ML20090E995

Discusses Interpretation of 10CFR50.46 & App K by NRC & Impact on CP Licensing Proceedings.Recommends That Commission Provide Guidance to NRC

ML20090E995
Person / Time
Site:	Three Mile Island
Issue date:	04/01/1977
From:	Sherwood G GENERAL ELECTRIC CO.
To:	Rowden M NRC COMMISSION (OCM)
Shared Package
ML20090E978	List: ML20090E995
References
TASK-*, TASK-07, TASK-7, TASK-GB GPU-2206, MFN-127-77, NUDOCS 8307020222
Download: ML20090E995 (5)

Text

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.M l Q." G EN ER Al. h ELECTRIC NUCLEAR ENERGY SYSTEMS DIVISION GENERAL ELECTRIC COf.tPANY.175 CURTNER AVCNUE. sat: JOSE. CALIFORNIA 95125 ,

Phono (406) 2913000 TWX No. 010-338-0116 MFN-127-77 I

JL April 1, 19.77 CC $. fy,d

}.} hob' fG The Honorable Marcus A. Rowden af 0 4-'

Chairman, U.S. Nuclear Regulatory Commission Wa,shington, D. 9 20555

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SUBJECT:

INTERPRETATION OF 10 CFR I 50. 46 AND APPENDIX K ,p gl@

Dear % Ro,

wden:

' We wish to- communicate to you General Electric's experience with the overly conservative interpretationmf 10 CFR 550.46 and Appen-dix K by the- NRC St'aff and its impact on construction permit 'licens-ing proce~edings. We do not believe that the original intent in

, draf ting 10 CFR 5 50. 46 and Appendix K was to virtually stop project

, licensing whenever amendments to loss-of-coolant-accident (LOCA)

O. evaluation models were proposed or made. However, we have found -

this to be the case in recent reviews of LOCA computer code QA audits. Policy, guidance by -the Commission -is necessary in order to amelloratie the restrictive climate -under_ which thd Appendiff'R-licensing, actions are conducted. This letter reviews tur recent l experience and' reqdests _that- the Commission provide guidance to j- the NRC 5taff on"this subject. - ;- =- -

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Applicants',' vendors and the NRCL have had over two years of (experi-ence with LOCA analysis since the ECCS rule making was completed.

Although LOCA evaluation models with their numerous computer codes and analytical models were approved following the promulgation of l

the ECCS rules, we have found that the evaluation models , require l periodic audits in order to check the literally hundreds of para-l meters and inp*uts connected with each LOCA analysis. These audits l are to guarantee conformance of evaluation models and inputs with -

the physical and nuclear properties of plants being analyzed.

Pursuant to Paragraph 1.b. of Part II of Appendix K, it is, of course, necessary to amend evaluation models to reflect signifi-

. cant changes that result fn calculated fuel-clad temperature s l different by more than 20 F from the temperature calculated in

! a previously accepted model. We have found in practice that the Staff believes it necessary to interrupt ongoing construction permit licensing proceedings whenever significant or potentially CON: K A.

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. . G EN ER AL () ELECTRIC 4/1/77 Rowden

. The Honorable Marcus A. l

()' These inter-significant evaluation model changes are identified.on (1) final analysis ruptions can result even though the change: 0 (2) results in a does not result in a temperature exceeding 20 F, lowering of the calculated peak-clad temperature, or (3) criterion. The interruption can continue until corrections are incorporated in the LOCA model, a new acceptable eval new model are run.

This Staff practice has recently delayed construction In these specific permitsitua-licensing and hearings on two projects.tions, both that General in any event Electric a the resultant temperature change would be minor, the calculated result would certainly not approach any of the licensing limits set forth in 10 CFR 550.46, and that the con-clusions regarding issuance .of construction permits would not be

- altered. 2,.__, __

This Staff 5'osi' tion . appears to follow'from-its belief that it is ~

necessary, prior to issuing a construction permit, reflecting all -to have an potentially 0 informa-approved evaluation model on file,(i.e., having an effect greater than 20 F) signi'ficant While General O- tion andconcurs Electric detailedwith calculations revising with the LOCAthat model.

models to reflect signifi-cant new information, it believes that a model revision can be accomplished wihhou't_ the frantic effort on the part of both ,

General Electric .and the 'NRC Staff- with the concurrent, p_r_oject Ceruainly disruption _that has accompanied these recent efforts.if the ne in all probability result in" calculations exceeding -regulatory limits, prompt acti_on may be dictated for operating licensk apoli-caticns.

