What does research say about the safety of nuclear power?

I’ve been answering almost exactly the same answer to multiple discussions where people make claims about the safety of nuclear power, so I think it’s time to create a single post with collected information, links, and explanations. This is intended to be a living document, so please, if you have any suggestions about things to add or to remove, leave a comment!

As of 2017, the general results are clear: even and particularly when the entire lifecycle (uranium mining, accidents and nuclear waste included) is considered, nuclear energy is one of the safest energy sources ever employed by humans. There is no doubt whatsoever that even if we totally discount the risks of climate change, energy produced from nuclear power is responsible for very, very much less harm to people and the environment than similar amount of energy generated by any method that relies on burning something. This result is supported not only by mainstream science but also by research commissioned in 2013 by Friends of the Earth UK, and even Greenpeace tacitly agrees. Actual scientists are far more certain. 

In the following, I’m ultimately going to break this argument into four sections: 1) overall studies, 2) mining, 3) normal operation and accidents, and 4) waste. As of now, sections 2 and 3 in particular are in dire need for more information.

1. Overall studies

ExternE (2005): Probably the most thorough study on the lifecycle risks of energy generation is the EU-funded ExternE (External Costs of Energy) study. Running from the early 1990s to 2005, it meticulously assessed the so-called “externalities” – the damages and costs that were not included in the price – of different energy sources in Europe. Its assessment of nuclear energy’s risks included nuclear accidents so far, and a scenario about a very serious accident in densely inhabited Central France leading to people dying of acute radiation sickness outside the plant (that is, a far more serious radiation release than what happened at Fukushima, for example). If anything, it was conservative in its assumptions about the dangers of nuclear energy. Nevertheless, as reported by e.g. Markandya and Wilkinson (2007) in The Lancet, one of the leading medical journals in the world, it concluded that nuclear was clearly one of the safest energy sources ever.

markandya and wilkinson 2007 table 2 health effects of electricity generation

Table 2 from Markandya and Wilkinson (2007), showing the results of the ExternE study.

It should be noted that the ExternE study could not reliably assess the health impacts of solar and wind energy, as these energy sources didn’t have a long enough history needed for assessing their long-term effects. However, there is every reason to believe that the lifecycle impacts of solar and wind energy are about as small as those of nuclear power.

Friends of the Earth (2013): In 2013, environmental organization Friends of the Earth UK commissioned an independent research review of scientific research relevant to Britain’s proposed new nuclear power project. The review was conducted by the respected Tyndall Centre of the University of Manchester, and is worth reading in full. Regarding the lifecycle risks of nuclear energy, the report concluded (p. 16; the full report can be found here – PDF link):

“Overall the safety risks associated with nuclear power appear to be more in line with lifecycle impacts from renewable energy technologies, and significantly lower than for coal and natural gas per MWh of supplied energy.”

Ecofys study for the European Commission (2014): This study, conducted by a consulting agency regularly used by environmental organizations, evaluated the total subsidies and the monetary value of environmental (including health) impacts of different energy sources within the EU. The results are shown below. (Note that the original study included resource depletion as a cost; the figure below leaves that out as it’s not a health and safety hazard. Some of the costs attributed to “Climate change” and “Other” should also be discounted on the same basis, but the data is not presented in enough detail to do so.)

Ecofys 2014 study health impacts only.001

External costs of EU energy sources according to Ecofys (2014), Subsidies and Costs of EU Energy. Data from Figure 3-8 and Annex 1-3, Table A3-8. Resource depletion not shown.

Okala design guide and EcoInvent database (2014): A valuable “simplified” lifecycle assessment tool developed specifically for designers, the Okala design guide (White et al. 2014) originally published by the Industrial Designers’ Society of America, gives designers the toolkit required to roughly assess the lifecycle impacts of their designs. Among hundreds of materials and processes, the guide also includes assessments for the environmental “footprint” of various electricity sources. The figures in the following table give the overall environmental impact in “Impact Factor Points”. The number includes weighed environmental and health impacts, but does not include possible long-term impacts of radioactive waste (which, as we shall see below, may however not be as large as many believe). The source for all these numbers is the EcoInvent database maintained by the Swiss Federal Institute of Technology.

