Development of a pyrometallurgical partitioning process for transuranium elements. Separation of alkali elements in denitration process

We have developed an advanced technique for use in the denitration step of a pyrometallurgical partitioning process for the recovery of transuranium elements from high-level liquid waste. The use of this technique is intended to solve two problems concerning the significant evaporation of alkali elements and the interaction between denitrated alkali elements and crucible materials. The technique consists of (1) a denitration process at 500degC in which alkali elements remain as stable molten nitrates while other elements are converted to stable oxides and (2) a combination of rinsing with water and centrifugal separation to recover alkali elements in the aqueous phase and to separate them from the other elements. We demonstrated the utility of the technique by measuring the material balance after the technique was applied to the simulated high-level waste. (author)