Modular Integrated Gas High Temperature Nuclear Reactor

A high temperature gas reactor includes components which are horizontally laid out, the components including a steam generator module, a core module, and a control rod unit. The components can be supported by rollers on rails facilitating assembly and alignment. The components can move on rails in a common line in space. The components each can have flanges enabling fastening of the modules to one another. The components can slide along the rails individually and as a unit with the components are fastened together. The rails facilitate alignment and mounting of components.