• Raphaël Champeimont

Nuclear power is not as dangerous as you think

Updated: Nov 27, 2020

Nuclear power is probably the most controversial energy source. Its advocates see it as a cheap energy source that is necessary to prevent global warming. Its radical opponents think it is so dangerous that they would even prefer to face global warming instead. The scale of accidents and the strange nature of radioactivity make it especially terrifying, but when taking a rational approach, is it really that dangerous?

Let’s explore what people usually think about nuclear power and how it compares to reality.

See also: French version 🇫🇷

No conflict of interest: The author of this article and this blog do not receive any money from, nor have any financial interests in the nuclear industry.

#1 Nuclear plants release radioactivity in the environment

Reality: It’s technically true, but even if you live near a nuclear power plant, the extra radiation you receive is much lower than natural radioactivity.

You may not know about it, but you live in radioactivity. Your food is radioactive. Your house is radioactive. You and other humans are radioactive. However, this is not dangerous, because the amount of radiation you receive is very small. This is called natural radioactivity and has always been there long before the development of nuclear power. It is called natural radioactivity because it is naturally present, but it is the same physical phenomenon as radioactivity from artificial origin. This natural radioactivity exposes you to a small level of radiation all the time. Moreover, you also receive some radiations directly from the Sun (which is a gigantic nuclear fusion machine).

Natural radiation near Paris: 0.1 µSv/h

You can measure radiation using a Geiger counter. Anyone can buy one (price is between $100 and $ 200). I own one and I have measured the level of radiation at my home (see photo) which is 0.1 µSv/h. It means my body receives 0.1 µSv of radiation every hour. A “µSv” is a microsievert, that is a millionth of a Sievert, a radiation unit.

If you live in the mountains, you are exposed to more radiation, because you are less protected by the atmosphere from the Sun radiation. I made a measurement at an altitude of 3,000 m (10,000 feet) in the Alps and found a radiation level about twice as high (0.2 µSv/h). So the natural level of radiation varies with altitude, and in fact it varies even at a similar altitude, because the rocks in the ground are more radioactive in some parts of the world than others.

Now let’s talk about nuclear power plants. They do emit some radiations, but the extra radiation received near one is much lower than the natural level of radiation. If you drove near a nuclear power plant while holding at a Geiger counter, you would probably not even see any change in the value displayed.

In practice, people living near a nuclear power plant are exposed to a few extra microsieverts (µSv) per year, while natural radiation already exposes them to a few microsieverts per day.

You might ask, what is a dangerous radiation dose then? The lowest level of radiation for which a cancer increase risk has been observed is around 100 mSv (= 100,000 µSv) which increases the cancer risk by at worst 0.5% (with the most pessimistic model). If someone receives more than 400 mSv (= 400,000 µSv) in a short period of time (ie. during a nuclear accident for example), symptoms of radiation poisoning can appear. The lethal dose is around 4 Sv (= 4,000,000 µSv). If you want to see more examples of order of magnitude for radiation, you can look at this excellent chart.

#2 Accidents have worldwide effects on health

Reality: Unless you lived in Ukraine or Belarus when the Chernobyl accident occurred, the radiation doses you have received from nuclear accidents are comparable to natural radioactivity.

In the days that followed the Fukushima nuclear accident, I had the idea to use my Geiger counter to measure radiation when the radioactive cloud passed over France. However, I wasn’t able to see any difference at all compared to the normal level of natural radiation (0.1 µSv/h). With such low levels of radiation, the impact on health in Europe of the Fukushima accident is negligible.

However, we might legitimately ask the same question for the Chernobyl disaster. The Chernobyl accident released about 10x more radioactive material than the Fukushima one, and Ukraine (USSR in 1989) is of course much nearer to Western Europe than Japan. So what was the impact on people’s health in Western Europe at the time of this accident? According to the UNSCEAR (the United Nations organization in charge of radiation), the radiation received by Western Europeans is lower than the natural radiation level over the first year after the accident, that is when radiation was the highest. To be precise, it was less than 1 mSv/year, while average natural radiation is 2.4 mSv/year. This might come as a surprise for people living in Western Europe who are convinced that their government lied to them to minimize the risks. But yes, the doses received by Western Europeans for the worst nuclear accident in history are really that low.

Of course, there is no denying that people living near the Chernobyl plant were hit by dangerous nuclear radiations. They received significant doses, high enough to increase the risk of thyroid cancers (around 6,000 cases occurred).

