ML17252A935
| ML17252A935 | |
| Person / Time | |
|---|---|
| Site: | Dresden  (DPR-019, DPR-025) |
| Issue date: | 12/21/1973 |
| From: | Worden W Commonwealth Edison Co |
| To: | O'Leary J US Atomic Energy Commission (AEC) |
| References | |
| WPW Ltr #930-73 | |
| Download: ML17252A935 (2) | |
Text
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~lltBfyi Common.Ith Edison I.*
-~- c One First Nat al Plaza, Chicag9, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690
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- ~ *. WiW Ltr #930-73 Dresden Nuclear Power Station R~ R. #1
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DOCKETED U$AEC uEC ?71973..,.. s
<o Mr. J. F. 0 'Leary, Di.rector Directorate** of Licensing U. S. Atomic Energy Commission Washington, D. C. 20545 Morris, Illinois 60450 December 21, 1973
SUBJECT:
LICENSE DPR-2 DRF.SDEN NUCLEAR POWER STATION UNIT 3,
REPORT OF NORMAL OCCURRENCE PER S~TION ** B.l.a OF THE TECHNICAL SPECIFICATIONS UNIT 3 DIESEL GENERATOR COOLING WATER PUMP TRIP
References:
l) Notification of Region *III of AEC Regulatory Operations Telephone:
Telegram:
Mr *. *Fiorelli, 1400 hour~ on December 14, 197 3 Mr. J. Keppler, 1240 hours0.0144 days <br />0.344 hours <br />0.00205 weeks <br />4.7182e-4 months <br /> on December 14, 1973
- 2) Dwgs:
P & ID M-355
Dear Mr. O'Leary:
This letter is to report a condition relating to the operation of the linit at about 0005 ho\\irs ori December 14*, 1973. At this 'time, the Unit 3 diesel generator cooling water pump bre.aker tripped, causing the Unit 3 diesel generator to trip on high temperature.
This malfunction is contrary to section 3.5.i.l of the Technical Specifications which requires that the reactor be in the cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the diesel generator is inoperable and it cannot be verified that all of the low pressure core cooling and containment cooling subsystems are operable.
PROBLEli
.At the time 'of the-occurrence, the reactor power.was 690 MWe (2229 MWt).
The deviation occurred when the operator attempted to*
verify the operability of the diesel generator following the semi-annual maintenance inspection.
The Unit 3 diesel genera~or was started at 2310 hours0.0267 days <br />0.642 hours <br />0.00382 weeks <br />8.78955e-4 months <br /> on December 13, 1973, to verify operability folloWing the semi-annual maintenance inspection. It tripped at 2340 hours0.0271 days <br />0.65 hours <br />0.00387 weeks <br />8.9037e-4 months <br /> the same day on high temperature. Shift personnel conducted,an immediate investigation, which revealed that the diesel generator cooling water pump bre8.ker had tripped.
Inspection of the breaker and the cooling water pump revealed nothing abnonnal.
Therefore, the breaker was reset and the operator re-started the Unit 3 diesel generator at 0029 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> on December 14, 1973. Two minutes later, at 0031 hours3.587963e-4 days <br />0.00861 hours <br />5.125661e-5 weeks <br />1.17955e-5 months <br />, the cooling water pump breaker tripped and the 1Qn.a..2,.
operator shutdown the diesel generator. Work request #7623 was issued to
Mr. J. F. O'Leary e **e*
December 21, 1973
~-**.~
the Electrical.Maintenance Department to ir!v~stigate and repair the.
-~- _,.._problem.
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INVESTIGATION The Electrical Maintenance Department inspected the diesel generator cooling water pump breaker and the related electrical systems; but could find nothing that would have caused the problem. At about 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the Unit 3 diesel generator was again started, but tripped on high temperature approximately 20 minutes later. Following the unsuccessful trial run, the diesel generator cooling water pump and lines were meggered and tested satisfactorily. It was decided at this time that the breaker was defective and the decision was made to replace the breaker.
CORRECTIVE ACTION The cooling water pump *breaker was replaced with an identical 480 volt, 150 ampere breaker GE model TFJ236150 on *December 15, 1973.
Following replacement -of the breaker, the Unit 3 diesel generator was started and a one hour* trial run was successfully completed at about 1130 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.29965e-4 months <br /> on* December 15, 1973.
The defective breaker was tested, idisassembled and inspected on site by Gene.ral.Electric Company personnel.
The illspection _revealed no physical *damage to the.breaker. or µiissing parts. The. test revealed **
that the breaker wouid hold 100 amps for only* a few minutes before tripping and.tripped out when a surge of between 100.and 110 amps was applied.
It was concluded that the breaker was defective. In order to determine the cause of the breaker failure it will be returned to the factory for analysis_.
EVALUATION The safety of the public and the plant were not jeopardized by this incident because all of the systems required to be operable when the Unit 3 diesel generator is inoperable were tested and verified operable, ip accordance wl.th Technieal Specification 3.5.F.l.
SJ.nee the cooling water pump and the associated breaker were recently installed in October as a station modification, no problems have been' experienced with this breaker or like breakers on similar systems during preoperation:_.or monthly testing.
Analysis of the breaker at the factory should identify the specific defect and help to preclude recurrence of similar defects in breakers manufactured in the future.
The incident posed no problem that justify limiting continued operation of Unit 3.
WPWals Sincerely,
\\JJ.~.~~
W. P. Worden Superintendent