Media coverage of the Japan nuclear reactor leak makes it seem like the worst kind of power plant disaster that you would ever face. But when you look at the actual statistics and history of similar disasters, nuclear power plants are not the most dangerous energy sources - even when terrible accidents happen.
The disaster in Japan is horrific, and we aren't trying to say it isn't a terrible situation. The question we're trying to answer rationally here is whether nuclear power plant accidents cause more damage than other kinds of power plants. We've put together a list of five of the worst power plant disasters in recent history, measured by death toll, monetary damage, and regions affected. The lesson? The issue isn't so much the kind of energy you use, but how you design the power plants that contain it.
As you can see, when accidents happen, the deadliest and costliest source of energy is water - especially when it's held back by poorly-designed dams. The Chernobyl disaster doesn't come close to the damage done when a dam at a hydroelectric plant bursts.
Oil and natural gas are among the most expensive energy sources in terms of damage done.
In addition, we have only measured the cost to human life here. The Kingston Fossil Plant coal fly ash slurry spill and the Deepwater Horizon oil spill - both enormously expensive oil industry disasters - destroyed enormous amounts of wildlife on land and in the water, even if the human toll was low.
1975: Shimantan/Banqiao Dam Failure
Type of power: Hydroelectric
Human lives lost: 171,000
What happened: Shimantan Dam in China's Henan province fails and releases 15.738 billion tons of water, causing widespread flooding that destroys 18 villages and 1500 homes and induces disease epidemics and famine
1979: Morvi Dam Failure
Type of power: Hydroelectric
Human lives lost: 1500 (estimated)
What happened: Torrential rain and unprecidented flooding caused the Machchu-2 dam, situated on the Machhu river, to burst. This sent a wall of water through the town of Morvi in the Indian State of Gujarat.
1998: Nigerian National Petroleum Corporation Jess Oil Pipeline Explosion
Type of power: Oil
Human lives lost: 1,078
What happened:Petroleum pipeline ruptures and explodes, destroying two villages and hundreds of villagers scavenging gasoline.
1944: East Ohio Gas Company
Type of power: Liquified natural gas (LNG)
Human lives lost: 130
What happened: Explosion at LNG facility destroys one square mile of Cleveland, OH.
1907: Monongah Coal Mine
Type of power: Coal
Human lives lost: 362
What happened: Underground explosion traps workers and destroys railroad bridges leading into the mine.
Compare these to:
1986: Chernobyl Nuclear Power Plant
Type of power: Nuclear
Human lives lost: 4,056 (Source for this number: United Nations Scientific Subcommittee on the Effects of Atomic Radiation)
What happened: Mishandled reactor safety test at Chernobyl nuclear reactor causes steam explosion and meltdown, necessitating the evacuation of 300,000 people from Kiev, Ukraine and dispersing radioactive materials across Europe.
NOTE: Monetary damage is measured in 1996 US dollars, except in accidents since that time measured in the dollar values of that year.
A lot of this research was based on public policy professor Andrew Sovacool's extremely informative monograph "The Accidental Century," which looks at power plant disasters in the twentieth century in great detail. Another good resource is this 1998 report from PSI, a Swiss engineering institute, which (as Robert Gonzalez points out in comments) explores the risks of various power systems as well as the long-term effects of accidents in the energy industry.