Thermal Effects in the Matrix with the Rare Earth Fraction

High-level waste (HLW) separation into fractions simplifies isolation in matrices and disposal. One of these fractions consists of rare earths (REE) and minor actinides (MA = Am, Cm). Among the rare earth elements there are the isotopes ¹⁴⁴Ce, ¹⁴⁷Pm, ¹⁵¹Sm, and ^154,155Eu with half-lives of up to 93 years; decay of the nuclides will cause heating of the matrices with HLW. It has been shown that preliminary storage of the REE–MA matrix for ten years or more will significantly reduce the content of REE radioisotopes and their contribution to temperature increase in the geological repository.