ENS 41379
ENS Event | |
|---|---|
05:19 Feb 7, 2005 | |
| Title | Emergency Diesel Start Due to Bus Deenergization |
| Event Description | The following information was provided by the licensee via facsimile:
The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. On February 6, 2005, at approximately 22:19 Mountain Standard Time (MST) a valid actuation of the Palo Verde Nuclear Generating Station Unit 1 Train `B' Emergency Diesel Generator (EDG) occurred as a result of undervoltage on its respective safety bus (PBB-S04). EDG 'B' started and loaded as designed to energize PBB-S04. The loss of power to the safety bus was the result of a fault associated with 13.8KV breaker NAN-SO6J which caused breakers NAN-SO6H (normal power supply), NAN-S06K (alternate power supply), and NAN-SO6J (EOF & TSC Bldg power supply) to all trip open on Overcurrent. This action resulted in the deenergization of NAN-S06, NAN-S04, and PBB-S04. The PVNGS Fire Department and Auxiliary Operators responded to a report of smoke and upon arrival found no fire. The Fire Department verified the fire was completely extinguished and there were no extensions (secondary fires). Unit 1 entered Technical Specification LCO 3.8.1, Condition 'A', for one (of two) required offsite circuits inoperable. Various other Technical Specifications LCO's were momentarily entered and exited for PBB-S04 being deenergized for approximately 7 seconds. No Emergency Plan declaration was made and none was required. Unit 1 was at approximately 100% power, at normal operating temperature and pressure prior to and following the EDG actuation. No other ESF actuations occurred and none were required. No major equipment was inoperable prior to the event that contributed to the event. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant or the health and safety of the public. The NRC Resident Inspector has been notified of the ESF actuation and this ENS notification. The B EDG is providing power to PBB-S04. Due to loss of power to the TSC, the TSC Diesel started and is providing power to the TSC. The Backup EOF located in Buckeye, AZ will be used in the case of an emergency event. There were no reported injuries. There was damage to the NAN-S06J breaker and it has been isolated. The event has been entered into the site's corrective action program for determining the cause of the breaker trip and damage. This event has no effect on the operation of the other site units. |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000528/LER-2005-001 |
| Time - Person (Reporting Time:+-0.63 h-0.0263 days <br />-0.00375 weeks <br />-8.62974e-4 months <br />) | |
| Opened: | Steve Smith 04:41 Feb 7, 2005 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Feb 7, 2005 |
| 41379 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 570472024-03-24T23:34:00024 March 2024 23:34:00
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