ML20096E037

Special Rept:On 920414,overpressure Protection Sys Actuated When Pressurizer PORV Opened.Caused by Unplanned Increase in RCS Pressure.Operations Personnel Coached on Importance of Properly Controlling Plant Parameters

ML20096E037
Person / Time
Site:	North Anna
Issue date:	05/14/1992
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
92-323, NUDOCS 9205190030
Download: ML20096E037 (2)

Text

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YlHOINIA MI.l!CTitIC AND POWl H CO)!!%NY N ICil p!ON D,Viltu tNI A 2132 61 May J 4, 1992 -

U. S. Nuclear Regulatory Commission Serial No.92-323 Attn. Document Control Desk NAPS /JRPffAH: R3

Washin0 ton, D.C. 20555 Docket No.: 50-339 License No.: NPF-7 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT 2 SPECIAL REPORT; INADVEBTENT ACTUATION OF THE OVERPRESSURE PROTECTIOE SYSTEM. DURING SOLID WATER OPERATIONS On April 14,1992, North Anna Power Station' Unit 2 experienced an actuation of the Overpressure Protection System when a Pressurizer. Power Operated Relief Valve opened due to an unplanned increase in Reactor Coolant System Pressure. This event is reportable as a Special Report pursuant to Technical Specification 3.4.9.3

Limiting Condition for Operation (Action "c"), and Technical Specification 6.9.2.

At the time of the event Unit 2 was in Mode 5, solid water conditions, with the Reactor Coolant Pumps secured and the unit being prepared for a return to power operations following a scheduled refueling outage. .The Reactor' Coolant System temperature was being maintained at approximately 130 F'and the operators were; stabilizing system pressure at. 335 psig, after securing a Reactor Coolant Pump during the filling and venting activities of the Reactor Coolant System. <

At 11:19 am, the Reactor Coolant System pressure drifted upward and one Pressurizer Power Operated Relief Valve, 2-RC-PCV-24550, actuated to reduce the Reactor

, Coolant System pressure. The operators took immediate corrective actions to lower and stabilize the Reactor Coolant System Pressurizer pressure below the Pressurizer Power Operated Relief Valve lift setpoint.

A subsequent investigation revealed a sharp Reactor Coolant System pressure drop 4

of approximately 20 psig when the Pressurizer Power Operated Relief Valve opened.

The Safety Parameter Display System indicated that 2-RC-PCV-24550 had openeo for less than four seconds. Operator inattention and failure to stabilize Reactor-Coolant System pressure in accordance with procedures was determined to be the

~)ot cause, i

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PDR- ADOCK 05o00339 6 , . . _ . __

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Docket No.: 50 339 Serial No. 92 323 Page 2 of 2 Additional corrective actions to preclude a similcr event include coaching the operations personnel responsible for maintaining Reactor Coolant System pressure on the importance of properly controlling plant parameters. Also, additional emphasis on Reactor Coolant System pressure control during solid water operations will be included in the Licensed Operator Requalification Program.

During the event, the Overpressure Protection System was operable in accordance with Technical Specification 3.4.9.3 and Pressurizer Power Operated Relief Valve responded as designed, thus providing overpressure protection for the Reactor Coolant System at the low system temperatures. Therefore, the health and safety of the general public was not affected.

If you have any further questions, please contact us.

Very truly yours, r, . . ,

[f y W. L. Stewart Senior Vice President Nuclear Attachment pc: U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, N.W.

Suite 2900 Atlanta, Georgia 30323 Mr. M. S. Lesser NRC Senior Resident inspector North Anna Power Station i

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