The Chernobyl disaster occured when a nuclear reactor blew up causing 100 atomic bombs worth of radioactive smoke and material to be thrown out into the air.
There is a also a great discovery channel documentary in Russian on the peer 2 peer networks. I didn't know the spread of the radiation was so massive. Just search "Chernobyl Spread" on google images.
A large radioactive mass lies within chernobyl.
Thyroid cancer rates are about double in effected areas. Thyroid cancer is the one most reported but there has been many other ailments caused by high radioactivity levels. It's only been 20 years. Perhaps after a century we'll be able to analyze the more subtle effects as it relates to offspring.
Google Video search and Youtube bring up tons of results. There are a few from green peace and for some reason, free energy conspiracy promoters. Chernobyl's nuclear program also was done with time pressure from the Russian government so that played a huge role. I'm pretty ignorant about the technical requirements to ensure a safe nuclear power plant and the odds of it blowing up within 100 years, so I can't speak for or against nuclear energy.