Development of Plutonium Fuelled Coated Particles for Irradiation in the Dragon Reactor Experiment. Dragon Project Report

The development of Pu fuelled coated particles based on a kernel consisting of PuO₂/PuO₃ dispersed in a carbon matrix bonded with furfuryl alcohol polymer and surrounded by a complex coating of pyrocarbon and silicon carbide is described. Details are given of the manufacture of fuels coated at ∼1500°C for irradiation tests in the Studsvik and Dragon Reactors. Also described is the preparation of a fuel where specification was dictated by the requirements of a feed fuel for a feed/breed HTR. In this case the fuel kernels of composition PuO_x/20C and of ∼500 μm diameter were coated with a triplex PyC/SiC/PyC coat of 160-170 μm, the outer PyC layer being laid down at 2000°C. Evidence is presented which suggests that if a sufficiently high partial pressure of carbon monoxide is maintained over the PuO₂/C fuel kernels during their heat treatment and during the early stages of coating with the initial pyrocarbon layers, this type of fuel can be prepared without incurring significant losses of plutonium. (author)