Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56471 | 17 April 2023 07:46:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Single Train of LOW Pressure Core Spray Inoperable | The following information was provided by the licensee via email: At 0246 CDT on April 17, 2023, it was discovered that the single train low pressure core spray system was inoperable. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). All other emergency core cooling systems remained operable during this time period. 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: LaSalle Unit 1 is in a 7 day limiting condition for operation. | Core Spray Emergency Core Cooling System | |
| ENS 56203 | 4 November 2022 05:06:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Both Trains of Control Room Area Ventilation Air Conditioning System Inoperable | The following information was provided by the licensee via email: At 0006 CDT on 11/04/2022, it was discovered that both trains of control room area ventilation air conditioning systems were simultaneously inoperable. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function. Therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). 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: With both trains of control room area ventilation air conditioning systems inoperable, the plant entered a 72 hour limiting condition for operation (LCO). One train had been restored at the time of report which extends the LCO to 30 days. | ||
| ENS 55908 | 23 May 2022 17:56:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Both Trains of Control Room Area Ventilation Air Conditioning System Inoperable | The following information was provided by the licensee via fax: At 1256 CST on 05/23/2022, it was discovered both trains of Control Room Area Ventilation Air Conditioning Systems were simultaneously INOPERABLE. Due to this INOPERABILITY, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | ||
| ENS 55905 | 20 May 2022 14:05:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Both Trains of Control Room Area Filtration System and Area Ventilation Air Conditioning System Inoperable | The following information was provided by the licensee via email: At 0905 CST on 05/20/2022, it was discovered both trains of Control Room Area Filtration and Area Ventilation Air Conditioning Systems were simultaneously INOPERABLE. Due to this INOPERABILITY, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | ||
| ENS 55046 | 23 December 2020 12:53:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Spray Inoperable | At 0653 CST on 12/23/20, it was discovered the single train of high pressure core spray was inoperable. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). All other emergency core cooling systems were operable during this time. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The high pressure core spray is inoperable because the water lake pump tripped. This inoperability puts the licensee in a 14-day limiting condition for operability. | High Pressure Core Spray Emergency Core Cooling System | |
| ENS 54693 | 4 May 2020 21:40:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Diesel Generator Cooling Water System Declared Inoperable | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to mitigate the Consequences of an Accident. A through wall leak was found on piping connected to the Division 3 Diesel Generator (DG) Cooling Water Strainer. This condition has been evaluated and the Division 3 DG Cooling Water System has been declared inoperable. The Division 3 DG Cooling Water System is a support system for the Division 3 Emergency DG and the High Pressure Core Spray System (HPCS). The NRC Resident Inspector has been notified.
This update retracts Event Notification #54693, which reported a condition that could have potentially prevented fulfillment of a safety function needed to mitigate the consequences of an accident. An evaluation of the flaw on the piping connected to the Unit 2 Division 3 Diesel Generator (DG) Cooling Water strainer concluded that the system would have remained operable. The High Pressure Core Spray system, supported by the operable DG Cooling Water system, remained operable and capable of performing its safety function. The NRC Resident Inspector has been notified. Notified R3DO (Stone). | High Pressure Core Spray | |
| ENS 53219 | 17 February 2018 08:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Damaged Bus Bar Identified Potentially Affecting High Pressure Core Spray | This report is being made in accordance with 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. While troubleshooting an issue with the Unit 1B Diesel Generator Oil Circulating pump, damage of a bus bar was identified at the breaker that supplies the Unit 1B Diesel Generator Auxiliaries. One of the loads fed from this breaker is the Division 3 DC Battery Charger. It has been determined that the degradation of the bus bar may have prevented the Division 3 DC Battery Charger from performing its function which could have prevented the High Pressure Core Spray System (HPCS) from performing its design safety function. Since HPCS is a single train safety system, it has been determined that this failure could potentially affect the safety function of this system, and is reportable as an 8 hour notification. The NRC Resident Inspector has been notified. | High Pressure Core Spray | |
| ENS 53213 | 15 February 2018 17:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Notification of Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missiles | On February 15, 2018, during evaluation of protection for Technical Specifications (TS) equipment from the damaging effects of tornado generated missiles, LaSalle Station identified a non-conforming condition in the plant design such that specific TS equipment is considered to not be adequately protected from tornado generated missiles. Tornado generated missiles could strike the components supporting the operation of Control Room (VC) and Auxiliary Electric Room (VE) ventilation. This could result in inoperable VC/VE systems, which provide a protected environment for occupants to control the unit following an uncontrolled release of radioactivity, hazardous chemicals, or smoke if a tornado were to occur. This condition is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B) as a condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety and 10 CFR 50.72(b)(3)(v)(D) as a condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. This condition is being addressed in accordance with NRC enforcement guidance provided in Enforcement Guidance Memorandum (EGM) 15-002, Revision 1, 'Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance,' and DSS-ISG-2016-01, Revision 1, 'Clarification of Licensee Actions in Receipt of Enforcement Discretion' per Enforcement Guidance Memorandum EGM 15-002, 'Enforcement Discretion for Tornado Generated Missile Protection Noncompliance.' Compensatory measures have been implemented in accordance with these documents. The NRC Resident Inspector has been informed of this notification. | ||
| ENS 52821 | 23 June 2017 01:43:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Low Pressure Core Spray Declared Inoperable Due to Loss of Cooling | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. The Unit 1 Low Pressure Core Spray (LPCS) Pump Injection System was declared inoperable at 2043 (CDT) due to a loss of corner room area cooling and loss of motor cooling. The common diesel generator cooling water pump received an auto trip signal while being secured. The LPCS pump remained in standby during the event. This condition prevents LPCS, a single train safety system, from performing its design function. This is a reportable condition as an 8 hour ENS notification. The required action of Technical Specifications (TS) 3.5.1, 'ECCS - Operating,' was entered on June 22, 2017 at 2043 CDT when the condition was identified and the LPCS system was determined to be inoperable. Investigation into the cause of the condition is in progress. The Low Pressure Core Spray (LPCS) Pump Injection System was declared operable, and the TS LCO was exited at 2112 CDT.
Update to previous ENS notification at 0100 EDT on 6/23/17. The last statement was revised to say the Low Pressure Core Spray System remains Inoperable. The Low Pressure Core Spray (LPCS) Injection System remains inoperable. The licensee notified the NRC Resident Inspector. Notified R3DO (Pelke). | Core Spray | |
| ENS 52761 | 17 May 2017 14:08:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Low Pressure Core Spray Pump Inoperable Due to Minimum Flow Valve Closure | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. The Low Pressure Core Spray (LPCS) Pump Injection HI Flow alarm was received at 09:08 CDT on May 17, 2017, at which point the minimum flow valve was observed to go closed. The LPCS pump remained in standby during the event. To prevent damage if the pump were to auto start, the control switch for the LPCS pump was placed in pull to lock. This condition prevents LPCS, a single train safety system, from performing its design function. This is a reportable condition as an 8 hour ENS notification. The required action of Technical Specifications (TS) 3.5.1, 'ECCS - Operating,' was entered on May 17, 2017 at 09:08 CDT when the condition was identified and the LPCS system was determined to be inoperable. Investigation into the cause of the condition is in progress. There were no related work activities in progress at the time the condition was identified. The licensee notified the NRC Resident Inspector. | Core Spray | 05000373/LER-2017-006 |
| ENS 52556 | 16 February 2017 14:35:00 | 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 | Secondary Containment Inoperable Due to Interlock Failure | This report is being made in accordance with 10 CFR 50.72(b)(3)(v)(C), for an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. An employee entered a secondary containment airlock and identified that both doors of the airlock opened simultaneously when the door on the reactor building side was opened. The employee immediately secured both doors in the airlock and notified the Main Control Room Supervisor. Both doors in the airlock were open for approximately 5 seconds. With both doors open, Technical Specifications (TS) Surveillance Requirement (SR) 3.6.4.1.2 was not met. This rendered secondary containment inoperable in accordance with TS 3.6.4.1. Reactor Building differential pressure, as observed in the Main Control Room, has remained more negative than -0.25 inches of vacuum water gauge at all times. Initial investigation determined that the interlock for the doors was malfunctioning. Administrative controls have been put in place to ensure the doors remain closed pending repairs to the interlock. The licensee informed the NRC Resident Inspector. | Secondary containment | |
