The following is a synopsis of information that was provided by Curtiss-Wright via fax:
On August 30, 2023, Enertech (a division of Curtiss-Wright) determined a potential defect for potentiometer part number D2060S based on the inspection of a returned items from Korea Hydro and Electro Power in Korea. A number of returned potentiometers exhibited inconsistent resistance values at certain stroke positions. The potentiometers are used in modulating actuators.
A shorter wiper was used in the manufacture of the potentiometers that introduced the possibility of intermittent separation between the wiper (sliding contact) and the coil at certain stroke positions, resulting in momentary signal interruptions.
The evaluation at Enertech is also ongoing regarding the potential effects of wiper separation on the functionality of the modulating actuator and will not be completed within 60 days. The expected date of completion is December 20, 2023.
South Texas Project Electric Generating Station (Operator: STP Nuclear Operating Company) purchased defective modulating actuators on four occasions.
Questions should be directed to Loretta Anaya, Quality Assurance Manager, Enertech, at 714-982-1856.
Known potentially affected plant(s): South Texas Project
- * * UPDATE ON 12/7 AT 1807 EST FROM SANDRA VALDIVIA TO ERNEST WEST * * *
Enertech has completed their evaluation of the deviation described in their interim report submitted on 27 October, 2023, and concluded that the deviation does not potentially create a substantial safety hazard.
Notified R4DO (Dixon) and Part 21 Group (Email)