.
9 MR. ROSSIN:
That does not mean you could actually to accomplish it in that period of time.
That might be the 11 critical path ideally.
Well essentially, I think I have 12 summarized, and if there are no further questions.
13 COMMISSIONER ROBERTS:
Any estimates of what the 14 cost would be?
15 HR. MARSTON:
The replacement power cost.would be 18 utility-specific.
The equipment costs run on the order 17 of five million dollars for development of the heating 18 apparatus, the procedure development, the materials tg testing, the requalification, et cetera.
So it is on 20 the order of five million dollars, in addition to the 21 replacement power.
22 MR. ROSSIN:
Let me just put one point in 23 perspective, and that is the questions we have just been 24 discussing would have to be resolved in great detail on 25 a specific basis before a license amendment could be ALDERSON REPORTING COMPANY. INC.
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issued in order to actually conduct this annealing.
And 2
ve are a long way from that point.
3 There are many, many questions that are going to be 4
difficult to answer in order to get that kind of 5 licensing approval.
So we know there are many things 6
that would have to be done before you could say exactly 7 how you are going to do something like this.
8 9
10 11 12 13 14 15 i
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20 l
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MR. DUFFEY:
My name is Hommer Duffey, Program 2
Manager in the Safety Analysis Department at EPHI.
3 Thermal shock analyses rely on an estimation 4
of the fluid temperature and the degree of mixing can 5 significantly affect the degree of thermal shock.
6 Therefore, in June of 1981 ve instituted an experimental 7
program to determine the amount of thermal mixing in the 8 cold leg and the downcomer region utilizing 9
approximately one-fi'fth scale transparent facility.
The 10 major features of BCW, W and CE designs were simulated.
11 The principal objectives of these tests were 12 to generate experimental data for code qualification, 13 support a scaling analysis and to provide data for the 14 assessment of analyses used for plant loop response.
15 Implicitly, all those codes assumed some mixing.
16 We tested several combinations of high 17 pressure injection and loop flows and high pressure 18 injection temperatures.
The results to date indicate 19 substantial mixing of the loop flow with the high 20 pressure injection nozzle by the time that mixture 21 reaches the downcomer, and hence, this potentially 22 limits the extent of thermal shock.
The results of these initial tests have been 23 24 disseminated to the industry on an informal basis, 25 through both quick-look reports and a series of 1
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workshops.
2 CHAIRMAN PALLADIN0s You said this was done in 3
a transparent facility?
Was that glass?
4 MH. DUFFEYa That was plastic.
5 CHAIRMAN PALLADIN0s Could you go to the 6 temperatures you needed to go to?
7 MR. DUFFEY:
They were limited to lower 8 temperatures and hence the lower temperature differences 9 between the injected fluid and the loop flow.
I will 10 turn later to further
-- We did send these results to 11 the staff informally of NHC Research..
We are using 12 these data to qualify the COMMII code which we have been 13 using to assist the fluid temperatures and the 14 velocities in the downconer region.
We also support 15 this by a f ull point two-dimensional test f acility which te also is used to further assess the mixing phenomena and 17 tests in that facility are currently underway.
l 18 And the COMMIX code was initially developed by 19 Argonne National Laboratory for the NBC.
And it is a 20 three-dimensional code with a suitable turbulence i
l 21 model.
The code predictions were compared against the i
22 test data by EPRI, and I must say the comparisons were 23 very encouraging.
COMMISSIONER AHEARNE:
Is that the test data 24 25 rou were speaking about or the one-fif th scale ?
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NR. DUFFEY:.The one-fif th scale.
And also, 2 we now have some initial comparisons with the full 3
height test facility which is two-dimensional.
It is 4 basically a rectangular section, but it has a full 5 height,.10-foot high downconer and a three-foot high 6
pipe section.
7 CHAIRMAN PALLADINO:
Did you determine tne 8 mixing by temperatura measurements?
MR. DUFFEYk Yes.
Temperature measurements 9
10 were made throughout the experiment and in the downcomer 11 region Not only were the physical trains correctly 12 reproduced, but we did obtain reasonable quantitative 13 agreement between the theory and the experiment, 14 especially for the temperature distribution in the 15 downcomer region.
