PNO-III-88-081, on 880916,reactor Operators Observed Decrease in Flow Through Offgas Sys,Coupled W/Drop in Generator Electrical Output & Decrease in Main Condenser Vacuum. Plant Shut Down for Investigation Into Offgas Problem

PNO-III-88-081:on 880916,reactor Operators Observed Decrease in Flow Through Offgas Sys,Coupled W/Drop in Generator Electrical Output & Decrease in Main Condenser Vacuum. Plant Shut Down for Investigation Into Offgas Problem

ML20154L903
Person / Time
Site:	Perry
Issue date:	09/19/1988
From:	Cooper R, Knop R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-88-081, PNO-III-88-81, NUDOCS 8809260339
Download: ML20154L903 (2)

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-88-81 Date September 19, 1988 bcb x .

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: Cleveland Electric Illuminating Licensee Emergency Classification:

Company X Notification of an Unusual Event [

Perry Alert Perry, OH 44081 Site Area Emergency General Emergency <

Docket No. 50-440 Not Applicable

Subject:

SHUTOOWN TO INVESTIGATE OFFGAS SYSTEM PROBLEM On September 16, 1988, reactor operators observed a decrease in the flow throu the offgas system, coupled with a drop in generator electrical output and a decrease in the main condenser vacuum. The plant had been operating at 100 percent power. (Theoffgassystem draws noncondensible gases from the condenser. The gases pass through a hydrogen recombiner, particulate filters, and a series of charcoal adsorber tanks before being released to the atmosphere.)

Operators began to reduce power and placed a second steam jet air ejector inservice. The nitrogen flow was also increased into the first charcoal tanks of both four-tank charcoal

, adsorber systems. A nitrogen purge of the tanks has been maintained since September 4, 1988, when the charcoal began to burn. (

Reference:

PNO-III-88-78)

" Subsequently, there were two "booms" heard by licensee personnel with a simultaneous spike in the flow rate through the offgas system. Elevated carbon monoxide levels were also detected in an offgas sample. The licensee has not determined if the spikes and sounds were '

caused by a hydrogen burn or by a water hamer in a loop seal.

There is no evidence of any further burning in the charcoal adsorber tanks. Throughout the event there was no increase in temperature levels in the two tanks affected earlier.

I The licensee declared an unusual event under its emergency plan and a prior agreement with

. Region III at 10:02 p.m. and began to shut the plant down to investigate the offgas problem.

lTheunusualeventwasterminatedat7:30a.m.onSeptember 18, 1988.

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DISTRIBUTION

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! 0809260339 890919 Rev. June 1988 N-I - ..88-081 PNV,

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PRELIMINARY' NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-ffl-88-81 Date September 19, 1988 The resident inspector arrived at the plant at 10:45 p.m. on September 17, 1988, to monitor the licensee's activities. Region III will dispatch additional inspectors to the site to i review the licensee's investigation and assessment of the offgas system problem. )

The State of Ohio has been notified of this event.

The licensee notified the Headquarters Operation Center of this event at 10:19 p.m. (EDT) on September 16, 1988. This information is current as of 10 a.m., September 19, 1988.

CONTACT:

'$l9ffV R. W. Cooper bl R. C. Knop

• ff FTS 388-5578 FTS 388-5547

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