ML17252A450
| ML17252A450 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/27/1975 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | James Keppler NRC/RGN-III |
| References | |
| BBS Ltr. #556-75 50-249/75-33 | |
| Download: ML17252A450 (2) | |
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Comm ealth Edison One First anal Plaza, Chicago, Illinois
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Address Reply to: Post Office Box 767 Chicago, Illinois 60690
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BBS Ltr. #556-75 Dresden Nuclear Power Station R. R. #1 Morris, Illinois 6o450 A\\l8U8t -;:r, 1975 Mr. James G. Keppler, Regional Director Directorate of Regulatory Gperation-Region III
- u. s. Nuclear Reg}llatory Commission 799 Rooseveit Road Glen Ellyn, Illinois 6o1YT SUBJEX:Ts REPORT OF UNUSUAL EVENr Pm six:TION 6.6,C OF THE ~CAL SPmIFICmOllls LPCI VALVE 3-1501-5A THERMAL 'l'lUP References&
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Report Number:
50-249/75-33
- ',Report Dates AuguSt. 'Z'{, 1975.
Occurrence Date:.July 28; 1975 Paoilitys Dresden Nuclear Power Station, Morrie, Illinois IDENTIFICATION OF OCCURRBNCE The suction valve for the "A".LPCI pump, M0-3-1501-5A, trii>Ped twice on thermal overload *
. CONDITIONS PRIOR TO. OCCURRENCE Uni~ 3 was shutdown in a refueling outage. Surveillance testing of the LPCI system was in prQgress.
. DESCRIPl'ION OP. OCCURRmCE At 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br /> on July 28, 1975, the motor operator on valve 1501-SA tripped. on thermal overload* as the valve was being opened, The valve had Just been closed with the motor operator. Ai"ter opening, the valve could not be operated for approximately 40 minutes. As the valve was being closed. once more, the motor operator tripped again.
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- ~-~;~~*~ames G. ~eppl~.
,August 27, 1975 DESIGNATION* OP APPARml'*CAUSE OF OCCTJRRmCE (Component Failure)
The-*vaive.uiotOr tr:i.pi)ed. on -tbei'mal overioad.. -The 15 *:n~-lb. motor is* a limited-duty *type rated at2.95 amperes, with a *themal. overload trip setting of approximately 3.4 amps. *During valve operation the motor was drawing between 3.2 and *3.5 amps.
Without any load the motor was found to. draw r0ughl.y 2.8.
amps, or uearly the :tull-load current ratimg.
- Therefore, a defective motor appears to be th~ primary c*use of. the valve trips.
ANALYSIS OF OCCURRENCE The LPCI pump suction valves (1502-5A, -SB, -SC, and -5D) are in the open position during reactor operation and do not close in response to any group isolation signal.* Had valve 1501-5A failed in the closed poaitl,.on*during.reactor.
operation, the remaining three.LFCI pumps would have been.tully capable of proViding emergency core: cooling in the event of an accident. Plant personnel and the
. public were in no way endangered by this occurrence.
COBRitTIVE.ACTION The valve's motor was replaced with a similar type motor wbich draws:,; approximately 1.9 amps with no loa.d and 2.3 - 2.5 amps while operating the valve.
~e replacement motor*successfUlly cycled the valve several times.
PAILUBE DATA Valve 1501-5.A and other valves With suinlar motor operators have experienced several tripping problems in the past.* These problems are still under review.
BBS1EU3ismp*
File/NRC. *
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- Stephenson Superintendent