PNO-III-88-018A, on 880309,technician Error Resulted in Both Recirculation Pumps Tripping Followed by Isolation of Steam Supply to Feedwater Heaters.Reactor Tripped When Power Spike Reached 118% Setpoint on High Aprm.No Fuel Damage Occurred

PNO-III-88-018A:on 880309,technician Error Resulted in Both Recirculation Pumps Tripping Followed by Isolation of Steam Supply to Feedwater Heaters.Reactor Tripped When Power Spike Reached 118% Setpoint on High Aprm.No Fuel Damage Occurred

ML20150C890
Person / Time
Site:	LaSalle
Issue date:	03/17/1988
From:	Forney W, Ring M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-88-018A, PNO-III-88-18A, NUDOCS 8803220388
Download: ML20150C890 (1)

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PRELIN1 RY NOTIFICATION 0F EVENT OR UNUSUAL OCCURRENCE--PNO-III-88-18A Date March 17, 1988 This prdrimirfary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III staff on this date.

Facility: Commonwealth Edison Company Licensee Emergency Classification: i LaSalle 2 Notification of an Unusual Event Marseilles, IL 61341 Alert l Site Area Emergency Docket No. 50-374 General Emergency X Not Applicable

Subject:

REACTOR SCRAM----(UPDATE)

On March 16, 1988, an NRC Augmented Inspection Team (AIT) was dispatched to the plant to investigate circumstances surrounding the reactor scram on March 9, 1988.

The scram occurred at 85 percent power when a technician's error resulted in both recirculation pumps tripping followed by an isolation of the steam supply to the feedwater heaters. With cooler feedwater now being provided into the reactor and under natural circulation conditions, power began oscillating. The reactor tripped when a power spike reached the 118 percent set point on the High Average Power Range Monitor (APRM). All systems functioned as designed and there were no equipment failures. The unit is currently in hot standby.

While the oscillation was a previously analyzed conditicn, and was not unexpected, it has never been seen on a domestic reactor prior to this event.

No fuel damage occurred because of the transient, according to water chemistry samples taken to date.

In order to fully understand the event, obtain all the facts, and to gauge its significance, including operator response and adequacy of existing plant procedures, the AIT was dispatched.

The team includes two NRR representatives, a Region III (Chicago) specialist, and a Regicn III Project Section Chief.

Region III also will issue a Confirmatory Action Letter to the licensee establishing that the unit may not restart until authorized by the Regional Administrator.

The State of Illinois will be notified.

This information is current as of 11 a.m. (CST), March 17, 1988.

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