Effect of Rare Earth Element Recycling on Sodium Cooled Fast Reactor Core Performance

Korea Atomic Energy Research Institute (KAERI) has been developing a sodium cooled fast reactor (SFR) for enhancing the natural resource utilization and effectively managing the spent nuclear fuel (SNF) discharged from light water reactor (LWR) in Korea. The metal fuel recycled through a pyrometallurgical process of LWR SNF is loaded into the SFR. The charged fuel contains recycled transuranic elements and rare earth (RE) elements. RE element was classified as a lanthanum group in periodic table and included in the fission products as about 20 %. Since the chemical behavior of RE element is very similar to that of transuranics, the RE elements could not be completely separated from TRU elements through pyrometallurgical process. RE elements play as a neutron poison in the reactor core while inclusion of those to charged fuel makes the SFR-pyroprocessing system more resistant against a proliferation. Therefore, a quantification of maximum RE recovery fraction and clarification of its effect on the core performance and safety is crucial for the design of a pyrometallurgical process