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 Entered dateSiteRegionReactor typeEvent description
ENS 5647117 April 2023 09:37:00LaSalleNRC Region 3GE-5The 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.
ENS 563894 March 2023 16:42:00LaSalleNRC Region 3GE-5The following information was provided by the licensee via email: At 0910 (CST), with Unit 2 in Mode 4 at 0 percent power, an actuation of a reactor scram on low charging water header pressure occurred during restoration from hydrostatic test conditions. All control rods were already fully inserted prior to the receipt of the scram signal. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Unit 2 RPS system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 563646 February 2023 13:26:00LaSalleNRC Region 3GE-5The following information was provided by Constellation via email: On 02/06/2023 at 0416 EST, the Constellation Emergency Response Organization (ERO) Notification Database System uploaded data files into the Mass Notification System (Everbridge) which is used to notify ERO personnel when activated. At 0630, the individual reviewing the uploaded files discovered that the data files did not upload properly and that Everbridge may not notify all ERO individuals within the required 10 minutes of system initiation. Constellation resolved the issue by 0752. During the time period of 0416 to 0752, control room operators would have been unaware that the ERO notification was not successful. Therefore, this issue constitutes a loss of offsite communications capability and is reportable under 10 CFR 50.72(b)(3)(xiii), 'The licensee shall notify the NRC as soon as practical and in all cases within eight hours of the occurrence of any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability (e.g., significant portion of control room indication, Emergency Notification System, or offsite notification system).' This loss of offsite communications capability affected all Constellation nuclear stations. There was no impact on the health and safety of the public or plant personnel. Each affected station NRC Resident Inspectors have been or will be notified.
ENS 562034 November 2022 08:04:00LaSalleNRC Region 3GE-5The 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 5612026 September 2022 06:39:00LaSalleNRC Region 3GE-5The following information was provided by the licensee via fax email: At 0238 CDT on 9/26/2022 with Unit 2 in Mode 1 at 100 percent power, the reactor manually tripped due to a reported fire on the isophase bus duct. The trip was uncomplicated with all systems responding normally post-trip with the exception of the 2A reactor protection system power supply, which tripped and power was transferred to the alternate source. The fire was reported extinguished at 0240 CDT on 9/26/2022. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Operations responded using the emergency operating procedure LGA-001 and stabilized the plant in Mode 3. Decay heat is removed by discharging steam to the main condenser using the turbine bypass valves. Unit 1 is not affected. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5590823 May 2022 19:15:00LaSalleNRC Region 3GE-5The 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 5590520 May 2022 17:39:00LaSalleNRC Region 3GE-5The 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 5578814 March 2022 18:30:00LaSalleNRC Region 3GE-5The following information was provided by the licensee via fax or email: At 1338 CDT on 3/14/2022, it was determined that a contract supervisor tested positive during a random fitness-for-duty test. The individual's authorization for site access has been terminated. The NRC Resident Inspector has been notified.
