[en] In the context of the demonstration of the UREX (uranium extraction) process, a separation of uranium and technetium using an anion exchange resin was performed on a simulant solution containing 98.95 g/L of ²³⁸U and 130.2 mg/L of ⁹⁹Tc. After sorption on the resin, TcO₄^- was eluted with NH₄OH, the eluting stream was treated, and the technetium converted to Tc metal (yield 52.5%). The purity of the compound was analyzed: it contains less than 23.8 μg of ²³⁸U per gram of ⁹⁹Tc. Tc metal was characterized by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) spectroscopy; EXAFS analysis clearly confirms the hexagonal structure of the metal obtained after treatment. Uranium was converted to ammonium diuranate and to U₃O₈ in a yield of 88.2%, analysis indicates that the compound contains less than 0.16 μg of ⁹⁹Tc per gram of ammonium diuaranate. (orig.)