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| Entered date | Event description | |
|---|---|---|
| ENS 56458 | 8 April 2023 00:59:00 | The following information was provided by the licensee via email: At 2052 EDT on April 7, 2023, during routine system preventative maintenance functional testing, the Unit 1 HPCI turbine stop valve, FV-15612, remained in the intermediate position. This failure resulted in the Unit 1 HPCI system being inoperable. This is being reported as a loss of an entire safety function condition in accordance with 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector was notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The Unit 1 HPCI inoperability places Unit 1 in a 14-day Technical Specification (TS) Limiting Condition for Operation (LCO). |
| ENS 55909 | 23 May 2022 21:01:00 | The following information was provided by the licensee via email: At 1716 hours EDT on May 23, 2022, Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed. Unit 1 reactor was being operated at approximately 100 percent (Rated Thermal Power) RTP. The Control Room received indication that both divisions of (Reactor Protection System) RPS actuated from (Reactor Pressure Vessel) RPV high pressure signals and all control rods fully inserted. The Main Turbine bypass valves opened automatically to control reactor pressure. Reactor water level lowered to -42 inches causing Level 3 and Level 2 isolations. (High Pressure Coolant Injection) HPCI (Emergency Core Cooling System) ECCS actuation occurred as designed at -38 inches and injected to the Reactor Vessel. No other ECCS system actuations occurred. (Reactor Core Isolation Cooling) RCIC automatically initiated as designed at -30 inches. The Operations crew subsequently maintained reactor water level at the normal operating band using Feedwater pumps. The reactor is currently stable in Mode 3. An investigation is in progress into the cause of the Automatic SCRAM. The NRC Senior Resident Inspector was notified. A voluntary notification to (Pennsylvania Emergency Management Agency) PEMA will be made. This event requires a 4 hour ENS notification in accordance with 10 CFR 50.72(b)(2)(iv)(A) & 10 CFR 50.72(b)(2)(iv)(B) and an 8 hour ENS notification in accordance with 10 CFR 50.72(b)(3)(iv)(A). |
| ENS 55616 | 30 November 2021 16:22:00 | At 1254 EST on November 30, 2021, Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed during Turbine Valve Cycling surveillance activities. Unit 1 reactor was being operated at approximately 80 percent rated thermal power with turbine valve cycling surveillance activities in progress. The Control Room received indication that both divisions of RPS (reactor protection system) actuated from turbine valve closure signals and all control rods fully inserted. The Main Turbine was manually tripped, and turbine bypass valves opened automatically to control reactor pressure. Reactor water level lowered to -35 inches causing Level 3 and Level 2 isolations. No ECCS (emergency core cooling systems) actuations occurred. RCIC (reactor core isolation cooling) automatically initiated as designed at -30 inches. The Operations crew subsequently maintained reactor water level at the normal operating band using Feedwater pumps and RCIC was placed in a standby lineup. The reactor is currently stable in Mode 3. An investigation is in progress into the cause of the turbine valve closure signals. The NRC Senior Resident Inspector was notified. A voluntary notification to PEMA (Pennsylvania Emergency Management Agency) will be made. This event requires a 4-hour ENS notification in accordance with 10CFR50.72(b)(2)(iv)(B) and an 8-hour ENS notification in accordance with 10CFR50.72(b)(3)(iv)(A). Unit 2 was not affected and remains at 100 percent power, Mode 1. |
| ENS 54691 | 3 May 2020 11:43:00 | At 0821 EDT on May 3, 2020, the Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed due to a trip of the Main Turbine. The Unit 1 reactor was operating at 76 percent reactor power following a ramp schedule to full power subsequent to a maintenance outage. The Control Room received indication of a Main Turbine trip with both divisions of the Reactor Protection System actuated and all control rods inserted. The Reactor Recirculation Pumps tripped on End of Cycle - Recirculation Pump Trip. Reactor water level lowered to -1 inch causing Level 3 (+13 inches) isolations. No Emergency Core Cooling System or Reactor Core Isolation Cooling actuations occurred. The operations crew subsequently maintained reactor water level at the normal operating band using Reactor Feed Water. No Steam Relief Valves opened. The reactor is currently stable in Mode 3. Investigation into the trip of the Main Turbine is in progress. The NRC Resident Inspector was notified. A voluntary notification to the Pennsylvania Emergency Management Agency and press release will occur. This event requires a 4-hour Emergency Notification System (ENS) notification in accordance with 10 CFR 50.72(b)(2)(iv)(B) and an 8-hour ENS notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72(b)(3)(iv)(B). |
| ENS 54525 | 14 February 2020 03:36:00 | At 0025 EST on February 14, 2020, Susquehanna Steam Electric Station Unit 2 reactor was manually scrammed due to rising Main Condenser backpressure caused by a loss of the Unit 2 Offgas Recombiner. Unit 2 reactor was being operated at maximum facility output, approximately 98% RTP, when at 0012 EST, Unit 2 Recombiner 0C145 Panel Trouble and 2C198 HWC Panel Trouble alarms were received along with rising Main Condenser backpressure. Initial Main Condenser backpressure was 2.6 in HgA and was rising at approximately 0.3 HgA/min. A Recirc Lim 2 was inserted to lower reactor power and condenser backpressure continued to rise following the reduction in reactor power. A manual scram was inserted at 0025 EST by placing the Mode Switch to Shutdown when condenser backpressure rose to 6 in HgA. All control rods inserted. Reactor water level lowered to -30 inches causing Level 3 (+13 inches) isolation and partial (Division 2) Level 2 (-38 inches) isolation. No ECCS actuations occurred and RCIC initiated. The Operations crew subsequently maintained reactor water level at the normal operating band using Reactor Feed Water. No steam relief valves opened. The Reactor Recirculation Pumps remained in service. The reactor is currently stable in Mode 3. Investigation into the cause of the loss of Unit 2 recombiner is underway. The NRC Senior Resident Inspector was notified. A voluntary notification to PEMA and press release will occur. |
| ENS 53310 | 3 April 2018 02:53:00 | On April 3, 2018 at 0019 (EDT), the Susquehanna control room received indication that a loss of Secondary Containment Zone 3 differential pressure had occurred. Control room operators noted the loss following completion of surveillance testing. The cause is under investigation. Zone 3 differential pressure was restored to greater than 0.25 inches WC (water column) at 0145 (EDT). Zone 3 differential pressures being less than 0.25 inches WC constitutes a loss of Secondary Containment based on not meeting requirements of SR (Surveillance Requirement) 3.6.4.1.1. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG-1022, Revision 3, Section 3.2.7, as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The NRC Resident Inspector has been notified. |