| ENS 52519 | 31 January 2017 01:08:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | One Division Emergency Diesel Generator Cooling Water System Declared Inoperable | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. During routine surveillance testing of the Unit 2 Division 3 Emergency Diesel Generator (LOS-DG-M3), the Cooling Water Strainer Backwash Valve, 2E22-F319, was identified to have stem/disk separation and could not be opened. This condition has been evaluated and the Division 3 Diesel Generator Cooling Water system has been declared inoperable. The Division 3 Diesel Generator Cooling Water system is a support system for the Division 3 Emergency Diesel Generator and the High Pressure Core Spray System (HPCS). The required actions of Technical Specification (TS) 3.5.1 were entered on 1/30/17 at 1908 CST when the HPCS system was determined to be inoperable. This condition could have prevented the HPCS, a single train safety system, from performing its design function. The licensee has notified the NRC Resident Inspector. | Emergency Diesel Generator High Pressure Core Spray | |
| ENS 52496 | 19 January 2017 02:56:00 | 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 | Both Secondary Containment Airlock Doors Open Simultaneously | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(C), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and 10 CFR 50.72(b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. An employee entered a secondary containment interlock (airlock) and identified that both doors of the interlock opened simultaneously when the door on the reactor building side was opened. The employee immediately secured both doors in the interlock and notified the Main Control Room Supervisor. Both doors in the interlock were open for approximately five seconds. With both doors open, TS SR 3.6.4.1.2 was not met. This rendered secondary containment inoperable per TS 3.6.4.1. Reactor Building differential pressure, as observed in the Main Control Room has remained less than -0.25 in. H2O at all times. Initial investigation determined that the interlock for the doors was malfunctioning. Administrative controls have been put in place to ensure the doors remain closed pending repairs to the interlock. The licensee notified the NRC Resident Inspector. Notified R3DO (McCraw). | Secondary containment | |
| ENS 51741 | 17 February 2016 16:35:00 | 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 | Secondary Containment Inoperable Due to Door Interlock Malfunction | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(C), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and 10 CFR 50.72(b)(3)(v)(D), an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. An employee entered a secondary containment interlock and identified that both doors of the interlock opened simultaneously when the door on the reactor building side was opened. The employee immediately secured both doors in the interlock and notified the Main Control Room Supervisor. Both doors in the interlock were open for approximately 5 seconds. With both doors open, TS SR 3.6.4.1.2 was not met. This rendered secondary containment inoperable per TS 3.6.4.1. Reactor Building differential pressure, as observed in the Main Control Room, has remained less than -0.25 inches H20 at all times. Initial investigation determined that a mechanical interlock for the doors was malfunctioning. Administrative controls have been put in place to ensure the doors remain closed pending repairs to the interlock. The licensee has notified the NRC Resident Inspector. | Secondary containment | 05000374/LER-2016-001 |
| ENS 51725 | 11 February 2016 04:07:00 | 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 | Secondary Containment Inoperable | This report is being made pursuant to 10CFR50.72(b)(3)(v)(C), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and 10CFR50.72(b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. LaSalle Station's Unit 1 and Unit 2 were in Mode 1. At 2207 (CST) (on 2/10/16), Secondary Containment Differential Pressure dropped below the Technical Specification (TS) 3.6.4.1 minimum of 0.25 inches water vacuum. The initial indications are a failure of one Unit 1 Reactor Building Exhaust Isolation Damper, which resulted in a trip of the Unit 1 Reactor Building Exhaust Fans. At 2245, Secondary Containment Differential Pressure was restored to within the TS 3.6.4.1 limits by securing and isolating the Unit 1 Reactor Building Ventilation System. Troubleshooting plans are being developed to determine cause of the damper failure and to correct the deficient condition. The licensee has notified the NRC Resident Inspector. | Secondary containment Reactor Building Ventilation | 05000373/LER-2016-001 |
| ENS 50827 | 17 February 2015 17:45:00 | 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 | Containment Inoperable Due to Interlock Doors Open Simultaneously | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(C), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and 10 CFR 50.72(b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. LaSalle's Station Unit 1 was in Mode 1 and Unit 2 was in Mode 5 for its scheduled refuel outage. There was no movement of irradiated fuel or CORE ALTERATIONS at the time. OPDRVs (Operations with Potential to Drain the Reactor Vessel) were in progress in the secondary containment on Unit 2. An employee entered a secondary containment interlock and identified that both doors of the interlock opened simultaneously when the door on the reactor building side was opened. The employee immediately secured both doors in the interlock and notified the main control room supervisor. Both doors in the interlock were open for somewhere between 5-10 seconds. With both doors open, TS SR 3.6.4.1.2 was not met and this rendered secondary containment inoperable per TS 3.6.4.1. Reactor building differential pressure, in the main control room, was never observed to be less than -0.25 inches of water column. Initial investigation determined that the interlock for the doors was malfunctioning. Administrative controls have been put in place to ensure the doors remain closed pending repairs to the interlock. The NRC Resident Inspector has been notified. | Secondary containment | 05000373/LER-2015-003 |
