The following information was received by facsimile:
Rotork designs and manufactures valve actuators; a product that attaches to a valve to permit the remote operation of the valve.
[Rotork Controls] is writing to notify the NRC that Duke Energy has received from Rotork a basic assembly containing a defective sintered gear Pt. No. 22641. No other [NRC] licensee has received this part. The defective component is part of an optional subassembly called an 'Add On Pack' (AOP). Duke Energy purchased AOPs with all Rotork NA1E type actuators.
The defective gear could cause the AOP to seize and fail to operate. The actuator will continue to perform its safety related function with a seized AOP. The AOP provides position information, through auxiliary switches, during the actuator's operation.
Duke Energy was first notified of the condition on July 16, 2010 and on August 6, 2010 received a formal letter in which the extent of condition was communicated. Rotork proceeded to investigate the problem, run life tests and understand the failure mode. On September 3, 2010 Duke Energy informed Rotork in writing that the AOP must support the design-basis function of the associated valve/actuator assembly. On the same date Rotork shared with Duke energy [information] which confirmed that the gear design was sound and that the gear failure was attributable to the supplier's manufacturing process.
The gear supplier's production process has been corrected and Rotork quality assurance is verifying that subsequent batches are conformant to specification. Duke Energy is being provided with replacement
AOPs and conformant gears on an as requested basis.