No abstract

The Recycle Fuel Fabrication Laboratory (RFFL) is a licensed nuclear facility designed to produce experimental quantities of mixed oxide fuel for reactor physics tests and demonstration irradiations. Since its refurbishment in 1996, several fuel fabrication campaigns and research projects have been completed. The RFFL is the only facility in Canada capable of handling significant quantities of plutonium and other actinides. In this context, effort has been put forth in recent years to demonstrate capabilities in new fields, such as actinide chemistry. One of the first experiments in actinide chemistry conducted in the Facility was devoted to the separation and purification of 241Am from aged PuO2. The experimental work presented here, was conducted to establish actinide separation capability at the RFFL and demonstrate the staff expertise to perform these types of separations. The separation experiments were carried out using ion exchange columns packed with basic anion exchange AG1-X4 resin. More than 92% of the 241Am contained in the starting PuO2 solution was recovered in the experiments; however, some plutonium was also found in the washing effluent fraction. The final americium concentration of the washing effluent fraction was estimated to be about 50% of the total heavy elements present. More than 93% of the purified plutonium retained in the column was eluted. The experimental results are discussed in terms of the speciation behaviour of the Am–Pu–N–H2O systems using E-pH thermodynamic equilibrium diagrams and the maximum ionic exchange capacity of the resin.

Thoria–plutonia (ThO2–PuO2) pellets with a nominal composition of 9.0 wt% PuO2 were prepared using a fabrication route similar to an industrial process for production of urania–plutonia (UO2–PuO2) mixed oxide fuel. The green fuel pellets were separated into 2 batches and the sintering of each batch was carried out under a reducing atmosphere at 1820 °C or 1750 °C. The distribution of plutonium (Pu) in the sintered pellets was investigated by electron probe microanalysis using X-ray mapping and quantitative point analyses. The results show that the pellet samples consist of Pu-rich agglomerates with Pu content close to that of the mastermix blend and a thorium (Th)-rich matrix. The matrix and the Pu-rich agglomerates are separated by a transition zone with Pu content varying from practically nil to the Pu content of the Pu-rich agglomerates. X-ray maps taken from random regions of the centre of the pellets show different sizes of Pu-rich agglomerates irregularly dispersed in the Th-rich matrix. Image analysis of the Pu X-ray maps indicate that the average diameter of the Pu-rich agglomerates of the material sintered at 1820 °C and 1750 °C were 68 μm and 161 μm, respectively.