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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 49565 | 21 November 2103 03:40:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Fails Drawdown Surveillance Testing | On November 20, 2013 at 2240 (EST), secondary containment drawndown testing surveillance failed to meet acceptance criteria SR 3.6.4.1.5 due to maximum flow rate exceeding the allowable value. SSES (Susquehanna Steam Electric Station) previously entered SR 3.0.3 at 0900 on 11/15/2013 due to not meeting SR 3.6.4.1.4 and SR 3.6.4.1.5 because of an untested alignment of the 101 bay with ventilation aligned as a no zone during past performances of the drawdown testing surveillance. The surveillance being performed on 11/20/2013 was testing this previously unsurveilled alignment. Upon failure of the surveillance, secondary containment ventilation was realigned to the previously tested 818 hatch alignment. Upon restoration of secondary containment ventilation to a known operable alignment, secondary containment LCO 3.6.4.1 was cleared and operability restored. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022, Rev. 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The licensee has placed administrative controls on the 101 bay doors to prevent loss of secondary containment during the investigation to determine the reason for the surveillance test failure. The licensee has notified the NRC Resident Inspector. | Secondary containment | |
| ENS 56846 | 10 November 2023 08:14:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Scram | The following information was provided by the licensee via email: At 0118 EST, with Unit 1 in Mode 1 at 100 percent power, the reactor was manually scrammed due to degrading main condenser vacuum. The scram was not complex, with all systems responding normally post-scram. The main turbine bypass valves opened automatically to maintain reactor pressure. Operations responded and stabilized the plant. Reactor water level is being maintained via feedwater pumps. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Unit 2 is not impacted. Due to Reactor Protection System actuation while critical, this event is being reported as a four-hour and eight-hour non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). Unit 1 reactor is currently stable in mode 3. An investigation is in progress into the cause of the degrading condenser vacuum. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | Feedwater Reactor Protection System Main Condenser | |
| ENS 56532 | 22 May 2023 13:59:00 | 10 CFR 26.719, FFD Reporting requirements | FITNESS-FOR-DUTY Violation | The following information was provided by the licensee via email: A non-licensed contract supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified. | ||
| ENS 56458 | 8 April 2023 00:52:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Injection (HPCI) System Inoperable | 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 56452 | 4 April 2023 23:15:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification | The following information was provided by the licensee via email: At 1915 EDT, Susquehanna Nuclear Control Room was notified of a reportable oil release from a spare transformer outside of its secondary containment of an unknown quantity. Oil staining was observed on the ground outside of the designed containment vault stored on the grounds of Susquehanna Nuclear. The quantity and duration of the oil leak is unknown and thus poses a potential pollution risk to groundwater. Spill response measures are in-progress and as of 1500 on 4/4/2023 a field walkdown reported no visible oil outside of the containment vault. The spill event is reportable under Pennsylvania Department of Environmental Protection (PADEP) Clean Streams Law (PACSL) per PA Code 91.33 and 25 PA code 92a.41. This notification is being written to notify the US Nuclear Regulatory Commission within 4 hours of determination of a required report to another government agency per 10 CFR 50.72(b)(2)(xi). The NRC Resident Inspector has been notified. | Secondary containment | |
| ENS 56434 | 26 March 2023 20:03:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Degraded Condition - Leak Rate Limits Exceeded | The following information was provided by the licensee via email: On 03/26/2023 at 1603 EDT, while performing Appendix J local leak rate testing, it was determined that the Secondary Containment Bypass Leakage (SCBL) limit had been exceeded for Unit 2. During performance of the leak rate test, SE-259-027 for X-9B penetration, it was determined that the combined SCBL limit of 15 standard cubic feet per hour for the as-found minimum pathway was exceeded, as specified in Technical Specification, Surveillance Requirement 3.6.1.3.11. This event is being reported pursuant to 10CFR50.72(b)(3)(ii). The Resident Inspector has been notified. | Secondary containment | |
| ENS 56430 | 23 March 2023 21:36:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Emergency Diesel Generator Actuation | The following information was provided by the licensee via email: At 1736 EDT on March 23, 2023, during overcurrent testing of the '2B' (Emergency Safeguards System) ESS Bus, the work group was re-installing tested relays and inadvertently caused a '2B' ESS Bus lockout. This resulted in the '2B' ESS Bus deenergizing and a valid start signal provided to the 'B' Emergency Diesel Generator (EDG). The 'B' EDG started and functioned as designed. This is being reported as an unplanned actuation of systems that mitigate the consequences of significant events in accordance with 10 CFR 50.72(b)(3)(iv)(A). The NRC Resident Inspector has been notified. | Emergency Diesel Generator | |
| ENS 56409 | 14 March 2023 14:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Injection Inoperable | The following information was provided by the licensee via email: At 1000 EDT on March 14, 2023, during valve diagnostic testing, the high pressure core injection (HPCI) lube oil cooling water supply isolation valve did not stroke open. This failure resulted in the Unit 2 HPCI system being inoperable. This is being reported as a loss of an entire safety function condition in accordance with 10CFR50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector.
