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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 50398 | 25 August 2014 13:12:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due Fire Alarm in Reactor Building | At 0757 CDT on 8/25/14, LaSalle Main Control Room received a fire alarm from the Unit 2 Reactor Building 807 foot elevation. Operators dispatched and confirmed no fire at 0817 CDT (20 min). At 0812 CDT (15 min) an unusual event (HU3) was declared due to not having verified no fire within 15 minutes of the alarm. No fire was confirmed and plans are in progress to terminate event. The NRC Resident Inspector has been notified. The licensee notified the Illinois Emergency Management Agency. Notified DHS SWO, FEMA Operation Center, FEMA National Watch Center, NICC, Nuclear SSA via email.
At 0915 CDT on 8/25/2014, the LaSalle Shift Emergency Director terminated the Unusual Event (HU3) which had been declared at 0812 CDT. No fire present was verified at 0817 CDT and required hourly firewatch is in place. Maintenance Department has begun efforts to locate and replace faulted detector or other degraded component. The licensee notified the NRC Resident Inspector and the Illinois Emergency Management Agency. Notified R3DO(Passehl), NRREO (Hiland), IRD (Gott). Notified DHS SWO, FEMA Operation Center, FEMA National Watch Center, NICC, Nuclear SSA via email. | ||
| ENS 48939 | 17 April 2013 20:11:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | Notification of Unusual Event Declared Due to Loss of Offsite Power from a Lightning Strike | LaSalle Unit 1 and LaSalle Unit 2 have both experienced an automatic reactor scram, in conjunction with a loss of offsite power. This was caused by an apparent lightning strike in the main 345kV/138kV switchyard during a thunderstorm. 138kV line 0112 has been inspected in the field, and heavy damage has been noted on the insulators on two of the three phases on a line lightning arrestor line side. The plant systems have all responded as expected. All five diesel generators started, and have loaded on to their respective buses as designed. All rods went full in on both units during the respective scrams. HPCS (High Pressure Core Spray) system was started on each unit and automatically aligned for injection for initial level control. The MSIVs (Main Steam Isolation Valves) are shut on both units with decay heat being removed via the safety relief valves. Suppression pool cooling is in progress. The licensee will notify the NRC Resident Inspector and has notified the State. Notified DHS, FEMA, USDA, HHS, DOE, NICC, EPA, and Nuclear SSA via email.
In addition to information (previously provided), LaSalle Unit 2 received a high drywell pressure signal (1.77 psig) due to loss of containment cooling from the loss of power. At the time of this high drywell pressure signal, high pressure core spray pump and 2B residual heat removal (RHR) pump was already in operation, the low pressure core spray system and 2A residual heat removal system was secured and (placed) in pull to lock. When the signal was satisfied the ECCS (Emergency Core Cooling Systems) signal was processed but only the 2C RHR pump would have started. In this case, the 2C RHR pump tripped when the signal was received. There is no evidence of reactor coolant leakage. There was no additional ECCS systems discharging into the RCS (Reactor Coolant System). As (initially stated), level was controlled using High Pressure Core Spray and level control is now being maintained using the Reactor Core Isolation Cooling (RCIC) systems. The 2C RHR pump trip is under investigation. Due to the initial loss of offsite power for both Unit 1 and Unit 2 reported at 1511 (CDT), multiple containment isolation valves isolated and closed as expected. Once initial containment isolations were verified, two Unit 2 primary containment vent and purge valves were opened to vent the Unit 2 containment. Once Unit Two containment pressure reached 1.77 (psig), these two vent valves isolated as expected. Due to the loss of offsite power, the Station Vent Stack Wide Range Gas Monitor (WRGM) and the Standby Gas Treatment Wide Range Gas Monitor (VGWRGM) also lost power. Manual sampling has been implemented and power is restored to the VGWRGM, however the VGWRGM has not been declared operable yet. Normal radiation levels have been reported from the manual sampling. (This is being reported in accordance with 10CFR50.72(b)(3)(xiii).) The licensee notified the NRC Resident Inspector and the State of Illinois. Notified the R3 IRC, NRR EO(Skeen), IRD MOC (Grant).
After the Unit 2 primary containment vent and purge system isolated on the Unit 2 containment High Pressure signal, Venting of the Unit 1 primary containment was commenced. At 2005 CDT, Unit 1 primary containment pressure reached the Group 2 primary containment isolation system setpoint (1.77 PSIG) causing the primary containment vent and purge valves being used to vent the Unit 1 containment to isolate. Unit 1 primary containment venting was being performed through the Standby Gas Treatment system which is a filtered system. In addition to the primary containment isolation signal on high drywell pressure, an ECCS initiation on high drywell pressure also occurred. The ECCS signal resulted in an auto start of the 1C RHR system. The 1B RHR system was already running in suppression pool cooling mode. 1A RHR and LPCS had been secured to prevent overloading the common diesel generator for division 1. The common diesel generator supplies both Unit 1 and Unit 2 division 1 ESF busses. The licensee informed the NRC Resident Inspector. Notified NRR EO (Skeen), IRD MOC (Grant) and R3IRC (Louden).
