05000265/LER-1980-033-03, /03L-0:on 801201,RHR Sys II Supply from Diesel Generator Alarmed.Caused by Blown Fuse F11 Due to Grounded Wire in Unit 2 Diesel Generator to Bus 24-1 Circuit Breaker Auxiliary Contacts.Wire Repaired & Fuse Replaced

/03L-0:on 801201,RHR Sys II Supply from Diesel Generator Alarmed.Caused by Blown Fuse F11 Due to Grounded Wire in Unit 2 Diesel Generator to Bus 24-1 Circuit Breaker Auxiliary Contacts.Wire Repaired & Fuse Replaced

ML19340E133
Person / Time
Site:	Quad Cities
Issue date:	12/29/1980
From:	Dunesia Clark COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340E128	List: 05000265/LER-1980-033, Forwards LER 80-033/03L-0 05000265/LER-1980-033-03, /03L-0:on 801201,RHR Sys II Supply from Diesel Generator Alarmed.Caused by Blown Fuse F11 Due to Grounded Wire in Unit 2 Diesel Generator to Bus 24-1 Circuit Breaker Auxiliary Contacts.Wire Repaired & Fuse Replaced
References
LER-80-033-03L-02, LER-80-33-3L-2, NUDOCS 8101060482
Download: ML19340E133 (2)

LER-1980-033, /03L-0:on 801201,RHR Sys II Supply from Diesel Generator Alarmed.Caused by Blown Fuse F11 Due to Grounded Wire in Unit 2 Diesel Generator to Bus 24-1 Circuit Breaker Auxiliary Contacts.Wire Repaired & Fuse Replaced

Event date:
Report date:
2651980033R03 - NRC Website

text

NRC FORM 368 U.5. NUCLEAM MkGULAT UHY CCMMisblON (7 771 LICENSEE EVENT REPORT O.

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8 60 61 OOCKET NLMSER bd 69 EVENT CATE 14 75 REPORT QATE 30 EVENT DESCRIPTION AND FROBABLE CONSEQUENCES h t o 12 j l The "RHR System 11 Sucoly f rom Diesel Generator" annunciator alarmed for no apparent l

An investigation revealed that fuse Fil in panel 902-33 was blown, thus l

reason.

gojajl go;4j l making the relay logic circuit for RHR System 11 inoperable. The fuse was replaced l

but blew again on 12-2-80.

All components associated with the RHR System 11 logic l

,o,3; l l o !s 1 I ci rcuit could have been manually operated f rom the Control Room had the need arisen.

l lo l7) l RHR System I logic was also operable and unaffected by this occurrence.

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CAUSE DESCRIPTION ArJD CORRECTIVE ACTIONS 27 li 6 0 l l The cause of the blown fuse was a arounded wire in the Unit Two Diesel Generator 1

contacts. The wire was recaired and the fuse l

y I to Bus 24-1 ci rcui t breaker auxiliary it i,1 l replaced. All ci rcuits affected by this 'alown fuse were inspected and found l

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LER NUMBER: LER/R0 80-33/03L-0 11.

LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill.

FACILITY NAME: Unit Two IV.

DOCKET NUMBER: 050-265 V.

EVENT DESCRIPTION

At 2315 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.808575e-4 months <br /> on December 1,1980, Unit Two was operating steady state at 822 MWe and 2481 MWt.

At this time, the 'RHR System ll Supply from Emergency Diesel' annunciator alarmed for no apparent reason. An in-vestigation revealed that fuse F-ll in the 902-33 panel was blown, thus making the relay logic circuit for RHR System Il inoperable. The fuse was replaced and the alarm cleared and the relay logic circuit re-energized. On December 2, 1980, the alarm came up again. Work Request Q09578 was written to investigate the cause of the blown fuse.

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The consequences of this occurrence were minimal. The 'RHR System 11 Supply from Emergency Diesel' alarm was caused by the drop-out of relay 10A-KIB, which senses when the diesel generator circuit breaker closes into the emergency bus. With the blown fuse, the automatic initiation function of RHR System 11 was inhibited. The 'C' and 'D' RHR pumps and valves associated with these pumps could have been manually operated f rom the Control Room if necessary.

RHR System i logic was not affected by this occurrence.

Both Core Spray and all high pressure injection and cooling systems were operable.

Safe operation of the reactor was not affected as a result of this occurrence.

Vll. CAUSE:

The cause of the occurrence is designated as equipment failure. The blown fuse was caused by a grounded wire in the 4KV Unit Two Diesel Generator to Bus 24-1 circuit breaker auxiliary contacts. The wire had rubbed on the wiring harness inside the breaker cabinet and had worn off the wire insulation. The logic system was supplied by the 125 VDC battery.

Vill. CORRECTIVE ACTION:

The worn wire and blown fuse were replaced. The Control Room alarm cleared and the RHR relay logic circuit was re-energized. All circuits.

affected by this problem were inspected and operation of relay 10A-KIB was verified.