The Combined Nomenclature (CN), v1:2024
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=ff35b666-b08b-41b5-bea1-78e213f89ca8