16 What we are doing now is to emphasize further i
17 qualification of the COMMIX code as new data from our 18 programs becomes available, and also the validation of 19 the RETRAN code, the systems analysis developed by EPRI 20 which is used to provide the necessary boundary 21 conditions for the local mixing in the COMMIX code.
22 The experimental program now includes a joint effort with NRC research.
It includes a half-scale test 23 24 facility which we extended the range to 200 psia.
The l
geometries of all PER vendors will be simulated, and we 25 ALDERSoN REPORTING COMPANY. INC.
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intend to conduct a thorough scaling analysis to insure 2
that those results can be extrapolated to prototypical 3
conditions. We are backing this work by our ongoing 4 analyses of reactor system response using large systems 5 codes, and our work on natural circulation cooling.
6 CHAIRMAN PALLADINO:
Does the code take into 7 account the geometry?
The mixing cenerally is pretty 8 geometry-influenced.
9 MR. DUFFEY:
Yes, that is a good point and the 10 COMMIX analysis indeed has to be set up specifically for 11 each geometry, each injection geometry and each 12 downcomer geometry.
And everything becomes 13 design-dependent and specific.
And'the code has that 14 capability.
15 CHAIRMAN PALLADIN0s And so when you say all 16 of the PWR vessel geometries will be simulated, do you 17 mean both in the code'and in the test?
18 MR. DUFFEY:
Both in the code and in the 19 test.
The tests presently are configured with one cold 20 leg and a downcomer section.
The objectives of the work 21 are to provide experimental steady-state and transient 22 data on thermal mixing in the cold leg and downconer 23 cegion due to safety injection.
And we intend to use 24 this to not only understand mixing, but to develop heat transfer correlations and thermal mixing models; to 25 ALDERSoN REPORTING COMPANY. INC.
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)
1 provide data for code assessment; to provide scaling 2 rationale to apply data to reactor conditions; and in 3
conjunction with NRC and their contractors, to develop, 4 assess and improve the turbulent mixing models which 5 exist in computer codes.
6 The larger test program will start in April 7 and is expected to last 20 months.
And that is our 8 basic experimental an'alytical program on thermal mixing.
9 COMMISSIONER GILINSKY I wonder if I could 10 ask a question now instead of at the end of your 11 presentation.
I am unfortunately going to have to 12 leave, and I apologize.
13 You seem to be doing a lot of fancy things, 14 but I don't see any work on what was earlier called fuel 15 management schemes.
Is that regarded as something that 18 the utilities have well in hand and it doesn't have to 17 ~be done by EPRI?
18 MR. lAYMANs I will touch on some of those 19 schemes at the conclusion.
20 COMMISSIONER GILINSKYa Because it does seem
~
21 to be a simple way of avoiding all of these problems.
22 MR. LAYMANs It is not quite that simple.
23 MR. ROSSIN:
It is not simple; it is extremely 24 plant-specific in the licensing requirements and the 25 commercial involvements in ordering fuel, specifying and l
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obtaining fuel really are things that require many years 2
of lead time.
3 These are going to be done by specific 4 utilities and their consultants, whether they are the 5 field manufacturer or whoever they use to do their fuel 6 analysis.
And there are an awful lot of tradeoffs 7 involved.
It is not something we even have the 8 capability to do.
9 The kinds of licensing analyses or fuel 10 analyses, even though EPRI was involved in developing 11 some of the computer programs that the utilities do 12 use.
But this is a totally utility-specific thing that 13 will have to be done by -- well, it is done routinely by 14 all the utilities f or all their fuel planning.
And ther 15 look at options and if they are going to consider this 16 option they will do their parametric analysis on it to 17 decide what they can do.
18 MR. OWENs It is a long-term kind of change, 19 particularly if you are talking about going from the 20 12-month to the 18-mon th cycle.
We have been working 21 more than three years and are well into a transiti7n on 22 Oconee to an 18-month fuel cycle.
We have been at it l
2j for more than three years now.
CHAIRMAN PALLADINO.
How much does that l
24 25 improve your embrittlement picture?
In other words, do ALDERSoN REPORT 1NG COMPANY. INC.
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you --
2 HR. LAIMANs Somebody mentioned earlier today 3
it is a 25% to 35% improvement.
