PNO-V-88-013, on 880213,plant Experienced Condenser Tube Failure & Shut Down Manually Scramming Plant from 35% Power. on 880214,reactor Bldg Air Supply Fan Started W/O Trip Circuit Being Energized.Cause Under Investigation

PNO-V-88-013:on 880213,plant Experienced Condenser Tube Failure & Shut Down Manually Scramming Plant from 35% Power. on 880214,reactor Bldg Air Supply Fan Started W/O Trip Circuit Being Energized.Cause Under Investigation

ML20149J070
Person / Time
Site:	Columbia
Issue date:	02/16/1988
From:	Bosted C, Johnson P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-88-013, PNO-V-88-13, NUDOCS 8802220259
Download: ML20149J070 (2)

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_ PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-88,-13 Date 02/16/88 This preliminary r.oti>ication constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information presented is as initially received ,

eithout verification ar evaluation and is basically all that is knorn by Region V staff on this date.

FACILITY: Washington Public Power Supply System Emergency Classification WNP-2 Notification of Unusual Event DOCKET NO. 597 50 3 Alert i Richland, Washington Site Area Emergency  ;

General Emergency

• XX Not Applicable

SUBJECT:

FAILURE OF SECONDARY CONTAINMENT On Saturday, February 13, 1988, WNP-2 experienced a condenser tube failure and was shutdown by manually scramming the plant from 35% power. The plant had been operating at 100% at the time of the condenser tube failure.

Operators reduced power by shifting the reactor recirculation (RRC) pumps to slow speed just prior to tripping the reactor. The plant was taken to cold shutdown (Mode 4) and while troubleshooting the condenser tube leak, technicians were inspecting 480 VAC breakers per NRC Bulletin 88-01.

l On Sunday, February 14, at approximately 9:40 pm, while restoring electrical breakers for the reactor building supply and exhaust air fans, the reactor building air supply fan R0A FN 1A was somehow started without the trip circuit being energized. (All protective features and fan status indicating lights are powered from the breaker trip power supply.) The fan apparently started when the operator took the fan breaker control switch from the pull-to-lock position. The cause of the fan starting is under investigation.

The operator did not have indication that the breaker was closed and only then the control room supervisor (CRS) noted that the secondary containment pressure recorder had indicated approximately 6.5 in.(H2O) and subsequently

reduced to 1.5 in, were steps taken to control the reactor building .ir pressure. Af ter attempts to adjust the pressure were unsuccessful, an i

equipment operator was sent to check fan RCA FN 1A which was determined to be running. The fan breaker was manually tripped.

At approximately 11:30 pm, during the reliet ing crew's initial tour of the plant, an equipment operator noticed that soveral nuts and bolts were lying on the refueling floor (this is the uppermoit enclosed level in the reactor

' building). Subsequent investigation revealed that the secondary containment  !

roof was damaged. This roof covers the eq'sipment housed on or above the reactor refueling floor including the spert fuel pool.

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i Plant staff nembers believe that during the reactor building pressurization, the roof panels lifted, bowed outward, and the panels parted at the bolted seams. The damage assessment performed by plant staff on the morning of February 15 indicates that most of the roof panels have moved, some as much as 9-12 inches and several panels have not fully reseated. Two panels are currently displaced approximately eight inches from the normal height. These panels were designed to be blow-out devices, and the shear bolts assembling the panels are designed to break at low forces. The licensee has perfonned a preliminary inspection of the spent fuel pool, which is located under one of the displaced panels, and has determined that some debris has fallen into the spent fuel pool. .The licensee has had no indication that any of the spent fuel stored in the pool is damaged. A cover has been erected over the spent fuel pool to prevent further debris from falling into the pool during the roof repair. Additional inspections of other plant equipment (including primary containment penetrations, plant instrumentation, and other secondary containment vertical walls) for potential effects of over pressurization are ongoing. Plant management estimates that the plant will be shutdown approximately seven days to repair the roof. Technical specifications do not allow plant operation above Mode 4 without secondary containment.

The condenser tube leak was identified to have been caused by a weld failure of a baffle plate on the feedwater heater #1 drain return inlet to the condenser. The baffle plate was rewelded in place, and the leaking tubes were plugged. Three leaking tubes were identified. '

This inform iscurrentasof8:30am(PST) February 16, 1988.

CONTACT: P. Jo)fnson C. Bosted FTS 453-3745 (509) 377-2627 DISTRIBUTION H St. MNBB E/W Willste Mail:

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