ENS 42348
ENS Event | |
|---|---|
06:23 Feb 20, 2006 | |
| Title | Site Area Emergency - Reactor Scram |
| Event Description | 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 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> 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 Follow-up evaluations also demonstrated that even if the three subject control rods remained fully withdrawn in a cold shutdown condition, the reactor would have remained adequately shutdown.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. |
| Where | |
|---|---|
Lasalle  Illinois (NRC Region 3) | |
| Reporting | |
| Emergency class: | Site Area Emergency |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000373/LER-2006-001 |
| Time - Person (Reporting Time:+-4.15 h-0.173 days <br />-0.0247 weeks <br />-0.00568 months <br />) | |
| Opened: | Dan Coveyou 02:14 Feb 20, 2006 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Feb 22, 2006 |
| 42348 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (6 %) |
| After | Hot Shutdown (0 %) |
LaSalle with 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 | |
WEEKMONTHYEARENS 570832024-04-20T12:04:00020 April 2024 12:04:00
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