ENS 557231 February 2022 16:24:00LaSalleNRC Region 3GE-5The following information was provided by the licensee via fax or email: At approximately 1328 CST on 2/1/2022, LaSalle Generating Station was made aware of the following event that resulted in additional county emergency sirens sounding. The Grundy County monthly siren test had issues with siren activation from the County's primary controller. The buttons to activate were being pressed, but the intended sirens were not initiating. The Grundy County operator continued to attempt activation unknowingly activating the sirens in the Northeast quadrant several times between 1000-1015 CST. This event is reportable per 10 CFR 50.72(b)(2)(xi), News Release or Notification of Other Government Agencies. This is a 4-Hour Reporting requirement. The LaSalle NRC Resident has been notified.
ENS 552406 May 2021 17:05:00LaSalleNRC Region 3GE-5This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation of containment isolation valves in more than one system required by 10 CFR 50.73(a)(2)(iv)(A). On March 10, 2021, at 0815 (CST), during the Unit 2 Refueling Outage (L2R18), while performing a test to verify functionality of an isolation relay following replacement of the relay, a Group 4 isolation signal was actuated. The Group 4 isolation logic affects both the Reactor Building Ventilation (VR) and Containment Vent and Purge (VQ) system (for both units). All equipment responded as designed to the Group 4 isolation, including startup of Standby Gas Treatment (SBGT) to maintain secondary containment pressure (for both units). Investigation determined that the cause of the isolation was an inadvertent contact of the self-retracting grip jumper between two adjacent terminals that caused a short to ground and a blown fuse during the test performance. The fuse was replaced and systems restored as needed for the plant condition. The containment isolation was not due to actual plant conditions or parameters meeting design criteria for containment isolation. Therefore, this is considered an invalid actuation. The NRC Resident Inspector has been informed of this notification.
ENS 5511526 February 2021 22:52:00LaSalleNRC Region 3GE-5This telephone notification is provided in accordance with 10 CFR 26.719(b), to report a significant fitness-for-duty event under 10 CFR 26.719(b)(2)(ii). A contractor supervisor was found in violation of the fitness-for-duty policy. The employee's access to the plant has been revoked. The NRC Resident Inspector has been notified. In addition, the licensee notified the Illinois Emergency Management Agency.
ENS 5508629 January 2021 02:43:00LaSalleNRC Region 3GE-5This is an eight-hour, non-emergency notification for a loss of Emergency Assessment Capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii) because the Technical Support Center (TSC) Supply Fan belt had failed which affects the functionality of an emergency response facility. Corrective maintenance activities are being performed on January 29, 2021 to the TSC HVAC (heating, ventilation, and air conditioning system). The work includes replacing the failed belt and restarting the TSC Supply Fan. The work duration is approximately 12 hours. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures unless the TSC becomes uninhabitable due to ambient temperature, radiological, or other conditions. If relocation of the TSC becomes necessary, the Emergency Director will relocate the TSC staff to an alternate location in accordance with applicable site procedures. The Emergency Response Organization team has been notified of the maintenance and the possible need to relocate during an emergency. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The licensee will be notifying the Illinois Emergency Management Agency.
ENS 5504623 December 2020 12:28:00LaSalleNRC Region 3GE-5At 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.
ENS 546934 May 2020 23:40:00LaSalleNRC Region 3