4 HR. ROSSIN:
In terms of end-of-life 5
expectancy it can make that auch difference.
6 CHAIRMAN PALLADIN0s 28% more time before you 7 reach a given fluence?
8 MR. ROSSIN:
Yes.
9 MR. LAYMANs Commissioner Gilinsky, we have 10 looked a t the f uel shuffling, or the effect on fuel just 11 in enough detail now to have a number of questions that 12 we know have to be answered, which we know cannot be 13 answered quickly or simply.
The fuel-related concerns 14 include zircaloy, water side corrosion changes because 15 of this change.
You are changing the fuel performance.
16 We need to look at fuel failures following
^
17 gover increases, zircalor hydriting, thermal margins,
(
18 stored heat for all of the transient analyses and safety l
tg analyses.
These are all things that can be done, but 20 they all dictate that this is not a simple solution.
21 CONHISSIONER GILINSKYs I did not mean to 22 suggest it was trivial..
Nothing involved with moving 23 things around in reactors is.
But when you start 24 talking about the possible prospect of annealing, by 25 comparison I would say it is a pretty simple thing to be ALDERSoN REPCRTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554-2345
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doing.
2 HR. ROSSIN:
Neither is simple, but I think 3 you are right in that kind of comparison.
But you have 4
also got to examine whether -- what the available 5 benefit is.
It may be 28% in one particular case where 6 they have analyzed it.
It may be only a few percent in 7 ano ther case.
That may be all the potential that is 8 availble.
9 In other cases there may be more potential.
10 CHAIRMAN PALLADINO:
.28 percent.
11 COMMISSIONER GILINSKY:
I spoke to one utility 12 looking at a scheme that involved putting the higher 13 burnt-up fuel on the outside, and I thought it was 14 something like a factor of three at the veld.
15 MR. ROSSIN:
In terms of the effective full 16 power yers, the total contribution that could be made on 17 that reactor at this time might be a few percent, and if 18 it can only make a marginal contribution I do not think
-~
19 COMMISSIONER GILINSKY:
That's 3 percent.
20 21 MR. ROSSINs A reactor that has been opera ting for a number of years -- a change made at this point may 22 be able to contribute a very small amount at the end of 23 24 life fluence CHAIRMAN PALLADIMO:
That is not the picture 25 ALDERSoN REPORTING COkPANY,INC, 400 VIRGINIA AVE, S.W WASHINGTON, D.C. 20024 (202) 554 2345
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we got as a possibility this morning.
2 MR. ROSSIN:
There may be some that have good 3
potential.
There may be others that do not.
That is 4 why we have been stressing the plant-specific nature of 5
this question.
And again, you know, if the entire life 6 of the plant -- the effective lifetime of the plant can 7 be assured and you don't reach the fluence level that 8 you are concerned about, then you do not want to make a 9 change like this when you do not need to.
10 COMMISSIONER GILINSKY:
Yes, but you know, if 11 there is one thing I would be worriad about if I owned 12 one of these plants it is a crack li
.he pressure 13 vessel.
You can cope with all kinds oi things, cracks 14 in pipes, we have got pumps and systems already to go 15 but I would sure want to stay as far away as I could 16 from one of these cracks, quite apart from any safety --
17 MR. ROSSIN:
I think we share that concern.
18 19 20 21 22 23 24 25 ALDERSCN REPORTING COMPANY. INC.
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NR. OWEN I think we are confident that we 2
are a good ways from there and that we have the ability 3
to make a good decision as opposed to one that we will 4 be undoing in a short period of time or could be undoing 5
in a short period of time.
6 COMMISSIONER GILINSKY:
Well, in pointing to 7
these schemes that have been discussed about addressing 8 the way the fuel is distributed, I didn't feel that was 9 necessarily the solution, but it does seem to be 10 something that stretches out the time scale.
And I 11 would have thought that whatever else you do that seems 12 to be the thing to be doinc.
13 HR. ROSSIN:
It's an option, but it can 't be 14 done like that.
15 COMMISSIONER GILINSKY No.
I know it can't 16 be done'like that, but -- well, I think there are 17 vendors that are offering schemes of that sort right 1
18 now, aren't there?
