ML20086J078

AO 75-4:on 750107,two Primary Containment Isolation Valves Failed to Close.Caused by Dirt in Instrument Air Supply Piping & Improper Assembly of Solenoid Valve.Valve AO-3-20-83 Repaired by Straigntening Misaligned Follower

ML20086J078
Person / Time
Site:	Peach Bottom
Issue date:	01/17/1975
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A Office of Nuclear Reactor Regulation
References
AO-75-4, NUDOCS 8401230114
Download: ML20086J078 (2)

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PHILADELPHIA ELECTRIC COMPANY _.

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' January 17, 1975 -

,Q U  ; V:v' Mr. A. Giambusso Q_% '

Deputy Director of Reactor Projects x!.

United States Atomic Energy Commi ssion Directorate of Licensing .

Washi n gton, D.C. 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. Walt Baunack, A.E.C. Region 1 Regulatory Cperations Office on January 8,1975.

Written notification was made to Mr. James P. O'Reilly, Region 1 Regulatory Operations Of fice on January 8,1975. In accordance with Section 6.7.2.A of the Technical Speci fications, Appendix A of DPR-56 for Unit 3 Peach Bottom Atomic Power Station, the following report is being .eubmi tted to the Di rectorate of Licensing as an Abnormal occurrence.

Reference:

License Number DPR Technical Specification Ceferences:

3.7.0 and 4.7.D Report No.: 50-278-75-4 Report Date: January 17, 1975 Occurrence Date: Janua ry '7, 1975 Faci li ty: Peach Bottom Atomic Power Station R. D. #1, Delta, Pennsylvania 17314 Identi fi ca tion of Occurrence:_

Failure of two primary containment isolation valves to close.

Conditions Prior to Occurrence:

Reactor shutdown. Primary coolant temperature approximately 1500F.-

Description of Occurrence:

During the performance of the PCIS logic system functional, the drywell floor drain outboard ' isolation valve (AO-3-20-83) and the instrurrent ni trogen supply valve to the torus (AO-3968)- failed to close on a Group 11 and Group III isolation signal. Both valves also' failed to close when operating from their remote control switch.

8401230124 750117 gDRADOCK 05000278 PDR ~

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Mr. A. Giambusso

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January 17, 1975 . . . Page 2 Designation of Apparent Cause of Occurrence:

Small amounts of dirt in the instrument air supply piping and improper assembly of solenoid valve.

Analysis of the Occurrence:

During the test, the inner drywell floor drain isolation valve operated properly to isolate ~the line. The instrument ni trogen supply line to the torus contains two check valves in series wi th the isolation valve which failed to close. These check valves would pre-vent leakage from the torus to the reactor building. The failures described above have minimal safety implications.

Corrective Action:

A0-3-20-83 was repaired by straightening a misaligned pack-ing follower. The solenoid valve was also disassembled, inspected, and operated on a test stand. Following reassembly, valve operation was satisfactory.

A0-3968 was disassembled and inspected. No reason for the failure was identi fied. Following reassembly, the valve opera ted p rope rl y. To complete the investigation, an absolute filter was placed on the air line supplying air to this solenoid valve. When removed, the absolute filter indicated some signr, of di rt accumulation.

The instrument air line was blown to atmosphere until no addi tional signs of dirt were noted. The valve was functionally tested successfully.

Failure Data:

Similar occurrences were reported as Abnormal Occurrence Report Numbers A0-50-277-74-7, A0-50-278-74-26, and A0-278-74-39.

Very 'truly yours,

Yl .' . 'P L* Jgg H. J.'Cooney Asst. Genl . Supt.

' Generation Division cc: Mr. Jaces P. O'Reilly Director, Region 1 United States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406

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