...Nuclear power is uniquely unforgiving: as Swedish Nobel physicist Hannes Alfvén said, "No acts of God can be permitted." Fallible people have created its half-century history of a few calamities, a steady stream of worrying incidents, and many near-misses. America has been lucky so far. Had Three Mile Island's containment dome not been built double-strength because it was under an airport landing path, it may not have withstood the 1979 accident's hydrogen explosion. In 2002, Ohio's Davis-Besse reactor was luckily caught just before its massive pressure-vessel lid rusted through.
Regulators haven't resolved these or other key safety issues, such as terrorist threats to reactors, lest they disrupt a powerful industry. U.S. regulation is not clearly better than Japanese regulation, nor more transparent: industry-friendly rules bar the American public from meaningful participation. Many presidents' nuclear boosterism also discourages inquiry and dissent.
Nuclear-promoting regulators inspire even less confidence. The International Atomic Energy Agency's 2005 estimate of about 4,000 Chernobyl deaths contrasts with a rigorous 2009 review of 5,000 mainly Slavic-language scientific papers the IAEA overlooked. It found deaths approaching a million through 2004, nearly 170,000 of them in North America. The total toll now exceeds a million, plus a half-trillion dollars' economic damage. The fallout reached four continents, just as the jet stream could swiftly carry Fukushima fallout.
Fukushima I-4's spent fuel alone, while in the reactor, had produced (over years, not in an instant) more than a hundred times more fission energy and hence radioactivity than both 1945 atomic bombs. If that already-damaged fuel keeps overheating, it may melt or burn, releasing into the air things like cesium-137 and strontium-90, which take several centuries to decay a millionfold. Unit 3's fuel is spiked with plutonium, which takes 482,000 years.
Nuclear power is the only energy source where mishap or malice can...
http://www.greentechmedia.com/articles/read/guest-post-learning-from-japans-nuclear-disaster/