Okala 2014 electricity

Impact factors, i.e. magnitude of environmental and health impact, for various electricity sources. White et al. (2014), p. 47.

(As a former partner in an eco-design company Seos Design, Okala guide’s 2007 edition was actually one of my first brushes with the uncomfortable truth: that environmental organizations haven’t been telling the whole story about nuclear energy.) 


Anderson, K. et al. (2013). A Review of Research Relevant to New Build Nuclear Power Plants in the UK (commissioned by the Friends of the Earth UK). Tyndall Centre, University of Manchester. https://www.foe.co.uk/sites/default/files/downloads/tyndall_evidence.pdf Accessed 10.3.2017.

Ecofys (2014). Subsidies and costs of EU energy (incl. Annexes). http://ec.europa.eu/energy/en/content/final-report-ecofys Accessed 10.3.2017.

Markandya, A., & Wilkinson, P. (2007). Electricity generation and health. The Lancet, 370(9591), 979-990. https://doi.org/10.1016/S0140-6736(07)61253-7

White, P., St. Pierre, L., and Belletire, S. (2014). Okala Practitioner. Integrating Ecological Design. Okala Team / IDSA, Phoenix.

2. Mining

Despite every effort and numerous requests for information to anti-nuclear activists and organizations, I haven’t been able to find detailed studies comparing the safety hazards of uranium mining to the safety hazards of other mining activities. As such, this section is very much a work in progress. If you can help me out, I’d be very grateful.

However, what information I’ve been able to find suggests that the risks and dangers of uranium mining are likely to be no larger than the risks and dangers of mining similar minerals – including rare earth metals much in demand in renewables industry. My own lifecycle assessments, made using data from a study published in Nature Geoscience (Vidal et al. 2013a, b), information supplied by wind power manufacturer Vestas, and my own calculations about mining requirements (as a someone whose PhD is mostly about copper mining I feel qualified to make rough assessments) suggest that overall, mining requirements (that is, materials moved, or the “material backpack”) per kilowatt hour of electricity generated are about the same with renewables and with nuclear power. It is also instructive to note that uranium mining is fairly small part of the overall mining requirement.

As such, as long as uranium mining is not very much more damaging to health and environment as other similar mining operations operating on the same scales (and I’m unable to find any data to support such an assumption), it seems most likely that the overall hazards of mining are comparable between renewables and nuclear. We know for a fact that materials required for renewables cause health and environmental damages as well, and it’s reasonable to assume that overall health and environmental effects are roughly proportional to the overall quantity of materials (“material backpack”) required. Click here for the full post where I discuss these issues; below is the overall assessment. Note that uranium mining is assumed to use the very poorest of ores currently used, and that both in-situ leaching (with very much smaller environmental footprint) and uranium extraction as a byproduct (which causes only a marginal footprint as well) are ignored entirely.

Mining requirements for selected raw materials

Calculated after Vidal & Arndt (2013b) and various sources for mining requirements. Uranium mining is assumed to take place at the poorest primarily uranium-producing mines (ore grade 0,1%); other materials are computed using average ore grades and average global recycling levels (30% for steel, 10% for concrete, 22% for aluminum, 35% for copper).


Vidal, O., Goffé, B., & Arndt, N. (2013a). Metals for a low-carbon society. Nature Geoscience, 6(11), 894–896. https://doi.org/10.1038/ngeo1993

Vidal, O., & Arndt, N. (2013b). Metals for a low-carbon society: Supplementary Information. Nature Geoscience, 6(11), 15–17. https://doi.org/10.1038/NGEO1993

3. Operation and accidents

Greenpeace (2006-2013): For reasons that may by now be obvious, Greenpeace does everything it can to avoid comparing the safety statistics of nuclear power to any of its alternatives. However, the organization’s own research is instructive to compare nevertheless. According to Greenpeace’s 2006 report on the effects of Chernobyl disaster (PDF link), this largest nuclear disaster ever will ultimately result to 192 000 excess deaths (even though reaching that figure will require, among other things, that all increases in mortality from cirrhosis of the liver after 1986 in the areas even slightly affected by the fallout is assumed to be due to Chernobyl). At the same time, a 2013 assessment of the health risks of coal commissioned by Greenpeace (Myllyvirta 2013), but conducted in a somewhat more reliable manner by Stuttgart University, concludes that the 300 largest coal plants in Europe are alone responsible for some 22 000 excess deaths per year. The figure does not include risks of CO2 pollution. If we therefore believe Greenpeace’s own reports, if the price of the closure of only the 300 largest coal power plants in Europe was a Chernobyl-scale disaster every ten years, that would be an improvement in public health.

The TORCH report and the European Greens (2006): “The Other Report on Chernobyl” (TORCH; Fairlie and Sumner. 2006), commissioned by the European Greens (the organization of the Green parties in the European Parliament) as a counter to WHO studies that find at most 4000 excess deaths due to Chernobyl, suggests that Chernobyl may cause 30 000 to 60 000 excess deaths in total. These figures were reached by calculating the risks of low radiation doses in a way that the independent International Committee for Radiation Protection – the foremost scientific authority in radiation safety – expressly advises shouldn’t be used. If we believe the European Greens over Greenpeace on Chernobyl, a Chernobyl every three years would be preferable to the 300 largest coal plants. Even if we totally discount the risks of climate change.


Fairlie, I. and Sumner, D. (2006). The Other Report on Chernobyl (TORCH). http://www.chernobylreport.org/?p=summary Accessed 10.3.2017.

Myllyvirta, L. (2013) The Silent Killers: Why Europe must replace coal power with green energy. Greenpeace.http://www.greenpeace.org/international/en/publications/Campaign-reports/Climate-Reports/Silent-Killers/ Accessed 10.3.2017.

4. Waste

Onkalo nuclear waste repository, Finland: The dangers of nuclear waste have been studied very thoroughly in a flood of reports and assessments evaluated by the Finnish Radiation Safety Authority (STUK) during the preparation of the Onkalo nuclear waste repository – the first of its kind to receive the construction permit and most likely the first to become operational in the world in 2020s. I’ve gone through some of the material, hunting for the worst-case scenarios. This is what I’ve found:


This is the worst-case scenario from the externally reviewed Posiva 2009 Biosphere Assessment Report (Hjerpe et al. 2010, p.137 in particular). It requires

  1. Someone to spends all of his or her days – from birth to death – in the single worst contaminated one square meter plot around the repository, while:
  2. Eating nothing but the most contaminated food available, with a diet that maximizes radionuclide intake; and
  3. Drinking only the most contaminated water and nothing else.

The resulting maximum exposure – 0.00018 milli-sieverts per year, much less if any one of the above requirements aren’t met – also requires that the copper canisters which house the spent fuel effectively vanish after mere 1000 years, while the bentonite clay barrier that alone is a very effective catcher of radioactive particles must also disappear somewhere, and the groundwater must move towards the surface. (BTW, read this interview of an actual radiochemist about the effectiveness of bentonite.) Note that even if the canisters begin to leak immediately, the maximum exposure occurs only after some 10 000 years (AD 12 000) as it will take time for the radioactive materials to migrate to the surface. After AD 12 000, doses will fall steadily.

I’m all for being critical towards assessments made by a company responsible for building the Onkalo, but it seems that safety margins are nevertheless considerable. STUK agreed, and gave Posiva a permit to proceed with construction in 2015. It’s worth noting that no anti-nuclear organization or activist has been able or willing to provide any assessment that shows significantly higher exposures or otherwise invalidates the Posiva scenarios. (Because the above scenario already accounts for the three most common anti-nuclear arguments: that copper canisters might not last 100 000 years, that bentonite clay may erode, and that groundwater movement toward the surface may be faster than expected.)


