ML19211D265

LER 79-035/03L-0:on 791215,during Surveillance Testing Msivs,Inboard Valve V2-80A in Main Steam Line a Closed But When Repositioned to Open,Was Found to Be Partially Open.Caused by Spring Plate Binding on Guide Shaft

ML19211D265
Person / Time
Site:	Vermont Yankee
Issue date:	01/14/1980
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19211D262	List: ML19211D261 ML19211D265
References
LER-79-035-03L, LER-79-35-3L, NUDOCS 8001170370
Download: ML19211D265 (2)

Text

LICENSEE EVENT REPORT

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74 75 REPORT D ATE SC EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 0 2 o 3 See attached sheet i o 4  !

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1 7 l0 l0 l0 l@lZ l@l NA PERSONNE L INJURIES NUMBER DESCRtPTION }

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VTVYS1 05000271 LER 79-35/3L EVENT DESCRIPTION AND PROBABLE CONSEOUENCES During routine surveillance testing of the MSIVs, inboard valve V2-80A in the "A" main steam line was successfully closed but when repo-sitioned to open was found to be only partially open. This was verified by the valve's position lights and main steam flow indication. Mainte-nance personnel investigated the occurrence and observed that the actu-ator spring plate was binding on its guide rods.

The actuator is designed such that either air or spring force is capable of closing the valve. Tech. Spec. Section 3.7.D.1 requires that these valves be operable during reactor power operation. Although V2-80A was capable of closure pneumatically, the design bases of MSIVs requires that they be capsble of operating on both air and spring force during re-actor operation. The plant was maintained as allowed by Tech. Spec. Sec-tion 3.7.D.2 when V2-86A, the outboard MSIV in main steam line "A", was closed. This valve was maintained closed during the time V2-80A was de-clared inoperable. Based on the above, there were no adverse consequences to the health and safety of the public. Similiar occurrences were re-ported to the Commission in R0 79-11/3L and RO 79-20/3L.

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS The cause of this occurrence is attributed to the spring plate binding on the guide shaf t(s). The surface of the guide shafts was smoothed. The valve was successfully stroked several times, verified op-erable and returned to service. The valve was manufactured by Rockwell, Model 1612 JMMY Flite Flow Stop Valve.

During a recent unscheduled outage, additional checks and inspec-tions of the valve actuator were performed as recommended by the manuf ac-turer. These provided no new information. Additionally, new guide rods have been ordered and will be installed at the next available opportunity.

The manufacturer will provide a further evaluation of the shaft. binding.

Appropriate actions or modifications, if any, will be initiated as soon as practical following receipt of the evaluation.

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