Analysis of Air Cooling Performance in the Coil Stack Assembly for APR+ CEDMs

The control element drive mechanisms (CEDMs) are electromechanical devices for withdrawing, inserting, holding or tripping the control element assemblies (CEAs). The driving power for CEDMs is supplied by the coil stack assembly mounted on the motor housing assembly. The Coil Stack assembly is heated by the motor housing assembly contacted with reactor coolant as well as electric resistance of coil. The CEDMs are cooled by air ventilation. The cooling air around the CEDMs flows into the individual cooling shroud and extracts heat from the coil stacks while it passes between the shroud and coil housing. The cooling performance of the CEDMs is closely related to the geometry configuration of coil stack assembly. The expansion of air passage and additional cooling fins are considered to improve the cooling performance of APR+ CEDMs. In this study the optimal design conditions of APR+ CEDMs are investigated by flow analysis