Are Nuclear Disasters Dangerous?

Joris van Dorp, MSc.
Oct 11 · 7 min read

Nuclear disasters are generally thought to be very unlikely but also very dangerous.

But just how dangerous are they?

Image of one of the damaged reactor buildings at the Fukushima Daiichi nuclear power plant.

In this post, I will draw on science to show that the radiological health consequences of nuclear disasters for the public are no more dangerous than the consequences of a more familiar risk: air pollution.


Our first stop is the United States Nuclear Regulatory Commission (NRC), known informally as the international “gold standard” of nuclear safety regulation and oversight.

It’s the toughest regulator on the planet so let’s see what it has to say about the consequences for public health of a severe nuclear disaster.

The NRC has studied accident consequences in depth in the 2007 SOARCA project, and here is a summary of what it found:

Existing resources and procedures can stop an accident, slow it down or reduce its impact before it can affect public health;

Even if accidents proceed uncontrolled, they take much longer to happen and release much less radioactive material than earlier analyses suggested; and

The analyzed accidents would cause essentially zero immediate deaths and only a very, very small increase in the risk of long-term cancer deaths.

So basically, according to the NRC, a severe nuclear disaster would do little or no harm to public health.

That’s good to know — and very different from what most people think when they hear the words “nuclear disaster” — but let’s think about this a bit more. The NRC finding of “no harm” due to a nuclear disaster assumes that people are eventually relocated away from areas that are most contaminated by radioactive fallout. But what about the environment in those areas? And what about people who cannot or do not want to relocate? What about the economic costs of relocation? Even if nuclear disasters don’t really harm people but do cause land to become uninhabitable, that’s still a very bad thing!

What we really want to know is what would be the impact of a nuclear disaster in case people in the radioactive fallout zone are not relocated, right?


Thankfully, we can draw on the findings of a recent groundbreaking quantitative study on precisely this question, undertaken by a group of universities in the United Kingdom: the NREFS project (Management of Nuclear Risk Issues: Environmental, Financial and Safety). That study was concluded in 2017 and the results summarised as follows:

The research has shown that the risk after a big nuclear accident has happened is smaller than almost everyone has realised, a result that may change fundamentally the way people think of nuclear power. The life expectancy lost through radiation exposure after even the biggest nuclear accident can be kept small, while the downside risk is limited even in the absence of countermeasures.

So that research confirms the earlier NRC findings, but it further clarifies:

Mass population movement has been shown to be a poor response to a big nuclear accident: relocation is an option that governments should use sparingly if at all.

Essentially, the study was able to determine objectively, quantitatively that relocating people out of a nuclear accident fallout zone typically does more harm than good, namely because:

The NREFS results show that the life expectancy lost through radiation exposure after a big nuclear accident can be kept small by the adoption of sensible countermeasures, while the downside risk is less severe than is widely perceived even in their absence. Nearly three quarters of the 116,000 members of the public relocated after the Chernobyl accident would have lost less than 9 months’ life expectancy per person if they had remained in place, and only 6% would have lost more than 3 years of life expectancy. Neither figure is insignificant, but both are comparable with life expectancy differences resulting from the different day-to-day risks associated with living in different parts of the UK. It is clear in hindsight that too many people were relocated after both the Chernobyl and the Fukushima Daiichi accidents. Remediation methods can often be cost-effective, but relocation of large numbers following a big nuclear accident brings its own risks to health and well-being and should be used sparingly, a message coming from all three of the quantitative methods. There is a need to understand and hence demystify the effects of big nuclear accidents so that decision makers are not pressurised into instituting draconian measures after the accident that may do more harm than good.

The NREFS study was presented in a university lecture that can be watched here:

Loss of life expectancy

To make radiation health effects comparable with other threats to health including those of air pollution, they can be quantified in terms of loss of life expectancy.

