This technical report provides a design criteria for a technical support facility for the Lithium Cooled Reactor Experiment (LCRE) and SNAP-50-DR-1 Test Facilities. The support facility is adjacent to the LCRE Test Facility and is located completely within the existing Building 629 structure at the former ANP area of the National Reactor Testing Station (NRTS) near Idaho Falls, Idaho. The information and specifications presented establish the basis for the design of laboratories, shops and engineering areas required to support the installation, operation, maintenance and disassembly of the LCRE and SNAP-50 tests. The construction and modification required to adapt the building to reactor test support operations are described in detail in the following report.