ML20081B252

Ro:On 831012,standby Buses Deenergized to Allow for Operability Performance Testing of Standby Bus Breakers Per Tech Specs.Testing Caused Degraded Mode Beyond Tech Spec Limit

ML20081B252
Person / Time
Site:	Oconee
Issue date:	10/17/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
JPO-HBT-JCP, NUDOCS 8310270412
Download: ML20081B252 (2)

Text

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23  :: 21 A10 : 29 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Re: Oconee Nuclear Station Docket Nos. 50-269, -270, and -287

Dear Mr. O'Reilly:

Please find attached a Special 5-Day Report concerning the de-energization of Oconee's standby buses to allow for operability performance testing of the standby bus breakers with Keowee Unit 1 out of service. This report is sub-mitted pursuant to Oconee Nuclear Station Technical Specification 3.7.9 and describes an incident which is considered to be of no significance with respect to its effect on the health and safety of the public.

Very truly yours, C b'M Hal B. Tucker JCP/php Attachment cc: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555 INP0 Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 Mr. J. C. Bryant NRC Resident Inspector Oconee Nuclear Station Mr. John F. Suermann Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 (3Fi

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JP0/HBT/JCP

, October 17, 1983 Duke Power Company Oconee Nuclear Station Special Report De-energization of Oconee's Standby Buses to Allow for Operability Performance Testing of the Standby Bus Breakers While Keowee Unit 1 Was Out of Service On October 32, 1983, with Keowee Unit 1 out of service for planned maintenance and Keowee Unit 2 available, Lee "6C" Gas Turbine was being used to energize both Oconee 4160V Standby Buses as required by Technical Specification 3.7.4.

At 1635 hours0.0189 days <br />0.454 hours <br />0.0027 weeks <br />6.221175e-4 months <br /> Standby Bus 1 was de-energized to allow the operability test of 4160 Volt Breakers to be performed as required by Technical Specification 4.6.1.d.

Standby Bus 1 was re-energized and Standby Bus 2 was de-energized for testing its breakers. The Standby Bus 2 was re-energized at 1724 hours0.02 days <br />0.479 hours <br />0.00285 weeks <br />6.55982e-4 months <br />. The testing of the standby bus breakers causing the buses to be de-energized placed the two operating Oconee units in a degraded mode beyond that allowed by Technical Specification 3.7.4.a. This incident is reportable to the Nuclear Regulatory Commission in accordance with Technical Specification 3.7.9.

A safety evaluation was performed pursuant to Technical Specification 3.7.9 and the decision was made that allowed continuedoperation of the units since one standby bus and the Keowee underground feeder were always available during the test. Also, the breaker being tested could be closed in a matter of seconds, thereby providing power from the second standby bus as needed. The total time that Oconee had only one standby bus (either Standby Bus 1 or Standby Bus 2) energized from Lee Steam Station was 49 minutes.

At the time of the test, Lee "6C" Gas Turbine was still providing power to the Oconee standby buses via the 100 KV transmission line and in addition emergency power was available from Keowee via the underground feeder. Also available was the normal Duke Power Company transmission system to the 230 KV switchyard via at least two 230 KV transmission lines on separate towers. The probability of losing offsite power during this testing is very small; therefore, the health and safety of the public were not endangered.

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