Hjerpe, T., Ikonen, A. T. K., and Broed, R. (2010) Posiva Biosphere Assessment Report. Posiva 2010-03. http://www.posiva.fi/files/1230/POSIVA_2010-03web.pdf Accessed 10.3.2017.

About J. M. Korhonen

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This entry was posted in Ecomodernism, Energy, Nuclear energy & weapons, What they aren't telling you about nuclear power and tagged , , , . Bookmark the permalink.

23 Responses to What does research say about the safety of nuclear power?

  1. Good summary, thank you. On the materials input: Is the steel & concrete input for nuclear so small that it cannot be seen? Also note that the recycling rate for the steel that has seen neutrons (RPV and internals) may be zero, though I think the French have some plans to re-use activated steel for new reactor components.

    For the Finnish repository route we also have to take the copper canisters into account.
    In a rough estimate, each will contain 12 PWR fuel elements with about 0.5 t HM each. Assuming a burnup of 35 GWd/tHM and 33% thermal efficiency we get 1.66 TWh per canister.

    The canisters have 1m diameter and are 4m tall and have a surface area of 14 m^2 so the 5cm copper wall will contain about 6t of copper (maybe you have better figures here).

    So we get an estimate of 4g copper per MWh which will never be recycled. Average copper ore grades are about 0.2% now, so the mining effort is 2kg/MWh and would be just about visible on your graph.

    Cost wise, copper currently is €5.3/kg, so the copper canisters add just €0.02/MWh or a negligible 0.002cent per kWh.

    Personally, I think that 5cm wall thickness is a ridculous over-engineering, given how tiny the consequences of early leakage are. If you offer the antis 5cm copper, they will demand 5cm gold. They will never admit that it is safe.

    • Yes, steel and concrete inputs for nuclear are included but they aren’t visible in the graph.

      Good point about copper, though – I think your estimate is within the ballpark but have to check this some day.

      Many knowledgeable people in Finland doubt whether we’ll ultimately proceed with Onkalo as it is, as the fuel is still quite valuable. Might be that we’ll use it as an interim storage of sorts while waiting for fast reactor and/or MSR technology to mature. Afterwards, well, there’s still a need for a 300-year repository, and there’s always mushroom farming…

      • Using it for fission product waste after moving to fast reactors would of course make a lot of sense. Vitrified fission product waste in bentonite in a deep repository is safe without copper canisters.
        Due to the long-lived fission products a geological repository is still useful. Yes, per kWh the mercury released by coal plants is about 200 times more toxic than the I-129 produced by fission, but that does not mean that the latter should be released into the environment, as better alternatives exist.

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  3. Thank you for the page. I too have grown weary of trying to explain the simple facts to naive and ignorant Greens that appear convinced that only they can be correct based on misinformation that they have read in the Green echo chamber.

  4. Show me one company or even one government that has existed longer than U235 half-life? There are none, so no matter how hard you try to convince us that companies and governments will be around long enough to keep it safe, you can not support it with evidence…

    • You seem to have confused long half-lives with danger to the environment. This is a common mistake, but it is nevertheless a mistake.

      Consider steel, for example. The primary elemental component of steel, iron, has for all intents and purposes an infinite half-life. Its half-life is therefore very much longer than that of uranium. But people do not consider it dangerous. Why?

      Because the longer the half-life, the less radioactivity is emitted.

      Uranium is definitely bad for health if it is ingested. But the main cause for danger is its chemical toxicity – it’s a heavy metal, like lead, or cadmium, which incidentally is used in certain solar panels. While it’s good that such chemicals are isolated from the biosphere, it should be noted that nuclear industry is the only energy industry that is totally obligated to take care of practically all of its waste. No alternative has anything remotely similar obligations.

      And, if you are concerned about Uranium 235, you might find some comfort from the fact that that is precisely the isotope that is destroyed in nuclear reactors. While traces of it remain in used fuel, used fuel generally contains less U235 than natural uranium.

      Which, by the way, exists in such an abundance that the bedrock above the Onkalo, the Finnish nuclear waste disposal site mentioned in the text, contains far more uranium than what will be entombed within Onkalo’s caves.

      May I also suggest you to search for Oklo natural nuclear reactors? There, at least 16 separate “natural reactors” existed in an uranium orebody about two billion years ago. The reactors worked for about 250 000 years, that is, two times longer than humans have been around, and they were in a groundwater reservoir (that was actually what made them work). Despite having come into being by accident, the waste from these reactors – which is identical to the waste human-built reactors generate – travelled no more than few tens of meters from the orebody, and almost certainly caused very little or no harm to the environment.

  5. Philip White says:

    As one of the authors of Okala Practitioner that you mention, I verify that the Okala Impact values for boiling water and pressure water fission reactors are based on the ecoinvent inventory data supplied by the Swiss Federal Institute of Technology. The life cycle assessment characterization method that was applied to make the Okala Impact factors was TRACI, developed by the US EPA. The method does not include the impact category of ionizing radiation, as do some LCA characterization methods. In my experience working with other LCA characterization methods that model ionizing radiation, the supportive inventory data also does not include emissions from stored nuclear waste, and the relative scale of ionizing radiation impacts compared to other impact categories is relatively low. I am surprised that you did not also publish the CO2 equivalent values per kW-hr which were also in the original table from Okala Practitioner. These values also show nuclear fission electricity in a relatively positive light. Your statement ‘The number includes weighed environmental and health impacts, but does not include possible long-term impacts of radioactive waste (which, as we shall see below, may however not be as large as many believe)’ is problematic, because you make a postulation (that the impacts of nuclear waste storage are low), as if it were a fact. In my opinion, if you offered a less ‘pro-nuclear’ position, it would increase the objectivity and value of your message.
    sincerely, Philip white (www.okala.net)

    • Thank you for your comments, and many thanks for the good work in the Okala guide – although it did lead me down to a rabbit hole I sometimes wish I hadn’t explored.

      I try to be pro-facts, not pro-nuclear; however, I do understand from personal experience that after being exposed to the one-sided view that mainstream environmental organizations tend to present about nuclear energy, accepting that pro-facts position supports many pro-nuclear arguments can be difficult. The reflexive anti-nuclear attitude adopted by many in the environmental sector is very hard to shake off; again, I speak from personal experience as a someone who once deemed nuclear energy as an unnecessary risk at best. What happened to me and to many others was a classic cognitive bias, ably used in service of anti-nuclear arguments: when presented with two competing claims, one very low and one very high, we tend to assume that the truth can be found from somewhere around the middle. This, however, is a logical fallacy.

      After studying the energy sector for a decade now, I’ve concluded the weight of evidence suggests that risks of nuclear waste are very unlikely to be nearly as large as many people seem to believe. After all, I at least have heard repeatedly that nuclear waste presents a totally unsolvable and extremely hazardous problem. Many are even claiming that it is the worst environmental problem in the world, which is patently absurd.

      The risks are not nonexistent, and nuclear waste could well cause serious but ultimately local environmental and health problems. Nevertheless, compared to other energy sources and their waste and other issues, the risks are by any measure limited, and I believe my original statement – where I was careful to use the word “may” – was justified by the facts as we know them at this point. If the facts change, I will of course change my opinion.

      It is true that we don’t really know how nuclear waste will behave in the millennia it needs to be sequestered (provided that it isn’t re-used earlier, which seems to be a distinct possibility). However, we do know from so-called natural analogies such as Oklo that radionuclides are unlikely to migrate in quantities that would present a clear environmental or health hazard, even when the barriers are accidental and natural, not specifically engineered. I suspect this is understood at some level by anti-nuclear campaigners as well; otherwise it is difficult to understand why they steadfastly refuse to actually quantify their estimates of the dangers of nuclear waste, preferring instead weasel words such as “danger” or “leaks”. That leaks can happen is not in doubt; how large their impacts could be is the key question.

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