Event Notification Report for October 18, 2019
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
10/17/2019 - 10/18/2019
EVENT NUMBERS
54338
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 54338
Facility: RIVER BEND
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: DAVID DABADIE
HQ OPS Officer: HOWIE CROUCH
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: DAVID DABADIE
HQ OPS Officer: HOWIE CROUCH
Notification Date: 10/18/2019
Notification Time: 10:45 [ET]
Event Date: 10/18/2019
Event Time: 02:07 [CDT]
Last Update Date: 11/19/2019
Notification Time: 10:45 [ET]
Event Date: 10/18/2019
Event Time: 02:07 [CDT]
Last Update Date: 11/19/2019
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(A) - POT UNABLE TO SAFE SD 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
10 CFR Section:
50.72(b)(3)(v)(A) - POT UNABLE TO SAFE SD 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Person (Organization):
HEATHER GEPFORD (R4DO)
HEATHER GEPFORD (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 75 | Power Operation | 75 | Power Operation |
INADVERTENT OPENING OF MAIN TURBINE BYPASS VALVES POTENTIONALLY AFFECTED SAFE SHUTDOWN CAPABILITY
"At 0207 [CDT], the Bypass Electro-Hydraulic Control (EHC) system was secured for planned maintenance. When the Bypass EHC pumps were secured, both of the Main Turbine Bypass Valves unexpectedly opened to approximately 4.5 percent. Plant parameters indicated no impact to Turbine Control Valve position, Reactor Pressure, Turbine First Stage Pressure, or Main Steam Line flows. There were no other abnormal indications noted. With the Turbine Bypass Valves partially open, there is a potential to affect instrumentation that trips on high Turbine First Stage Pressure. Therefore, this event is being reported as a potential loss of Safety Function. At 0256, the Bypass EHC system pumps were restored and the Turbine Bypass Valves Closed.
"No radiological releases have occurred due to this event from the unit."
The licensee has notified the NRC Resident Inspector.
* * * RETRACTION FROM THONG LE TO HOWIE CROUCH AT 1019 EST ON 11/19/19 * * *
"This Event Notification was contingent on the Main Turbine Bypass Valves opening which resulted in the inoperability of Turbine First Stage Pressure monitoring instrumentation. A detailed review of system design and plant parameter trends has confirmed that the Main Turbine Bypass Valves remained closed for the duration of the event, permitting the instrumentation systems dependent on accurate Turbine First Stage Pressure to perform their respective design and licensing basis functions. Valve drift in the open direction was observed by position indication when hydraulic control pressure was removed. However, the valves were at an over-travel closed position prior to the event allowing the valves to settle at a position where an internal spring could provide closing force to the valve disc. Multiple plant parameter trends including Turbine First Stage Pressure, Reactor Pressure, Main Steam Line flows, and Main Turbine Bypass Valve discharge line temperatures indicate that the Main Turbine Bypass Valves remained closed for the duration of the event."
The licensee has notified the NRC Resident Inspector.
Notified R4DO (O'Keefe).
"At 0207 [CDT], the Bypass Electro-Hydraulic Control (EHC) system was secured for planned maintenance. When the Bypass EHC pumps were secured, both of the Main Turbine Bypass Valves unexpectedly opened to approximately 4.5 percent. Plant parameters indicated no impact to Turbine Control Valve position, Reactor Pressure, Turbine First Stage Pressure, or Main Steam Line flows. There were no other abnormal indications noted. With the Turbine Bypass Valves partially open, there is a potential to affect instrumentation that trips on high Turbine First Stage Pressure. Therefore, this event is being reported as a potential loss of Safety Function. At 0256, the Bypass EHC system pumps were restored and the Turbine Bypass Valves Closed.
"No radiological releases have occurred due to this event from the unit."
The licensee has notified the NRC Resident Inspector.
* * * RETRACTION FROM THONG LE TO HOWIE CROUCH AT 1019 EST ON 11/19/19 * * *
"This Event Notification was contingent on the Main Turbine Bypass Valves opening which resulted in the inoperability of Turbine First Stage Pressure monitoring instrumentation. A detailed review of system design and plant parameter trends has confirmed that the Main Turbine Bypass Valves remained closed for the duration of the event, permitting the instrumentation systems dependent on accurate Turbine First Stage Pressure to perform their respective design and licensing basis functions. Valve drift in the open direction was observed by position indication when hydraulic control pressure was removed. However, the valves were at an over-travel closed position prior to the event allowing the valves to settle at a position where an internal spring could provide closing force to the valve disc. Multiple plant parameter trends including Turbine First Stage Pressure, Reactor Pressure, Main Steam Line flows, and Main Turbine Bypass Valve discharge line temperatures indicate that the Main Turbine Bypass Valves remained closed for the duration of the event."
The licensee has notified the NRC Resident Inspector.
Notified R4DO (O'Keefe).