Actinide(III) Recovery from High Active Waste Solutions Using Innovative Partitioning Processes

Abstract

The selective partitioning of minor actinides from the fission products and separate treatment by transmutation can considerably improve long-term safety of the residual waste for its subsequent future disposal in a deep underground repository. The present chapter will summarize about the ongoing research activities at Forschungszentrum Jülich (FZJ) in the field of actinide partitioning using innovative solvent extraction processes. European research over the last few decades, i.e. in the NEWPART, PARTNEW and the recent EUROPART programs, has resulted in the development of a multicycle process for minor actinide partitioning. In this respect, numerous European partners cooperate closely in European projects. These multicycle processes are based on the co-separation of trivalent actinides and lanthanides (e.g. DIAMEX process), followed by the subsequent trivalent actinide/lanthanide group separation in the SANEX process. Apart from optimizing the properties of the solvent for optimal extraction and separation efficiency, extractant stability is a critical issue to be studied. In this chapter, we will focus mainly on the development of flowsheets for the recovery of americium and curium from high active waste solutions, and testing them in mixer-settler and centrifugal contactors. The scientific feasibility of the processes developed will be demonstrated on a laboratory scale using synthetic and genuine fuel solution. The future direction of research for the development of new processes within a new European project (ACSEPT) is briefly discussed in the conclusion.