ML19329B930

RO NP-33-77-09:on 770524,during Control Room Emergency Ventilation Sys Refueling Damper Strings HV-5361A & HV-5362B,required 10 Response Time.Caused by Stroke String Response Time Exceeding Allowable Level

ML19329B930
Person / Time
Site:	Davis Besse
Issue date:	06/24/1977
From:	Batch S, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19329B924	List: ML19329B923 ML19329B930
References
NUDOCS 8002060915
Download: ML19329B930 (2)

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DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-9 DATE OF EVENT: May 24, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Control Room ventilation (SFAS actuated portion) damper string did not meet required response time as per Technical Specification 3/4.3.2.1 placing unit in Action Statement 10.

Conditions Prior to Occurrence: The plant was in Mode 5. Power: MWT-0, MWE-0 Description of Occurrence: During the scheduled execution of Surveillance Test ST 5076.03,- Control Room Emergency Ventilation System Refueling Test, it was determined that two of the tested damper strings (HV 5361A and HV 53623) failed to meet their required 10 cecond response ti=es.

Designation of Apparent Cause of Occurrence: The stroke timas of HV 5361A and I

~%}iV 5362B in combination with the string response time exceeded the allowable s

3tring response ~ time of 10 seconds.

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Analysis of Occurrence: Action Statement 10 of Technical Specification 3/4.3.2.1 requires the plant to be in cold shutdown within 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> if the " inoperable functional unit" is not restored to service. Since the plant was already in Mode 5 (cold shutdown) at this time and ST 5076.03 Acceptance Criteria were satis-fied (response time d- 10 seconds) within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, no threat resulted to the health and safety of the public or station personnel.

Corrective Action: ST 5076.03 was re-run on May 25, 1977 and Acceptance Criteria was met. HV 3361A and HV 5362B were repeatedly stroked. Successive response times met Acceptance Criteria and satisfied . Technical Specification 3/4.3.2.1.

l Failure Data: No previous similar events have occurred.

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