ENS 44278
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ENS Event | |
|---|---|
20:56 Apr 23, 2008 | |
| Title | 60-Day Optional Notification of Invalid Specified System Actuation |
| Event Description | On April 23, 2008, at 3:56 p.m. CDT, power was lost on the reactor protection system (RPS) bus 'B'. The plant was operating at 100 percent power at the time. The loss of RPS bus 'B' interrupted power to the containment isolation actuation circuitry. This caused the Division 2 containment isolation valves in various balance-of-plant systems to automatically close, as designed. Plant operators implemented recovery procedures to shift RPS 'B' 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 [generating] capacity was not interrupted by the containment isolation signal.
The investigation of this event did not conclusively determine the cause of the loss of RPS bus 'B'. At the time of the event, scheduled maintenance was in progress to replace a relay which had contacts in the RPS 'B' circuitry. It is postulated that during this work, the technician inadvertently contacted part of the relay case while re-terminating the wiring, causing a short-circuit which blew a fuse in the circuit. This caused the output breaker on the RPS 'B' motor-generator set to trip, which de-energized the bus. This event is being reported in accordance with 10CFR50.73(a)(2)(iv)(A) as an invalid actuation of the Division 2 containment isolation actuation system. The loss of RPS 'B' also caused a half-scram signal to be generated. 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:+1120.52 h46.688 days <br />6.67 weeks <br />1.535 months <br />) | |
| Opened: | David Young 13:27 Jun 9, 2008 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Jun 9, 2008 |
| 44278 - 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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