05000312/LER-1981-014, Forwards LER 81-014/03L-0.Detailed Event Analysis Encl

Forwards LER 81-014/03L-0.Detailed Event Analysis Encl

ML19350D122
Person / Time
Site:	Rancho Seco
Issue date:	04/03/1981
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19350D123	List: 05000312/LER-1981-014, Forwards LER 81-014/03L-0.Detailed Event Analysis Encl 05000312/LER-1981-014-03, /03L-0:on 810306,unacceptable Leak Rate Obtained During Local Component Leak Rate Test on Reactor Bldg Penetration 34.Caused by Motor Pinion Gear Key Backed Out of Keyway & Sheared Off.Set Screw Added to Operator Key
References
NUDOCS 8104130379
Download: ML19350D122 (2)

LER-1981-014, Forwards LER 81-014/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3121981014R00 - NRC Website

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' SACRAMENTO MUNICIPA1. UTILITY DISTRICT [] 6201 S Street. Box 15830. Sacramento. California 95813; (916) 452 3211 April 3, 1981 Mr. R. H. Engelken, Director Region V Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission

'1990 North California Boulevard

., 7 g

Walnut Creek Plaza, Suite 202 e.)

Walnut Creek, CA 94596 (o

OperatingLicenseDPR-St['

Re:

'4 h g Q -9 4 Docket No. 50-312 F_

O Reportable Occurrence 1g1}

Wlr

Dear Mr. Engelken:

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so in accordance with Technical Specificatiohs 'f67]RahhkSeco Nuclear Generating Station, Section 6.9.4.2b and Regulatory G'ul'de 1.16, Revision 4, Section C.2.b(2), the Sacramento Municipal Utility District is hereby submitting a thirty-day report of Reportable Occurrence 81-14.

On March 6, 1981, while performing SP 205.02, Local Component Leak Rate Surveillance Testing, leakage through Reactor Building pene-tration No. 34 was unacceptable. Penetration No. 34 is the reactor building purge inlet isolated by valves SFV-53503 and SFV-53504.

Subse-quent investigation revealed that SFV-53504, the inside isolation valve, was not completely closed.

To determine the cause of the valve failing to stroke to the fully closed position, the valve operator was inspected. The inspection revealed that the key between the motor pinion gear and the motor shaft had backed out of the keyway and sheared off. The sheared off portion of the key had lodged in another section of the operator causing damage to the tripper spring and disabling the de-clutch link.

Maintenance personnel refurbished the shaf t keyway, installed a new key and tripper spring, and properly positioned the de-clutch link. Additionally, to prevent the key f rom backing out of the keyway, a modi fication to the open ended keyway design was made.

This modifi-cation included drilling and tapping a 1/8" set screw hole over the key and machining a depression i.1 the key to receive the setscrew. The additional setscrew was then positioned so that it is retained by a lock wire.

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8104130379

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April 3,1981

Mr. R. H. Engelken The _ District contacted the manufacturer of the valve operator, informed them of the problem encountered, and discussed the modification made to the keyway design. The manufacturer responded that the open resulted in ended keyway design has been standard procedure and has not previous fleid problems.

However, the manufacturer determined the District's modifi-cation to be acceptable and concurred with the District's intent to The duplicate perform the same modification on a duplicate operator.

operator is used on SFV-53605, the reactor building purge outlet *

,ve, to the same service conditions as the SFV-53504 valve and is subject operator.

Upon receiving the manufacturer's approval / concurrence of the Both of the modification, the operator for SFV-53605 was modi fied.

valves were tested per their applicable surveillance procedures, following the modification and prior to being determined as operable.

The components associated with this event are Model SM8-3 Valve Actuators manufactured by Limitorque Corporation.

There were no transients nor power reductions associated with this event.

Respectfully submitted, A

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N[r John

. Mattimoe

' ' Assistant General Manager and Chief Engineer JJM:HH:rm cc:

ISE Washington (30)

MIPC (3)

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