ENS 47063
ENS Event | |
|---|---|
04:00 Jul 15, 2011 | |
| Title | Potential Defect in Qualtech Np Safety Related Motor Control Center Buckets |
| Event Description | The following information was received via facsimile from QualTech NP:
This letter is issued to provide initial notification of a potential defect in QualTech NP safety related MCC [Motor Control Center] buckets, which were commercial grade dedicated at our Cincinnati facility. On June 9, 2011, TVA Watts Bar Unit 2 notified QualTech NP of a failure on a transformer module associated with an indicator light on the MCC bucket. Based on our investigations, QualTech NP has identified quality and performance issues relating to the 480 VAC input (primary side) portion of the subject indicating light. The light in question has shown the potential to flash/arc internally on the primary winding side of the built in transformer and create a substantial fault current. This fault current not only disables the light but can be large enough to trip the upstream circuit breaker, thus disabling all associated safety related circuitry. The issues appear to revolve around inconsistent and poor quality fabrication methods employed during manufacturing, primarily with how the wires were wrapped in critical areas of the primary and how they were routed and attached to the termination points. The recommended corrective action for existing safety related MCC buckets is to replace the indicator light and transformer module with a newly qualified acceptable substitute. The new indicator light and transformer module will go through a series of dedication inspections and tests to ensure that a similar failure does not occur. Based on review of our records, Tennessee Valley Authority is the only customer to have these defective modules.
QualTech NP conducted failure analyses to determine the root cause. Based on the results of our investigations, QualTech NP has determined that this failure represents a defect in a basic component as defined by 10CFR21. The failure analyses concluded that all of the failure modes encountered were due to manufacturing defects associated with the soldering and handling of the wire strands in the vicinity of the line terminals. QualTech NP has established a corrective action plan to replace all of these components known to be installed in safety-related applications. We are currently in the process of evaluating a suitable replacement. Based on review of our records, Tennessee Valley Authority is the only customer to have these defective modules. We have been in close communications with TVA on this issue. The specific component is Model Number 9001KP5R31, manufactured by Square D. R2DO (Desai) and the Part 21 Group notified. |
| Where | |
|---|---|
| Qualtech Np Cincinnati, Ohio (NRC Region 3) | |
| Organization: | Qualtech Np |
| Reporting | |
| 10 CFR 21.21 | |
| Time - Person (Reporting Time:+16.72 h0.697 days <br />0.0995 weeks <br />0.0229 months <br />) | |
| Opened: | Kurt Mitchell 20:43 Jul 15, 2011 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Aug 5, 2011 |
| 47063 - NRC Website | |
Qualtech Np with 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation | |
WEEKMONTHYEARENS 470632011-07-15T04:00:00015 July 2011 04:00:00
[Table view]10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation Potential Defect in Qualtech Np Safety Related Motor Control Center Buckets ENS 464012010-09-16T05:00:00016 September 2010 05:00:00 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation Part 21 Report - Ups Motherboard Failed Pre-Service Inspection 2011-07-15T04:00:00 | |