Development of the ERIX process for reprocessing spent FBR-MOX fuel. A hot test on U and Pu recovery and the process improvement

To develop an advanced technology for reprocessing spent FBR-MOX fuel, we have been studying a new aqueous reprocessing system named ERIX Process. This process consists of (1) Pd removal by selective adsorption; (2) electrolytic reduction for the valence adjustment of U, Pu, Np. Ru and Tc; (3) anion exchange separation of U, Pu and Np; and (4) selective separation of MA (Am, Cm) by extraction chromatography. In this work, hot tests of electro-reduction using a flow type electrolysis cell and anion exchange separation by AR-01 packed column for the recovery of U and Pu from an irradiated MOX-fuel solution were carried out according to the main process of the ERIX flowsheet. All of the FPs and MA showed no adsorption and leaked from the column firstly. In the electrolysis, U and Np were effectively reduced to U(IV) and Np(IV) and separated completely from the FPs. On the other hand, a part of Pu was reduced to Pu(III) which mixed with FPs in column separation. To achieve a successful separation of Pu from FPs, the ERIX process was improved by adopting an additional anion exchange column to recover Pu(IV) prior to the electro-reduction of U(VI). (author)