ML20010H816

LER 81-085/03L-0:on 810904,while Operating in Steady State Condition,B LPCI inverter,2R44-S003,tripped.Caused by Failure of Voltage Regulator on Gate Firing Module in Inverter Leg 7.Inverter Leg Replaced

ML20010H816
Person / Time
Site:	Hatch
Issue date:	09/15/1981
From:	Coggin C GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20010H805	List: ML20010H804 ML20010H816
References
LER-81-085-03L-01, LER-81-85-3L-1, NUDOCS 8109290319
Download: ML20010H816 (2)

Text

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7 8 60 EVENT DESCRIPTION AND PROS ABLE CONSEQUENCES h 10121 Mhile operating in a steadv state condition at 1711 MWt on Sentember 4. I O 3 11981, at 0445 CDT, "B" LPCI inverter, 2R44'-S003, tripped. This resulted l

[O i4; p.n an eight hour LCO per Tech. Spec. 3.8.2.1. LPCI iniection valve 2 Ell-l O s f017B is powered by Essential MCC 2R24-S018B and therefore, loop "B" was l iO is i pade ir,perable when the event caused it to become de-energized. 2R24- I m IS018B was transferred to the alternate supply. Plant operation and the I i O n i health and safety of the public were not affected: . Non-renetitive eventi 80 7 8 9 E CODE S BC E COMPONENT CODE SUB ODE SU E l0l9l lE lD l @ [ EJ @ [_A l @ l G l E l N lE l R l Aj@ y @ [_Z_j @

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, , ieg l was replaced with a new one, proper operation of the inverter veri- l g lEied and the inverter returned to service. The unit is in full compli- l ii ni pnce and no further reoorting is required. l 7 8 9 80 S  % POWER OTHER STATUS IS O Y DISCOVERY DESCRIPTION g [E J@ l 0 l 7 l 0 l@l NA l g gl Operator Observation l TlVITY C TENT ttELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE NA l l NA l U_La.] lZ_1 @ LZ_}@l PERSONNEL EXPOS ES NUMBER TvPE oESCRiPriON @

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LER #: 50-366/1981-085 Licensee: Georgia Power Company Facility Name: Edwin I. Ilatch Docket #: 50-366 Narrative Report for LER 50-366/1981-005 4

While operating in a steady state condition of 1711 MWt. (535 MWe) on September 4, 1981, at 0445 CDT, "B" LPCI inverter, 2R44-S003, tripped. This resulted in an eight hour LCO per Tech. Spec. 3.8.2.'1. The caused a loss of power to essential Motor Control Centertrip (MCC) 2R24-S018B. Since LPCI injection valve 2E11-F017B is powered by this MCC, tite "B" loop of LPCI was made inoperabl e. The alternate source for MCC 2R24-S018B was placed into service while investigation into the loss of the inverter was taking place. The cause of the inverter trip was determined to be a failure of the voltage regulator on the gate firing module located in inverter leg number seven. Initial investigations indicated that two diodes in that same inverter leg were also

, defective. For this reason the entire inverter Icg was replaced with a new one and the inverter was returned to service. Further troubleshooting of the defective inverter i leg revealed that the only defective component was the voltage regulator on the gate firing module. The failure of the voltage regulator is a non-repetitive occurrence and did not affect either of fhe inverters on Unit 1 or the remaining inverter on Unit 2.

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