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Nuclear power processes involving the environment; mining, enrichment, waste heat, and geological disposal.


Nuclear power, as with all power sources, has an effect on the environment through the nuclear fuel cycle, through operation, and (in Europe) from the lingering effects of the Chernobyl accidentmarker.

Waste heat

The North Anna plant uses direct exchange cooling into an artificial lake.
As with any thermal power station, nuclear plants exchange 60 to 70% of their thermal energy by cycling with a body of water or by evaporating water through a cooling tower. This thermal efficiency is slightly less than that of coal fired power plants.

The cooling options are typically once-through cooling with river or sea water, pond cooling, or cooling towers. Many plants have an artificial lake like the Shearon Harris Nuclear Power Plantmarker or the South Texas Nuclear Generating Stationmarker. Shearon Harris uses a cooling tower but South Texas does not and discharges back into the lake. The North Anna Nuclear Generating Stationmarker uses a cooling pond or artificial lake, which at one spot near the plant's discharge is often about 30 degrees warmer than in the other parts of the lake or in normal lakes (this is cited as an attraction of the area by some residents). The environmental effects on the artificial lakes are often weighted in arguments against construction of new plants, and during droughts have drawn media attention.

The Turkey Point Nuclear Generating Stationmarker is credited with helping the conservation status of the American Crocodile, largely an effect of the waste heat produced.

The Indian Pointmarker nuclear power plant in New Yorkmarker is in a hearing process to determine if a cooling system other than river water will be necessary (conditional upon the plants extending their operating licenses).

It is possible to use waste heat in cogeneration applications such as district heating. The principles of cogeneration and district heating with nuclear power are the same as any other form of thermal power production. One use of nuclear heat generation was with the Ågesta Nuclear Power Plantmarker in Sweden. In Switzerland, the Beznau Nuclear Power Plantmarker provides heat to about 20,000 people.. However, district heating with nuclear power plants is less common than with other modes of waste heat generation: because of either siting regulations and/or the NIMBY effect, nuclear stations are generally not built in densely populated areas. Waste heat is more commonly used in industrial applications.

During Europe's 2003 and 2006 heat waves, French, Spanish and German utilities had to secure exemptions from regulations in order to discharge overheated water into the environment. Some nuclear reactors shut down.

Uranium mining can use large amounts of water - for example, the Roxby Downs mine in South Australia uses 35 million litres of water each day and plans to increase this to 150 million litres per day.

Radioactive waste

High level waste

Around 300 tons of high-level waste are produced per month per nuclear reactor. Currently most spent nuclear fuel outside the U.S. is reprocessed for the useful components, leaving only a much smaller volume of short half-life waste to be stored. In the U.S. reprocessing is currently prohibited by executive order, and the spent nuclear fuel is therefore stored in dry cask storage facilities (this has the disadvantage of keeping the long-lived isotopes with the other waste, thus greatly extending the half-life of the waste).

Several methods have been suggested for final disposal of high-level waste, including deep burial in stable geological structures, transmutation, and removal to space. Currently, monitored retrieveable storage is the option being most prepared.

Some nuclear reactors, such as the Integral Fast Reactor, have been proposed that use a different nuclear fuel cycle that avoids producing waste containing long-lived radioactive isotopes or actually "burns" those isotopes from other plants, via transmutation into elements with lower radioactivity.

According to anti-nuclear organizations and current public opinion in the US, rendering nuclear waste harmless is not being done satisfactorily and it remains a hazard for anywhere between a few years to many thousands of years, depending on the particular isotopes. However, the same organizations usually oppose, and lobby against, processing the waste to reduce its radioactivity and longevity, and also oppose unproven attempts at isolating the residual waste from the environment.

The length of time waste has to be stored is controversial because there is a question of whether one should use the original ore or surrounding rock as a reference for safe levels. Anti-nuclear organizations tend to favor using normal soil as a reference, in contrast to pro-nuclear organizations who tend to argue that geologically disposed waste can be considered safe once it is no more radioactive than the uranium ore it was produced from.

Other waste

Moderate amounts of low-level waste are produced through chemical and volume control system (CVCS). This includes gas, liquid, and solid waste produced through the process of purifying the water through evaporation. Liquid waste is reprocessed continuously, and gas waste is filtered, compressed, stored to allow decay, diluted, and then discharged. The rate at which this is allowed is regulated and studies must prove that such discharge does not violate dose limits to a member of the public (see radioactive effluent emissions).

