Abstract: A complex separation process and apparatus for decreasing non-radioactive salt content of waste solutions of nuclear power stations. The process significantly decreases in non-radioactive salt-content of waste solutions arising from nuclear power stations.Process is essentially based upon a suitable combination of up-to-date separating operations, such as precipitation, filtration, ultra-filtration, reverse osmosis, ion-exchange, evaporation and crystallization. Practically total amount of components carrying radioactivity (except tritium) can be effectively separated from the non-radioactive salts. Part of inactive salts (alkali nitrates) can be handled as industrial waste and the other part (boric acid) can be recycled. In the process precipitation, ion-exchange, reverse osmosis and crystallization are operations completing or replacing each other. Reverse osmosis is used not only for separating water and soluble, but for the separation of solved components.