ENS 44938
ENS Event | |
|---|---|
17:26 Mar 26, 2009 | |
| Title | Non-Functional Steam Exclusion Barrier |
| Event Description | This event was additionally reported under 10 CFR 50.72(b)(3)(v)(D), 'Mitigate the Consequences of an Accident.'
On 03/26/2009 at 1226 CDT, an engineering analysis determined that a steam exclusion door would not provide adequate steam exclusion protection. A metal plate, that had been installed over the door's glass window, would fail under the steam overpressure postulated during a high energy line break. The metal plate was replaced with one of a stronger design. Permanent repairs were completed on the door at 1549 on 03/26/2009. While the original plate was installed, the barrier was non-functional. In accordance with TRM 3.0.9, Section A.1 all equipment supported by that steam exclusion barrier was immediately declared inoperable. This zone includes both trains of ECCS and support equipment (i.e., SI, RHR, ICS, CCW, etc.). TS 3.0.c was entered and exited during the time the door issue was identified and repaired. All 3 trains of Auxiliary Feedwater were declared inoperable due to AFW low suction pressure trip channels were declared inoperable per TS 3.4.b.5. Power was reduced to less than 1673 MWt per TS 3.4.b.3. All mode changes were suspended per TS 3.4.b.2. Therefore, this is reportable under 10 CFR 50.72 (b)(3)(v), 'Any event or condition that at the time of discovery could have prevented the fulfillment of a safety function,' and under 10 CFR 50.72(b)(3)(ii)(B) 'any event or condition that results in the nuclear plant being in an unanalyzed condition that significantly degrades plant safety.' Containment Fan Coil Unit A was not operational during this event. The licensee notified the NRC Resident Inspector.
On March 26, 2009 EN 44938 provided notification that both trains of ESF equipment (e.g. SI, RHR, ICS, CCW, etc.) were inoperable based on an engineering analysis, which determined that a steam exclusion door in the auxiliary building would not provide adequate steam exclusion protection. Subsequent physical pressure testing of equivalent doors and engineering evaluation of the test results determined that the door remained capable of fulfilling its steam exclusion function. A series of pressure tests demonstrated that the door (including a metal plate that had been installed over the door's glass window) would withstand the steam overpressure postulated during a high energy line break. Therefore, the door remained functional and the supported ESF equipment in the auxiliary building remain operable. Consequently, this condition did not meet the reportability criteria in 10 CFR 50.72. As a result, the notification made on 3/26/09 is hereby retracted. This condition was also reported in Licensee Event Report (LER) 2009-005-00 on May 21, 2009." The licensee is planning on retracting this LER. |
| Where | |
|---|---|
Kewaunee  Wisconsin (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 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 | |
| Time - Person (Reporting Time:+2.28 h0.095 days <br />0.0136 weeks <br />0.00312 months <br />) | |
| Opened: | Gary Ahrens 19:43 Mar 26, 2009 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Sep 9, 2009 |
| 44938 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (94 %) |