ML20086Q324

Ao:On 730809,reactor Water clean-up Sys Pump Suction Outer Isolation Valve MO-12-18 Failed to Close.Caused by Valve Motor Armature Short to Rotor Shaft.Motor Replaced & Valve Manually Stroked to Ensure Mechanical Operability

ML20086Q324
Person / Time
Site:	Peach Bottom
Issue date:	08/17/1973
From:	Meyer R PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8402270510
Download: ML20086Q324 (2)

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PHILADELPHIA ELECTRIC COMPANY .

2301 MARKET STREET '

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August 17, 1973 S'\ '

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Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washincton, D. C. 205h5

Reference:

Peach Potten Atomic Power Station - Unit #2 Facility Operating License DPR-M Docket No. 50-277

Subject:

Abnormal Occurrence

Dear Mr. Giambusso:

DurinF the performance of a surveillance test en 8/9/73, the Reactor Water Clean-Up Systen pump suction outer isolation valve (MO-12-18) failed to close as required. This event was reported to Mr. Eldon Brunner, A.E.C.

Region 1 P.egulatory Operation Office on 8/9/73. In accordance with Section 6.7.7.A of the Technical Specification Appendix A of DPR-S for Unit #2 Peach Botton Atenic Power Station, this failure is being reported to the Directorate of Licensing as an Abnormal Occurrence.

Prior to the start of initial fuel loading, surveillance tests were per-forned on all systens recuired to ensure plant safety during this operation.

Additional surveillance tests applicable to reactor power operation were also perforned at this time. During the perfornance of one of the latter type tests, (Primary Containment Isolatien Systen Logic Functional) the Reactor Water Clean-Up System outer pump suction isolation valve failed to close as required. The inner pumn suction isolation valve (70-12-15) did close as required, thereby properly isolating the system. Since the system was prcperly isolated, the failure of this valve to close has no safety implication.

Investigation into the cause of the failure indicated that the valve motor armature had shorted to the rotor shaft which is grounded. The motor operates from an ungrounded 250 volt d.c. source. It was believed that at the time of failure an internittent extraneous d.c. system ground existed to provide a current return path f%r the armature ground in l MD-12-18. Further investications into the*cause of'the intermittent d.c.

ground has disclosed that the door catches en some motor control center -

l compartnents can contact the bare lugs on the control wire terminal strips.  ;

This condition is being corrected by relocatir)g these terninal stiips deeper 1 8402270510 730817 gDRADOCK 05000277

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into the conpartment to provide a minimum clearance of 3/h inches between the door catches and the terninal strips. There are a total of eight Cutler Hanner 20" deep Unitrol 250 volt d.c. notor control centers installed in Units #2 and #3. All cenpartments in these motor control centers required for Unit #2 operatien shall be inspected and have the proper clearances established by August 2h,1973. Compartments which control equipnent in Unit #3 and are not energized at this time shall be modified prior to energizing.

Following the replacement of the noter with an identical device, the valve was nanually stroked to ensure mechanical operability. Electrical check-out has not been concleted at this time since operation of the Reactor Water Clean-Up System is required to control reactor water level during the fuel loadinc program. A conclete functional check shall be made before the operability of the Prinary Containment Isolation System is required.

Since this is the first failure of a d.c. valve in this manner, no further action is planned. Verbal instructions have been given to shift personnel to closely nonitor the d.c. systen ground annunciators, particularly during operation of d.c. notors.

Very truly yours,

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R. D. Meyer, Gene al Superintendent Generation Division Electrical Production Department 4

PDM:jfb cc. Mr. James P. O'Reilly Director, Regulatory Operations, Eegion 1 United States Atenic Energy Conmission Directorate of Regulatory Operations, Region 1 631 Park Avenue King of Prussia, Pennsylvania 19h06 y

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