PNO-III-89-033, on 890308,high Radiation Alarm Received When Vent & Drain Valves of Coolant Vol Control Sys 1A Mixed Bed Demineralizer Opened.Caused by Use of Erroneous Stack Flow Rate.New Calculations Determined Release Rate within Limits

PNO-III-89-033:on 890308,high Radiation Alarm Received When Vent & Drain Valves of Coolant Vol Control Sys 1A Mixed Bed Demineralizer Opened.Caused by Use of Erroneous Stack Flow Rate.New Calculations Determined Release Rate within Limits

ML20246N261
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	03/08/1989
From:	Greenman E, Hinds J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-89-033, PNO-III-89-33, NUDOCS 8905190391
Download: ML20246N261 (1)

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P8ELIMftlARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-III-89-33 Date Mah 8,1989 ACD-This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially receiv:d without , verification or evaluation, and is basically all that is known by the Region III staff on this date. t Facility: Commonwealth Edison Co. Licensee Emergency Zion Unit 1 Classification:

Zion, IL 60099 X Unusual Event (/t i Alert I Docket No. 50-295 Site Area Emergency General Emergency Not Applicable

Subject:

UNPLANNED GASE0US RELEASE 4

At 9:45 a.m. (CDT), May 8,1989, while operating at 99 percent power, operators opened the vent and drain valves of the coolant volume control system 1A mixed bed demineralized to begin preparations to change resins. Shortly after the valves were opened, operators l received a high radiation alarm on the auxiliary building vent stack radiation monitor. At the same time, operators noticed that the volume control tank level was decreasing between 20 and 30 gallons per minute.

The licensee suspected that either the inlet or the outlet valves to the 1A resin bed was leaking and diverting letdown water through the demineralized vent valves to the auxiliary building. At 9:55 a.m., the demineralized was isolated and the release was terminated.

Initially, the licencee calculated the release to be in excess of technical specifications and declared an unusual event, in accordance with its emergency classification procedure.

The States of Illinois and Wisconsin were notified.

A subsequent review revealed that an erroneous stack flow rate had been used resulting in erroneously high readings. New calculations determined that the release rate was well within defined limits.

Region III (Chicago) is monitoring the licensee's investigation of this incident.

The State of Illinois will be notified.

Region III was first notified of this event at 12 noon (CDT), May 8, 1989. This information )

is current as of 3:30 p.m. (CDT), May 8, 1989.

. w'_. % (h f CONTAC . M. Hinds E. G. Greenman FTS 388-5575 FTS 388-5518 DISTRIBUTION:

WHITE FLINT NORTH 1 MNBB REGIONS FAX T0:

Chairman Zech CA AEOD RI INP0 4:;35 Comm. Roberts OGC ARM RII NSAC yla7 ,_.

Comm. Carr 01 OIA RIV Licensee 4:3o Comm. Rogers EDO RV NRC Ops Ctr C.J)9 Comm. Curtiss NRR NL MAIL T0: PDR(8/634-3343Ty;3g SECY NMSS RTS DCS (Orig.)

GPA/SLITP/PA ACRS DOT (Trans. Only) ,

Rev. 03/01/89 (

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8905190391 890308 ./

PDR I 8cE PNO-III-89-033 PNU / b, J

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