Part 3 & 4 are best.

On 26 April 1986 01:23:45 a.m., at the Vladimir Ilyich Lenin Nuclear Power Station (Чернобыльская АЭС им. В.И.Ленина), the RBMK reactor of block No.4 suffered a catastrophic failure during a routine test. Only 56 deaths have been "officially" attributed to the disaster, however, documentation shows that well over 600,000 men women and children were directly affected by the fallout. In total, the fallout produced by the exposed burning reactor core would be 400 times greater than the bomb that was dropped on Hiroshima. The deadly toxic molecules were spread across 100's of miles with nearly 60% of the pollutants falling on Belarus. The radioactive plume touched almost every European country including Sweden, Italy, Hungary, The Netherlands, Britain, and France.

It is without question, the biggest nuclear disaster humanity has ever witnessed.