05000266/LER-1980-004-03, /03L-0:on 800409,w/plant at Normal Steady State, Emergency Diesel Generator Failed to Start During Routine Surveillance Test.Second Attempt Unsuccessful.Caused by Broken Vane in Starting Air Motor.Air Motor Replaced

/03L-0:on 800409,w/plant at Normal Steady State, Emergency Diesel Generator Failed to Start During Routine Surveillance Test.Second Attempt Unsuccessful.Caused by Broken Vane in Starting Air Motor.Air Motor Replaced

ML19309G412
Person / Time
Site:	Point Beach
Issue date:	04/25/1980
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19309G399	List: 05000266/LER-1980-004, Forwards LER 80-004/03L-0 05000266/LER-1980-004-03, /03L-0:on 800409,w/plant at Normal Steady State, Emergency Diesel Generator Failed to Start During Routine Surveillance Test.Second Attempt Unsuccessful.Caused by Broken Vane in Starting Air Motor.Air Motor Replaced
References
LER-80-004-03L, LER-80-4-3L, NUDOCS 8005060263
Download: ML19309G412 (3)

LER-1980-004, /03L-0:on 800409,w/plant at Normal Steady State, Emergency Diesel Generator Failed to Start During Routine Surveillance Test.Second Attempt Unsuccessful.Caused by Broken Vane in Starting Air Motor.Air Motor Replaced

Event date:
Report date:
2661980004R03 - NRC Website

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EVENT DESCRIPTION AND,RO8A8tE CONSEQUENCES h O 2 lAt 0422 on 4"9-80, with the plant at normal steady state, the emergency I l Diesel generator failed to start during a routine surveillance test.

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ATTACHMENT TO LICENSEE EVENT REPORT NO. 80-004/03L-0 Wisconsin Electric Power Company Point Beach Nuclear Plant Unit 1 Docket No. 50-266 l

On April 9, 1980, at 0422 hours0.00488 days <br />0.117 hours <br />6.977513e-4 weeks <br />1.60571e-4 months <br /> while performing a routine surveillance test the 4D emergency diesel generator failed to start, and an " emergency diesel G02 starting circuit disabled" alarm annunciated.

The operator immediately went to stop on the diesel generator control switch after receiving the alarm, which initiated the diesel shut-down timer.

The alarm cleared when reset and correct system lineup was verified by the Shift Supervisor.

A second attempt to start the diesel was made at 0435 hours0.00503 days <br />0.121 hours <br />7.19246e-4 weeks <br />1.655175e-4 months <br /> and the diesel again failed to start.

Failure of the diesel to start this time, however, could possibly be attributed to the shut-down sequence initiated by the operator after the first start failure.

When the operator turned the diesel control switch to stop he initiated the shut-down sequence which consists of reducing diesel speed to idle for 11 1/2 minutes followed by a three and one-half minute complete shut-down period.

The diesel cannot be manually started except for a fast start during the complete shut-down phase, although if the diesel were in automatic a start signal would override the shut-down sequence.

Upon receiving the second start failure, the 4D diesel was declared inoperable for maintenance, and operability of the redundant 3D emergency diesel generator was verified at 0436 hours0.00505 days <br />0.121 hours <br />7.208995e-4 weeks <br />1.65898e-4 months <br /> on April 9.

This placed the plant in a degraded mode of operation allowed by Technical Specification 15.3.7.B.l.e.

When inspected to determine the problem, a faulty relt.y in the "not in automatic" alarm circuit was discovered.

Failure of this relay should not have prevented a diesel start however.

Although after replacement of the relay, the diesel functioned properly during a subsequent operability verification test.

The 4D emergency diesel generator was returned to service at 1035 hours0.012 days <br />0.288 hours <br />0.00171 weeks <br />3.938175e-4 months <br /> on April 9.

On April 16 additional testing of the diesel was conducted to try and determine the exact cause of the April 9 start failure.

The relay was removed and a diesel start was attempted.

The diesel failed to start on a manual remote start signal but did start on a fast start signal.

The relay was installed again and a diesel start was again attempted.

The diesel failed to start again on a manual start.

This indicated that there was another problem with the diesel.

The diesel had been in Start System 2 during all these attempts and it was postulated that the problem may be with Start System 2.

The start system selector switch was switched to-System 1 and the diesel started on a manual remote signal.

. An investigation of the No. 2 air start system identified a broken vane in one of the air starting motors.

The air motor was replaced and operability of the diesel was verified on April 16.

The diesel is equipped with two independent air starting systems, each of which is capable of starting the diesel.

During a manual remote start, one of the start systems is selected and the other system does not function.

During an automatic start, however, the system selected will function first and the second system will kick in automatically if the diesel does not start within a specific time.

This fact was verified when the diesel started upon a fast start signal with the defectiva motor still installed and Start System 2 selected.

Thus, the diesel would have started during an actual loss of off-site power.

Routine surveillance testing of each emergency diesel generator is performed biweekly.

The priority air start system selected is alternated monthly.

Removal of one emergency diesel generator from service because of its failure to start placed the plant in a degraded mode of operation allowed by Technical Specification 15.3.7.B.l.e and reportable in accordance with Technical Specification 15.6.9.2.B.2.

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