Event Notification Report for February 24, 2013
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
02/23/2013 - 02/24/2013
Power Reactor
Event Number: 48778
Facility: SEQUOYAH
Region: 2 State: TN
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MATTHEW LEENERTS
HQ OPS Officer: VINCE KLCO
Region: 2 State: TN
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MATTHEW LEENERTS
HQ OPS Officer: VINCE KLCO
Notification Date: 02/24/2013
Notification Time: 15:20 [ET]
Event Date: 02/24/2013
Event Time: 12:05 [EST]
Last Update Date: 02/24/2013
Notification Time: 15:20 [ET]
Event Date: 02/24/2013
Event Time: 12:05 [EST]
Last Update Date: 02/24/2013
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
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
GERALD MCCOY (R2DO)
GERALD MCCOY (R2DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | M/R | Y | 25 | Power Operation | 0 | Hot Standby |
MANUAL REACTOR TRIP DUE TO LOSS OF CONDENSER VACUUM INDICATION
"On February 24, 2013 at 1205 [EST] with reactor power at 25% and the turbine offline, a manual reactor trip for Sequoyah Unit 2 was initiated due to loss of condenser vacuum indication causing closure of condenser steam dumps, opening of the Steam Generator Atmospheric Relief Valves, and lowering hotwell level resulting in imminent loss of hotwell pumps. The cause of the event was determined to be a faulty test connection on B Condenser vacuum pressure switch.
"During the event, steam pressure rose to the setpoint for the first Steam Generator code safety valve (1064 psig). [The safety valve opened, then reseated].
"Following the reactor trip, all safety related equipment operated as designed. Auxiliary feedwater actuated as expected on loss of the operating main feedwater pumps. The reactor trip was uncomplicated.
"Unit 2 is currently being maintained in Mode 3 at NOP/NOT [Normal Pressure and Temperature], with auxiliary feedwater supplying the steam generators and maintaining level at approximately 33% narrow range.
"Method of decay heat removal is via atmospheric reliefs to the atmosphere. Current RCS conditions: temperature [is] 547 degrees F and stable. Pressure [is] 2235 psig and stable. [There is] no indication of any primary/secondary leakage. All rods are inserted. Electrical alignment is normal and supplied from offsite power. [There is] no impact to Unit 1. Unit 1 is operating at 100% power / Mode 1.
"There was no impact on public health and safety. Post-trip investigation is in progress and planned restart is 02/25/2013. [The licensee plans a press release.]"
The licensee notified the NRC Resident Inspector.
"On February 24, 2013 at 1205 [EST] with reactor power at 25% and the turbine offline, a manual reactor trip for Sequoyah Unit 2 was initiated due to loss of condenser vacuum indication causing closure of condenser steam dumps, opening of the Steam Generator Atmospheric Relief Valves, and lowering hotwell level resulting in imminent loss of hotwell pumps. The cause of the event was determined to be a faulty test connection on B Condenser vacuum pressure switch.
"During the event, steam pressure rose to the setpoint for the first Steam Generator code safety valve (1064 psig). [The safety valve opened, then reseated].
"Following the reactor trip, all safety related equipment operated as designed. Auxiliary feedwater actuated as expected on loss of the operating main feedwater pumps. The reactor trip was uncomplicated.
"Unit 2 is currently being maintained in Mode 3 at NOP/NOT [Normal Pressure and Temperature], with auxiliary feedwater supplying the steam generators and maintaining level at approximately 33% narrow range.
"Method of decay heat removal is via atmospheric reliefs to the atmosphere. Current RCS conditions: temperature [is] 547 degrees F and stable. Pressure [is] 2235 psig and stable. [There is] no indication of any primary/secondary leakage. All rods are inserted. Electrical alignment is normal and supplied from offsite power. [There is] no impact to Unit 1. Unit 1 is operating at 100% power / Mode 1.
"There was no impact on public health and safety. Post-trip investigation is in progress and planned restart is 02/25/2013. [The licensee plans a press release.]"
The licensee notified the NRC Resident Inspector.
Power Reactor
Event Number: 48781
Facility: FORT CALHOUN
Region: 4 State: NE
Unit: [1] [] []
RX Type: (1) CE
NRC Notified By: KLINT KUDLACEK
HQ OPS Officer: STEVE SANDIN
Region: 4 State: NE
Unit: [1] [] []
RX Type: (1) CE
NRC Notified By: KLINT KUDLACEK
HQ OPS Officer: STEVE SANDIN
Notification Date: 02/25/2013
Notification Time: 16:01 [ET]
Event Date: 02/24/2013
Event Time: 17:00 [CST]
Last Update Date: 02/25/2013
Notification Time: 16:01 [ET]
Event Date: 02/24/2013
Event Time: 17:00 [CST]
Last Update Date: 02/25/2013
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
Person (Organization):
DON ALLEN (R4DO)
DON ALLEN (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | N | 0 | Cold Shutdown | 0 | Cold Shutdown |
INVERTERS POTENTIALLY INOPERABLE DURING EMERGENCY DIESEL GENERATOR OPERATION
"During a review of the plant inverters, it has been determined that the inverters may not have been operable. The inverters were replaced during the 2008 refueling outage. It appears that either the modification did not recognize that the diesel frequency range is wider than the new inverters, or did not recognize its consequence. Consequently, when the diesel is supplying power to the buses and loads are being sequenced onto the bus, the bus frequency exceeds the inverter frequency range. This causes inverter voltage transients. Operation of the inverters has been modified to improve plant reliability. This issue was discovered during scheduled plant testing of the electrical system."
The licensee informed the NRC Resident Inspector.
"During a review of the plant inverters, it has been determined that the inverters may not have been operable. The inverters were replaced during the 2008 refueling outage. It appears that either the modification did not recognize that the diesel frequency range is wider than the new inverters, or did not recognize its consequence. Consequently, when the diesel is supplying power to the buses and loads are being sequenced onto the bus, the bus frequency exceeds the inverter frequency range. This causes inverter voltage transients. Operation of the inverters has been modified to improve plant reliability. This issue was discovered during scheduled plant testing of the electrical system."
The licensee informed the NRC Resident Inspector.