CONCEPT ON COUPLED SPECTRUM B T (BURNING AND/OR TRANSMUTATION) REACTOR FOR TREATMENT OF MINOR ACTINIDES BY THERMAL AND FAST-NEUTRONS/

A conceptual design of B/T (burning and/or transmutation) reactor base d on a modified conventional 1150 MWe-PWR system. with core consisted of two concentric regions for thermal and fast neutrons. was proposed herein for B/T treatment of MA (minor actinides). The B/T fuel conside red was supposed such that MA discharged from 1 GWe-LWR was blended ho mogeneously with the composition of LWR fuel. In the outer region Np-2 3.(241) Am and Am-243 were loaded and burned by thermal neutron. while in the inner region Cm-244 war loaded and burned mainly by fast neutr on. The geometry of B/T fuel slid the fuel assembly in the outer regio n was left in the same condition to those of standard PWR while in the inner region the B/T fuel was arranged in the hexagonal geometry, all owed high fuel to coolant volume ratio. (V-m/V-f), to keep the harder neutron spectrum. Two cases of the Coupled Spectrum B/T Reactor (CSR) with different (V-m, V-f) ratio in tile inner region were studied, and the results for tile tight lattice with (V-m/V-f) = 0.5 showed that t hose isotopes approached the equilibrium composition after about 5 rec ycle period, when the CSR was operated under tile reactivity. swing of 2.8 % dk/k. The evaluations on the void coefficient of reactivity, th e Doppler effect and the reactivity swing showed that the CSR concept has the inherent safety and can burn and/or transmute all kind of MA i n a single reactor. This CSR can burn about 808 kg of MA in one recycl e period of 3 years which is equivalent to the discharged fuel from ab out 12 units of LWR in a year. Copyright (C) 1996 Elsevier Science Ltd