Abstract <p>A mathematical model is formulated to describe the plasma treatment of spent nuclear fuel (SNF) reprocessing wastes, which are fed into an air-plasma flow as dispersed aqueous–salt–organic compositions (ASOCs) containing ethanol or acetone as organic additives. The model describes the coupled kinetics of droplet heating and evaporation, interphase momentum exchange, and heat and mass transfer within a one-dimensional two-phase-flow framework, which is cast in dimensionless form to enable parametric analysis and scale-up. Thermochemical calculations are used to determine optimal ASOC formulations that provide an adiabatic combustion temperature of approximately 1500 K, thereby ensuring energetically efficient plasma operation and complete oxidation of the organic fraction. The influence of key operating parameters—initial plasma temperature and velocity, droplet size and injection velocity, and liquid-to-gas mass ratio—on the spatial extent of droplet evaporation is investigated numerically using a fourth-order Runge–Kutta integration scheme with controlled accuracy. The results show that, at temperatures above about 1500&#xa0;K, the overall rate of plasma utilization is governed by solvent (water) evaporation, whereas further increases in inlet plasma temperature have only a weak effect on the length of the complete-evaporation zone. In contrast, droplet size and flow hydrodynamics exert a dominant influence: reducing the initial droplet diameter from 100 to 40 μm and decreasing the gas-flow velocity from 90 to 10 m s^–1 lead to multi-fold reductions of the evaporation length, allowing complete evaporation within reactor lengths not exceeding 1 m. The resulting model serves as a physically sound and computationally efficient means of forecasting and refining droplet-evaporation dynamics in air-plasma reactors designed for processing wastes from spent nuclear fuel reprocessing and other liquid radioactive waste streams.</p>