19 MR. ROSSIN:
Do you know how long it takes to 20 license a fuel reload?
21 COHNISSIONER GILINSKY:
No.
You have me at a 22 disadvantage here.
23 MR. ROSSIN:
Barbe we're reversed.
24 (Laughter.)
25 COMMISSIONER GILINSKY:
I thought at least in ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE, S.W. WASHINGTON, D.C. 20024 (202) 554 2345
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one case they were talking about the next reload, and 2
they were talking to a vendor who was offering a scheme 3
of this sort.
4 M,H. CHEXAL:
It has to be done on a plant 5
specific basis.
It's part of the options that we look 6
at, and we will get into the plant specific part and 7 look at. potential options.
8 CHAIRMAN PALLADINO:
I wonder if I could ask 9
Mr. Dudley one question.
You say you picked the 10 temperature differences to represent the situation.
11 MR. DUFFEY :
Yes.
We did a scaling analysis 12 where we attempted to represent the correct 13 nondimensional groups.
We are a little blank in our 14 present experiments, which ic why we seem to need some 15 further experiments.
16 CHAIRMAN PALLADIN04 Do you cover the case of
~
~
17 formed or heated ECS7 18 MR. DUFFEY:
Yes.
We've covered the range of 19 different temperature differences.
20 (A t 4:08 p.m., Commissioner Gilinsky left the 21 room.)
22 CHAIRMAN PALLADINO:
So if that were the route 23 that were followed, you'd have some information on that 24 mixing.
25 MB. DUFFEY:
That is correct.
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1 BR. CHEXAL:
I as matrix manager coordinating 2 all EPHI-NS AC activities on the reactor vessel thermal 3
shock program.
4 EPHI is in the final stages of developing a 5 linked set of codes and qualifyng them to perform 6
reactor vessel pressurized thermal shock analysis.
In 7 order to transfer the package of thermal hydraulic and 8 structural technology to the industry, EPEI has 9 established cooperative programs with four utilities to 10 address reactor vessel pressurized thermal shock 11 concerns at four specific reactor plants.
This includes 12 one from each of the PWR vendors.
13 The objective of this program is to assess 14 with reasonable assumptions and best estimate 15 calculations the integrity of reactor vessels over their 16 design lifetime.
In addition, these models can then be 17 used by the utilities for selection of limiting events, 18 analysis of their plant behavior and vessel integrity, 19 avaulation of the need for an efficacy of system 20 modifications, development of improved operation 21 strategies, and investigation of the effects of multiple 22 failures and operator errors.
23 The main tasks involved in performing the 24 plant speciic analysis are:
plant specific data 25 collection; system loop flow and temperature ALDER $oN REPORTING COMPANY. INC.
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calculations for the cold leg using the RETRAN computer 2 code for, the selected transient; fluid and thermal 3 mixing calculations for the cold leg and downcomer using 4
the COMMIX code to determine the transient fluid 5 temperature and. velocity history at the various 6
locations on the vessel vall;. transient heat transfer 7 coefficient calculations for the fluid-wall interface; 8 identification of critical welds based on geometry, 9 location, copper, phosophorous and nickel content and 10 RT values.
NDT 11 Future models will perform. thermal analysis 12 using the ABAQUS code and generate 3D temperature 13 profiles and then three-dimensional stress patterns as a 14 function of time.
Then to perform the stress intensity 15 calculations.
The restraining effect of the clad will 16 also be estimated.
17 COMMISSIdNER AHEARNE:
That is there I was 18 going to ask my question.
Will you be considering cases 19 only where the clad acted as a restraining effect?
20 MB. MARSTON:
No.
As I mentioned, we'll be l
21 doing the calculations and looking at the full spectrum.
l 22 MR. CHEXAL:
To generate fracture toughness 23 profiles for initiation and arrest conditions.
Failure 24 predictions will be made using furst the onset of l
25 initiation, and second where initiation is permitted but ALDERSON REPoRDNG COMPANY. !NC.
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/
1 arrest must be demonstrated within X percen t of the 2
vall, X being a function of the repressurization level.
3 The results will be presented for the selected 4
transient to provide an estimate of the operational time 5 permitted before initiation is expected, and operational 6 time permitted before initiation and arrest is expected.
7 And the package will be transferred to the 8 utilities as a part of technology transfer to the 9 utilities.
10 CHAIRMAN PALLADINO:
When will you transfer it 11 to them?
12 MR. CHEIAL:
We will be developing the models 13 that will be developed for their specific plants, and we 14 will also be providing them the knowledge of how to 15 utilize these models, and also to have them get the 16 ability to do sensitivity type analysis calculations for
~ 17 ' their purpose.
18 CHAIRMAN PALLADINO:
So they would take these l
19 tools and then make their own analysis for their own 20 specific --
21 MR. LAYHAN:
We will go through the early 22 analyses with them.
23 CHAIRMAN PALLADINO:
Do the utilities have l
24 this kind of capability or do they contract it out?
25 MR. CHEXAL:
We believe they have that t
i ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554-2345
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capability.
2 MR. LAYMANs These particular utilities are 3
anxious to develop the capability.
4 CHAIRMAN PALLADINO:
Are all your utilities 5
anxious to do that?
6 MR. LAYMAN:
We haven't talked to all of 7
them.
We have talked to these four specific utilities, 8
and they are anxious to participate.
3 CHAIRMAN PALLADINO:
I know there are some to utilities who have gotten quite sophisticated, but my 11 impression is not that all utilities are that 12 sophisticated or even interested in becoming as 13 sophisticated.
14 MR. LAYMANs Surely not all these utilities 15 have this degree or capability.
16 MR. HOSSIN:
There's a vide diversion.
Some 17 make more use of consultants than others.
Some have big 18 in-house departments; others don't.
19 CHAIRMAN PALLADINO:
Well, that's one of the I'm not sure that these 20 concerns I have is that the 21 things get the same level of attention from every 22 utility.
23 MR. ROSSIN:
I believe there's no perfect way l
24 to do this.
I think these diverse ways each have their 25 own pluses and minuses.
Some work very well and some ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W. WASHINGTON. D.C. 20024 (202) 554 2345
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who say use exactly the same organizational structure 2 don't work as well, so there's no magic way to do it.
3 COMMISSIONER AHEARNE:
What is the sort of 4
time scale that you have in this program for the 5 completion of all the results and being read; for the 6
transfer?
7 MR. CHEXAL We believe for the first plant, 8 which is Maine Yankee, we will have the results around 9
somewhere this year, but that is for the first plant.
10 COMMISSIONER AHEARNE:
I'm talking about this 11 completion.
You've gone through a program development 12 and what you 're going to have developed, the models 13 checked, the models developed, the methods of 14 application, and finally reach a stage where you will 15 transfer, which would, I would assume, then cone to 16 these plants post phse 4.
You're using these as sort of 17 a testing developmental set.
18 MR. CHEXAL The codes have been developed, 19 and some of the coder have already gone through.the 20 qualification process.
And as Dr. Duffey pointed out, 21 COMMIX has gone through some validation and is going 22 through further validation.
What we are doing is 2'3 working on plant specific model development.
24 MR. LAIMANs We expect to have completed the 25 transfer of technology to the user utilities by early l
l ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. O.C. 20024 (202) 554-2345 l
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next year.
2 My name is Bill layman, canager of generic 3 safety analyses at NSAC.
To complete our EPRI thermal 4
shock program I will address the area of remedial action 5 evaluation.
Among these, vessel annealing is the most 6
exotic.
7 We believe there is a reasonable probability 8
that results from research and development efforts will 9
demonstrate that with reasonable ~ assumptions and best 10 estimate calculations tha safety of even the older 11 reactor vessels with high copper welds can be assured 12 over their design lifetimes without the necessity of 13 performing such exotic fixes.
14 COMMISSIONER AHEARNEs Mr. Layman, what do you 15 sean by " exotic?"
16 MR. LAYMANs I would use what I believe is the 17 dictionary definition of it's foreign, it's fore'ign 'to
^
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18 do this kind of heat treatment inside an existing plant 19 at this point in tise.
That doesn't mean that in the 20 future it cannot be done.
I think as Ted Marston 21 described, we think that the technical feasibility has 22 been shown, but it's exotic just because at this time 23 it's foreign.
