ENS 42454: Difference between revisions
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| event date = 03/30/2006 16:50 CST | | event date = 03/30/2006 16:50 CST | ||
| last update date = 05/22/2006 | | last update date = 05/22/2006 | ||
| title = Inadequate Operator Response Time | | title = Inadequate Operator Response Time for Component Cooling Water System Realignment During a Large Break Loca | ||
| event text = At 1650 on March 30, 2006, a concern was identified where the operators in the training simulator could not complete realignment of the component cooling water (CCW) flow to the residual heat removal (RHR) heat exchanger in a timely manner under certain accident scenarios. This could result in exceeding the maximum design temperature of the CCW system. In addition, assumptions made in the containment pressure and temperature analysis following a large break loss of coolant accident (LOCA) are non-conservative with respect to when CCW flow to the RHR heat exchangers is manually established in accordance with emergency operating procedures. | | event text = At 1650 on March 30, 2006, a concern was identified where the operators in the training simulator could not complete realignment of the component cooling water (CCW) flow to the residual heat removal (RHR) heat exchanger in a timely manner under certain accident scenarios. This could result in exceeding the maximum design temperature of the CCW system. In addition, assumptions made in the containment pressure and temperature analysis following a large break loss of coolant accident (LOCA) are non-conservative with respect to when CCW flow to the RHR heat exchangers is manually established in accordance with emergency operating procedures. | ||
Callaway plant FSAR indicates CCW system flow is manually aligned to the RHR heat exchangers prior to the recirculation phase of emergency core cooling system (ECCS). If the automatic transfer of the RHR pumps to cold leg recirculation, which happens at the Lo-Lo-1 level of the refueling water storage tank (RWST), occurs before CCW flow has been manually aligned to the RHR heat exchanger, containment sump water at temperatures up to 270F can be circulated through the RHR heat exchanger without CCW flow on the other side of the heat exchanger. The CCW side of the heat exchanger would contain stagnant water. This water can heat up quickly with no established flow and exceed the design rated temperature of the system. | Callaway plant FSAR indicates CCW system flow is manually aligned to the RHR heat exchangers prior to the recirculation phase of emergency core cooling system (ECCS). If the automatic transfer of the RHR pumps to cold leg recirculation, which happens at the Lo-Lo-1 level of the refueling water storage tank (RWST), occurs before CCW flow has been manually aligned to the RHR heat exchanger, containment sump water at temperatures up to 270F can be circulated through the RHR heat exchanger without CCW flow on the other side of the heat exchanger. The CCW side of the heat exchanger would contain stagnant water. This water can heat up quickly with no established flow and exceed the design rated temperature of the system. | ||
Latest revision as of 22:18, 1 March 2018
| Where | |
|---|---|
Callaway  Missouri (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:+-1.17 h-0.0488 days <br />-0.00696 weeks <br />-0.0016 months <br />) | |
| Opened: | John Dampf 21:40 Mar 30, 2006 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | May 22, 2006 |
| 42454 - NRC Website
| |
Callaway with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |