Title: Nuclear Reactors for Space - World Nuclear Association
Headings: Nuclear Reactors and Radioisotopes for Space
Nuclear Reactors and Radioisotopes for Space
Radioisotope systems – RTGs
Fission systems – heat and propulsion
Early US programme: 1960s to 1980s
Later US programmes: 1990s on
US Project Prometheus: 2003-2007
Current US programme
Russian fission systems
Space Reactor Power Systems
Radiation in space
Notes & references
General sources
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Content: The United Nations has an Office for Outer Space Affairs (UNOOSA)* which implements decisions of the Committee on the Peaceful Uses of Outer Space (COPUOS) set up in 1959 and now with 71 member states. UNOOSA recognises “that for some missions in outer space nuclear power sources are particularly suited or even essential owing to their compactness, long life and other attributes” and “that the use of nuclear power sources in outer space should focus on those applications which take advantage of the particular properties of nuclear power sources.” It has adopted a set of principles applicable “to nuclear power sources in outer space devoted to the generation of electric power on board space objects for non-propulsive purposes,” including both radioisotope systems and fission reactors. * UNOOSA has the dual objective of supporting the intergovernmental discussions in the Committee and its Scientific and Technical Subcommittee (S&T) and Legal Subcommittee, and of assisting developing countries in using space technology for development. In addition, it follows legal, scientific and technical developments relating to space activities, technology and applications in order to provide technical information and advice to Member States, international organizations and other United Nations offices. Radioisotope systems – RTGs
Radioisotope Thermoelectric Generators (RTGs) have been the main power source for US space work since 1961. The high decay heat of Plutonium-238 (0.56 W/g) enables its use as an electricity source in the RTGs of spacecraft, satellites and navigation beacons. Its intense alpha decay process with negligible gamma radiation calls for minimal shielding. Americium-241, with 0.15 W/g, is another source of energy, favoured by the European Space Agency, though it has high levels of relatively low-energy gamma radiation. Heat from the oxide fuel is converted to electricity through static thermoelectric elements (solid-state thermocouples), with no moving parts.