Event Notification Report for March 11, 2015
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
03/10/2015 - 03/11/2015
EVENT NUMBERS
50878
Power Reactor
Event Number: 50878
Facility: SEQUOYAH
Region: 2 State: TN
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MATT JUNGELS
HQ OPS Officer: VINCE KLCO
Region: 2 State: TN
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MATT JUNGELS
HQ OPS Officer: VINCE KLCO
Notification Date: 03/11/2015
Notification Time: 09:30 [ET]
Event Date: 03/11/2015
Event Time: 06:21 [EDT]
Last Update Date: 03/11/2015
Notification Time: 09:30 [ET]
Event Date: 03/11/2015
Event Time: 06:21 [EDT]
Last Update Date: 03/11/2015
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):
SCOTT SHAEFFER (R2DO)
SCOTT SHAEFFER (R2DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | A/R | Y | 100 | Power Operation | 0 | Hot Standby |
AUTOMATIC REACTOR TRIP DUE TO A NUCLEAR INSTRUMENTATION SIGNAL
"At [0621 EDT] on 3/11/2015, Sequoyah Unit 1 reactor/turbine automatically tripped.
"Following the reactor trip, all safety-related equipment operated as designed. Auxiliary Feedwater automatically initiated as expected from the Feedwater Isolation Signal.
"Unit 1 is currently being maintained in Mode 3 at NOT/NOP, approximately 547 F and 2235 psig, with auxiliary feedwater supplying decay heat removal via the steam generators and condenser steam dumps.
"The immediate cause of the trip was a Power Range Nuclear Instrumentation negative rate signal, caused by a malfunction in the rod control system. There was no associated work in progress related to this and all systems were normally aligned.
"Current Temperature and Pressure - 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, supplied from Off-Site power. There is no operational impact to Unit 2. Unit 2 continues to operate in Mode 1 at 100%.
"There was no impact on public health and safety. Post-trip investigation is in progress and planned restart timeline has not yet been determined.
"The licensee notified the NRC Resident Inspector."
"At [0621 EDT] on 3/11/2015, Sequoyah Unit 1 reactor/turbine automatically tripped.
"Following the reactor trip, all safety-related equipment operated as designed. Auxiliary Feedwater automatically initiated as expected from the Feedwater Isolation Signal.
"Unit 1 is currently being maintained in Mode 3 at NOT/NOP, approximately 547 F and 2235 psig, with auxiliary feedwater supplying decay heat removal via the steam generators and condenser steam dumps.
"The immediate cause of the trip was a Power Range Nuclear Instrumentation negative rate signal, caused by a malfunction in the rod control system. There was no associated work in progress related to this and all systems were normally aligned.
"Current Temperature and Pressure - 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, supplied from Off-Site power. There is no operational impact to Unit 2. Unit 2 continues to operate in Mode 1 at 100%.
"There was no impact on public health and safety. Post-trip investigation is in progress and planned restart timeline has not yet been determined.
"The licensee notified the NRC Resident Inspector."