While claims of up to 2 Million deaths related to Chernobyl[1] are probably not credible, the 6,000 figure is bullshit as well:

The estimates on radioation related deaths of infants is of the same order, and there are Russian claims that 90% of liquidators (at least 747,000 people according to the German Gesellschaft für Strahlenschutz) are invalid.

[1] http://www.scribd.com/doc/50890761/Nuclear-s-Endless-Nightma...