PNO-II-85-076, on 850808,reactor Tripped from 99% Power. Caused by Two Blown Fuses.Unit Proceeding to Cold Shutdown & Will Be Out of Svc for 10 Days While Cause Investigated & Reactor Coolant Pumps Inspected

PNO-II-85-076:on 850808,reactor Tripped from 99% Power. Caused by Two Blown Fuses.Unit Proceeding to Cold Shutdown & Will Be Out of Svc for 10 Days While Cause Investigated & Reactor Coolant Pumps Inspected

ML20133N506
Person / Time
Site:	Saint Lucie
Issue date:	08/08/1985
From:	Brownlee V, Elrod S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
References
PNO-II-85-076, PNO-II-85-76, NUDOCS 8508130506
Download: ML20133N506 (2)

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August 8, 1985 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-II-85-76 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verifi-

' cation or evaluation, and is basically all that is known by the Region II staff on this date.

FACILITY: Florida Power & Light Company Licensee Emergency Classification:

St. Lucie Unit 2 X Notification of Unusual Event Docket No. 50-389 Alert Fort Pierce, Florida Site Area Emergency General Emergency Not Applicable

SUBJECT:

POWER LOSS TO ENGINEERED SAFEGUARDS INSTRUMENTATION TRAIN St. Lucie Unit 2 tripped off line from 99 percent power at 2:06 a.m. (EDT) today after two fuses blew, interrupting power to an instrumentation cabinet and causing actuation of one of thi two trains of engineered safeguards features (ESF).

As part of that ESF actuation, containment isolation interrupted the flow of component cooling water through a containment penetration line which serves all four reactor coolant However, pumps. This common isolation valve was later reopened from the control room.

individual isolation valves inside containment controlling component cooling water flow to two of the reactor coolant pumps could not be reopened because these valves are powered by a s:parate power supply which is cut off with ESF actuation.

Aftcr the containment isolation occurred, control room operators manually tripped all four reactor coolant pumps, later restarting the two for which component cooling water could be restored. About an hour after the transient began, the second ESF train was actuated as the result of low pressurizer pressure, but was terminated within approximately five minutes when pressure was restored above the triggering setpoint.

- The plant used natural circulation to remove decay heat while all reactor coolant pumps were stopped. Auxiliary feedwater operated as required. The unit is now proceeding to cold shutdown. Florida Power & Light (FPL) estimates it will be out of service for 10 days while the cause of the blown fuses is investigated and the reactor coolant pumps are inspected.

In accordance with the St. Lucie emergency plan, FPL declared an unusual event at 3:10 a.m.

and terminated it at 6:31 a.m. The resident inspector was on site at 3 a.m. for routine inspection and followed the event.

St. Lucie Unit 1 is operating at 99 percent power.

Both FPL and Region II have responded to media inquiries.

Th3 State of Florida has been informed.

FPL notified the NRC headquarters incident response center of this incident by telephone at 3:25 a.m. today. This infonnation is current as of noon today.

Contact:

S. A. Elrod, 242-5536 V. L. Brownlee, 242-5583 e50st30y6 e5000s M-11-05-076 PDR I E 3 99 oll )

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