Method for iodine radionuclides separation from primary coolant samples

A method is presented for isolating iodine isotopes from aqueous coolant of the nuclear power plants’ first circuit. At first, all forms of iodine radionuclides are converted into molecular form by the sequential addition of a carrier–potassium iodide, as well as hydroxylamine chloride, nitric acid and potassium nitrite. Then molecular iodine is transferred into the gas phase and volatile iodine radionuclides are immobilized on a membrane impregnated with metallic silver. The main advantage of the method is high selectivity of iodine release in relation to radionuclides interfering with the measurement of its activity.