Abstract: A method of making a nuclear fuel element for a fission reactor. A solid body of an alloy of zirconium and nuclear fuel metal is exposed to hydrogen at an elevated temperature to hydride the zirconium. The hydrided alloy is exposed to oxygen at a lower temperature to form a continuous oxide layer about its exterior surface and is employed in a gastight container as a fuel element. The hydrided alloy may be exposed to oxygen at a temperature of at least about 300.degree. C. prior to its enclosure in the container, or the hydrided alloy may be enclosed in the container together with a quantity of an oxygen-providing material, such as CO.sub.2 or H.sub.2 O, sufficient to oxidize its exterior surface when the fuel element is raised to an elevated temperature.