Cr-Coated Zircaloy Cladding Deformation and Burst Modeling Under LOCA Condition with OFFBEAT

With advancements in nuclear fuel technology, Cr-coated Zircaloy has emerged as a promising candidate for advanced technology fuel (ATF) cladding. This coating demonstrates exceptional corrosion resistance during normal operations and exhibits superior high temperature oxidation resistance and mechanical strength, characteristics critical under design basis accident (DBA) conditions. Following the Fukushima nuclear accident, international research has focused on understanding the behavior of Cr-coated Zircaloy cladding under loss-of-coolant accident (LOCA) scenarios. To accurately predict the performance of Cr-coated Zircaloy cladding, existing fuel performance codes require updates. This study employs the fuel performance code OFFBEAT to analyze Cr-coated Zircaloy cladding. By extending its material models and parameters, thermal and mechanical properties specific to the coated cladding, such as creep of chromium are integrated into the program. The simulations involve the experiment of ORNL in which the Cr-coated Zircaloy cladding has been tested. And another one is an extension for an existing LOCA transient case with a series of coatings with different thicknesses. For the ORNL experiment simulation, the results indicate that the Cr-coating postponed cladding burst time, reduces the rate of stress increase, but it seems also make the cladding more sensitive to stress. By comparing simulation results of different thickness coating, Cr-coating shows the ability to restrain cladding deformation, but the yield of Cr should be considered more carefully.