Published online by Cambridge University Press: 04 March 2018
Sodalites have been investigated experimentally for the capture and long-term containment of 129I, a significant and hazardous waste product of the nuclear fuel cycle. Sodalites are zeolite-type structures commonly occurring in nature in alkaline igneous rocks and having the prototype formula Na8(AlSiO4)6Cl2. The crystal structure is based around β-cages consisting of corner-sharing SiO4 and AlO4 tetrahedra. In the centre of the β-cage is an anion X. Iodine captured by sodalites sits in the centre of the β-cages as iodide anions. Silver iodide (AgI) plays an important role in the capture and subsequent processing of 129I in the nuclear fuel cycle. Using ab initio density functional theory (DFT) modelling, we investigate the energetics and feasibility of iodine capture and containment in mixed cation sodalites Na8-xAgx(AlSiO4)6I2, and compare the results with experimental observations.