Abstract: The invention relates to a confinement matrix for the storage or incineration of at least one long-life radioactive element, comprising at least one crystalline boron compound of a rhombohedral structure including the long-life radioactive element(s). The boron compound may be of the B3Si, B6O or B4C type.

Abstract: A neutron absorbent material and a process for manufacturing said material, the neutron absorbent material having great resistance to mechanical damage and more particularly great resistance to crack propagation, which material contains boron carbide and hafnium in the form of powders of fine grain size, and with the manufacturing process it is possible, by reactive sintering of the two powders, to obtain a boron carbide based material having hafnium boride strata, which process comprises a step consisting of mixing boron carbide and hafnium and a reactive sintering step of the mixture obtained.

Abstract: The invention relates to a neutron absorbent material and a method of manufacturing such a material. The neutron absorbent material of the invention is a material having a high resistance to corrosion and high mechanical strength. This material is based on hafnium diboride and additionally comprises hafnium dioxide. The method of the invention enables one to reduce the sintering temperature of a composite material based on hafnium diboride. It includes a step that consists of mixing hafnium diboride and hafnium dioxide and a step of sintering the mixture obtained.