| ENS 50707 | 30 December 2014 05:30:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Spray Declared Inoperable Due to Leak on Division 3 Diesel Generator Cooling Water Pump | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. During routine surveillance testing of the Unit 2 Division 3 Emergency Diesel Generator (LOS-DG-M3) a small pinhole leak was identified in the pump casing of the Division 3 Diesel Generator Cooling Water Pump. This condition has been evaluated and the Division 3 Diesel Generator Cooling Water Pump has been declared inoperable. The Division 3 Diesel Generator Cooling Water Pump is a support system for the Division 3 Emergency Diesel Generator and the High Pressure Core Spray System (HPCS). The required actions of Technical Specification (TS) 3.5.1 were entered on 12/29/14 at 2330 (CST) when the HPCS system was determined to be inoperable. This condition could have prevented the High Pressure Core Spray System (HPCS), a single train safety system, from performing its design function. The licensee notified the NRC Resident Inspector. | Emergency Diesel Generator High Pressure Core Spray | 05000374/LER-2015-001 |
| ENS 50674 | 12 December 2014 19:24:00 | 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 | Both Secondary Containment Airlock Doors Opened Simultaneously | This report is being made pursuant to 10CFR50.72(b)(3)(v)(C), 'Event or Condition that could have prevented fulfillment of a Safety Function needed to Control the Release of Radioactive Material' and 10CFR50.72(b)(3)(v)(D), 'Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident.' Unit 1 and Unit 2 were in Mode 1 and no movement of irradiated fuel, core alterations, or OPDRVs (Operations with the Potential to Drain the Reactor Vessel) were in progress in the secondary containment. An employee entered a secondary containment interlock and identified that both doors of the interlock opened simultaneously when the door on the reactor building side was opened. The employee immediately secured both doors in the interlock and notified the Main Control Room Supervisor. Both doors in the interlock were open for approximately 10 seconds. With both doors open, TS SR 3.6.4.1.2 was not met. This rendered secondary containment inoperable per TS 3.6.4.1. Reactor building differential pressure, as observed in the Main Control Room, has remained less than -0.25 inches of water column at all times. Initial investigation determined that the interlock for the doors was malfunctioning. Administrative controls (barricades and signs) have been put in place to ensure the doors remain closed pending repairs to the interlock. The licensee notified the NRC Resident Inspector. | Secondary containment | 05000373/LER-2015-001 |
| ENS 50413 | 28 August 2014 17:27:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Auxiliary Electric Equipment Room Hvac Inoperable | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. While the 'B' train of Auxiliary Electric Equipment Room HVAC was inoperable and out of service for emergent repairs due to an oil leak, the 'A' train of Auxiliary Electric Equipment Room HVAC became inoperable due to a failure of the liquid line solenoid valve. The Main Control Room Envelope consists of the Main Control Room and the Auxiliary Electric Equipment Room. Both the Control Room HVAC and the Auxiliary Electric Equipment Room HVAC systems are required to be operable in the current mode. This is a loss of safety function for a system that is intended to mitigate the consequences of an accident and is discussed in chapter 6 of the UFSAR and is Tech Spec required and is safety related. Also, the system, structure, or component (SSC) is inoperable in a required mode in the Tech Spec applicability and there is no redundant equipment in the same system that is operable. The required actions of Tech Spec 3.7.5 were entered for this event. Online Risk remains Green. The station is currently pursuing repairs to both trains. The licensee notified the NRC Resident Inspector. | HVAC | 05000373/LER-2014-004 |
| ENS 50076 | 30 April 2014 15:37:00 | 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 | Momentary Loss of Secondary Containment Due to Airlock Interlock Malfunction | This report is being made pursuant to 10CFR50.72(b)(3)(v)(C), Event or Condition that could have prevented fulfillment of a Safety Function needed to Control the Release of Radioactive Material and 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. Unit 1 was in mode 1 and in a condition of moving irradiated fuel in the secondary containment. Unit 2 was in mode 5 and in the condition of moving irradiated fuel in the secondary containment, core alterations, and operations with the potential to drain the reactor vessel. An employee entered a secondary containment interlock (Unit 2) and identified that both doors of the interlock opened simultaneously when the door on the auxiliary building side was opened. The employee immediately secured both doors in the interlock and notified the Main Control Room Supervisor. Both doors in the interlock were open for approximately 5 seconds. With both doors open, TS SR 3.6.4.1.2 (Technical Specification Surveillance Requirement) was not met. This rendered secondary containment inoperable per TS 3.6.4.1. Reactor Building differential pressure, as observed in the Main Control Room, has remained less that -0.25 inches of water column at all times. Initial investigation determined that the interlock for the doors was malfunctioning. Administrative controls have been put in place to ensure the doors remain closed pending repairs to the interlock. The licensee has notified the NRC Resident Inspector. | Secondary containment | 05000373/LER-2014-003 |
