05000321/LER-1981-026-01, /01T-0:on 810405,emergency Diesel Circuit Breakers Failed to Auto Close Following Loss of Sys Pressure Test Sequence.Caused by Undervoltage Relays Failure to Deactivate Upon Loss of Power.Relays Checked

/01T-0:on 810405,emergency Diesel Circuit Breakers Failed to Auto Close Following Loss of Sys Pressure Test Sequence.Caused by Undervoltage Relays Failure to Deactivate Upon Loss of Power.Relays Checked

ML20003F786
Person / Time
Site:	Hatch
Issue date:	04/16/1981
From:	Coggin C GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20003F785	List:
References
LER-81-026-01T, LER-81-26-1T, NUDOCS 8104230586
Download: ML20003F786 (2)

LER-1981-026, /01T-0:on 810405,emergency Diesel Circuit Breakers Failed to Auto Close Following Loss of Sys Pressure Test Sequence.Caused by Undervoltage Relays Failure to Deactivate Upon Loss of Power.Relays Checked

Event date:
Report date:
3211981026R01 - NRC Website

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EVErdiOATE 74 75 HE PORT OATE 80 EVENT DESC7ilPTION AND PRODABLE CONSEQUENCES h 10171 111ni t 1 vtas shutdown for a refueling / torus modi fi ca ti on outage.

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I 1013]Iwas o_peratina at rated nower.

While oerforming a Unit 1 nrotective relavl 10141lbreaker trip test procedure, the emergency diesel circuit breakers 1

101s1 [ failed to AUTO close following an LOSP test sequence.

The Unit 1 emer-1 IOlciIgency busses remained deenergized until normal power wa<: manually re-I lOl71lstored.

An LCo was declared ner Unit 2 Tech Specs 3/4.6.6.1.

The eventl 10181 lis nonrepetitive.

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3J 34 35 36 31 40 43 42 43 44 47 CAuSE DEOCRIPTION AND CORRECTIVE ACTIONS h it101(Cause was traced to undervoltage relays (monitorino the standbv offsite I 11 111 Ifeeder) f ailure to deastivate uoon loss of power.

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The test was reoerformed. and the diesel I

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The undervo1tane relav in its pres-I

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LER #:

50-321/1981-026 Licensec:

Georgia Power Company Facility Name:

Edwin I. Ilatch i

Docket #:

50-321 4

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Narrative

Report for LER 50-321/1981-026 On Sunday morning, 4-5-81, while Unit 1 was shutdown for a refueling / torus modification outage and Unit 2 was operating at rated power, maintenance procedure PROTECTIVE RELAY-BREAKER TRIP TEST,ilNP-1-6950, was in progress.

An offsite power feed trip test sequence was performed as follows:

Normal startup transformer ID wa s locked out by tripping its protective relaying.

Diesels started and standby startup transformer 1C assumed caergency bus loads.

Standby startup transformer 1C was locked out by tripping its protective relaying.

Diesel breakers did not AUTO close.

The emergency busses remained deenergized until normal startup power was restored.

The Unit 1 diesels were declared inop, and Unit 2 entered into an LCO per Tech Specs 3/4.6.6.1.

Due to a common refueling floor, Unit 2 operation requires Unit 1 secondary containment integrity which is subdefined by standby gas treatment operab-ility dependent upon diesel emergency power operability.

This event is nonrepetitive.

There were no effects upon pu.blic health and safety.

The dicsc1 breakers failed to AUTO close because the LOSP lockout switch did not operate which depends upon emergency bus and standby startup transformer 1C feeder undervoltage relay logic..

The caergency bus undervoltage logic operated propely by virture of the dicsc1 AUTO start.

The cause of LOSP lockout misoperation was traced to two standby startup transformer 1C undervoltage

relays, Westinghouse disk induction type CV-7.

A first-hand observation revealed the disk failed to rotate upon loss of fe,eder PT voltage and break the normally energized (1 out of 2) logic which contributes to make up the LOSP lockout trip.

The relays were removed from the casings and visually inspected for damage and the presence of metal filings and dirt, then checked for proper operation and returned to an operabic status.

The test IINP-1-6950 was reperformed and the dicsc1 breakers AUTO closed successfully.

The relays were checked for disk movement upon loss of PT voltage the next day for both units and found working properly.

The relay in its present application is under investigation.

An update report will be submitted.

P00R ORIGINAL