The aim of this project is to develop a multiphysics model of a HTGR gas turbine power station. Particular attention will be paid in selection of Printed Circuit Heat Exchanger (PCHE) design as well as working fluid. The study will investigate performance of various geometry of heat exchanger aligned with working fluid. Different shape of channels as well as various working fluids become interesting challenges to be analysed. Thermal energy optimisation from selected PCHE and working fluid and Closed Brayton Cycle matching is another challenge. The final goal of this research is a multiphysics model for HTGR gas turbine power plant with the best PCHE and working fluid performance.