Synthesis of Actinide Chlorides as Fuel for Fast Molten Salt Reactor

In this work, the synthesis of pure actinide chlorides such as PuCl₃ and AmCl₃ is investigated. Actinide chlorides are synthesized based on a gas-solid reaction between an actinide precursor and a chlorinating agent. Chlorination experiments were carried out in a static bed reactor under flowing gas. The impact of several reaction parameters such as actinide precursor (oxide or oxalate), gas (chlorine or hydrogen chloride), chlorinating time and temperature were studied. The purity of formed products were evaluated first by X-ray diffraction measurements and then by electrochemical measurements and chemical analysis after leaching. Thermodynamic calculations were also performed to support results. The carbochlorination of PuO₂ was conducted in the temperature range of 600 C to 800 C with chlorine gas as a chlorinating agent and the presence of solid carbon. Results show that conversion efficiency mainly depends on the chlorinating temperature and the contact between the oxide and the chlorinating agent. Volatilization of plutonium was observed with chlorine gas. The hydrochlorination of plutonium oxalate was performed at lower temperature and exhibited a good conversion to PuCl₃. Americium chloride was synthesized using both carbochlorination and hydrochlorination techniques. Americium seems to be easier to chlorinate than plutonium, since AmO₂ could directly react with HCl gas at 600 C to form AmCl₃. The purity of actinide chlorides needs further investigations and salt purification and actinide behavior in molten salt is the subject of ongoing studies