The criterion of equivalence used in the ―Methodology for quantity calculation of high-level waste to be returned back to Ukraine after technological storage and reprocessing of VVER-440 spent fuel assemblies‖ is described and substantiated. It is shown that this criterion ensures radiation equivalence of high-level wastes (HLW) to be returned, as well as those from reprocessing of spent fuel assemblies of Ukrainian NPPs at all stages of subsequent treatment.