ENS 41878
ENS Event | |
|---|---|
21:05 Jun 3, 2005 | |
| Title | Half Scram on Voltage Regulator Failure |
| Event Description | On June 3, 2005 at approximately 1705, with the James A. FitzPatrick Nuclear Power Plant (JAF) operating at 100% reactor power, a failure of the 'A' Reactor Protection System (RPS) motor generator voltage regulator occurred, resulting in a loss of power to the 'A' RPS bus, a half scram and multiple system isolations. The voltage transient caused by Technical Specification required RPS testing revealed the voltage regulator failure. Appropriate actions were taken in accordance with Abnormal Operating Procedure (AOP)-59, Loss of RPS Bus. All equipment operated as designed as a result of the loss of power to the RPS bus.
At 1744, the 'A' RPS bus was placed on the alternate power supply and the half scram was reset. The Primary Containment Isolation System (PCIS) isolation signal was reset at 1805 and restoration of the various isolated systems commenced shortly thereafter. The reactor remained at 100% reactor power throughout the event and Limiting Conditions for Operation were entered for the affected equipment as required. The above event meets the reporting criteria of 10 CFR 50.73(a)(2)(iv)(a) since the loss of RPS bus resulted in general containment isolation signals affecting containment isolation valves in more than one system. The following systems or components isolated as a result of the loss of RPS bus: Reactor Water Cleanup, Reactor Building Ventilation, 'A' Containment Atmosphere Dilution, Torus Vent and Purge, Drywell Equipment and Floor Drain Sumps, 'A' Drywell Containment Atmospheric Monitors, Recirculation System Sample Line, Main Steam Line Drains, Residual Heat Removal drain valve to radwaste, Standby Gas Treatment (auto Initiated). Since the signal was invalid (the result of loss of power vs, an actual containment isolation condition), this event meets the criteria in 10 CFR 50.73(a)(1) for being reported as a 60 day telephone notification In lieu of a written LER. The event was entered into the corrective action program. The loss of the 'A' RPS bus was caused by the failure of a uni-junction transistor (UJT) in the voltage regulator of the 'A' RPS motor generator, which resulted in an overvoltage condition and resultant protective trip. The voltage regulator was replaced with a spare from stock with a UJT from a different manufacturer. Other corrective actions include changing manufacturer's of the UJT (the former vendor no longer makes this UJT), and replacing the 'B' motor generator and alternate power supply voltage regulators with ones having new UJTs. The licensee notified the NRC Resident Inspector and the state Public Service Commission. |
| Where | |
|---|---|
Fitzpatrick  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1309.27 h54.553 days <br />7.793 weeks <br />1.793 months <br />) | |
| Opened: | Tim Page 10:21 Jul 28, 2005 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jul 28, 2005 |
| 41878 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 526452017-01-31T19:25:00031 January 2017 19:25:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-Day Report Due to Invalid Eccs Actuation Signal ENS 514802015-08-23T16:42:00023 August 2015 16:42:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Primary Containment Isolation Signal ENS 491792013-05-10T05:41:00010 May 2013 05:41:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Telephonic Notification of Invalid Actuation of an Emergency Diesel Generator ENS 485812012-10-13T07:18:00013 October 2012 07:18:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Report- Invalid Specified System Actuation ENS 485522012-10-02T14:37:0002 October 2012 14:37:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation Signal of the Primary Containment Isolation Level Transmitter ENS 446742008-10-14T16:06:00014 October 2008 16:06:00 10 CFR 50.73(a)(1), Submit an LER Faulty Voltage Regulator Causes Half Scram ENS 446732008-09-25T07:41:00025 September 2008 07:41:00 10 CFR 50.73(a)(1), Submit an LER Loose Connection Causes Half Scram While Shutdown ENS 442962008-05-31T16:06:00031 May 2008 16:06:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Report Involving an Invalid Group II Primary Containment Isolation ENS 433322007-04-12T10:20:00012 April 2007 10:20:00 10 CFR 50.73(a)(1), Submit an LER Primary Containment Isolation Due to Loss of Rps Power Supply ENS 429672006-09-08T23:28:0008 September 2006 23:28:00 10 CFR 50.73(a)(1), Submit an LER Half Scram Signal Due to Equipment Failure ENS 418782005-06-03T21:05:0003 June 2005 21:05:00 10 CFR 50.73(a)(1), Submit an LER Half Scram on Voltage Regulator Failure ENS 415552005-02-14T12:18:00014 February 2005 12:18:00 10 CFR 50.73(a)(1), Submit an LER Inadvertant Safety System Actuation During Maintenance ENS 412142004-10-08T01:55:0008 October 2004 01:55:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Report Due to an Invalid Actuation of Eccs and Edgs During Surveillance Activities ENS 411842004-10-07T07:44:0007 October 2004 07:44:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation 2017-01-31T19:25:00 | |