ENS 44517
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ENS Event | |
|---|---|
00:30 Aug 1, 2008 | |
| Title | Invalid Actuation of Containment Isolation Valves Due to a Power Failure |
| Event Description | On July 31, 2008, at 7:30 p.m. CDT, power was lost on the reactor protection system (RPS) bus A. The plant was operating at 100 percent power at the time. The loss of RPS bus A interrupted power to the containment isolation actuation circuitry. This caused the Division 1 containment isolation valves in various balance-of-plant systems to automatically close, as designed. Plant operators implemented recovery procedures to shift RPS A to its alternate power supply, and restore the systems affected by the isolation to service. The containment isolation valves were confirmed to have actuated as required. Plant capacity was not interrupted by the containment isolation signal.
The normal power supply for each RPS bus is a dedicated motor-generator set. The output of that generator is routed to the bus via two Electrical Protection Assembly (EPA) breakers arranged in series. Each EPA breaker has an internal power supply supporting the various trip functions designed into the breaker. Troubleshooting activities determined that the power supply in the upstream EPA breaker between the motor-generator set and the A RPS bus had failed, causing the undervoltage function of that EPA to actuate. The cause of the failure of the power supply has not been determined. This event is being reported in accordance with 10CFR50.73(a)(1) and 10CFR50.73(a)(2)(iv)(A) as an invalid actuation of the division 1 containment isolation actuation system. The licensee 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:+1333.07 h55.545 days <br />7.935 weeks <br />1.826 months <br />) | |
| Opened: | Tim Schenk 13:34 Sep 25, 2008 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Sep 25, 2008 |
| 44517 - 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 | |
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