Cooling device for the vertical adjacent fuel rods of a metal-cooled fast-breeder

摘要

A liquid metal cooled fast breeder nuclear reactor of the kind wherein the fuel assembly is submerged in a pool of liquid metal coolant in a primary vessel which is housed in a concrete vault. The fuel assembly, which comprises a multiplicity of elongate fuel pins, is sub-divided into a plurality of elongate sub-assembly constructions which upstand side-by-side. The fuel assembly has an inner zone comprised mainly of fissile material and a surrounding outer zone comprised mainly of breeder material. The sub-assemblies in the outer zone include electro-magnetic braking devices for regulating the flow of coolant through the sub-assemblies and the magnetic fields of the electro-magnetic braking devices are temperature sensitive being arranged so that as the power output of the breeder sub-assemblies increases the electro-magnetic resistance to coolant flow is reduced thereby maintaining the temperature of the coolant outlets from the sub-assemblies substantially constant.