| ENS 49973 | 29 March 2014 21:20:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Division 3 Core Standby Cooling System Ventilation Failed | This report is being made pursuant to SAF 1.8, 10 CFR 50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. During steady state operations on Unit 1 at 1620 (CDT) hrs. on 3/29/14, the Division 3 Core Standby Cooling System (CSCS) Pump Room, SWGR Room, and Battery Room Ventilation failed in such a manner that heat could not be removed from the rooms. These Division 3 systems supply power and cooling water to the High Pressure Core Spray system (HPCS), which is a single-train system. The HPCS system and its associated power supplies were declared inoperable based on long-term temperature considerations. The system remains available due to manual damper adjustments that than can be made per an approved procedure. The licensee will notify the NRC Resident Inspector. | High Pressure Core Spray Core Standby Cooling System | 05000373/LER-2014-002 |
| ENS 49840 | 19 February 2014 00:20:00 | 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 | Momentary Loss of Secondary Containment | This report is being made pursuant to 10CFR50.72(b)(3)(v)(C), Event or Condition that could have prevented fulfillment of a Safety Function needed to Control the Release of Radioactive Material. An employee entered a secondary containment (airlock) interlock and identified that both doors of the interlock opened simultaneously when the door on the reactor building side was opened. The employee immediately secured both doors in the interlock and notified the Main Control Room Supervisor. Both doors in the interlock were open for approximately 3 seconds. With both doors open, TS SR 3.6.4.1.2 was not met. This rendered secondary containment inoperable per TS 3.6.4.1. Reactor Building differential pressure, as observed in the Main Control Room, has remained less than -0.25 inches H2O at all times. Initial investigation determined that a mechanical interlock for the doors was malfunctioning. Administrative controls have been put in place to ensure the doors remain closed pending repairs to the mechanical interlock. The licensee notified the NRC Resident Inspector. | Secondary containment | 05000373/LER-2014-001 |
| ENS 49574 | 23 November 2013 01:20:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Hvac Inoperable | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. While the 'A' Train of Control Room HVAC was inoperable and out of service for emergent repairs due to a Freon leak, the 'B' Train of Auxiliary Electric Room HVAC became inoperable due to a failure of the Cooler Condenser Fan. The Main Control Room Envelope consists of the Main Control Room and the Auxiliary Electric Equipment Room. Both the Control Room HVAC and the Auxiliary Electric Equipment Room HVAC Systems are required to be Operable in the current Mode. This is a loss of safety function for a system that is intended to mitigate the consequences of an accident and is discussed in Chapter 6 of the UFSAR and is Tech Spec required and is Safety Related. Also, the system, structure, or component (SSC) is inoperable in a required mode in the Tech Spec Applicability and there is no redundant equipment in the same system that is operable. The Required actions of Tech Spec 3.7.5 were entered on 11/22/2013 at 1920 CST when the 'B' train became inoperable. Online Risk remains Green. The station is currently pursuing repairs to both trains. The NRC Resident Inspector has been notified by the licensee. | HVAC | 05000373/LER-2013-008 |
| ENS 49167 | 1 July 2013 22:05:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Spray Minimum Flow Valve Pressure Switch Setpoint Found Outside of Tolerance | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. During routine Instrument Maintenance Surveillance Testing (LIS-HP-205), the High Pressure Core Spray System (HPCS) minimum flow valve pressure switch set point was found outside the Technical Specification allowable value. This could have prevented the High Pressure Core Spray System (HPCS), a single train safety system, from performing its design function. This is reportable as an 8 hour ENS notification. The required actions of Technical Specification (TS) 3.5.1 were entered on 7/01/13 at 1646 (CDT) when the system was made inoperable for surveillance testing. At 1705, maintenance personnel reported minimum flow valve pressure switch set point was found at 112.6 psig, which is outside of the TS Allowable Value of greater than or equal to 113.2 psig (0.6 psig below the Allowable Value). The minimum flow valve pressure switch set point has been calibrated and was left within Technical Specification allowable values, HPCS was declared OPERABLE at 1815 on 7/01/13." The licensee has notified the NRC Resident Inspector.
