|Russian RTG for lighthouses and abandoned navigation beacons|
In the Russian far north and Siberia, the Soviet Union equipped about a thousand beacons and uninhabited lighthouses with thermoelectric generators called RTG. These RTGs use the energy of radioactive decays of strontium-90, a radioisotope much cheaper than plutonium-238, but less efficient. These generators well over 10 years of operation were often left abandoned. Scrap merchants, who unaware of the risks of radioactive contamination, sought to retrieve the metal casings, have vandalized some of them.