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.

  • * * RETRACTION ON MAY 8, 2020 AT 1709 EDT FROM JOE MESSINA TO BRIAN LIN * * *

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).

ENS 5438412 November 2019 18:23:00LaSalleNRC Region 3This report is being made pursuant to 10CFR50.72(b)(2)(xi), "News Release or Notification of Other Government Agency". The Main Control Room received a report from on-site Maintenance personnel performing diving activities at the lake screen house that communications with a diver had been lost. Onsite and offsite emergency responders were dispatched. The diver was removed from the water but was unresponsive. At 1601 (CST), the LaSalle County Station Operating Department was notified by emergency responders on-site that the individual was deceased. The Grundy County Sheriff, LaSalle County Sheriff, Seneca Emergency Services, and NRC Senior Resident Inspector have been notified. A press release is planned
ENS 539031 March 2019 04:03:00LaSalleNRC Region 3On February 28, 2019, at 2217 CST, LaSalle Unit 2 experienced a trip of the 241Y Safety Related Bus during surveillance testing resulting in a valid undervoltage actuation signal to the Common Emergency Diesel Generator ('O' EDG), causing it to start and load to Bus 241Y. The purpose of the surveillance testing was to demonstrate the operability of the breakers necessary to provide the second off site source to Unit 2. This event is reportable in accordance with 10 CFR 50.72(b)(3)(iv)(A), as an event that results in a valid actuation of the emergency AC electrical power system. In addition to the 241Y bus trip and 'O' EDG actuation signal, the following plant responses occurred as designed due to the momentary loss of this AC Bus: "A" RPS de-energized due to the loss of the 2A Reactor Protection System Motor-Generator Set, and the running Unit 2 Fuel Pool Cooling pump tripped. The Non-Safety Related Bus 241X de-energized resulting in a trip of the Unit 2 Station Air Compressor. All systems have been restored and troubleshooting is currently in progress. Unit 1 remained in MODE 1 during this event. The NRC Senior Resident Inspector has been notified.
ENS 5357631 August 2018 23:26:00LaSalleNRC Region 3This notification is being provided in accordance with 10 CFR 50.72(b)(2)(iv)(B). On August 31, 2018 at 2105 CDT, Unit 2 Reactor Manual Scram signal was inserted due to Main Condenser vacuum degrading. The turbine was tripped following the scram. Main Condenser vacuum is at 6 inches of backpressure slowly improving following the scram and turbine trip. During the scram, one Control Rod (30-31) did not fully insert. Control Rod 30-31 has been manually inserted to position 00 with the first position identified as position 24. Plant is in a stable condition with reactor pressure being maintained by the Turbine Bypass valves. Reactor water level is being controlled with feedwater. Investigation into the cause of the elevated condenser in leakage is in progress. The Senior NRC Resident has been notified.
ENS 5327622 March 2018 07:07:00LaSalleNRC Region 3GE-5This notification is being provided in accordance with 10CFR50.72(b)(2)(i), Plant Shutdown required by Technical Specifications, and 10 CFR 50.72(b)(3)(ii)A, Degraded or Unanalyzed Condition. At 0300 CDT on 3/22/18, on LaSalle Unit 1, a through-wall (welded joint) leak was identified on a 3/4 inch vent line off of the bonnet of the 1B33-F067B, 1B Reactor Recirculation Pump Discharge Valve. This condition qualifies as pressure boundary leakage, which requires entry into Technical Specification 3.4.5, Reactor Coolant System Operational Leakage, Required Action C, to be in Mode 3, Hot Shutdown, by 1500 on 3/22/18 and Mode 4, Cold Shutdown, by 1500 on 3/23/18. This leakage is significantly less than 10 gallons per minute and therefore, does not meet the threshold for entry into the Emergency Action Plan. At the time of discovery, Unit 1 was in Mode 1 - Run. Shutdown began at 0500 CDT and the estimated completion to cold shutdown is 2000 CDT. All necessary shutdown equipment is available. There is no impact to Unit 2. NRC Resident Inspector was notified.
ENS 5321917 February 2018 10:29:00LaSalleNRC Region 3GE-5This 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.
ENS 5321315 February 2018 13:39:00LaSalleNRC Region 3GE-5On 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 5308321 November 2017 14:22:00LaSalleNRC Region 3GE-5On October 6, 2017 at 0910 CDT hours, with Unit 1 in Mode 1 (Power Operation), the 1A Diesel Generator Cooling Water Pump (DGCWP) automatically started. The cause was the misoperation of the 1B/C RHR (Residual Heat Removal) Room Cooler Fan (1VY03C) control switch, which was placed in the start position instead of the intended pull-to-lock position. The start of the 1VY03C fan resulted in the automatic actuation of the 1A DGCWP. This system actuation is reportable in accordance with 10CFR50.73(a)(2)(iv)(A). The invalid actuation was not part of a pre-planned sequence during testing or reactor operation. The 1A DGCWP, an emergency service water system that does not normally run and that serves as an ultimate heat sink, responded satisfactorily. This call is being made in accordance with 10CFR50.73(a)(1), which states that in the case of an invalid actuation reported under 10CFR50.73(a)(2)(iv), other than an actuation of the reactor protection system when the reactor is critical, the licensee may provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written Licensee Event Report. The licensee notified the NRC Resident Inspector.
ENS 5282123 June 2017 01:00:00LaSalleNRC Region 3GE-5

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 FROM RICHARD IMMKE TO DONALD NORWOOD AT 1518 EDT ON 6/23/2017 * * *

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).

