Helical Coil Steam Generator (HCSG) is a specific type of shell and tube heat exchanger known for having a higher heat transfer coefficient than many other designs. For this reason, they are considered in Small Modular Reactor (SMR) and High Temperature Reactor (HTR) designs. Investigation of flow behavior in HTRs is important for better design. To investigate the flow on the shell side, five rod HCSG test section was built in Texas A&M University. Experiments were conducted at Reynolds number of approximately 9000. The spectral element code NEK5000 was used to do high fidelity large-eddy simulation (LES) of the test section to validate against experimental results. In this paper preliminary simulation results were presented. Pressure drop in preliminary results with seventh and ninth order polynomial expansion was consistent with experimental data.