ML20214M703

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Discusses Adequacy of Suroweic Line to Carry Plant Emergency Loads,Based on Jul 1986 Incident.Evaluation Shows That Voltage on in-plant Buses within Acceptable Limits at All Times.Detailed Analysis Expected by Early Jul
ML20214M703
Person / Time
Site: Maine Yankee
Issue date: 05/27/1987
From: Whittier G
Maine Yankee
To: Nerses V
Office of Nuclear Reactor Regulation
References
GDW-87-130, MN-87-64, NUDOCS 8706010406
Download: ML20214M703 (2)


Text

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MAIRE 9ARHEE 'ATOMICPOWERCOMPARSe

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May 27, 1987 HN-87-64 GDH-87-130 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.

20555 Attention:

Mr. Victor Nerses, Acting Director PHR Project Directorate 1-3 Division of Licensing

References:

(a) License No. DPR-36 (Docket No. 50-309)

(b) USNRC Letter to HYAPCo dated April 23, 1987, Safety Evaluation Concerning the Adequacy of Offsite Power Systems

Subject:

Offsite Power Gentlemen:

This letter is in response to Reference (b) which expressed concern about the adequacy of the Surowelc line to carry plant emergency loads.

This concern was apparently based on a low voltage incident during a plant startup which occurred in July of 1986. Maine Yankee has evaluated the incident in question and has concluded that the voltage on in-plant buses was at all times within acceptable Ilmits. Our evaluation has also shown that emergency loads could have been provided while maintaining adequate voltage on in-plant busses. He have concluded, based on this evaluation, that the Surowelc line is adequate to provide plant emergency loads.

He are currently performing a more detailed analysis of the Suroweic line.

He expect the analysis to be completed in early July.

He will forward the results to you as soon as they are available.

He expect that the analysis of the Surowelc line will confirm that the Surowelc line is adequate to carry plant emergency loads although the safety margin during portods of heavy use may be small. He have concluded that the Surowelc line may still be relled on to meet Technical Specification requirements for off site power during normal plant operations. However, during plant startup, we will not rely on the Surowelc line to meet technical Specification requirements for off site power, pending the completion of the on-going analysis and any upgrades which may be warranted.

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MAINE Y ANKEE ATOMIC POWE2 COMPANY United States Nuclear Regulatory Commission Page Two Attention: Mr. Victor Nerses, Acting Director MN-87-64 Please contact me if you should have any questions.

Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY G. D. Whittier, Manager Nuclear Engineering and Licensing GON/bjp cc: Mr. H1111am T. Russell Mr. Pat Sears Mr. Cornelius F. Holden 8729L-G0H