Improvements in nuclear reactors

A reactor core structure is described composed of vertical parallel fuel element assemblies, arranged side by side, each assembly comprising a number of spaced parallel fuel pins enclosed within a tubular casing that has a spike extending from its lower end. The spikes of the fuel element assemblies engage upper and lower apertures in a core base support structure and are elastically extended into engagement with the apertures so that the lower ends of the fuel element assemblies are pulled into abutment with the core support structure. The spikes may have upper and lower circumferential bearing surfaces that engage the apertures in the core support structure, and the lower ends of the spikes and the core support structure may have fittings for effecting demountable bayonet couplings. The fuel element assemblies are supported independently of one another and are stabilised against random vibration induced by coolant flow through the reactor core. (U.K.)