24 COMMISSIONER AHEARNE:
So that anything -- I 25 don't want to belabor it.
It just sounds to me tha t th e ALDERSoN REPORTING COMPANY. INC.
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equivalent would be expensive and at the moment thought 2
unnecessary.
3 MR. LAYMAN:
No.
I don't believe that's the 4
dictionary definition.
5 COMMISSIONER AHEARNE:
I know.
6 (Laughter.)
7 It night be a replacement.
8 MR. LAYMANs Several other people in our group 9 asked me what I meant by " exotic," and I think I was 10 relying on what I believed is the dictionary definition 11 of exotic.
I'll go back and look it up for you, though.
12 In spite of our confidence in getting the 13 design lifetime without the necessity of such tests, we 14 have a significant program to investigate the 15 feasibility and practicality of vessel annealing.
A 16 preliminary report of this work has been presented to 17 the NRC staff and the appropriate ASME code committee.
18 As Ted mentioned earlier, the practicality of vessel 19 annealing and continued licenseability of an annealed 20 vessel remains to be established.
21 Modified procedures, design and operation will 22 be considered during our plant transient analyses.
23 This answers another one of the questions that 24 you asked earlier, Commissioner Ahearne.
25 This would help individual utilities to tailor ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE. S.W., WASHINGTON, D.C. 20024 (202) 554-2345
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1 modifications on s plant-by-plant basis if necessary.
2 To conclude our presentation we would state 3
that the utilities are serious about the pressurized 4
thermal shock problem and through EPRI and the vendors 5 have dedicated a significant effort to its resolution.
6 Important research program results exist now 7
which have not been incorporated yet into the regulatory 8 process.
A prime example of this is the question of how 9 to apply warm prestress in the analysis of pressurized to thermal shock.
11 We are anxious to cooperate with the NBC staff 12 and keep them informed as our programs achieve results.
13 We believe tha,t our research base and applications 14 efforts may help to provide a firmer technical 15 fou'ndation f or decisions by industry and the NRC.
i 4
i l
16 CHAIBHAN PALLADINO:
I would like to ask two 17 general questions, or maybe they are observations that I-18 want to make sure are either confirmed or are put to 19 rest.
20 One has to do with the industry.
Is either 21 AIF or EPRI or anyone else really looking at the 22 competing operational decisions that a reactor operator 23 has to make in each specific plant in examining th'e 24 question of whether or not, A) one can develop 25 procedures that would be not conf using, and B) can the ALDERSoN REPoRUNG CCMPANY. INC, 400 VIRGINIA AVE., S.W', WASHINGTON, D.C. 20024 (202) 554 2348
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symptoms be so described that you know what procedure to i
2 usa?
~.
3 And 'I am not' clear that I get a strong feeling 4 that that's going on in the industry.
Maybe I'm wrong.
5 I didn't get it from these discussions.
8 MR. LAYNAN I believe you didn't get.it just 7 'because of the group that you're talking to.
For 0 Ansta'nce, EPRI has been looking at solutions that are 9 main 17' not the operator and control room interf ace.
10 I
CHAIRMAN PALLADINO:
Well, you did talk about 11 modified procedures, design operation will be 12 considered.
And I almost
~~pped you there because I 13 don ' t know wha t was con._.ored.
14 HR. LAYMANs As we go through the it.dividual 15 plant analyses as we go through our experimental work, i
16 many times taere are things that will obviously change a
~
17 ~ transient.
De will look at transient sensitivity to 18 these changes'a'nd determine if these various procedural 19 ' changes would ' be neff ective from our' analysis.
The 20 actual transmittirc'of tha t from that stage ~into 21 checking cherating pr,ccedures will be done with ' the 22 utilities, rendors and the various industry groups..
M R. ON E.} 4 Mr. Chairman, that's not really an 23
~
24 area that I have been heavily involved in for the 25 industry,'but'I do believe that in the last cocple cf i
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years there has been a concerted effort by all of the 2
utilities to look at the symptom-oriented procedures 3
that Jim Taylor referred to earlier.
All of that came 4 out of our concern following THI, and every utility and l
5 every owners group has had an effort under way.
Each 6 one has called it a little something differently.