Solid waste can be disposed of simply by placing it where it will not be disturbed for a few years. There are three low-level waste disposal sites in the United States in South Carolina, Utah, and Washington. Solid waste from the CVCS is combined with solid radwaste that comes from handling materials before it is buried off-site.

Environmental effects of accidents

Some possible accidents at nuclear power plants pose a risk of severe environmental contamination. The Chernobyl accidentmarker at an RBMK reactor (which did not have the usually-required containment building) released large amounts of radioactive contamination, killing many and rendering an area of land unusable to humans for an indeterminate period. The habitability of the area for animals, however, has been less clear. Some researchers have claimed to have detected depressed numbers of insects and spiders, while others have claimed that wildlife has flourished due to the absence of humans.

Contrast of radioactive accident emissions with industrial emissions

Proponents argue that the problems of nuclear waste "do not come anywhere close" to approaching the problems of fossil fuel waste. A 2004 article from the BBC states: "The World Health Organization (WHO) says 3 million people are killed worldwide by outdoor air pollution annually from vehicles and industrial emissions, and 1.6 million indoors through using solid fuel." In the U.S. alone, fossil fuel waste kills 20,000 people each year. A coal power plant releases 100 times as much radiation as a nuclear power plant of the same wattage. It is estimated that during 1982, US coal burning released 155 times as much radioactivity into the atmosphere as the Three Mile Islandmarker incident. The World Nuclear Association provides a comparison of deaths due to accidents among different forms of energy production. In their comparison, deaths per TW-yr of electricity produced from 1970 to 1992 are quoted as 885 for hydropower, 342 for coal, 85 for natural gas, and 8 for nuclear.

Radioactive effluent emissions

Most commercial nuclear power plants release gaseous and liquid radiological effluents into the environment as a byproduct of the Chemical Volume Control System, which are monitored in the US by the EPA and the NRC. Civilians living within of a nuclear power plant typically receive about 0.01 milli-rem per year. For comparison, the average person living at or above sea level receives at least 26 milli-rem from cosmic radiation.

The total amount of radioactivity released through this method depends on the power plant, the regulatory requirements, and the plant's performance. Atmospheric dispersion models combined with pathway models are employed to accurately approximate the dose to a member of the public from the effluents emitted. Effluent monitoring is conducted continuously at the plant.

Limits for the Canadian plants are shown below:

Regulatory limits on Radioactive Effluents from Canadian Nuclear Power Plants
Effluent Tritium Iodine-131 Noble Gases Particulates Carbon-14
Units (TBqb × 104) (TBq) (TBq-MeVc × 104) (TBq) (TBq × 103)
Point Lepreau Nuclear Generating Stationmarker 43.0 9.9 7.3 5.2 3.3
Bruce Nuclear Generating Stationmarker A 38.0 1.2 25.0 2.7 2.8
Bruce B 47.0 1.3 61.0 4.8 3.0
Darlington 21.0 0.6 21.0 4.4 1.4
Pickering Nuclear Generating Stationmarker A 34.0 2.4 8.3 5.0 8.8
Pickering B 34.0 2.4 8.3 5.0 8.8
Gentilly-2 44.0 1.3 17.0 1.9 0.91


Effluent emissions for Nuclear power in the United States are regulated by 10 CFR 50.36(a)(2). For detailed information, consult the Nuclear Regulatory Commission's database.

Boron letdown

Towards the end of each cycle of operation (typically 18 months to two years in length), each pressurized water reactor reduces the amount of boron in its primary coolant system (the water that flows past and cools the nuclear reactor core). As a consequence, some of this irradiated boron is discharged from the plant and into whatever body of water the plant's cooling water is drawn from. The maximum amount of radioactivity permitted in each volume of discharge is tightly regulated (see above).

Comparison to coal-fired generation

In terms of net radioactive release, the National Council on Radiation Protection and Measurements (NCRP) estimated the average radioactivity per short ton of coal is 17,100 millicuries/4,000,000 tons. With 154 coal plants in the United States, this amounts to emissions of 0.6319 TBq per year for a single plant, which still does not directly compare to the limits on nuclear plants (see above table) because coal emissions contain long lived isotopes and have different dispersion and intake pathways.

In terms of dose to a human living nearby, it is sometimes cited that coal plants release 100 times the radioactivity of nuclear plants. This comes from NCRP Reports No. 92 and No. 95 which estimated the dose to the population from 1000 MWe coal and nuclear plants at 490 person-rem/year and 4.8 person-rem/year respectively (a typical Chest x-ray gives a dose of about 6 milli-rem for comparison). The Environmental Protection Agency estimates an added dose of 0.03 milli-rem per year for living within of a coal plant and 0.009 milli-ren for a nuclear plant for yearly radiation dose estimation.

