Curium - Safety

Safety

Owing to its high radioactivity, curium and its compounds must be handled in appropriate laboratories under special arrangements. Whereas curium itself mostly emits α-particles which are absorbed by thin layers of common materials, some of its decay products emit significant fractions of beta and gamma radiation, which require a more elaborate protection. If consumed, curium is excreted within a few days and only 0.05% is absorbed in the blood. From there, about 45% goes to the liver, 45% to the bones, and the remaining 10% is excreted. In the bone, curium accumulates on the inside of the interfaces to the bone marrow and does not significantly redistribute with time; its radiation destroys bone marrow and thus stops red blood cell creation. The biological half-life of curium is about 20 years in the liver and 50 years in the bones. Curium is absorbed in the body much more strongly via inhalation, and the allowed total dose of 244Cm in soluble form is 0.3 μC. Intravenous injection of 242Cm and 244Cm containing solutions to rats increased the incidence of bone tumor, and inhalation promoted pulmonary and liver cancer.

Curium isotopes are inevitably present in spent nuclear fuel with a concentration of about 20 g/tonne. Among them, the 245Cm–248Cm isotopes have decay times of thousands of years and need to be removed to neutralize the fuel for disposal. The associated procedure involves several steps, where curium is first separated and then converted by neutron bombardment in special reactors to short-lived nuclides. This procedure, nuclear transmutation, while well documented for other elements, is still being developed for curium.