COMPLETE DOCUMENT (1862 kb) - OECD Nuclear Energy Agency

This recycling system can be operated flexibly by combining LWR and FBR cycles. Its main
features are the electrolytic transfer of uranium and plutonium to solid and liquid double cathodes and
recovery of transuranium elements from the salt by reductive extraction or electrorefining. Oxide fuels
are first reduced to metals with lithium or calcium. Expected advantages are improved proliferation
resistance, simplified criticality control and economically compact equipment. The disadvantage is lack
of industrial experience with a high-temperature process using corrosive materials.
Figure II.10 Actinide recycling system based on a pyrochemical processing of HLW and
FR metal-fuel FR-irradiation
1.2.2.1 Pyrochemical reprocessing of metal and oxide fuels
The basic pyrochemical process developed at ANL [43] consists of anodic dissolution of spent
fuel, partial recovery of uranium on a solid cathode, and electrolysis of plutonium with the remaining
uranium into a liquid cadmium cathode, with an electrolyte of LiCl-KCl above 500°C [44]. The flow
diagram for metal fuel is shown in Figure II.11. An anodic dissolution test on EBR-II fuel showed that
most of the alloy was dissolved into the salt while a little cladding material remained as residue [45].
Recovery of uranium on the solid cathode has been thoroughly demonstrated with 10 kg deposited in a
dendritic formation [46]. The condition of effective deposition on the solid cathode was investigated by
changing the ratio of surface area of cathode to anode at CRIEPI [44].
Oxide fuels to be treated by this process must first be reduced to metal. ANL experimentally
evaluated several methods, such as salt transport, the Zn-Mg process, Mg extraction and lithium
reduction. The lithium process has the advantages of a lower operating temperature, less corrosive
environment and small amounts of salt waste. Single element tests with uranium, plutonium and other
elements, demonstrate the reduction to metallic form in LiCl or LiCl-KCl above 500 o C, resulting in the
formation of lithium oxide which will be electrolytically decomposed for recycling.
Multi-element tests of the whole process, preferably with real fuels, are going on to find out
the technical feasibility of lithium reduction, proceeding to find the best operating conditions for pilotand
larger-scale trials at CRIEPI.
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