PNO-III-85-092A, on 851023,unit Shut Down Due to High Neutron Flux During Startup.Insp Team Concluded That Reactor Sys Equipment Functioned Acceptably.Electronic Circuit Cards Replaced

PNO-III-85-092A:on 851023,unit Shut Down Due to High Neutron Flux During Startup.Insp Team Concluded That Reactor Sys Equipment Functioned Acceptably.Electronic Circuit Cards Replaced

ML20138H956
Person / Time
Site:	La Crosse File:Dairyland Power Cooperative icon.png
Issue date:	10/24/1985
From:	Boyd D, Chrissotimos N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
CAL-RIII-85-14, PNO-III-85-092A, PNO-III-85-92A, NUDOCS 8510290192
Download: ML20138H956 (2)

m PRELIMUlARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRINCE--PNO-III-85-92A Date October 24, 1985 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or 'h/Il public interest significance. The information is as initially received without veri- V fication or evaluation, and is basically all that is known by the staff on this date.

Facility: Dairyland Power Cooperative Licensee Emergency Classification:

Lacrosse Boiling Water Reactor Notification of an Unusual Event Genoa, WI 54632 XX Alert Site Area Emergency Docket No: 50-409 General Emergency $

Not Applicable

Subject:

SHUTDOWN BECAUSE OF HIGHER TiiAN EXPECTED NEUTRON FLUX DURING STARTUP (UPDATE)

A special Region III (Chicago) inspection team has concluded that all Reactor Protection System equipment was functioning acceptably and there was no failure of the reactor to scram (shut down automatically) in the event of October 23, 1985.

Two control room alarms on high neutron flux in the reactor were received in the event--the second alarm was triggered at flux level where an automatic trip of the reactor protection system would be expected.

The licensee performed thorough and repeated testing of the alarm and Reactor Protection System circuits, and these tests were monitored by the Region III team, which included the Senior Resident Inspector. The testing showed that a small difference in the pick up point of the relays for the alarm circuit and RPS circuit existed. The power range monitor signal briefly reached the alarm point, but was not of sufficient strength or duration to trigger the relay in the Reactor Protection System to result in an automatic reactor trip.

The testing also demonstrated that had a sustained increasing flux signal been present during the event, the power range monitor would have generated a reactor scram signal within the required flux range. The scram function of the reactor was also tested and shown to function as designed. The other three power range monitors were also tested and found to function properly.

To preclude a recurrence of this event, the licensee has replaced electronic circuit cards in both the high flux alarm relay and the high flux Reactor Protection System relay (for Channel 6) so that they will both pick up at essentially the same time under the same conditions. The removed circuitry will be analyzed by the licensee to determine if any of the individual components have become degraded in any manner.

Region III issued a Confirmatory Action Letter to the licensee on October 23,1985,(CAL RIII-85-14) confirming the licensee's agreement not to resume operations until the incident was thoroughly reviewed and startup was approved by the NRC Regional Administrator or his designee. Following the tests and evaluations, Region III has authorized the plant to resume oparation and preparations for startup are underway.

8510290192 851024 b PDR .T&E 4 i PNO-III-85-072 PDR P sh

PRELIMIllARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-85-92A Date October 24, 1985 The State of Wisconsin will be informed.

{ Tha Region III special inspection team completed its on-site review about 2:30 a.m.,

! Atober 24, 1985. The startup activities will be monitored by the Senior Resident Inspector. This information is current as of 9:30 a.m., October 24, 1985.

f/ $ #

CONTACT: D. Boyd N. Chrissotimos 1

FTS 388-5546 FTS 388-5716 i

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