The SNAP-10A reactor is a high-temperature, liquid metal cooled reactor designed for satellite and other space applications. The reactor is an integral part of the SNAP-10A system, which is a self-contained power unit producing a minimum of 500 watts electrical. The SNAP-10A reactor structure has been designed to withstand a multitude of environmental conditions, including launch and operational loads, space vacuum, meteoroids, high temperature, nuclear irradiation, and liquid metal corrosion. Other design considerations were fabricability and nuclear, thermal, and mechanical compatibility with the rest of the SNAP-10A system. The validity of the SNAP-10A reactor design has been proven by a comprehensive series of nuclear and environmental tests on both a component and system basis.