with top-secret nuclear research, though this is more properly applicable to Chelyabinsk Oblast as a whole, as nuclear facilities such as Chelyabinsk-70 (Snezhinsk) are, or were, located far outside the city. A serious nuclear accident occurred in 1957 at the Mayak nuclear fuel reprocessing plant, 150 km north-west of the city, which caused deaths in Chelyabinsk Oblast but not in the city. The province was closed to all foreigners until 1992 other than a British medical team following a two train rail explosion in the mid 1980s