The following information was provided by the licensee via email: The purpose of this notification is to retract event notification (EN) 56409 reported on 03/14/2023. On March 09, 2023, Susquehanna Unit 2 entered a routine high pressure core injection (HPCI) maintenance outage. In support of this system outage, Technical Specification (TS) 3.5.1, Condition D was entered for an inoperable HPCI system. On March 14 as reported in EN 56409, the HPCI lube oil cooling water supply isolation valve did not electrically stroke open following engagement of manual clutch lever. Specifically, to support the maintenance evolution, electricians declutched the valve actuator to move it from the motor/electric operational mode to the manual operational mode as part of planned valve diagnostic data collection. In this testing configuration (i.e., manual operational mode), an attempt to electrically stroke the valve was made, resulting in the valve failure to stroke. Prior to this maintenance evolution, the HPCI lube oil cooling water supply isolation valve was found in the expected full-closed position with the motor/electric operational mode enabled, meaning prior to the HPCI maintenance outage, the affected valve was operating as designed and capable of performing all design functions. The described condition was therefore determined to be the result of the maintenance activity. NUREG-1022, Section 3.2.7, states: 'reports are not required when systems are declared inoperable as part of a planned evolution for maintenance or surveillance testing when done in accordance with an approved procedure and the plant's TS (unless a condition is discovered that would have resulted in the system being declared inoperable).' Following completion of investigation and repair, Susquehanna determined that, per NUREG-1022, Section 3.2.7, the event was not reportable. HPCI was declared inoperable as part of a maintenance evolution which was done in accordance with an approved procedure and the TS. The described condition was not a pre-existing condition that would have resulted in the system being declared inoperable prior to the planned maintenance activity. Notified R1DO (Schroeder) | ||
| ENS 55909 | 23 May 2022 21:16:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | Automatic Reactor Scram | 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). | Feedwater Control Rod | |
| ENS 55616 | 30 November 2021 17:54:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unit 1 Automatic Scram | 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. | Feedwater Main Turbine Control Rod | |
| ENS 55514 | 11 October 2021 17:21:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | Automatic Reactor Scram After Main Turbine Trip | At 1321 EDT on October 11, 2021, Susquehanna Steam Electric Station Unit 2 reactor automatically scrammed due to a trip of the Main Turbine. Unit 2 reactor was being operated at approximately 95 percent RTP (rated thermal power) with no evolutions in progress. The Control Room received indication of a Main Turbine trip with both divisions of RPS (Reactor Protection System) actuated and all control rods inserted. Turbine bypass valves opened automatically to control reactor pressure and subsequently failed open causing the reactor to depressurize. When reactor pressure reached approximately 560 psig, the operations crew manually closed the Main Steam Isolation Valves (MISVs) to stop the depressurization. Reactor water level lowered to -31 inches causing Level 3 (+13 inches) isolations. No (automatic) ECCS (Emergency Core Cooling System) actuations occurred. HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling) were manually initiated to control reactor water level. The Operations crew subsequently maintained reactor water level at the normal operating band using RCIC and reactor pressure was controlled with HPCI in pressure control mode and main steam line drains. The Reactor Recirculation Pumps tripped as designed on EOC-RPT (end of cycle recirculation pump trip). The reactor is currently stable in Mode 3. An investigation into the cause of the turbine trip is underway. The NRC Resident Inspector was notified. A voluntary notification to 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). | Main Steam Isolation Valve Main Turbine Reactor Recirculation Pump Main Steam Line Control Rod | |
| ENS 55370 | 21 July 2021 22:26:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor SCRAM | At 1826 EDT on July 21, 2021, Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed due to a trip of the Main Turbine. Unit 1 reactor was operating at 100 percent reactor power with no evolutions in progress. The Control Room received indication of a Main Turbine trip with both divisions of RPS (Reactor Protection System) actuated and all control rods inserted. The Reactor Recirculation Pumps tripped on EOC-RPT (end of cycle recirculation pump trip). Reactor water level lowered to +8 inches causing Level 3 (+13 inches) isolations. No ECCS (Emergency Core Cooling Systems) or RCIC (Reactor Core Isolation Cooling system) actuations occurred. The Operations crew subsequently maintained reactor water level at the normal operating band using Reactor Feed Water. The reactor is currently stable in Mode 3 with main condenser available. Investigation into the trip of the Main Turbine is in progress. The NRC Resident Inspector was notified. A voluntary notification to PEMA 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) and 10CFR50.72(b)(3)(iv)(B). | Main Turbine Reactor Recirculation Pump Main Condenser Control Rod | |
