Development of Diffusion Barrier Coatings for Mitigation of Fuel-Cladding Chemical Interactions

Abstract

Fuel Cladding Chemical Interactions (FCCI) in a nuclear reactor occur due to thermal and radiation enhanced inter-diffusion between the cladding and fuel materials, and can have the detrimental effects of reducing the effective cladding wall thickness and the formation of low melting point eutectic compounds. Deposition of diffusion barrier coatings of a thin oxide on the inner surface of the cladding can potentially reduce or delay the onset of FCCI. This study examines the feasibility of using nanofluid-based electrophoretic deposition (EPD) process to deposit coatings of titanium oxide, yttria-stabilized zirconia (YSZ) and vanadium oxide. The deposition parameters, including the nanofluid composition, current, and voltage were optimized for each coating material using test flat substrates of T91 ferritic-martensitic steel. Diffusion characteristics of the coatings were investigated by diffusion couple experiments using the fuel surrogate cerium. These diffusion couple studies performed in the temperature range of 560°C and 585°C showed that the oxide coatings significantly reduce the solid state inter-diffusion between cerium to steel.

Reducing fuel-cladding chemical interaction: The effect of palladium on the reactivity of neodymium on iron in diffusion couples

“…Fission product lanthanides are known to be a major cause of FCCI in fast reactors. Although several methods, such as coatings or foil barriers have been tested [1][2][3][4][5], an alternative is proposed whereby an additive dopant is used to chemically bind the lanthanides as intermetallic compounds. This study provides evidence that palladium-neodymium intermetallic compounds, in direct contact with iron, will mitigate this interaction.…”