ML20134P054
| ML20134P054 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/26/1985 |
| From: | Williams J TOLEDO EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0565, RTR-NUREG-0737, RTR-NUREG-565, RTR-NUREG-737, TASK-2.K.3.30, TASK-2.K.3.31, TASK-TM 1176, NUDOCS 8509060122 | |
| Download: ML20134P054 (2) | |
Text
HRE00
%ssa EDISON Docket No. 50-346 JOE VVILUAMS, JR License No. NPF-3 s-- w. w-ww Serial No. 1176 yy*l8"s August 26, 1985 Director of Nuclear Reactor Regulation Attention:
Mr. John F. Stolz Operating Reactors Branch No. 4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Stolz:
Your letter of July 18, 1985 (Log No. 1782) requested a confirmatory response to several 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 con-clusion in NUREG-0565 concerning the amount of noncondensible gases which could accumulate in the primary system. Toledo Edison 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 Verification Plan letter dated July 6, 1984 to Mr. P. Kadambi and is restated in the NRC Safety Evaluation Report attached to your letter of July 18, 1985.
It is the intention of the B&W Owners Group to use the RELAPS/ MOD 2 code for best estinate long term transient predictions. The RELAP5 code is undergoing benchmarking to the IST test data and use of this code will form the basis for future ATOG' guidance.
It is realized that present ATOG guidance in the area 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 the B&W Owners Group Code Verification Plan letter of January 3,1985 to Mr. P. Kadambi 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 REIAP5/ MOD 2 or (3) comparison between predictions of the same transient performed in an Appendix K type calculation using CRAFT 2 and a verified RELAPS/ MOD 2.
The B&W Owners Group plans to perform a comparison between CRAFT 2 and RELAP5/ MOD 2 to affirm the validity of SBLOCA ATOG guidance.
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, This comparison will be performed after the benchmarking of RELAPS/ MOD 2 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 the "best estimate" mode using CRAFT 2 and a verified RELAPS/ MOD 2.
The purpose of the comparison is to demonstrate that CRAFT 2 does provide a conservative representation of SBLOCA behavior in a B&W PWR. Toledo Edison, as a member of the B&W Owners Group, commits to participation in this program.
Toledo Edison also commits to the use of the approved Small Break LOCA Evaluation Model, currently utilizing CRAFT 2, for SBLOCA analyses performed for Davis-Besse Unit I to resolve NUREG-0737 Item II.K.3.31, which is planned to be 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.
Very truly ycurs, hM _ _ _,
JW:FYC jh b/3 cc:
DB-1 NRC Resident Inspector l
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