Nuclear fuel elements

Purpose: To increase the stress corrosion cracking resistance. Constitution: A hollow billet is prepared by melting pure zirconium material into an ingot followed by casting and molding. The hollow billet is inserted into a separately formed hollow billet, for example, made of a zirconium alloy such as zircaloy-2. The joined two hollow billets are hot-extruded to form a zirconium liner cladding tube comprising pure zirconium at the inside and zirconium at the outside. The tube is repeatedly subjected to cold rolling and annealing for a predetermined number of cycles to obtain a zirconium liner cladding tube with carbon content of less than 50 ppm by weight. The cladding tube having the carbon content of less than 50 ppm by weight in zirconium causes less crackings even applied with inner pressures in an atmosphere, for example, at high temperature thereby enabling to prevent stress corrosion crackings. (Seki, T.)