ML19308A873

Unusual Event:On 730601,audit Revealed Periodic Test Not Performed on External Grid Trouble Protective Sys Logic Misunderstanding in Test Responsibility Assignment.Test Performed 730610 & Test Assignment Defined

ML19308A873
Person / Time
Site:	Oconee
Issue date:	07/10/1973
From:	DUKE POWER CO.
To:
Shared Package
ML19308A865	List: ML19308A864 ML19308A868 ML19308A873
References
NUDOCS 7912120661
Download: ML19308A873 (2)

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DUKE POWER COMPANY OCONEE NUCLEAR STATION - UNIT 1 UNUSUAL EVENT REPORT FAILURE TO PEBrtRM A PERIODIC TEST Introduction Oconee Unit 1 Technical Specification 4.6.4 requires that the External Grid Trouble Protective System logic shall be tested quarterly to demonstrate its ability to provide an isolated power path between Keowee and Oconee. On June 1, 1973, an audit revealed that this periodic test had not been com-pleted as scheduled. Technical Specification 1.9 defines an unusual event as any observed inadequacy in the implementation of administrative or pro-cedural controls during the operation of the facility which could signifi-cantly affect the safety of operation. Failure to perform the above periodic tests is classified as an unusual event and is reported pursuant to Technical Specification 6.6.2.1.

l Description of the Incident On June 1, 1973, it was discovered during an audit of the Performance Group's periodic tests for Unit 1 that PT/0/A/610/2, " External Grid Trouble Protective l System Logie," which was scheduled to be completed on April 10, 1973 had not been done. This test is a quarterly periodic test as required by Section l 4.6.4 of the Technical Specifications. An investigation revealed that the last time the test was performed was October 27, 1971 under TP/1/A/610/2A, 2B, and 3B. The test was not performed as scheduled due to a misunderstanding it assignment of test responsibility.

Corrective Action PT/0/A/610/2, " External Grid Trouble Protective System Logic,"was performed on June 10, 1973. The assignment of the responsibility for completing this periodic test has been defined, and failure to perform the test should not recur.

Safety Analysis The External Grid Protective System is provided to isolate the 230 kV switching station on failure of the external transmission network. Should the system

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fail to operate, providing a power source from ,Keowee to Oconee via the 230 kV switchyard during a loss of the external network, power to Engineered Safe-guards systems would be provided by redundant emergency source of power via the 13.8 kV underground feeder from Keowee. Furthermore, redundant channels for detecting both undervoltage and underfrequency conditions are provided to increase the reliability of transfer of Oconee off of the External Grid Sfstem.

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