ENS 50640
ENS Event | |
|---|---|
17:12 Nov 25, 2014 | |
| Title | Deficiency in Methodology Used for Emergency Core Cooling System Performance Requirements |
| Event Description | On Tuesday, November 25, 2014, at 1212 EST, Duke Energy Carolinas, LLC (Duke Energy) reviewed AREVA 10CFR50.46 Notification Letter FAB 14-00631. This letter indicates that a deficiency was discovered in the uranium thermal conductivity models used in the Oconee Nuclear Station Loss of Coolant Accident (LOCA) analysis of record. When the deficiency is corrected, the LOCA Peak Cladding Temperature (PCT) limits may be in excess of 2200 degrees F. 10CFR50.46 paragraph (b) defines the acceptance criteria for the LOCA analysis process. The Oconee licensing basis PCT is evaluated for compliance with the criterion 10CFR50.46(b)(1) and must not exceed a PCT of 2200 degrees F.
On October 20, 2014, AREVA recommended actions in the form of reductions in LOCA linear heat rates, which were then translated into reduced axial imbalance limits for the excore and backup incore detector systems. This was done to ensure that Duke Energy operated within 10CFR50.46 limits in the event of a loss of the full incore detector system. The full incore detector system is the primary method for evaluating imbalance and the imbalance limits are unaffected by the reduction in LOCA linear heat rates. The full incore detector system is operable and meets Technical Specification 3.2.2. In addition, the Reactor Protection System (RPS) trip limits for imbalance are not derived from the LOCA analysis and are not affected. When AREVA notified Duke Energy of the deficiency, Duke Energy confirmed that existing administrative limits bound the AREVA recommended actions and as a result, the errors reported have no impact on plant operation or public health and safety. This event affects all three (3) units and is being reported in accordance with 10CFR50.72(b)(3)(ii)(B). Based on 10CFR50.46(a)(3)(ii) criteria, Duke Energy will submit a written report within 30 days. Duke Energy has notified the NRC Senior Resident Inspector. |
| Where | |
|---|---|
Oconee  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000269/LER-2014-002 |
| Time - Person (Reporting Time:+-0.62 h-0.0258 days <br />-0.00369 weeks <br />-8.49276e-4 months <br />) | |
| Opened: | Jeremy Galloway 16:35 Nov 25, 2014 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Nov 25, 2014 |
| 50640 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 506402014-11-25T17:12:00025 November 2014 17:12:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Deficiency in Methodology Used for Emergency Core Cooling System Performance Requirements ENS 499682014-03-28T17:00:00028 March 2014 17:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Keowee Emergency Power System 13.8Kv Cable May Not Comply with Licensing Basis ENS 490682013-05-24T18:00:00024 May 2013 18:00:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 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, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Heating Ventilation and Air Condition System Inadequately Analyzed for Heat Load ENS 478102012-04-06T02:38:0006 April 2012 02:38:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Standby Shutdown Facility (Ssf) Not Analyzed for All Operating Conditions ENS 423182006-02-07T01:50:0007 February 2006 01:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Non-Conforming Fire Barriers ENS 418502005-07-18T15:30:00018 July 2005 15:30:00 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 Electrical Alignment Results in Single Failure Vulnerability ENS 417282005-05-24T17:50:00024 May 2005 17:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Involving Emergency Backup Power Generators ENS 407242004-05-04T20:55:0004 May 2004 20:55:00 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 Unanalyzed Condition and Potential Loss of Containment Safety Function ENS 401922003-09-23T08:00:00023 September 2003 08:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Potential Rcs Leakage at Oconee 1 2014-03-28T17:00:00 | |