Nuclear Accidents

Fear is the Largest Health Hazard of Nuclear Accidents

The mere possibility of nuclear accidents is one of the biggest worries people have when it comes to nuclear power. Even if the accidents are quite rare and unlikely, they can cause significant harm and damages. But how significant, and what kind of damages?

The history of civilian nuclear power knows of three major accidents. In 1979, reactor number 3 at Three Mile Island suffered a partial core meltdown. A few years later in 1986, reactor number 3 (what is it with these #3 reactors?) at Chernobyl had the worst nuclear power plant accident in human history. And in 2011 a tsunami, started by a massive earthquake, washed over the reactors at Fukushima Daiichi on the Japanese coast, causing three of them to suffer a core meltdown during the following days. A core meltdown is the worst that can happen to a nuclear reactor, as it almost certainly wrecks the reactor beyond repair and can cause radioactive substances to be released to the environment.

So, nuclear accidents do happen. And they have been happening more frequently than we predicted. In my previous article[linkki], I concluded that according to major studies, nuclear power remains, even with the accidents, waste [linkki] and all, our safest way to produce energy. How can both be true? To find out, we need to ask what are the actual consequences of these accidents.

Third place: Three Mile Island

The third worst civilian nuclear accident is the partial core meltdown at Three Mile Island power station back in 1979. Nobody died as a direct result. The accident was caused by several different things conspiring together at the same moment. The most critical ones were certain valves that had been closed due to maintenance (against instructions) and the mechanical fault of one pressure release valve that got stuck in “open” position, allowing the coolant fluid to leak from the system[i]. Operator skills were also found to be somewhat lacking.

Even if nobody actually died, the clean-up costs were high, around two billion dollars. Officials proved to have terrible communications on the matter, which led to fear, unnecessary evacuations and growing distrust. The accident, along with the fear and loathing that grew with it, fed the national and global anti-nuclear movement. This, in part, led to may cancellations of nuclear power plants being planned or even already being constructed. Instead of nuclear, the world embraced coal, which very likely ended up causing much more environmental and human harm.

Second place: Fukushima nuclear accident

The second place in our history of worst nuclear accidents goes to Fukushima Daiichi[ii]. Economic damages were immense, but even with three reactors having a meltdown, no serious health hazards were caused due to radiation releases. During the next half century, the health effects will be so small as to remains statistically impossible to detect[iii]. This is in part due to informing citizens and giving them preventive measures (such as iodine-pills) as well as relatively benign winds that helped push most of the radioactivity to the Pacific Ocean.

As a direct result, the Japanese nuclear power sector was almost completely shut down. Even with heroic energy conservation efforts, it was replaced mainly with fossil fuels. The health effects due to this burning will cause more harm to the environment and human health in one year than the radiation released due to the accident will cause ever.

The evacuation, along with the radiation fear and social stigma of the victims has caused and will keep causing significant human harm. Fear, anxiety and other psychological harm will in turn increase risk behaviour and can lead to abuse of drugs and alcohol. One of the most important lessons learned from Fukushima for society, media and anti-nuclear activists is that the biggest harms will be caused by the often unnecessary fear they help spread, not the accident itself.

First place: Chernobyl nuclear accident

The worst nuclear accident in our history happened in Chernobyl in 1986. For many, the first question that pop to mind is “Can this happen to our reactors, in Finland or other western country?” In practice, no, it can’t. The reactor used in Chernobyl, called RBMK, is a strange design only built in the Soviet Union[iv]. One of the strangest things in it is that when the coolant (water) is removed, the nuclear reaction actually accelerates. The designs such as Pressurized Water Reactor (PWR) or Boiling Water Reactor (BWR) now in use in western countries act the opposite: if you remove the coolant, the chain reaction stops, as the coolant water is also the moderator that makes the reaction possible in the first place.

And that “positive void coefficiency” was not the only strange thing about the RBMK that made it more susceptible to accidents. The control rods also had an unsafe design. It was physically enormous, so to save costs, no containment building was built around it. This omission made sure that if something did happen, it would have much larger impacts. In normal use, and when used according to the proper operation manual, even the RBMK was safe to use (and has been, as there still are some eleven reactors running, although they have undergone safety modifications). But the operation manual was lacking, it had not been read carefully enough, and on the faithful day of the accident, the reactor was operated anything but normally.

Due to many unfortunate coincidences, bad safety culture, problematic reactor design and the secrecy of Soviet officials, a safety test made on reactor 3 resulted in it having a total, spectacular meltdown, spewing much of the radioactive material in its core to the skies, where it spread all over Europe. The Soviet era secrecy, which especially considered all things nuclear, meant that the people living nearby did not receive any instructions to not eat or drink local produce nor did they receive iodine-pills from the officials in the coming days. These measures, should they have been taken, would have negated much of the health risks from the radiation. There were also deaths during the heroic firefighting that tried to put out the burning graphite in the reactor core. All in all, around 50 deaths have been directly linked as caused by the accident (WHO 2005[v]).

Modeled Fatalities and Environmental Damages

The stochastic (statistical) effects of radiation in large populations are estimated using different models. A commonly used Linear No-Threshold model (LNT) estimates that around 4,000 people of those who received a more significant radiation dose will die prematurely because of it. In addition, LNT-model predicts that much smaller doses (doses that people routinely receive from medical procedures such as CT or PET scans) are estimated to cause some 5,000 premature deaths among the roughly 5 million people who received them. One should remember that these are uncertain results, as the LNT model is rather unreliable with very small doses. Our bodies are much more capable in repairing small radiation damages (which it does constantly due to background radiation) than damage from massive doses. Yet this is something that the LNT as such ignores.

The evacuation zone around Chernobyl is not a radiation wasteland – perhaps contrary to popular belief. The effects of the extra radiation to the local ecosystems has been small. In fact, since humans left largely due to their fear of radiation, the area has been reclaimed by “wild nature” again, which is thriving.

Fear is the largest danger from nuclear accidents

Nuclear accidents are a serious matter. But against common belief, radiation is not among the biggest dangers and risks nuclear accidents present. Much more harm is done due to for example the breaking up of communities, fear and anxiety taking control of people’s lives, society stigmatizing the “victims” and the risks to one’s mental health and further risky behavior and drug abuse that all of the above causes. These health hazards have a lot to do with our society’s rather hysteric relation to radiation in general. For comparison’s sake, coal burning in Europe alone causes more than 20,000 premature deaths every year, without any actual accident happening. Perhaps that is why there is preciously little headlines telling us about those victims.


[i] There is a wealth of literature explaining step by step what actually happened during these accidents. One comprehensive book is Atomic Accidents: A History of Nuclear Meltdowns and Disasters: From the Ozark Mountains to Fukushima by James Mahaffey (2015).

[ii] Some say that Fukushima is the worst one, since three reactors had a core meltdown, but from the point of harm done to humans, it was second worst.


[iv] More info can be read at


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