ENS 47473
ENS Event | |
|---|---|
23:00 Nov 22, 2011 | |
| Title | Temporary Loss of Shutdown Cooling |
| Event Description | During walkdown of scheduled work it was discovered that HCV-335 (Shutdown Cooling Heat Exchanger Inlet Header Isolation Valve) would not be able to be manually positioned open due to a missing idler gear key.
Upon a loss of instrument air, HCV-335 would have failed closed, interrupting shutdown cooling flow with no ability to open HCV-335 manually. Alternate shutdown cooling pump and paths were available at the time of discovery. No loss of instrument air or interruption in shutdown cooling flow occurred while preparing to align alternate shutdown cooling. An 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> LCO under Technical Specification 2.8.1(3)2 was entered at 1700 CST. Alternate shutdown cooling was established on a containment spray pump as allowed by procedure. The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> LCO was exited at 2306 CST. A replacement idler key has been fabricated for HCV-335. The licensee notified the NRC Resident Inspector.
Additional analysis has determined that the shutdown cooling system was capable of performing its design safety functions during the time that the idler key was missing. Therefore this event is being retracted. The licensee notified the NRC Resident Inspector. Notified R4DO (Walker). |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+2.72 h0.113 days <br />0.0162 weeks <br />0.00373 months <br />) | |
| Opened: | Robert Kros 01:43 Nov 23, 2011 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Dec 16, 2011 |
| 47473 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Refueling Shutdown (0 %) |
| After | Refueling Shutdown (0 %) |