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| Entered date | Event description | |
|---|---|---|
| ENS 55827 | 7 April 2022 15:15:00 | 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 hours 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. |
| ENS 51611 | 18 December 2015 15:50:00 | EN Revision Text: POTENTIAL PART 21 INVOLVING A200 SERIES STARTERS The following is excerpted from a report submitted by QualTech NP, Nuclear Division, Curtiss-Wright Corporation: Pacific Gas and Electric (PG&E) reported to QTNP (QualTech NP) that they have had eight Cutler Hammer A200 series starter failures since September 15, 2008. The failures would remain in the operated/energized contact state with power removed for some period of time. All starters impacted with this failure were continuously energized. The concern was that if tripped, that the main contacts would not open to protect the motor. Testing was performed by Eaton Industrial Controls Division after receiving defective samples from PG&E. The test report from Eaton was received by QTNP for further review and evaluation. On October 6, 2015 QTNP determined that the Cutler Hammer A200 series starter failures may be reportable and an extent of condition review needed to be done. The root cause was a silicon based mold release that remained on the molded parts and would come between the moving (magnet) & fixed armatures. When heated for an extended period of time, this material would become sticky causing anywhere from a minor delay in opening, up to a frozen closed condition. Cutler Hammer has determined that the silicone mold release was first introduced into the manufacturing facility in May, 2008, due to a shortage of the Zinc Stearate Mold release that was traditionally used. The silicon based mold release was periodically used until October 2012. According to Cutler Hammer, anything made after January 1, 2013 should definitely be silicon mold release free. Thus any starters/contactors of the CH A200 series manufactured between May 2008 & December 31 , 2012 could have this concern. This failure has only been reported for continuously energized applications. The end user should evaluate their applications for this potential failure mechanism. QTNP has notified North Anna, H. B. Robinson, Diablo Canyon, and Hatch.
PDMS material has been identified in the Eaton A200 series starters/contactors with date code T4115 (41st week of 2015) which is outside the range of May 2008 to December 2012 that were originally identified in NRC Event Number 51611 from 2015. This resulted in a few instances where the starter did not immediately open when the power was removed. Notified R2DO (Masters), R4DO (Werner), and PART 21/50.55 REACTORS via email |