05000338/LER-1980-102-03, /3L-0:on 801211,auto Stop Oil Pressure Switch Calibr Procedure Would Allow Lower Min Valve than Tech Spec.Caused by Incorrect Procedure.Calibr Procedure Changed

/3L-0:on 801211,auto Stop Oil Pressure Switch Calibr Procedure Would Allow Lower Min Valve than Tech Spec.Caused by Incorrect Procedure.Calibr Procedure Changed

ML19351F393
Person / Time
Site:	North Anna
Issue date:	01/07/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19351F377	List: 05000338/LER-1980-102, Forwards LER 80-102/03L-0 05000338/LER-1980-102-03, /3L-0:on 801211,auto Stop Oil Pressure Switch Calibr Procedure Would Allow Lower Min Valve than Tech Spec.Caused by Incorrect Procedure.Calibr Procedure Changed
References
LER-80-102-03L, LER-80-102-3L, NUDOCS 8101120385
Download: ML19351F393 (2)

LER-1980-102, /3L-0:on 801211,auto Stop Oil Pressure Switch Calibr Procedure Would Allow Lower Min Valve than Tech Spec.Caused by Incorrect Procedure.Calibr Procedure Changed

Event date:
Report date:
3381980102R03 - NRC Website

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

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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

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On December 11, 1980, it was discovered that the auto stop oil pressure switch /

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calibration procedure associated with the low pressure reactor trip from

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turbine trip would previously have allowed a trip setpoint of 39 psig to be

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acceptable when the minimum value allowed by Tech Spec is 40 psig. All past

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calibrations were reviewed and verified to be 40 psig or greater, consequently,/

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reportable pursuant to T.S. 6.9.1.9.c.

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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This potential problem was caused by an incorrect procedure which was not

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revised when the requirement in the Technical Specification were issued. The /

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calibration procedure involved has been changed to correct the error in the

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trip setpoint tolerance.

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FACILITY METHOD OF STATUS

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NRC USE ONLY

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NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8101120 $

Virginia Electric and Power Company North Anna Power Station, Unit #1, Attachment: Page 1 of 1 Docket No. 50-338 Report No. LER 80-102/03L-0

Description of Event

Until recently revised, the calibration procedure for the turbine auto stop oil pressure switches (PS-LO609-4,5,6) permitted a trip setpoint tolerance of 45 psig 1 6 psig. On December 11, 1980, it was discovered that the procedure previously would have allowed a trip setting of 39 psig to be acceptable when the minimum value allowed by Technical Speci-fications (Table 2.2-1) is 40 psig. This discrepancy is reportable pursuant to T.S. 6.9.1.9.c.

Probable Consequences of Occurrence The affected pressure switches have a 2 out of 3 logic for detecting low auto stop oil pressure at less than 45 psig. The two redundant matrices provide for protective tripping of the reactor as a result of a turbine trip, for the backup trip to the turbine and for steam dump control. Because review of past switch calibrations revealed settings within the Technical Specification limit (never actually set at 39 psig), the health and safety of the general public were not affected.

Cause of Event

The ! 6 psig tolerance allowed by the procedure was derived by taking a 1/2% accurracy of the total switch sp'an.

The procedure was originally written prior to implementatin of Tech Specs and the discre-t pancy was not discovered after the requirements became effective. The calibration procedure involved has been changed to bring the trip setpoint tolerance within the Tech Spec limits.

Immediate Corrective Action

Revision was made to the calibration procedure changing the aute stop oil pressure switch trip setpoint tolerance from 45 t 6 psig to 45 1 2 psig.

Scheduled Corrective Action There are no schedr. led corrective action required.

Actions Taken to Prevent Recurrence The current review process will be improved to eliminate errors of this type.

Generic Implications l

This problem was generic to the Unit 2 procedure which has been corrected by a procedure change.

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