ENS 44138
ENS Event | |
|---|---|
17:45 Apr 14, 2008 | |
| Title | High Energy Line Break Analysis Revealed Potential Accident Mitigation Deficiency |
| Event Description | During review of a High Energy Line Break (HELB) analysis a condition was discovered where a break in the auxiliary steam system could result in a loss of all the containment fans and coolers, which are required to be maintained operable due to procedural restrictions to mitigate a design basis accident.
The plant entered Technical Specification (T.S.) 2.0.1 at 1245 CDT. This specification requires a plant shutdown within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Operations personnel isolated auxiliary steam to the affected areas of the Auxiliary Building at 1305 CDT. With auxiliary steam isolated to the Auxiliary Building, containment fans and associated coolers were restored to an operable status. Plant exited T.S. 2.0.1 at 1305 CDT. The licensee notified the NRC Resident Inspector.
An exhaustive review of the high energy line break licensing and design basis for the auxiliary steam system as it impacts the safety functions or the containment coolers has determined that the required safety functions are met for the licensed and designed basis of the plant. Therefore the previous notification (EN 44138) of April 14 is being withdrawn. The licensee notified the NRC Resident Inspector. R4DO (Pick) notified. |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-1.67 h-0.0696 days <br />-0.00994 weeks <br />-0.00229 months <br />) | |
| Opened: | Erick Matzke 16:05 Apr 14, 2008 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | May 5, 2008 |
| 44138 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |