Nickel plated Zircaloy-4 tubing (“getter tubing”) is an important functional component in Tritium
Producing Burnable Absorber Rods (TBPARs). Getter tubes are used to capture tritium produced during
reactor operations and convert it from a gas to a solid by reacting it with Zr to form ZrHx compounds.
Previous studies (PNNL-27232, TTP-8-004, and TTP-30710) on forming Zircaloy-4 hydrides
demonstrated that hydride concentration gradients formed under prototypic hydriding conditions and that the microstructure of hydrides formed at 350°C is different than those formed at 500°C, a temperature typically used by the Tritium Technology Program (TTP) for getter rate loading experiments.
Differences in hydride distribution, microstructure, and phases were characterize using scanning electron microscopy methods. However, the impact of these differences on material properties is not well understood. The goal of this project was to determine whether atomic force microscopy could observe subtle differences in material properties of single domains of hydride phases formed in Zircaloy-4. These properties include surface structure, hardness, thermal conductivity, and magnetic susceptibility.