This is the result of a comment I left on Hacker News a while ago, which I thought might be worth expanding into a blog post. We all know about the disaster at the Fukushima nuclear plant, and probably heard about all the many things that have gone wrong there. I've often seen people use Fukushima as an example of why nuclear power is too dangerous for us to use, and that we have to move to other methods of generating electricity. Some people have claimed that Germany is replacing their nuclear power generation with Coal after Fukushima, while others says that that's wrong and Germany is merely replacing Nuclear with renewables when it would otherwise have replaced coal with the growth in it's use of coal being merely incidental.
But at the same time, how things get talked about by the media is often a poor guide to how dangerous things really are in practice. So bad was the Fukushima disaster, really? The Tsunami that hit Japan was a humongous disaster, killing well over 15,000 people by itself. Clearly we can't blame those deaths on the nuclear disaster, though. Nobody died from radiation poisoning as a result of the Fukushima disaster, but with something like this most of the damage is in the form of people developing and dieing from cancer potentially many years later. A WHO study of those effected by the disaster looked for changes in the incidence of cancer in people affected by the disaster but couldn't find any. But that merely puts a ceiling on the strength of the effects since it might be that not enough people have yet gotten cancer from the disaster to be statistically significant in the WHO study. Another study by Hoeve and Jacboson estimated around 120 excess deaths from cancer caused by the Fukushima disaster.
Now, there are also other deaths associated with the disaster besides those directly caused by radiation. A large number of people were evacuated form the area affected by radiation, and it's likely that harm caused by the radiation released would have been far worse if the evacuation hadn't taken place, so it makes sense to count the harm inflicted by the evacuation. There were roughly 60 people who died from disruption in medical care or from suicide resulting from the evacuation though it can be a bit difficult to tell given the disruption caused by the Tsunami.
So it was a disaster that killed roughly 180 people. Which is certainly more than one would ever want to see, but how does that compare to other forms of energy. It's almost impossible to imagine a single wind turbine killing 180 people, but you have to have many more wind turbines in operation if you're going to replace a nuclear power plant with them. If we're worried about how dangerous a source of electricity is, the best way to compare is probably to measure how many died in the generation of each Gigawatt-year of power.
Over it's lifetime Fukushima generated 877,692 Gigawatt-Hours of electricity or almost exactly 100 Gigawatt-Years. So overall it killed 1.8 people for each Gigawatt-Year of power it produced. How does that compare with other sources of electricity? Whenever I want to look up statistics on power, the first place I look is Sustainable Energy Without the Hot Air, and excellent book available free online about energy and sustainability. In chapter 24 they have an excellent table of the dangers of various ways of generating electricity. Or rather, they have number from two wide-ranging studies on the topic, which are generally produce similar numbers but look at different sets of countries over different time frames to produce their results. Sadly for us, the two studies disagreed most wildly about how dangerous coal power production is, with the EU estimate being that coal kills 2.8 people per Gigawatt-Year and Paul Scherrer Institute estimating that it only kills .4.
So in the end, we can't say whether Fukushima killed more people over the course of it's lifetime than an equivalent coal power plant, we just know that it is comparable. Of course, this isn't the same as comparing nuclear to coal. To do that you would have to include the Chernobyl explosion which killed many more people than Fukushima, but you would also have to include the hundreds of nuclear plants that complete their lifetimes without any problems. On average nuclear plants seem to result in .1 deaths per Gigawatt-Year, which is much better than forms of fossil fuel that emit a lot of particulates into the air to give people lung cancer, but roughly equivalent to wind power or natural gas.
Update: In the years this since was published the estimates of number of deaths caused by the evacuation listed on Wikipedia have gone way, way up to around 600 which puts Fukushima as a clearly worse disaster than the normal operation of a coal plant. It looks like a Fukushima disaster sans evacuation would have resulted in far fewer deaths overall but that doesn't really matter since we can probably expect similar responses in the future regardless. See here.
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