The event notification was reported by LaSalle Generating Station on 7/01/2013 at 2147 EDT. This update is being provided for the purposes of retracting that notification. On July 1, 2013, during surveillance testing, the Unit 2 High Pressure Core Spray System (HPCS) minimum flow valve pressure switch setpoint was found below the Technical Specification (TS) 3.3.5.1 allowable value. HPCS was declared inoperable, and TS Required Actions (RA) were entered on July 1, 2013, at 1646 hours (CDT). Because HPCS is a single train system, an ENS report was made pursuant to 10 CFR 50.72(b)(3)(v)(D), as an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. The minimum flow valve pressure switch setpoint was calibrated to within TS allowable values, and HPCS was declared operable on July 1, 2013, at 1815 hours. A post-event review determined that declaring HPCS inoperable was not required. The inoperability of the pressure switch would not have impacted the function of the HPCS minimum flow valve to automatically open as required to prevent overheating of the HPCS pump. The as-found setpoint was 0.6 psig below the TS allowable value, which would have resulted in the minimum flow valve opening slightly sooner. The inoperability would also not have prevented or delayed the automatic closing of the valve at the required system flow to assure that adequate ECCS flow is available. It should be noted that the LaSalle ECCS (Emergency Core Cooling System) LOCA (Loss Of Coolant Accident) analysis assumes that the HPCS minimum flow valve is open during an injection. TS 3.3.5.1 RA D.4 requires that the minimum flow valve pressure switch be restored to operable status within 7 days. If it cannot be restored within that time, RA G.1 requires that the supported system (HPCS) be declared inoperable, precluding extended operation with the minimum flow pressure switch inoperable. The pressure switch was re-calibrated to within TS allowable values within approximately 1 hour and 29 minutes of being declared inoperable. Therefore, the HPCS system was operable with the minimum flow pressure switch 0.6 psig out of calibration for 1 hour and 29 minutes. This event did not constitute a loss of safety function of the HPCS system, and the event was not reportable under 10 CFR 50.72(b)(3)(v)(D). The licensee has notified the NRC Resident Inspector. Notified R3DO (Lara). | High Pressure Core Spray | |
| ENS 48943 | 18 April 2013 19:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Pin Holes Leaks Identified in High Pressure Core Spray System | High Pressure Core Spray | 05000374/LER-2013-001 | |
| ENS 48966 | 18 April 2013 18:25:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Low Pressure Core Spray Inoperable | On 4/18/2013, while attempting to raise Unit 1 reactor level with the Low Pressure Core Spray (LPCS) system, LPCS injection valve 1E21-F005 failed to open as required when the associated control switch was held in the 'OPEN' position. The Unit Supervisor declared the LPCS system inoperable, and the appropriate Technical Specification time clocks were entered. Troubleshooting determined that the problem was a faulty control switch. The control switch has been replaced and LPCS returned to an operable status. Initial review of this event determined that it was not reportable; however, subsequent review caused the event to be re-evaluated and classified as reportable under 10CFR50.72(b)(3)(v)(D) and 50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. The station is continuing to evaluate the reportability of this event. The licensee notified the NRC Resident Inspector. | Core Spray | |
| ENS 48263 | 31 August 2012 14:40:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Spray Diesel Generator Declared Inoperable | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. During the conduct of the Unit 2 Division 3 High Pressure Core Spray (HPCS) Diesel Generator (DG) air start system receiver blowdown, a low air pressure system alarm was received. Starting air pressure in one of 2 redundant air receiver banks lowered to the point requiring the DG to be declared inoperable per Technical Specifications. This event appears to have been caused by a degraded receiver drain valve. The air system degraded equipment condition has cleared and the DG has been restored to operable status following 42 minutes of inoperability. Although a redundant air bank was fully available and charged, during this time of inoperability the DG was at reduced margin to successfully start if required. Due to this loss of margin and inoperable condition, it has been determined that this failure could potentially affect the safety function of this system, and is being reported as an 8 hour ENS notification. The licensee informed the NRC Resident Inspector. | High Pressure Core Spray | 05000374/LER-2012-001 |
