The changes in chemical constitution within cores of fast breeder reactors during hypothetical accidents

The changes in chemical constitution which occur within a fast reactor core when the cladding of the fuel and breeder elements is breached and when the core degrades with melting of the fuel in hypothetical accidents are described in this paper. The conditions for reactions of liquid sodium with urania and with urania-plutonia solid solutions are defined, and experimental information on the equilibria and kinetics of the reactions are given. Experimental studies which have determined the likely constitution of a mixture of urania, fission product elements and stainless steel (core debris) are described. The influence on the constitution of the presence of an uranium carbide breeder or a boron carbide absorber has been studied