ENS 46568
ENS Event | |
|---|---|
05:00 Jun 5, 2010 | |
| Title | Potential Part 21 - Bus Disconnect Stab Assembly - 600V Essential Motor Control Centers |
| Event Description | During 2004, 2006 and 2010, Duke Energy Corporation (Duke) ordered spare parts for the 600V Essential Auxiliary Power System (EPE) motor control center, installed at the McGuire and Catawba Nuclear Stations. The spare parts were ordered under Purchase Orders 15488, 38585, 132512 and 134626 from Electrical Power Systems, Inc. (EPSI). The specific part is a NEMA Size 1 stab (disconnect) assembly for connecting motor control center feeder circuits to the motor control center main bus. The McGuire and Catawba motor control centers were manufactured by Nelson Electric in Tulsa, OK. Spare stab assemblies were needed for QA-1 applications but they were no longer available to purchase from an approved vendor. The parts were evaluated and approved for Commercial Grade procurement.
When the stab assemblies were received they were dedicated on site at Duke for Commercial Grade application at McGuire and also at Catawba. Inspection of the parts and application of the commercial grade process did not identify that the parts were not manufactured to the specifications used in the commercial grade evaluation process. The manufacturer, who was different from the original parts manufacturer, had revised the detail drawing of the stab assembly. The revised drawing allowed a different method for soldering the lead wire to the stab. During parts dedication, the new stab assemblies passed basic electrical checks, but there was no visual inspection of the soldering because the connections had been inserted into the stab assembly molding. Catawba Unit 1 experienced a failure of the Jacket Water Keep Warm Pump Motor circuit for Diesel Generator (D/G) 1B on June 05, 2010 due to failure of the soldered connection on a stab assembly that had just been installed. The pump motor is QA Condition 1 and it is powered from a QA Condition 1 motor control center. The failure of the Catawba Unit 1 D/G Keep Warm Pump Motor was not significant from a plant risk standpoint. Of the 21 spare stab assemblies purchased and dedicated for use at Catawba and McGuire, only one was placed in service. That stab assembly was installed at Catawba on 6/3/2010 and failed on 6/5/2010. The remaining suspect stab assemblies at Catawba and McGuire were put on HOLD shortly after this failure. Other than the failed Catawba stab assembly, no other suspect stab assemblies were placed in service in the past or currently at McGuire or Catawba Nuclear Stations. None of these dedicated stab assemblies were sold or transferred to another nuclear utility. Following the failure of the stab assembly at Catawba, stab assemblies were tested, a failure investigation was performed, design information was requested from the vendor and the commercial grade program implications were investigated. It was not until January 2011 that the issue was determined to be reportable per 10 CFR Part 21. The licensee provided courtesy notifications to the North Carolina and South Carolina Warning Points and York, Gaston and Mecklenburg County agencies. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
| Electrical Power Systems York, South Carolina (NRC Region 1) | |
| Organization: | Catawba Nuclear Site |
| Reporting | |
| 10 CFR 21.21 | |
| Time - Person (Reporting Time:+5604.18 h233.508 days <br />33.358 weeks <br />7.677 months <br />) | |
| Opened: | Gary Burgess 18:11 Jan 24, 2011 |
| NRC Officer: | Vince Klco |
| Last Updated: | Jan 24, 2011 |
| 46568 - NRC Website | |
Electrical Power Systems with 10 CFR 21.21 | |
WEEKMONTHYEARENS 465682010-06-05T05:00:0005 June 2010 05:00:00
[Table view]10 CFR 21.21 Potential Part 21 - Bus Disconnect Stab Assembly - 600V Essential Motor Control Centers 2010-06-05T05:00:00 | |