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Event Notification Report for June 18, 2010

U.S. Nuclear Regulatory Commission
Operations Center

EVENT REPORTS FOR
06/17/2010 - 06/18/2010

EVENT NUMBERS
46025

Power Reactor
Event Number: 46025
Facility: PALO VERDE
Region: 4     State: AZ
Unit: [1] [] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: BRIAN FERGUSON
HQ OPS Officer: DONG HWA PARK
Notification Date: 06/18/2010
Notification Time: 12:04 [ET]
Event Date: 06/18/2010
Event Time: 08:08 [MST]
Last Update Date: 06/18/2010
Emergency Class: UNUSUAL EVENT
10 CFR Section:
50.72(a) (1) (i) - EMERGENCY DECLARED
Person (Organization):
WILLIAM JONES (R4DO)
MIKE CHEOK (NRR)
WILLIAM GOTT (IRD)
ART HOWELL (R4)
JACK GROBE (NRR)
Power Reactor Unit Info
Unit SCRAM Code RX Crit Initial PWR Initial RX Mode Current PWR Current RX Mode
1 N Y 100 Power Operation 25 Power Operation
Event Text
UNUSUAL EVENT DECLARED DUE TO DAMAGED ENERGIZED EQUIPMENT

"On June 18, 2010, at approximately 0807 MST, a manual turbine trip was initiated due to loss of cooling for Main Transformer X01C. The power supplies for the transformer cooling system was lost due to an inadvertent actuation of the transformer fire protection deluge system. The damage to the energized equipment met the definition for an Emergency Action Level HU 2.2. Based on HU 2.2 the Unit 1 Shift Manager declared a Notification of an Unusual Event (NOUE) at 0808 MST applicable to Palo Verde Unit 1 only.

"The manual trip of the turbine initiated a Reactor Power Cutback Large Load Rejection actuation which was successful. The reactor is stable at 25% with Heat Removal via main feedwater and steam bypass to main condenser. A down power to approximately 12% power is being planned.

"No anomalies were noted during the manual turbine trip. [There is] no release in progress and no safety systems actuations were required."

Palo Verde Unit 1 is in a normal post-trip electrical lineup. State and local authorities have been notified as well as the NRC Resident Inspector.

* * * UPDATE FROM BRIAN FERGUSON TO DONG PARK @ 1333 EDT ON 6/18/10 * * *

The licensee terminated the Unusual Event at 1030 MST. The reactor remains stable at approximately 12% power, and heat removal is via main feedwater and steam bypass to the main condenser.

Notified IRD (Gott), NRR EO (Cheok), R4DO (Jones), DHS (Inzer) and FEMA (Hollis).