05000271/LER-1981-020-03, /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

/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 File:NorthStar Vermont Yankee icon.png
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: 05000271/LER-1981-020, Forwards LER 81-020/03L-0 05000271/LER-1981-020-03, /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
References
LER-81-020-03L, LER-81-20-3L, NUDOCS 8108210257
Download: ML20010C948 (2)

LER-1981-020, /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

Event date:
Report date:
2711981020R03 - NRC Website

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

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8 60 si OOCKET NUMSER 68 69 EVENT OATE 74 75 REPORT OATE 80 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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l [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

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The A Cont. Spray Subsystem was tested and verified operable in accordanae l

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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.

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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.

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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.

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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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