ML20085F037

AO BFAO-50-260/754W:on 750123,four Bergen-Paterson Arrestors Found W/Unacceptable Low Amount of Oil Present During Shock Arrestor Insp.Caused by Small Nick in Sealing Surface of Accumulator Piston Seal.Recommended Seals & O-rings Used

ML20085F037
Person / Time
Site:	Browns Ferry
Issue date:	01/31/1975
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8308180237
Download: ML20085F037 (3)

Text

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TENNESSEE VALLEY AUTHORITY 1

CH ATTANOOGA, TENNESSEE 37401 -

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January 31, 1975 0.1 ' /j<,..,

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Mr. Edson G. Case '?. - '

Acting Director of Licensing

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4D ~, ._, 4 U.S. Nuclear Regulatory Comission Washin6 ton, DC 20545

Dear Mr. Case:

TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCLEAR PLANT UNIT 2 -

DOCKET NO. 50-260 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCEREPORTBFAO-50-260/754W The enclosed report is to provide details concerning four Bergen-Paterson arrestors which were found with an unacceptable low amount of oil present in the arrestor unit and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973.

This event occurred on Browns Ferry Nuclear Plant unit 2 on January 23, 1975.

Very truly yours, TENNESSEE VALLEY AUTHORITY

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E. F. Thomas

/>Director of Power Production Enclosure CC (Enclosure):

Mr. Norman C. Moseley, Director U.S. Nuclear Regulatory Comission Regional Office 230 Peachtree Street, NW., Suite 818 Atlanta, Georgia 30303 Y

8308180237 750131 PDRADOCK05000ljD S -

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. ABNORMAL OCCURRENCE REPORT ,

Report No.: BFAO-50-260/75W i Report Date: January 31, 1975 ' ,

Occurrence Date: January 23, 1975 _d Facility: Browns Ferry Nuclear Plant unit 2 p s

Identification of Occurrence During an inspection of shock arrestors, the following four Bergen-Paterson arrestors were found with an unacceptable low amount of oil present in the arrestor unit.

One arrestor on the control rod drive pump suction line inside .

the drywell.

One arrestor on a residual heat removal containment spray line outside the drywell.

Two arrestors on the reactor core isolation cooling system turbine discharge line.

Conditions Prior to Occurrence The reactor was in the cold shutdown condition during an outage.

Description of Occurrence ,

The deficiencies in the arrestor units were found during an inspection of all-Grinnelland Bergen-Paterson hydraulic shock and sway arrestors.. .,- S.*. . ,

i Designation of Annarent Cause of Occurrence -

! The apparent cause of the low fluid level in the arrestors on the control rod drive and residual heat removal lines was a small nick in the sea m g surface

of the accumulator piston seal. This seal contains an "0" ring inside a U-cup.

This "O" ring retards diametrical compression of the entire seal during installation of the seal and operation of the arrestor. The two arrestors on

,s the reactor core isolation cooling system turbine discharge line had an i unacceptable low amount of oil because all the polyurethane seals in the valve assemblies had not been replaced. It appears that, during the rebuild program j in which the polyurethane Jeals were to be replaced with ethylene propylene l seals, an error was made which resulted in leaving one polyurethane seal in one arrestor and two polyurethane reals in the other. These polyurethane seals had deteriorated and allowed fluid to leak out.

l Analysis of Occurrence No damage to systems, components, or structures was experienced; no personnel injuries or exposures were involved; no radioactive materialc were released;

- and there were no adverse effects to the public health and safety as a result of this occurrence. 3 l .

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O -=- 0 1-t Corrective Action The Bergen-Paterson arrestors which had an unacceptable low amount ofo' il were '

disassembled, inspected, and reassembled using the reco= ended ethylene propylene seals and "O" rings. Care was taken to prevent inadvertent nicks on seal surfaces when rebuildina.

Failure Data

%draulic Pipe Shock Arrestors Manufacturer - Bergen-Paterson s  %.

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9 6

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0 6 9 %

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4 0

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