ML19343C222

AO 50-219/74/40:on 740715,insp Located Inoperable Bergen- Paterson Hydraulic Shock & Sway Arrestor on South Core Spray Sys in Drywell.Caused by Loss of Hydraulic Fluid Due to Burns on Main Control Rod.Units Replaced

ML19343C222
Person / Time
Site:	Oyster Creek
Issue date:	07/24/1974
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-50-219-74-40, NUDOCS 8103040453
Download: ML19343C222 (2)

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jersey Central Power & Light Company o MADISON AVC . T PUNCH BOWL ROAD

• MORRISTOWN, N.J. 07960

• 201-539-6111

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, Utilities corporation SVETEm diSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/40 Report Date July 24, 1974 Occurrence Date July 15, 1974 Identification of Occurrence Inoperability of one Bergen-Paterson hydraulic shock and sway arrestor located on the south core spray system in the drywell. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15D.

Conditions Prior to Occurrence The reactor was shut down with reactor coolant temperature less than 212*F.

Description of Occurrence An inspection of the drywell shock and sway arrestors, Bergen-Paterson Type HSSA-10, located an inoperable unit on the south core spray system. The inoperable unit was installed in the drywell during the spring refueling outage. In addition, another inoperable unit and a leaking unit were found on the south feedwater loop.

Apparent Cause of Occurrence The cause of the snubber inoperability was a loss of hydraulic fluid. Exacination of the units revealed small cuts on the main cylinder shaft U-cups caused by burrs on the main piston rod when the U-cups were installed during the rebuilding procedure. The U-cup is installed on the main piston rod in conjunction with the piston rod end assembly. As a result, one cannot determine if the U-cup Sys3046463

i Abnormal Occurrence No. 50-219/74/40 Page 2 is cut during installation on the rod. Burrs on the piston rod have been observed on both rebuilt units and on some newly received main piston rods. The burrs on piston rods removed from previously leaking units may have been created during the disassembly of the snubbers.

Analysis of Occurrence The safety significance of this occurrence was a partial loss of seismic re-straining ability for the affected system. Had the plant suffered a design bases earthquake, the probability that the south core spray system would have suffered structural damage was increased.

Corrective Action The failed units were replaced with identical snubbers which had been rebuilt with ethylene propylene material and pressure tested to 4,000 psi.

The Plant Operations Review Committee directed that a precaution be added to the snubber reassembly procedure to insure that one would be aware of the possibility of these burrs on the mair piston rods. In addition, the mechanics have been verbally cautioned to watch for these burrs and to file them smooth whenever they are found. A test, supplemental to the 4,000 psi pressure test, will be implemented. This test includes a soaking period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> followed by a reexamination for evidence of leakage by the U-cup.

Failure Data Manufacturer - Bergen-Paterson Type - HSSA-10 Serial Number - 487525

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