ENS 50639
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ENS Event | |
|---|---|
17:00 Nov 25, 2014 | |
| Title | Non-Conservatisms in Methodology Used for Emergency Core Cooling System Performance Requirements |
| Event Description | On Tuesday, November 25, 2014, at 1200 EST, the FirstEnergy Nuclear Operating Company (FENOC) reviewed AREVA 10CFR50.46 Notification Letter FAB14-00625 for the Davis-Besse Nuclear Power Station (DBNPS). This letter indicates that certain non-conservatisms were discovered in the methodology application and inputs used by AREVA for nuclear fuel core configurations with Mark-B-HTP fuel when operated under certain conditions. When corrected, this increases the Peak Cladding Temperature (PCT) in excess of the value prescribed in 10CFR50.46(b)(1) under Loss of Coolant Accident (LOCA) conditions. The DBNPS reactor core contains Mark-B-HTP fuel. 10CFR50.46 paragraph (b) defines the acceptance criteria for the LOCA analysis process. The DBNPS licensing basis PCT is evaluated for compliance with and must not exceed the criterion prescribed in 10CFR50.46(b)(1).
AREVA had provided compensatory measures in terms of plant axial imbalance limits and Fq linear heat rate limits associated with reductions in LOCA linear heat rates so that the DBNPS operates within 50.46 limits. FENOC implemented the compensatory measures at the DBNPS on October 23, 2014, per AREVA recommendations, and as a result the errors reported have no impact on current plant operation or public health and safety. Preliminary analysis of past operating conditions indicate that the DBNPS did not exceed the 50.46(b)(1) criteria for PCT. This 8-hour notification is being reported in accordance with 10CFR50.72(b)(3)(ii)(B). Based on 50.46(a)(3)(ii) criteria, FENOC will submit a report within 30 days for the DBNPS. FENOC has notified the DBNPS NRC Senior Resident Inspector. |
| Where | |
|---|---|
Davis Besse  Ohio (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000346/LER-2014-004 |
| Time - Person (Reporting Time:+-0.47 h-0.0196 days <br />-0.0028 weeks <br />-6.43806e-4 months <br />) | |
| Opened: | Tom Phillips 16:32 Nov 25, 2014 |
| NRC Officer: | Daniel Mills |
| Last Updated: | Nov 25, 2014 |
| 50639 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 553212021-06-22T16:08:00022 June 2021 16:08:00
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