ENS 42737
ENS Event | |
|---|---|
09:19 Jun 4, 2006 | |
| Title | Invalid Rps Bus 'B' and Division 2 Pcis Actuations |
| Event Description | This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation reportable under 10 CFR 50.73(a)(2)(iv)(A).
On June 4, 2006, at 0419 [CST], with Unit 1 in Mode 1 'Run' at approximately 100% power, the 1B Reactor Protection System (RPS) bus unexpectedly de-energized. As a result, an RPS Bus B half-scram and Division 2 Primary Containment Isolation System (PCIS) isolations were received. All affected containment isolation valves closed as designed. RPS Bus B was transferred to its alternate feed, and restoration activities were begun. A walkdown found that the 1B RPS MG set output breaker had opened. Troubleshooting identified that the cause was a failure of the 1B RPS MG set voltage regulator. The voltage regulator was replaced and successfully tested, and the 1B RPS MG set was returned to service. Laboratory testing of the failed voltage regulator found that the stability potentiometer had failed, with excessive vibration identified as the apparent cause. Although the vibration levels at the MG set are considered to be normal, the voltage regulator is mounted in a control cabinet that sits directly on the generator end of the MG set. The normal vertical vibration on the 1B MG set was measured at greater than 2g, which could be sufficient over time to degrade the voltage regulator potentiometers. A design change has been initiated for both Units to isolate the voltage regulators from the RPS MG set vibrations. This event is reportable under 10 CFR 50.73(a)(2)(iv)(A) as an invalid actuation of containment isolation valves in more than one system. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Lasalle  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1283.68 h53.487 days <br />7.641 weeks <br />1.758 months <br />) | |
| Opened: | Jeff Williams 21:00 Jul 27, 2006 |
| NRC Officer: | Mike Ripley |
| Last Updated: | Jul 27, 2006 |
| 42737 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 552402021-03-10T13:15:00010 March 2021 13:15:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of an Invalid Specified System Actuation ENS 530832017-10-06T14:10:0006 October 2017 14:10:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation ENS 522272016-07-11T09:30:00011 July 2016 09:30:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Division 1 Primary Containment Isolation Logic Due to a Blown Fuse ENS 491742013-05-22T16:34:00022 May 2013 16:34:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Telephonic Notification of Invalid Division 1 Containment Isolation Due to Motor Generator Trip ENS 462202010-07-26T23:19:00026 July 2010 23:19:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephonic Notification in Lieu of a Written Licensee Event Report of Invalid Actuation ENS 458782010-03-05T10:39:0005 March 2010 10:39:00 10 CFR 50.73(a)(1), Submit an LER Invalid Isolation Signal Caused Msiv'S to Close ENS 433582007-03-15T06:02:00015 March 2007 06:02:00 10 CFR 50.73(a)(1), Submit an LER Invalid Eccs and System Actuations ENS 433332007-03-03T13:14:0003 March 2007 13:14:00 10 CFR 50.73(a)(1), Submit an LER Invalid Eccs Actuation During Refueling Outage ENS 427372006-06-04T09:19:0004 June 2006 09:19:00 10 CFR 50.73(a)(1), Submit an LER Invalid Rps Bus 'B' and Division 2 Pcis Actuations ENS 425262006-03-04T10:12:0004 March 2006 10:12:00 10 CFR 50.73(a)(1), Submit an LER Invalid Emergency Diesel Generator Start ENS 415602005-02-07T13:56:0007 February 2005 13:56:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation 2021-03-10T13:15:00 | |