ML20086H691

Telecopy AO 75-42:on 750716,TIP Machine Ball Valve C Failed to Close.Caused by Failure of Shield Limit Switch.Switch Dismantled,Inspected,Found to Be Clean & Free of Binding, Reassembled & Readjusted for More Positive Switch Operation

ML20086H691
Person / Time
Site:	Peach Bottom
Issue date:	07/17/1975
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086H694	List: ML20086H691 ML20086H696
References
AO-75-42, NUDOCS 8401190565
Download: ML20086H691 (1)

Text

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. PHILADELPHI A ELECTRIC C0!!PAdY Peach Bottom Atomic Power Station Del ~ta, Pennsylvania 1731h July 17, 1975 Hr. Jamen P. O'Reilly, Director O f fi c e of Inspection and Enforcement, ggy

' United States Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania- 19h06

Subject:

Abnornni Occurrence Ph-Hour Notification Confirming W. T. Ullrich's conversation with Mr. Walt Baunack (on site),

Region 1, United States Hucicar Regulatory Commission on July 17, 1975 License Number DPR-56

Reference:

, Technical Speci fication

Reference:

4.7.D Repor.t No.: 50-278-75 42 Report Date: July 17, 1975 Occurrence Date: July 16, 1975 -

Facility: Peach Botton Atomic Power Station R.D. 1 Delta, Pennsylvania 1731h

, Identi fi c at i on of Occurrence:

Failure of the "C" TIP machine ball valve to close.

Conditions Prior to Occurrence:

. Unit 3 at 50% power.

Description of Occurrence:

During routine operation of the TIP machines, the "C" detector failed to stop at the shield limit and close the ball valve as it was being withdrawn to the shield chamber.

Designation of Apparent Cause of Occurrence:

The chield limit switch, which controls detector travel and ball valve

, operation, failed to operate when the detector reached the 'in-shield' position. This allowed the detector to continue its withdrawal until it was manually stopped.

Analysis of Occurrence: .

The failure of the limit switch to halt'the withdrawal and close the ball valve vaa immediately observed and corrected by suitching to the manual

, mode of operation and stopping the machi,ne. The ability to close the ball valve by turning the machine off (de-energi:c to close) was verified and

' would have been available i f .r eq'ui red . Therefore, there are no safety

+

implications to this occurrence.

Corrective Action:

The detector was returned to its in-phield position. The machine van de ,

energized, and the ball valve was verified to be closed. The shield limit switch mechanism was dismantled, inspected, found to be cican and free of binding, reassembled, and readjusted for more positive switch operation.

, The switch was then successfully tested several times.

. Failure Data:

Previous failures of this type reported as 50-278-75-31 and 50-278-75-34.

, Very truly yours, fWNWho W. T. Ullrich. Superintendent

• b 8401190565 750717

. PDR ADOCK 0500027y .

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