Density effect of reactivity in a heavy-water power reactor operating in the (233)U self-fueling regime

The void coefficients of the reactivity of different channel-type power reactors are compared. It is shown that a heavy-water channel reactor operating in a self-fueling regime within a uranium-thorium fuel cycle is just as nuclear-safe as CANDU type reactors. When composite fuel assemblies containing fuel elements with fuel and a ThO(2) target are used, such a reactor possesses negative void and therefore power coefficient of reactivity. Consequently, its nuclear safety is substantially higher than that of channel power reactors cooled by heavy or light water.