Event Notification Report for December 01, 2023
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
11/30/2023 - 12/01/2023
Power Reactor
Event Number: 56877
Facility: South Texas
Region: 4 State: TX
Unit: [2] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Mark Hamilton
HQ OPS Officer: Adam Koziol
Region: 4 State: TX
Unit: [2] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Mark Hamilton
HQ OPS Officer: Adam Koziol
Notification Date: 12/02/2023
Notification Time: 12:47 [ET]
Event Date: 12/02/2023
Event Time: 06:10 [CST]
Last Update Date: 12/02/2023
Notification Time: 12:47 [ET]
Event Date: 12/02/2023
Event Time: 06:10 [CST]
Last Update Date: 12/02/2023
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
Person (Organization):
Taylor, Nick (R4DO)
Taylor, Nick (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
SPECIFIED SYSTEM ACTUATION - AUTO START OF EMERGENCY DIESEL GENERATOR
The following information was provided by the licensee via email:
"At 0610 CST on 12/2/2023, with Unit 2 in Mode 1 at 100 percent power, the South Texas Project switchyard south electrical bus was de-energized. Emergency diesel generator (EDG) '22' automatically started in response to the loss of offsite power on the train 'B' engineered safety feature (ESF) electrical bus.
"This event is reportable under 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in the valid actuation of an emergency AC electrical power system (50.72(b)(3)(iv)(B)(8)).
"All required loads were successfully started. There was no impact on the health and safety of the public or plant personnel.
"The NRC Resident Inspector has been notified."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
The initial loss of the south electrical bus, partial loss of off-site power, put the plant in a 24 hour limiting condition for operation (LCO) in accordance with (IAW) technical specification (TS) 3.8.1.1.E. Power was restored to the train 'B' ESF bus via an alternate offsite power source and the EDG was returned to its automatic standby condition. Currently, the plant is in a 72 hour LCO IAW TS 3.8.1.1.A.
The following information was provided by the licensee via email:
"At 0610 CST on 12/2/2023, with Unit 2 in Mode 1 at 100 percent power, the South Texas Project switchyard south electrical bus was de-energized. Emergency diesel generator (EDG) '22' automatically started in response to the loss of offsite power on the train 'B' engineered safety feature (ESF) electrical bus.
"This event is reportable under 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in the valid actuation of an emergency AC electrical power system (50.72(b)(3)(iv)(B)(8)).
"All required loads were successfully started. There was no impact on the health and safety of the public or plant personnel.
"The NRC Resident Inspector has been notified."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
The initial loss of the south electrical bus, partial loss of off-site power, put the plant in a 24 hour limiting condition for operation (LCO) in accordance with (IAW) technical specification (TS) 3.8.1.1.E. Power was restored to the train 'B' ESF bus via an alternate offsite power source and the EDG was returned to its automatic standby condition. Currently, the plant is in a 72 hour LCO IAW TS 3.8.1.1.A.
Non-Power Reactor
Event Number: 56878
Rep Org: Missouri U of Science & Tech (MIST)
Licensee: Missouri University Of Science And Technology
Region: 0
City: Rolla State: MO
County: Phelps
License #: R-79
Agreement: Y
Docket: 0500123
NRC Notified By: Ethan Taber
HQ OPS Officer: Ernest West
Licensee: Missouri University Of Science And Technology
Region: 0
City: Rolla State: MO
County: Phelps
License #: R-79
Agreement: Y
Docket: 0500123
NRC Notified By: Ethan Taber
HQ OPS Officer: Ernest West
Notification Date: 12/04/2023
Notification Time: 19:01 [ET]
Event Date: 12/01/2023
Event Time: 11:24 [CST]
Last Update Date: 12/04/2023
Notification Time: 19:01 [ET]
Event Date: 12/01/2023
Event Time: 11:24 [CST]
Last Update Date: 12/04/2023
Emergency Class: Non Emergency
10 CFR Section:
10 CFR Section:
Person (Organization):
Torres, Paulette (NRR)
Waugh, Andrew (NRR)
Torres, Paulette (NRR)
Waugh, Andrew (NRR)
SAFETY SYSTEM MALFUNCTION
The following information was provided by the licensee via phone and email:
"[The following is a report of] reactor safety system component malfunction under Missouri University of Science and Technology Reactor (MSTR) Technical Specification (TS) 6.7.2.c)iii)
"At 1124 [CST], on December 1, 2023, with the MSTR at 180 kW, a `150 Percent Full Power' scram signal was received from one safety amplifier, and the reactor scrammed automatically. Based upon other nuclear instrumentation, at no point was reactor power at, above, or near the MSTR 300-kW Limiting Safety System Setting (LSSS), nor was any transient underway that could have yielded such a situation. Power was within the 2 percent automatic control setpoint window of 180 kW, and power dropped rapidly as expected following a scram. At the time of the event, the console operator observed that the affected safety amplifier went blank, and following an approximate 0.5 second delay, returned to a normal status tracking the decay power with a scram indicator illuminated.