| ENS 55148 | 22 March 2021 14:05:00 | 10 CFR 50.72(b)(3)(xii), Transport of a Contaminated Person Offsite | Offsite Transport of Potentially Contaminated Person | At 1005 EDT on 3/22/2021, the control room was notified of a personal medical event in the Radiologically Controlled Area. An ambulance entered Susquehanna plant property at 1019 and exited at 1028 to transport the individual to a local hospital. Ambulance did not enter the Protected Area. The individual was considered potentially contaminated since a complete frisk could not be performed prior to transport. Following transportation to a local hospital, Radiation Protection (RP) technicians confirmed the individual and ambulance were not contaminated. This event is reportable under 10CFR50.72(b)(3)(xii). An Event of Potential Public Interest (EPPI) was made to the Pennsylvania Emergency Management Agency (PEMA) due to an emergency vehicle accessing plant property. The NRC Resident Inspector was notified. | ||
| ENS 55128 | 9 March 2021 08:13:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection Inoperable | At 0313 EST on March 9th, 2021, during performance of Unit 1 High Pressure Coolant Injection (HPCI) valve exercising, the inboard vacuum breaker isolation valve did not stroke closed as expected, but remained mid-position. The affected penetration of primary containment was isolated by closing the outboard HPCI vacuum breaker isolation valve. This results in an unplanned inoperability of the Unit 1 HPCI system. This is being reported as a loss of an entire safety function condition in accordance with 10CFR50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector. Unit 1 is in a 14-day LCO for Tech Spec 3.5.1(d), HPCI inoperability. Tech Spec 3.6.1.3(a), Containment Penetration Valve, was completed with closing the outboard HPCI vacuum breaker isolation valve. The Units are in a normal offsite power line-up. | High Pressure Coolant Injection Primary containment | |
| ENS 54691 | 3 May 2020 12:21:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Scram Due to Main Turbine Trip | 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). | Reactor Protection System Reactor Core Isolation Cooling Main Turbine Reactor Recirculation Pump Emergency Core Cooling System Control Rod | |
| ENS 54525 | 14 February 2020 05:25:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Scram Due to Rising Condenser Backpressure | 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. | Reactor Recirculation Pump Main Condenser Control Rod | |
| ENS 54148 | 4 July 2019 12:44:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Report - Licensed Supervisor Failed a Random Screening | A licensed supervisor had a confirmed positive for alcohol on a random fitness-for-duty test. The employee's access to the plant has been terminated. The licensee notified the NRC Senior Resident Inspector. | ||
| ENS 54137 | 27 June 2019 13:37:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Loss of Power Resulted in a Valid Isolation Signal | At 0937 EDT on 6/27/19, Susquehanna Unit 2 had a control power fuse fail that caused a loss of power to one of two power distribution systems of the Reactor Protection System. This loss of power resulted in a valid isolation signal and actuation of the Primary Containment Isolation System that affected multiple systems, and is reportable per 10 CFR 50.72(b)(3)(iv)(A). The situation has been resolved and the plant is currently using an alternate power source. Offsite power and the Emergency Diesel Generators are still available. The licensee notified the NRC Resident Inspector. | Reactor Protection System Emergency Diesel Generator Primary Containment Isolation System | |
| ENS 54078 | 22 May 2019 06:56:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Technical Specification Required Shutdown | On 5/22/2019, the 'A' Control Structure Chiller (Div I) tripped due to a loss of (motor control center) MCC 0B136. The 'B' Control Structure Chiller was already inoperable due to Div II (Emergency Service Water) ESW being out of service for planned maintenance. With the loss of Control Structure HVAC System the ability to maintain temperatures in various spaces including relay rooms, Control Room Floor Cooling and Emergency Switchgear rooms was lost. The 'B' Control Structure Chiller was restarted at 0251 EDT and cooling was reestablished to the required areas, however the 'B' chiller is not considered operable at this time. Units 1 and 2 entered (Technical Specification) TS 3.0.3 at 0256 EDT and a controlled shutdown of both units commenced, Unit 2 at 0340 EDT and Unit 1 0350 EDT. This constitutes a TS required shutdown and requires a 4 hour (Emergency Notification System) ENS notification in accordance with 10 CFR 50.72(b)(2)(i). The failure also requires an 8 hour ENS notification in accordance with 10 CFR 50.72(b)(3)(v) due to the loss of a safety function. The licensee needs to restore the 'B' loop of ESW to exit the Limiting Condition of Operation (LCO). The licensee is currently performing a flow surveillance, once complete and assuming the data is acceptable, the licensee will be able to exit the LCO. The units are in a normal electrical lineup. The licensee will be notifying the state of Pennsylvania FEMA Operations Center. The licensee has notified the NRC Resident Inspector.
