Thermodynamic study on the separation of strontium and barium from LWR spent fuel

Abstract

The separation of high heat load fission products, such as alkaline earth metals, from nuclear spent fuel can significantly reduce the burden of spent fuel disposal. This study investigates the feasibility of separating strontium and barium from light water reactor spent fuel through non-aqueous processes. Process flows were developed for treating spent nuclear fuel by heating it at high temperatures to remove volatile nuclides, followed by chlorination with a chlorinating agent. The chlorinated products were then treated with a precipitating agent in LiCl-KCl molten salt for further separation. The remaining liquid was distilled to recover strontium and barium. Thermodynamic equilibrium calculations were conducted for the process flows. Under the conditions of the process flows, the chlorinating agents MgCl and NHCl both converted SrO and BaO entirely into SrCl and BaCl, respectively. The precipitating agent LiCO exhibited superior separation effectiveness compared to LiPO. Thermodynamic calculations indicate that strontium and barium recovered by MgCl chlorination, LiCO precipitation, and distillation will contain 0.18 %, 1.06 %, and 0.32 % impurities in terms of mass, radioactivity, and decay heat, respectively.