ENS 46416
ENS Event | |
|---|---|
19:00 Nov 12, 2010 | |
| Title | Inaccurate Information Provided in License Amendment Request |
| Event Description | At 1300, on November 12, 2010, Exelon Generation Company LLC concluded that inaccurate information contained in the PRA technical bases for a 1987 License Amendment Request (LAR) for Byron and Braidwood Stations would have potentially impacted the acceptability of the LAR by the NRC. The LAR was to extend Allowed Outage Times (AOT) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days for several systems, to include the Component Cooling (CC) and Residual Heat Removal (RH) Systems.
The original design intent of the CC system was that each unit has two independent CC pumps and a fifth pump (U0) CC pump could be used as an operable spare for any of the unit specific pumps. This is how CC was modeled in the PRA technical justification for the 1987 LAR. However, a piping configuration design flaw was recently evaluated in that the U0 CC pump could not be considered an operable spare for either unit's B pumps was not modeled in the PRA. During the evaluation to assess the potential significance of this CC design flaw on the PRA justification for the 1987 LAR, another potentially significant discrepancy was discovered in that it appears the operational practice to always split CC trains after a design basis LOCA was not modeled correctly in the RH analysis. Administrative controls have been put in place to restrict the AOT for the CC pumps and RH trains to the pre-LAR timeframe of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> pending the permanent corrective actions. In addition, administrative controls have been put in place to prohibit the U0 CC pump from being an operable spare for either unit's B trains. This event is being reported as an unanalyzed condition that significantly degrades plant safety under 10 CFR 50.72(b)(3)(ii). The NRC Resident Inspectors have been notified |
| Where | |
|---|---|
Byron  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-2.45 h-0.102 days <br />-0.0146 weeks <br />-0.00336 months <br />) | |
| Opened: | Leo Wehner 16:33 Nov 12, 2010 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Nov 12, 2010 |
| 46416 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 519582016-05-25T18:00:00025 May 2016 18:00:00
[Table view]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 Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 517722016-03-07T10:00:0007 March 2016 10:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Involving Diesel Driven Auxiliary Feedwater Pump Air Intakes ENS 513352015-08-20T22:55:00020 August 2015 22:55:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Condition That Could Prevent Pressurizer Porv Block Valves from Operating ENS 467082011-03-30T01:00:00030 March 2011 01:00:00 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 Voiding in Auxiliary Feedwater Alternate Suction Line ENS 464162010-11-12T19:00:00012 November 2010 19:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Inaccurate Information Provided in License Amendment Request 2016-05-25T18:00:00 | |