According to mainstream radiological health science as interpreted by the ICRP (International Commission on Radiological Protection), getting a radiation dose of 1000 millisievert (mSv) corresponds to a 5,5% risk of dying from cancer.

To put 1000 mSv in perspective, the radiation received by most people during their lifetime from the natural environment ranges between about 100 and 700 mSv, and according to the ICRP, it is “unlikely to be justifiable” for governments to intervene to reduce human exposure to such doses (ICRP p. 117).

Continuing, if one does get cancer due to radiation and dies from it, the average loss of life expectancy is between 8 and 22 years.

Combining the above, the loss of life due to a radiation dose of 1000 mSv of radiation is calculated to be about 9 months.

That is: a group of people exposed to 1000 mSv of radiation would be expected— on average —to live 9 month shorter than their peers who did not get exposed to that dose.

It turns out that the maximum radiation dose people could get after a worst case nuclear disaster at a contemporary nuclear plant and assuming they are not relocated, is — by coincidence — also about 1000 mSv, absorbed during a lifetime of living in the “uninhabitable” zone.

So that’s it: a nuclear disaster — at worst— will shorten life expectancy by 9 months.

That’s not cool.

We should avoid nuclear disasters.

But are they more dangerous than air pollution?

Is our fear of being caught in a nuclear disaster fallout zone justified?

Air pollution

Outdoor air pollution kills about 4.200.000 people every year, a number equal to half the population of New York City, USA.

9 out of 10 people globally breath polluted air and the World Health Organisation warns it is literally destroying our health.

93% percent of the worlds children are breathing polluted air, which is killing 600.000 of them every year.

This is happening all over the world, in all towns and cities, not just in the developing world.

On average, humanity at large loses 1,8 years of life expectancy due to air pollution. That’s twice as much as people living in the middle of a nuclear accident fallout zone would lose if they were so bold as to refuse being relocated!

Let’s compare the stark statistics on air pollution with the conclusion of the NRC, already noted above …

The analyzed [severe nuclear] accidents would cause essentially zero immediate deaths and only a very, very small increase in the risk of long-term cancer deaths.

… and with the consequences of the Fukushima nuclear disaster, reported by the World Health Organisation.

From a global health perspective, the health risks directly related to radiation exposure are low in Japan and extremely low in neighbouring countries and the rest of the world.

Showdown: Radioactive fallout from nuclear accidents versus air pollution

The effects of conventional air pollution and radioactive pollution due to the Chernobyl and Fukushima nuclear accidents can be visualised together on a map of the globe.

Comparing loss of life expectancy due to nuclear accidents and due to air pollution. Graphic created by combining information from the Air Quality Life Index.


Feeling safe and being safe can be very different things and nowhere is that more evident than with nuclear energy and radiation.

However, we need to learn to redirect our fears because we simply cannot afford to solve our global climate and energy challenges without using more nuclear energy, and nuclear energy can only be deployed efficiently in societies that are aware of its remarkable safety even in the case of a severe accident.

I’ve not gone into how modern plants are much safer than legacy plants, or that upcoming “Generation IV” plants are safer still, but I hope you have seen that potential nuclear disasters even at today’s operating plants are not just highly unlikely but also objectively safe compared with the far greater present risk of air pollution.

Thank you for reading this far, and please spread the word!

Not being opposed anymore to nuclear energy is great, but it’s not enough. We must stand up for nuclear and urge our compatriots and the traditional environmental groups to embrace the holistic use of civilian nuclear energy technologies. Please ask your environmental charity to (re)consider nuclear energy, or find a pronuclear advocate or advocacy group you like and support them!

Generation Atomic

Energizing and empowering today’s generations to advocate for a nuclear future.

Joris van Dorp, MSc.

Written by

I am a master of engineering working in the field of energy efficient and environmentally friendly building construction, focusing on indoor climate and HVAC.

Generation Atomic

Energizing and empowering today’s generations to advocate for a nuclear future.

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