| ENS 47509 | 7 December 2011 20:58:00 | 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 | Reactor Building Ventilation Differential Pressure Above Technical Specifications | This report is being made pursuant to 10CFR50.72(b)(3)(v)(C) and (D), event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and mitigate the consequences of an accident. Following initial troubleshooting of the reactor building ventilation (VR) differential pressure (DP) control loop, the Unit 1 VR DP controller was left in manual per the troubleshooting steps. It was noted at 1458 CST, on 12/7/11, that building DP was above the TS SR 3.6.4.1.1 required value of -0.25" H20. This rendered the secondary containment inoperable. Reactor building DP was returned to within the TS requirements within 14 minutes, and following system walkdowns, secondary containment was declared operable at 1615 (CST, on) 12/7/11. Troubleshooting will continue with other excursions above -0.25" H2O possible until repairs are complete (anticipated being complete week of 12/12/11). This condition requires the licensee to comply with technical specifications values within 4 hours or be in Mode 3 within 12 hours. The licensee has notified the NRC Resident Inspector. * * * RETRACTION FROM R. DRAPER TO P. SNYDER ON 12/22/11 AT 1440 EST * * * On December 7, 2011, following initial troubleshooting of the reactor building ventilation (VR) differential pressure (DP) control loop, the building DP was above the TS SR 3.6.4.1.1 value of -0.25 inch of vacuum water gauge. The secondary containment was declared inoperable and determined to be a loss of safety function. During the investigation it was determined that the event occurred due to a failure in the non-safety reactor building ventilation differential pressure control loop. The safety related function of the secondary containment and the non-safely reactor building ventilation differential pressure control loop are completely independent from one another. It is recognized that reactor building DP may exceed the TS SR (Technical Specification Surveillance Requirement) 3.6.4.1.1 value due to non-safety related component failures such as system fan trips, pressure controller malfunctions, rapid air temperature changes due to blast heater trips, or station heat recovery coil issues. A failure of a non-safety component does not result in a loss of safety function. The safely function of the secondary containment is maintained by adequate leak tightness and the operable ventilation equipment required to maintain the negative pressure requirements of TS SR 3.6.4.1.1. The safety related Stand-By Gas Treatment (SGT) ventilation system performs the negative pressure safety function. The secondary containment isolation safety function, isolation dampers and SGT systems remained operable throughout the event. Therefore this event did not constitute a loss of safety function of secondary containment and this event is not reportable. The licensee notified the NRC Resident Inspector. Notified R3DO (Pelke). | Secondary containment Reactor Building Ventilation | |
| ENS 46279 | 25 September 2010 07:10:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Spray System Room Cooling Fans Found Not Operating | This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. During steady state operations 2VD05C, Division 3 Switchgear Room / Core Standby Cooling System (CSCS) Pump Room Supply Fan and 2VD07C, Division 3 Switchgear Room / Core Standby Cooling System (CSCS) Pump Room Return Fan were found not operating. Division 3 ventilation supplies cooling to the High Pressure Core Spray System (HPCS), which is a single-train system. At the time of this discovery, there was not assurance that the HPCS would fulfill its safety function without mitigating manual actions due to the fan failure, and thus this condition is reportable. Operators are now briefed to manually operate the fan if needed to maintain proper temperature conditions until maintenance begins, thus restoring system function. The licensee has notified the NRC Resident Inspector. | High Pressure Core Spray Core Standby Cooling System | 05000374/LER-2010-001 |
| ENS 44284 | 11 June 2008 22:03:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpcs Declared Inoperable | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. During steady state operations, a Division 3 AC ground alarm was received, followed by a trip of the 2VD05C Division 3 switchgear room / Core Standby Cooling System (CSCS) Pump Room Supply Fan. Division 3 supplies power to the High Pressure (Core Spray) (HPCS), which is a single-train system. Although the system remained functional and capable of vessel injection following the failure, the HPCS system and its associated power supplies were declared inoperable based on long-term temperature considerations. At 1703, the circuit breaker for the HPCS injection valve, which is a Primary Containment Isolation Valve (PCIV), was opened and the valve deenergized in the closed position to comply with Technical Specifications. Disabling the injection valve affects the safety function of the system (HPCS), and this is reportable as an 8-hour ENS notification. The cause of the ventilation fan motor trip has been determined to be a motor fault. Replacement of the fan motor is in progress. This event places the plant in a 14-day LCO per Technical Specification 3.5.1. Repairs are expected to be completed by 0700 on 6/12/08. The Reactor Core Isolation Cooling (RCIC) system is operable. The licensee notified the NRC Resident Inspector. | Reactor Core Isolation Cooling Primary containment Core Standby Cooling System | |
