ML19269D659

LER 79-016/03L-0 on 790506:during Surveillance Test, Isolator Condenser Isolation Sensor Setpoint a Measured Two Inches of Excess Water.Caused by Instrument Drift in Excess of Design Accuracy.Switch Was Recalibr & Put Back in Svc

ML19269D659
Person / Time
Site:	Oyster Creek
Issue date:	06/05/1979
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19269D657	List: ML19269D656 ML19269D659
References
LER-79-016-03L, LER-79-16-3L, NUDOCS 7906110195
Download: ML19269D659 (3)

Text

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8 6q 61 DOCKET NUMBER 68 EVENT OESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l On May 6', 1979 during a surveillance test for isolation condenser pipe g ,3 break isolation, "A" isolation condenser isolation sensor IBilAl set- g o,a point was found to be 29.0 inches of water instead of 27 0 inches as re- g ois I quired ky Tech. Specs. Table 3.1.1.H.2. The safety significance of this l o ,e l event i,s considered minimal since redundant sensor IB11A2 would have op- g

o,7 l erated at the required value to isolate "A" isolation condenser upon a l o,e high flow condition. l 80 g

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O d:g[ 17 19 l l-l l0 l1 l6 l l/l 0l3l lL l l-l 0l 21 22 23 24 20 27 28 29 30 31 32 ACTICN rCTUAE EFFECT S*UTDCL_ ATTACHMENT NPRD4 PRIL*E COMD. COYPONENT TAKEN AL, TION ON PLANT YETHOO HOURS SUBMITT ED FORM bub. SU PP LI E R MANUFACTURER l3JE lglaX l@ l23Z l@ lZ l@ J 0l 0 0l l 40 lYlg 41 lYjg 42 lNl@ l1l2l0 4lg 43 44 47 36 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS j

o l The cause of this occurrence is attributed to instrument drift in excess of design accuracy. Differential pressure indicating switch IBilAl was

, , l calibrated to operate at the required setpoint and placed back in  ;

, 3 l service. Differential pressure switch IBilAl will be retested during the [

week of June 4,1979  ;

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- - - ~( {- Madison Avenue at Punch Bowt Road Morristown New Jersey 07960 (201)455 4200 0YSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/79-16-3L Report D' ate June 5,'I979 Occurrence Date May 6, 1979 IJentification of Occurrence Tne setpoint of differential pressure indicating switch IBil Al was found to be less conservative than that specified in Table 3.1.1.H.2 of the Technical Specifications. This event is, considered to be a reportable occurreace as defined in the Technical Specifications, paragraph 6.9.2.B.I .

Conditions Prior to Occurrence The plant was in a cold shutdown condition.

Plant parameters at the time of the occurrence were:

Reactor coolant temperature - 177'F Reactor level 81" Yarway All control rods fully inserted Description of Occurrence On Sundgy, May 6,1979, at approximately 1233 hours0.0143 days <br />0.343 hours <br />0.00204 weeks <br />4.691565e-4 months <br />, "A" isolation condenser isolation sensor IB11 A1 setpoint was found to be less conservative than that established by ~the Technical Specifications. The condition was discovered during performance of a routine surveillance test for isolation condenser pipe break isolation.

Pressure Switch Desired Setpoint As As Designation (Head Correction Included) Found Left IBilAl 27" + 0" - 1" of H O 2 29 26 IBilA2 27" + 0" - 1" of H O 2 27 27 2255 113 J ' , ~ Ui L J/.9' .N L T' COTO'iny G a f.*emD9f O' the Genera! Puchc Utd.:>es System

.Preportable. Occurrence No. 50-219/79-16-3L Page 2 June 5, 1979 Apparent Cause of Occurrence it is noted that the instrument was not operating within its design accuracy and the apparent cause of this occurrence is attributed to instrument drif t.

Analysis of Occurrence Differential pressure indicating switch IBilAl senses a high flow condition, which would indicate a pipe break, in the "A" isolation condenser condensate return ti.ne. Upon sensing a high flow condition, sensor IBilAl wouldSensor complete the logic circuit required to isolate the "A" isolation condenser.

IBilAl wculd have operated as required, but at a less conservative value than that required by the Technical Specifications.

The safety significance of this event is considered to be minimal since the redundant sensor IB11A2 would have operated at the required value, to isolate "A" isolation condenser upon a high flow condition.

Correc tive Action Differential pressure indicating switch IB11A1 was calibrated to operate at the required value and placed back into service. Differential pressure switch IB11 A2 will be retested during, the week of June 4,1979 to determine if thei setpoint is operating within the design accuracy. Additionally, an invest ga-tion of the history of the surveillance test results pertaining to the pipe break sensors indicates that there are no generic drift problems associated with them.

Failure Data IB11A1 -- ITT Barton Monterey, California Sertal Number: 278-964}} jj4 S.W.P.: 1500 Differential Pressure: 0-60 WC

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