The Mayak Production Association is a nuclear facility near Ozyorsk, Chelyabinsk Oblast, Russia, with production reactors and a reprocessing plant. Its reprocessing capacity, at 400 tonnes of heavy metal per year, is the second-largest in the world, following the La Hague site in France. It is currently used for military and civilian radioisotope production, and was historically central to the Soviet nuclear weapons program.