ML20010C948

LER 81-020/03L-0:on 810715,four Motor Mount Bolts on Limitorque Operator for Valve RHR-31B Found Sheared, Rendering Containment B Spray Subsystem Inoperable.Cause Unknown.Motor & Mounting Blocks Replaced

ML20010C948
Person / Time
Site:	Vermont Yankee
Issue date:	08/14/1981
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010C947	List: ML20010C946 ML20010C948
References
LER-81-020-03L, LER-81-20-3L, NUDOCS 8108210257
Download: ML20010C948 (2)

Text

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l- MRC FORM 386 U. S. NUCLE AR R EGULATORY COMMISSION il in LICENSEE EVENT REPORT LER 81-20/3L l

CONTROL SLOCK: l I

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(PLEASE NINT OR TYPE ALL REQUIRED INFORMATION)

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7 8 60 si NUMSER 68 EVENT OATE 74 75 REPORT OATE 80 l

EVENT OF"CBIPTION 'NO PROBABLE CONSEQUENCES h 10121 lWhile on a pl.nt tour, the Asst. Plant Supt. observed that 4 motor mount bolts on ]

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[TTTl l the limitorque operator for valve RHR-31B (Upper Co. t. Spray) were sheared. This  !

10141 l valve rendered the B Cont. Spray Subsystem inoperable <h i ch h contrary to L S. 3. I I O vTl 15.B.1. The A Cont. Spray Subsystem was tested and verified operable in accordanae l 10161 l uf th T. S. 4.5.B.2. There were no consequences to the publ ic heal th and safety. I 10171 l No similar occurrenc ?s have been reported to the commission. l l 10181 l I 30

( 7 8 9 l SYSTEM CAYSE CAUSE C C,M P VALVE CODE .00E SUSCODE COMPONENT CODE SU8 CODE SUSCODE Lo_L.1 7 8 I s I n l@ Ld@ LaLJ@ l f3v I A l t I v i o f P l@ W@ Lz.J 9 10 11 12 18 19 20 .

SE CUENTI AL OCCURRENCE REPORT REVISION EVENTYEAR REPOR T NO, CODE TY PE N O.

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CAUSE DESCRIPTION Arl0 CORRECTIVE ACTIONS h j l i l o ] lThe cause of this event is unknown. The motor and mounting bol ts were replaced and I i i I the valve was sat isfact orily tested. I i 7 I l lilal l I LLilj L I r a s 80 ST v  % POWER OTHER STATUS DIS O RY DISCOVERY OESCRIPTION

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES l-

, ' While on a ; plant tour, the Assistant Plant Superintendent obercved

that. 4 motor mount ' bolts on the limitorque operator for valve R' '

l (Upper Containment Spray) were sheared. This valve rendered the .

j. Containment Spray Subsystem inoperable which is contrary to Tech. ,ec.

Section 3.5.B.l. Operability of the A and C RHR Service Water Pumps

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was verified i=nediately. Approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> later, the A and C RHR ' pumps ar.d the heat exchanger were verified operable in accordance l with: Tech. Spec. Section 4.5.B.2. Subsequent to the completed alternate testing of t.he subsystem, the RHR 31B valve was tested satisfactorily.

As a result of this event..there were no consequences to the pun 1fc health and -safety. No, similar occurrences have been repcrted to the L -commission.

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS The cause of this event is unknown. The motor and mounting bolts were replaced and the valve was satisfactorily. . tested. Investigation of maintenance records has revealed that there have been no similar failures of this type in this system since initial operation. lui evaluation of the basis . for sizing 1the. mounting bolts will be accomplished. In addition, the importance and . timeliness lof the required alternate testing was reviewed with the affected operators.

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