ENS 5276117 May 2017 12:29:00LaSalleNRC Region 3GE-5This 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.
ENS 5256418 February 2017 02:58:00LaSalleNRC Region 3GE-5

This notification is being provided in accordance with 10CFR 50.72(b)(2)(iv)(B). On February 17, 2017 at 2353 CST, Unit 1 Reactor Automatic Scram signal was received due to Turbine Control Valves Fast Closure. The turbine trip was due to receipt of Level 8 Trip due to a failure of the Feedwater Regulating Valve to Full open. Plant is in a stable condition with reactor pressure being maintained by the Turbine Bypass valves. Reactor water level is being controlled with Feedwater thru the Low Flow Feedwater Regulating Valve. Further investigation into the cause of the event is in progress. All control rods fully inserted, and decay heat is being removed via steam to the main condenser using bypass valves. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE FROM BROCK POLLMANN TO HOWIE CROUCH AT 1721 EDT ON 4/14/17 * * *

Upon further review of the event data, it was determined that the Nuclear Station Operator (NSO) had initiated a manual scram, which was followed by a Turbine Control Valve (TCV) fast closure automatic scram when the turbine tripped. The licensee has notified the NRC Resident Inspector. Notified R3DO (Jeffers).

ENS 5255616 February 2017 13:54:00LaSalleNRC Region 3GE-5This 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.
ENS 5254714 February 2017 02:40:00LaSalleNRC Region 3GE-5This notification is being provided in accordance with 10 CFR 50.72(b)(2)(iv)(B). On February 13, 2017 at 2309 CST, a Unit 1 Reactor Automatic Scram signal was received due to Turbine Control Valve Fast Closure. The turbine trip was due to the main generator trip on Differential Current. The 'U' safety relief valve actuated in the relief mode on the turbine trip, and has subsequently reset with tailpipe temperature returning to normal. The plant is in a stable condition with reactor pressure being maintained by the Turbine Bypass valves. Reactor water level is being controlled with feedwater. Investigation into the cause of the event is in progress. All control rods fully inserted on the scram. Unit 1 is in a normal shutdown electric plant alignment. Unit 2 was not affected. The licensee notified the NRC Resident Inspector.
ENS 5251930 January 2017 23:34:00LaSalleNRC Region 3GE-5This 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.
ENS 5250523 January 2017 10:34:00LaSalleNRC Region 3GE-5This notification is being provided pursuant with 10 CFR 50.72 (b)(2)(iv)(B). (On January 23, 2017) at 0806 (CST), Unit 2 Manual Scram was inserted due to a Stator Water Cooling runback signal and a Turbine Bypass Valve opening. The Plant is stable, reactor pressure is being maintained with Bypass valves. Reactor water level is being controlled with feedwater. Investigation into the cause of the event is in progress. All control rods fully inserted. The licensee has notified the NRC Resident Inspector.
ENS 5249619 January 2017 00:39:00LaSalleNRC Region 3GE-5This 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).
ENS 524722 January 2017 17:49:00LaSalleNRC Region 3GE-5At approximately 1403 (CST) on January 2, 2017, LaSalle County Station was informed by the LaSalle County Sheriff that two warning sirens had malfunctioned at approximately 1252 earlier this afternoon. The warning sirens had inadvertently operated for nearly 3 minutes during maintenance at the LaSalle County 911 Communications Center. The warning sirens have been restored to standby and are fully functional. No other emergency notification systems or sirens were affected. The licensee has notified the NRC Resident Inspector of the issue.
