05000338/LER-1981-029-03, /03L-0:on 810422,pressure Transmitter PT-LM-100B Was Found Out of Calibr in Nonconservative Direction.Caused by Instrument Drift.Channel Recalibr

/03L-0:on 810422,pressure Transmitter PT-LM-100B Was Found Out of Calibr in Nonconservative Direction.Caused by Instrument Drift.Channel Recalibr

ML19345H434
Person / Time
Site:	North Anna
Issue date:	05/15/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19345H432	List: 05000338/LER-1981-029, Forwards LER 81-029/03L-0 05000338/LER-1981-029-03, /03L-0:on 810422,pressure Transmitter PT-LM-100B Was Found Out of Calibr in Nonconservative Direction.Caused by Instrument Drift.Channel Recalibr
References
LER-81-029-03L, LER-81-29-3L, NUDOCS 8105200282
Download: ML19345H434 (3)

LER-1981-029, /03L-0:on 810422,pressure Transmitter PT-LM-100B Was Found Out of Calibr in Nonconservative Direction.Caused by Instrument Drift.Channel Recalibr

Event date:
Report date:
3381981029R03 - NRC Website

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p' U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

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DOCKET NUMBER EVENT DATE REPORT DATE EVENT. DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On April 22, 1981 during Mode 1 operation, pressure transmitter PT-LM-100B was /

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/_ found to be out of calibration in the non-conservative direction. This error /

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would have caused the containment spray actuation signal to initiate 1.7 psia /

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higher than the remaining channels. However, the three remaining channels

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were functional throughout this period. Therefore, the health and safety of

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the public were not affected. This item is reportable purcuant to T.S.

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6.9.1.9.b, c.

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4' PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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This event was caused by instrumee drift in the pressure transmitter. The

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channel was cecalibrated and returned to service.

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OBSERVATION

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NRC USE ONLY

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NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 l 81052ang >

- y Virginia Electric and Power Company North Anna Power Station, Unit #1 Attachment: Page 1 of 2 Docket No. 50-338 Report No. LER 81-029/03L-0

Description of Event

The actuation point for containment pressure transmitter 1-PT-LM-100B was found to be above the allowable value specified in T.S. 3.3.2.1.

The containment pressure transmitter drifted lower by a total value of 1.7 psi.

This would have caused the actuation point for the safeguards signals to energize 1.7 psi higher than the remaining chanaels.

It was discovered,~during the investigation of this event, that the applicable periodic tests specified trip setpoints and allowable values inconsistent with the Technical Specification values. In the cases of the containment high (17 psia) and the intermediate high-high (17.8 psia) setpoints, the periodic test acceptance criteria had an allowable error of.5 psia higher than the Technical Specification limit. The previous periodic test data was immediately reviewed to ensure that as found data was within the Technical Specification limits.

Probable Consequences of Occurrence The containment pressure channels are used for the initiation of the Engineered Safety Feature System. This system actuates containmettt isolation (phase A & B), main steam line isolation, containment spray, and Safety Injection signals. Since the maximum instrument drift observed resulted in actuation only 0.2 psia higher than allowable on one channel and the other three channals remained operable, the health and safety of the public were not affected.

In addition, at no time were setpoints outside Technical Specification allowable values actually utilized.

Cause of Event

The cause of tne transmitter low readings was inatrument drift. The error in the periodic test procedure acceptance criteria was caused by the failure to update the periodic test when a revision to the Technical Specifications was made.

Immediate Corrective Action

l The faulty channel was placed in a blocked condition and the remaining channels demonstrated operable within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. The low indication for PT-LM-100B was corrected by recalibrating the transmitter.

The previous calibration data for the remaining unit 1 and 2 transmitters was reviewed to ensure that as-found data was within Technical Specification allowable values, Scheduled Corrective Action The appropriate unit I and 2 periodic tests will be revised to reflect the Technical Specification trip setpoints and allowabit values.

Actions Taken to Prevent Recurrence In the future, Technical Specification changes will be routed through the Periodic Test Engineer for his review to ensure that the

Attachment: Page 2 of 2 appropriate changes to periodic tests are made in a timely manner. -

Generic Implications There are no generic implications associated with this event.

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