PLENTIFUL ENERGY

Figure 10-1. Electrolytic reduction process
The process parameters that require additional development have been
identified. One is the incorporation of forced flow in the cells, which becomes
increasingly important as the scale of cell increases from engineering- to pilot- to
plant-scale. It is important to experimentally demonstrate and understand the
beneficial effects of forced flow. We want flow through the oxide bed to help move
the oxide ions to the anode, but we do not want the flow to entrain oxygen bubbles
in the electrolyte which could back-react with product metal. Improvements of this
kind are not issues of feasibility. A prototype reduction vessel to handle 250500
kg has been designed for eventual testing of all such engineering features.
10.2.5 Experience
Electrolytic reduction has been successfully demonstrated with UO 2 and UO 2 -
5wt% PuO 2 at Argonne-East and with spent light water reactor oxide fuel at
Argonne-West. The initial experiments at ANL-E at laboratory-scale used about
2050 g of heavy metal to demonstrate the extent and rate of conversion.
Experimental results indicate complete conversion (i.e. >99.95%) of uranium,
plutonium, and americium oxide to metal and the rate is satisfactory as well. The
process appeares to be robust and scalable.
Turning now to the results of two series of experiments that established the
process, and are representative samples of the whole, we will see that they give a
good practical sense of the various features and idiosyncrasies of the process.
The first set is representative of the early stages of development, experiments
done at ANL-E aimed at establishing the important principles of direct
electrochemical reduction by Gourishankar et al. [3]. The experiments were done
with about 15 g of UO 2 chips, from 45 microns to 5 mm in size in most cases. The
electrolyte was LiCl1%Li 2 O at 650 o C, based on previous experience. The cells
were operated at one ampere constant current, a level that maximized oxygen
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