Nuclear generation does not directly produce sulfur dioxide, nitrogen oxides, mercury or other pollutants associated with the combustion of fossil fuels. Nuclear power has also very high
surface power density, which means much less space is used to produce the same amount of energy (thousands times less when compared to wind or solar power). The primary environmental effects of nuclear power come from
uranium mining, radioactive effluent emissions, and
waste heat. Nuclear industry, including all past nuclear weapon testing and nuclear accidents, contributes less than 1% of the overall
background radiation globally. A 2014 multi-criterion analysis of impact factors critical for biodiversity, economic and
environmental sustainability indicated that nuclear and wind power have the best benefit-to-cost ratios and called environmental movements to reconsider their position on nuclear power and evidence-based policy making. In 2013 an open-letter with the same message was signed by climate scientists
Ken Caldeira,
Kerry Emanuel,
James Hansen,
Tom Wigley and then co-signed by many others. Resources usage in uranium mining is 840 m3 of water (up to 90% of the water is recycled) and 30 tonnes of per tonne of uranium mined.
Energy return on investment (EROEI) for a
PWR nuclear power plant ranges from 75 to 100 meaning total energy invested in the power plant is returned in 2 months. Median
life-cycle greenhouse-gas emissions of nuclear power plant are 12 gCO2eq/kWh. Both indicators are one of the most competitive of all available energy sources. The
Intergovernmental Panel on Climate Change (IPCC) recognizes nuclear as one of the lowest lifecycle emissions energy sources available, lower than solar, and only bested by wind. The US National Renewable Energy Lab (NREL) also cites nuclear as a very low lifecycle emissions source. In terms of life-cycle
surface power density (land surface area used per power output), nuclear power has median density of 240 W/m2, which is 34 times more than solar power (6.63 W/m2) and 130 times more than wind power (1.84 W/m2) meaning than when the same power output is to be provided by nuclear or renewable sources, the latter are going to use tens to hundreds times more land surface for the same amount of power produced.
Greenpeace and some other environmental organizations have been criticized for distributing claims about emissions from nuclear power that are unsupported by the scientific data. Their influence has been attributed to "shocking" results of 2020 poll in France, where 69% of the respondents believed that nuclear power contributes to climate change. Greenpeace Australia for example claimed that "there’s no significant savings on carbon output" in nuclear power, which directly contradicts the
IPCC life-cycle analysis. In 2018 Greenpeace Spain ignored conclusions from a report by
University of Comillas report it procured, showing the lowest emissions in scenarios involving nuclear power, and instead supported an alternative scenario involving fossil fuels, with much higher emissions. Life-cycle land usage by nuclear power (including mining and waste storage, direct and indirect) is 100 m2/GWh which is of solar power and 1/10 of wind power. Land surface usage is the main reason for opposition against on-shore wind farms. In June 2020
Zion Lights, spokesperson of
Extinction Rebellion UK declared her support for nuclear energy as critical part of the energy mix along with renewable energy sources and called fellow environmentalists to accept that nuclear power is part of the "scientifically assessed solutions for addressing climate change". In July 2020 Good Energy Collective, the first women-only pressure group advocating nuclear power as part of the climate change mitigation solutions was formed in the US. In March 2021, 46 environmental organizations from the European Union wrote an open letter to the President of the European Commission calling to increase share of nuclear power as the most effective way of reducing EU's reliance on fossil fuels. The letter also condemned "multi-facetted misrepresentation" and "rigged information about nuclear, with opinion driven by fear" which results in the shutting down of stable, low-carbon nuclear power plants. A 2023 study calculated land surface usage of nuclear power at 0.15
km2/
TWh, the lowest of all energy sources. In May 2023, the Washington Post wrote, "Had Germany kept its nuclear plants running from 2010, it could have slashed its use of coal for electricity to 13 percent by now. Today’s figure is 31 percent... Already more lives might have been lost just in Germany because of air pollution from coal power than from all of the world’s nuclear accidents to date, Fukushima and Chernobyl included."
