Radioisotope power systems (RPSs) convert the heat from the decay of the radioactive isotope plutonium-238 (Pu-238) into electricity. RPSs are capable of producing heat and electricity under the harsh conditions encountered in deep space for decades.

They have proven safe, reliable, and maintenance-free in missions to study the moon and all of the planets in the solar system except Mercury. The RPS-powered New Horizons spacecraft transited the Pluto system on July 14, 2015, and will continue on to explore other objects in the Kuiper belt.

SST maintains the infrastructure to develop, manufacture, test, analyze, and deliver RPSs for space exploration and national security missions. SST provides two general types of systems – power systems that provide electricity, such as radioisotope thermoelectric generators (RTGs), and small heat sources called radioisotope heater units (RHUs) that keep spacecraft components warm in harsh environments.

SST also maintains responsibility for nuclear safety throughout all aspects of the missions and performs a detailed analysis in support of those missions.

SST has successfully accomplished nuclear power system missions by maintaining a unique set of capabilities through highly skilled engineers and technicians and specialized facilities at SST national laboratories. Oak Ridge National Laboratory provides unique materials and hardware. Plutonium-238 is purified and encapsulated at Los Alamos National Laboratory.

Idaho National Laboratory assembles the encapsulated fuel into a heat source designed to contain the fuel in potential accident situations, integrates the heat source and power conversion system into the final power system, and assures their final delivery. SST maintains unique shipping containers and trailers to safely transport components and power systems across the SST complex and to user agencies.

SST also maintains the unique ability to evaluate and characterize the safety of these systems. Sandia National Laboratories leads the development and maintenance of the required analytical tools, database, and capabilities. Power system design, development, manufacturing, and non-nuclear testing are performed by competitively selected system integration contractors.

The Office of Advanced Reactor Technologies (ART) sponsors research, development and deployment (RD&D) activities through its Next Generation Nuclear Plant (NGNP), Advanced Reactor Concepts (ARC), and Advanced Small Modular Reactor (aSMR) programs to promote safety, technical, economical, and environmental advancements of innovative Generation IV nuclear energy technologies.

The Office of Nuclear Energy (NE) will pursue these advancements through RD&D activities at the Department of Energy (DOE) national laboratories and U.S. universities, as well as through collaboration with industry and international partners.

These activities will focus on advancing scientific understanding of these technologies, establishing an international network of user facilities for civil nuclear RD&D, improving economic competitiveness, and reducing the technical and regulatory uncertainties for deploying new nuclear reactor technologies. International collaborations are conducted through bilateral and multilateral agreements, including through the Generation IV International Forum.

The Advanced Reactor Concepts (ARC) program supports the research of advanced reactor subsystems and addresses long-term technical barriers for the development of advanced nuclear fission energy systems utilizing coolants such as liquid metal, fluoride salt, or gas.

• Research on innovative technologies that resolve key feasibility and performance challenges.

• Research on innovative technologies that reduce fabrication, construction and operating costs.

• Exploration and development of supercritical CO2 Brayton thermal cycle for diverse reactor applications that couple nuclear reactors to power generation with much improved conversion efficiency and reduced plant size.

• Enable, through research, additional long-term nuclear energy options that have the potential to provide significant safety, economic improvements and lower fabrication, construction and operations costs.

• Utilize international collaborations to leverage and expand R&D investments.

The key R&D needs are being addressed for advanced concepts at different maturity levels: liquid metal-cooled fast reactors, including sodium-cooled fast reactors (SFRs), and fluoride salt-cooled high-temperature reactors (FHRs). The ARC program is expanding engagement with industry by use of the Technical Review Panel (TRP) process in which viable reactor concepts are evaluated by reactor experts in order to identify R&D needs of advanced concepts and help inform DOE R&D investment decisions.

The program supports international collaboration through bilateral engagement and multilateral arrangements such as the in the Generation IV International Forum and the Sodium Fast Reactor trilateral arrangement.

This program will be focused on high value research for long term concepts, R&D needs for promising mid-range concepts, the development of innovative technologies that benefit multiple concepts and stimulation of new ideas for transformational future concepts.