ENS 42479
ENS Event | |
|---|---|
23:55 Apr 5, 2006 | |
| Title | Abnormal Operating Procedure (Aop) for Station Blackout Could Not Be Performed in Specified Time Period |
| Event Description | DAEC (Duane Arnold Energy Center) abnormal operating procedure AOP 301.1 for Station Blackout specifies that 30 minutes are allowed to establish alternate ventilation for RCIC (Reactor Core Isolation Cooling) /HPCI (High Pressure Coolant Injection) rooms, switchgear rooms, battery rooms, and the Main control room. During validation demonstration conducted on April 5, 2006 for the NRC Components team (from NRC Region 3 Office) the 30 minutes requirement was not met with the control room alternate ventilation taking about 60 minutes and with the other areas also exceeding their time requirements. This event is reportable as an unanalyzed condition that significantly degraded plant safety pursuant to 10 CFR 50.72(b)(3)(ii) reportability notification.
The NRC Resident Inspector was notified of this event by the licensee.
Duane Arnold Energy Center is retracting event number 42479 which was reported to the NRC Operations Center on 4/5/06 at 1855. This event is now determined to be not reportable because further evaluation to assess the significance of the delays in establishing alternate control room ventilation determined that the delay did not result in an adverse temperature increase in the affected areas. Specifically, the control room and back panel area temperature rise was evaluated using a detailed mass and heat transfer model of the affected areas. The evaluation confirmed that delays in establishing alternate control room ventilation did not adversely impact station commitments to 10 CFR 50.63 or accident responses outlined in UFSAR Section 15.3.2. Other areas required to have alternate ventilation established within 30 minutes had previously been successfully validated. Therefore, this event is not reportable as an unanalyzed condition that significantly degraded plant safety. The analyses and the bases for this retraction can be found under the plant corrective action program. The licensee notified the NRC Resident Inspector. R3DO (Kozak) notified. |
| Where | |
|---|---|
Duane Arnold  Iowa (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-2.53 h-0.105 days <br />-0.0151 weeks <br />-0.00347 months <br />) | |
| Opened: | W. Bentley 21:23 Apr 5, 2006 |
| NRC Officer: | John Mackinnon |
| Last Updated: | Jun 1, 2006 |
| 42479 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (96 %) |
| After | Power Operation (96 %) |
WEEKMONTHYEARENS 509432015-03-31T20:09:00031 March 2015 20:09:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Degraded Torus Coating ENS 424792006-04-05T23:55:0005 April 2006 23:55:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Abnormal Operating Procedure (Aop) for Station Blackout Could Not Be Performed in Specified Time Period ENS 420882005-10-27T18:28:00027 October 2005 18:28:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 417422005-06-02T23:49:0002 June 2005 23:49:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Appendix R Assessment on Remote Shutdown Panel 2015-03-31T20:09:00 | |