ENS 55827
ENS Event | |
|---|---|
04:00 Feb 7, 2022 | |
| Title | Part 21 - CURTISS-WRIGHT Actuator Brake Wiring Deficency Report |
| Event Description | The following information was provided by Curtiss-Wright Nuclear Division via fax:
The Tennessee Valley Authority (TVA) Browns Ferry Plant notified us (QualTech NP, Curtiss-Wright Nuclear Division) of two separate RCS/Dresser actuator failures which we had provided as safety related components. According to TVA, the first failure occurred on February 7, 2022, after being installed for approximately 167 days. The 2nd failure occurred on February 9, 2022, and was in service for approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when it failed. According to TVA in both cases the actuator's brake assembly wire harness shorted out to the frame, causing the on-board fuse to blow, disabling the actuator. The electrical short was caused by the wire harness laying against a sharp edge of the metal frame, which over time led to fraying of the wire insulation and subsequent bare wire to frame contact. Both units were returned to QualTech NP for evaluation and our findings confirmed TVA's assessment. The root cause of the issue is friction between the wires and the sharp metallic edge that over time cut through the insulation via vibration, which in turn shorted the power leads to the frame. This shorting effect was due to poor positioning and restraint of the wire harness/bundle by the manufacturer during assembly. It is not considered a design flaw, but a workmanship issue caused by the factory assembler. The corrective action taken with the two units was to install new brake assemblies and reposition the wire harness to prevent contact with the sharp edge. In addition, wire ties were added to restrain the wire's movement and keep it away from the sharp edge. As a follow up action, the associated dedication plan will be revised to inspect for this workmanship issue and correct as needed. Additional details are provided in the failure evaluation. QualTech NP has only sold this part to TVA (Browns Ferry) and could not find any additional failures of this type reported by the industry. Identification of the customer's orders and hardware involved are provided in the evaluation. Please phone (513) 528-7900 if you should have any questions. |
| Where | |
|---|---|
| Tennessee Valley Authority Cincinnati, Ohio (NRC Region 3) | |
| Organization: | Curtiss Wright Flow Control Co. |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+1428.25 h59.51 days <br />8.501 weeks <br />1.956 months <br />) | |
| Opened: | Margie Hover 15:15 Apr 7, 2022 |
| NRC Officer: | Brian Lin |
| Last Updated: | Apr 7, 2022 |
| 55827 - NRC Website
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Tennessee Valley Authority with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
WEEKMONTHYEARENS 558272022-02-07T04:00:0007 February 2022 04:00:00
[Table view]10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 - CURTISS-WRIGHT Actuator Brake Wiring Deficency Report 2022-02-07T04:00:00 | |