ML20062D587

/03L-1 on 780420:during Routine Hydraulic Snubber Surveillance Inspec,Snubber Mark 149 Was Found Inoper Due to Empty Fluid Reservoir & Mark 144 Was Found W/Missing Cotter Pin,Due to Component Failure

ML20062D587
Person / Time
Site:	Quad Cities
Issue date:	10/25/1978
From:	Vahrenwald J COMMONWEALTH EDISON CO.
To:
Shared Package
ML20062D584	List: ML20062D581 ML20062D587
References
LER-78-010-03L, LER-78-10-3L, NUDOCS 7811240240
Download: ML20062D587 (3)

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REPORT DAT E EVENT DESCRfPTION AND PROS ASLE cONSEQUE'JCES h ITTF1 L0n April 2_Q.1978. while oerformino a rogtine Hydraulic Snubber Surveillance insoection l '

Lo y [on Unit One, Hydraalic Snubber Mark 149 was l'ound to be Inoperable due to an empty l l o l .: ] l fluid reservoir. At this time, snubber Mark 144 was found to have a missing cotter l

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42 43 44 4; CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 litol lThe cause of this event is due to component failure. Snubber Mark 149 failed due to l L' ' i_J l hardened o-rings and seals. Snubber Mark 144 did not fall and was still functional at I ri TT1 I the time of this surveillance. A new pivot pin was made for Snubber Mark 144 and the l l i l 3 l l cotter pin was replaced. l 11 141 l l 7 E 9 80 i

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l. LER NUMBER: LER/R0 78-10/03L-1

11. LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill. FACILITY NAME: Unit One IV. DOCKET NUMBER: 050-254 V. EVENT DESCRIPTION:

On April 20, 1978, with Unit One shutdown for a routine main-tenance outage, a hydraulic snubber inspection was performed in accordance with procedure QMS 800-14. Hydraulic snubber Mark 149 was found to be Inoperable due to an empty fluid reservoir. At this time, a second snubber, Mark 144, was also found to have a missing cotter pin. However, this snubber was not inoperable, and would have performed its intended function had a seismic event occurred. Work Requests 2044-78 and 2045-78 were initiated to repair the snubbers prior to unit startup as required by Technical Specification 3.6.l.4.

Snubber Mark 149, located on reactor recirculation pump suction line 1-0202B-28"-A, was found to have an empty oil accumulator.

Snubber Mark 144, located on reactor recirculation pump dis-charge line 1-02018-22"-A, was found to have a missing cotter pin and a slightly deformed pivot pin.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

Snubbers are designed as a safety measure to prevent unrestrained pipe motion in the event of an earthquake, while allowing pipe movement caused by thermal expansion during plant operation.

The probability of a seismic disturbance is low; therefore, the effect on the safety of the plant as well as the environs is minimal. Also, there were operable snubbers in close proximity to both of the above mentioned snubbers which further lessen the severity of this occurrence.

1 Vll. CAUSE:

Snubber Mark 149, found with an empty reservoir, had failed due to apparent hardening of the o-rings and seals, thereby allowing the oil to drain out. No loose fittings or damaged o-rings were found during disassembly.

l A closer examination of the Mark 144 snubber revealed that the l pivot pin, being slightly deforced, was secure in its clevis and would not have fallen out due to the loss of the cotter pin. There were no other defects on this snubber, and there was ample oil in the fluid reservoir. ~

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o .= 0 During the preceeding surveillance, all snubbers were operable.

The hydraulic snubbers are manufactured by Bergen-Paterson Company.

Vill. CORRECTIVE ACTION:

Sntbber Mark 149 was rebuilt and was tested for proper operation prior to Installation. A new pivot pin was manufactured #or snubber Mark 144, and the missing cotter pin was replaced af ter installation. Both snabbers were installed in their original locations.

The preceeding three snubber inspections showed no Inoperable snubbers on Unit One.

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