ENS 43692
ENS Event | |
|---|---|
09:08 Oct 5, 2007 | |
| Title | Loss of Both Emergency Service Water Pumps |
| Event Description | On October 5, 2007, at approximately 0408, while attempting to open 480 VAC breaker 1B4234A/B for preplanned maintenance, a loss of bus 1B42 occurred. The preliminary cause of the bus trip was arcing of the bucket stabs/bus bars when opening the door to breaker 1B4234A/B. The arcing was a result of the breaker bucket inadvertently pulling away from the bus. At the time of this event, the 'A' Emergency Service Water (ESW) pump was out of service for preplanned maintenance. The loss of 1B42 resulted in a loss of the 'B' ESW pump. The 'A' ESW pump was subsequently returned to service at 0458 on October 5, 2007. Note that power was conservatively lowered approximately 4% at 0512. At the time of this power reduction, the plant was not in a Technical Specification that would require a plant shutdown.
In addition to the loss of the 'B' ESW pump, the loss of 1B42 resulted in invalid Group 1-5 isolations on the 'B' side of PCIS (not including Main Steam Line Isolation Valves). This event is reportable under 10 CFR 50.72(b)(3)(v), Any event or condition that alone at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (D) Mitigate the consequences of an accident. The licensee notified the NRC Resident Inspector." The licensee has not yet determined if this is a mechanical failure of the breaker or a human error. However, they are looking at OE associated with this issue.
The licensee provided the following information as an update: In addition to the ESW loss of safety function that occurred, it has been determined that from 0408 till approximately 0715 on 10/05/07, a loss of both onsite emergency AC power sources occurred. Specifically, at the time of the event, the 'A' Emergency Diesel Generator (EDG) was out of service for preplanned maintenance. When bus 1B42 was lost, this resulted in a loss of 'B' ESW. The loss of 'B' ESW resulted in the 'B' EDG being incapable of performing its safety function. Therefore, this is another example of an event or condition that could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident. The licensee informed the NRC Resident Inspector. Notified R3DO (Hills).
On 10/05/07, this event was reportable under 10 CFR 50.72(b)(3)(v), Any event or condition that alone at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (D) Mitigate the consequences of an accident due to the loss of both ESW pumps. Further reviews have determined that the 'A' ESW pump was available at the time of the event and therefore, this event is not reportable for a loss of the ESW safety function. This event is still reportable for a loss of the on-site emergency AC power safety function. The licensee notified the NRC Resident Inspector. Notified the R3DO (Lara). |
| Where | |
|---|---|
Duane Arnold  Iowa (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+2.37 h0.0988 days <br />0.0141 weeks <br />0.00325 months <br />) | |
| Opened: | Bob Murrell 11:30 Oct 5, 2007 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Dec 4, 2007 |
| 43692 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (96 %) |
Duane Arnold with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 528812017-08-01T14:34:0001 August 2017 14:34:00
[Table view]10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection Steam Supply Valve Failed to Reposition ENS 516972016-01-29T15:20:00029 January 2016 15:20:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Offsite Power Declared Inoperable Due to Lowering Generator Voltage ENS 510062015-04-23T15:50:00023 April 2015 15:50:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Safety Systems Declared Inoperable Due to Equipment Malfunction ENS 508912015-03-13T17:30:00013 March 2015 17:30:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Low Pressure Coolant Injection Declared Inoperable ENS 501542014-05-30T15:43:00030 May 2014 15:43:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection Pump Received an Invalid Isolation Signal ENS 495662013-11-21T08:29:00021 November 2013 08:29:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Diesel Generator Inoperability ENS 480642012-07-02T20:05:0002 July 2012 20:05:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Declared Inoperable ENS 475612011-12-30T02:09:00030 December 2011 02:09:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Lpci Instrumentation Required Repair and Recalibration ENS 466452011-02-26T15:48:00026 February 2011 15:48:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection System Inoperable ENS 450102009-04-23T00:45:00023 April 2009 00:45:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) System Declared Inoperable ENS 436922007-10-05T09:08:0005 October 2007 09:08:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Loss of Both Emergency Service Water Pumps ENS 436022007-08-27T05:00:00027 August 2007 05:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident One Channel of Low Main Steam Line Pressure Signal Mistakenly Removed from Service for 33 Minutes ENS 433312007-05-01T01:17:0001 May 2007 01:17:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Declared Inoperable Due to Primary Containment Nitrogen Leak ENS 432622007-03-28T18:41:00028 March 2007 18:41:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Inoperable Due to Surveillance Test Failure ENS 431612007-02-12T16:52:00012 February 2007 16:52:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Both Standby Filter Units Inoperable ENS 431182007-01-24T15:55:00024 January 2007 15:55:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Missing Pipe Clamp Bolt Found on High Pressure Coolant Injection (Hpci) System ENS 428352006-09-08T09:01:0008 September 2006 09:01:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Containment Atmospheric Dilution (Cad) System Inoperable ENS 420252005-09-29T20:34:00029 September 2005 20:34:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) Declared Inoperable 2017-08-01T14:34:00 | |