Fuel plutonium partitioning methods

The Purex process will continue to be the main method for the reprocessing of nuclear reactor fuels. The inherent flexibility of this process allows for modifications needed to accomodate a large range of fuel compositions and product specifications. Among the several plutonium partitioning methods developed, those avoiding the introduction of extraneous metal ions... 

The first two methods require rigid process control except in natural or slightly enriched reprocessing plants before plutonium partitioning. Other features of the layout include a calculated pitch on the process cell floors so that a major spill will not cause the solution depth to exceed criticality. A steam jet and sump pump with alarm devices are located in a geometrically safe sump at the low point in the cell area. To avoid loss of fissionable-fuel material, there should be no gravity connections between the process tanks and the waste storage area. 

FP-4 (zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony)—are only slightly soluble (<1 wt %) in the process alloy, thus will partition between both product streams. The process, as presented, offers no method of FP-4 removal and possibly an unwanted increase in these products would occur if the fuel were to be recycled. However, it would be possible to separate the FP-4 from the plutonium/thorium stream by recovering the plutonium/thorium by hydriding. The FP-4 do not form stable hydrides and would remain in solution. 

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