ML19308B093

Abnormal Occurrence AO-269/74-01:on 740129,Keowee Underground Feeder Isolated.Caused by Operator Error. Procedure Established to Require Operator to Notify Shift Supervisor Before Making Unit Inoperable

ML19308B093
Person / Time
Site:	Oconee
Issue date:	02/08/1974
From:	DUKE POWER CO.
To:
Shared Package
ML19308B089	List: ML19308B088 ML19308B093
References
NUDOCS 7912120820
Download: ML19308B093 (2)

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O DUEZ POWEE COMPANY OCONEE NUCLEAR STATION ,

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Report Date: February 8; 1974 ,.- T CG.'i.

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Occurrence Date: January 29, 1974 ,

Facility: Oconee Unit 1 Identification of Occurrence: Isolation of the Keowee Underground Feeder i Condition Prior to Occurrence: Steady-State Operation at 100% Power I Description of Occurrence:

On January 29, 1974, Oconee Unit 1 was operating at 100% full power and Oconee Unit 2 was in cold shutdown for maintenance. Both Keovee hydroelectric units were operable, but neither were operating at the time of the occurrence.

Keowee Unit 1 was connected to the 13.8 kV underground feeder, one of several sources of emergency power to Oconee. l l

During previous operation of Keowee Unit 1, vibration had been noted on speed l pickup of the Permanent Magnet Generator. At 0815, January 29, 1974, Keowee Unit 1 was made inoperable for inspection by manual initiation of the Unit 1 i generator emergency lockout. This was done at Keowee Hydro Station without '

notification to the shift supervisor at Oconee.

Initiation of the lockout caused an annuciation alarm in the Oconee Unit 1 Control Room. The Oconee control operator Lemediately contacted Keowee, determined the cause of the alarm, and then connected Keowee Unit 2 to the underground feeder. The elapsed time during which the underground feeder was connected to an inoperable Keowee unit was approximately one minute.

Regulatory Operations, Region II was verbally notified of the occurrence on January 30, 1974.

Designation of Apparent Cause of Occurrence Oconee Technical Specifications 3.7 requires that one operable Keowee unit be available to supply power through the underground feeder except for test or maintenance (not to exceed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) provided the operable Keowee hydro unit is connected to the underground feeder. The occurrence resulted because the Keowee operator failed to notify Oconee that a Keowee hydro unit would be made inoperable and the underground feader should be connected to the operable Keowee Unit.

Analysis of Occurrence Single failure analysis for the Keowee Hydro Station is presented in Table 8-6 i

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f-( t of the Oconee FSAR. A single failure analysis for the Oconee emergency electrical power systems is provided in Table 8-7. The occurrence resulted in the loss of availability of one of several power sources for approximately one minute. Because of systes redundancy and the short period of unavail-ability, it is concluded the occurrence did not affect the safe operation of the unit or the health and safety of the public.

Corrective Action:

To prevent similar occurrences, a procedure has been established which requires anyone operating the Keowee Hydro Station to notify the Oconee shift supervisor prior to making a unit inoperable. The shift supervisor will then take appropriate action to assure compliance with the Technical Specifi-cations.

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