Large Eddy Simulations of scaled HTGR lower plenum for assessment of turbulent mixing

•Large Eddy Simulations are conducted of unit cell from HTGR lower plenum.•Average and fluctuating temperatures are quantified on the surface of each post.•Jet to cross flow velocity ratio and unit cell orientation dictate thermal loads.•Large crossflow velocity reduces variance of surface temperature signals.•Impact of downstream recirculation region is stronger when crossflow is reduced.