"At no point was the health and safety of the public or MSTR in doubt. Due to ongoing reviews and replacement component sourcing, the MSTR has not operated since the event.
"Per MSTR TS 6.7.2.c)iii), `[the license shall make a report for] a reactor safety system component malfunction that renders or could render the reactor safety system incapable of performing its intended safety function unless the malfunction or condition is discovered during maintenance tests or periods of reactor shutdowns.' Following a thorough review of the scram logic and documented failure modes and effects analysis (FMEA) provided in the system's `Operation and Maintenance Manual' (Imaging & Sensing Technology Report 021-2103, Rev. 00), in the MSTR's opinion, the safety system malfunctioned but was able to complete its safety function. The event is being reported pending further review by facility staff and discussions with Nuclear Regulatory Commission facility project management.
"This report is being made under the provisions of MSTR Technical Specification 6.7.2, requiring a report by telephone to the NRC Headquarters Operations Center no later than the following working day. Under the provisions of MSTR Technical Specification 6.7.2, a written follow-up report will be submitted to the Commission within 14 days. Additional replacement parts will need to be secured and repairs performed to restore operability."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
This event has been entered into the licensee's corrective action program.
The following information was provided by the licensee via phone and email:
"[The following is a report of] reactor safety system component malfunction under Missouri University of Science and Technology Reactor (MSTR) Technical Specification (TS) 6.7.2.c)iii)
"At 1124 [CST], on December 1, 2023, with the MSTR at 180 kW, a `150 Percent Full Power' scram signal was received from one safety amplifier, and the reactor scrammed automatically. Based upon other nuclear instrumentation, at no point was reactor power at, above, or near the MSTR 300-kW Limiting Safety System Setting (LSSS), nor was any transient underway that could have yielded such a situation. Power was within the 2 percent automatic control setpoint window of 180 kW, and power dropped rapidly as expected following a scram. At the time of the event, the console operator observed that the affected safety amplifier went blank, and following an approximate 0.5 second delay, returned to a normal status tracking the decay power with a scram indicator illuminated.
"At no point was the health and safety of the public or MSTR in doubt. Due to ongoing reviews and replacement component sourcing, the MSTR has not operated since the event.
"Per MSTR TS 6.7.2.c)iii), `[the license shall make a report for] a reactor safety system component malfunction that renders or could render the reactor safety system incapable of performing its intended safety function unless the malfunction or condition is discovered during maintenance tests or periods of reactor shutdowns.' Following a thorough review of the scram logic and documented failure modes and effects analysis (FMEA) provided in the system's `Operation and Maintenance Manual' (Imaging & Sensing Technology Report 021-2103, Rev. 00), in the MSTR's opinion, the safety system malfunctioned but was able to complete its safety function. The event is being reported pending further review by facility staff and discussions with Nuclear Regulatory Commission facility project management.
"This report is being made under the provisions of MSTR Technical Specification 6.7.2, requiring a report by telephone to the NRC Headquarters Operations Center no later than the following working day. Under the provisions of MSTR Technical Specification 6.7.2, a written follow-up report will be submitted to the Commission within 14 days. Additional replacement parts will need to be secured and repairs performed to restore operability."
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
This event has been entered into the licensee's corrective action program.