ML19291C419
| ML19291C419 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/13/1979 |
| From: | Counsil W, Willie Lee NORTHEAST NUCLEAR ENERGY CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-79-23, NUDOCS 8001240377 | |
| Download: ML19291C419 (2) | |
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- 1 :: ?ll='llCl December 13, 1979 Docket No. 50-336 Mr. Boyce H. Grier, Director Region 1 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
References:
(1)
B. H. Grier letter to W. G. Counsil dated September 12, 1979, transmitting I&E Bulletin No. 79-23.
(2)
W. G. Counsil letter to B. H. Grier dated November 1, 1979.
Gentlemen:
Millstone Nuclear Power Station, Unit No. 2 I&E Bulletin No. 79-23, Potential Failure of Emergency Diesel Generator Exciter Transformer Reference (1) requested Northeast Nuclear Energy Company (NNECO) to:
(1) Determine whether elec*.rical connections between excitation power transformers and emergency diesel generators (EDG) exist without adequate limir,ticas to the flow of circulating currents.
(2) Provide a schedule for completion or the results of a long duration, sustained full-load operation test of the EDG.
In Ref erence (2), NNECO responded to the Reference (1) concerns.
In response to Item (2) of Reference (1), NNECO reported that the loading on the EDG excitation transformers was determined by measuring the transformer currents and voltages with the EDG fully loaded.
These measurements would then be compared to the transformer's nameplate rating to determine whether the component is operating within its specifications and indicate any potential for future damage or failure of the transformer.
At the time of the Ref erence (2) submittal, NNECO was awaiting information from the exciter transformer manufacturer confirming the design rating of the transformers in use at Millstone Unit No. 2.
NNECO subsequently obtained this information and provides the following supplementary response to Item (2) of Reference (1):
1795 M4-N 8 001 L 4 0 3 77
e The EDG cxcitation power transformers, consisting of three single phase trans-formers and each rated at 4.05 KVA, were tested with the EDG loaded to full load at approximately 0.8 power factor. At this loading, it was determined that the transformers were operating at a maximum 3.44 KVA or 85% of their design rating.
Based on the results of these tests, NNECO concludes that any potential for damage or failure of the EDG field exciter transformers does not exist as a consequence of the phenomena identified in Reference (1).
NNECO trusts this information satisfactorily dispositions the Reference (1)
Concerns.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY W. G. {foonsil Vice President By:
W.
F. Fee Vice President ads 1795 3t5