[en] The basic principles as well as results of experimental studies on purification of the sodium coolant and cover gas in fast reactors are considered. Moreover, data on the reaction mechanism in the cold traps and on separation of oxygen, hydrogen, carbon, sodium-water reaction products, corrosion products, and radioactive contaminants from sodium are presented. The test results of heterophase traps for separating sodium from carbonaceous impurities are described. Finally, some problems of purifying the cover gas of radioactive contaminants are discussed. (author)