NSD-NRC-98-5770, Responds to NRC Ltrs Re W Requests for Withholding Info.W Withdraws AP600 Rept Entitled, Wcobra/Trac Core Makeup Tank Preliminary Validation Rept, Since Rept Was Not Required by NRC to Make Safety Determination of AP600

Responds to NRC Ltrs Re W Requests for Withholding Info.W Withdraws AP600 Rept Entitled, Wcobra/Trac Core Makeup Tank Preliminary Validation Rept, Since Rept Was Not Required by NRC to Make Safety Determination of AP600

ML20237D261
Person / Time
Site:	05200003
Issue date:	08/20/1998
From:	Mcintyre B WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NSD-NRC-98-5770, NUDOCS 9808250258
Download: ML20237D261 (2)

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Westinghouse'e Energy Systems Bm 355 Pinsburgh Pennsylvania 15230~0355 Electric Corporation DCP/NRC1427 NSD-NRC-98-5770 Docket No.: 52-003 l

August 20,1998 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: T. R. Quay

SUBJECT:

RESPONSE TO NRC LETTERS CONCERNING REQUESTS FOR WITHHOLDING INFORMATION l

Reference:

1. Letter, Huffman to McIntyre, " Request for withholding information from public l disclosure of Westinghouse report: WCOBRA/ TRAC Core Makeup Tank Preliminary Validation Report," dated July 17,1998.

Dear Mr. Quay:

Reference i sets forth the NRC assessment of the Westinghouse claim for treatment of proprietary information submitted by Westinghouse in letter NTD-NRC-95-4411 dated February 28,1995, which

letter provided an AP600 report titled "_WCOBRA/lRAC Core Makeup Tank Preliminary Validation i Report." The staff was not able to locate a final version of the AP600 WCOBRA/ TRAC Core _

Makeup Tank Validation Report. The NRC assessment was that since the material submitted in the Westinghouse letter of February 28,1995, was not bracketed and a non-proprietary version of the report was not located, the staff could not complete its proprietary determination. The staff requested l . Westinghouse to review its proprietary claim and to notify the staff of what portions, if any, are still considered proprietary.

l L Westinghouse has reviewed the material submitted on February 28,1995, and still considers portions of the material as proprietary. However, Westinghouse requests withdrawal of the AP600 report titled "WCOBRA/ TRAC Core Makeup Tank Preliminary Validation Report" since the report was not required by the staff to make a safety determination of the AP600 as part of the design certification review.

l Westinghouse submitted this report to support validation of theWCOBRA/ TRAC computer code for

. small break loss of cooling accident (SBLOCA) analysis of AP600 transients. However, kg

. Westinghouse did not use the WCOBRA/ TRAC code in the AP600 SSAR for SBLOCA analysis, where the performance of the core makeup tanks (CMTs) are an important phenomena.

WCOBRA/ TRAC is only used to analyze AP600 transients resulting from a large break loss of

_. cooling accident (LBLOCA) and during the long term cooling (LTC) portion of a transient. _

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DCP/NRCl427 NSD-NRC-98-5770 August 20,1998 In the case of a LBLOCA, the CMT performance is not important, since the CMTs are inactive during the analyzed portion of the transient. During the portion of the transient of interest, prior to the occurrence of the peak clad temper-1..

. the CMTs remain full and do not drain. The accumulators provide the necessary cooling water since the plant depressurizes so rapidly. Therefore, validation of the CMT performance using WCOBRA/ TRAC is not necessary for a LBLOCA.

During the LTC portion of a transient, as a result of either a SBLOCA or LBLOCA, the CMT performance is of little importance. The CMT is nearly empty, having drained its inventory into the reactor vessel prior to the start of the LTC transient. The IRWST and recirculation from the lower containment compartments provide the necessary cooling water during LTC. Therefore, validation of the CMT performance using WCOBRA/ TRAC is not necessary for LTC.

Since the performance of the CMT is not modeled for any transients analyzed in the AP600 SSAR with the WCOBRA/ TRAC computer code, the "WCOBRA/ TRAC Core Makeup Tank Preliminary

- Validation Report" is not required for the staff to make a safety determination and Westinghouse requests the report be withdrawn.

A (('

Brian A. McIntyre Manager

. Advanced Plant Safety and Licensing jml ec: J. W. Roe - NRC/NRR/DRPM J. M. Sebrosky - NRC/NRR/DRPM W. C. Iluffman - NRC/NRR/DRPM

11. A. Sepp - Westinghouse 1

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