05000366/LER-1979-122-03, /03L-0:on 791117,while Reactor at Steady State of Operation,Dc Input Breaker to 2R44-S003 Tripped.Caused by Failure of Small Control Relay at LPCI Converter.Relay Replaced

/03L-0:on 791117,while Reactor at Steady State of Operation,Dc Input Breaker to 2R44-S003 Tripped.Caused by Failure of Small Control Relay at LPCI Converter.Relay Replaced

ML19291B953
Person / Time
Site:	Hatch
Issue date:	12/07/1979
From:	Nix R GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19291B952	List: 05000366/LER-1979-122, Forwards LER 79-122/03L-0 05000366/LER-1979-122-03, /03L-0:on 791117,while Reactor at Steady State of Operation,Dc Input Breaker to 2R44-S003 Tripped.Caused by Failure of Small Control Relay at LPCI Converter.Relay Replaced
References
LER-79-122-03L, LER-79-122-3L, NUDOCS 7912140448
Download: ML19291B953 (2)

LER-1979-122, /03L-0:on 791117,while Reactor at Steady State of Operation,Dc Input Breaker to 2R44-S003 Tripped.Caused by Failure of Small Control Relay at LPCI Converter.Relay Replaced

Event date:
Report date:
3661979122R03 - NRC Website

text

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td LVLNT DAIL J4 75 fit rOH T () AI L E0 Evttrr DESCmPTION AND PHO3 AGLE CONSCOUENCtS h O 7 l While the reactor was at a steady state of operation, the D. C.

Input lireaker to l

21<44-S003 ("B" LPCI Inverter) tripped.

This breaker is the priraary power suppy for ggl y o igj l the LPCI system valves, but the back-up systen was operable.

The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> LCO cOuld not be ract on the Inverter, so the reactor uas safely shutfown until the problem o

3 o c l could be solved. The safety of the general public was not af fected. This is a [g l non-repetitive event.

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40 41 42 43 44 47 CAu;E DESCNPTION AND CORHECTIVE ACTIONS h [ijoll The cause of the D.

C. input breaker to 2R44-S003 ("B" LPCI Inverter) vas due to the l

[ f ailure of a 'small cont rol relay at the LPCI Inverter.

The relay wris replaced and 1

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, l the Inverter tested and returned to service.

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Baxley, Georgia 31513 Reportable Occurrence Report No. 50-366/1979-122.

i Uhile the Unit II reactor was at normal operation, t h e 11. C.

input breaker

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to 21144-S003 ("g" I.PCI Inve rter) t ripped.

This breaker is the primary power source for the LPCI system valves and al though it trippeJ, the back-up power cource was available, f

The reason that the breaker tripped was due to the failure of a small control relay, located at the LPCI Inverter.

The failure of this relay caused the plant to be under a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> LCO.

The problen could not he identified and solved during this period so the reactor was safely shutdown f rom a power IcVel of 96% until the problem was corrected which was approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> later.

The relay was replaced and functionally tested for proper operation.

The Inverter was then returned to service and the unit was returned to service.

The failure of the control relay has not happened previcusly.

i The problem is applicable to the other unit in'that the same type relay exists on the Unit I LPCI Inverter.

These particular reiays are not used in this application in any other safety related system on either unit.

Unit one's relay on the LPCI Inverter was inspected for proper operation.

Inspection proved that the relay was operating snLisfactorily.

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