PNO-I-99-036, on 990718,update to Beaver Valley,Unit 2 Forced Outage Made.Licensee Replaced Suspected Voltage Regulator Control Relays & Satisfactorily Retested EDG 2-2.Resident Inspectors Continue to Monitor Licensee Corrective Action

PNO-I-99-036:on 990718,update to Beaver Valley,Unit 2 Forced Outage Made.Licensee Replaced Suspected Voltage Regulator Control Relays & Satisfactorily Retested EDG 2-2.Resident Inspectors Continue to Monitor Licensee Corrective Action

ML20216D359
Person / Time
Site:	Beaver Valley
Issue date:	07/26/1999
From:	Eselgroth P, David Kern NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-99-036, NUDOCS 9907270247
Download: ML20216D359 (2)

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July 26,1999 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-l-99-036 This preliminary notification constitutes EARLY notice of events of POSSIBLE sifety 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.

Egjllbr. Licensee Emeroency Classification Duqu sne Light CoJ Notification of Unusual Event Be:v:r Valley 2 Alert Shippingport, Pennsylvania Site Area Emergency Dock ts: 50-412 General Emergency X Not Applicable

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Subject:

BEAVER VALLEY UNIT 2 FORCED OUTAGE (UPDATE)

On July 18, operators completed a technical specification required plant shutd:wn from 64 percent reactor power due to an inoperable emergency diesel generator (EDG) which could not be restored within the technical specification allowable outage time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Several problems occurred prior to the shutdown including EDG heat exchanger fouling, a 1:ss of emergency 4KV bus event which led to a temporary Ins of reactor coolint pump seal injection and thermal barrier cooling, and concems r:garding operator use of alarm response procedures. Corrective actions inclJd:d the development of procedures for loss of an emergency 4Kv bus, enc a prioritization scheme for the annunciators and training the operators.

On July 25, the licensee completed its event review and verified short t:rm corrective actions were in place, including the removal of Zebra mussels that had caused the EDG heat exchanger fouling. Detailed EDG and ciectrical bus. testing was conducted. Engineers determined that the most prorble cause of the loss of the 4Kv bus was an intermittent control relsy contact on the 2EG2-2 Voltage Regulator Power Amplifier, (SCR Power Bridge). The loss of the voltage regulation would cause the generator out >ut voltage to change power factor from lagging to leading which would result in a rise in ground current above the expected set point value of pronction relay 50- VF207G. This relay _in tum opened 4KVS-2DF-2F7 tie break r and separated the emergency bus 2DF and the Emergency Diesel 2-2 fror1 the normal bus 4KVS-2D. The licensee replaced the suspected voltage regul: tor control relays and satisfactorily retested the EDG 2-2. The unit was in Mode 5 (Cold Shutdown) as of 10:00 a.m. on July 26, preparing to hnt uo the unit.

A Region i Special inspcction Team was on site July 20-24 to evaluate licensee response to the event. The resident inspectors continue to 9907270247 990726 PDR IhE PND-I-99-036 POR /((0 9

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I.6 monitor licensee corrective action implementation and restart activities.

The contents of this PN have been communicated to the Pennsylvania, Ohio cnd West Virginia state governments.

Cont:ct: P. Eselgroth D.Kem (610)337-5234 (724)643 2000