PNO-III-87-118, on 870906,reactor Shut Down.Caused by Reactor Trip Due to Various Equipment Malfunctions.Two Valves Removed for Insp & Events & Malfunctions Under Evaluation. Confirmatory Action Ltr Re Plant Startup Will Be Issued

PNO-III-87-118:on 870906,reactor Shut Down.Caused by Reactor Trip Due to Various Equipment Malfunctions.Two Valves Removed for Insp & Events & Malfunctions Under Evaluation. Confirmatory Action Ltr Re Plant Startup Will Be Issued

ML20238E042
Person / Time
Site:	Davis Besse
Issue date:	09/08/1987
From:	Defayette R, Guldemond W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
CAL, PNO-III-87-118, NUDOCS 8709140077
Download: ML20238E042 (2)

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PREL_1dNARYNOTIFICATIONOFEVENTORUNUSUALOCCURRENCE--PNO-III-87-118 Date September 8, 1987-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 the Region III staff on this date. .

Facility: Toledo Edison Company Licensee Emergency Classification:

Davis Besse Nuclear Plant Notification of an Unusual Event 5503 N. State Rte #2 Alert Oak Harbor, OH 43449 Site Area Emergency General Emergency Docket No: 50-346 XX Not Applicable

Subject:

REACTOR TRIP DUE TO EQUIPMENT MALFUNCTION; AIT DISPATCHED TO PLANT At about 11:40 a.m. (EDT), September 6, 1987, while the unit was operating at full power, a feedwater flow transmitter failed, causing the integrated control system to increase water

. flow to the steam generators (SG). This resulted in a rapid cooling of the primary coolant,

) increasing reactivity, and causing the reactor to automatically shut down on high

flux at about 11

42 a.m. Several problems occurred during this event including, but not limited to, the following:

the transfer breaker from station to one of two startup transformers did not function, causing a loss of power to a non-vital bus, shutting down two reactor coolant pumps, 1 and causing loss of power to a vital bus. The associated emergency diesel generator j started as required, i a service water pump did not automatically restart after the vital bus was reenergized l (it was restarted manually from the control room).

a main steam safety valve failed to reseat fully.

I

! Subsequent to the event, other problems occurred:

I an operator inadvertently tripped one of the two operating reactor coolant pumps.

_ It was restarted immediately in accordance with plant procedures.

a turbine bypass valve failed open causing a decrease in steam generator level and automatic actuation of the auxiliary feedwater system which functioned properly.

!a pressurizer level decrease due to the presence of unidentified voids in the decay heat system.

The licensee is currently evaluating this event and the various malfunctions. Two steam safety valves (the one which failed to reseat properly and a second one) have been removed for inspection and evaluation.

i blSTRIBUTION:

H. St. ED0 NRR E/W Willste Mail: ADM:DMB E*NW Chairman Zech PA IE NMSS D0T:Trans only Comm. Roberts ELD OIA RES Comm. Bernthal AE00 NRC Ops Ctr Comm. Carr 3.' /O_.

l Comm. Rogers l -ACRS SP 5.'Il Regional Offices dud E SECY d LCA INP0 5.'IS NSAC 5:/6 >C d PDR RIII Resident Office i P = ae: E .' 06 (Corp. Office - Reactor Lic. Only)'

l 8709140077 070908 PDR I&E PNO-II I-B7-118 PDR _g

i PRELIM'JARY NOTIFICATION OF EVENT OR UNVSUAL OCCURRENCE--PNO-f!I-87-118 Date September 8, 1987:

2 Re'gion III management and the Senior Resident Inspector (SRI) monitored the status of the plant throughout the event, and the SRI responded to the-site over the Labor Day Weekend as needed. On Sunday, the day of the event, the licensee verbally agreed not to restart the-reactor without.first contacting the SRI and Region III.

An Augmented Inspection Team, led by a Region III senior manager and supported by NRC Headquarters personnel has-been dispatched to the site (two members of the team are already on site obtaining additional facts). The AIT will have a formal entrance meeting oMWednesday morning, September 9, 1987. .,

A Confirmatory Action Letter -(CAL) is being issued by Region III' confirming that thh' plant will not start up without specific authorization from the Regional Administrator or_ hist.3 designee. -

Th'e State of Ohio will be notified. -

Til .

'This information is current as of 3:30 p.m. (EDT) Se ember 8, 1987, and will be updated by the AIT Team Leader from the site as appropriate.- ~

9/ *

R. DeFayette W.

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CONTACT:

388-5767 388-5574 l

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