Four-bar linkage modeling and kinematics analysis of an in-vessel transfer system for Prototype Gen-IV Sodium-cooled Fast Reactor

A Sodium-cooled Fast Reactor (SFR) as a Generation IV (Gen-IV) advanced type of nuclear fission energy requires a fuel transfer machine (or a refueling system). It is employed to exchange spent fuel-assemblies during plant operation and other failed core assemblies (CAs). The refueling system provides a means of transporting, storing and handling reactor CAs. For the refueling system of the Prototype Gen-IV Sodium-cooled Fast Reactor (PGSFR), developed by the Korea Atomic Energy Research Institute (KAERI), the PGSFR refueling mechanism was modeled in this paper for the refueling planning, and its kinematics analysis (mathematical steps for forward and inverse kinematics) revealed interesting results by a simple and efficient 2D four-bar linkage system as a kinematics model. This paper argues that restricting coupler link movements is far better not only for more suitable solution forms but also for dynamic safety guarding against collisions with neighboring structures than setting an orientation of the gripper. Computer simulation results in all the angular position information based on the proposed approach report that the total rotation angles of the gripper link for all the core-to-core locations is less than 90° by restricting the coupler link. It was concluded that refueling with the middle component motion restricted is a safe operation strategy with other computational benefits. By taking advantages of the proposed approach, the refueling system can be ready for more precise and safe operations confirmed by kinematics solutions for all of the target core-assembly locations.