On 5/22/2019 at 0601 EDT Susquehanna Steam Electric Station reported a shutdown had been commenced at 0340 EDT for Unit 2 and 0350 EDT for Unit 1 due to inoperability of both control structure chillers. Power has been restored to MCC 0B136, and at 0901 EDT the 'A' control structure chiller was declared operable and LCO 3.0.3 was exited. Power reduction for both units was halted at 0901 EDT and preparations for power restoration initiated. As of 1255 EDT on 5/22/2019, Unit 1 power is 94% and Unit 2 power is 92%. Notified the R1DO (Arner). | HVAC | |
| ENS 54055 | 9 May 2019 13:16:00 | 10 CFR 26.719, FFD Reporting requirements | Employee Supervisor Tested Positive on a Random Fitness-For-Duty Test | A non-licensed employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the site has been terminated. The NRC Resident Inspector has been informed. | ||
| ENS 54103 | 18 April 2019 05:10:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification Due to Invalid Specified System Actuation | This 60-day telephone notification is being made in accordance with the reporting requirements specified by 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a general containment isolation signal affecting multiple Main Steam Isolation Valves (MSIVs). On April 18, 2019 at approximately 0110 EDT, during performance of an ASME reactor vessel leak check, all four inboard MSIVs closed as a result of actuation of the Main Steam Line (MSL) high flow instrumentation. The high flow signal was spurious on the 'D' channel with no flow in the MSLs. Since an actual high flow condition did not exist at the time of the actuation, the actuation was considered invalid. The MSIVs functioned as designed on actuation of the MSL high flow instrumentation. All outboard MSIVs were closed at the time of the actuation in accordance with the vessel leak check procedure. The NRC Resident Inspector has been notified. | Main Steam Isolation Valve Main Steam Line | |
| ENS 53352 | 20 April 2018 04:00:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Policy Violation | A non-licensed supervisory contract worker was found in violation of the Fitness for Duty Program. The individual's access to the plant has been terminated. The licensee notified the NRC Resident Inspector. | ||
| ENS 53310 | 3 April 2018 04:19:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Following Surveillance Testing | 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. | Secondary containment | |
| ENS 53256 | 12 March 2018 10:53:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty - Non-Licensed Supervisor Tested Positive for Alcohol | A non-licensed supervisor tested positive for alcohol during pre-access screening. The individual's access to the plant was denied. The NRC Resident Inspector has been notified. | ||
| ENS 53202 | 12 February 2018 03:03:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Differential Pressure Out of Specification | On February 11, 2018 at 2203 (EST), the Susquehanna Control Room received indication that a loss of Secondary Containment Zone 2 differential pressure (DP) had occurred. Control Room operators noted a differential pressure of <.25" WC (inches Water Column) for several seconds. System DP was restored to normal in 1 minute. The cause of the pressure swings is under investigation. Zone 2 differential pressures being less than 0.25" WC constitutes a loss of Secondary Containment based on not meeting requirements of SR 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 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee notified the NRC Resident Inspector. | Secondary containment | |
| ENS 53098 | 30 November 2017 15:26:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Differential Pressure Briefly Indicated Outside of Tech Spec Limit | On November 30, 2017 at 1026 EST, the Susquehanna Control Room received indication that a loss of Secondary Containment Zone 2 differential pressure had occurred. Control Room operators noted a differential pressure of 0.0 inch WC (water column) for several seconds, followed by a high DP of 0.5 inch WC. System DP was restored to normal in 3 minutes. The cause of the pressure swings is under investigation. Zone 2 differential pressures being less than 0.25 inch WC constitutes a loss of Secondary Containment based on not meeting requirements of SR 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, Rev. 3, Section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee notified the NRC Resident Inspector. | Secondary containment | 05000387/LER-2017-007 |
| ENS 53003 | 6 October 2017 23:45:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Loss of Control Room Habitability Envelope | On October 6, 2017 at 1945 EDT, a loss of Control Room Habitability Envelope (CRE) was declared due to failing to meet the requirements of SR 3.7.3.4 during 72 month surveillance testing. Measured in-leakage exceeded the SR acceptance value. The CRE is required to be maintained such that occupants can control the reactor safely under normal conditions and maintain it in a safe condition following a radiological event, hazardous chemical release, or a smoke challenge. The station remains in compliance with Technical Specification required action statements. This event is being reported under 10 CFR 50.72(b)(3)(v)(D) and per the guidance of NUREG 1022, Rev. 3, Section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Control Room Habitability Envelope. The licensee notified the NRC Resident Inspector. | 05000387/LER-2017-006 | |
| ENS 52973 | 16 September 2017 17:30:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Differential Pressure | On September 16th, 2017 at 1330 hrs. (EDT), a loss of secondary containment differential pressure (D/P) occurred due to an equipment failure. This caused a reduction in Reactor Building Zone 2 (Unit 2) D/P to less than the required 0.25 inches WC per SR (Surveillance Requirement) 3.6.4.1.1. 2V206B, Reactor Building Zone 2 Equipment Compartment Exhaust Fan, was manually started and Reactor Building Zone 2 D/P was restored to greater than 0.25 inches WC by 1333 hrs. Reactor Building Zone 1 (Unit 1) and Zone 3 (Units 1&2) ventilation remained in service and stable. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022, Rev. 3, section 3.2.7, as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee has notified the NRC Resident Inspector. | Secondary containment | 05000388/LER-2017-009 |
