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Event Notification Report for April 20, 2004

U.S. Nuclear Regulatory Commission
Operations Center

Event Reports For
04/19/2004 - 04/20/2004

** EVENT NUMBERS **


40684

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Power Reactor Event Number: 40684
Facility: NINE MILE POINT
Region: 1 State: NY
Unit: [ ] [2] [ ]
RX Type: [1] GE-2,[2] GE-5
NRC Notified By: DAVE RICHARDSON
HQ OPS Officer: ARLON COSTA
Notification Date: 04/18/2004
Notification Time: 23:45 [ET]
Event Date: 04/18/2004
Event Time: 18:30 [EDT]
Last Update Date: 04/18/2004
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
BRIAN MCDERMOTT (R1)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
2 N N 0 Cold Shutdown 0 Cold Shutdown

Event Text

RESIDUAL HEAT REMOVAL SYSTEM ISOLATION DUE TO A RISE IN REACTOR PRESSURE

"At 1830 hours on 18 April 2004, Nine Mile Point Unit 2 was restoring from reactor pressure vessel leakage test.

"Reactor pressure was ~82 psi, temperature ~178 degrees, reactor level was solid with both reactor recirculation pumps running in slow speed per the leak test procedure.

" 'B' residual heat removal system was being warmed up in preparation for going in to service. Reactor water cleanup reject from the vessel was secured to maintain RPV [Reactor Pressure Vessel] pressure stable in order to provide driving head for flow through the residual heat removal discharge line to radwaste. The line is warmed up from the reactor, back through the Shutdown cooling isolation valve, to radwaste prior to placing shutdown cooling in service. When warm-up criteria are met, the operating procedure directs securing flow.
When flow was secured, this effectively isolated the solid reactor vessel, resulting in a rise in reactor pressure. Pressure peaked at ~146 psi before operators established reactor water cleanup reject flow.

"When RPV pressure reached 128 psi, the residual heat removal system isolation was automatically initiated as designed. The shutdown cooling injection valve, which was open to support piping warm-up, closed as designed. All other shutdown cooling valves were closed prior to the event per the warm-up lineup."

RPV is currently depressurized with shutdown cooling in service. All systems are functioning as expected.

The licensee notified the NRC Resident Inspector.

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