| ENS 41931 | 18 August 2005 19:40:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Core Spray System Inoperable | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to mitigate the consequences of an accident. During a scheduled 24 hour surveillance run of the 1B diesel generator, with the diesel generator paralleled to its associated Bus 143, an electrical fault occurred in the Division 3 AC system. This resulted in a trip of the normal System Auxiliary Feed breaker ACB 1432 to the bus. The diesel generator was manually tripped when it was subsequently identified that its associated cooling water pump was not running. With the 1B diesel generator tripped, the Division 3 AC system is de-energized. The consequence is a loss of the Unit 1 High Pressure Core Spray System. High Pressure Core Spray is a single train system that performs a safety function, and therefore, loss of the system is reportable as an 8 hour ENS notification under SAF 1.8. The required actions of Technical Specification 3.5.1 for the High Pressure Core Spray System were entered on 8/18/05 at 14:40 when the system was made inoperable. All other Emergency Core Cooling Systems are operable at this time. The High Pressure Core Spray system is also unavailable, and On Line Risk for Unit 1 is Yellow. The system has been quarantined, and an investigation is currently in progress to determine the cause of the electrical fault. Unit 2 is not affected by this event, and Unit 1 is in a 14 day LCO to repair the EDG. The licensee notified the NRC Resident Inspector. | High Pressure Core Spray Emergency Core Cooling System | 05000373/LER-2005-004 |
| ENS 40476 | 25 January 2004 17:10:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Inoperable Refueling Interlock | This report is being made pursuant to 10CFR50.72(b)(3)(v)(A) and 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Maintain Safe Shutdown and Mitigate the Consequences of an Accident. During Unit 1 refueling operations, it was discovered at 1110 hours 1/25/04 CST that the Refuel Position One-Rod-Out Interlock was inoperable. Because this interlock is credited for mitigating the 'Control Rod Removal Error During Refueling' event evaluated in the UFSAR, this is reportable as an 8 hour ENS notification. With the Unit 1 Mode Switch in REFUEL, the one-rod-out interlock function was tested per LaSalle Operating Surveillance LOS-RD-SR4. Since the acceptance criterion of this surveillance was not met, the interlock was declared inoperable and the required actions of Technical Specification 3.9.2 entered. Currently all control rod withdrawals are suspended and all control rods are fully inserted in core cells containing fuel assemblies. The Unit 1 Mode Switch is in Shutdown. Actions are in progress to restore the One-Rod-Out Interlock to an operable status. The licensee notified the NRC Resident Inspector.
During further investigation, it was determined that the system design is such that whenever the Mode Switch is placed in the REFUEL position with a rod withdrawn, no select block is received but a rod withdrawal block is generated. This design feature allows control rods to be inserted should the Mode Switch be placed in REFUEL with any rod out. The LaSalle Operating Surveillance (LOS-RD-SR4) used to demonstrate operability of the Refuel Position One-Rod-Out Block does not currently recognize this design feature and its acceptance criteria is based solely on receipt of the select block. The subject procedure will be revised to ensure all rods are fully inserted prior to performing the surveillance thereby ensuring the logic initial conditions are met to satisfactorily demonstrate the select block function. With these initial conditions satisfied, the Refuel Position One-Rod-Out Interlock was satisfactorily tested on 1/25/04 at 1935 hours CST. Therefore, the Refuel Position One-Rod-Out interlock performed as designed and was capable of performing its safety function. Thus, this occurrence was not reportable under 10CFR50.72(b)(3)(v)(A) and 10CFR50.72(b)(3)(v)(D)." The licensee notified the NRC Resident Inspector. Notified R3DO (Louden). | Control Rod | |
| ENS 40325 | 17 November 2003 07:10:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Event or Condition That Could Have Prevented Fulfillment of a Safety Function | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to mitigate the consequences of an Accident. During performance of scheduled surveillance test LIS-HP-310, Reactor Vessel High Water Level 8 (High Pressure Core Spray) HPCS Injection Valve Closure Instrument Channels A and B Functional Test, Instrument Maintenance personnel discovered one end of fuse 1B21A-F8 not fully seated. The other end of the fuse was fully seated, and was maintaining the un-clipped end in sufficient contact with the fuse holder to complete the circuit. Had the circuit been deenergized, a Control Room annunciator (1H13-P601 A404) would have alarmed, and High Pressure Core Spray (HPCS) automatic low level initiation circuits would have been disabled. The fuse was fully seated without incident. Upon discovery of the unseated fuse, the initial operability determination concluded that adequate contact was maintained to keep the circuit OPERABLE. After followup evaluation by Engineering, it was determined that continued OPERABILITY could not be assured during a seismic event. Failure of this fuse would prevent automatic actuation of HPCS on reactor vessel level low 2; and would prevent automatic closure of the HPCS discharge valve 1E22-F004 on reactor vessel level high 8. This would prevent the HPCS system, a single train safety system, from performing its design function during a Loss of Coolant Accident subsequent to a seismic event. This is reportable as an 8 hour ENS notification." The licensee informed the NRC Resident Inspector. | High Pressure Core Spray |