Diffusion barrier properties of nitride-based coatings on fuel cladding

In this work, titanium nitride (TiN) and zirconium nitride (ZrN) coatings are proposed as diffusion barriers between stainless steel nuclear fuel cladding and lanthanide fission products. TiN and ZrN have been coated as barrier materials between pure Fe and Ce, i.e. diffusion couples of Fe/TiN/Ce and Fe/ZrN/Ce, annealed up to a temperature of 600 °C, and compared to the diffusion behavior of uncoated Fe/Ce. Backscattered electron images and energy dispersive X-ray spectroscopy measurements confirm that, with a 500 nm TiN or ZrN layer, no obvious diffusion is observed between Fe and Ce. Basic diffusion characteristics of the Fe/Ce couple have also been measured and compared with the TiN and ZrN coated ones. These preliminary results strongly advocate that TiN and ZrN coatings may be feasible as diffusion barriers against Ce and possibly other lanthanide fission products.