ML20005E820

Forwards Minutes of NRC 890907 Meeting W/Util in Rockville,Md Re Util LOCA Analysis Program.List of Attendees Also Encl

ML20005E820
Person / Time
Site:	Vermont Yankee
Issue date:	01/02/1990
From:	Tremblay L VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-90-003, BVY-90-3, NUDOCS 9001110123
Download: ML20005E820 (6)

Text

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.c g P JVERMONT YANKEE BvY 90-003-e JNUCLEAR POWER: CORPORATION

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Ferry Road, Esrattleboro, VT 05301-7002 ENGINEERING OFFICE ,

580 MAIN STREET BOLTON, M A 01740 (508)779 6711 .i January 2,1990

, ' United States Nuclear Regulatory Commission Document Control Desk Washington,'DC 20555

References:

a. License No. DPR-28 (Docket No. 50-271)

Subject:

Vermom Yankee LOCA Analysis Program Meeting Minutes i

Dear Sir:

i Attached please find minutes for the subject meeting which was held between NRC Staff and  !

Yankee Atomic personnel at NRC Headquarters in Rockville, MD on September 7,1989.- The purpose of the meeting was to discuss the status of the Vermont Yankee LOCA Analysis Program.

Should you have any questions with the attached information, please contact this office, o

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.t Very truly yours, l p

, VEJtMONT YANKEE NUCLEAR POWER CORPORATION edo, d S.

Leonard A. Tremblay, Jr.

Senior Licensing Engineer l

L L cc: USNRC Region I Administrator USNRC Resident Inspector- VYNPS USNRC Project Manager- VYNPS p

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YAEC/NRC MEETING ON VERMONT YANKEE LOCA ANALYSIS PROGRAM SEPTEMBER 7, 1989. AT NRC: f

Participants:

- YAEC N.RC

. Mort Fairtile Mike Marian Wayne Hodges Steve Schultz '

T . Bob Jones . Bruce Slifer Gene Hsii ' Tom Fernandez George Thomas Liliane Schor '

Ramu Sundaram -

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- XAEC/NRC MEETING ON VERMONT YAliKEE

. LOCA ANALYSIS PROGRAM SEPTEMBER 7. 1989 y -

1. Objective was to discuss the status of the Vermont Yankee LOCA Analysis Program, including background history, details on Vermont Yankee LOCA l Licensing Application plan method, status of ongoing Vermont Yankee LOCA l analysis work at YAEC and submittal / review schedules. '

2.. Presentations were made by YAEC on the~following topics:

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a. Overview - discussion of need for improved LOCA analysis for Vermont

-Yankee from perspectives of plant safety, licensing and plant economics.

b.- . History of YAEC/ Vermont Yankee LOCA Analysis Program - Summary of activities-from 1979 to present including YAEC development i milestones, submittals to NRC, interactions with NRC, outstanding issues,

c. Vermont Yankee.LOCA Analysis Application Method - Details of YAEC approach outlined in October 1988 submittal (Report YAEC-1638P).

d. Vermont Yankee LOCA Analysis Work Status - Status of work at YAEC since October 1988;

3. Summary of discussion.

a. NRC has limited review resources, currently have about 70 topical reports to review, looking for ways to prioritize reviews, have resources only for about 20 reviews by June 1990. NRC feels that safety and operational considerations should have higher prioritization than' economic considerations. YAEC needs to make

'their case for why a new LOCA analysis program is important for Vermont Yankee. NRC will then optimize review resources based on

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(1) YAEC/ Vermont Yankee needs relative to others, and-(2) ease of review of YAEC methods.

b. YAEC approach is-based on SECY-83-472. NRC feels that this approach would require an extensive review lasting at least a year.

c. On YAEC method outlined in October 1988 submittal.

(i) NRC has done a quick review and has several concerns, described below. '

(ii) YAEC needs to look at the new Appendix K rule, the Regulatory Guide (1.157) for the rule, and the CSAU methodology, and address all the issues outlined. Those include a more detailed treatment of the code modeling uncertainty (comparisons to variety of data, scaling effects between tests and plant, multi-dimensional effects at plant scale, compensating code errors, and error propagation during a LOCA transient).

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\^ IAEC/NRC MEETING'ON VERMONT YANKEE LOCA ANALYSIS PROGRAM SEPTEMBER 7. 1989 p (Continued)-

h (iii)'On c' ode uncertainty YAEC should look at APCT in TLTA-assessment on an elevation-by-elevation basis. This would expose phenonena that may.be masked otherwise. .

