ML19327B013

Forwards Rept 86-1176204-01, Davis-Besse Unit 1 Cycle 7 LOCA Limits. Rept Details Reanalysis of LOCA Max Linear Heat Rate for All Elevations for Cycle 7

ML19327B013
Person / Time
Site:	Davis Besse
Issue date:	10/16/1989
From:	Shelton D TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML19327B014	List: ML19327B013 ML19327B016
References
1720, NUDOCS 8910240191
Download: ML19327B013 (2)

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TOLEDO EDISON i ,

A Certnr Erwrgy Conomy DONAU) C. SHELTON Docket Number 50-346 s',@7" License Number NPF-3

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Serial Number 1720 b october 16, 1989 s, '

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U United States Nuclear Rcgulatory Commission Document Control Desk Vashington, D. C. 20555

Subject:

Reanalysis of LOCA Maximum Linear Heat Rates for Davis-Besse Nuclear Power Station Cycle 7 Operations Gentlemen License Amendment Number 123 (Log Number 2719) which approved the Davis-Besse

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Nuclear Power Station (DBNPS) Cycle 6 Reload Report by issuing associated

. revised technical specifications, was issued by the NRC on October 3, 1988.

The NRC Safety Evaluation issued with Amendment Number 123 required that

' Toledo Edison provide Cycle 6 confirmatory calculations for the LOCA maximum linear heat rates at the 4, 8, and 10 foot core elevations within six months after the start of Cycle 6.' The Cycle 6 calculations for the 2 and 6 foot elevations were provided in the Licence Amendment Request for the Cycle 6

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' Reload Report (Serial Number 1516, dated May 18, 1988). Toledo Edison submitted a proposed alternative (Serial Number 1606, dated December 2, 1988) ,

to perform a complete reanalysis of LOCA maximum linear heat rates for all elevations for Cycle 7 in lieu of performing the calculation of selected core elevations for Cycle 6. The NRC approved this proposed alternative in a y letter dated January 27, 1989 (Log Number 2816). The purpose of this letter. l is to provide the NRC with the reanalysis of LOCA maximum linear heat rates L for all: elevations for Cycle 7.

l The attached Babcock and V11cox (B&V) report (86-1176204-01) details the reanalysis for the DBNPS. The reanalysis was performed by B&V using TACO 2 as  !

part of the LOCA Evaluation Model. The report discusses in detail the new LOCA limits as compared to the interim LOCA limits adopted in 1986 and the BAV-10105, Revision 1 (1975) LOCA limits at different core heights and how the  !

new limits are affected by changes in the input assumptions. As discussed in I the report, the reductions in the revised LOCA limits at 4, 6 and 8 foot elevations are primarily attributed to the use of t'e BVC critical heat flux

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THE TOLEDO EDl5'ON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652 B910240191 891016

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. Docket Number 50-346 Lic:nso Nu ber NPF-3

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. S:rici Number 1720 Page 2 correlation and/or FLECSET reflood heat transfer coefficients. The BVC correlation and FLECSET heat transfer coefficients were not used for the current operating cycle (Cycle 6) and, therefore, the results provided in the report do not adversely impact the operating limits for Cycle 6.

The NRC letter dated January 27, 1989 (Log Number 2816) required Toledo Edison to' submit the attached reanalysis of LOCA maximum linear heat rates by  !

September 15, 1989. On September 9, 1989 B&V experienced a computer software

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failure while running similar calculations for anothet' utility. Due to this failure, the DBNPS report was placed on hold while B6V personnel investigated the failure. On September 12, 1989, B&W determined that the failure was due to a data entry error and did not impact the DBNPS calculations. However, B&W personnel stated that there vould be a delay in the issuance of the report to Toledo Edison as result of their effort to document and correct the failure.

On September 12, 1989, Toledo Edison notified the NRC of the B&W delay and a new submittal date of October 16, 1989 was established. {

I Should further information be required, please contact Mr. R. V. Schrauder, Nuclear Licensing Manager, at (419; 249-2366.

Very truly yours, Y

Attachment L

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cc P. Byron, DB-1 NRC Senior Resident Inspector A. B. Davis, Regional Administrator, NRC Region III l T. V. Vambach, NRC/NRR DB-1 Senior Project Manager '

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