Minor actinide burning in thermal systems

In the previous work carried out by European Nuclear Energy Agency (ENEA) and other research organizations, the burning of minor actinides was considered a by-product of electrical energy production or a way to increase the amount of fissile materials. In the present report,, transmutation is treated as a problem itself. The main target of the work is to find the variables which influence the burning of actinides. In this work, the machine capability evaluation is minimized and the attention is focused on the different parameters acting on actinide burning, namely: the matrix containing the actinides, the irradiation time, the level of flux, the spectrum, the actinide concentration, the absence of 237Np. Secondly the critical parameters' values, or value ranges, which can reduce the actinide risk, at the end of irradiation or at least after 5,000 years of decay, to a value lower than that of natural uranium ore, are evaluated. The neutron flux is the critical parameter for determining the actinide burning; the containing matrix and the initial actinide concentration are important factors too. The system capable of burning the minor actinides and long-lived fission products must have a thermal flux value of about 1.0 x 1016 n/(cm2 sec), a low atomic weight matrix. The Los Alamos spallation system seems to be the closest existing project which can burn both minor actinides and long-lived fission products