Experimental data are presented on the motion velocity of model materials simulating the properties of a polyfractional mixture of spent fuel from a nuclear power station (finely dispersed components with d f< 0.08 mm and pieces of fuel rod claddings with d f = 15-50 mm) and separation of fine fraction, as well as on the effective coefficients of diffusion and thermal diffusivity, which characterize how intensively reverse mixing proceeds in the elements of vibration apparatuses for oxidative recrystallization of spent fuel. © 2008 MAIK Nauka.