The Combined Nomenclature (CN), v1:2018
2844: Radioactive chemical elements and radioactive isotopes, incl. their fissile or fertile chemical elements and isotopes, and their compounds; mixtures and residues containing these products
https://www.dst.dk/en/Statistik/dokumentation/nomenklaturer/kn?id=bdccfab4-a71c-4f32-8b96-d3d9ed56013c