Norilsk is currently a so called 'closed city' since 2001, as it is for strategic reasons closed to foreigners. It is believed that these reasons are the huge mineral reserves and mining operations and the IBM-missile depots which are situated in the vicinity of the city.

What happened to Norilsk?

Investigators believe the tank near Norilsk sank because of melting permafrost which weakened its supports. ... The oil contaminated the Ambarnaya river and surrounding subsoil before drifting about 20km (12 miles) north of Norilsk. It then entered Lake Pyasino, which flows to the Kara Sea in the Arctic Ocean.

Can foreigners go to Norilsk?

Because of its strategic importance for nickel ore processing, Norilsk is a closed city and special permission (except for Russian and Belarussian nationals) is needed for travel, which will likely be denied unless you have a really good reason.