transuranic

Transuranic describes elements with atomic numbers greater than 92 (uranium). The term also refers to radioactive waste containing such elements produced by nuclear reactors or weapons programs.

The first transuranic elements, neptunium (93) and plutonium (94), were synthesized in the 1940s. Today transuranic elements include all elements with Z greater than 92, from neptunium to oganesson (118). The early elements lie in the actinide series (93–103); the heavier ones are transactinides. All transuranics are highly radioactive and occur only in very small quantities outside of laboratories; several have practical applications, while many are primarily of scientific interest.

Chemically, transuranics generally resemble the actinides, with common oxidation states from +3 to +6, and they form oxides, fluorides, and various organometallic compounds. Because of intense radioactivity and scarcity, they are produced and handled in specialized facilities with extensive shielding and remote manipulation.

Uses and waste: Plutonium-239 is used as reactor fuel and in weapons, americium-241 in smoke detectors, and several others are employed as research isotopes or specialized neutron sources. The main public safety concern arises from waste containing transuranic elements generated by nuclear fuel cycles and defense programs. Transuranic waste is managed separately from high-level waste and is destined for long-term geological repositories, such as the Waste Isolation Pilot Plant in the United States.