ML18116A279

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Responds to IE Bulletin 79-11 Re Use of Westinghouse DB-50 & DB-75 Circuit Breakers.Notifies That Specified Circuit Breakers Are in Use,But W/O Overcurrent Trip Feature
ML18116A279
Person / Time
Site: Surry, North Anna  Dominion icon.png
Issue date: 07/13/1979
From: Stallings C
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 7908070743
Download: ML18116A279 (2)


Text

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VIRGINIA ELECTRiC-lANDlP.OWEH *coMPA.NY RIC:0:MOND,VIBGINIA 28261

  • q I , .. t \! 1 1 16 F-*2: 31 July 13, 1979 Mr. James P. O'Reilly, Director Serial No. 426A Office of Inspection and Enforcement PO/FHT:baw U. s.-Nuclear Regulatory Commission Docket Nos: 50-280 Region II 50-281 101 Marietta Street, Suite 3100 50-338 Atlanta, Georgia 30303 50-339 License Nos.: DPR-32 DPR-37 NPF-4 CPPR-78

Subject:

IE Bulletin 79-11

Dear Mr. O'Reilly:

In accordance with IE Bulletin 79-11, Vepco submits the following response for Surry Power Station Units 1 and 2 and North Anna Power Station Units 1 and 2.

Question 1 Determine whether circuit breakers of the above described manufacturer and type with overcurrent trip devices are in Safety Related Class IE service or in spares at your facility.

Response

The subject circuit breakers with overcurrent trip devices are not in use at Surry. The Surry reactor trip breakers are of a similar make and model, but they are used only for scram purposes. These breakers do not require the overcurrent trip feature and thus are not of concern.

A review of circuit breakers utilized at North Anna Units 1 and 2 indicates that there are no DB-75 breakers and 10 DB-50 (5 per unit) breakers, none of which are utilized in Class IE Systems. These breakers will be inspected for the described cracking during an appropriate outage.

Question 2 If the subject breakers are in service in safety-related systems: within 30 days, review the existing test data for all overcurrent trip device calibrations since plant start-up or since replacement caps were installed.

Response

The subject circuit breakers are not in use in safety-related systems at Surry Units 1 or 2 or North Anna Units 1 or 2.

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VIRGINIA ELECTRIC AND POWER COMPANY TO e

Mr. James P. O'Reilly 2 Question 3 Inspe~t all end caps in spares for cracks using at least a 3X magnifying

. glass.

Response

The Westinghouse Type DB-50 and DB-75 circuit breakers are in use at Surry but without the overcurrent trip feature described in IEB 79-11.

Therefore, the end caps are not in use or stock.

No end caps in the possession of North Anna Units 1 or 2 are for class IE circuit breakers. Spares presently in stock for the 10 (5 per unit) non-safety related DB-50 breakers will be checked for hairline cracks using at least a 3X magnifying glass prior to use.

Question 4 Review test procedures and test schedules for all safety-related circuit breakers to assure that all such breakers are tested at least each re-fueling outage to confirm overcurrent time delay protection.

Response

At Surry the 4160V safety related circuit breakers are tested each refueling outage. A periodic test is being developed to confirm the overcurrent time delay protection of 480V safety related circuit breakers.

At North Anna Units 1 and 2 all 480V and above safety-related circuit breakers are checked to confirm overcurrent time delay protection by existing preven-tive maintenance procedures at least once each refueling outage.

Very truly yours,

&. 1)7. vffa~~£,

C. M. Stallings Vice President-Power Supply and Product~on Operations