05000219/LER-1980-060-03, /03L-0:on 801211,during Routine Testing,Pipe Break Sensors for Isolation Condenser Condensate Return Lines Tripped Higher than Tech Spec.Caused by Instrument Drift. Switches Reset

/03L-0:on 801211,during Routine Testing,Pipe Break Sensors for Isolation Condenser Condensate Return Lines Tripped Higher than Tech Spec.Caused by Instrument Drift. Switches Reset

ML19340E792
Person / Time
Site:	Oyster Creek
Issue date:	01/09/1981
From:	Crosby P JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19340E791	List: 05000219/LER-1980-060, Forwards LER 80-060/03L-0 05000219/LER-1980-060-03, /03L-0:on 801211,during Routine Testing,Pipe Break Sensors for Isolation Condenser Condensate Return Lines Tripped Higher than Tech Spec.Caused by Instrument Drift. Switches Reset
References
LER-80-060-03L, LER-80-60-3L, NUDOCS 8101150695
Download: ML19340E792 (3)

LER-1980-060, /03L-0:on 801211,during Routine Testing,Pipe Break Sensors for Isolation Condenser Condensate Return Lines Tripped Higher than Tech Spec.Caused by Instrument Drift. Switches Reset

Event date:
Report date:
2191980060R03 - NRC Website

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OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/80-60/3L Report Date January 9, 1981 Occurrence Date Decenber 11, 1980 Identification of occurrence Isolation Condancar (condensate) pipe bre:k sensors IB11Al, IB11A2, IBilB1 and IBilB2 tripped at a value greater than th t specified in the Technical Specifica-tions, Table 3.1.1 Iten H.2.

This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6.9.2.b(1).

Conditions Prior to Occurrence The plant was operating at steady state power. Major plant parameters at the time of occurrence were:

Power:

Core 1883 MWt Electrical 652 MWe 4

Flow:

Recirculation 15.5 x 10 p Feedwater 7.0 x 106 lb/hr Description of Occurrence On Thursday, Decenber 11,1980 (Condenser "A") and Friday, Der 12, 1980 (Condenser "B"), while perfonning the " Isolation Condenser Isolation Test and

('alibration", the trip points for the condensate pipe break sensors were found to be less conservative than that specified in the Technical Specifications.

Survai11ance testing on the switches yielded the following data:

Pressure Switch Designation Desired As Found As left Setpoint Trip Point Trip Point IB11A1 5 27" H 31.8"HM 26.7 TR11 A2

- 27" H 28.5" H 26.3 IBllB1 5-27" 30.0" H 26.8 IB11B2 i 27" H 30.0" H2 26.7

Reportable Occurrence Page 2 Report No. 50-219/80-60/3L Apparent Cause of Occurrence The cause of the occurrence is attributed to instrument drift.

Analysis of Occtumm The Isolation Condenser pipe break sensors are designed to provide protection in the event of a pipe break, occurring in the steam or condensate lines to the condensers, outside the containment. The flow sensors are located on pipe elbows inside the containmant. During normal plant operation the Isolation Condensers are in a standby condition with the condensate return lines isolated by nonnally closed containment isolation valves.

In the event of a pipe break occurring outside the coneninmant during isolation condenser system operation, the steam line flow sensors (which were operating within technical specification litrits) would have actuated to isolate the affected condenser in the required manner. The condensate line flow sensors also would have actuated but at a slightly higher flow correspnding to the "as found" trip point.

Corrective Action

The switches were adjusted to trip within the Technical Specifications limit of 27" of H O differential pressure as part of the test procedure. An engineering 2

study is currently underway to investigate the problem of drifting associated with these snap-action type pressure switches. After consideration of the frequency of occurrence of set point drift associated with the ITr Barton differential pressure indicating switches with snap-action, the PORC re,- h replacenent of the devices with a more suitable, qualified model.

Failure Data ITI Barton Model - 288A Indicating Pressure Switch Range: 0-60" H O 2

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