One-dimensional yttrium silicide electride (Y5Si3:e−) for encapsulation of volatile fission products

Abstract

Better ways are needed to capture radioactive volatile fission products (Kr, Xe, Br, I, Te, Rb, and Cs) discharged during the reprocessing of spent nuclear fuel in order to reduce the volumes of produced waste and minimize environmental impact. Using density functional theory, we examine the efficacy of a one-dimensional yttrium silicide electride (Y5Si3:e−) as a host matrix to encapsulate these species. Endoergic encapsulation energies calculated for Kr, Xe, Rb, and Cs imply they are not captured by Y5Si3:e−. Encapsulation is exoergic for Br, I, and Te with respect to their atoms and dimers as reference states, meaning that they can be captured effectively due to their high electronegativities. This is further supported by the formation of anions due to charge transfer between Y5Si3:e− and Br (I and Te). The selectivity of this material for these volatile species makes it promising for use in nuclear filters.