PNO-III-88-011, on 880213,reactor Tripped from 100% Power Due to Main Turbine Trip.Safety Injection Sys Actuated Due to Low Steamline Pressure Signal.Relief Valve on Seal Leakoff Replaced W/Spare & Other Two Relief Valves Repaired

PNO-III-88-011:on 880213,reactor Tripped from 100% Power Due to Main Turbine Trip.Safety Injection Sys Actuated Due to Low Steamline Pressure Signal.Relief Valve on Seal Leakoff Replaced W/Spare & Other Two Relief Valves Repaired

ML20149J268
Person / Time
Site:	Callaway
Issue date:	02/16/1988
From:	Forney W, Hinds J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-88-011, PNO-III-88-11, NUDOCS 8802220334
Download: ML20149J268 (1)

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-88-11 Date February 16,198 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: Union Electric Licensee Emergency Classification:

Callaway X Notification of an Unusual Even Steedman, Missouri Alert Site Area Emergency Docket No. 50-483 General Emergency Not Applicable

Subject:

REACTOR TRIP AND SUBSEQUENT ECCS ACTUATION At 3:55 a.m. (CST) on February 13, 1988, the reactor tripped from 100 percent power as a result of a main turbine trip. All safety systems performed as expected. At the time of the trip, the licensee was performing surveillance testing on the turbine control system.

A temporary connection (jumper) came loose, grounded to the cabinet and caused the turbine trip.

At 5:22 a.m. the safety injection system (an Emergency Core Cooling System) actuated because of a low steamline pressure signal. The low pressure signal apparently resulted from a faster than normal cooldown, although no excessive cooldown rates occurred. The licensee reported difficulty in transferring plant steam needs to an auxiliary boiler, which necessitated drawing steam from the secondary system.

A relief valve on a seal leakoff return line did not reseat properly after the safety injection signal isolated the normal return path. The valve was replaced with a spare, and two other relief valves -- one in the residual heat removal system and one in the letdown syst:m -- were also repaired.

The licensee classified this incident as an Unusual Event under its emergency plan. The Unusual Event was declared at 5:32 a.m. and terminated at 6:45 a.m.

The plant is expected to return to service on February 16, 1988. The resident inspector has been monitoring the licensee's activities.

The State of Missouri will be notified.

Region III was notified of this event by the Headquarters Operations Center at about 5:30 a.m. on February 13, 1988. This information is current as of 10 a.m., February 16, 1988.

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g22g34 890216 CONTACT:U. Hinds

. Forney PNO-III-80011 PDR FTS 388-5575 FTS 388-5590 DISTRIBUTION:

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