In this work, a simulation is presented that plays an important part in estimating the characteristics of cooling in a blanket used for high-temperature plasma in a fusion reactor. The objective of this study is to perform a large-scale direct numerical simulation (DNS) on the heat transfer of turbulent flow of the coolant materials assumed gas flow. The coolant flow conditions in a fusion reactor are assumed to be defined by a Reynolds number of a higher order. To investigate the effect of Reynolds number on the scalar structures, the Reynolds number based on a friction velocity and a pipe radius was set to be Reτ = 1050. The numbers of the computational grid points used for Reτ= 1050 were 2048 × 512 × 768 in the z−, r−, and ϕ-directions, respectively. In this work, details on the turbulent quantities such as the mean flow, turbulent stresses, turbulent kinetic energy budget, and the turbulent statistics were obtained.