| ENS 52892 | 9 August 2017 00:44:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Differential Pressure | On August 8th, 2017 at 2044 hrs. (EDT) a loss of secondary containment differential pressure (D/P) occurred due to an apparent equipment failure. This caused a reduction in Reactor Building Zone II (Unit 2) D/P to less than the required 0.25 inch WC (water column) per SR (Surveillance Requirement) 3.6.4.1.1. Reactor Building Zone II Exhaust Fans were manually swapped and Reactor Building Zone II D/P was restored to greater than 0.25 inch WC by 2112 hrs. Reactor Building Zone 1 (Unit 1) and Zone 3 (Units 1&2) ventilation remained in service and stable. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee notified the NRC Resident Inspector. | Secondary containment | |
| ENS 52844 | 10 July 2017 06:50:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Due to Failure of Non-Safety Related Discharge Damper | On July 10th, 2017 at 0250 hrs. (EDT) a loss of secondary containment differential pressure (D/P) occurred due to failure of a non-safety related discharge damper associated with 2V205B Reactor Building Zone II Exhaust Fan. This caused a reduction in Reactor Building Zone II (Unit 2) D/P to less than the required 0.25 inches WC (Water Column). 2V205A Reactor Building Zone II Exhaust Fan was manually started and Reactor Building Zone II D/P was restored to greater than 0.25 inches WC by 0301 hrs. Reactor Building Zone 1 (Unit 1) and Zone 3 (Units 1&2) ventilation remained in service and stable. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022, Rev. 3, section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee notified the NRC Resident Inspector. | Secondary containment | 05000388/LER-2017-006 |
| ENS 52826 | 24 June 2017 14:28:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment | On June 24, 2017 at 1028 (EDT), a loss of secondary containment occurred due to trip of 2V217A Zone III Filtered Exhaust Fan causing a reduction in D/P (differential pressure) to less than the required 0.25 WC (water column). 2V217B Zone III Filtered Exhaust Fan started on low flow in AUTO as designed and secondary containment D/P was restored to greater than 0.25 WC by 1029 hours. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022, Rev. 3, section 3.2.7 as a loss of a safety function. There is no redundant Susquehanna secondary containment system. The licensee notified the NRC Resident Inspector. | Secondary containment | 05000388/LER-2017-005 |
| ENS 52797 | 9 June 2017 09:09:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Exhaust Fan Breaker Failure Causing Low Secondary Containment Differential Pressure | On June 9, 2017 at 0509 (EDT), Secondary Containment Zone 3 (Unit 1 and 2 Reactor Building) differential pressure lowered to 0 (inches) WG (water gauge) during a routine restoration due to equipment failure. One of the two Unit 1 Zone 3 exhaust fan breakers experienced a failure that during procedural restoration caused Secondary Containment Zone 3 to experience a positive differential pressure. Required differential pressure per SR 3.6.4.1.1 could not be maintained. Zone 3 differential pressure was recovered to (greater than) 0.25 (inches) WG following restart of Unit 2 Zone 3 Secondary Containment fans. All other Zones of Secondary Containment were unaffected by this event. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022 Rev 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. | Secondary containment | |
| ENS 52795 | 8 June 2017 19:27:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | Automatic Reactor Scram After Main Turbine Control Logic Loss of Power | At 1527 hrs (EDT) on June 8, 2017, Susquehanna Steam Electric Station Unit 1 reactor automatically scrammed due to a loss of Main Turbine Electro-Hydraulic Control (EHC) logic power causing a High Flux Reactor Power RPS (Reactor Protection System) trip. All control rods (fully) inserted and both reactor recirculation pumps tripped due to reaching reactor water level 2. Reactor water level lowered to -49 inches causing Level 3 (+13 inches) and Level 2 (-38 inches) isolations. HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling) automatically initiated and were overridden by control room operators after RPV (Reactor Pressure Vessel) water level was restored to the normal band with feedwater. HPCI and RCIC injected to the Reactor Coolant System during reactor level stabilization. All isolations and initiations occurred as expected. No main steam relief valves opened. Pressure was controlled via main turbine bypass valve operation. All safety systems operated as expected. Secondary Containment Zone 1, 2, and 3 differential pressure lowered to 0 inch WG (Water Gauge) due to a trip of the Reactor Building Ventilation system that resulted from Unit 1 Level 2 isolation. Differential pressure was restored to Zones 1, 2, and 3 by the initiation of Standby Gas Treatment System on the Unit 1 Level 2 initiation. Unit 1 reactor is currently stable in Mode 3. Investigation into the loss of Main Turbine EHC logic power is underway. The NRC Resident Inspector has been notified. A voluntary notification to PEMA and press release will occur. The suspected cause of the loss of power to the EHC logic circuit is ongoing maintenance on the system. | Reactor Coolant System Feedwater Secondary containment Main Turbine Reactor Recirculation Pump Reactor Building Ventilation Standby Gas Treatment System Control Rod Main Steam | 05000387/LER-2017-005 |
| ENS 52658 | 3 April 2017 14:45:00 | 10 CFR 20.1906(d)(2) 10 CFR 20.1906(d)(1) | Exclusive Use Transport Vehicle Exceeded Contact Dose Rates | This is being reported under 10CFR20.1906(d)(1,2). At 1045 hours (EDT), the SSES (Susquehanna Steam Electric Station) Radwaste shipper was notified by the RP (Radiation Protection) shipping technician performing a receipt survey of an open transport vehicle shipped exclusive use carrying an empty radwaste liner exceeded the 10CFR71.47(b)(1) vehicle contact dose rates of 200 mR/hr. Per NDAP-QA-0720 (Nuclear Department Administrative Procedure) Attachment E, contaminated /radioactive shipments this is a 1 hour notification for exceeding the radiological receipt survey requirements of 200 mR/hr at any point on the outer surface of the vehicle. The vehicle was from Energy Solutions. The licensee will be using the vehicle to transport radwaste from the facility. The licensee has notified the Pennsylvania Emergency Management Agency and the NRC Resident Inspector. | ||
