ML20085M385

Special Rept:On 950528,RCS Was Filled to Solid Water Conditions During start-up Activities Following Recent Refueling Outage

ML20085M385
Person / Time
Site:	North Anna
Issue date:	06/22/1995
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
95-297, NUDOCS 9506290166
Download: ML20085M385 (2)

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l VIRGINIA ELECTRIC AND PowcH COMI*ANY

. Ricnnown,VIItGINIA 20061 June 22, 1995 l U. S. Nuclear Regulatory Commission Serial No.95-297 l Attention: Document Control Desk NAPS /MPW/MAE R4 Washington, D. C. 20555 Docket No. 50-339 License No. NPF-7 Gentleman:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT 2 PRESSURIZER PORV SPECIAL REPORT Pursuant to North Anna Technical Specification 6.9.2.f a Special Report is hereby submitted for a low-temperature overpressure condition that resulted in one of the pressurizer (PZR) power operated relief valves (PORVs) lifting to mitigate a reactor coolant system (RCS) low-temperature overpressure transient.

On May 28,1995, with Unit 2 in Mode 5, cold shutdown, the RCS was filled to solid water conditions during start-up activities following the recent refueling outage. The reactor coolant loops were filled using a new loop vacuum fill method to 1) ensure the RCS is as full as possible,2) limit oxygen,3) prevent the need to cycle the reactor coolant pumps (RCPs) in order to " sweep" entrained air from the loops, and 4) prevent the need for RCS depressurization and venting evolutions.

The "A" RCP was started to facilitate heat-up of the RCS and sweep entrained air out of the loops. Upon start of the pump, an expected rapid decrease in RCS pressure was indicated on the "A" loop, and control room personnel initiated actions to increase RCS pressure. However, as a result of the loop vacuum fill method, only a very small amount of entrained air was in the primary system. It was quickly realized that the indicated pressure decrease was due to the differential pressure being created by the RCP start and the location of the pressure transmitter. The letdown pressure control valve was in the process of being opened to reduce RCS pressure when the pressurizer PORV cycled open. The RCS pressure was lowered using the letdown pressure control valve and stabilized at 325 psig. The highest RCS wide range pressure noted was 378 psig versus the Technical Specification lift setpoint of 375 psig. The controlling procedures and plant simulator training will be reviewed and revised as necessary.

This Special Report has been reviewed by the Station Nuclear Safety and Operating Committee and will be provided to the Management Safety Review Committee.

Should you have any questions regarding this report, please contact us.

Very truly yours, J cf James P. O'Hanlon Senior Vice President - Nuclear 27001a 9506290166 950622 9 yi O DR ADOCK 0500

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cc: U.S. Nuclear Regulatory Commission l Region ll 101 Marietta Street, N.W.

Suite 2900 Atlanta, Georgia 30323 R. D. McWhorter NRC Senior Resident Inspector g North Anna Power Station l

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