Among various hydrogen production methods, such as steam methane reforming and thermochemical water splitting, the copper-chlorine thermochemical cycle is an advanced method to produce hydrogen that can help achieve sustainable development and clean energy systems. The cycle requires large amounts of heat as the main energy input, and using nuclear heat is a promising option for reducing emissions of greenhouse gases and other pollutants. An investigation is reported of an analysis of an intermediate high-pressure shell and tube heat exchanger using FLUENT software. The RNG k–ɛ turbulence model is adopted for modeling turbulent flow. In this study, the flow field and the characteristics of a shell and tube heat exchanger for heat extraction from supercritical water-cooled nuclear reactors (SCWRs) to the heat transfer fluid that serves as the heating fluid in a hydrogen production process based on the copper-chlorine thermochemical water decomposition cycle are investigated. The results show that the heat transfer is improved by increasing the operating pressure, although higher pressure drops also occur in the heat exchanger in such instances. Also, the effects of using baffles and various baffle arrangements are studied.