ML19326A557

RO NP-33-77-78:on 770727,power Indication Light for Containment Vacuum Relief Valve Cv 5074 Found Off.Caused by Local Remote Switch Found in Local Position.Valve Returned to Svc

ML19326A557
Person / Time
Site:	Davis Besse
Issue date:	08/19/1977
From:	Lingenfelter J, Vallade S TOLEDO EDISON CO.
To:
Shared Package
ML19326A539	List: ML19326A538 ML19326A557
References
NUDOCS 8002040724
Download: ML19326A557 (2)

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@la,Control Room Operator observed that a ooygr._ipMeneinn 14ehe bnw r'an e s 4 n- _I t<e g l ment Vacuum Relief Valve CV 5074 was off. The valve was belikved inopera-;

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CAust OtsCntPilow g [ A local /rer,ote switch, the function of which is to remove Control Room ld l' power and, indication for the valve in the event of loss of Control Room ]

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(F 1 , ::- TOLEDO EDISON COMPANY

- DAVI 3 ESSE UNIT ONE NUCLEAR.F0WER . TION

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- SUPPLEMENTAL INFORMATiON FOR LER NP-33-77-38 1

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DATE OF EVENT: July 27; 1977 ',

FACILITY: Davis-Besse Unit 1 i IDENTIFICATION OF OCCURRENCE: Containment Isolation Valve CV 5074 was inoperable.

l Conditions Prior to Occurrence: .The plant was in Mode 3, with Power (MWT) = 0 and Load (MWE) = 0.

Description of Occurrence: On July 27,~1977 at 1638 hours0.019 days <br />0.455 hours <br />0.00271 weeks <br />6.23259e-4 months <br />, an operator in the Control l Room observed that a power indication light for Containment Vacuum Relief Valve,

) - CV 5074,was off. Investigation revealed that the valve was open, however, and the l breaker closed. Electricians who checked the control circuit in the Control Room ~

found no problem. i 1

Since CV 5074 was believed to have been inoperable, power was removed to the valve (making it inoperable). CV 5074 was closed at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on July 27, 1977. This was done in compliance with Action' Statement (b) of Technical Specification 3.6.3.1.

Designation of Apparent Cause of Occurrence: The local / remote switch, the function of which is to remove control power and indication from the Control Room for the valve in the event of loss of Control Room operability, was found in the " local" posi-i tion. The exact reason that the switch was in the " local" position is not known.

Since construction personnel were working in the area with scaffolding (at the level 1 of the local / remote switches) at the time of the occurrence, it is suspected that they inadvertently repositioned CV 5074 from " remote" to " local".

Since power indication to the Control Room was lost, the valve was believed inopera-ble, and power to the valve deliberately removed as required by the Action Statement.

Analysis of Occurrence: There was no danger to the health and safety of the public or station personnel. From 1638 hours0.019 days <br />0.455 hours <br />0.00271 weeks <br />6.23259e-4 months <br /> to 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on July 27, 1977, the Safety

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Features Actuation System'would have been able to close CV 5074, and thus, ensure Containment integrity,if it was needed. At 1806 hours0.0209 days <br />0.502 hours <br />0.00299 weeks <br />6.87183e-4 months <br />, the valve was closed and power removed, returning Containment integrity.

I Corrective Action: CV 5074 was returned to service at 0800 houts on July 28, 1977, removing the station from Action Statement (b) of Technical Specification 3.6.3.1.

To prevent recurrence, construction personnel have been instructed of the necessity of caution while working in the area of switches. ,

In addition, ' station personnel have been instructeu to be observant of situations

which may lead to the changing of disconnect panel suitch positions, so that,nroner management personnel may be contacted.

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Failure Data: No previous similar events have occurred.

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