ML19211A186

Responds to IE Bulletin 79-23, Potential Failure of Emergency Diesel Generator Field Exciter Transformer. No Connections Found Which Could Allow Flow of High Circulating Currents Exceeding Transformer Ratings

ML19211A186
Person / Time
Site:	Peach Bottom
Issue date:	10/25/1979
From:	Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
IEB-79-23, NUDOCS 7912170171
Download: ML19211A186 (2)

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[h PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 JOSEPH W. G alt.AGH ER soscrate recoucr os carantuant WNMbMM October 25, 1979 Ret Docket Nos.: 50-277 50-278 IE Bulletin 79-23 Mr. Boyce H. Grier, Director Office of Inspection & Enforcement Region I United States Nuclear Regulatorcy Commission 631 Park Avenue King of Prussia, PA 19406

Dear Mr. Grier:

This letter is in response to IE Bulletin No. 79-23, which you forwarded to us on September 12, 1979, concerning the potential failure of emergency diesel generator (EDG) field exciter transformers. Tne " Actions to be Taken by Licensees" and our responses are treated sequentially.

Action to be Taken by Licensees

1. Determine whether or not connections have been made between low KVA rated transformers and high KVA rated EDGs without adequate limitations on the flow of circulating currents.

If applicable, provide a de s c rip ti on of the corrective action being taken to address this problem.

R_e s_p_o_n_s e At Peach Bottom there are no connections between low KVA rated transformers and high KVA rated EDGs which could allow the flow of high circulating currents which could exceed transformer ratings and result in transformer damage or failure-1593 315 D122 7 ems

4 Mr., Boyce H. Grier Page 2 2 Provide a schedule for the completion of a sustained full-load operation test of the EDGs for a duration of not less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or p rovide the results of the similar long duration, full-load test which has already been c omp le t e d on the EDGs installed at your facility. The test should demonstrate full-load carrying capability for an interval of not less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of which 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> should be at a load equivalent to the continuous rating of the diesel Senerator and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at a load equivalent to the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> rating of the diesel generator. The cest should also verify that voltage and frequency requirements are maintained and that the cooling system functious within design limits.

Response

Demonstration tests performed prior to startup of the Peach Bottom units were done to prove endurance of the four emergency diesel generators. Because the testing requested in IE Bulletin 79-23 differed from that of our original testing, testing was performed recently on one of the Peach Bottom emergency diesel generators in accordance with the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> full load /2 hour emergency load rating criteria. The special testing was performed on only one Peach Bottom emergency diesel generator since all four emergency diesel generators are identical in design and installation. All systems performed within limits.

Specifically, the voltage and frequency requirements were maintained and the cooling system parameters indicated that continued full load operation would pose no problem.

Very truly yours, cc: United States Nuclear Regulatory Commission Office of Inspection and Enforcement Division of Reactor Operations Inspection Washington, DC 20555 1593 316