Monday, April 7, 2008
"A radioisotope thermoelectric generator (RTG) is an electrical generator which obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples. RTGs can be considered as a type of battery and have been used as power sources in satellites, space probes and unmanned remote facilities. RTGs are usually the most desirable power source for unmanned or unmaintained situations needing a few hundred watts or less of power for durations too long for fuel cells, batteries and generators to provide economically, and in places where solar cells are not viable."
Some RTGs have been used on land (larger scale) to produce power, in Russia for example. Many people have been injured (and possibly even killed) trying to scavenge these in remote locations (places that require compact, portable power), or even sleeping next to them at night to stay warm! I guess the warnings were not good enough.
"In addition to spacecraft, the Soviet Union constructed many unmanned lighthouses and navigation beacons powered by RTGs. Powered by 90Sr, they are very reliable and provide a steady source of power. However, critics argue that they could cause environmental and security problems, as leakage or theft of the radioactive material could pass unnoticed for years (or possibly forever: some of these lighthouses cannot be found because of poor record keeping). There has been even an instance where the radioactive compartments were opened by a thief; it was inferred that the resulting radiation poisoning was fatal. There was also the case of two woodcutters in Siberia who came across one of these units and slept close to it as a heat source during a cold night. They both died of radiation poisoning within a few days afterwards. The unit was eventually recovered and isolated.
There are approximately 1,000 such RTGs in Russia. All of them have long exhausted their 10-year engineered life spans. They are likely no longer functional, and may be in need of dismantling. Some of them have become the prey of metal hunters, who strip the RTGs' metal casings, regardless of the risk of radioactive contamination.
RTGs are also utilized by the United States Air Force to power remote sensing stations for Top-ROCK and Save-Igloo radar systems predominantly located in Alaska."