In 2003, the Department of Energy (DOE) provided a report to Congress describing DOE’s Generation IV nuclear energy systems implementation strategy1. That report indicated two priorities for Generation IV development. The first priority was to develop a more economically competitive system to meet growing energy demand and maintain the share of nuclear energy in the United States. To achieve this objective, the program has focused on developing a Very High Temperature Reactor (VHTR)-based system that is designed to produce cost-effective electricity, and which offers the potential to produce hydrogen. The second priority was to develop a fast spectrum reactor to further close the nuclear fuel cycle. Three fast reactor concepts have been under development as part of the Generation IV Program.