05000317/LER-1981-055-03, /03L-0:on 810701,pressurizer Pressure Channel 2E & Subcooled Margin Monitor 11 Removed from Svc & Reactor Protection Sys Channel B Trip Units Bypassed to Check Deviation Between Channels.Caused by Instrument Drift

/03L-0:on 810701,pressurizer Pressure Channel 2E & Subcooled Margin Monitor 11 Removed from Svc & Reactor Protection Sys Channel B Trip Units Bypassed to Check Deviation Between Channels.Caused by Instrument Drift

ML20010A393
Person / Time
Site:	Calvert Cliffs
Issue date:	07/31/1981
From:	Lagiewski J, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010A391	List: 05000317/LER-1981-055, Forwards LER 81-055/03L-0 05000317/LER-1981-055-03, /03L-0:on 810701,pressurizer Pressure Channel 2E & Subcooled Margin Monitor 11 Removed from Svc & Reactor Protection Sys Channel B Trip Units Bypassed to Check Deviation Between Channels.Caused by Instrument Drift
References
LER-81-055-03L, LER-81-55-3L, NUDOCS 8108110389
Download: ML20010A393 (2)

LER-1981-055, /03L-0:on 810701,pressurizer Pressure Channel 2E & Subcooled Margin Monitor 11 Removed from Svc & Reactor Protection Sys Channel B Trip Units Bypassed to Check Deviation Between Channels.Caused by Instrument Drift

Event date:
Report date:
3171981055R03 - NRC Website

text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION (7 77)

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60 61 DOCK ET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h lo [2l l At 0750 and 0845 ESFAS Ch ZE Pressurizer Pressure (Pzr Press) and 11 Sub-1 io i3i l cooled Margin Monitor were removed from se.vice and RPS Ch B trip units l

1O i4 l l for Hi Pzr Press and Thermal Margin / Low Pressure were bypassed to inves-1 iO isi l tigate a >.16 volt deviation between channels (T.S. 3.3.2.1, 3.3.1.1, 1

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3.3.3.6).

All instruments were returned to service at 1445. On 7-9-81 l

l 0 l 71 l the isolating transmitter was adjusted and the loop checked satisfac-1 iOiRi i torily. All redundant channels remained operable during this event.

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36 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 111011 Narra.' rance outout of isolatine transmitter 1-PY-102B (RIS #XSC-1302-I [i li l l 80618) had drif ted low by an amount equivalent to 35 psi. On 7-1-81.

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Ch B High Pressure Trip and Pre-trip setpoints were lowered to account l

lii3ll for the signal offset. On 7-9-81, the PY and setpoints were readjusted.

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No preventive action is deemed necessary as this is the first such event.

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NAME OF PREPARER

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LER No.

81-55/3L DOCKET NO.

50-317 LICENSE NO.

DPR-53 EVENT DATE 07-01-81 REPORT DATE 07-31-81 ATTACHMENT EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (CONT'D)

At 0750, during normal operation, ESFAS Channel "ZE" Pressurizer Pressure (Pzr.

Press.) was removed from service to investigate a >.16 volt deviation between channels (T.S. 3.3.2.1). At 0845, RPS Channel "B" trip units for Hi Pressurizer-Pressure and Thermal Margin / Low Pressure were bypassed and #11 Subcooled Margin Monitor placed out of service for additional troubleshooting (T.S. 3.3.1.1 and 3.3.3.6). It was surmised that the Pressurizer Pressure Transmitter had zero l

shif ted, therefore, the Pressurizer Pressure Hi trip setpoint was lowered 35 psi as an interim measure until the transmitter could be checked.- All instruments were -

1 returned to service at 1445. On 7-9-81, during the next outage, the Pressurizer Pressure Transmitter was checked and found to be in calibration. Upon further investigation it was found that the E/E isolator (1-PY-102-B) was out of adjustment. Span and zero adjustments were made, the loop checked l

satisfactorily, and all instruments returned to service. The Hi Pressurizer Pressure trip setpoint was returned to normal on 7-11-81. ~ All redundant channels remained operable during this event, however, #12 Subcooled Margin Monitor remained out of service. This is not a repetitive event.

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