Reduction of zirconium oxide compounds by lithium metal as a reductant in molten LiCl salt

Abstract The reduction of zirconium oxide compounds by Li metal as a reductant in molten LiCl salt was investigated. This study explored the feasibility of treating damaged nuclear fuel debris, which mainly consists of (U,Zr)O2. The production of metallic Zr by the reduction enables its long-term storage or final disposal through subsequent electrorefining. It was demonstrated that ZrO2 was reduced to Zr metal by Li metal in LiCl salt at 650 °C without formation of Li2ZrO3. In particular, Zr metal was produced without formation of Li2ZrO3 (i.e., no ZrO2 remained) when LiCl salt containing a high concentration of Li metal was used. However, Zr metal was produced with Li2ZrO3 when LiCl salt containing both Li metal and Li2O was added. We also demonstrated that Li2ZrO3 was partially reduced to Zr metal by Li metal in LiCl salt.