LaSalle has terminated the unusual event which was initiated at 1511 on 4/17/13 and reported under EN 48939. This unusual event has been terminated based on meeting the following established criteria. This report is being made in accordance with 10CFR50.72.(c)(1)(iii). 1) Off-site power has been restored to all ESF busses 2) Fuel Pool Cooling has been restored on both units 3) Primary Containment Chillers have been restored on both units 4) Drywell pressure is less than ECCS initiation setpoint 5) ECCS signals cleared to allow diesels to be placed in stand by Recovery of remaining plant systems will be managed through the Outage Control Center (OCC)." The licensee informed the NRC Resident Inspector. Notified R3DO (Orth), NRR EO (Chernoff), IRD (Grant), DHS, FEMA, USDA, HHS, DOE, NICC, EPA, and Nuclear SSA via email.
In addition to the 10 CFR 50.72 Sections initially identified, the Loss of Offsite Power was also reportable under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of systems needed mitigate the consequences of an accident. This event is considered a safety system functional failure for both Units 1 and 2. The licensee will notify the NRC Resident Inspector. Notified the R3DO (Orth). | Primary Containment Isolation System Reactor Core Isolation Cooling Primary containment High Pressure Core Spray Core Spray Residual Heat Removal Standby Gas Treatment System Safety Relief Valve | 05000373/LER-2013-002 |
| ENS 42348 | 20 February 2006 06:23:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Site Area Emergency - Reactor Scram | While shutting down Unit 1 IAW LGP-2-1 with the main turbine off line the plant experienced a turbine control system (EHC) malfunction. This resulted in opening all main turbine bypass valves and subsequent reactor low pressure condition. The low pressure condition resulted in a closure of all main steam isolation valves (MSIV's) and automatic reactor scram. Three rods failed to indicate fully inserted on the scram. Plant emergency operating procedures were entered. All ECCS and plant systems operated as expected. All control rods are fully inserted and the ATWS emergency operating procedure has been exited. The main turbine had been taken off line prior to this event and shutdown was being conducted with heat removal on the bypass valves. Pressure control is currently by using the steam line drains with the Safety Relief Valves in manual. Level is being maintained using normal feedwater. The electrical grid is stable though the plant is not yet on backfeed. Diesel generators are operable. The licensee will notify the NRC Resident Inspector. The NRC entered Monitoring Mode at 0243. Notified R4DO (Graves), DHS (SWO), FEMA (J Kanupp), DOE (S. Morrone), EPA(NRC) (Nowak), USDA (Amanda), HHS (Kleiman).
In addition to the initial notification, La Salle is reporting a group 1 isolation in accordance with 10CFR50.72(b)(3)(iv)(a).
The site exited the Site Area Emergency and entered the recovery phase.
At the time of the scram @ 0023 hours rod 38-43 showed position 24 and rods 26-15 and 34-47 showed unknown. Based on more than one rod out condition, it is unanalyzed until shutdown margin can be verified.
NRC exited Monitoring Mode. Notified IRD (Wilson), NRR EO (J. Lyons), R3DO (Lara), R4DO (Graves), NRR (Dyer), DHS (SWO), FEMA (Eerwin), DOE (Joe Stambaugh), NRC (does not take updates), USDA (Jim Brzostek), HHS (SOC) (Lt Hrynyshen).
Post trip evaluations have confirmed that all control rods were fully inserted within four minutes of the reactor scram. A review of the post-trip data suggests that there were only control rod indication problems on the three subject rods and all control rods were fully inserted immediately at the time of the reactor scram. Follow-up evaluations also demonstrated that even if the three subject control rods remained fully withdrawn in a cold shutdown condition, the reactor would have remained adequately shutdown. Additional confirmatory evaluations are continuing. The licensee issued a press release on this event. The licensee notified the NRC Resident Inspector. R3DO(Hills) has been notified. | Feedwater Main Steam Isolation Valve Main Turbine Safety Relief Valve Control Rod | 05000373/LER-2006-001 |
| ENS 40845 | 28 June 2004 06:21:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Earthquake Registered on Site Seismic Monitors | At 0111, received a Strong Motion Seismic Alarm and received calls from numerous personnel onsite and offsite that they felt ground motion. A GSEP Unusual Event was declared at 01:21 due to a confirmed seismic event Emergency Action Level HU-4. A walk down of various plant areas including the Dike is in progress to determine if any equipment was affected or damaged. During the event, some spurious alarms were received which cleared with exception of the seismic alarm. The seismic alarm will be reset after Station Engineering reviews the seismic data. They observed a 1" water level spike that immediately returned to normal on main control room suppression pool water level recorder and plant process computer. At this time we have received no reports of equipment damage and walk downs are continuing. The earthquake measured 4.5 on the Richter Scale and was approximately 10 miles north of Ottawa, IL. Ottawa is located 10 miles NW of the site. Both Units remained on line and stable. The NRC Resident Inspector will be notified and the state was notified. NOTE: See related events 40844 and 40846.
This is an update to Event Number 40845. At 0355 CDT the Unusual Event, entered due to confirmed seismic event, was terminated. A walk down of various plant areas has been completed. No equipment damage was identified. The NARS (Nuclear Accident Reporting System) notification for termination was completed at 0405. The licensee notified the NRC Resident Inspector, the State and local authorities. Notified by e-mail: Susan Frant (IRO), Thomas Kozak (R3 DO), Frank Gillespie (NRR EO), Pat Hiland (Reg3), and Geoffrey Grant (R3). Also notified FEMA (Erwin Casto) and DHS (Andy Akers). |