05000219/LER-1982-032, Forwards LER 82-032/03L-0.Detailed Event Analysis Encl

Forwards LER 82-032/03L-0.Detailed Event Analysis Encl

ML20054L051
Person / Time
Site:	Oyster Creek
Issue date:	06/25/1982
From:	Fiedler P GENERAL PUBLIC UTILITIES CORP.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20054L052	List: 05000219/LER-1982-032, Forwards LER 82-032/03L-0.Detailed Event Analysis Encl 05000219/LER-1982-032-03, /03L-0:on 820524,during Reactor Shutdown,B Main Steam Line Tunnel Rod Monitors Output Failed Downscale. Caused by Drift of Grid Bias on front-end Amplifier.Drawer Replaced W/Operational Spare
References
NUDOCS 8207070113
Download: ML20054L051 (3)

LER-1982-032, Forwards LER 82-032/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2191982032R00 - NRC Website

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GPU Nuclear g

g7 P.O. Box 388 Forked River, New Jersey 08731 609-693-6000 Writer's Direct Dial Nurnber:

June 25, 1982 Mr. Ronald C. Haynes, Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

Dear Mr. Haynes:

Subject: Oyster Creek Nuclear Generating Station Docke t No. 50-219 Licensee Event Report Reportable Occurrence No. 50-219 /82-3 2 /03L This letter forwards three copies of a Licensee Event Report to report Reportable Occurrence No. 50-219/82-32/03L in compliance with paragraph 6.9.2.b.2 of the Technical Specifications.

Very truly your s, Peter B. Fiedler Vice President & Director Oyster Creek PBF:Ise Enc losu re s cc:

Director (40 copies)

Of fice of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Director (3)

Of fice of Management Inf ormation and Program Control U.S. Nuclear Regulatory Commission Washington, D.C.

20555 NRC Resident Inspector (1)

Oyster Creek Nuclear Generating Station Forked River, NJ 08731 8207070113 820625 gh DR ADOCK 05000 GPU Nuclear is a part of the General Pubhc Utihties System

OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reporcable Occurrence No. 50-219/82-32/03L Report Date June 25, 1982 Occurrence Date May 24,1982 Identification of Occurrence At approximately 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />, the output of the "B" Main Steam Line Tunnel Radiation Monitcr failed in a downscale direction.

Since reliable operability for this monitor was lost (reference Technical Specifications, Section 3.1, Table 3.1.1, Items A7 and B6), this event is considered to be a reportable occurrence as defined in paragraph 6.9.2.b.2 of the Technical Specifications.

Conditions Prior to Occurrence The reactor was undergoing a normal controlled shutdown.

Mode Switch Position:

Run MWt:

462 MWe:

110 Description of Occurrence The "B" Main Steam High Radiation Monitor failed downscale while conducting a normal reactor shutdown.

This monitor provides a High Radiation Alarm and an input to the Reactor Protection Trip System. The reactor shutdown was continued and the action statement and Technical Specification Table 3.1.1 was satisfied.

Diagnostic results indicated that the downscale reading was due to the front end amplifier tube operating in a cut-of f state. The zero control that regulates grid bias on the amplifier tube needed readjustment in order to be restored to an operable status.

Apparent Cause of Occurrence Drif t of the grid voltage control circuit on the front end amplifier was the apparent cause of the monitor to fail downscale.

M 4

Licensee Event Report Page 2 Reportable Occurrence No. 50-219/82-32/03L i

Analysis of Occurrence The Main Steam Line Tunnel Radiation Monitor provides a low level alarm, a high level ala rm, and a high-high level trip signal to the Reactor Protection System. There are four such monitors that provide a one-out-of-two twice logic for a reactor scram on high-high radiation in the main steam line.

Since the redundant monitor and channel were fully operational, the safety significance of this event is minimal.

Corrective Action

The immediate corrective action was to diagnose the problem area, which led to the replacement of the drawer section of the monitoring system. The problem with the f ailed drawer was corrected, and the drawer was returned to service as an operational spare.

Failure Data j

General Electric Co.

Log Radiation Monitor Model 194X629G1 I

i I.