PNO-III-85-102, on 851214,during Outage,Both Trains of RHR Sys Lost When Water in Reactor Vessel Drained Below Level of Suction Line.Caused by Erroneous Control Room Indication of RCS Configuration Used for Outage

PNO-III-85-102:on 851214,during Outage,Both Trains of RHR Sys Lost When Water in Reactor Vessel Drained Below Level of Suction Line.Caused by Erroneous Control Room Indication of RCS Configuration Used for Outage

ML20138L055
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	12/16/1985
From:	Chrissotimos N, Hehl C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-85-102, NUDOCS 8512190156
Download: ML20138L055 (1)

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-85-102 Date December 16, 1985 Thistpreliminary notification constitutes EARLY notice of events of POSSIBLE safety cr 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: Commonw'enthQson Company Licensee Emergency Classification:

Zion Unit 2 - Notification of an Unusual Event Zion, IL 60099 XX Alert Site Area Emergency Docket No: 50-304 General Emergency Not Applicable Subj:ct: FAILURE OF RHR SYSTEM DURING SHUTDOWN At 3:25 a.m. on December 14, 1985, the unit lost both trains of the Residual Heat Removal (RHR) System because water in the reactor vessel was allowed to drain below the level of the sucticn line for the system. The unit is shut down for a refueling outage that began September 5, 1985.

The event occurred because control personnel were relying on normal control room indication of th2 reactor vessel water level. The control room indication was erroneous in the reactor coolant system (RCS) configuration in use at this point in the outage.

The licensee reported that the reactor vessel level had dropped about 6 inches before it was rest: red using a charging pump and gravity feeding water from the Refueling Water Storage Tank. One train of-the RHR system was restarted at 4:30 a.m., after the vessel level had been' restored, and the second train was restored at 4:50 a.m. RCS temperature increased only about 15 degrees Farenheit during this event.

Th3 Iicensee declared an Alert under its emergency plan at 3:25 a.m. The Alert was terminated at 4:40 a.m.

The State of Illinois will be notified.

Th] r;sident inspectors will review the circumstances of the event.

-Region III (Chicago) was notified of the event at about 4:17 a.m. December 14, 1985. This

.information is current as of 10 a.m., December 16, 1985.

CONTACT:-

/!r hit--

C.W. Hehl h/k&

N.J. Chrissotimos FTS 388-5552 FTS 388-5716 DISTRIBUTION:

H. St. E00 NRR E/W Willste Mail: ADM:DMB Chairman Palladino PA IE NMSS D0T:Trans only Comm. Zech ELD OIA RES Comm. Bernthal AEOD

-Comm. Roberts Conan. Asselstine SP/,'O[

Regional Offices b 3O ACRS SECY INP0/.*a# NSAC l:0 F $ !

RIII Resident Offict, CA PDR Licensee: 1,* l 5 (Corp. Office - Reactor Lic. Only)

$ 217 p 8512M Region III PNO-III-85-102 PDR Rev. November 1985