If this is the same tech I remember, Soviet Russia used them a lot for far-flung lighthouses that couldn't be easily refueled. Many of them are still out there, or have been stolen, vandalized, stripped of metal by unwitting thieves, spreading hazard all around. One was even found underwater.
There is a movie on Netflix streaming that has some small plot feature tied to one of these these nuclear batteries in a far North Russian weather station:
http://www.imdb.com/title/tt1588875/