7 In the last couple of months or a little 8 longer than that, I guess, if my memory serves me 9
properly, INPO has brought together all of those owners to groups to look upecifically at the issue that you're 11 talking about and make sure that we are trading best 12 experience in these kinds of procedure revisions to do 13 the very best job possible.
14 CHAIBHAN PA1LADIN0s I was thinking handling l
15 not only pressurized shock -- there is a procedure to 16 handle pressurized thermal shock.
That's well 17 characterized, and'you come up with procedures here 's 18 what you do if you have pressurized thermal shock.
But l
l 19 then there's some other incident that might take place 10 and it's got a different procedure, and then'another 21 e ve nt. tnat would take place and it's got a different l
22 procedure.
23 I was wondering are the utilities or are the l
24 vendors or somebody that's appropriate looking to see 25 that the things are well enough characterized by ALDERSoN REPORTING COMPANY,INC.
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1 symptoms so that you don't have to decide whether this 2
is this kind of an accident or that kind of an accident?
3 MR. LAYMANs We know they are looking at them, 4
and we participated with them in the SPDS.
5 MR. OWENs That's the symptom or unit 6
procedures, and the reason it takes time is the very 7 point you're making :
that there's almost always some 8 sort of tradeoff or at least you want to look to see if 9
there's some sort of tradeoff when you start making 10 these kinds of changes in your procedures.
11 So there's a great deal of work going on, and 12 as Bill said, we're just not the right group to talk to 13 you about that.
14 MR. DUFFEY :
There is work in the industry, 15 too, in relation to monitoring the critical functions lo and the operator control room and operator aides area,
~
17 which also has an important bearing on this question.
18 COMMISSIONER AHEARNE:
When you say you're not 19 the right group to talk to us, would that be INPO?
20 MR. OWEN:
The four owners groups have 21 recently combined their efforts at INPO.
I would just l
l 22 have to give you an individual's name, and I'll be happy l
23 to do that.
24 MR. LAYMANs We, for instance, though have a 25 group in NSAC looking at the safety panel display system 1
ALDERSoN REPORTING COMPANY,INC.
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which addresses this same point.
We did not bring that 2
talent with us today because we didn't realite it would 3
be a topic of discussion.
4 CHAIRMAN PALLADINO:
The other observation has 5
to do with the point that Commissioner Gilinsky has 6 pressed a number of times.
Based on what we heard from 7
the staff this morning one of the more promising ways of 8 perhaps coping with the problem is by lov leakage core 9
other than just the 18-month cycle, but actually doing 10 something to the f uel elements in the core.
And I don't 11 get a strong feeling -- I don't get a feeling that 12 serious research in that area is going on.
13 MR. ROSSIN:
Joe, I don't believe it's really 14 a research problem.
I think these analyses are 15 relatively straightf orward.
I think the point we're 16 trying to make is very complex.
It's not clear to 17 everybody just exactly what would serve best because 18 there are tradeoffs in every case.
And the urgency for 19 doing this is not quite, as Commissionec Gilinsky 20 implied, that you want to do everything you can right 21 now to try and take care of this problem.
One year, 22 plus or minus, is not going to change the picture 23 significantly.
24 CHAIRMAN PALLADINO:
The use of the word 25 "research," maybe the way I used it may not be the same, ALDER $oN REPORTING COMPANY,INC, 400 VIRG!NIA AVE., S.W., WASHINGToti, D.C. 20024 (202) 564-2346
r 91 1
which addresses this same point.
We did no t bring that 2
talent with us today because we didn't realize it would 3
be a topic of discussion.
4 CHAIRMAN PALLADINO:
The other observation has 5
to do with the point that Commissioner Gilinsky has 6 pressed a number of times.
Based on what we heard from 7
the staff this morning one of the more promising ways of 8 perhaps coping with the problem is by low leakage core 9 other than just the 18-month cycle, but actually doing 10 something to the f uel elements in the core.
And I don't 11 get a strong feeling -- I don't get a feeling that 12 serious research in that area is going on.
13 NR. ROSSIN:
Joe, I don't believe it's really 14 a research problem.
I think these analyses are 15 relatively straightf orward.
I think the. point we're 18 trying to make is very complex.
