Neutron Economy of Transmutation of TRU in Thermal and Fast Neutron Fields

Abstract

Neutron economy of the transmutation of TRU was examined in well thermalized, thermal and fast neutron fields. Burn-up chains of 237Np, 241Am and 243Am, which are the main TRU nuclides in the high level waste, were calculated in the flux region from 1014 to 1017 n/cm2.s. Numbers of neutrons absorbed and produced of each chain were calculated using JENDL-3. The net number of neutron produced n net, which was obtained by the difference of the two numbers, largely varied with the neutron fields, the nuclides and the flux levels. The n net value in the fast neutron field was positive (0.0–1.0) for 237Np, 241Am, 243Am and TRU with the nuclide composition in the high-level waste generated by the conventional PWR. The transmutation of TRU by fission can be performed with producing neutrons in the fast neutron field. On the other hand, the n net value was negative for the well thermalized and thermal neutron fields. For TRU in the high-level waste, the values in those fields were —1.0 at 1014 n/cm2.s and 0.0 at 1...