Environmentally protective Method of treating an aqueous radioactive fluid (AF) in a nuclear reactor cycle or radwaste system to selectively capture or remove radioactive isotopes in a reduced quantitative package to minimize radwaste generated and revitalize neutron absorption capacity of nuclear reactor coolant by separately carrying away boron constituents, when B.sub.10 is later added. The method includes: demineralizing the (AF) by rough ion exchange and lowering the pH of salts, boron and non- radioactive substances so that the boron can later pass through an RO; polishing by reverse osmosis; dividing the (AF) into a permeate liquid volume and a reject liquid volume, each having certain characteristics; recycling the reject liquid volume back into demineralizing step for removing generally most of the radioactive isotopes to generate a demineralizer effluent; and conveying the permeate liquid volume to the outside ambient environmental release point for liquid effluents of the (AF); dividing the demineralizer effluent into a further permeate liquid volume and a further reject liquid volume having certain characteristics; and conveying the further permeate liquid volume to the outside ambient environmental release point of the invention.