PNO-III-92-043, on 920827,while Unit 2 Reducing Power to 800 Mw,Turbine Tripped Due to Thrust Bearing Wear Detector Signal.Several Equipment Problems Occurred Following Scram. Operators Successfully Established Steam Flow to Condenser

PNO-III-92-043:on 920827,while Unit 2 Reducing Power to 800 Mw,Turbine Tripped Due to Thrust Bearing Wear Detector Signal.Several Equipment Problems Occurred Following Scram. Operators Successfully Established Steam Flow to Condenser

ML20203G281
Person / Time
Site:	LaSalle
Issue date:	08/27/1992
From:	Beverly Clayton, Knop R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-92-043, PNO-III-92-43, NUDOCS 9712180095
Download: ML20203G281 (2)

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,, av2v92 14:09 7m 790 5693 , Mt

. c l)hl UM w* i~ ;W p:aff J  ;

i Date: August 27, 1992 l

PRELIMINARY NOTIFICATION OF EVENT OR UNU$UAL OCCURRENCE PN39243 1

(

This preliminary notification constitutes EARLY notice of events of P0881BLE i

safety er public interest significance. The information is as initially  !

received without verification or evaluation, and is basically all that is known  !

3 by the Region !!! staff on this date.

Facility: Lle=amma roaraaaev clamairication ,

LaSalle Unit t Genera' Emergency  !

Commonwealth Edison Co. Site Area Emergency l Seneca, Illinois Alert

• Unusual Event ,

Docket No. 50-374 ZN/A i

Subject:

AIT TO REVIEW EQUIPMENT PR08tLMS FOLLOWING REACTOR SCRAM ACd on August 27, 1992, v' '

At 3:10 a.m.

megawatts (CDT)ical), the turbine tripped due to a thrust bearing wearwhile Unit I w (electr >

j detector s gnal, following the turbine trip, the reactor scrammed i

automatically.

Several equipment problems occurred following the scram I

1.- Water level in the reactor increased, and reactor operators were unable to i trip the two reactor feedwater pump turbines from the control room. An operator was sent to the pump area to manually trtiffhe turbines, but was able to trip i

only one of the two turbines after several attempts. The second turbine -

subsequently tripped for an unknown reason. ,

2. The instrumentation and alam systems for the safety relief valves did not l function properly as the safety relief valves were und to control reactor water l pressure. -

3. The Reactor Core Isolation Cooling system initiated prior to its setpoint.  ?

The system was secured. Subsequently, when operators attempted to start it manually, the system failed to start initially, but was started on the second attempt.

4. When reactor operators attempted to open the Main Steam Isolation Valves to ,

direct steam to the main condenser, a Group 1 isolation (signal to isolate the '

reactor cooling system steam) occurred on a signal of high main steam line flow. '

Operators successfully established the steam flow to the condenser, and the unit t is being placed in cold shutdown.

[

.. Region !!! is /

dispatching an (Chicago),assistedbytheOfficeofNuclearReactorRegulationblems A nted Inspection Team (AIT) to review the equipment pro 1

which occurred fo owing the reactor scram. The resident inspectors continue to monitor the event.- yap !

The State of Illinois will be notified. The information in this preliminary notification has been reviewed with licensee management.

Region Ill will issue a news announcement on the AIT review of the event, g21 5 920837 ,

PNO-III-92-043 PDR  !

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I' Date Appust 27, 92 PRELININARY NOT!f! CATION OF EVENT OR UNU50AL OCCURRDCE PN392 3 The 11censee nottfled the NRC Operations Center of this event at 5:07 a.m. (EDT) on August 27, 1992. This information is current as of 10 a.m., August 27, 1992.

CON 1AC1:

R. Knop B. Clayton 708/790-5547 708/790-5574

' DISTRIBUTION:

Jf,&Q(WAlLIf.lL1_Qf.f.lfi REG 10Ns MAIL 101 Region ! DCS (Orig)

Comm3 Rogers OSP Region !! 00T (Trans Comm. CurtIss OPA Reglon IV Only)

Comm. Remick OCA Region V Comm. de Planque CD0 Gen. Counsel OCAA FAL 10t NRR Research The Chairman INPO ,

Af00 IRM t! SAC LIC NRC OHaCTR

, Enforcement ACRS 010 010 PDR(8/634-3343)

HQ Public Affa irs '

LSSA A. Byrdsong, NRR Region IV Region V 4

S eumWapp.e

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