#3 Nuclear power is the most dangerous energy source

Reality: Depending on estimates, between 4,500 and 20,000 people have died because of nuclear energy. But compared to other sources of energy, nuclear power kills relatively few people for the energy produced.

Nuclear accidents are like airplane crashes: they are spectacular and make the news. But car crashes kill a lot more people. It is the same for nuclear power, with fossil fuels being the equivalent of cars. The WHO estimates that more than 4 million people die every year because of outside air pollution, mostly caused by the use of fossil fuels. When compared to the amount of electricity produced, nuclear power is just a little more dangerous than renewables, but far less dangerous than fossil fuels (see chart below).

We could stop here, but I fear you would find these numbers unconvincing without more explanations. So let’s talk about nuclear accidents a little more to understand how we reach these counts.

Nuclear accidents

The oldest major nuclear accident in a power plant happened in Three Mile Island in the United States in 1979. But it released little radioactive material in the environment and had no effect on people's health. To give you an order of magnitude, it released about 10x less radioactivity than the Fukushima accident, which itself released about 10x less radioactivity than the Chernobyl accident.

So let’s talk about Chernobyl, the worst nuclear accident in history, which happened in Ukraine (USSR) in 1989. When considering radiation impact on health, there are two kinds of effects. First there are short-term effects, for people who receive very high doses of radiation in a short time. This is called Acute Radiation Syndrome and the symptoms are directly visible. Around 30 people died this way. But the evacuation was not carried immediately, and a large part of the population was also exposed to radiation. For them, the effect is an increased probability of developing a cancer, which can occur more than a decade after the exposition. According to the WHO, an estimated total of 4,000 people will die or have already died because of extra cancers caused by radiation exposure. Some models estimate higher counts, from 9,000 to 16,000, by extrapolating effects to populations in which the effect on cancer occurence is so small that it is impossible to verify. In the chart shown above, the 4,000 dead estimation is used. If we multiplied the death rate by 4 to use the 16,000 estimation, it would give a value of 0.28 which would not change the main point here: nuclear power is much less dangerous than fossil fuels.

Finally, let’s talk about Fukushima (2011). This accident is different from others because it was the consequence of a natural disaster. The earthquake and tsunami themselves killed 16,000 people. Because of the tsunami, electrical lines linking the plant with the electrical grid were destroyed as well as the backup pumps that would be used to cool the nuclear reactor. The result was a failure to cool the reactor, leading to the release of radioactive material in the environment. Thanks to evacuation, only 2 people received high doses of radiation. However, 573 died because of the evacuation itself (because of stress or because they were people needing special care). Some other sources give a more pessimistic estimate around 2,000. This sounds counterintuitive because we might think that the more people we evacuate, the safer it is. Even though these people did not die of radiation, we should still count them as deaths caused by nuclear power to get an honest view of risks associated with each source of energy.

Alternative estimation

I would also like to propose my own estimation. To get an idea of the deaths we can expect in the future by using nuclear power, I think it is too pessimistic to take into account Chernobyl, because the plant had clear design flaws which the current plants don’t have any more. Even in 1989, such an accident was already impossible in the West, because plants there had a containment structure to reduce the public exposure in case of an accident. On the other hand, I think the Fukushima accident can give a good idea of what a present-day nuclear accident can look like. So let’s assume that there is a Fukushima-like accident every 20 years (Chernobyl and Fukushima accidents are separated by 22 years) at the current rate of production. In the last 20 years, the world nuclear plants have produced around 50,000 TWh of electricity (2000-2019). Let’s take a more pessimistic estimate for the number of deaths in Fukushima and assume that 2,000 people died instead of 573 like in the chart.

We can then compute the death rate in the same unit as the above chart:

2,000 deaths / 50,000 TWh = 0.04 deaths/TWh

This gives an even better result for nuclear power than in the chart (0.07 deaths/TWh), which by this new estimate is as safe as wind power! This means that even if we don’t improve nuclear power plant safety at all – and we should – nuclear energy is as safe as renewables. And of course, work is ongoing to improve plant safety, so we can expect this rate to be even lower in the future.


Nuclear energy has a bad image as a dangerous energy source. But when looking at the actual numbers, it kills very few people. I think that understanding this counter-intuitive fact is a first step at taking a rational view of the different energy options, to make enlightened choices about the future.

Here I have not talked about many other criticisms made against nuclear energy (nuclear waste management, limited resources, cost, nuclear proliferation risks), and I plan to talk about these other issues in other articles.

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