ENS 50774
ENS Event | |
|---|---|
16:12 Dec 6, 2014 | |
| Title | 60 Day Optional Report - Half Scram and a Division 2 Primary Containment Isolation Signal |
| Event Description | On December 6, 2014, at approximately 1012 CST, while the plant was operating at 100 percent power, the Division 2 reactor protection system (RPS) bus de-energized unexpectedly. This resulted in a half-scram and a Division 2 primary containment isolation signal. Operators executed the appropriate abnormal operating procedures to begin an orderly restoration of the affected systems. Atmospheric pressure in the primary containment momentarily reached the high-pressure alarm setpoint, necessitating entry into the emergency operating procedure for that condition.
Automatic isolation valves in the following systems closed as designed: - reactor plant component cooling water - drywell unit cooler water supply - reactor building floor and equipment drains - reactor building HVAC chilled water supply - containment airlock seal air supply - reactor recirculation system flow control valve hydraulics - main steam line drains - auxiliary building and annulus HVAC systems These engineered safety systems actuated as designed: - standby gas control filter trains - fuel building filter trains - control building filter trains The event occurred approximately 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> after the Division 2 RPS motor-generator (MG) was aligned to the bus following replacement of the voltage regulator. Following the event, the MG set was found running with its output breaker tripped. A failure analysis determined that the spike suppressor and the field flash card were potential sources of the MG breaker trip. The spike suppressor was replaced. Inspection of the field flash card found a strand of wire from one of the attached leads nearly touching a trace on the circuit board. Testing determined that the wire strand was the most likely cause for the breaker trip. With no spare card readily available, the wire strand was removed and the field flash card was re-installed. Other cards were inspected, and no similar conditions were found. The MG set was load tested for 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />, and was placed in service on December 17[, 2014]. Additionally, it is suspected that there is an intermittent failure occurring in the field flash card. A design change will be developed to correct that condition. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
River Bend  Louisiana (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1269.63 h52.901 days <br />7.557 weeks <br />1.739 months <br />) | |
| Opened: | Michael Branscum 13:50 Jan 28, 2015 |
| NRC Officer: | John Shoemaker |
| Last Updated: | Jan 28, 2015 |
| 50774 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 572062024-05-14T00:28:00014 May 2024 00:28:00
[Table view]10 CFR 50.73(a)(1), Submit an LER Invalid Partial Containment Isolation ENS 541212019-04-30T11:50:00030 April 2019 11:50:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification Due to Invalid Actuation of a General Containment Isolation Signal ENS 517842016-01-10T08:43:00010 January 2016 08:43:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of the Primary Containment Isolation Logic ENS 510032015-02-24T22:02:00024 February 2015 22:02:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephone Notification of Invalid System Actuation Due to Motor Generator Output Breaker Trip ENS 507742014-12-06T16:12:0006 December 2014 16:12:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Report - Half Scram and a Division 2 Primary Containment Isolation Signal ENS 468442011-03-20T12:24:00020 March 2011 12:24:00 10 CFR 50.73(a)(1), Submit an LER "a" Train Reactor Protection System Unexpectedly De-Energized Resulting in a Half Scram Signal ENS 445172008-08-01T00:30:0001 August 2008 00:30:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Containment Isolation Valves Due to a Power Failure ENS 443472008-06-02T11:24:0002 June 2008 11:24:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation of Division 1 Containment Isolation Valves ENS 442782008-04-23T20:56:00023 April 2008 20:56:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Notification of Invalid Specified System Actuation ENS 430122006-09-29T18:33:00029 September 2006 18:33:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specific System Actuation ENS 408472004-05-22T09:29:00022 May 2004 09:29:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Division 1 Primary Containment Isolation Due to Loss of a Rps Bus 2024-05-14T00:28:00 | |