ACTINIDE TRANSMUTATION PROPERTIES OF THERMAL AND FAST FISSION REACTORS INCLUDING MULTIPLE RECYCLING

To decrease the long-term radiotoxicity risk from nuclear waste, inves tigations were performed to transmute long-lived radwaste nuclides: ac tinides. in particular isotopes of Pu, Np, Am, and fission products, t o short-lived or stable nuclei. First, from neutron spectra and result ing neutron reaction cross-sections, transmutation half-lives, and fis sion-to-capture ratios, the priority of fast over thermal reactors wit h respect to transmutation is derived. Second, transmutation calculati ons for a park of PWRs and fast CAPRA burner reactors show the ability of CAPRAs to reduce Pu and minor actinides with homogeneous multiple recycling of Pu and Np and heterogeneous multiple recycling of Am. Acc umulation of Ist generation PWR-Pu is stopped. Because of Pu deteriora tion, reactivity requirements and Pu less than or equal to 45 % in (U, Pu)-MOX, 58 % of 'bad quality' and proliferation-resistant Pu from rep rocessing of spent CAPRA fuel has to be excluded from recycling. Homog eneous 5 % admiring of Np results in a constant-level Np park inventor y. The relatively large consumption of Am is counteracted by a signifi cant in-core production of Am, resulting in a net increase of park Am. (C) 1998 Elsevier Science S.A.