Event Notification Report for May 19, 2021
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/18/2021 - 05/19/2021
Power Reactor
Event Number: 55265
Facility: Palo Verde
Region: 4 State: AZ
Unit: [2] [] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: Jason Hill
HQ OPS Officer: Jeffrey Whited
Region: 4 State: AZ
Unit: [2] [] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: Jason Hill
HQ OPS Officer: Jeffrey Whited
Notification Date: 05/19/2021
Notification Time: 08:35 [ET]
Event Date: 05/19/2021
Event Time: 03:15 [MST]
Last Update Date: 07/02/2021
Notification Time: 08:35 [ET]
Event Date: 05/19/2021
Event Time: 03:15 [MST]
Last Update Date: 07/02/2021
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 50.72(b)(3)(v)(D) - Accident Mitigation 50.72(b)(3)(ii)(B) - Unanalyzed Condition
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS Actuation - Critical 50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation 50.72(b)(3)(v)(D) - Accident Mitigation 50.72(b)(3)(ii)(B) - Unanalyzed Condition
Person (Organization):
YOUNG, CALE (R4)
YOUNG, CALE (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | A/R | Y | 100 | Power Operation | 0 | Hot Standby |
EN Revision Imported Date: 8/2/2021
EN Revision Text: AUTOMATIC REACTOR TRIP DUE TO HIGH PRESSURIZER PRESSURE
"At 0315 MST on May 19, 2021, Unit 2 reactor automatically tripped during testing of the Plant Protection System. The Reactor Protection System actuated to trip the reactor on High Pressurizer Pressure, although no plant protection setpoints were exceeded. Main Steam Isolation Signal (MSIS), Safety Injection Actuation Signal (SIAS), and Containment Isolation Actuation Signal (CIAS) were received. No injection of water into the Reactor Coolant System occurred. Auxiliary Feedwater Actuation Signals (AFAS) 1 and 2 actuated on low Steam Generator water level post trip as designed. This event is being reported as a reactor protection system and a specified system actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A).
"Following the reactor trip, all [Control Element Assemblies] CEAs inserted fully into the core. All systems operated as expected. No emergency plan classification was required per the Emergency Plan. Safety related busses remained powered during the event from offsite power and the offsite power grid is stable. Unit 2 is stable and in Mode 3. Steam Generator heat removal is via the class 1 E powered motor driven auxiliary feedwater pump and Atmospheric Dump Valves.
"The NRC Senior Resident Inspector has been informed."
* * * UPDATE ON 5/19/21 AT 1351 EDT FROM JASON HILL TO BRIAN P. SMITH * * *
"The Unit 2 reactor tripped because of actual High Pressurizer Pressure that occurred as a result of a Main Steam Isolation Signal actuation.
"At 0337 MST, both trains of Low Pressure and High Pressure Safety Injection (LPSI and HPSI) were made inoperable when the injection valves were overridden and closed in accordance with station procedures. At 0346 MST, in accordance with station procedures, both trains of Containment Spray, LPSI, and HPSI pumps were overridden and stopped, rendering Containment Spray inoperable as well. This represents a condition that would have prevented the fulfillment of a safety function required to mitigate the consequences of an accident per 10 CFR 50.72(b)(3)(v)(D). Additionally, at the time of the Safety Injection Actuation Signal (0315 MST), both trains of Emergency Diesel Generators actuated as required and both 4160 VAC busses remained energized from off-site power.
"The NRC Senior Resident Inspector has been informed."
Notified R4DO (Young)
* * * UPDATE ON 7/02/21 AT 1943 EDT FROM YOLANDA GOOD TO JEFFREY WHITED * * *
"The inoperability of both trains of Low Pressure and High Pressure Safety Injection (LPSI and HPSI) and both trains of Containment Spray (CS) following the Unit 2 reactor trip has been determined to be an unanalyzed condition per 10 CFR 50.72(b)(3)(ii)(B). Additionally, inoperability of both trains of HPSI resulted in a reportable condition that could prevent fulfillment of its credited safety function to maintain the reactor in a safe shutdown condition per 10 CFR 50. 72(b)(3)(v)(A). The additional reporting criteria were discovered during review of the event and corresponding safety analyses.
"The NRC Senior Resident Inspector has been informed."
Notified R4DO (Werner)
EN Revision Text: AUTOMATIC REACTOR TRIP DUE TO HIGH PRESSURIZER PRESSURE
"At 0315 MST on May 19, 2021, Unit 2 reactor automatically tripped during testing of the Plant Protection System. The Reactor Protection System actuated to trip the reactor on High Pressurizer Pressure, although no plant protection setpoints were exceeded. Main Steam Isolation Signal (MSIS), Safety Injection Actuation Signal (SIAS), and Containment Isolation Actuation Signal (CIAS) were received. No injection of water into the Reactor Coolant System occurred. Auxiliary Feedwater Actuation Signals (AFAS) 1 and 2 actuated on low Steam Generator water level post trip as designed. This event is being reported as a reactor protection system and a specified system actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A).
