An evaluation of the design and performance for a new neutron absorber based on an artificial rare-earth compound

In this study, a neutron absorber based on an artificial rare earth compound, which is a radioactive waste generated from pyro-process, is proposed for use in spent fuel storages. To secure the stable control of criticality with physical and chemical durability, a neutron absorber was designed and fabricated using borosilicate glass and a rare earth compound. The performance of the developed neutron absorber was evaluated in terms of the: (1) criticality controllability with various artificial rare earth compositions, (2) stability after neutron irradiation generated from the spent fuel, (3) radioactivity of the neutron absorber, and (4) physical and chemical properties. Our results show that the neutron absorber can successfully control the criticality regardless of the artificial rare earth composition. Also, we demonstrate that the neutron absorber can be utilized without any additional radiation shielding of the spent fuel storages for a long period of time (more than 100 years). In addition, analysis shows that the absorber has sufficient physical and chemical strength for use in spent fuel storage. We expect that this study will help to minimize the number of radioactive waste storage sites as well as reduce the disposal costs.