Originally built for use in the 1930’s by Japan, it was later seized by Russians and used during World War II, powered by nuclear power. During the 1990’s and the fall of communism, the lighthouse became vacant and has since been abandoned.
More on https://mentalitch.com/spooky-russian-places-aniva-rock-lighthouse-sakhalinskaya-oblast/
or https://www.rbth.com/travel/334968-abandoned-aniva-lighthouse-nakashiretoko
It's a Radioisotope Thermoelectric Generator, aka a "nuclear battery". It's stable and safe and only uses a small amount of plutonium (of a type that isn't useful for making bombs). They're so reliable that they use RTGs for spacecraft like Voyager and Cassini.
I know about riteg, but not during ww2