| ENS 52772 | 3 April 2017 01:27:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of Invalid Specified System Actuation | This 60-day telephone notification is being made in accordance with the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting multiple Main Steam Isolation Valves (MSIVs). On April 2, 2017 at approximately 2127 Eastern Daylight Time, during performance of a reactor vessel leak check, all four inboard MSIVs closed as a result of actuation of the Main Steam Line (MSL) high flow instrumentation. The high flow signal was spurious on two channels with no flow in the MSLs. Since an actual high flow condition did not exist at the time of the actuation, the actuation was considered invalid. The MSIVs functioned as designed on actuation of the MSL high flow instrumentation. All outboard MSIVs were closed at the time of the actuation. The NRC Resident Inspector has been notified. | Main Steam Isolation Valve Main Steam Line | |
| ENS 52599 | 8 March 2017 07:39:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Due to Containment Fan Trip | On March 08, 2017 at 0239 hours (EST), Secondary Containment Zone 3 (Unit 1 and 2 Reactor Building) differential pressure lowered to 0 (inches) WG due to a trip of the running Zone 3 Secondary Containment fans. The fan trip was caused by a human performance error during a Unit 2 outage related activity. Required differential pressure per SR 3.6.4.1.1 could not be maintained. Zone 3 differential pressure recovered to (greater than) 0.25 (inches) WG at 0255 hours after restart of Zone 3 Secondary Containment fans. All other Zones of Secondary Containment were unaffected by this event. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022 Rev. 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The licensee informed the NRC Resident Inspector. | Secondary containment | |
| ENS 52552 | 15 February 2017 18:37:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Differential Pressure | On February 15, 2017 at 1337 (EST), Secondary Containment Zone 1 (Unit 1 Reactor Building) differential pressure lowered to 0 inches WG (Water Gauge) due to a trip of the running Unit 1 B Filtered Exhaust Fan. Required differential pressure per SR (Surveillance Requirement) 3.6.4.1.1 could not be maintained. Zone 1 differential pressure recovered to greater than 0.25 inches WG less than one minute later after start of the standby Zone 1 Filtered Exhaust Fan. Zone 2 (Unit 2 Reactor Building) and Zone 3 (Common Areas of Unit 1&2 Reactor Buildings) ventilation remained in service and stable. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG-1022, Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. Post-maintenance testing was underway when the fan tripped. While the investigation is on-going to determine the cause, the licensee does not believe the maintenance or testing caused the fan to trip The licensee has notified the NRC Resident Inspector.
The Unit 1 B Filtered Exhaust Fan trip that resulted in loss of secondary containment differential pressure occurred during post maintenance testing (PMT). The PMT was being performed following replacement of a flow controller associated with the Unit 1 B Filtered Exhaust Fan. In support of the PMT, Technical Specification (TS) 3.6.4.1 Condition A had been entered and was in effect at the time of the fan trip. The maintenance and the associated PMT were performed in accordance with approved work instructions/procedure. Subsequent to the initial report, Susquehanna troubleshooting determined that the fan trip was the result of an internal leak in the newly installed controller that prevented the new controller from functioning properly. The condition was therefore determined to have been the result of the completed maintenance. NUREG-1022, Section 3.2.7, includes the following guidance: '...reports are not required when systems are declared inoperable as part of a planned evolution for maintenance or surveillance testing when done in accordance with an approved procedure and the plant's TS (unless a condition is discovered that would have resulted in the system being declared inoperable).' Following completion of the troubleshooting, Susquehanna determined that, per NUREG-1022, Section 3.2.7, the event was not reportable. Secondary Containment was declared inoperable as a part of a planned evolution for maintenance which was done in accordance with an approved procedure and the Susquehanna TS. The discovered condition was not a pre-existing condition that would have resulted in the system being declared inoperable prior to the planned maintenance activity. The licensee notified the NRC Resident Inspector. Notified R1DO (Jackson). | Secondary containment | |
| ENS 52369 | 16 November 2016 15:45:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Failure of Unit 2 B Engineered Safeguards System Bus Sync Selector Switch | On November 16, 2016 at 1045 (EST), Unit 2 B ESS (Engineered Safeguards System) Bus Sync Selector switch failed and was unable to be switched out of the ON position. The failure rendered all other sync selector switches associated with Emergency Diesel Generators and Off-Site supplies to the ESS buses unable to fulfill their intended function of allowing manual transfer between power supplies to the ESS buses. This resulted in the inability of Unit 1 and Unit 2 to comply with SR (Surveillance Requirements) 3.8.1.8 and 3.8.1.16 thus requiring declaration of Operating AC Sources inoperable. This condition could have prevented the fulfillment of the safety function of systems required to maintain the reactor in a safe shutdown condition, remove residual heat, control the release of radioactive material, and mitigate the consequences of an accident. Subsequent actions were taken in accordance with station procedures to remove fuses for the affected sync circuit, restoring the manual transfer function to all but the Unit 2 B ESS bus. One Emergency Diesel and one offsite source remain inoperable with the fuses removed. At no time were any ESS buses disconnected from offsite power. All ESS buses remained capable of being automatically energized from their respective emergency diesel in an emergency. The licensee has notified the NRC Resident Inspector. | Emergency Diesel Generator | |
| ENS 52266 | 27 September 2016 20:44:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Leakage Exceeding Requirements | On September 27, 2016 at 1644 (EDT), damaged ductwork was identified in the secondary containment boundary associated with reactor building zone 3 (Units 1 and 2) recirculation plenum. The size of the hole in the secondary containment boundary was determined to be 22.5 square inches. Due to exceeding allowable total leakage in the current secondary containment isolation configuration, a violation of SR 3.6.4.1.5 (occurred). Action to establish a tested configuration with sufficient inleakage margin to restore compliance with SR 3.6.4.1.5 was completed September 27, 2016 at 2115 hrs. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022, Rev 3, Section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The licensee notified the NRC Resident Inspector.
