Radioisotope thermoelectric generator

Radioisotope thermoelectric generator (RTG) is a type of nuclear power generator that uses an array of thermocouples to convert the radioactive decay heat of a suitable radioisotope into electricity by the Seebeck effect. This type of generator has no moving parts.

RTGs have been used as power sources in satellites, space probes, and unmanned remote facilities such as a series of lighthouses built by the former Soviet Union inside the Arctic Circle. RTGs are usually the most desirable power source for unmanned or unattended systems that need a reliable, long-lived power source, such as spacecraft, remote sensing, telemetry and long-range unmanned aircraft.

History

The concept of RTGs was first proposed by Moe Berg, a professional baseball player and spy during World War II. The first RTG was developed by the U.S. Atomic Energy Commission in the late 1950s.

Design and function

The design of an RTG is simple and robust with few moving parts. A general-purpose heat source (GPHS) module contains four plutonium-238 fuel pellets, a iridium alloy shell, and several layers of graphite material to prevent the escape of the fuel. The heat generated by the decay of the fuel is converted into electricity by thermocouples.

Applications

RTGs have been used in several space missions, including the Voyager missions, the Galileo spacecraft, the Cassini spacecraft, and the New Horizons spacecraft. They are also used in remote terrestrial applications, such as powering lighthouses in the former Soviet Union.

Safety and disposal

The safety of RTGs is a concern due to the radioactive materials they contain. However, the design of the RTGs is such that they are safe under all conceivable accident conditions. The disposal of RTGs is regulated by international agreements and involves safe storage until the radioactivity has decayed to safe levels.

See also

• Nuclear power
• Thermoelectric effect
• Radioactive decay
• Spacecraft propulsion

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Radioisotope thermoelectric generator gallery

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  Cutdrawing of an GPHS-RTG

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  Radioisotope thermoelectric generator plutonium pellet

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  Soviet RTG

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  RTG module

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  ALSEP Apollo 14 RTG (cropped)