Mitigating fuel cladding chemical interactions by enhancing chromium diffusion barrier performance using pulse reverse electroplating

Fuel cladding chemical interaction (FCCI) is a critical issue affecting the safe usage of metallic nuclear fuel in sodium-cooled fast reactors (SFRs). Although a chromium (Cr) coating diffusion barrier has been developed to effectively mitigate FCCI, Cr coatings formed by direct current (DC) and pulse current (PC) electroplating generate hydrogen-induced micro-cracks that reduce diffusion barrier performance. In this study, electroplating with a pulse reverse (PR) current and optimized anodic time was utilized to minimize the effects of hydrogen. Consequently, this approach enabled the formation of a crack-free and highly stable microstructure in the electroplated Cr coating. A diffusion couple test (FCCI test) was conducted at 923 K for 25 h to evaluate that the diffusion barrier performance of the Cr coating formed by DC, PC and PR electroplating. The test results demonstrate the superior diffusion barrier performance of the Cr coating formed by PR electroplating through a systematic analysis comparing the microstructures of Cr coatings formed by different waveforms.