ENS 522278 September 2016 14:50:00LaSalleNRC Region 3GE-5On July 11, 2016, at approximately 0430 CDT, while Unit 1 was operating at 100% power, the 1A Reactor Protection System (RPS) Motor Generator (M/G) set tripped causing a loss of the A RPS bus. This caused the complete actuation of the Division 1 (outboard) primary containment isolation logic. The isolation logic actuation resulted in successful closure of the Division 1 primary containment isolation valves. This was an event that resulted in the actuation of a general containment isolation signal affecting more than one system. However, as this event meets the definition of an invalid actuation (i.e., not a response to an actual plant parameter exceeding a trip set-point), this notification is being made in accordance with 10CFR50.73(a)(2)(iv)(A) in lieu of a Licensee Event Report. In response to the trip of the 1A RPS M/G Set, operators swapped the A RPS bus to the alternate power supply using the applicable response procedure. The containment isolation signal was reset and the systems were restored to their normal lineup. Reactor power was not affected by this event. All safety related equipment controlled by the affected primary containment isolation circuits operated as designed. The 1A RPS M/G Set trip was due to a blown power fuse for the 1A RPS M/G Set. This was the result of worn insulation on one of the generator output leads. The generator output leads were repaired and rerouted to prevent future problems on 07/15/16. Restoration of the normal power supply to the 1A RPS function was completed on 7/19/16. The licensee informed the NRC Resident Inspector.
ENS 5210418 July 2016 23:29:00LaSalleNRC Region 3GE-5This telephone notification is provided in accordance with the Exelon Reportability manual, 'Major Loss of Emergency Preparedness Capabilities', and 10 CFR 50.72(b)(3)(xiii). On July 18, 2016 at 1500 CDT, it was determined during testing of the Everbridge ERO (Emergency Response Organization) notification system that the system would not notify the corporate EOF (Emergency Operations Facility) individuals if the system had been activated. This constitutes a loss of offsite communication capability. Exelon and Everbridge have identified and corrected this issue. A follow-up test of the LaSalle Everbridge ERO notification system was completed satisfactorily on July 18, 2016 at 2100. The Emergency Response Data System (ERDS) capability was not lost. The licensee has notified the (NRC) Senior Resident Inspector of the issue. Compensatory measures were in place during this event.
ENS 5174117 February 2016 17:05:00LaSalleNRC Region 3GE-5This 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.
ENS 5172511 February 2016 01:20:00LaSalleNRC Region 3GE-5This 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.
ENS 5153011 November 2015 19:40:00LaSalleNRC Region 3GE-5At 1344 CST on 11/11/15, the seismic monitor was found inoperable. The seismic monitor was inoperable such that emergency classification at the ALERT level could not be obtained with site instrumentation. The loss of assessment capability is reportable to the NRC within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii). (The NRC) Senior Resident Inspector has been notified.
ENS 5131813 August 2015 16:52:00LaSalleNRC Region 3GE-5A licensed, non-supervisory employee had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The licensee notified the NRC Resident Inspector as well as the NRC Region 3 Office Safeguards Inspector.
ENS 513007 August 2015 19:58:00LaSalleNRC Region 3GE-5This notification is being provided in accordance with 10 CFR 50.72(b)(3)(ii)A, Degraded Condition. At 1340 CDT on 8/7/15, on LaSalle Unit 2, a through-wall (welded joint) leak was identified on a 3/4 inch vent line off of the bonnet of the 2B33-F067B, 2B Reactor Recirculation Pump Discharge Valve. This condition qualifies as pressure boundary leakage, which requires entry into Technical Specification 3.4.5, Reactor Coolant System Operational Leakage, Required Action C, to be in Mode 4, Cold Shutdown, by 0140 on 8/9/15. This leakage is significantly less than 10 gpm (leak rate is 0.2 gpm) and therefore, does not meet the threshold for entry into the Emergency Action Plan. At the time of discovery, Unit 2 was in Mode 3 - Hot Shutdown, heading into Cold Shutdown for a planned maintenance outage. This event does not affect Unit 1. The licensee notified the NRC Resident Inspector.
ENS 5124722 July 2015 07:08:00LaSalleNRC Region 3GE-5(At) 0013 CDT, (on) 7/22/15, the seismic monitor was found inoperable. The seismic monitor was inoperable such that emergency classification at the ALERT level could not be obtained with site instrumentation. The loss of assessment capability is reportable to the NRC within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii). (The NRC) Senior Resident Inspector has been notified.
ENS 512138 July 2015 21:53:00LaSalleNRC Region 3GE-5

