Wednesday, March 23, 2011

Nuclear Power and Relative Risk

A commenter on one of my recent posts said that "Every human enterprise involves some risk". This is the same message as a March 14th Wall Street Journal opinion article. In light of the ongoing Fukushima crisis, I think it's instructive to review the concept of relative risk.

Just looking at the statistics, I think the most obvious lesson of the Tōhoku earthquake and the resultant tsunami (i.e., the disasters that caused the Fukushima accident) is that it's more dangerous to live by the beach than it is to live by a nuclear plant. The earthquake and the tsunami (which caused most of the casualties) left a death-toll of around 10,000 people, while the nuclear accident has not officially killed anybody (although two workers are missing who may have been killed in an explosion). Yet the lesson that so many anti-nuclear activists and ordinary Americans will take away from the disaster is not that beachfront property may be a poor investment, but that nuclear power is dangerous and bad. In fact, even in light of the 230,000+ deaths caused by the 2004 Indian Ocean tsunami, I think most people would still like to own a home by the ocean.

Three Mile Island
I am always amazed by how risk-averse Americans are with regards to some things while having absolutely no trepidation about other things that are much more likely to kill or injure them. For example, nuclear power is one of those touchy subjects that causes panic or fear in millions of Americans. Yet the total number of Americans that have been demonstrably killed by nuclear power (not counting a handful of early incidents involving experimental bomb cores) is three. That's right; three people, all of whom were military personnel killed in the explosion of the experimental SL-1 reactor in 1961. One study suggests that one or two cancer deaths may have occurred after the Three Mile Island accident, but this number was determined statistically and cannot be confirmed. Worldwide there have only been 63 confirmed fatalities directly associated with nuclear power (this number omits weapons and military related incidents as well as the Fukushima crisis, which isn't quite finished yet).

The Chernobyl disaster, which was caused by a poorly designed reactor and an ill-advised experiment that disabled essential safety systems, accounts for the bulk of the fatalities (53 out of the 63). However, it must be admitted that the official figure may be misleading since the Soviet Union was never known for releasing honest casualty figures. Shortly after the accident, the United Nations Scientific Committee of the Effects of Atomic Radiation (UNSCEAR) estimated that 4,000 people would suffer from cancer due to the accident (later reports suggested that this was an overestimate). Not all of these 4,000 people would have died prematurely since some types of cancer associated with radiation exposure (e.g., thyroid cancer) are relatively treatable and have a decent survival rate.

To prove my point about relative risk, let's begin by approximating how many people may have been killed by nuclear power. Since I couldn't possibly guess how effective Soviet medicine was in the 1980s, we'll just count all 4,000 potential cancer cases caused by Chernobyl as fatalities. Thus, an upper limit of 4,063 people may have been killed by nuclear plant accidents since 1961, with the vast majority of that number being questionable. If we divide that number by 57 years (the number of years that have passed between now and 1954, when the first nuclear reactor to provide power for an electrical grid came online) we end up with an average number of approximately 71 deaths per year due to nuclear power plants. Remember, this number was boosted by an estimated number of cancer cases that might have been incurred by the Chernobyl disaster. If we only use confirmed numbers then the average number of deaths per year drops to about 1.

A lot more deadly than any nuclear reactor
Using the exaggerated number of 71 deaths per year, it becomes horribly ironic that most anti-nuclear activists protesting at a nuclear power plant must have driven there. Every year around 30,000 to 40,000 Americans are killed in auto accidents. It is estimated that a worldwide total of 1.2 million people are killed annually in auto accidents. This means that, on average, nearly 17,000 times more people die annually in car accidents than in nuclear plant accidents. Clearly we're in the middle of an automobile-spawned apocalypse. So where are the anti-automobile activists?

Electricity: Threat or menace?
How about an energy source that we interact with daily? In 1993 550 people were killed by electricity in the United States. Given that US electrical safety standards are significantly higher than they are in parts of the developing world, the number of electrical fatalities worldwide is undoubtedly much higher. Either way, this number is almost eight times higher than our average annual rate of nuclear power-related deaths (this assumes that 550 is a fairly representative fatality rate for more recent years). Honestly, how can we even allow electricity into our homes when it's clearly so dangerous?

Windmills of DEATH
While we're throwing numbers around, it turns out that accidents involving wind power have killed 73 people between 1975 and 2010. Note that this number of fatalities (which were incurred over a period of 35 years) exceeds the 63 officially confirmed deaths caused by nuclear plant accidents (after 57 years of commercial nuclear power). The most common cause of windmill related accidents was blade failure. When a turbine blade fails, the blade or pieces of the blade can be thrown at a lethal velocity. Now that wind turbines are being built in ever greater numbers and closer to inhabited areas, we can only expect the number of accidents to go up. Too bad all those activists are too busy protesting nuclear plants to care about the windmill farms being built near residential areas.

Don't breathe too deep
Now that we're back on the subject of electricity production, let's talk about coal-produced power. In 2006 coal plants generated about 49% of America's electricity and 68.7% of China's electricity (nuclear power accounts for about 20% of US electricity). Ironically, because coal contains a number of naturally radioactive isotopes, it is estimated that US coal burning in 1982 released 155 times more radioactivity into the air than the Three Mile Island accident. Ignoring the effect of radioactivity, we find reports suggesting that 750,000 Chinese die prematurely each year due to air pollution. The World Health Organization has claimed that 2.4 million die each year due to air pollution. Much of this pollution comes from burning coal for electricity. Now, I know that there are anti-coal plant activists, but many of them are the kind that conveniently forget that coal power is a major source of the energy used to make solar cells, manufacture wind turbines, or to charge their "environmentally friendly" Chevy Volts. Modern life (which is more than 20 years longer and healthier than life in the early 20th century) would not be possible without the electricity produced by burning coal.

The point I'm trying to make is that human life is full of risks but that many people seem to be confused about what risks they should worry about. Even if the Fukushima accident turns out as bad as the most extreme estimates suggest (estimates which are almost invariably developed by anti-nuclear organizations), the number of deaths that could be caused by radiation sickness and radiation-induced cancer would be far exceeded by the number of auto deaths that occur in the United States in a single month. Yet most of the Americans who are stocking up on iodine tablets probably don't think twice about getting into a car (and I'd bet a good percentage of them don't even bother to put on a seatbelt). Although I spend every work day in close proximity with nuclear materials and energy, I know that the most dangerous part of my day is the drive to and from work.

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