Research on Nickel-Plated Hydrogen-Absorption Device in Fuel Rod and Performance Testing

The hydrogen may be introduced into the fuel rod during the process of production and manufacture. During the operation in reactor, the irradiated fuel pellets also produce radioactive isotopes of hydrogen and tritium. Under the operating condition in pile, the hydrogen in fuel rod will enter the zirconium alloy cladding tube forming hydride, lead to the hydrogen brittleness of cladding tube, and severe cases can lead to the cladding tube broken. The radioactive tritium inside fuel rod has high activity, and it possibly goes through the cladding tube by diffusion penetration into the reactor coolant. With the reactor in waste water or steam waste emissions to the environment, such as lead to tritium radiation safety problems of environmental pollution. Thus, reduce the hydrogen source and tritium pressure in fuel rod, is the way to reduce the hydrogen absorption effect and the release of tritium to coolant. By conducting the Zr-4 alloy nickel-plated hydrogen-absorption device design research, through nickel plating process on the surface of Zr-4 alloy structure parts, eliminating the influence of the oxide film to maintain its excellent absorbing hydrogen isotope activity. During the design operating temperature conditions of fuel rods, the reaction of zirconium hydride has lower hydrogen balance pressure, while the gas cavity kept low pressure hydrogen isotope, can significantly reduce the hydrogen pickup of fuel rod zirconium alloy cladding tube and reduce the tritium permeation emissions by cladding tube. Through nickel-plated hydrogen-absorption device structure design, manufacture, performance testing, analysis and evaluation, demonstrates that the flat plate and cross nickel-plated hydrogen-absorption device can meet the expected effect.