Review Article: A Review of the Development and Operational Characteristics of the TALSPEAK Process

Abstract

The separation of trivalent transplutonium actinides from fission product lanthanide ions represents arguably the most challenging aspect of advanced nuclear fuel partitioning schemes. A considerable amount of effort has been dedicated to the development of effective methods for accomplishing this separation, essential for transmutation of the actinides heavier than Pu. Among the methods currently considered to be ready for technological deployment is the TALSPEAK (Trivalent Actinide ‐ Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes) Process, developed in the late 1960s at Oak Ridge National Laboratory. This process is based on the partitioning of lanthanides and actinides between an acidic organophosphorus extractant ((RO)₂PO₂H) solution and an aqueous phase containing a high concentration of a carboxylic acid buffer and a polyaminopolycarboxylate complexant. The latter reagent is principally responsible for holding back the trivalent actinides, allowing the selective transfer of the lanthanides into the organic phase. Several combinations of different extractants and aqueous complexants have been investigated, as have the effect of diluent, temperature and p[H⁺] on separation efficiency. In this report, the prior literature is examined to help provide guidance for potential deployment of the technology in advanced nuclear fuel cycles and to identify opportunities for fine‐tuning the process.

Keywords:

• TALSPEAK process
• trivalent actinides and lanthanides
• DTPA
• lactic acid
• HDEHP