ENS 46771
ENS Event | |
|---|---|
14:15 Apr 20, 2011 | |
| Title | Watertight Doors Left Ajar Simultaneously During Room Checks |
| Event Description | During the performance of operator rounds in the Lake Screenhouse Safe Shutdown System (SX) pump rooms, two water tight doors were left opened simultaneously during the room checks. These two doors opened simultaneously [which] allowed for communication between the Division 1 SX room and Division 2 SX pump room. The operator was in constant attendance in the Division 2 SX pump room during the performance of the equipment checks.
During site review, it was determined that a flood in either the Division 1 or Division 2 SX pump rooms would not be isolated to the initiating room, but potentially affect both trains of SX. This could result in a loss of cooling for both Residual Heat Removal systems, therefore, a condition that could have prevented fulfillment of a safety function under 10CFR50.72(b)(3)(v)(B). The NRC Senior Resident has been notified. Offsite power is normal and emergency diesel generators are operable and available.
A subsequent plant barrier impairment evaluation consistent with Exelon Procedure CC-AA-201, 'Plant Barrier Control Program' has determined that no loss of safety funct ion would have occurred. Each of the following door functions and related postulated events were reviewed for impact: ventilation; flooding, internal and external; high energy line breaks; missiles; radiation protection; and fires. For the condition with the SX pump room water tight doors being open with an operator in the area, the conclusion is an SX division remains protected to ensure that in any of the evaluated events the safety function of SX has been maintained. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Clinton  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+3.83 h0.16 days <br />0.0228 weeks <br />0.00525 months <br />) | |
| Opened: | Ed Tiedemann 18:05 Apr 20, 2011 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Jun 8, 2011 |
| 46771 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (97 %) |
| After | Power Operation (97 %) |
WEEKMONTHYEARENS 482692012-09-03T03:04:0003 September 2012 03:04:00
[Table view]10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Transfer of Emergency Reserve Auxiliary Transformer Isolating Fuel Pool Cooling and Cleanup System, and Fuel Building Ventilation System ENS 475332011-12-18T15:30:00018 December 2011 15:30:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Rhr Cooling Due to Incorrect Reactor Water Level Indication ENS 467712011-04-20T14:15:00020 April 2011 14:15:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Watertight Doors Left Ajar Simultaneously During Room Checks ENS 421612005-11-21T16:42:00021 November 2005 16:42:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Division 3 Emergency Diesel Generator Declared Inoperable 2012-09-03T03:04:00 | |