ML20149M994
| ML20149M994 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 02/12/1988 |
| From: | Whittier G Maine Yankee |
| To: | Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 9373L-SDE, GDW-88-06, GDW-88-6, MN-88-03, MN-88-3, NUDOCS 8802290359 | |
| Download: ML20149M994 (1) | |
Text
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MaineYankee REUABLE ELECTRICITY FOR MAINE SINCE 1972 EDISON DRIVE. AUGUSTA. MAINE 04330. (207) 623 3521 February 12, 1988 HN-88-03 GDH-88-06 Region I United States Nuclear Regulatory Commission 475 Allendale Road King'of Prussia, Pennsylvania 19406 Attention; Mr. William T. Russell, Regional Administrator
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) MYAPCo Letter to USNRC dated September 22, 1987 (MN-87-105)
(c) USHRC Letter to HYAPCo dated August 21, 1987, Inspection Report 87-12
Subject:
Breaker Coordination Study Gentlemen:
Maine Yankee committed, in Reference (b), to provide you with the results of our investigation of circuit breaker coordination. Our investigation has identified some conditions where coordination between molded case circuit breakers in distribution panels for safety-related equipment could be improved to enhance safety.
Since the redundant safety-related components are generally powered from separate and independent sources, we have concluded that the probability of losing both components due to inadequate coordination is small. Consequently, no immediate safety problem exists.
The NRC audit team similarly found that breaker coordination problems did not appear to be a s'.gnificant safety concern, i
To improve the coordination between circuit breakers, panel feeder breakers in panels DP/IAC, DP/lA and DP/lB will be replaced with new breakers by the erd of the 1988 refueling outage.
Four panels (Cab P Crb BU, DP/DG-1A, DP/DG-lb) require an engineering design change to improve coordination; these changes will be scheduled for implementation by the end of the refueling outage following Cycle 11 operation.
Please contact us if you have any questions.
l l
Very truly yours, l
MAINE YANKEE m22;ggggi02go,y
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P G. D. Whittier, Manager Nuclear Engineering and Licensing GDH/bjp 1
i cc: Mr. Richard H. Nessman Mr. Pat Sears Mr. Cornelius F. Holden 9
9373L-SDE T_.Cr o \\
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