This telephone notification is provided in accordance with Exelon Reportability manual SAF 1.10, 'Major Loss of Emergency Preparedness Capabilities', and 10CFR50.72(b)(3)(xiii). On July 8th 2015 at 1837 (CDT), it was determined that the onsite Technical Support Center (TSC) Ventilation System Supply Fan belts had failed, resulting in loss of ventilation for the facility. Repairs were not completed within the time required had the TSC needed to be staffed. There is currently no emergency event in progress requiring TSC staffing. If an emergency is declared and the TSC ERO (Emergency Response Organization) activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological, or other conditions. If relocation of the TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location in accordance with applicable site procedures. The licensee has notified the (NRC) Senior Resident Inspector of the issue.

  • * * UPDATE FROM TODD CASAGRANDE TO DANIEL MILLS AT 1510 EDT ON 7/11/15 * * *

After repairs were completed, the TSC Ventilation was restarted on 7/9/15 at 0625 EDT for a maintenance run, the TSC Ventilation was restored to operable status at 1500 EDT on 07/11/2015. The licensee has notified the NRC Resident Inspector. Notified R3DO (Stone).

ENS 512058 July 2015 07:04:00LaSalleNRC Region 3GE-5At 0130 (CDT) on 7/8/15, the seismic monitor was found inoperable. The seismic monitor was inoperable such that emergency classification at the Alert level could not be obtained with site instrumentation. The seismic monitor was restored to operable status within 11 minutes. The loss of assessment capability is reportable to the NRC within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii). The licensee has notified the NRC Resident Inspector.
ENS 5116417 June 2015 23:39:00LaSalleNRC Region 3GE-5

On June 17th, 2015 at 1841 CDT, it was determined that the onsite Technical Support Center (TSC) Ventilation System return damper 0VS119Y was failed closed, the failed closed damper affects the TSC Emergency Makeup Train filtration efficiency. There is currently no emergency event in progress requiring TSC staffing. If an emergency is declared and the TSC ERO (Emergency Response Organization) activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological, or other conditions. If relocation of the TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location in accordance with applicable site procedures. The licensee has notified the (NRC) Senior Resident Inspector of the issue.

  • * * UPDATE AT 1700 EDT ON 06/18/15 FROM TODD CASAGRANDE TO S. SANDIN * * *

After repairs were completed, the TSC Ventilation was restored to service at 1650 EDT on 06/18/2015. The licensee has notified the NRC Resident Inspector. Notified R3DO (Pelke).

ENS 511336 June 2015 17:22:00LaSalleNRC Region 3GE-5

The following was received via fax and phone: This telephone notification is provided in accordance with Exelon Reportabllity manual SAF 1.1 0, 'Major Loss of Emergency Preparedness Capabilities', and 10CFR50.72(b)(3)(xiii). On June 6th 2015 at 12:13 (CDT), it was determined that the onsite Technical Support Center (TSC) Ventilation System Supply Fan belts had failed, resulting in loss of ventilation for the facility. Repairs were not completed within the time required had the TSC needed to be staffed. There is currently no emergency event in progress requiring TSC staffing. If an emergency is declared and the TSC ERO activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological, or other conditions. If relocation of the TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location in accordance with applicable site procedures. The licensee has notified the Senior Resident Inspector of the issue.

      • UPDATE PROVIDED BY TODD CASAGRANDE TO NESTOR MAKRIS AT 2305 EDT ON 06/06/2015 ***

After repairs were completed, the TSC ventilation was restored to service at 2300 (EDT) on 06/06/2015. The licensee has notified the NRC Resident Inspector. Notified R3DO (Passehl) via email

ENS 510547 May 2015 17:51:00LaSalleNRC Region 3GE-5This report is being made pursuant to 10CFR50.72(b)(2)(xi), News Release or Notification of Other Government Agency. Operations received a report from Security that a fishing boat has capsized on the station cooling lake. At 1530 (CDT) the LaSalle County Operating Department was notified that the LaSalle County Coroner confirmed that there was a fatality. The Illinois Department of Natural Resources (IDNR), LaSalle County Sheriff, Seneca Rescue Team, and NRC Senior Resident Inspector have been notified.
ENS 5092626 March 2015 15:19:00LaSalleNRC Region 3GE-5

