PNO-III-86-063, on 860702,unidentified Leakage from RCS Discovered.Caused by Leak in Resistance Temp Detector Manifold for Reactor Cooling Loop D.Reactor Cooled to Cold Shutdown.Detector Being Repaired

PNO-III-86-063:on 860702,unidentified Leakage from RCS Discovered.Caused by Leak in Resistance Temp Detector Manifold for Reactor Cooling Loop D.Reactor Cooled to Cold Shutdown.Detector Being Repaired

ML20202D541
Person / Time
Site:	Byron
Issue date:	07/07/1986
From:	Forney W, Warnick R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-86-063, PNO-III-86-63, NUDOCS 8607140156
Download: ML20202D541 (1)

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-86-63 Date July 7, 1986 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verifi-cation or evaluation, and is basically all that is known by the Region III staff on this date.

Facility: Commonwealth Edison Company Licensee Emergency Classification:

Byron Unit 1 X Notification of an Unusual Event Byron, IL 61010 Alert Site Area Emergency Docket No. 50-454 General Emergency Not Applicable -

Subject:

REACTOR SHUTDOWN TO REPAIR PRIMARY SYSTEM LEAK At 7:50 p.m. (CDT) on July 2, 1986, the licensee began to shut the unit down as a result of unidentified leakage from the reactor cooling system. (The leakage was measured to be 1.007 gallons per minute; the Technical Specification limit, r: quiring shutdown, is 1 gallon per minute.) The licensee declared an Unusual Ev:nt under its emergency plan. The licensee cooled the reactor to Cold Shutdown conditions and terminated the Unusual Event at 3:00 a.m. (CDT), July 4,1986.

Th2 source of the leakage was determined to be the resistance temperature detector manifold for the "D" reactor cooling loop. The licensee estimates that repa;n will take 14 days, and will perform other maintenance activities during the outage.

The resident inspectors will monitor the licensee's activities.

The State of Illinois will be informed.

R;gion III (Chicago) was notified of this shutdown at 10:20 p.m. (CDT) on July 2, 1986, by the Headquarters Duty Officer. Details on the length of the outage were obtained at 9:00 a.m. (CDT), on July 7, 1986. This information is current as of that time.

(D. RFtd A CONTACT: W. forney R. Warnick FTS 388-5590 FTS 388-5575 DISTRIBUTION:

H. St. ED0 NRR E/W Willste Mail: ADM:DMB Chairman Palladino PA IE NMSS DOT:Trans only Conin. Zech ELD OIA RES Comm. Bernthal AE00 Comm. Roberts Comm. Asselstine SPd//p Regional Offices ACRS SECY INP0 J7 9 NSAC 27 2/

CA RIII Resident Office PDR Licensee: .213 8 (Corp. Office - Reactor Lic. Only)

Region III Ih O I 8607140156 860707 Rev. November 1985 l

Date

-I 86-063 PDR J