October 6th, 2011 – NRC Event Notification 47321 – Prairie Island RCS (AUDIO)

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Enformable Status Update – Prairie Island October 6th, 2011 Notification Report 47321

Power Reactor Event Number: 47321
Region: 3 State: MN
Unit: [ ] [2] [ ]
RX Type: [1] W-2-LP,[2] W-2-LP
Notification Date: 10/05/2011
Notification Time: 15:50 [ET]
Event Date: 10/05/2011
Event Time: 07:27 [CDT]
Last Update Date: 10/05/2011
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(B) – POT RHR INOP
Person (Organization):
Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
2 N N 0 Hot Shutdown 0 Hot Shutdown

Event Text

TWO LOOPS OF REACTOR COOLANT SYSTEM (RCS) WERE DECLARED INOPERABLE”Unit 2 was shut down at 1048 CDT on October 4, 2011 due to 22 Reactor Coolant Pump (RCP) low seal leak off flow. At 0727 CDT on October 5, 2011 with Unit 2 in Mode 4 and 22 RCP secured, 21 RCP was also secured due to low seal leak off flow.”It was determined that the station would not consider RHR [residual heat removal] available for decay heat removal per Technical Specification (TS) due to a procedural issue related to component cooling shutdown lineups. RCS temperature is being maintained stable in Mode 4 between 320 and 340 degrees Fahrenheit using natural circulation and the steam dump to the condenser. No operations were permitted that would have caused introduction into the RCS, coolant with boron concentration less than required to meet the Shutdown Margin.”At approximately 1329 CDT 21 RCP was restarted after the flow transmitters were vented and 21 RCP seal leak off flow was determined to be acceptable. The RHR procedural issue has been resolved.

“Per TS LCO 3.4.6, ‘Two loops consisting of any combination of RCS loops and residual heat removal (RHR) loops shall be OPERABLE, and one loop shall be in operation.’ This condition is reportable as an event or condition that could have prevented fulfillment of a safety function under 10CFR 50.72(b)3)(v)(B).”

During this event, RHR could not be credited because the utility was not able to valve in component cooling water to a SFP heat exchanger due to procedural issues. With the restart of 21 RCP and shutdown cooling water alignment, TS 3.6.4 A and B statements have been met and exited. 21 RCP loop in operation and 22 RHR is operable and can be aligned for shutdown cooling. Both Unit 2 EDG’s are available and offsite power is normal electrical lineup. The licensee is no longer in any TS LCO statements.

The NRC Resident Inspector has been notified.

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