Classification and ranking of the solid solution on thier reaction to the irradiation is suggested on the basis of binary system structure controlling by mixing enthalpy sign, melting temperatures relation of components and solidus curves slope. Several combinations of these characteristics permit to pick out three groups of substitutional elements capable to form the vacancy-solute atom complexes either low-mobile or fast-mobile ones as compared to monovacancies migration. The radiation hardening (and embrittlement) of binary alloys should be intensified respectively either due to heterogeneous point defect clusters nucleation on solute traps or due to solute atom clusters/precipitate formation. A local cohesion decrease may also occur especially if low-melting elements (characterized by low surface energy) are segregating on internal sinks or grain boundaries. The predicted specifics of different alloy group under irradiation and during post-irradiation annealing were experimentally examined using a wide set of Fe-base alloys. A good agreement was find between expected and really observed behaviour of alloys.