ENS 42947
ENS Event | |
|---|---|
14:48 Oct 30, 2006 | |
| Title | |
| Event Description | During power operation, at 92% rated power, an automatic reactor trip occurred. The reactor protection signal that caused the reactor trip was steam generator 'B' steam flow greater than feedwater flow coincident with low water level on steam generator 'B.' The cause of the plant transient that led to the reactor trip was a loss of Instrument Bus 1 (Red Channel). Instrument Bus 1 unexpectedly deenergized during the performance of maintenance on the inverter (BRA-111) that feeds Instrument Bus 1.
Following the reactor trip, the auxiliary feedwater pumps automatically started, as designed, due to a low level in the steam generators. After the trip, non-safety related 4160 Volt AC Bus 4 de-energized and secondary plant feedwater heater 15B relief valve lifted. The cause of the loss of Bus 4 and 158 feedwater heater relief lifting Is under Investigation. The plant is currently stable and in the hot shutdown (HSD) mode. Power was restored to Instrument Bus 1 at 1018. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) as any event or condition that results in actuation of the Reactor Protection System (RPS) when the reactor is critical because of the automatic reactor trip and under 10 CFR 50.72(b)(3)(iv)(A), any event or condition that results in valid actuation of any of the systems listed below because of the actions of the RPS and the automatic start of the AFW pumps. All control rods fully inserted. Decay heat is being removed by feeding the steam generators with AFW and steaming to the Condenser Dump. The licensee notified the NRC Resident Inspector.
Due to the loss of Bus 4, the running Circulating Water Pump was lost resulting in a loss of normal heat sink to the condenser. The standby Circulating Water Pump was started at 1002 CST and the condenser heat sink was restored. Until the condenser steam dump was restored, the plant was steaming through the steam generator PORVs (atmospheric steam dumps). There is no steam generator tube leakage. The licensee notified the NRC Resident Inspector. Notified R3DO (M. Phillips) |
| Where | |
|---|---|
Kewaunee  Wisconsin (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-2.87 h-0.12 days <br />-0.0171 weeks <br />-0.00393 months <br />) | |
| Opened: | Jerry Riste 11:56 Oct 30, 2006 |
| NRC Officer: | Bill Gott |
| Last Updated: | Oct 30, 2006 |
| 42947 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (92 %) |
| After | Hot Standby (0 %) |
Kewaunee with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 466662011-03-10T21:49:00010 March 2011 21:49:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Inadvertant Opening a Substation Breaker Causing Loss of Station Power ENS 454382009-10-15T17:04:00015 October 2009 17:04:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Momentary Loss of Shutdown Cooling with Autostart of Emergency Diesel Generator ENS 431962007-02-28T05:33:00028 February 2007 05:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip During the Performance of a Surveillance ENS 430962007-01-12T16:39:00012 January 2007 16:39:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip/Reactor Trip ENS 429832006-11-10T20:20:00010 November 2006 20:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip at Low Power ENS 429472006-10-30T14:48:00030 October 2006 14:48:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip ENS 425302006-04-27T01:49:00027 April 2006 01:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Failure of Rps Signal to Initiate Reactor Trip ENS 421732005-11-29T04:20:00029 November 2005 04:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Following Main Feed Pump Trip ENS 414252005-02-20T17:58:00020 February 2005 17:58:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Actuation on Steam Generator Low Level 2011-03-10T21:49:00 | |