ML20086K970

AO 74-25:on 740512,containment Isolation Ball Valve for Traversing in-core Probe Machine 4 Failed to Shut.Caused by Sticking or Binding in Isolation Valve Solenoid Mechanism. Valve Solenoid Operating Mechanism Disassembled

ML20086K970
Person / Time
Site:	Peach Bottom
Issue date:	05/22/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086K972	List: ML20086K970 ML20086K979
References
AO-74-25, NUDOCS 8402070097
Download: ML20086K970 (2)

Text

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May 22, 1974 )e Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing kashington, DC 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. R. A. Feil, A.E.C.

4 Region I Regulatory Operations Office on May 13, 1974. Written notifica-tion was made to Mr. James P. O'Reilly, Region I Regulatory Operations 1 _0ffice on May 13, 1974. In accordance with Section 6.7.2.A of the iecnnicas spec 1 rications, appenat x a or UPN-44 tor Uni t 2 Peach Bottom Atomic Power Station, the following report is being submitted .to the Directorate of Licensing as an Abnormal Occurrence.

4

Reference:

License Number DPR l4, i Amendment Number 1 Technical Specification 3.7.0 i

Report No.: 50-277-74-25 Report Date: May 22, 1974 Occurrence Date: May 12, 1974 Facility: Peach Bottom Atomic Power Station R. D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

The containment isolation ball valve for the Traversing In-Core Probe (TIP) machine No. 4 failed to shut.

Conditions Prior to Occurrence: - g u: q

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The reactor was critical at about 75% power, 990 psig. Fuel pre-conditioning operation was in progress. 7 ti 8402070097 740522 i 9, PDR ADOCK 050v0277 S sdh IV -

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Mr. A. Giambusso f-s May 22, 1974 (,) g-)S g_ Page 2 Description of Occurrence:

Af ter operation of the No. 4 TIP machine, the operator observed that the isolation ball valve did not shut automatically. The operator unsuccessfully attempted to shut the valve using the remote manual switch.

Designation of Aoparent Cause of Occurrence:

Sticking or binding in the isolation valve solenoid mechanism.

Analysis of Occurrence:

This incident hat minimal safety implications. The control room operators verified the continuity of the shear valve for the No. 4 TIP machine. This valve serves as back-up to the ball valve. All other TIP machines were retracted into their shields and operability of their isolation valves was verified. Shift Supervision instructed control room personnel to be prepared to actuate the shear valve should conditions arise which require the ball valve to be shut automatically.

Corrective Actien:

The power feed was removed from the valve. This valve fails shut on a l os s of power . Mechanical snock was applied to the solenoid sectier cf th: 7:!ve. The TI." dete:: r .:: th:r. rctr. ted i;.tc its M.iclJ after which the valve shut automatically. Several manual operations of the valve, using the remote manual switch, proved that the valve closing operation was sluggish. With the valve in the shut position, the power feed was removed and tagged from the No. 4 TIP machine thereby preventing a re-opening of the valve.

The valve solenoid operating mechanism was disassembled to per-mit manual operation of the ball valve. The operating mechanism was man-ually moved through its full stroke with no apparent binding or sticking.

The tension on the valve operator closing spring was adjusted to provide addit ional c losing force. The valve was reassembled and tested satis-f actorily by operation fran the remcte manual switch. Numerous opera-tions of the valve proved that the closing stroke was consistently within 1 second of the switch operation.

Failure Data:

None.

Very truly yours,

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M . ~ J . C ooney '

l Ass't Gen'l Superintendent Generation Division l cc: Mr. J. P. 0'Reilly .

! Director, Region i United States Atomic Energy Ccmmission 631 Park Avenue King of Prussia, PA' 19406

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