ENS 46368
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ENS Event | |
|---|---|
17:22 Oct 27, 2010 | |
| Title | Unit Commenced Shutdown After Declaring Containment Spray Inoperable |
| Event Description | During pressure drop testing of the backup nitrogen supply for HCV-345 (Containment Spray Header isolation valve) the accumulator failed its test. This renders HCV-345 inoperable. HCV-344 the opposite header isolation valve also has an air leak that appears to be of similar magnitude to the leak on HCV-345. Fort Calhoun Station is conservatively considering both valves inoperable and has entered technical specification 2.0.1 which requires shutting the plant down to hot standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. The plant shutdown began at 1513 CDT. Repair efforts are underway on HCV-345 and HCV-344.
The leakage on both valves was identified by systems engineering during testing. The licensee informed the NRC Resident Inspector.
At 1647 CDT, the licensee exited technical specification 2.0.1 after declaring HCV-344 operable. The Unit is currently at 74% power. The licensee will stabilize power at 70% and then commence power escalation. The licensee informed the NRC Resident Inspector. Notified R4DO (Proulx).
Following the original notification, the Fort Calhoun Station reviewed and reanalyzed the acceptance criteria for the subject valve air accumulators. The analysis determined that the valves had been and were operable during the event. Therefore, the report under 10CFR50.72(b)(3)(v)(D) is being retracted. The licensee has notified the NRC Resident Inspector. Notified R4D0 (Howell). |
| Where | |
|---|---|
| Fort Calhoun Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-0.28 h-0.0117 days <br />-0.00167 weeks <br />-3.83544e-4 months <br />) | |
| Opened: | Aaron Chladil 17:05 Oct 27, 2010 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Dec 17, 2010 |
| 46368 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (81 %) |
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