EU Taxonomy A comprehensive debate on the role of nuclear power continued since 2020 as part of regulatory work on
European Union Taxonomy of environmentally sustainable technologies. Low carbon intensity of nuclear power was not disputed, but opponents raised nuclear waste and thermal pollution as not sustainable element that should exclude it from the sustainable taxonomy. Detailed technical analysis was delegated to the
European Commission Joint Research Centre (JRC) which looked at all potential issues of nuclear power from scientific, engineering and regulatory point of view and in March 2021 published a 387-page report which concluded: The EU tasked two further expert commissions to validate JRC findings—the
Euratom Article 31 expert group on radiation protection and SCHEER (Scientific Committee on Health, Environmental and Emerging Risks). Both groups published their reports in July 2021, largely confirming JRC conclusions, with a number of topics that require further investigation. SCHEER also pointed out that JRC conclusion that nuclear power "does less harm" as the other (e.g. renewable) technologies against which it was compared is not entirely equivalent to the "do no significant harm" criterion postulated by the taxonomy. The JRC analysis of
thermal pollution doesn't fully take into account limited water mixing in shallow waters. The Article 31 group confirmed JRC findings: Also in July 2021 a group of 87 members of
European Parliament signed an open letter calling
European Commission to include nuclear power in the sustainable taxonomy following favourable scientific reports, and warned against anti-nuclear coalition that "ignore scientific conclusions and actively oppose nuclear power". In February 2022 European Commission published the Complementary Climate Delegated Act to the taxonomy, that set specific criteria under which nuclear power may be included in sustainable energy funding schemes. Inclusion of nuclear power and fossil gas in the taxonomy was justified by scientific reports mentioned above and based primarily on very large potential of nuclear power to decarbonize electricity production. For nuclear power, the Taxonomy covers research and development of new Generation IV reactors, new nuclear power plants built with Generation III reactors and life-time extension of existing nuclear power plants. All projects must satisfy requirements as to the safety, thermal pollution and waste management.
Effect on greenhouse gas emissions the mean value from nuclear power ranged from of total life cycle CO2 emissions with a median of An average nuclear power plant prevents emission of 2,000,000 metric tons of CO2, 5,200 metric tons of SO2 and 2,200 metric tons of NOx in a year as compared to an average fossil fuel plant. While nuclear power does not directly emit greenhouse gases, emissions occur, as with every source of energy, over a facility's life cycle: mining and fabrication of construction materials, plant construction, operation, uranium mining and milling, and plant decommissioning. The
Intergovernmental Panel on Climate Change found a median value of equivalent lifecycle carbon dioxide emissions per kilowatt hour (kWh) for nuclear power, being one of the lowest among all energy sources and comparable only with wind power. Data from the
International Atomic Energy Agency showed a similar result, with nuclear energy having the lowest emissions of any energy source when accounting for both direct and indirect emissions from the entire energy chain. stating, in part, that The statement was widely discussed in the scientific community, with voices both against and in favor. It has been also recognized that the life-cycle CO2 emissions of nuclear power will eventually increase once high-grade uranium ore is used up and lower-grade uranium needs to be mined and milled using fossil fuels, although there is controversy over when this might occur. As the nuclear power debate continues, greenhouse gas emissions are increasing. Predictions estimate that even with draconian emission reductions within the ten years, the world will still pass 650
ppm of carbon dioxide and a catastrophic average rise in temperature. Public perception is that renewable energies such as wind, solar, biomass and geothermal are significantly affecting global warming. All of these sources combined only supplied 1.3% of global energy in 2013 as of coal was burned annually. This "too little, too late" effort may be a mass form of
climate change denial, or an idealistic pursuit of
green energy. In 2015 an open letter from 65 leading biologists worldwide described nuclear power as one of the energy sources that are the most friendly to biodiversity due to its
high energy density and low environmental footprint: In response to 2016
Paris Agreement a number of countries explicitly listed nuclear power as part of their commitment to reduce greenhouse gas emissions. In June 2019, an open letter to "the leadership and people of Germany", written by almost 100 Polish environmentalists and scientist, urged Germany to "reconsider the decision on the final decommissioning of fully functional nuclear power plants" for the benefit of the fight against global warming. In 2020 a group of European scientists published an open letter to the European Commission calling for inclusion of nuclear power as "element of stability in carbon-free Europe". Also in 2020 a coalition of 30 European nuclear industry companies and research bodies published an open letter highlighting that nuclear power remains the largest single source of zero-emissions energy in European Union. In 2021 prime ministers of
Hungary,
France,
Czech Republic,
Romania,
Slovak Republic,
Poland and
Slovenia, signed an open letter to
European Commission calling for recognition of important role of nuclear power as the only non-intermittent
low-carbon energy source currently available at industrial scale in Europe. In 2021
UNECE described suggested pathways of building sustainable energy supply with increased role of
low-carbon nuclear power. In April 2021 US President's
Joe Biden Infrastructure Plan called for 100% of US electricity being generated from
low-carbon sources of which nuclear power would be a significant component.
IEA "Net Zero by 2050" pathways published in 2021 assume growth of nuclear power capacity by 104% accompanied by 714% growth of renewable energy sources, mostly solar power. In June 2021 over 100 organisations published a position paper for the
COP26 climate conference highlighting the fact that nuclear power is low-carbon dispatchable energy source that has been the most successful in reducing emissions from the energy sector. In August 2021
United Nations Economic Commission for Europe (UNECE) described nuclear power as important tool to mitigate climate change that has prevented 74 Gt of emissions over the last half century, that provides 20% of energy in Europe and 43% of low-carbon energy. Faced with increasing fossil gas prices and reopening of new coal and gas power plants, a number of European leaders questioned the anti-nuclear policies of Belgium and Germany. European Commissioner for the Internal Market
Thierry Breton described shutting down of operational nuclear power plants as depriving Europe of low-carbon energy capacity. Organizations such as Climate Bonds Initiative, Stand Up for Nuclear, Nuklearia and Mothers for Nuclear Germany-Austria-Switzerland are organizing periodic events in defense of the plants due to be closed.
High-level radioactive waste in
Washington The world's nuclear fleet creates about of high-level spent nuclear fuel each year. High-level radioactive waste management concerns management and disposal of highly
radioactive materials created during production of nuclear power. This requires the use of "geological disposal", or burial, due to the extremely long periods of time that
radioactive waste remain deadly to living organisms. Of particular concern are two
long-lived fission products,
technetium-99 (
half-life 220,000 years) and
iodine-129 (half-life 15.7 million years), which dominate spent nuclear fuel radioactivity after a few thousand years. The most troublesome
transuranic elements in spent fuel are
neptunium-237 (half-life two million years) and
plutonium-239 (half-life 24,000 years). However, many nuclear power by-products are usable as nuclear fuel themselves; extracting the usable energy producing contents from nuclear waste is called "
nuclear recycling". About 80% of the byproducts can be reprocessed and recycled back into nuclear fuel, negating this effect. The remaining high-level radioactive waste requires sophisticated treatment and management to successfully isolate it from the
biosphere. This usually necessitates treatment, followed by a long-term management strategy involving permanent storage, disposal or transformation of the waste into a non-toxic form. About 95% of nuclear waste by volume is classified as very low-level waste (VLLW) or low-level waste (LLW), with 4% being intermediate-level waste (ILW) and less than 1% being high-level waste (HLW). Governments around the world are considering a range of waste management and disposal options, usually involving deep-geologic placement, although there has been limited progress toward implementing long-term waste management solutions. This is partly because the timeframes in question when dealing with
radioactive waste range from 10,000 to millions of years, according to studies based on the effect of estimated radiation doses. at
Gorleben in northern Germany Since the fraction of a
radioisotope's atoms decaying per unit of time is inversely proportional to its half-life, the relative radioactivity of a quantity of buried human
radioactive waste would diminish over time compared to natural radioisotopes (such as the
decay chain of 120 trillion tons of thorium and 40 trillion tons of uranium which are
at relatively trace concentrations of parts per million each over the crust's 3 ton mass). For instance, over a timeframe of thousands of years, after the most active short half-life radioisotopes decayed, burying U.S. nuclear waste would increase the radioactivity in the top of rock and soil in the United States () by
approximately 0.1
parts per million over the cumulative amount of
natural radioisotopes in such a volume, although the vicinity of the site would have a far higher concentration of artificial radioisotopes underground than such an average.[broken link] Nuclear waste disposal is one of the most controversial facets of the nuclear power debate. Presently, waste is mainly stored at individual reactor sites and there are over 430 locations around the world where radioactive material continues to accumulate. Experts agree that centralized underground repositories which are well-managed, guarded, and monitored, would be a vast improvement. There is an international consensus on the advisability of storing nuclear waste in deep underground repositories, There are dedicated waste storage sites at the
Waste Isolation Pilot Plant in New Mexico and two in German salt mines, the
Morsleben Repository and the
Schacht Asse II. Public debate on the subject frequently focuses of nuclear waste only, ignoring the fact that existing
deep geologic repositories globally (including Canada and Germany) already exist and store highly toxic waste such as arsenic, mercury and cyanide, which, unlike nuclear waste, does not lose toxicity over time. Numerous media reports about alleged "radioactive leaks" from nuclear storage sites in Germany also confused waste from nuclear plants with low-level medical waste (such as irradiated X-ray plates and devices).
European Commission Joint Research Centre report of 2021 (see above) concluded: It estimated an average of 1.8 million lives saved worldwide by the use of nuclear power instead of fossil fuels between 1971 and 2009. The paper examined mortality levels per unit of electrical energy produced from fossil fuels (coal and natural gas) as well as nuclear power. Kharecha and Hansen assert that their results are probably conservative, as they analyze only deaths and do not include a range of serious but non-fatal respiratory illnesses, cancers, hereditary effects and heart problems, nor do they include the fact that fossil fuel combustion in developing countries tends to have a higher carbon and air pollution footprint than in developed countries. The authors also conclude that the emission of some of carbon dioxide equivalent have been avoided by nuclear power between 1971 and 2009, and that between 2010 and 2050, nuclear power could additionally avoid up to . A 2020 study on
Energiewende found that if Germany had postponed the nuclear phase out and phased out coal first it could have saved 1,100 lives and $12 billion in social costs per year. In 2020, the Vatican has praised "peaceful nuclear technologies" as significant factor to "alleviation of poverty and the ability of countries to meet their development goals in a sustainable way". ==Accidents and safety==