MODIFIED TRUEX PROCESS FOR THE TREATMENT OF HIGH-LEVEL LIQUID WASTE

The TRUEX process has been examined to recover Am and Cm from the high -level liquid waste of Purex reprocessing plant. Continuous counter cu rrent extraction and back-extraction experiments were carried out by a mixersettler using simulated waste solution for three process flowshe ets, i.e. a process flowsheet developed by Argonne National Laboratory and other two process flowsheets which were modified in the scrub sta ge. The result indicates that the process flowsheet of Argonne Nationa l Laboratory cannot be applied for the high-level liquid waste contain ing high concentrations of lanthanide and actinide elements because of the formation of insoluble salts of these elements with oxalic acid, which is added to restrict the extraction of fission products such as Mo and Zr. A modified process flowsheet, which had only one scrub stag e with high concentration of nitric acid, was found to be the best of three process flowsheets examined, where Nd as a simulated element of Am and Cm was sufficiently recovered and any precipitation of oxalate salt was not observed.