FCCI barrier performance of electroplated Cr for metallic fuel

As the fuel-cladding chemical interaction (FCCI) between metallic fuel and cladding material can occur at a relatively low temperature, electroplating of Cr as an FCCI barrier on the inner wall of the cladding was proposed. U–10 wt.%Zr and HT9 disks were used as fuel and cladding material to conduct diffusion couple annealing tests at 740 and 800 °C. Two kinds of Cr layers dependent on the temperature of plating bath were electroplated on the surface of the HT9 disks. The Cr layer of 20 μm in thickness, after being electroplated at a bath temperature of 50 °C and a current density of 35 A/dm2 for 1 h, had some cracks and a small-grained structure. However, the Cr layer plated at a bath temperature of 80 °C and a current density of 56 A/dm2 for 2 h showed a dense structure. Both Cr layers inhibited the interaction between U–10 wt.%Zr and HT9 at a relatively high annealing temperature. U penetrated into the Cr layer plated at a bath temperature of 50 °C due to its penetrable structure. The Cr layer plated at a bath temperature of 80 °C showed a better performance than the Cr layer plated at a bath temperature of 50 °C as a diffusion barrier material with less U penetration.