Following the 8 hour 10 CFR 50.72 notification made on September 27, 2016 (EN 52266), further engineering analysis determined that the as-found tear in the Zone 3 ductwork did not impact the ability of Secondary Containment to perform its safety function and that Secondary Containment was not inoperable as a result of the condition. To support the determination, a drawdown test was conducted in a limiting configuration (i.e. least inleakage margin). No substantial change in drawdown testing results were observed over the last three tests. These tests spanned over seven years. Additionally, repairs were promptly made to the affected area. As a result, this event notification is being retracted as it is not reportable pursuant to 10 CFR 50.72(b)(3)(v)(C). The licensee notified the NRC Resident Inspector. Notified the R1DO (Dwyer). | Secondary containment | |
| ENS 52255 | 22 September 2016 07:20:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Differential Pressure | On September 22, 2016, at 0320 (EDT), Secondary Containment Zone 2 (Unit 2 Reactor Building) differential pressure lowered to 0.15 (inch) WG due to a stuck non-safety related exhaust damper on the in service Zone 2 exhaust fan. Required differential pressure per SR 3.6.4.1.1 could not be maintained. Zone 2 differential pressure recovered to greater than 0.25 (inch) WG on September 22, 2016 at 0342 (EDT) by starting the standby Zone 2 exhaust fan. Zone 1 (Unit 1 Reactor Building) and Zone 3 (Unit 1&2 Reactor Buildings) ventilation remained in service and stable. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The Licensee notified the NRC Resident Inspector. | Secondary containment | 05000388/LER-2016-006 |
| ENS 51987 | 8 June 2016 06:26:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Discovery of Unisolable Reactor Pressure Boundary Leakage | Susquehanna Unit 1 identified RPV (reactor pressure vessel) pressure boundary leakage from (local power range monitor) LPRM 24-09 housing above the flange during an under vessel leak inspection on 06/08/2016 at 0226 EDT. The leakage point is a through wall indication on the ASME Class 1 LPRM stub tube. The leakage is not isolable from the reactor vessel. The reactor was in Mode 4 at the time of discovery. This event is being reported as a degraded condition pursuant to 10CFR50.72(b)(3)(ii)(A). A repair plan is being formulated. The licensee has notified the NRC Resident Inspector. | ||
| ENS 51983 | 6 June 2016 09:56:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Isolable Leakage Identified from Seal Water Line Weld Inside Rcs Pressure Boundary | Susquehanna Unit 1 commenced a manual shutdown on 06/05/2016 for a maintenance outage. At 2202 hours (EDT) on 06/05/2016, operators began reducing power in accordance with plant procedures. At 0352 hours on 06/06/2016, the Main Turbine was tripped with reactor power at approximately 15%. The Mode switch was taken to 'STARTUP/HOT STANDBY' (Mode 2) at 0515 hours on 06/06/2016. Manual insertion of control rods was paused as scheduled for entry into the drywell for inspections. There were no ESF actuations. At 0556, the licensee identified leakage from a weld on seal water line piping connected to the 1B reactor recirculation pump seal area. The location is within the reactor recirculation loop isolation valves, therefore is isolable from the reactor vessel. The piping is ASME Class 2 and is reactor coolant pressure boundary. The reactor was in Mode 2 at the time of discovery. This event is being reported as a plant shutdown required by technical specifications pursuant to 10CFR50.72(b)(2)(i) and degraded condition pursuant to 10CFR50.72(b)(3)(ii)(A). Activities are continuing to achieve cold shutdown. The licensee informed the Commonwealth of Pennsylvania and the NRC Resident Inspector. | Main Turbine Reactor Recirculation Pump Control Rod | |
| ENS 51925 | 13 May 2016 05:10:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Manual Reactor Scram Due After Loss of an Essential Motor Control Center | At approximately 0110 hours (EDT) on May 13, 2016, Susquehanna Steam Electric Station Unit Two reactor was manually scrammed by plant operators due to a sustained loss of AC power to essential plant loads. Power to MCC 2B246 was lost at 2355 on May 12, 2016, resulting in a loss of Drywell cooling. Drywell pressure increased to 1.3 psig when operators placed the mode switch to the shutdown position to manually SCRAM the reactor. All rods inserted as expected. Reactor water level lowered to -27 inches and was immediately restored by normal feedwater level control. Level 3 (+13 inch) PCIS isolations occurred, along with an initiation of the RCIC system (-30 inches). Once adequate level was verified, RCIC was overridden. Pressure was controlled with turbine bypass valves, and subsequently main steam line drains. All safety systems functioned as expected. The power loss also tripped Reactor Building HVAC, causing a loss of secondary containment differential pressure resulting in a loss of safety function. Due to the loss of drywell cooling, high drywell pressure actuations and a second reactor SCRAM signal, this signal was automatic, occurred at 0314 hours. HPCI (which automatically initiated on high drywell pressure) was subsequently overridden and declared inoperable, resulting in a loss of safety function. (HPCI did not inject into the vessel). The reactor is currently stable in Mode 3. Initial reports from the field indicate a phase to phase fault on the MCC 2B246 bus bars. The licensee has notified the NRC Resident Inspector and will be issuing a press release. | Feedwater Secondary containment HVAC Main Steam Line | |
