PNO-I-98-019, on 980603,operators Found One of Three Standby Liquid Injection Pumps Running & Injecting Into Reactor Vessel.No Alarms Identified on Redundant Reactivity Control Sys Which Provides Automatic SLC Initiation Feature

PNO-I-98-019:on 980603,operators Found One of Three Standby Liquid Injection Pumps Running & Injecting Into Reactor Vessel.No Alarms Identified on Redundant Reactivity Control Sys Which Provides Automatic SLC Initiation Feature

ML20248L800
Person / Time
Site:	Limerick
Issue date:	06/04/1998
From:	Anderson C, Arthur Burritt NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-98-019, PNO-I-98-19, NUDOCS 9806110365
Download: ML20248L800 (2)

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RggLI$tINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-I-98-019 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 Region I staff in King of Prussia, Pennsylvania on this date.

Facility Licensee Emeroency Classification Pcco Energy Company. Notification of Unusual Event Linarick 2 Alert Phi.ladelphia, Pennsylvania Site Ares Emergency Dockets: 50-353 General Emergency X Not Applicable

Subject:

INADVERTENT STANDBY LIQUID INJECTION - SHUTDOWN EXTENDED GREATER THAN 72-HOUL5 On June 3, at 9:14 a.m.,

with the Limerick Unit 2 in cold shutdown at 116 dsgrees Fahrenheit, operators noticed a reactor water cleanup (RWCU) isolation. At 9:20 a.m., while investigating the reason for the RWCU icolation and shortly after a standby liquid (SLC) tank low level alarm, oporators found one of the three standby liquid injection pumps running cnd injecting into the reactor vessel. Operators secured the SLC pump and isolated the injection line to the reactor vessel. No alarms were identified on the redundant reactivity control system (RRCS) which provides an automatic SLC initiation feature at Limerick. Operators confirmed that no work activities were being performed on or in the vicinity of equipment associated witn the SLC system and no other enemalous conditions existed. The licensee estimated that no more than 350 gallons of sodium pentaborate were injected over a six minute period.

The licensee is in the process of trouble shooting the RRCS system and standby liquid system control circuits; however, no cause for the initiation has been identified. The reactor water cleanup isolation has boon confirmed to be as a result of the SLC initiation as required.

The reactor water cleanup system has been returned to service and a feed and bleed of the reactor vessel is in progress. The horated water is boing processed through the radwaste system and, after being verified within environmental limits, being discharged to the Schuykill River.

Reactor conductivity levels are lowering and the licensee anticipates about 3 days will be required to restore reactor chemistry to the normal vc3ues. The impact of the sodium pentaborate on the reactor vessel and internals carbon steel components, and the fuel, is also being evaluated.

The resident inspector is following PECO Energy's continuing assessments cnd corrective actions. A regional inspector has also been dispatched to provida assistance. In addition, a six-person NRC engineering team was alrosdy onsite conducting a separate inspection and will provide technical support as necessary and evaluate the licensee's root cause offorts.

This Commonwealth of Pennsylvania has been notified. The Region I Public Affairo Office is prepared to answer inquiries.

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PNO-I-90-019 PDR

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s Region I received initial notification of this occurrence by a telephone call from the Senior Resident Inspector at approximately 11:00 a.m. on

'Juns 3, 1998. The information presented herein is current as of 11:30

- e.za. oh June 4, 1998.

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Conthcts ANDERSON, CLIFFORD BURRITT, ART (610)337-5227 (610)327-1344 1

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