Minor Actinides: Partitioning, Transmutation and Incineration

Abstract

Plutonium isotopes, but also the isotopes of minor actinides: mainly neptunium, americium and curium can be fissioned by neutrons in the core of nuclear reactors. They also can be transformed as non-fissile isotopes by neutron capture into fissile nuclides (transmutation). Incineration of 99% of the plutonium, neptunium, americium and curium would decrease the long term radiotoxicity of the high active waste (HLW) such that the radiotoxicity level of natural uranium would be underrun already after about 3 × 104 years. This requires chemical separation of plutonium, neptunium, americium and curium and the fabrication of fuel elements with these actinides. These chemical separation methods and the fuel refabrication methods were already developed by research and development programs and demonstrated in pilot plants or at laboratory scale. The possible incineration rates for the different actinides in different reactor types (light water reactors, liquid metal cooled fast breeder reactors and accelerator driven systems) have been thoroughly investigated. Reactor strategies with light water reactors operating in symbiosis with liquid metal cooled fast breeders or accelerator driven systems are feasible. The different reactor and fuel cycle strategies have different radioactivity loads and different radiotoxicity levels within the different parts of their fuel cycle. Whereas the radiotoxicity can be drastically decreased in the back end of the fuel cycle, the masses of plutonium and minor actinides and their radioactivity and radiotoxicity can be higher during reprocessing and refabrication. Transmutation and destruction of long-lived fission products is only feasible with reasonable efficiency for Iodine-129 and Technetium-99. © Springer-Verlag Berlin Heidelberg 2012.