ML20086J289

AO 74-15:on 741015,drywell Purge Isolation Valves AO-3505 & AO-3520 Observed Cycling W/Valve Control Switch in Closed Position.Caused by Component Failure.Air Actuated two-way Valve on AO-3505 Reversed

ML20086J289
Person / Time
Site:	Peach Bottom
Issue date:	10/25/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086J293	List: ML20086J289 ML20086J303 ML20086J315
References
AO-74-15, NUDOCS 8401230556
Download: ML20086J289 (2)

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October 25, 1974 So-a1a Mr. A. Giambusso .

Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, DC 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. Walt Baunack, A.E.C. Region 1 Regulatory Operations Office on October 16, 1974.

Written notification was made to Mr. James P. O'Reilly, Region 1 Regulatory Operations Office on October 17, 1974. In accordance with Section 6.7.2.A of the Technical Specifications, Appendix A of DPR-56 for Uni t 3 Peach Bottom Atomic Power Station, the following report is being submi tted to the Di rectorate of Licensing as .an Abnormal Occurrence.

Reference:

License Number DPR-56 Technical Specification Reference 3.7.D.1 and 3.7.D.2 Report No.: 50-278-74-15 Report Date: October 25, 1974 Occurrence Date: October 15, 1974 -

Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identi fication of Occurrence:

Drywell purge isolation valves A0-3505 and A0-3520 were ob-served cycling (from the closed position to slightly off its seat to closed) with the valve control switch in the closed position.

Conditions Prior to Occurrence: -

Reactor shutdown. Primary system pressurized to approximately .

100 psig. Maximum power level achieved prior to occurrence was approxi-N mately 50%.

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Mr. A. Giambusso October 25, 1974 O Paga 2 .

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Description of Occurrence: '

The air actuated 2-way valves (which are part of the isolation valve pneumatic control) developed a small air leak which caused the I isolation valves to cycle.

Designation of Apparent Cause of Occurrence:

Component failure.

Analysis of Occurrence:

- Cycling of these valves could essentially cause a leak from

, the drywell to the secondary containment building. Because of the long interval between cycles, no significant leakage is believed to have occurred, y Corrective Action:

During the investigation it was discovered than an internal leak had developed in the air actuated 2-way valve from the sensing chamber (D-por t) through an 0-ring seal to the outlet port (C-por t) 1 which is connected to the valve operator (air to open) . The inlet port (A-port) is normally vented to atmosphere through the valve control solenoid valve. On a trial basis the air actuated 2-way valve on A0-3505 was reversed such that the C-port is now vented to atmos-phere through the control solenoid and the A-port is connected to the valve operator. This reversal will in no way affect the normal open/ shut operation of the air actuated two-way valve. During the seven day test period since the reversal, no valve cycling has occurred.

It is planned to make the same modification to all primary containment isolation valves which have the same control scheme (9 valves per plant).

Failure Data:

None. .

Very truly yours, f

M. J. Cooney Ass' t Gen' t Super intendent 4

Generation Division -f cc: J. P. O'Reilly

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Director, Region 1 ,

United States Atomic Energy Cannission-631 Park Avenue .

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King of_ Prussia, PA 19406 e