Silver diffusivity measurement in ZrC with SIMS to study the release behavior of 110mAg for nuclear fuel applications

Abstract

Recently, the diffusion coefficient of silver (Ag) in zirconium carbide (ZrC) at 1500 °C was determined to help elucidate the diffusive behavior of radioactive 110mAg in the ZrC coating of the tri-structural isotropic (TRISO) nuclear fuel particle. This study was conducted using a recently developed diffusion experimental technique, known as the encapsulating source method. To verify the validity of this experimental method, modifications to the original experimental design have been made within the domain of this method. Primarily, the ability to retrieve the ZrC disk made it possible to create depth profiles using secondary ion mass spectrometry (SIMS) for more precise depth profiling of Ag concentration in ZrC. Applying this improved experimental design, a sample was fabricated and diffusion annealed at 1500 °C for 2 h. Finally, silver concentrations on the ZrC disk were measured using SIMS. Consequently, the diffusion coefficient of Ag in ZrC0.95 at 1500 °C was experimentally determined to be about 1.7 × 10−17 m2/s, remarkably consistent with the previously reported value of 2.8 × 10−17 m2/s, also obtained by means of the encapsulating source method. This proves that the encapsulating source method is a reliable experimental technique to determine the Ag diffusivity in ZrC.