ML20084J222

Ao:On 730721,during Plant Shutdown,Eight Drywell Snubbers Discovered Missing Hydraulic Fluid.Caused by Seal Failure Creating Leakage Path.Snubbers Replaced.Forwards Snubber Repair Activities..., Summary Rept

ML20084J222
Person / Time
Site:	Oyster Creek
Issue date:	08/06/1973
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084J225	List: ML20084J222 ML20084J231
References
IEB-73-03, IEB-73-3, NUDOCS 8305120256
Download: ML20084J222 (3)

Text

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t Jersey Central Power & Light Company M ADISoN AVENUE AT PUNCH SoWL Ro AD e MoRRISToWN, N.J. 07960 e 539 6111 O

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Deputy Director for Reactor Projects o1w Directorate of Licensing

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/d' United States Atomic Energy Commission Washington, D. C.

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Subject:

Oyster Creek Station Docket No. 50-219 Hydraulic Shock and Sway Arrestor Failure The purpose of this letter is to formally submit in writing our Summary Report, dated July 16, 1973, on Snubber Repair Activities during the 1973 Oyster Creek Refueling Outage.

This report was sent to your office earlier in a preliminary form. This report is also responsive to Items B.2.a to e inclusive in your R. O. Bulletin No. 73-3, dated July 27, 1973.

Also in. answer to Item B.2.c all units are of the same model identification, HSSA-10.

In addition we wish to advise in writing that the plant exper-ienced the failure of eight Hydraulic Shock and Sway Arrestor units located on the Emergency Condenser, Core Spray, Main Steam, Feedvater, and Shutdown Cooling system in the dryvell. This event is censidered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15d.

Notification of this event, as required by the Technical Specifications, paragraph 6.6.2.a, was made to AEC Region I, Directorate of Regulatory Operations, by telephone on Friday, July 27, 1973, at 10:00 a.m.

The plant was shutdown on July 21, 1973 because of high uniden-4 tified leakage in the dryvell.

It was decided at this time to perform an inspection on the dryvell snubbers which had been rebuilt during the Spring outage.

It was discovered that eight of the sixty-two dryvell snubbers were missing hydraulic fluid in varying amounts, thereby resulting in their inoperability. The units involved are tabulated belov by serial number and location:

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6097 05000 COPY SENT REGION '

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Mr. Giambusso August 6, 1973 s

Serial Number Location 487h91 Shutdown Cooling h87h95 Core Spray h87h99 Emergency Condenser 487516 Shutdown Cooling.

487557 North Feedvater 487561 Emergency Condenser 487562 Emergency Condenser h8757h Emergency Condenser The oil 1cas has been attributed to seal failure creating a leakage path. The exact mechanism of seal failure is presently under investigation by Disogrin Company, Bergen Paterson and Rex Hanna. Based on discussion with Bergen Paterson and Rex Hanna at the Oyster Creek site on August 2, two points were recognized. Both of the silicone base radiation resistant fluids (SF1017 and SFil54) possess an aromatic constituent. in their chemical make-up which is capable of replacing out a plasticizer in the soft millable gum polyurethane seals. Loss of the plasticizer cause both a reduction in seal volume and a loss in seal effectiveness. It is believed that prolonged ex-peure et elevated terre *stwas is a fertor in this nll attack on the aasla.

This point is amplified by noting the location of the recent failures, six of which were above the biological shield where dryvell t' mperatures are the e

greatest.

Corrective action was taken by replacing the failed units with eight new spares.

The significance of this type failure is in the event of a design bases earthquake no credit could have been taken for the seismic restraining ability of the failed units, the probability was increased that the piping systems affected would go into resonant vibratien and possibly fail.

The following surveillance schedule is proposed:

1.

Inspect all dryvell snubbers as made available by scheduled or forced shutdowns requiring deinerting of the dryvell, ex-cepting shutdowns that occur within a four week period.,

2.

We vill inspect all dryvell snubbers within six weeks from July 28, 1973. Future surveillance schedules vill be based on the results of this inspection. Our intentions will be

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made known to the Commission in a timely manner.

3.

The snubber inspection. vill consist of the following:.

a) Hydraulic; fluid level check b) Inspection of piston rod fcr scratches.to indicate; possible nisalignment between the rod and outboard bearing

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Mr.Giambdsso August 6, 1973 c) Check to see if eyebolt nut is loose, which would indicate unit is free to move.

Enclosed are forty (40) copies of this report, s

Very truly yours, l

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(' N% tu Donald A. Ross Manager, Nuclear Generating Stations DAR/pd I

Enclosures cc:

Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region I f

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