ABSTRACT
A severe reactor accident in a light water reactor would result in the release of fission products and other components of the core by vaporisation into the reducing steam environment of the primary circuit. The behaviour of relevant metal/metal oxide systems in the presence of water vapour is not well understood, and much of the present knowledge stems from work undertaken some thirty to forty years ago. Water can react with elemental and oxidic species to form gaseous hydroxides and oxyhydroxides at high temperatures. A summary will be given of the chemistry of a number of relevant hydroxides, with emphasis on the need for more extensive studies to measure their thermodynamic quantities. Equipment has been developed to undertake a preliminary study of vapour transport in inert gas/steam mixtures at ambient pressure and temperatures up to 1000°C, and results will be presented on the transport of indium in steam using this apparatus.
