ML20134Q171

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Responds to 850722 Request for Confirmatory Response to Issues Re NUREG-0737,Item II.K.3.30 on Small Break LOCA Methods & Use of CRAFT2 Code
ML20134Q171
Person / Time
Site: Rancho Seco
Issue date: 09/03/1985
From: Rodriquez R
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Thompson H
Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.30, TASK-2.K.3.31, TASK-TM RJR-85-446, TAC-45859, NUDOCS 8509090197
Download: ML20134Q171 (2)


Text

$SMUD SACPAMENTO MUNICIPAL UTILITY DISTRICT C 6201 S Street, P.O. Box 15830. Sacramento CA 95852-1830.(916) 452-3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA RJR 85-446 September 3,1985 DIRECTOR OF NUCLEAR REACTOR REGULATION ATTENTION HUGH L THOMPSON JR DIVISION OF LICENSING U S NUCLEAR REGULATORY COMMISSION WASHINGTON DC 20555 DOCKET 50-312 RANCHO SECO NUCLEAR GENERATING STATION UNIT NO. 1 NUREG 0737 ITEM II.K.3.30, SMALL BREAK LOCA METHODS

Reference:

1.

Letter, J. F. Stolz to R. J. Rodriguez "NUREG 0737 Item II.K.3.30, Small Break loca Methods" July 22, 1985 2.

Letter. R. H. Bryan to P. Kadambi "BWOG IST Code Verification Plans" July 6, 1984 3.

Letter, F. R. Miller to P. Kadambi "IST Code Verifiction Plans" January 3, 1985 The referenced letter (Reference 1) requested a confirmatory response to issues relating to NUREG 0737 Item II.K.3.30 and the use of the CRAFT 2 code.

B&W and the B&W Owners Group endorse the conclusion in NUREG 0565 concerning the amount of noncondensible gases which could accumulate in the primary system.

The District also concurs with the B&W position regarding the radiolitic decomposition of injected water, that the source of noncondensible gas does not alter the conclusion of NUREG 0565.

The IST Program is designed to obtain data relative to SBLOCA phenomena on B&W designed PWR's.

The IST Program is not intended to provide integral test data for verification of the CRAFT 2 SBLOCA-EM computer program.

This was first stated in the B&W Owners Group Code Verifiction Plans Letter (Reference 2) and restated in the NRC Nfety Evaluation Report letter (Reference 1).

It is the intention of the B&W Owners Group to use the RELAPS/M002 code for best estimate long term transient predictions.

The RELAPS code is undergoing benchmarking to the IST test data and use of this code will form the basis for E'%%7eso90s

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" ina 04 u,

Hugh L. Thompson-RJR 85-446 September 3, 1985 I

future ATOG guidance.

It is realized that precent ATOG guidance in the area i

of SBLOCA is based on experience gained through CRAFT 2, licensing analyses.

In order to affirm the validity of present guidance in light of new best estimate codes and availability of IST data, the B&WOG has examined the merits of three alternatives to confirm the CRAFT 2 modeling capabilities.

These alternatives were presented in Reference 3 as (1) benchmark of CRAFT 2 to an OTIS test, (2) comparison between predictions of the same transient performed in a best estimate mode using CRAFT 2 and a verified RELAPS/M002 or (3) comparison between predictions of the same transient performed in an Appendix K type calculation using CRAFT 2 and a verified RELAPS/M002. The B&W Owners Group l'

validity of SBLOCA ATOG guidance.

This comparison will be performed after the plans to perform a comparison between CRAFT 2 and RELAPS/M002 to affirm the benchmarking of RELAPS/M002 to MIST data is completed. The intention of the B&W Owners Group is to perform a comparison between predictions of the same plant transient (as opposed to a MIST test transient) performed in a "best

  • stimate" mode using CRAFT 2 and a verified RELAPS/M002.

The purpose of the comparison is to demonstrate that CRAFT 2 does provide a conservative representation of SBLOCA behavior in a B&W PWR.

The District, as a member of the B&W Dwners Group, commits to participation in this program.

4 The District also commits to the use of the approved Small Break LOCA l

Evaluation Model, currently utilizing CRAFT 2, for SBLOCA analyses performed l

for Rancho Seco to resolve NUREG 0737 Item II.K.3.31, which is planned to be l

1 submitted through a B&WOG program in July 1986. The intent of the analysis to be performed to resolve NUREG 0737 Item II.K.3.31 will be to affirm the validity of previously submitted SBLOCA analyses performed with the SBLOCA-EM.

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/k R. J. R ORIGUEZ.

ASSISTANT GENERA MANAGER, l

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