United States Nuclear Regulatory Commission - Protecting People and the Environment

Event Notification Report for June 29, 2012

U.S. Nuclear Regulatory Commission
Operations Center

Event Reports For
06/28/2012 - 06/29/2012

** EVENT NUMBERS **


48053 48055

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Power Reactor Event Number: 48053
Facility: POINT BEACH
Region: 3 State: WI
Unit: [ ] [2] [ ]
RX Type: [1] W-2-LP,[2] W-2-LP
NRC Notified By: RUSS PARKER
HQ OPS Officer: JOHN SHOEMAKER
Notification Date: 06/28/2012
Notification Time: 01:06 [ET]
Event Date: 06/27/2012
Event Time: 20:46 [CDT]
Last Update Date: 06/28/2012
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
NICK VALOS (R3DO)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
2 M/R Y 100 Power Operation 0 Hot Standby

Event Text

MANUAL REACTOR TRIP DUE TO 100% LOAD REJECT

"Unit 2 Manual Reactor Trip was actuated due to indications of a 100% Load Rejection. The cause of the Load Rejection is not known at this time. All Control Rods are fully inserted. The RCS is being cooled by forced flow (reactor coolant pumps). Secondary heat sink is being provided by the condenser steam dumps utilizing the main feedwater system. The auxiliary feedwater system actuated based on low steam generator level, but has since been secured. There were no unexpected (inconsistent with nature of trip) pressure or level transients. Off site power remains available. No release occurred nor is ongoing. Emergency Core Cooling Systems did not actuate. No unexpected isolations occurred. Emergency Plan entry was not required."

The plant is stable at normal temperature and pressure. The electrical system is in a normal offsite power alignment. The Unit 2 Reactor Trip had no effect on Unit 1 which continues to operate at 100% power.

The licensee has notified the NRC Resident Inspector.

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Power Reactor Event Number: 48055
Facility: SUSQUEHANNA
Region: 1 State: PA
Unit: [1] [2] [ ]
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: DARVIN DUTTRY
HQ OPS Officer: JOE O'HARA
Notification Date: 06/28/2012
Notification Time: 20:44 [ET]
Event Date: 06/28/2012
Event Time: 13:53 [EDT]
Last Update Date: 06/28/2012
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
ANNE DeFRANCISCO (R1DO)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
1 N N 0 Cold Shutdown 0 Cold Shutdown
2 N Y 100 Power Operation 100 Power Operation

Event Text

LOSS OF ONE OF TWO OFFSITE POWER SOURCES

"At 1353 EDT on 06/28/2012, Susquehanna Steam Electric Station experienced a loss of power from one of two offsite power sources when transformer 20 shutdown automatically. All ESS [Engineered Safeguards System] electrical busses fed by this transformer automatically transferred to the other offsite power source (transformer 10). Additionally, startup bus 20, which is normally fed from transformer 20, automatically transferred to transformer 10.

"On each unit, multiple system containment isolation valves closed as a result of the electrical transient. Operators were able to reset and restore each system. On unit one, residual heat removal (RHR) shutdown cooling ceased operation during the transient. Shutdown cooling was restored within one hour by control room operators in accordance with off-normal procedures. Unit two remained at 100% power throughout the event.

"This incident is being reported as an unplanned actuation of systems that mitigate the consequences of significant events per 10 CFR 50.72(b)(3)(iv)(A)."

The licensee is in a 72 hour LCO on Unit 2 as a result of the loss of offsite power. All emergency diesels generators are available. The licensee is investigating the cause of the transformer 20 shutdown.

The NRC Resident Inspector and the Pennsylvania Emergency Management Agency (PEMA) have been notified.

Page Last Reviewed/Updated Friday, June 29, 2012
Friday, June 29, 2012