ML19353A393

LER 81-001/01P-0:on 810101,MSIVs 80B & 86A Closing Time Exceeded Tech Spec Limit of 5-s & Relay 5A-K3F Failed to de-energize.Cause Under Investigation

ML19353A393
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	01/02/1981
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19353A391	List: ML19353A390 ML19353A393
References
LER-81-001-01P, LER-81-1-1P, NUDOCS 8101080352
Download: ML19353A393 (2)

Text

Nf3C FORM 366 U. S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT LER 81-01/IP b%_/ CONTROL SLOCK: l } l l l l] (TLEASE PAINT OR TYTE ALL REQUIRED INFoRMATION) i e i c i 611 7 9 I v itCENSEE l T ! vCOOE l Y l S I ll@l 01 0! -l LICENSE 14 15 Ol OlNUMBER 01 01 O! -l 010l@l411l111111@l 25 26 L10ENSE TYPE 40 l

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EVENT OESCRIPTION AND PROBABLE CONSEQUENCES h l

io!2l l Iojal l See attached sheet. l l

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l i i c l l Reactor power was reduced, the turbine-generator was taken off line and the reactor l l3 l1j l mode switch was placed in the STARTUP position. The cause of the MSIV problems is I i,;7; l presently being investigated. The results of that investigation and corrective l l1 j 31 l action taken will be detailed in a followup report. I li i4 11 80 I

7 8 9 STA S  % POWE R CTMER STATUS 01500 RY 0 SOCVERY DESCRIPTION l

l1 l5 l l C l@ l0 l 3 l 8 l@l NA l l B l@l Durine Surveillance Testine ACTIViTv CONTENT DELE ASEO OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELEASE l1 l6l 7 8 9 h 10 l

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NAME OF PREPARER Y PHONE. (802) 257-7711 2 81 ol 08 o 3s a

VTVYS1 05000271 LER 81-01/lP EVENT DESCRIPTION AND PROBABLE CONSEQUENCES While performing surveillance testing at 37% reactor power, MSIV 80B and 86A were found to close in 5.5 and 5.3 seconds, respectively, which exceeds the T. S. limit of 5 seconds. As required by T. S. Section 3.7.D.2, MSIV 80A and 86B were closed. This created a half scram condition in the A Trip System of the Reactor Protection System.

In addition, it was determined while testing MSIV 80C, that relay 5A-K3F failed to deenergize. The combination of the failure of relay 5A-K3F to deenergize and the need to close both MSIV 80A and 86B could have resulted in a situction with three steam lines isolated without creating a direct reactor scram.

Similar slow MSIV closure times were reported in LER 79-29 and LER 78-32.

MSIV limit switch failures were reported in LER's 78-8, 76-44, 75-20 and 73-35.

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