The mathematical and laboratory modeling of thehigh-level waste vitrification process is able to reveal the mechanism of spinelcrystal formation, their interaction with a melt and settling. This enables tofind conditions for higher waste loading into vitrification facility. A model ofa perfect mixer has been developed by authors with the aim to examine thecrystal settling and to compare results with the numerical mathematical model.This model is based on the mass balance of inputted, outputted, nucleated,growing or dissolving and settling crystals in the melting space. To completethe description of possible melter behavior, similar relations were derived andare presented for the piston flow in the melter.
