Nuclear fuel cladding tube

In a nuclear fuel cladding tube having a zirconium base alloy as a main constituent, a metal layer (an intermediate layer) of lower corrosion resistance than that of the zirconium base alloy is disposed at the outer layer of the zirconium base alloy layer, and the zirconium base alloy layer is disposed further to the outer layer. That is, if the main constituent is composed of zircaloy-2 or zircaloy-4 and the intermediate layer is composed of a pure zirconium, since the oxygen concentration in the oxides formed from the pure zirconium is greater than that of the zircaloy-2 or the zircaloy-4, difference of the oxygen concentration at the boundary is moderated. Accordingly, the distribution of the oxygen concentration is made more moderate during diffusion of oxygen in the pure zirconium layer. Then, the oxygen concentration at the boundary of the zircaloy is made substantially constant. With such a constitution, the resistance against nodular corrosion due to difference of the two-dimensional boundary condition at the outer surface of the cladding tube can be improved. (T.M.)