Irradiation Swelling Analysis of Beryllium Reflectors in KJRR

It is reported that Beryllium swells under fast neutron irradiation, which is used as major reflectors in KiJang Research Reactor (KJRR). It would affect a flow path in the core and make difficult to dismantle the core components. So, it is important to estimate the amount of swelling of the Beryllium reflectors and to prepare a maintenance scheme to prevent the severe condition based on the estimation. In this study, it is simulated using finite element method (FEM) how much the Beryllium reflectors swells in the irradiated environment of KJRR. The behavior of the Beryllium reflectors in KJRR under irradiation is successfully simulated by the swelling model and FEM. Based on the simulation results, it is assessed whether the amount of swelling could geometrically affect the core configuration. It is concluded that periodic maintenance such as shuffling, rotation or replacement is necessary. Also, it is required that the maintenance period shall be determined with specific swelling coefficient in the future study