ML20090E491

AO 50-237/75-42:on 750829,diesel Generator Cooling Water Pump Tripped,Followed by Diesel Generator Trip on High Temp. Cause Not Established.Investigation of Cooling Water Pump & Associated Breakers Continuing

ML20090E491
Person / Time
Site:	Dresden
Issue date:	09/08/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20090E494	List: ML20090E491 ML20090E495
References
595-75, 9853, AO-50-237-75-42, NUDOCS 8304010010
Download: ML20090E491 (2)

Text

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n Commonwealth Edison v

".,3 .( O \ One First N"' Ni Pina. Chicago, Illinois Q Addrgss RTesto: Pcst Office Box 767 Chicig. lilinois 60690 o>

BBS Ltr. #595 75 Dresden Nuclear Power Statiotta' .Q R. R. #1 ,O f Morris, Illinois 't l

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%t 1 Mr. James G. Keppler, Regional Director Directorate of Regulatory Operation-Region III

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\M.o 'h' i U. S. Nuclear Regulatory Comission 4 799 Roosevelt Road W-Olen Ellyn, Illinois

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SUBJECT:

REPORT OF AENORMA.L OCCURRENCE PER SH: TION 6.6.A 0F THE TECHNICAL SPECIFICATIONS f UNIT 2/3 DIESEL GSTERATOR COOLING WATER PUMP TRIP

References:

1) Regulatory Guide 1.16 Rev. 1 Appendix A 1

2) Notification of Region III of U. S. Nuclear Regulatory Comission I Telephone: P. Johnson, 1215 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.623075e-4 months <br /> on August 30, 1975 Telegram: J. Kepplei, 1:iS5 hours on September 2, 1975 i

3) Drawing Number M-355, 12E2351B I

Report Number: 50-237/75-42 .

Report Date September 8, 1975 j Occurrence Date

August 29, 1975 j Facility: Dresden Nuclear Power Station, Morris, Illinois f

I IDENTIFICATION OF OCCURRENCE ,

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The Unit 2/3 diesel generator cooling water pump tripped. The 2/3 diesel generator itself subsequently tripped on high-temperature.

CONDITIONS PRIOR TO OCCURRENCE Unit-2 was at a steady-state power level of 2463 MWt and 793 MWe. Unit-3 was in the shutdown mode for'a refueling outage. A deluge fire test of the Unit-3 reserve auxiliary transformer was being performed when the incident occurred.

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i DESCRIPPION OP OCCURRDiCE l

f At approximately 1210 hours0.014 days <br />0.336 hours <br />0.002 weeks <br />4.60405e-4 months <br /> on August 29, 1975, the' Unit 2/3 diesel generator was started and loaded to about 2MW. At 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br /> the diesel tripped on high-temperature. Alazine indicated a ' cooling water pump failure.

4 The cooling water pump is normally fed Lum bus 28-3, automatically transferring i to bun 38-3 in the event of a breaker trip. The breakers on both buses were i found tripped.

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DESIGNATION OF APPARENT CAUSE OF OCCURRENCE l

i No definite cause for the pump trip can be established at this time. An investi-j s'ation is undeiway to deterinine why both breakers tripped.

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j ANALYSIS OF OCCURRENCE The Unit-2 diesel generator and all low-pressure emergency core cooling systems on Unit-2 were 1:rediately proven operable. Unit-3 was in the shutdown mode l with it's diesel generator operating at the time of the occurrence. Adequate emergency power was available at all times to supply ECCS in accident conditions. The health and safety of plant personnel and the public were not

! threatened by this occurrence.

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j CORRECTIVE ACTION .

I i The cooling water pump was inspected inanediately following the trip and was

found to be cool with no evidence of being air-bound. The pump was re-started i and appeared ,to operate smoothly. On September 5, 1975,~after running for j a period of approximately two hours, the pump tripped again.

j Investigation of the 2/3 cooling water pump and its associated breakers will

' be contia.ued. The Unit-2 and -3 diesel generator cooling water pumps have l

proven operability by operating relatively long periods of time without difficulty.

t Further corrective action will be taken when a specific cause has been identified.

j- A follow-up letter will be submitted at that time.

! FAILURE DATA j The cooling water pumps have never experienced problems of this natura oefore. -

f [B.B.Stephenson i Superintendent l BBS:JBM:smp .

l l File /NRC 9

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