Affinity of volatile fission products by a ternary intermetallic electride CaRuSi

Intermetallic electrides are generally more air-stable than conventional ionic electrides, making them attractive for practical fission-product capture. Density functional theory calculations were used to investigate the encapsulation of volatile fission products in the layered CaRuSi electride. Encapsulation of Kr, Xe, Rb, and Cs is thermodynamically unfavorable, whereas Br, I, and Te are favorably stabilized as anionic species. Encapsulated Br2, I2, and Te2 also dissociate spontaneously to form adjacent anions. Although its trapping ability is weaker than that of more electron-rich electrides, CaRuSi offers a chemically stable and selective host for capturing reactive halogen and chalcogen fission products. These findings highlight interstitial electron availability as a key design parameter for developing air-stable materials for selective nuclear off-gas treatment.