"Following the reactor trip, all [Control Element Assemblies] CEAs inserted fully into the core. All systems operated as expected. No emergency plan classification was required per the Emergency Plan. Safety related busses remained powered during the event from offsite power and the offsite power grid is stable. Unit 2 is stable and in Mode 3. Steam Generator heat removal is via the class 1 E powered motor driven auxiliary feedwater pump and Atmospheric Dump Valves.
"The NRC Senior Resident Inspector has been informed."
* * * UPDATE ON 5/19/21 AT 1351 EDT FROM JASON HILL TO BRIAN P. SMITH * * *
"The Unit 2 reactor tripped because of actual High Pressurizer Pressure that occurred as a result of a Main Steam Isolation Signal actuation.
"At 0337 MST, both trains of Low Pressure and High Pressure Safety Injection (LPSI and HPSI) were made inoperable when the injection valves were overridden and closed in accordance with station procedures. At 0346 MST, in accordance with station procedures, both trains of Containment Spray, LPSI, and HPSI pumps were overridden and stopped, rendering Containment Spray inoperable as well. This represents a condition that would have prevented the fulfillment of a safety function required to mitigate the consequences of an accident per 10 CFR 50.72(b)(3)(v)(D). Additionally, at the time of the Safety Injection Actuation Signal (0315 MST), both trains of Emergency Diesel Generators actuated as required and both 4160 VAC busses remained energized from off-site power.
"The NRC Senior Resident Inspector has been informed."
Notified R4DO (Young)
* * * UPDATE ON 7/02/21 AT 1943 EDT FROM YOLANDA GOOD TO JEFFREY WHITED * * *
"The inoperability of both trains of Low Pressure and High Pressure Safety Injection (LPSI and HPSI) and both trains of Containment Spray (CS) following the Unit 2 reactor trip has been determined to be an unanalyzed condition per 10 CFR 50.72(b)(3)(ii)(B). Additionally, inoperability of both trains of HPSI resulted in a reportable condition that could prevent fulfillment of its credited safety function to maintain the reactor in a safe shutdown condition per 10 CFR 50. 72(b)(3)(v)(A). The additional reporting criteria were discovered during review of the event and corresponding safety analyses.
"The NRC Senior Resident Inspector has been informed."
Notified R4DO (Werner)
Non-Power Reactor
Event Number: 55266
Rep Org: Missouri University Of Science And
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: Bethany Cecere
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: Bethany Cecere
Notification Date: 05/20/2021
Notification Time: 13:13 [ET]
Event Date: 05/19/2021
Event Time: 11:00 [CDT]
Last Update Date: 05/20/2021
Notification Time: 13:13 [ET]
Event Date: 05/19/2021
Event Time: 11:00 [CDT]
Last Update Date: 05/20/2021
Emergency Class: Non Emergency
10 CFR Section:
10 CFR Section:
Person (Organization):
KENNEDY, WILLIAM (NRR PM)
Takacs, Michael (NRR ENC)
KENNEDY, WILLIAM (NRR PM)
Takacs, Michael (NRR ENC)
EN Revision Imported Date: 6/17/2021
EN Revision Text: SURVEILLANCE NOT PERFORMED IN REQUIRED TIMEFRAME
"The [Missouri University of Science and Technology Reactor] MSTR is required by Technical Specification 4.6.2(1) to perform an experimental verification of calculated airborne effluent release values every five years and when a change in licensed power occurs. An experimental verification was performed on October 24, 2019. However, in a follow-up assessment of the verification report and data, the results and analysis were determined to be non-credible. As the most recent experimental verification was completed on October 27, 2014, the MSTR does not meet the requirement of TS 4.6.2(1).
"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 (reported as EN-55266). Under the provisions of MSTR Technical Specification 6.7.2, a written follow-up report will be submitted to the Commission within 14 days. An experimental verification of gaseous effluent release will be performed as soon as practical following restoring the MSTR to an operable status, which is expected to occur no later than July 31, 2021."
The licensee will notify the NRC PM (W. Kennedy).
EN Revision Text: SURVEILLANCE NOT PERFORMED IN REQUIRED TIMEFRAME
"The [Missouri University of Science and Technology Reactor] MSTR is required by Technical Specification 4.6.2(1) to perform an experimental verification of calculated airborne effluent release values every five years and when a change in licensed power occurs. An experimental verification was performed on October 24, 2019. However, in a follow-up assessment of the verification report and data, the results and analysis were determined to be non-credible. As the most recent experimental verification was completed on October 27, 2014, the MSTR does not meet the requirement of TS 4.6.2(1).
"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 (reported as EN-55266). Under the provisions of MSTR Technical Specification 6.7.2, a written follow-up report will be submitted to the Commission within 14 days. An experimental verification of gaseous effluent release will be performed as soon as practical following restoring the MSTR to an operable status, which is expected to occur no later than July 31, 2021."
The licensee will notify the NRC PM (W. Kennedy).