I' (iv) -Some code models may have to beLtreated as uncertainties if not adequately benchmarked. A typical example is the Zr-H O2 reaction model at temperatures above 1600'F..

(v)1 'A separate models/ correlations document may be needed. This would'(a) describe the significant code models and.(b) assess

.model uncertainties and adequacy.

(vi) Since the YAEC method is based on SECY 83-472, where the  !

evaluation modal is still based on Appendix K required features, the apper bound analysis does not have to be l justified using sophisticated statistical methods..- Good'-

engineering judgment and appropriate sensitivity studies may.  !

be used to arrive at a PCT that is bounded at the 95%

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- probability level or higher. Note that a more deterministic approach can be used. This would yield higher PCT, but can be ,

analytically simpler and easier to review. ,

1 l (vii) The RMS method of combining uncertainties, as outlined in the YAEC method needs to be justified.

(viii)There are some results in the CSAU methodology application for  !

PWRs that can be applied to BWRs also, YAEC may take i

advantage of this. A typical example-is justification of nodalization.

-(d) On work performed at YAEC since October 1988 submittal.

(i) The BE break spectrum looks good. It can be approved quickly if needed because it is backed up by the SER.

(ii) YAEC should look at nodalization sensitivities at the limiting (0.7 ft2) break' also, not just at the DEG break.

L (e) On-alternatives.

i l l, (i) Vermont Yanwee could go to GE for analysis - not desirable i route for YAEC. Also not necessarily most desirable for NRC l because it takes away from building in-house utility expertise on safety issues.

l; (ii) YAEC could come in under strict EM calculation. RELAP5YA should be okay for this except for a few minor features covered in the SER. NRC thinks that with a few modifications YAEC could use RELAP5YA for EM analysis. If so, the review L would be a lot easier. Vermont Yankee may incur a loss of 1'

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. LOCA ANALYSIS PROGRAM SEPTEMBER 7. 1989 (Ocntinued) margin because of added conservatism, but the margin may be sufficient. This needs to be further explored. Because of ease of_ review, this.might be a very attractive option for YAEC.

(f) On the review process:

(i) The[WandGEreviews_(SECY83-472 approach)tookabouttwo-years including very frequent NRC interactions. YAEC is starting at a more advanced level than W and GE and also has the~new Appendix K and Regulatory Guide 1.157, and so has a more_well-defined path to follow. However, a review time of at least one year can be expected. NRC will. inform ACRS before issuing final SER, but do not expect to get into detailed ACRS review. Note, however, that-ACRS is very interested in LOCA issues.and has a staff that may be currently under-utilized. So they may take an active interest in YAEC.

(ii) Because the review is Vermont Yankee specific, the NRC does i not anticipate needing CRGR review, so we save ~2 months.

(iii) Best bet is for YAEC and NRC to have frequent meetings. There will be a lot of areas where compromise positions may be necessary. Hence, YAEC should not plan to only submit reports at specified times.

H (iv) NRC's quick review of YAEC-1638P says it is not adequate. YAEC should plan to resubmit it after a few iterations with NRC.

(v) NRC will make a reviewer available around September 18, 1989.

The reviewer will periodically consult Gene Hsii because of Gene's experience with the W,SECY 83-472 review. Possible reviewers include Warren Lyon.

ACTIDH

- NRC:

(1) Assign reviewer by September 11, 1989.

' (2) Review SER on RELAP5YA to see why RELAP5YA was not accepted as EM using Appendix K required features, and what needs to be done to make it so.

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IAEC/NEC_MEEIING ON VERMONT YANEEE i LOCA ANALYSIS PROGRAM SEPTEMBER 7. 1989 j

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.. iXAEC1 i

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c '(1)L Review SER on RELAP5YA, explore how RELAP5YA may.be used as EM analysis method as is, with input parameters conforming to Appendix K

. requirements. If possible, identify how RELAP5YA can be modified to i conform to EM.

(2) Read SER on W method under SECY 83-472, Read W nonproprietary submittal i on SECY 83-472 method, review Regulatory Guide'1.157, and CSAU i methodology.'

(3).-Call NRClon. September 18, 1989 before noon to discuss next step.

(4') Send a summary of our understanding of this (September 7, 1989) meeting  ;

to Mort Fairtile.  !

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