ENS Event | |
|---|---|
18:30 Apr 13, 2016 | |
| Title | |
| Event Description | At approximately 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> EDT on 4/13/2016, it was determined that the source document for the mass and energy release parameters used to determine the containment pressure and temperature response to a Main Steam Line Break (MSLB) does not adequately account for all possible single active failure scenarios in the steam or feedwater line isolation provisions. The source document addresses the active failure of the Main Feedwater Control valves to close in the faulted steam generator feed line, but not the failure of a feedwater bypass valves to close in the faulted steam generator feed line. An active failure of a feedwater regulating bypass valve whereby the valve fails to close will increase the secondary mass available for release to the containment structure. This can result in a higher peak containment pressure that could challenge the containment design pressure. This condition is only a concern when the feedwater regulating bypass valves are in the open position in modes 1, 2 or 3, and they fail to close on a engineered safeguards actuation signal. The feedwater regulating bypass valves are currently closed.
This determination is being reported as an unanalyzed condition in accordance with 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Robinson  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-0.55 h-0.0229 days <br />-0.00327 weeks <br />-7.5339e-4 months <br />) | |
| Opened: | Steve Hebler 17:57 Apr 13, 2016 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Apr 13, 2016 |
| 51864 - NRC Website
Loading map... | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 521742016-08-11T19:05:00011 August 2016 19:05:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Robinson Dam Tainter Gates Unanalyzed Condition ENS 518642016-04-13T18:30:00013 April 2016 18:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 507782015-01-29T00:57:00029 January 2015 00:57:00 Other Unspec Reqmnt, 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 Safety System Will Not Function as Required ENS 406172004-03-28T15:26:00028 March 2004 15:26:00 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 Both Trains of High Pressure Safety Injection Inoperable for 25 Minutes 2016-08-11T19:05:00 | |