But to date the new information has generally been pre-liminary and has not resulted in violation of regulatory limits; however, it has produced significant disruption of projects in the construction permit phase of licensing.

General Electric believes that these matters can be handled on an orderly basis in full compliance with all regulatory requirements.

In construction permit proceedings, a commitment by the applicant to meet all ECCS criteria requirements before approval of the operating license should be sufficient to permit continuation

- of licensing where:

1. The applicant has demonstrated conformance to ECCS criteria using the previously or currently approved

' evaluation model.

2. The NRC Staff has reached a reasonable judgment that i

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GENER AL (3 ELECTRIC The Honorable Marcus A. Fbwden 4/1/77 either:

a. The evaluation model change will not result in calculated temperatures, exceeding regulatory criteria, or -

b. There is reasonable assurance that other changes to the evaluation model or proposed equipment modifications (i.e., offsetting benefits) will result in the evaluation model change with calculated temperatures

. satisfying regulatory criteria.

3. An amendment of the evaluation model, or performance of calculations in accordance with a newly amended evalua-tion model, would interrupt or delay licensing proceed-ings.

Commission regulations [10 CFR 5 50. 35 (a) (2) ] . provide that a con-struction permit may be issued when all required technical infor-mation has not been supplied if such information wi'11 be supplied in the final safety analysis report and there is reasonable assur-ance that any safety questions will be satisfactorily resolved O' trior to completion of construction. . .

A second area of concern is the Staff determination that LOCA calculations must be repeated for operating plants each time an evaluation model is amended. As a result, expensive and time _ n rr consuming calculations are required, although the approximate - - --

magnitude of the result is already known and it is within regu-latory limits (22000F). Individual LOCA calculations cost about

$50,000, and with 35 operating BWR plants, the ovarall cost and time expended by General Electric and its customers becomes unreasonable. We would recommend that the Staff be permitted to exercise discretion in such cases to permit delay in performance of recalculations using new models until regulatory limits are approached. When offsetting changes are under review and likely to be approved, delay in calculations should be permitted until such changes can be taken into account.

General Electric requests that the Commission review the language of 10 CFR 5 50 and provide policy guidance to the NRC Staff in the areas discussed above. In particular, we recommend that this guidance provide the Staff with an opportunity for technical judg-ment which can permit the continuation of construction permit activities, with approved models to be required before operating licenses are issued. With regard to operating licenses, it would O appear that recalculations are not required if the technical staff does not believe that model changes involved will result 3

V05390

,. GENERAL @ ELECTRIC

, The Honorable Marcus A. Rowden 4/1/77 in calculated peak-clad temperature in excess of 2200 F.

We would be pleased to discuss any of these details more fully with you and look forward to your response on this issue.

. Respectfully submitted,

,. un G enn G. Sherwood, Manager Safety & Licensing Mail Code 676; Ext. 5040 es .

cc: R. S. Boyd -

R. E. Heineman B. C. Rusche - - ~

V. Stello, Jr. .

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I bec: R. H. Beaton A. P. Bray

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A. A. Kerr

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S., , Levy J. F. O'Mara J. K. Restrick l G. J. Stathakis

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BWRPD S taf f S&L Staff R. Lowens tein J. E. Ward (AIF) l O

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. THE BABCOCK & WILCOX COMPANY -

POWER GENERATION GROUP To NSE D4 DI l DISTRIBUTION

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H. A. BAILEY - LICENSING (2678) , ,

,,3 . 3,3 Cust. F File No.

or Ref. 20A3 Subj. . Date STANDARD PROBLEM - ECCS MARCH 2, 1977 l m . i .. .. . ., . .... . . . .. .

DISTRIBUTION - - -

B. E. Bingham 1- ~ F. J..JLevandoski - ,-

J. J. Cudlin M. I. Meerbaum '-

N= F. Norman R. C. Jones  ;-N. H. Shah Increased emphasis is being put on ECCS Standard Problems by the NRC now as evidenced by this latest letter (attached) from D. F. Ross. This emphasis is partly due to the LOFT (non-nuclear) experiment which will be the next Standard Problem (!7) and will be performed about May, 1977. -

A draft document, " Standard Problem Program" (attached) includes the future role of the Standard Problem Program in licensing.

The NRC has requested comments on this document at the next i

Standard Problem meeting on March 17 and 18, 1977. Your comments are requested by March 14. .

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