PNO-I-98-021, on 980609,automatic Reactor Scram Occurred. Except for Single Control Rod Position Indication Problem, Initial Plant Response to Scram Expected.Licensee Initiated Investigation to Understand Causes of Event Complications
| ML20248L807 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 06/09/1998 |
| From: | Cowgill C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| References | |
| PNO-I-98-021, PNO-I-98-21, NUDOCS 9806110370 | |
| Download: ML20248L807 (2) | |
,
, June 9,
1998 PRELIMINARY NOTIFICATION OF BVENT OR umunuaL OCCUnu mCE PNO-I-98-021 This preliminary notification constitutes EARLY notice of events of POSSIPLE sofoty or public. interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by Region I staff in King of Prussia, Pennsylvania on this date.
Facility Licensee Eneroency Classification Vermont Yankee Nuclear Power Corp.
Notification of Unusual Event Vormont Yankee 1 Alert Vornon, Vermont Site Area Emergency
)
Dockets: 50-271 General Emergency l
X Not Applicable
Subject:
REACTOR SCRAM WITH COMPLICATIONS - MEDIA INTEREST
.At 1:32 a.m.
on June 9, 1998, an automatic reactor scram occurred from about 68 percent power.
The scram was a result of a main turbine trip that occurred due to a reactor vessel high water level condition resulting from an apparent failure of the "A"
feedwater regulating valve (FRV).
Except for a single control rod ponition indication problem, the initial plant response to the scram was as expected.
At the time of the event, operators had been reducing power in preparation for taking the "B" reactor recirculating water pump motor-generator (M-G) set off-line due to a high bearing temperature condition.
With the power reduction in progress, the "A" FRV did not respond properly in either auto or manual control and caused the high rouctor vessel water level condition.
Subosquent to the scram a number of problems occurred that are currently boing evaluated, including: (1) a trip of the "C" main feedwater pump (NFP) ; (2) the auto-start of two MFPs "A"
and "B" when the "C"
MFP tripped; (3) a Group 1 isolation (MSIV closure) during electrical bus rccovery; and (4) the tripping of the "B" Recirculation pump motor gancrator.
1 As of 9:00 a.m. on June 9, 1998, the reactor plant is stable in hot chutdown conditions with natural circulation este.blished.
Reactor vessel water leve3 and pressure are being controlled manually with the Reactor Icolation Cooling (RCIC) system.
Operators are preparing to restore the main condenser to service as the heat sink so that conditions can be achioved to re-establish forced circulation by restarting the "An reactor i
rceirculating water pump.
All ECCS equipment and on-site emergency power
. systems are available and all vital and non-vital buses have been rectored to off-site power supplies.
The licensee has' initiated an-investigation to understand the causes of the cvent complications, as.well as troubleshooting the balance of plant equipment that failed to respond as. expected.
The Senior Resident. Inspector was dispatched to the site when the NRC was notified of the event approximately 4:00 a.m.
The regional office is making plans to dispatch a special inspection team to review the circumstances associated with the event.
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9906110370 99060, PDR IEE PNO-I-99-021 PDR t
a
i Tho licensee issued a press releatse about the reactor shutdown.
Th5 State of Vermont has.been notified.
Contcct:
C.
Cowgill (610)337-5233 1
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