Unlike coal-fired or oil-fired generation, nuclear power generation does not directly produce any sulfur dioxide, nitrogen oxides, or mercury (pollution from fossil fuels is blamed for 24,000 early deaths each year in the U.S. alone). However, as with all energy sources, there is some pollution associated with support activities such as manufacturing and transportation.

Carbon dioxide

Nuclear power operation does not produce carbon dioxide, leading the nuclear power industry and some environmentalists, such as Greenpeace co-founder Patrick Moore, to advocate it to reduce greenhouse gas emissions (which contribute to global warming). According to a 2007 story broadcast on 60 Minutes, nuclear power gives France the cleanest air of any industrialized country, and the cheapest electricity in all of Europe.

A fair comparison of the climate impacts from different energy sources can be made only by accounting for the emissions of all relevant greenhouse gases (GHGs) from the full energy chain (FENCH) of the energy sources. Like any power source (including renewables like wind and solar energy), the facilities to produce and distribute the electricity require energy to build and subsequently decommission. Mineral ores must be collected and processed to produce nuclear fuel. These processes either are directly powered by diesel and gasoline engines, or draw electricity from the power grid, which may be generated from fossil fuels. Life cycle analyses assess the amount of energy consumed by these processes (given today's mix of energy resources) and calculate, over the lifetime of a nuclear power plant, the amount of carbon dioxide saved (related to the amount of electricity produced by the plant) vs. the amount of carbon dioxide used (related to construction and fuel acquisition). Some studies have found that due to thermodynamic limitations, nuclear power may not be able to expand quickly enough to reduce greenhouse gas emissions .

Sovacool life cycle study survey



A 2008 meta analysis, "Valuing the Greenhouse Gas Emissions from Nuclear Power: A Critical Survey," looked at 103 life cycle studies of greenhouse gas-equivalent emissions for nuclear power plants. The studies surveyed included the 1997 Vattenfall comparative emissions study, among others. Sovacool's analysis calculated that the mean value of emissions over the lifetime of a nuclear power plant is 66g/kWh. Biomass, solar, and hydroelectric were 41g/kWh, 13g/kWh, and 9-10g/kWh respectively.

UK Parliamentary Office Study

In a study conducted in 2006 by the UK's Parliamentary Office of Science and Technology (POST), nuclear power's lifecycle was evaluated to emit the least amount of carbon dioxide (very close to wind power's lifecycle emissions) when compared to the other alternatives (fossil fuel, coal, and some renewable energy including biomass and PV solar panels). In 2006, a UK government advisory panel, The Sustainable Development Commission, concluded that if the UK's existing nuclear capacity were doubled, it would provide an 8% decrease in total UK CO2 emissions by 2035. This can be compared to the country's goal to reduce greenhouse gas emissions by 60 % by 2050. As of 2006, the UK government was to publish its official findings later in the year.

Vattenfall comparative emissions study

A life cycle analysis centered around the Swedish Forsmark Nuclear Power Plantmarker estimated carbon dioxide emissions at 3.10 g/kWh and 5.05 g/kWh in 2002 for the Torness Nuclear Power Stationmarker. This compares to 11 g/kWh for hydroelectric power, 950 g/kWh for installed coal, 900 g/kWh for oil and 600 g/kWh for natural gas generation in the United States in 1999.

The Vattenfall study found Nuclear, Hydro, and Wind to have far less greenhouse emissions than other sources represented.
The Swedish utility Vattenfall studied full life cycle emissions of nuclear, hydro, coal, gas, solar cell, peat, and wind, which the utility uses to produce electricity. The study concluded that nuclear power produced the smallest amount of CO2 of any of their electricity sources. Nuclear power produced 3.3 g/kWh of carbon dioxide, compared to 400 for natural gas and 700 for coal.

Storm and Smith publication

In 2001, Jan Willem Storm van Leeuwen and Philip Smith released a study Nuclear Power, The Energy Balance - Chapter 1 - The CO2-emission of the nuclear life-cycle, titled Is Nuclear Power Sustainable?, which was prepared for circulation during the April 2001 United Nations Commission on Sustainable Development meeting, and again during the continuation in Bonnmarker in July 2001. The report claims carbon dioxide emissions from nuclear power per kilowatt hour could range from 20% to 120% of those for natural gas-fired power stations depending on the availability of high grade ores.The report concluded that nuclear power is not sustainable because of increasing energy inputs as lower-grade ores are used.

The study was strongly criticized by the World Nuclear Association (WNA), updated in 2002 and 2005 by Storm van Leeuwen, then dismissed again by the WNA in 2006 based on its own life-cycle-energy calculation. The WNA also listed several other independent life cycle analyses which show similar emissions per kilowatt-hour from nuclear power and from renewables such as hydro and wind power.

Energy Cannibalism

A professor at Queen's Universitymarker, Joshua Pearce published a paper in the International Journal of Nuclear Governance, Economy and Ecology titled Thermodynamic limitations to nuclear energy deployment as a greenhouse gas mitigation technology, which applied his proposed concept of Energy cannibalism to nuclear power. He suggested that, with a representative energy payback time from Jan Willem Storm van Leeuwen (5.5 to 92 years for the US energy mix, 1.5 to 12 years for the European energy mix with an ore grade of 0.1%) of 10 years, nuclear power will have a growth limit of 10% without "cannibalizing" other energy sources.

Other reports

An Australian life-cycle report in 2008 found a greenhouse gas intensity of nuclear power to be around 60 g CO2-e/kWhel for light water reactors, and around 65 g CO2-e/kWhelfor heavy water reactors.

A 2007 report by Frank Barnaby and James Kent lists several FENCH emissions of CO2 vary between 10 and 130 grams per kWh. Methodology from the Storm and Smith publication is cited, and similar conclusions are drawn from this literature study.

On 21 September 2005 the Oxford Research Group published a report, in the form of a memorandum to a committee of the British House of Commonsmarker, in which Storm repeated his results that, while nuclear plants do not generate carbon dioxide while they operate, the other steps necessary to produce nuclear power, including the mining of uranium and the storing of waste, result in substantial amounts of carbon dioxide pollution.

In 2000, Frans H. Koch of the International Energy Agency reported that, although it is correct that the nuclear life cycle produces greenhouse gases, these emissions are actually less than the life cycle emissions of some renewables, like solar and wind, and drastically less than fossil fuels.

See also



References

  1. Cooling power plants World Nuclear Association
  2. Washington Post. Happy in Their Haven Beside the Nuclear Plant.
  3. NBC. Dropping Lake Levels Affect Shearon Harris
  4. The New York Times: State Proposal Would Reduce Fish Deaths At Indian Point
  5. SUGIYAMA KEN'ICHIRO (Hokkaido Univ.) et al. Nuclear District Heating: The Swiss Experience
  6. IAEA, 1997: Nuclear power applications: Supplying heat for homes and industries
  7. The Observer. Heatwave shuts down nuclear power plants.
  8. Nuclear power and water scarcity, ScienceAlert, 28 October 2007, Retrieved 2008-08-08
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  10. Greenpeace Website
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  14. NRC. Radioactive Waste Management
  15. BBC News. Chernobyl 'shows insect decline'. March 18, 2009.
  16. Nuclear proliferation through coal burning — Gordon J. Aubrecht, II, Ohio State University
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  19. Coal Combustion - ORNL Review Vol. 26, No. 3&4, 1993
  20. The EPA. Calculate Your Radiation Dose
  21. National Public Radio (25 Apr. 2008): Environmentalists rethink stance on nuclear power
  22. France: Vive Les Nukes accessed 23 July 2007
  23. Benjamin K. Sovacool. [Valuing the greenhouse gas emissions from nuclear power: A critical survey http://www.nirs.org/climate/background/sovacool_nuclear_ghg.pdf]. Energy Policy. 2008.
  24. Vattenfall 2004, Forsmark EPD for 2002 and SwedPower LCA data 2005.
  25. Uranium Information Centre. Energy Analysis of Power Systems accessed 20 October 2007
  26. Electric Power Industry CO2 Emissions accessed 20 October 2007
  27. nuclearinfo.net. Greenhouse Emissions of Nuclear Power
  28. Energy Balances and CO2 Implications accessed 23 July 2007
  29. Energy Analysis of Power Systems accessed 23 July 2007
  30. Pearce, J. M. “ Thermodynamic Limitations to Nuclear Energy Deployment as a Greenhouse Gas Mitigation Technology”, International Journal of Nuclear Governance, Economy and Ecology 2(1), pp. 113-130, 2008. Full text
  31. Lenzen M. (2008) Life cycle energy and greenhouse gas emissions of nuclear energy: A review. Energy Conversion and Management 49, 2178-99.
  32. "Hydropower-Internalised Costs and Externalised Benefits"; Frans H. Koch; International Energy Agency (IEA)-Implementing Agreement for Hydropower Technologies and Programmes; Ottawa, Canada, 2000


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