LaSalle Station has completed a review of seismic monitor performance. The seismic monitor is currently operable; however, this review identified 6 times in the past 3 years that the seismic monitor was inoperable such that emergency classification at the ALERT level could not be obtained with site instrumentation. The seismic monitor was determined to be inoperable on the following dates: 

 1) January 28, 2015
 2) May 28, 2014
 3) January 1, 2014
 4) August 5, 2013
 5) April 17, 2013
 6) April 10, 2012

These unplanned inoperable conditions of the seismic monitor were entered into the LaSalle Corrective Action Program when they occurred. While Exelon procedural direction allowed the use of offsite sources to obtain seismic data when the seismic monitor is incapable of assessing emergency plan Emergency Action Levels (EALs), this was not explicitly referenced in the approved EALs. The loss of assessment capability is reportable to the NRC within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii). This report is required per 10 CFR 50.72(a)(1)(ii) as an event that occurred within 3 years of the date of discovery. The licensee has notified the NRC Resident Inspector.

ENS 5082717 February 2015 15:35:00LaSalleNRC Region 3GE-5This 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.
ENS 5070730 December 2014 03:51:00LaSalleNRC Region 3GE-5This 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.
ENS 5067512 December 2014 21:15:00LaSalleNRC Region 3GE-5Engineering identified fuse and breaker coordination issues with Reactor Core Isolation Cooling (RCIC) valves operated at the Remote Shutdown Panel (RSDP). The coordination issues are such that, given a fire in the main control room, it is possible that RCIC valve power supply breakers could trip prior to tripping control power fuses. Operation of RCIC from the RSDP could be impaired in this scenario without compensatory actions to reset breakers. RCIC is the single credited source of makeup to the reactor pressure vessel during this scenario. The current licensing basis (Fire Protection Report) does not identify the compensatory actions required to reset breakers prior to RCIC operation at the RSDP. This condition is applicable to Unit 1 and Unit 2. This report is being made pursuant to 10CFR50.72(b)(3)(ii)(B), 'Event or Condition that results in an unanalyzed condition that significantly degrades plant safety'. Actions are being taken to amend the appropriate operating procedures to take the required steps to ensure proper operation of RCIC in the postulated scenario. The licensee has notified the NRC Resident Inspector.
ENS 5067412 December 2014 18:20:00LaSalleNRC Region 3GE-5This 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.
ENS 5046417 September 2014 09:21:00LaSalleNRC Region 3GE-5

This telephone notification is provided in accordance with 10CFR50.72(b)(3)(xiii), 'Major Loss of Emergency Preparedness Capabilities.' On September 17th, 2014, at 0800 (CDT), the Exelon LaSalle Station Technical Support Center (TSC) ventilation system was removed from service for planned TSC ventilation system maintenance. The removal of the ventilation system potentially affects the TSC habitability during a declared emergency requiring activation. The Emergency Response Organization (ERO) team has been notified of the maintenance and the possible need to relocate during an emergency. If an emergency is declared and the TSC ERO activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological, or other conditions. If relocation of the TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location in accordance with applicable site procedures. The ventilation system is expected to be out of service for approximately 4 hours. The licensee has notified the (NRC) Senior Resident Inspector of the issue.

  • * * UPDATE PROVIDED BY WAYNE CLAYTON TO JEFF ROTTON AT 1741 EDT ON 09/17/2014 * * *

The scheduled TSC ventilation system maintenance is expected to be out of service for approximately an additional 7 hours. The licensee has notified the NRC Senior Resident Inspector of the issue. Notified R3DO (Dickson)

ENS 5041328 August 2014 18:26:00LaSalleNRC Region 3GE-5This 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.
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