ML19317F373

RO 270/77-07:on 770419,reactor Bldg Isolation Valve 2CS-5 Determined Inoperable During Functional Testing.Caused by Application of Excessive Torque to Close Valve.Valve to Be Repaired

ML19317F373
Person / Time
Site:	Oconee
Issue date:	05/19/1977
From:	DUKE POWER CO.
To:
Shared Package
ML19317F371	List: ML19317F370 ML19317F373
References
RO-270-77-07, RO-270-77-7, NUDOCS 8001140625
Download: ML19317F373 (2)

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DUKE-POWER COMPANY OCONEE UNIT 2 ,

g port No.: R0-270/77-7 Report Date_: May 19, 1977 Occurrence Date: April 19, 1977 Facility: Oconee Unit 2, Seneca, South Carolina RB isolation valve, 2CS-5, determined inoperable Identification _of Occurrenc_e_: during functional testing Unit at 100 percent full power Conditions Prior to Occurrence:

Description of Occurrence:

h On April 19, 1977, during the performance of valve functional ld testing, not bet e component drain pump Reactor Building isolation valve 2CS-5 couThis valve is an En to the closed position.

cycled from the openSafeguards valve and is required to close upon receiving a signal in order to assure containment integrity.

dent the redundant containment isolation valve, 2CS-6, was closed.

Valve 2CS-5 was determined to be manually operable and was locked in its A temporary closed ES position within four hours after the functional test. i operating procedure has been approved which will establish administrat veis ne control over the use of valve 2CS-5 when it for quench tank operation.

Apparent Cause of Occurrence:

Investigation revealed that valve 2CS-5 requiredofexcessive The application excessivetorque torque to close electrically from the Control Room.

resulted in the opening of either the overload limit switch or the torque limit switch causing the trip of the magnetic contactor which supplies power to the valve drive unit.

breaker by manually closing the

.The valve was operable locally at the The specific cause of this magnetic contactor to the valve drive unit. incident has not_ been d during power operation.

Analysis of Occurrence:

Valve 2CS-S was determined to be manually operable and capable of per-Administrative forming its intended ES function when locked closedassure that whe control will S operation, actuation.

it can be manually closed promptly in the event of during 'the incident and is also capable of isolating the line if required.

E.f Contain.2ent integrity was not af fected by this inciden 8001140&g u

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Corrective Actfon_: '

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Valve' ' 2C S- 5 willibe-repaired during the next appropriate unit outage.

the_interimi'a-temporary procedure has been prepared and approved to operate the: valve when needed from the breaker ' cabinet where the magnetic contactor

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can be manually closed.

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