Transmutation of americium in fission reactors

To get a considerable reduction of the radiotoxicity due to americium, a thermal neutron fluence of 2.1022 cm-2 or a fast neutron fluence of 2.1024 cm-2 is required. Irradiation in a thermal neutron flux leads to lower masses of 234U and precursors and of 237Np and precursors, but to higher curium masses and much higher neutron emission rates than irradiation in a fast neutron flux. Therefore, irradiation in a fast neutron flux has preference when multiple recycling is adopted. When once-through burning is applied, irradiation in a thermal neutron flux can be applied. Then irradiation in a HWR has preference above irradiation in a PWR or in a HTGR. (orig.)