PNO-IV-97-026, on 970506,shutdown Greater than 72 H After Manual Scram Occurred.Div II & III EDGs Started Automatically & Provided Power to safety-related Loads. Licensee Plans to Commence Outage to Repair

PNO-IV-97-026:on 970506,shutdown Greater than 72 H After Manual Scram Occurred.Div II & III EDGs Started Automatically & Provided Power to safety-related Loads. Licensee Plans to Commence Outage to Repair

ML20148A022
Person / Time
Site:	River Bend
Issue date:	05/06/1997
From:	Harrell P, Will Smith NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
References
PNO-IV-97-026, PNO-IV-97-26, NUDOCS 9705070189
Download: ML20148A022 (2)

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l 6-May 6,1997 1

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-IV-97-026 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially I received without verification or evaluation, and is basically all that is known by Region IV staff in Arlington, Texas on this date.

Egcility Licensee Emeraency Classification Entergy Operations, Inc. Notification of Unusual E /ent River Bend 1 Alert l St Francisville, Louisiana Site Area Emergency )

Dockets: 50-458 General Emergency X Not Applicable i

Subject:

SHUTDOWN GREATER THAN 72 HOURS AFTER MANUAL SCRAM On May 6,1997, at 9:02 a.m. (CDT), while operating at 99 percent power, the 13.8-kV l nonsafety-related Bus B and the 4.16-kV safety-related Bus B lost power. The power loss  ;

resulted in the loss of two of the three motor-driven reactor feedwater pumps and reactor j recirculating Pump B. An operator immediately manually scrammed the reactor. The reactor shut down and the main turbine trip occurred in accordance with plant design. Reactor Protection System B power was also lost, since it is supplied by nonsafety-related Bus B, and, as a result, various plant systems isolated, as designed, including cooling water to the reactor

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recirculating pumps. The operators secured Reactor Recirculating Pump A, which initiated )

natural circulation. The alternate power supply to power Reactor Protection System B was provided and the isolated valves and other components were returned to their normal status, i

The Division ll and 111 emergency diesel generators started automatically and provided power to their safety-related loads. The operators maintained reactor level and pressure with one l operating reactor feedwater pump and the turbine bypass system until the outboard main steam isolation valves were closed to conserve heat and reduce cooldown rate. Pressure control was then maintained using the safety relief valves and steam drains. At 11:41 a.m.,

the inboard main steam isolation valves closed on high steam tunnel temperature due to loss of chilled water flow to the coolers.

I All ESF systems responded in accordance with their intended design functions. Offsite power i was not lost or degraded during this event. The plant was in a normal hot shutdown status at approximately 11 ac (CDT). The cause of the loss of power to the 13.8-kV nonsafety-related Bus B is not known at this time.

The licensee plans to commence an outage to repair: (1) a 2 gpm unidentified leak in the l i

drywell; (2) Reactor Recirculation Flow Controi Valve B, which has been stuck at 85 percent  !

open position; and (3) several other minor items. The duration of the outage is unknown at this time because the scope of the flow control valve work will not be known until an inspection of the valve can be performed. The licensee currently estimates that the outage could be as long as 13 days. p

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9705070189 970506 PDR I&E PNO-IV-97-026 PDR Okk l

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4 PNO-IV-97-026

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The state of Louisiana will be informed. Region IV received notification of this occurrence by j telephone from the Senior Resident inspector at 9:20 a.m. (CDT) on May 6,1997. Region >

. IV has informed OEDO, NRR, and PA.

This information has been discussed with the licensee and is current as of 3:32 p.m. on May j 6,1997. )

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Contact:

P. H. Harrell Ward Smith t j (817)860-8250 (504)635-3193 '

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