General Purpose Heat Source - Exploded view with english labels

The general-purpose heat source is a U.S. DOE-designed radioactive heat source for radioisotope thermoelectric generators (RTG) or Stirling radioisotope generators (SRG). It is meant for space applications and is packaged as a stackable module.

Characteristics

GPHSs are fueled with plutonium-238 dioxide. Each module has a temperature of over 600 degrees Celsius and delivers 250 watts at the time of manufacture. They measure 9.948 cm wide x 9.32 cm deep x 5.82 cm high and weigh no more than 1.44 kg each.

Safety

GPHSs are designed with safety in mind and employ iridium-clad plutonium-238 dioxide pellets. The generated alpha particles are blocked by the cladding, thus no further radiation shielding is necessary. The pellets are encased within nested layers of carbon-based material and placed within an aeroshell housing to comprise the complete module. The modules can withstand extreme conditions including a launch-pad explosion or a high-speed reentry. Overheating and impact tests were performed on several sample modules.Los Alamos report
General-purpose heat source safety verification test series: SVT-11 through SVT-13
. 1986-05-01, OSTI 5664400. doi:10.2172/5664400

Uses

GPHSs of this, or very similar, design were used in the GPHS-RTGs of Cassini-Huygens,

New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe that was launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research ...

, the Galileo probe, and the Ulysses probe. They are used in the multi-mission radioisotope thermoelectric generator, as used by Mars Science Laboratory (Curiosity rover). They are also used in the

advanced Stirling radioisotope generator The advanced Stirling radioisotope generator (ASRG) is a radioisotope power system first developed at NASA's Glenn Research Center. It uses a Stirling power conversion technology to convert radioactive-decay heat into electricity for use on spacec ...

Stages of assembly

File:Radioisotope thermoelectric generator plutonium pellet.jpg, Plutonium pellet. File:Iridium clad GPHS pellet.jpg, Plutonium pellet within iridium cladding. File:Fueling of the MSL MMRTG 002.jpg, Assembled graphite impact shell. File:Fueling of the MSL MMRTG 001.jpg, Assembled module.

References

Department of Energy (DOE) Office of Nuclear Energy GPHS article

"Radioisotope thermoelectric generators (RTGs)" NASA Galileo Information {{refend

External links

NASA Radioisotope Power Systems website – GPHS overview
Nuclear power in space