05000312/LER-1978-015, Forwrds LER 78-015/01T-0

Forwrds LER 78-015/01T-0

ML20150E166
Person / Time
Site:	Rancho Seco
Issue date:	12/04/1978
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Engelken B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20150E169	List: 05000312/LER-1978-015, Forwrds LER 78-015/01T-0
References
NUDOCS 7812110170
Download: ML20150E166 (2)

LER-2078-015, Forwrds LER 78-015/01T-0

Event date:
Report date:
3122078015R00 - NRC Website

text

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lid _a SACRAMENTO PAUNICIPAL UTILITY DISTRICT O $201 S Street, Box 15830, sacramento, California 95813; G16) 452 3211 I

December 4, 1978 I i

Director of Regulatory Operations ATTH: Mr. R. H. Engelken i NRC Operations Office Region V i 1990 florth Cali fornia Boulevard I Walnut Creek Plaza, Suite 202 -

Walnut Creek, California 94596 ,

i Re: Operating License DPR-54 l Docket No. 50-312  !

Reportable Occurrence 78-15 ,

Dear Mr. Fogelken:

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e in accordance with Technical Specifications for Rancho Seco Nuclear Generating Station Section 6.9.4. l(!)' and Regulatory Guide 1.16, Revision l 4 Section C.2.a(9), the Sacramento Municipal Utility District is hereby '

submitting a fourteen-day Reportable Occurrence 78-15, which was initially I discussed wi th Mr. A. Johnson of your of fice during his inspection conducted  ;

November 28 - 30, 1978.

On November 20, 1978, while performing the Refueling Cycle Hydraulic Snubber Testing, one unit of the representative sample of ten was found in- l operable, in accordance with Technical Specifications Section 4.14.4,  !

another representati- sample of ten units was tested. Three additiorial }

!noperable units were found in this second group. All of the failed / inoperable units encountered were Bergen-Paterson units, and the District concentrated ,

on testing only Bergen-Paterson units in the succeeding groups of ten. This course of action was predicated upon our Technical Specifications, which addresses failures shown to be unique to one brand make. Correspondence has been initiated with Mr. Ried, of NRR, concerning a letter of concurrence of the test program followed.

A total of 53 Bergen-Paterson units were tested. Seven (7) units exhibited no lockup in the retraction direction. Investigation revealed i damage to the poppet and seat on the retraction side of the valve block. Five '

of these seven units were found to sti11 have the poppet spring entrapped 1 between the poppet and seat of the valve block. These failures have been j attributed to abusive handling during reinstallation after the 1977 test j program. During that time it was discovered that after initially adjusting  !

the units to their proper length, the spring-loaded accumulator in the Bergen- I Paterson units caused the snubber to expand if not installed soon after setting. f I

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R. H. Engelken Page 2 December 3. 1978 Personnel installing the units were discovered striking the shaft end of these units against walls and floor in order to shorten them. Upon dis-covery of this practice, the work was stopped and several units retested.

No failures were discovered. As a result, the reinstallation was continued with instructions to personnel that if length adjustment was necessary, such adjustments were to be made in the test fixture. The practice of striking the shaft end of the units against walls and floors was discontinued. I Although no failures were detected in those units retested, the District l engineer cognizant of the snubber test prog am feels that the failures presently observed are a result of the mishandling in 1977 1 1

The two remaining failures encountered were separate modes of failure.

One unit would not lock up in the extension direction due to excessive poppet valve leakage. The other unit would not lock up in either direction. Dis- i assembly revealed a broken piston ring. Since these two units, of the 53 units tested, were the only ones to exhibit problems unrelated to the other failed units, they are felt to be isolated cases.

The attached table identifies the failed units and their mode of fallure.

Since the plant was shut down for refueling, there was no plant transient or sh"tdown associated with this event.

Respectfully sus ~.itted, 3*

l- .y c$lc.uR Gh.'J.Mattimoe Assistant General Manager and Chief Engineer JJM:RJR:HH: jim Attachments cs: Director, MIPC (3)

Director, IE (30) 1

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