ML20086J431

AO 74-10:on 741003,improper Valving Found on One Drywell High Pressure Scram Switch.Cause Not Determined.In Restoring Sys After Most Recent Testing,Technicians May Have Mistakenly Checked & Verified Neighboring Valve

ML20086J431
Person / Time
Site:	Peach Bottom
Issue date:	10/13/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-74-10, NUDOCS 8401230672
Download: ML20086J431 (2)

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' PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET PHILADELPHIA PA.19101 121518 41-4ooo .

October 13, 1974

.- - /3 Mr. A. Giambusso .s Deputy Director of Reactor Projects

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United States Atomic Energy Commission '

Directorate of Licensing ,

lil Washington, DC 20545 . 21!

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Dear Mr. Giambusso:

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Subject:

Abnormal Occurrence -

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The following occurrence was reported to Mr. Walt Baunack, A.E.C.

Region 1 Regulatory Operations Office on October 4,1974. Written noti-fication was made to Mr. James P. O'Reilly, Region 1 Regulatory Opera-tions Office on October 4, 1974. In accordance with Section 6.7 2.A of the Technical Specifications, Appendix A of DPR-56 for Unit 3 Peach Bottom Atomic Pover Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence:

Reference:

License Number DPR.56 Technical Specification

Reference:

Table 3 1.1 Report No.: 50-278-74-10 Report Date: October 13, 1974 Occurrence Date: October 3, 1974 Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

Improper valving of one drywell high pressure scram switch.

Conditions Prior to Occurrence:

The reactor had been shutdown 16 days for a maintenance outage.

' Description of Occurrence:

During a routine instrument surveillance test, the local iso--

lation valve for drywell high pressure scram switch PS-3-5-12c was found to be in the shut position. Isolation of the deviceEfrom i:s sensing line renders it'inoperabic.

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, Mr. A. Giambuss ( ) l October 13, 1974 Page 2 o  ;

Designation of Apparent Cause of Occurrence:

An intensive investigation has been conducted in order to explain this occurrence. Documentation associated with other work has: '

been reviewed to determine if the valve could have been mistakenly -

operated. The instrument technicians who performed the previous sur-veillance tests were contacted and procedures reviewed and verified.

No positive explanation was determined. It is believed, however, that in restoring the system after its most recent testing the instrument technicians may have checked and verified a neighboring valve by mis-take, thereby f ailing to properly valve this instrument into service.

Analysis of Occurrence:

This device is connected in a one-out-of-two twice logic configuratien. Inoperability of one device does not prevent the pro-tective system from performing its intended function. The other devices monitoring drywall pressure were checked and their valves found in the proper position. For the above reasons, this occurrence is of minimal safety significance.

Failure Data:

One o . cr occurrence of this type was previously reported as an Abnormal Occ. rence 50-277-74-36.

Very truly yours, g Ly3 .C [

t. J. Cooney Ass t Gen ' l Super intendent Generation Division cc: Mr. J. P. O'Reilly Director, Region 1 United States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406

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