Uranium zirconium hydride

Uranium zirconium hydride (UZrH, U-ZrH_x), a dispersion of metallic uranium in a δ-ZrH_1.6 matrix, is used as the fuel in TRIGA reactors.^[1] UZrH fuel is used in most research reactors at universities and has a large, prompt negative fuel temperature coefficient of reactivity, meaning that as the temperature of the core increases, the reactivity rapidly decreases.^[2]

Franco-Belge de Fabrication du Combustible, in Romans-sur-Isère, France, is the only manufacturer of this fuel.^[3]