It's not clear to 17 everybody'just exactly wha t would serve best because 18 there are tradeoffs in every case.
And the urgency for 19 doing this is not quite, as Commissioner Gilinsky 20 implied, that you want to do everything you can right
{
21 now to try and take care of this problem.
One year, I
l 22 plus or minus, is not going to change the picture 23 significantly.
l 24 CHAIRMAN PALLADIN0s The use of the word 25 "research," maybe the way I used it may not be the same, I
ALDERSCN REPORTING COMPANY,INC.
400 VIRGINIA AVE 3.W., WASHINGTON, D.C. 20024 (202) 554-2346
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but the staff talks about making recommenda tions to us 2 on steps that would be prudent to take at this time.
3 And one of the things I read are things like warming up 4 ECCS, doing something with the perfora ted core, and then 5 ve get to the more " exotic" issues, and.I don't see the 6 work that's going on that's going to help us answer this 7 question.
8 ER. ROSSIN:
I think you will see some of that 9 by this summer.
10 CHAIRMAN PALLADINO:
That's why I was pointing 11 to the two items, one of which has to do with the lov 12 leakage core.
13 MR. LAYNANs I think it's imperative that we 14 not get into what I would call problem hopping, moving a 15 reactor vessel problem and solving that one by creating to a fuel problem.
17 CHAIRMAN PALLADIN04 That's what I say.
Some 18 vork ought to be going on.
19 MR. LAYEANs I believe there is.
20 CHAIREAN PALLADINO:
I don't feel there is 21 work going on, and I'm not trying to be critical.
I'm l
22 just trying to get us directed to where when we have to 23 face'some decisions --
24 HR. LAYMAN We have done some very secping 25 type analyses which would indica te, for instance, if we ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTCN, D.C. 20G24 (202) 554-2345
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93 1
replace the outer fuel with dummy elements that you 2
might get a lot larger decrease in flux.
You might get 3
a factor of 10, but you might also get a penalty of 10 4
and a loss of margin in reector thermal characteristics, 5
and most of the reactors cannot afford to lose that kind 6 of margin.
7 MR. OWENs Let us do that.
Rather than 8
speculate about wha t's being done, I know a number of 9
utilities are l'ooking at the 18-month cycle which we 10 were looking at for different reasons.
We haven't spent 11 any time personally on this problem, but we will have 12 through NSAC -- find out how much is going on in that 13 area.
It is highly utility specific.
14 MR. ROSSIN:
Mr. Chairman, we hope to come 15 hack and see you again when we have results to report 1E this summer, and we would like to keep in touch with the j
17 staff and will keep them informed on what-we're able to 13 learn about the progress in these various areas.
19 CHAIRMAN PALLADIN0s Any other comments?
20 COMMISSIONER AHEARNE:
I'd make a comment.
I 21 imagine, Dave, that if the staf f goes on the path they l
l 22 seem to be committed to, they will be coming in in June 23 with recommendations, and I'm sure industry will want to l
24 come in and bring us up to date.
23 CHAIRMAN PALLADIN0s Well, I thank you very l
ALCERSoN REPORTING COMPANY,INC, l
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1' 94
- s 1
auch.
I think we have learned quite a bit this 2
afternoon.
I aa heartened by the work that is going 3
on.
I don't mean only to be critical.
I do appreciate 4
the important effort that's being aade, and I think it's 5 all in our mutual best interest.
6 Okay.
Thank you.
7 We stand adjourned.
8 (Whereupon, at 4:30 p.a.,
the aceting was 9 adjourned.)
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 ALDERSON AEPORTING. COMPANY,INC, 400 VIRGINIA AVE., S.W. WASHINGTON. D.C. 20024 (202) 554 2345
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COMMISSION MEETING in the C&Cter" cf:.
PUBLIC, MEETING - BRIEFING BY AIF AND EPRI ON PRESSURIZED THERMAL SHOCK Date cf Prcceeding:-
' March 9, 1982 Ocekee llumber:-
Place of Preceeding:
Washington, D. C.
were: held. as hereis appears, and that this L3 the cetzt:aL transc:-i cherecf fer-the fil.a cf the Com:ri.scisc.,
Ann Riley Official Espcmar- (Trped)
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