Abstract: Fuel and fertile rod for a nuclear reactor. It comprises a can, a column of fissile and/or fertile pellets within the can and end plugs welded to the two ends of the can. The column of pellets is held in place by two tubular spacers of limited thickness and with rounded edges abutting against the two ends of the fuel column and set with a fixed dimension to the can. The column of fissile and fertile pellets can also be held in place by a supplementary positioning setting of the fertile pellet column.

Abstract: The present invention relates to an upper neutron protection device for a nuclear reactor assembly.This device comprises at least one container partly filled with a neutron-absorbing product and maintained within a wall located in the upper part of the assembly by at least one spacing plate.Application to fast neutron reactors.

Abstract: The fuel assembly comprises at least one cluster of canned-fuel pins disposed on a uniform lattice within a sleeve defining a duct through which a coolant is circulated. Each fuel pin is provided at least over the greater part of its length with a helical spacer member which determines the minimum spacing between the fuel pin and the adjacent pins or the sleeve. The internal face of the sleeve is provided with recesses in which the spacer members of the lateral pins of the cluster are partially engaged.The fuel assembly finds an application in nuclear reactors of the liquid-sodium-cooled fast breeder type.This is a continuation, of application Ser. No, 395,454 filed Sept. 10, 1973 now abandoned.