ML20085G861

AO BFAO-50-260/7420W:on 741017,during Planned Insp of Hydraulic Piping restraints,Bergen-Paterson Hydraulic Shock & Sway Arrestors Found W/Unacceptably Low Oil Levels.Caused by Seal Nicks Due to Burrs on Piston Rod End

ML20085G861
Person / Time
Site:	Browns Ferry
Issue date:	10/25/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G865	List: ML20085G861 ML20085G866 ML20085G876
References
NUDOCS 8308290477
Download: ML20085G861 (3)

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PAf4T B Y 3:MH14 fir. Edson G. Case

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Acting Director of Licensing 2 O .'2# '(

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U.S. Atomic Energy Co=aission N Uashington, DC 20545 f*4

Dear Mr. Case:

TFlGESSEE VALLEY AUTHORITY - BROWNS FERRY HUCLEAR PLtJC UNIT 2 -

D00KET NO. 50-260 - FACILITY OPERATIHG LICENSE DPR ABNORMAL l OCCURREECEREPORTBFAO-50-260/7420W '

The enclosed report is to provide details concerning one.Grinn'll e shock and sway arrestor which was found on the recirculation system with an enpty reservoir on October 12, 1974, and ten Bergen-Faterson hydraulic shock and sucy arrestors which were found with an_

unacceptably lov amount of oil.present in the unit on October 17, 1974.

This report is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973. This event occurred on Brorns Ferry nuclear Plant unit 2 on October 17, 1974 Very truly yours, TEUNESSEE VALLEY AUTHORITY tMN

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P'" E. F. Thomas Director of Power Production

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m Mr. Hon::an C. Moseley, Director Region II Regulatoi/ Operations Offico, USAEC 230 Peachtree Street, mi., Suite 818 Atlanta, Georgia 30303 '

8308290477 741025

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f 9 9 ABIIOR:!AL OCCURRENCE REPORT ,

Report lio.: BFAO-50-260/74207 Report Date: October 25, 1974 Occurrence Date: October 17, 1974 Facility: Browns Ferry nuclear Plant unit 2 Identification of Occurrence During a planned inspection of hydraulic piping reatraints, one Grinnell shoch and sway arrestor was found on the recirculation system uith an empty reservoir on October 12, 1974; and the following Bergen-Paterson hydraulic shock and cuay arrestors were found with an unacceptably low amount of oil present in the unit on October 17, 1974:

1. Three arrestors on feedwater riser lines inside the drywell.

2. One arrestor on a main steenline inside the dryvell.

3. One arrestor on a control rod drive line inside the drywell.

4. .Tuo arrestors on the residual heat renoval lines outside the drywell.

5. One arrestor on the HPCI line outside the drywell.

6. One arrestor on the RCIC line outside the dryvell.

7 One arrestor on the condensate line outside the dryve'L1.

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

Descriution of Occurrence The depleted oil condition in the errestors was found during an inspection of Grinnell and Ecrgen-Paterson arrestors.

Desi;mation of Annarent Cause of Occurrence The apparent cause of loss of oil in the Grinnell shock arrestor was from nichs on two of the four. Chevron-type seals, which could have been a result of burra found on the piston rod end. The apparent cause of loss of oil in the Bergen-Paterson arrestors is twofold. The first cause can be attributed to the quality of worPanship during a recent rebuild program in which c11 software parts were replaced with ethylene-propylene software parts. In the reassembly phase of the rebuild program, the control valve assembly was irarcperly aligned with the main cylinder, permitting the oil to continuously leak out of the arrestor unit.

The second cause can be attributed to a poor design of the piston rod packing ring.

This packing ring contains an 0-ring in a U-cuo. This 0-ring stiffens the packing ring to such a degree that during the installation and operation of the packing L._.

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Designation of Annarent Cause of Occurrence (continued) l ring, the inner lip of the U-cun is subject to tearing pemittin;; oil to leak out of the arrestor unit. The packing ring nust be installed blind, preventing detection of cry tears on the inner lip of the packing ring until the arrestor unit is placed in service.

Ana3vais of Occu ronce 170 der. age to systems, coroonents, or structures was caused; no personnel in,iuries or croosures were involved; and no redicactive naterials were released as a result of loss of oil in these arrestor units.

Corrective Action on the Grinnell shock arrestor, the two nicked Cheron-type seals were replaced with 172 Grinnell-furnished U-cup, 0-ring seals; and the burrs were stoned off the piston rod. The Bergen-Paterson arrestor units that lost oil because of misaligned valve assemblies were properly aligned and reinstalled. Those units that lost oil because of tears on the packing ring lip were disasserfoled and new packing rings installed and reassenblad. These units were then returned to service. All the remaining arrestors were inspected and found to be in good .

condition. 1.11 arrestor units which had niceligned valve assemblies have been corrected, and this condition should not recur.

Failure Data This is the first inspection perforned on the Bergen-Paterson and Grinnell arrestors since nuclear haatup of this unit.

The Grinnell arrestors were rebuilt cad tested by the factory during February 1974 and installed in unit 2 during June 1974. The Bergen-Paterson arrestors were rebuilt during July 1974 using new seal natorial as a result of RO Bulletins Ilo. 73-3 and 73-4 Arrestors in unit 1 were inspected on April 8, 1974, and necessary corrections were rnAe to assure proper operation.

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