The Choice of Pyrocarbon Deposition Agent for Nuclear Fuel Particles

The majority of experience to date relating to pyrocarbon coatings on nuclear fuel particles, as used in the High Temperature Gas Cooled Reactor, is based on methane as the carbon source. Both economic and technical reasons suggest that this may not be the best choice. The properties of the derived pyrocarbons and the relative costs for two different coating agents are briefly described. Although the evidence is not exhaustive, it is concluded that, provided the irradiation behaviour is adequate and that the fission product retention can be entrusted to the silicon carbide layer, the use of propylene as deposition agent should be recommended. (author)