Nuclear fuel element

In a nuclear fuel element prepared by containing nuclear fuel pellets in a zirconium lined tube having a zirconium layer lined at the inner circumferential surface of a substrate of a cladding tube made of a zirconium alloy, a means for inhibiting permeation of hydrogen from the zirconium layer to the substrate of the cladding tube is disposed at an intermediate layer portion between both of them. Any of elements may be interposed so long as it has diffusion rate slower than that of hydrogen in Zr in the cladding tube, and at least one of Co, Ni, Cu, and Zn is selected. With such a constitution, stress corrosion cracks are less caused to the cladding tube and hydrogen embrittlement of the substrate of the tube upon rupture of the cladding tube can be prevented. (T.M.)