PNO-IV-98-026, on 980617,northeast Stairwell of Reactor Bldg Was Flooded Due to Fire Header Line Valve Rupture.Pumping Activities Were Effective in Removing Water from Affected Areas.State of Wa Has Been Informed
| ML17292B407 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 06/18/1998 |
| From: | Boynton S, Wong H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-IV-98-026, PNO-IV-98-26, NUDOCS 9806190286 | |
| Download: ML17292B407 (4) | |
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CATEGORY 1 ~
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9806190286 DOC.DATE: 98/06/18 NOTARIZED: NO FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe AUTH.NAME AUTHOR AFFILIATION BOYNTON,S.
Region 4 (Post 820201)
WONG,H.
Region 4 (Post 820201)
RECIP.NAME RECIPIENT AFFILIATION DOCKET 05000397
SUBJECT:
PNO-IV-98-026:on 980617,northeast stairwell of reactor bldg was flooded due to fire header line valve rupture. Pumping activities were effective in removing water from affected areas. State of WA has been informed.
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LTTR 39 ENCL 15
June 18, 1998 PRELIMINARY OTIFICATIONOF EVENT OR UNUSUALOCCURRENCE PNO-IV-98-026 This preliminary 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 Region IV staff in Arlington, Texas on this date.
~Faclli Washington Public Power Supply System Washington Nuclear 2 Richland, Washington Dockets: 50-397 Licensee Emer enc Classification X Notification of Unusual Event Alert Site Area Emergency General Emergency Not Applicable
Subject:
INTERNALFLOODING CAUSED BY FIRE HEADER LINE VALVERUPTURE At approximately 1:45 p.m. PDT on June 17, 1998, multiple fire alarms were received in the WNP-2 control room coincident with all four fire pumps automatically starting and several loud water hammer noises being heard from the control room. The water hammer caused a valve to rupture in the fire protection system main header in the northeast staiiwell of the reactor building. The water in the stairwell quickly rose to approximately 19 feet in depth.
Water from the stairwell entered residual heat removal Pump Room C through an open watertight door and eventually submerged the pump motor. A ground developed on the Division II, 125-volt DC bus, which supplies control power to residual heat removal Pump C, which subsequently cleared. A valve located in a line connecting the sumps of the residual heat removal Pump C and low pressure core spray pump rooms failed to close, allowing water to enter the low pressure core spray pump room. Water eventually crested approximately 1 foot below the base of the low pressure core spray pump motor. The licensee secured the fire protection system and electrical supplies to the affected rooms.
At 2:14 p.m. PDT,the licensee declared a notification of unusual event due to loss of plant fire protection. The licensee staffed the technical support center and operations support center to provide support to the control room and to control work activities within the plant. All work, except for event recovery work, was halted.
At the time of the event, the unit was shut down in Mode 4 with the reactor coolant system at 133 degrees F following a forced outage that occurred during restart from an extended refueling outage. The licensee is maintaining residual heat removal system Pump A in decay heat removal mode. Pump B, which is currently aligned to provide suppression pool cooling, is also available for shutdown cooling. Condensate pumps are available to cool the core ifthe residual heat removal pumps are lost. Primary containment has been maintained and the offsite power supply is stable.
980bf90286 980618 PDR XSE Pl40- XV-98-02b PDR
PNO-IV-98-026 Following notification, the NRC entered the monitoring phase of the normal mode of operation with monitoring from the Region IV Incident Response Center and support provided
'rom NRC Headquarters.
The Senior Resident Inspector responded to the event. A Senior Project Engineer from the Walnut Creek Field Office was onsite at the time of the event and promptly responded to the control room. An additional inspector was dispatched to the site to help provide 24-hour coverage of licensee response and recovery operations.
NRC Region IV briefed FEMA Region X and the state of Washington on the event.
After sampling for contamination, the licensee began pumping water from the flooded areas to a storm drain outside of the reactor building. A short time after pumping to the storm drain began, a subsequent sample detected low levels of radioactivity in the water and the pumping to the storm drains was secured. The pumps used to remove the water from the flooded areas were then aligned to the large sump under the condenser.
This sump is designed to receive radioactively contaminated water. Pumping activities were effective in removing water from the affected areas.
The licensee verified that, although it tost the fire protection suppression system during the event, the fire detection capability was not affected. The fire protection system has not yet been returned to service. To provide fire protection system supplementation, the Hanford Fire Department responded to the site with two fire engine pumper trucks, two 5000 gallon fire tender trucks, and two complete crews. While there were no reports of injuries, two ambulances accompanied the fire pumpers and tenders.
At the time of the event, reporters from the Seattle Times, the Seattle Post Intelligencer, and the Tri-City Herald were onsite. They were briefed by the licensee while the event was in progress. There has been media interest in this event. The licensee and the NRC have both issued press releases.
The state of Washington has been informed.
Region IV received notification of this occurrence by telephone from the Senior Project Engineer onsite at 2:30 PDT. Region IV has informed the EDO, NRR, and PA.
This information has been discussed with the licensee and is current as of 8 a.m. PDT.
Contact:
Scott Boynton (509)377-2627 Howard Wong (925)975-0296
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