The Mayak Chemical Combine resides in Siberia, in a very picturesque region of the country. However, after years of lax safety at the nuclear facility (which produced the materials for the first Russian nuclear bombs, and now processes spent radioactive fuel from around Europe) the area has been covered in radioactivity. The main safety risks/breaches are as follows:

  • Lake Karachay: In the 50s and 60s nuclear waste was repeatedly and deliberately dumped into this lake, conveniently adjoining the main plant. Too bad that it was seasonally dry, and that unusually strong winds grabbed all of the radioactive sediment and chucked it over parts of Russia. By this point Mayak was putting out more becquerels into the environment over decades than Chernobyl did in one go.
  • Techa River: The Russians also dumped neat nuclear waste into this river, which not only flowed towards the arctic circle and therefore contaminated the unspoilt wilderness of the ice cap, but was also the source of drinking water and a local bathing spot for the village adjoining Mayak, Cheyabilinsk. The net result? Cancer and also plenty of horribly mutated children.
  • Various accidents: Mayak has not been without its fair share of accidents...like that storage tank full of nuclear waste exploding. That's a few more becquerels in the environment then. And that one with the fire...which happened twice. In the same decade.
Mayak is currently in the process of being shut down, for obvious reasons. The Russian government is only just taking notice of the fact that all of its nuclear plants have been involved in some form of safety incident, and that you can't cover up people dying and having deformed children. And you can't silence Greenpeace.
Sources: http://archive.greenpeace.org/mayak
http://www.bellona.com