Selective Separation of Trivalent Actinides from Lanthanides by Aqueous Processing with Introduction of Soft Donor Atoms

Kenneth L. Nash

关键词: ABSORPTION;    ACTINIDES;    ATOMS;    CHELATING AGENTS;    CROSS SECTIONS;    FISSION PRODUCTS;    IMPLEMENTATION;    NUCLEAR FUELS;    PERFORMANCE;    PROCESSING;    PRODUCTION;    RADIOCHEMISTRY;    RARE EARTHS;    SIDE EFFECTS;    STABILITY;    TALSPEAK PROCESS;    TESTING;    THERMAL NEUTRONS;    TRANSMUTATION TALSPEAK;    actinides;    lanthanides fuel cycle;    separations;    Soft donor complexants;    DTPA;    lactic acid;    HDEHP;    thermodynamics;   

DOI  :  10.2172/964384
RP-ID  :  DOE/ID/14643-3
PID  :  OSTI ID: 964384
Others  :  TRN: US1001095

学科分类：核能源与工程

美国|英语

来源: SciTech Connect

【 摘 要 】

Implementation of a closed loop nuclear fuel cycle requires the utilization of Pu-containing MOX fuels with the important side effect of increased production of the transplutonium actinides, most importantly isotopes of Am and Cm. Because the presence of these isotopes significantly impacts the long-term radiotoxicity of high level waste, it is important that effective methods for their isolation and/or transmutation be developed. Furthermore, since transmutation is most efficiently done in the absence of lanthanide fission products (high yield species with large thermal neutron absorption cross sections) it is important to have efficient procedures for the mutual separation of Am and Cm from the lanthanides. The chemistries of these elements are nearly identical, differing only in the slightly stronger strength of interaction of trivalent actinides with ligand donor atoms softer than O (N, Cl-, S). Research being conducted around the world has led to the development of new reagents and processes with considerable potential for this task. However, pilot scale testing of these reagents and processes has demonstrated the susceptibility of the new classes of reagents to radiolytic and hydrolytic degradation. In this project, separations of trivalent actinides from fission product lanthanides have been investigated in studies of 1) the extraction and chemical stability properties of a class of soft-donor extractants that are adapted from water-soluble analogs, 2) the application of water soluble soft-donor complexing agents in tandem with conventional extractant molecules emphasizing fundamental studies of the TALSPEAK Process. This research was conducted principally in radiochemistry laboratories at Washington State University. Collaborators at the Radiological Processing Laboratory (RPL) at the Pacific Northwest National Laboratory (PNNL) have contributed their unique facilities and capabilities, and have supported student internships at PNNL to broaden their academic experience. New information has been developed to qualify the extraction potential of a class of pyridine-functionalized tetraaza complexants indicating potential single contact Am-Nd separation factors of about 40. The methodology developed for characterization will find further application in our continuing efforts to synthesize and characterize new reagents for this separation. Significant new insights into the performance envelope and supporting information on the TALSPEAK process has also been developed.