ML19347C822

Ao:On 730908,plant Shut Down to Inspect Hydraulic Shock & Sway Arrestors on Piping Sys in Drywell Bldg.Insp Revealed 23 Failed Arrestors.Caused by Loss of Hydraulic Fluid from Failed Millable Gum Polyurethane Seals

ML19347C822
Person / Time
Site:	Oyster Creek
Issue date:	09/21/1973
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8103040954
Download: ML19347C822 (3)

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EL SlcDON M ADISoN AVENUE AT PUNCH BOWL Ro AD e MoRRISToWN, N.J. 07960 e 5 111 CllEK 6

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? [( h h y Mr. A. Giambusso gp p4 '

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Deputy Director for Reactor Proj,ects v "' 4.

Directorate of Licensing United States Atomic Energy Commission r'

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Washington, D. C. 20545

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Subject:

Oyster Creek Station Docket No. 50-219 Ilydraulic Shock and Sway Arrestor Failure The purpose of this letter is to provide information pertaining to additional hydraulic shock and sway arrestor failures at the Oyster Creek station. A written report as requested in R. O Bulletin No. 73-4 will be submitted upon completion of our inspection program.

This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15.D. Notification of this event as required by the Technical Specifications, paragraph 6.6.2.a. , was made to AEC Region 1, Directorate of Regulatory Operations, by telephone on September 10, 1973, and in writing to Mr. B. Greenman on September 11, 1973, during his visit to the site.

As committed to in a letter from Mr. D. A. Ross to Mr. A. Giambusso dated July 27, 1973, the plant was shut down on September 8,1973 for the purpose of inspecting the hydraulic shock and sway arrestors located on piping systems throughout the drywell and reactor building. Partial inspection has revealed the failure of 23 out of 66 hydraulic shock and sway arrestors on piping systems in the drywell and 19 out of 72 (so far inspected) external to the drywell, some of which are associated with engineered safeguards systems. All 25 Grinnell shock absorbers on the five recirculation loops in the drywell were inspected and found to contain varying amounts of oil. None, however, were without oil and, consequently, are considered to be operabic. They have been refilled as necessary under normal maintenance. .

The snubbers were made inoperable due to excessive loss of hydraulic l fluid resulting from the failed millable gun polyurethane seals.

The failed hydraulic shock and sway arrestors are being, or will be, replaced using snubbers rebuilt with seal kits supplied by the Bergen-Paterson Pipe Support Company. Further, all the remaining units in the drywc11, although

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i Mr. Giambusso September 21, 1973 noted to be satisfactory during this inspection, are being removed and rebuilt to replace certain critical millable gum polyurethane seals with molded poly-urethane seals in the kits noted above. The seals provided to us by Bergen Paterson should provide a longer service life than those previously utilized at Oyster Creek.

The failures were such that they affected both core spray and both emergency condenser systems in the drywell and both containment-spray systems external to the drywell. The loss of shock absorber operability results in a reduction in the ability of the associated piping systems to withstand a design bases earthquake. Additionally, failed shock absorber restraints were also dis-covered on the electromatic relief discharge blowdown lines. Failure cf these shock absor'bers would increase the probability of damage to the relief valve dis-charge piping during periods of multiple valve actuation.

1 The following program is proposed which is intended to provide a l permanent modification of our hydraulic shock absorber units to assure their j proper long term operation:

We will conduct our next reinspection of our Bergen-Paterson hydraulic shock absorbers following approximately 6 weeks and no longer than 12 weeks after the plant has been at operating temperature following this shutdown.

The inspection will include all the items as identified in R. O. Bulletin No. 73-4 dated August 17, 1973. At the time of the reinspection, a prompt tele-phone report will be made to advise Region I of our findings. A written report will also be provided as specified in the above mentioned R. O. Bulletin.

Due to the significant radiation exposure associated with the inspection and complete rebuild of all our Bergen-Paterson shock absorbers (approximately 20 man-rem to date for this inspection and repair), we believe it most desirabic to have the reinspection period coincide with the availability of an ultimate modification, if at all possible.

Our Generation Engineering Department is currently pursuing two equally acceptable long term solutions. First, General Electric Company has underway a development program with the snubber and seal manufacturer to determine that the permanent satisfactory seal will be of ethylene propylene material. Once this is determined and agreed to be all parties involved, we would purchase enough seal kits to rebuild all our Bergen-Paterson shock absorbers or consider purchasing new Bergen-Paterson units, utilizing the ethylene propylene seal material for installation in the drywell.

A second solution currently bein'g pursued is the consideration of re-placing all the Bergen-Paterson shock absorbers presently in the drywell with those of a different manufacturer.

Selection of either alternate will be considered in view of the long term suitability to resolve the hydraulic shock failure problem, timely avail-ability of material and minimum exposure to station personnel implementing the repair.

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Mr. Giambusso September 21, 1973 --~s .

We will keep the regional office advised of our progress in arriving at a timely long range solution.

We are enclosing forty copies of this report.

Very truly yours,

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Donald A. Ross Manager, Nuclear Generating Stations es Enclosures cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region I  !

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