A model for radiation-induced segregation in concentrated binary alloys is described. The model is used to investigate the general properties of quasistationary distributions of point defects and solute in an irradiated alloy with sinks but without precipitates and stress fields. In spite of compositional gradients around sinks arising due to the inverse Kirkendall effect, all sinks remain unbiased toward absorption of defects of a certain species. To derive the rate equations, an effective medium approach for binary alloys is formulated and compared to current ones for pure metals. Considerable difference between growth rates of coherent and incoherent precipitates under irradiation is revealed. The criterion for precipitate stability is expressed in terms of solute solubility. It is shown that irradiation strongly affects the incoherent solubility, whereas the coherent one remains unaltered. A method is presented to construct the radiation-modified phase diagram as well as the temperature-dose rate diagram. The calculations of diagrams are performed for Ni-Si, Ni-Al, and Al-Zn alloys. The comparison of the computed diagrams with the available experimental diagrams is carried out for the Al-Zn alloy.