Composite cladding tubes for nuclear fuels

Purpose: To suppress the stress corrosion crackings and improve the reliability of a cladding tube by making the metal barriers with an alloy of zirconium and tin. Constitution: In a composite cladding tube in which a metal barrier is disposed to the inner surface of a cladding tube comprising a zirconium alloy for coating nuclear fuel pellets, pure zirconium used so far as the zirconium liner layer violently reacts with water at a temperature above about 500 deg C to form oxides and also generates a great amount of hydrogen gas. Such a phenomenon includes a possibility of generating a great amount of hydrogen thereby bringing the reactor core into dangerous state in the case if water intrudes to the inside of the cladding tube under the high temperature state such as upon coolant accidents. In view of the above, by making the metal barrier with an alloy of zirconium and tin, favorable corrosion resistance can be provided even if the high temperature water flows to the inside. (Takahashi, M.)