Nuclear Power, because why not?
Well actually because you're building a series of autonomous lighthouses across the North Coast of the Soviet Union, that's why.
Before the collapse of the Soviet Union, leaders of the Communist Party had a problem to solve: how to guide ships through the arctic ocean along its unpopulated northern coast - where polar night envelopes the region for 100 days of the year. Obviously, Solar energy wasn't an option so the Soviets developed an RTG system to power the lights for years at a time - without the need for human interaction!
In an engineering feet, the Soviets building well over 100 of these nuclear lighthouses to safely guide the ships - and their cargo - safely to their destination. Not only would they provide a visual warning to cargo ships but they would also (and this is the cool part) transmit a radio warning of the impending danger captains faced.
After the collapse of the USSR these engineering marvels fell into disrepair, leaking radioactive material into the surrounding areas. Brave (or rather moronic) raiders have also looted the lighthouses for precious metals; apparently unaware of the meaning of "Radioactive Danger."
