Physics of liquid metal fast breeder reactor safety

The main physical features of LMFBR safety are summarized with particular reference to the maximum possible mechanical energy release in a hypothetical core disruption accident. It is likely that such a postulated fuel melting accident would lead to a nonenergetic disassembly of the core. With pessimistic estimates of reactivity increaases, but not derived from any mechanistic point of view, mechanical energy impacts on the reactor vessel of 100 MJ have been calculated for the Clinch River Breeder Reactor. These are containable with the present design, and the increase should vary only linearly with increased power for future designs of similar concept. Various possible steps are discussed to increase the certainty of these conclusions.