In addition to spacecraft, the Soviet Union built 1007 RTGs to power uncrewed lighthouses and navigation beacons on the Soviet arctic coast by the late 1980s. Many different types of RTGs were built in the Soviet Union, for a wide variety of purposes. The lighthouses were not maintained for many years after the dissolution of the Soviet Union in 1991. Some of the RTG units disappeared during this time—either by looting or by the natural forces of ice/storm/sea. In 1996, a project was begun by Russian and international supporters to decommission the RTGs in the lighthouses, and by 2021, all RTGs are now removed.