ML20135E447

Informs of Status of Util Responses to NRC RAI Concerning Methodology Util Will Use to Reanalyze Containment Pressure Response Following LOCA

ML20135E447
Person / Time
Site:	Maine Yankee
Issue date:	12/04/1996
From:	Frizzle C Maine Yankee
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CDF-96-199, MN-96-182, TAC-M94835, NUDOCS 9612110276
Download: ML20135E447 (2)

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MaineYankee HE t.l A BL E f t E C T RICIT Y blNC E 19 7 2 1

329 Bath Road Charles D. Frizzle Brunswick Maine 04011 President and Chief Executive Officer (20n na-41oo l December 4,1996

! MN-96-182 CDF-96-199 l l l

UNITED STATES NUCLEAR REGULATORY COMMISSION l l Attention: Document Control Desk Washington, DC 20555

References:

(a) License No. DPR-36 (Docket No. 50-309)

(b) MY Letter to USNRC dated April 12,1996 (MN-96-048) - Integrated Containment j Analysis - Methods Summary and Identification of Differences from SRP {

(c) USNRC Letter to Maine Yankee dated May~31,1996 -' Maine Yankee Containment b Reanalysis (TA~C NO. M94835) " ' ' ' ' ^~ -

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'(d) MY Letter to USNRC datedJul 23/1996 (MN-96-102)iResponse to RAIIntegrated Containment Analysis 4 l

(e) MY Letter to USNRC dated October 3,1996 (MN-96-144) - Second Response to RAI -

' Integrated Containment Reanalysis Methodology l

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Subject:

RAI - Integrated Containment Reanalysis Methodology l

We submitted a summary of the methodology we plan to use to reanalyze the contr.inment pressure response l following a LOCA in Reference (b). Your staff issued a request for additional information (RAI) on our

! proposed methodology in Reference (c). We provided responses to all but two (2) of the thirteen (13) questions

, posed in your RAI in References (d) and (e). Unfortunately, we continue to have difficulty completing the I

responses to the remaining questions (Questions 1 and 6) and require a revision to our schedule. This letter i provides the status of our responses to these two questions and a revised schedule for responding to them.

Please note that the completion date for the containment reanalysis remains unchanged.

l In response to your Question 6 and in keeping with our original plan, Reference (b), we have been assessing steam generator heat transfer in Yankee Atomic Electric Company's (YAEC's) version of RELAPS/ MOD 3.

This has been done by comparing RELAPS/ MOD 3 predictions to the measurement results of two tests performed in the FLECIIT-SEASET Steam Generator Separate Effects Test Facility. Our comparison of q i

predictions to measurements for one of the tests was good, llowever, our comparison to the other test data l infers that a modification to the methodology may be necessary to ensure a conservative bias in steam generator '

heat transfer. Although we have reviewed the heat transfer models in our version of RELAPS/ MOD 3 and made minor modifications to these models, those modifications have not resulted in substantial improvement in the comparisons to data for the latter test. We are currently performing a review of the test data and our model of the facility before making further changes to the code.

j Our response to Question 1, Benchmark of Analysis Methods, is on hold pending the outcome of our )

l assessment of steam generator heat transfer. Our response to this question consists of documenting a

comparison of our methodology with methodology that has been approved by NRC for this application. We have completed a calculation of mass and energy discharged for a double-ended break in the hot leg . These results are in close agreement with the results obtained using the approved methodology. We have also /

compared the response of our GOTIIIC model of the containment to the response predicted using the approved 4 methodology. This comparison was also good. We have not completed our comparison of the cold leg pump suction break since it will be strongly affected by steam generator heat transfer modeling, which may change,

., depending on our response to Question 6.

J 9612110276 961204 PDR ADOCK 05000309 p PDR .

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MaineYimkee L

UNITED STATES NUCLEAR REGULATORY COMMISSION MN-96-182 Attention: Document Control Desk Page 2 Our responses to Questions land 6 have taken longer than anticipated and will require a revision to our schedule for responding to these two questions. Our revised schedule, which is provided below, reflects our estimate of the effort necessary to perform additional assessment of steam generator heat transfer. We are hopeful that our schedule for completion of Tasks 3 and 4 will not be impacted. Ilowever, because the resolution of the discrepancy may involve unanticipated code development, the completion date is uncertain.

We will keep you infarmed of our progress and any changes to our scheduled completion dates.

Schedule for Completing the Integrated Containment Reanalysis Task l Description Current Actual / Revised i Submit Methods Summary and Identification of 04/12/96 NA Differences from SRP 2 NRC Review of Methods Summary and 05/31/96 NA Differences from SRP 2a Submit Answers to Remaining RAI Questions 12/01/96 01/30/97 3 Submit Methods and Sample Calculation 01/30/97 01/30/97 4 Submit Analysis Results and Associated Proposed 05/01/97 05/01/97 Technical Specifications We trust that the information in this letter is satisfactory. Please contact me if you have any questions.

Very truly yours,

,7 c/

< &,7 Charles D. Frizzle President and Chief Executive Officer Enclosure l l

c: Mr. II. J. Miller Mr. D. II. Dorman Mr. J. T. Yerokun Mr. Clough Toppan l Mr. Patrick J. Dostie  !

Mr. Uldis Vanags l Donald Zillman, Esq.

Lawrence J. Chandler, Esq.,

Assistant General Counsel for IIcarings and Enforcement STATE OF M AINE Then personally appeared before me, C. D. Frizzle, who being duly sworn did state that he is President and Chief Executive Officer of Maine Yankee Atomic Power Company, that he is duly authorized to execute i and file the foregoing response in the name and on behalf of Maine Yankee Atomic Power Company, and that the statements therein are true to the best of his knowledge and belief.

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. ;A r, w Y /h I h$h w Notary Public l

l BARBARA J. PADAVAHA ,

men Mas amm W udw I