ML19095A566

Response to IE Bulletin No. 76-05 Concerning Westinghouse Bfd Relay Failures

ML19095A566
Person / Time
Site:	Surry
Issue date:	05/14/1976
From:	Stallings C Virginia Electric & Power Co (VEPCO)
To:	Moseley N NRC/RGN-II
References
IEB-76-005, Serial No. 028
Download: ML19095A566 (2)

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• VIRGINIA ELECTRIC .A.ND POWER COMPANY RICHMOND, VIRGINIA. 23261 May 14, 1976 Mr. Norman c. Moseley, Director Serial No. 028 Office of Inspection and Enforcement PrucM/ Alli: j lf

u. s. Nuclear Regulatory Commission Region II - Suite 818 Docket Nos. 50-280 230 Peachtree Street, Northwest 50-281 Atlanta, Georgia 30303 License Nos. DPR-32 DPR-37

Dear Mr. Moseley:

This is in response to IE Bulletin No. 76-05 concerning Westinghouse BFD relay failures. We have received the Westinghouse service letter on BFD relays and have provided Westinghouse with all of the information requested therein.

The following is a list of our actions regarding the specific require-ments of the Westinghouse service letter.

1. Normal DC bus voltage is maintained at 132 VDC. The Lead-Calcium batteries at Surry normally require no equilizing charges. This is true as long as individual cell voltages are maintained at 2.20 VDC. However, we have been in contact with the battery manufacturer's representative and have taken steps to develop an equilizing charge procedure whereby DC bus voltage is not permitted to exceed 140 VDC. This procedure will also limit equilizing charge duration to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Therefore in the unusual event that an equilizing charge is required, the BFD (DC) relays will not be affected.

2. Dropout time measure~ents have been made on all affected relayss All relays but one had dropout times less than the 30 msec per-mitted. One relay on Unit No. One (1A13) had a dropout time of 34 msec. This relay provides a close signal to the Unit No.

One air ejector discharge to containment. Relay 1A13 will be replaced at the first Unit No. One shutdown following receipt of a replacementQ The out of specification dropout time of relay 1A13 is not a problem since redundant relay 1B13 operated satis-factorily with a dropout time of 25 msec.

3. The ambient temperature of the relay racks housing BFD relays is maintained at about 84 F by the control and relay room air conditioning system. Should any of these air conditioning units fail, the station chilled water system can be used to provide the proper cooling.

e V1Rorn1A ELEcrmc AND PowEn CoMPANY To Mr. Norman c. Moseley

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4. No equilizing battery charges have been performed since the relay dropout times were measured.

5. This item is addressed in item number 1 above.

No further action is deemed necessary with regard to Westinghouse BFD relays at the Surry Power Station.

Very truly yours,

c. M. Stallings Vice President-Power Supply and Production Operations cc: NRG OFFICE OF INSPECTION AND ENFORCEMENT, Division of Reactor Inspection Programs Washington, DC 20555