| ENS 51872 | 20 April 2016 01:59:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Inoperable Secondary Containment | On April 19th, 2016 at 2159 (EDT), Secondary Containment became inoperable due to failure to meet Surveillance Requirement (SR 3.6.4.1.1) on Unit 1 and Unit 2. The inoperability was caused when Reactor Building differential pressure was discovered to be less than Technical Specification requirements (-0.25 inches of water gauge). Secondary Containment was restored April 19, 2016 at 2222 by adjusting intake louvers in accordance with off normal operating procedure ON-RBHVAC-201. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee notified the NRC Resident Inspector. | Secondary containment | 05000388/LER-2016-003 |
| ENS 51851 | 6 April 2016 17:37:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Reactor Building Airlock Doors Opened Simultaneously | On April 6th, 2016 at 1337 (EDT) and 1343 (EDT) Secondary Containment became inoperable due to failure to meet a Surveillance Requirement (SR 3.6.4.1.3) on Unit 1 and Unit 2. The inoperability was caused when two separate sets of Reactor Building airlock doors were sequentially opened during a medical emergency to transport an individual. Each set of airlock doors was opened momentarily to allow passage. Secondary Containment was restored April 6, 2016 at 1344 (EDT) when the transport evolution was complete. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022 Rev 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. | Secondary containment | 05000387/LER-2016-010 |
| ENS 51838 | 31 March 2016 10:03:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Valid Isolation Signal Due to a Human Performance Error | On March 31, 2016 at 0603 (EDT), with Susquehanna Unit 1 in its 19th Refueling and Inspection Outage, Unit 1 received a valid isolation signal. Preliminary investigation indicates the isolation signal was the result of a human performance error. The systems affected by the isolation signal responded as designed for the current shutdown plant conditions. This isolation of multiple primary containment isolation systems is being reported under 10CFR50.72(b)(3)(iv)(A) and per the guidance of NUREG 1022, Rev. 3, section 3.2.6 as a system actuation. The licensee notified the NRC Resident Inspector. | Primary Containment Isolation System | |
| ENS 51830 | 30 March 2016 02:56:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Secondary Containment Differential Pressure | On March 29, 2016 at 2256 (EDT), Secondary Containment Zone 2 (Unit 2 Reactor Building) differential pressure lowered to 0.0 (inches) WG (water gauge) due to a failed closed discharge damper on the in service Zone 2 exhaust fan. Required differential pressure per SR 3.6.4.1.1 could not be maintained. Zone 2 ventilation was restored by starting the standby Zone 2 exhaust fan. Zone 2 differential pressure recovered to (greater than) 0.25 (inches) WG at 2321 hours. Zone 3 (Unit 1&2 Reactor Buildings) ventilation remained in service and stable. Zone 1(Unit 1 Reactor Building) ventilation remained in service however it is not required in this mode of Operation. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The licensee has notified the NRC Resident Inspector. | Secondary containment | 05000387/LER-2016-012 |
| ENS 51777 | 8 March 2016 07:32:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Differential Pressure Outside Specification | On March 8, 2016 at 0232 hours (EST), Secondary Containment Zone 3 (Unit 1&2 Reactor Building) differential pressure lowered to 0.16 inches water gauge when securing Unit 1 Zone 3 HVAC for planned maintenance. Required differential pressure per SR 3.6.4.1.1 could not be maintained in the intended alignment. Zone 3 ventilation was restored to the original alignment and Zone 3 differential pressure recovered to greater than 0.25 inches water gauge at 0335 hours. Zone I (Unit 1 Reactor Building) and Zone II (Unit 2 Reactor Building) ventilation remained in service and stable. Station engineering and maintenance are investigating the Zone 3 HVAC system to determine the cause. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022, Rev. 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. | Secondary containment HVAC | |
| ENS 51764 | 2 March 2016 18:30:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable | On March 2, 2016 at 1330 hrs. (EST), Secondary Containment became inoperable due to failure to meet a Surveillance Requirement (SR 3.6.4.1.3). The inoperability was caused when Unit 2 Reactor Building Airlock doors were inadvertently opened simultaneously. Secondary Containment was restored March 2, 2016 at 1331 hrs. when the doors were closed. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022, Rev. 3, section 3.2.7, as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee has notified the NRC Resident Inspector. | Secondary containment | |
| ENS 51750 | 22 February 2016 18:45:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Unit 1 Secondary Containment Inoperable When Personnel Opened Both Access Doors Simultaneously | On February 22, 2016 at 1345 (EST). Secondary Containment became inoperable due to failure to meet a Surveillance Requirement (SR 3.6.4.1.3) on Unit 1. The inoperability was caused when Unit 1 Reactor Building Airlock doors were inadvertently opened simultaneously. Secondary Containment was restored February 22, 2016 at 1346 when the doors were closed. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022, Rev. 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee informed the NRC Resident Inspector. | Secondary containment | 05000387/LER-2016-002 05000387/LER-2016-001 |