ENS 46827
ENS Event | |
|---|---|
17:00 May 6, 2011 | |
| Title | Changes in Fuel Vendor Calculation Methodology to Comply with the Eccs Performance Requirements of 10 Cfr 50.46(B) |
| Event Description | Nine Mile Point Nuclear Station Unit 1 has been informed of a change in its fuel vendor's (General Electric Hitachi) Calculation of the Peak Cladding Temperature (PCT) and Maximum Local Oxidation (MLO). This change was required to address four individual errors and model changes identified by the fuel vendor for the previous calculation of record. Based on 10 CFR 50.46 Appendix K inputs and assumptions, correction of one of the identified errors resulted in a calculated 60 degrees F increase in PCT and a calculated 4 percent increase in MLO, which results in exceeding the PCT and MLO acceptance criteria specified in 10 CFR 50.46 (b). In addition, corrections for two of the other identified items resulted in calculated MLO values that also exceeded the MLO acceptance criterion. However, the cumulative effect of all four of the identified errors/changes was determined to result in calculated PCT and MLO values that remain within the 10 CFR 50.46(b) acceptance criteria.
To ensure compliance with the 10 CFR 50.46 requirements, adjusted Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) limits have been implemented to maintain the PCT and MLO values within the 10 CFR 50,46(b) acceptance criteria and restore design margins. These changes were made prior to the Nine Mile Point Unit 1 startup from the recent spring 2011 refueling outage 21 through a plant monitoring system update. The updated MAPLHGR limits have also been included in the NMP1 Core Operating Limits Report (COLR) for the current operating cycle (Cycle 20), which commenced following the 2011 refueling outage. As such, Nine Mile Point Unit 1 Cycle 20 is in full compliance with the 10 CFR 50.46 requirements. This notification is being made in accordance with the 10 CFR 50.46(a)(3)(ii) requirement to report this issue in accordance with 10 CFR 50.72 and 10 CFR 50.73. Based on current core thermal power level and existing margin to limits on power operation, there is sufficient margin for analyzed accident scenarios requiring Emergency Core Cooling System (ECCS) operation, including appropriate MAPLHGR compensation, to maintain the calculated PCT and the MLO within the 10 CFR 50.46 acceptance criteria; therefore, there is no impact on safe operation of the plant. The current LOCA analysis of record remains applicable and therefore, the calculated radiological consequences are still bounded by our current safety analysis. Therefore, this event is not significant with respect to the health and safety of the public. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Nine Mile Point  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-0.23 h-0.00958 days <br />-0.00137 weeks <br />-3.15054e-4 months <br />) | |
| Opened: | Christine Jones 16:46 May 6, 2011 |
| NRC Officer: | Pete Snyder |
| Last Updated: | May 6, 2011 |
| 46827 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 500982014-05-08T20:45:0008 May 2014 20:45:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 494642013-10-22T18:00:00022 October 2013 18:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 468272011-05-06T17:00:0006 May 2011 17:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Changes in Fuel Vendor Calculation Methodology to Comply with the Eccs Performance Requirements of 10 Cfr 50.46(B) ENS 439902008-02-16T00:02:00016 February 2008 00:02:00 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 Potential Inoperability of Emergency Core Cooling Systems Due to an Unalalyzed Condition ENS 407492004-05-14T13:17:00014 May 2004 13:17:00 Other Unspec Reqmnt, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Change in the Methodology Used by Ge/Gnf to Demonstrate Compliance with Eccs Performance Requirements 2014-05-08T20:45:00 | |