Hiroshima's "Little Boy": the first in history nuclear explosive device used to attack an enemy faction. According to figures published in 1945, 66,000 people were killed as a direct result, and 69,000 were injured to varying degrees. Total amount of nuclear fuel on site: approximately 600 to 860 milligrams of matter. Milligrams! And a big part of that got aniquilated in the explosion.
Chernobil: one nuclear reactor explodes spreading radioactive materials in aerosol form. Total amount of nuclear fuel on site: 180 tonns.
Fukushima: six nuclear reactors, one of them a plutonium reactor, gets severilly damaged after several eathquakes and a tsunami hits the nuclear plant, starts spreading radioactive materials in aerosol form and dumping tonns of contaminated water to the sea. Total amount of nuclear fuel on site: 7,200 tonns.
Call me pesimistic, but I think this is an entirelly different leage, one that may make Chernobil look like a propane gas escape. And I wish I'm wrong...