ML19282A638

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Suppl 790216 Final Rept on Correction of Calculation Method for Axial Power Distribution Monitoring Sys.Feels Proposed Administrative Procedures Satisfactorily Resolve Nonconservatism Problems
ML19282A638
Person / Time
Site: North Anna Dominion icon.png
Issue date: 02/27/1979
From: Brown S
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
575C, NUDOCS 7903050246
Download: ML19282A638 (2)


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February 27, 1979 Mr. James P. O'Reilly, Director Serial No. 575C Office of Inspection & Enforcement PSESC/LCK:adw:me U. S. Nuclear Regulatory Comission Region II Docket No. 50-339 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

Ir. ecordance with 10CFR50.55(e), the NRC Region II, was notified on October 6, 1978 that the North Anna Unit 2 Axial Power Distribution Monitoring System (APDMS) provided by Westinghouse Electric Corporation con-tained a non-conservatism capable of causing an error in the calculation of LOCA peaking factor shape limits. This error was caused by a calculational round off which increased the set point above the desired value by as much as 1.1%.

In our previous letter of February 16, 1979, Serial No. 575B, we pre-sented our final report on this concern stating that the deficiency would be corrected by implementing administrative procedtres which lower the input values used by APDMS by 1.5% to accommodate the non-censervatism. We stated that the procedures were currently being used at North Anna Unit 1. Following the transmittal of this letter, your Mr. M. S. Kidd requested this supplemental letter concerning the APDMS matter.

It is Vepco's opinion that the proposed administrative procedures in our letter of February 16, 1979 satisfactorily resolve all potential safety im-plications and as such, the APDMS round-off non-conservatism deficiency is corrected. However, the operations staff at our North Anna pcuer station is currently considering the possibility of alternate methods of lowering the add-itional penalty of 1.5% on APDMS measured input values. The primary methods now being considered consist of either various Technical Specification revisions or possible APDMS hardware / software modifications.

In any case, the fact remains that all possible safety implications associated with the APDMS K(z) limit setooint non-conservatism have been adequately corrected and thus no longer pose a concern.

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Mr. James P. O'Reilly 2 This letter is to be considered an addition to our final report on this item and no further correspondence is anticipated.

Very tr ly yours, Sam .. lifrown, Jr.

Senior Vice President Power Station Engineering and Construction

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c: Mr. John G. 6vis, Acting Director Office of Inspection & Enforcement Mr. Harold R. Denton, Director Office of fluclear Reactor Regulation i