ENS 42129
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ENS Event | |
|---|---|
14:44 Nov 8, 2005 | |
| Title | Design Basis for Long Term Cooling Not Correctly Modeled |
| Event Description | While investigating an issue related to containment coatings and their potential to clog the containment sump strainers, errors were discovered in the calculations that were used as the basis for responding to GL98-04. The errors involved the improper application of a correlation that was used to derive head loss across a screen that was assessed to be partially fouled with debris and the incorrect application of the results to a partially submerged screen that would be susceptible to air intrusion. Further investigation revealed that the flow path for a partially blocked strainer was not correctly modeled for the containment sump strainer and containment sump valve (SI-850A&B). The SI-850 valves have a rising disk and are located inside and at the bottom of the containment sump strainer. These errors in the modeling fidelity potentially impact the analytical basis for demonstrating compliance with the acceptance criteria in 10 CFR 50.46 (b)(5), Long-term Cooling.
Immediate actions - Operability analyses were performed. These operability analyses demonstrated that adequate NPSH would be available to the ECCS pumps to ensure long-term cooling. Long-term action - The containment sump strainer will be modified, as committed to in Point Beach letter NRC 2005-0109, "Nuclear Management Company Response to Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors, for Point Beach Nuclear Plant," dated September 1, 2005. This modification will result in a larger strainer surface area and a greater clearance in the vicinity of the SI-850 valves. These modifications will be supported by design analysis and testing that will demonstrate the strainers comply with the long-term cooling capability requirement of 10 CFR 50.46 (b)(5). The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Point Beach  Wisconsin (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000266/LER-2005-006 |
| Time - Person (Reporting Time:+2.88 h0.12 days <br />0.0171 weeks <br />0.00395 months <br />) | |
| Opened: | Ryan Rode 17:37 Nov 8, 2005 |
| NRC Officer: | John Knoke |
| Last Updated: | Nov 8, 2005 |
| 42129 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 532392018-03-01T22:43:0001 March 2018 22:43:00
[Table view]10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Potential Tornado Missile Vulnerabilities ENS 529762017-09-18T22:24:00018 September 2017 22:24:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Control Room Envelope Not Maintained ENS 507402015-01-15T23:04:00015 January 2015 23:04:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Inadequately Sealed Piping Penetrations and Postulated Flooding Event ENS 484022012-10-12T09:20:00012 October 2012 09:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Reactor Power Exceeded Fsar Analyzed Value ENS 443512008-07-16T20:16:00016 July 2008 20:16:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Potential Fire Propagation Between Rooms Could Affect Appendix R Safe Shutdown ENS 434872007-07-12T15:15:00012 July 2007 15:15:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Fire Inspection Analysis of Pressurizer Porvs and Block Valves ENS 433532007-05-09T21:23:0009 May 2007 21:23:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Identified Non Compliant Fire Protection Manual Operator Actions ENS 421292005-11-08T14:44:0008 November 2005 14:44:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Design Basis for Long Term Cooling Not Correctly Modeled ENS 421092005-11-02T05:00:0002 November 2005 05:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Tech Spec Required Shutdown Due to Degradation of Containment Coatings ENS 420202005-09-27T15:00:00027 September 2005 15:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Faults Have Electrical Current in Excess of the Maximum Listed Interrupting Ratings. ENS 418562005-07-20T09:51:00020 July 2005 09:51:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Minimum Recirculation Valves Will Not Automatically Open in Local Operating Mode ENS 417582005-06-08T22:24:0008 June 2005 22:24:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Fire Organizational Plan No Longer Aligned with Safe Shutdown Analysis ENS 417542005-06-07T23:00:0007 June 2005 23:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Appendix R Safe Shutdown Strategy Deficiency 2018-03-01T22:43:00 | |
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