Environmental impact of nuclear power: Difference between revisions
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Chernobyl was one of the rare [[RBMK]]-type reactors, which were so large that they did not have the usually-required [[containment building]]. The mitigating effect that the containment building would have had has not been proven. |
Chernobyl was one of the rare [[RBMK]]-type reactors, which were so large that they did not have the usually-required [[containment building]]. The mitigating effect that the containment building would have had has not been proven. |
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kenny was born on his birthday |
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==See also== |
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*[[Church Rock Uranium Mill Spill]] |
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*[[Ecological footprint]] |
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*[[Environmental concerns with electricity generation]] |
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*[[International Nuclear Event Scale]] |
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*[[Waste Isolation Pilot Plant]] |
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==References== |
==References== |
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Revision as of 19:46, 24 May 2010
Nuclear power, as with all power sources, has an effect on the environment through the nuclear fuel cycle, through operation, and potentially through the disposal of waste.
Waste heat
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 greater than that of coal fired power plants[1][2].
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 Plant or the South Texas Nuclear Generating Station. Shearon Harris uses a cooling tower but South Texas does not and discharges back into the lake. The North Anna Nuclear Generating Station 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).[3] The environmental effects on the artificial lakes are often weighted in arguments against construction of new plants, and during droughts have drawn media attention.[4]
The Turkey Point Nuclear Generating Station is credited with helping the conservation status of the American Crocodile, largely an effect of the waste heat produced.[5]
The Indian Point nuclear power plant in New York 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).[6]
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 Plant in Sweden. In Switzerland, the Beznau Nuclear Power Plant provides heat to about 20,000 people.[7]. 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.[8]
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.[9][10]
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.[11]
Radioactive waste
High level waste
Around 20-30 tons of high-level waste are produced per month per nuclear reactor.[12] 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.[13][14][15]
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.[16] Solid waste from the CVCS is combined with solid radwaste that comes from handling materials before it is buried off-site.[17]
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.[18][19] 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."[20] In the U.S. alone, fossil fuel waste kills 20,000 people each year.[21] A coal power plant releases 100 times as much radiation as a nuclear power plant of the same wattage.[22] It is estimated that during 1982, US coal burning released 155 times as much radioactivity into the atmosphere as the Three Mile Island incident.[23] 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.[24]
Radioactive effluents
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 50 miles (80 km) of a nuclear power plant typically receive about 0.01 milli-rem per year[25]. For comparison, the average person living at or above sea level receives at least 26 milli-rem from cosmic radiation.[25]
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:
| Effluent | Tritium | Iodine-131 | Noble Gases | Particulates | Carbon-14 |
|---|---|---|---|---|---|
| Units | (TBqb × 104) | (TBq) | (TBq-MeVc × 104) | (TBq) | (TBq × 103) |
| Point Lepreau Nuclear Generating Station | 43.0 | 9.9 | 7.3 | 5.2 | 3.3 |
| Bruce Nuclear Generating Station 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 Station 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
 | This article needs attention from an expert in Energy. Please add a reason or a talk parameter to this template to explain the issue with the article. (February 2009) |
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).
| Country | Limit (Bq/L) |
|---|---|
| Australia | 76,103 |
| Finland | 30,000 |
| WHO | 10,000 |
| Switzerland | 10,000 |
| Russia | 7,700 |
| Ontario, Canada | 7,000 |
| United States | 740 |
| European Union | 1001 |
| California Public Health Goal | 14.8 |
Tritium
Tritium is a radioactive isotope of Hydrogen that emits a low-energy beta particle and is usually measured in Becquerels per Liter (Bq/L). Tritium becomes dissolved in ordinary water when released from a nuclear plant. The primary concern for Tritium release is the presence in drinking water, in addition to biological magnification leading to Tritium in crops and animals consumed for food.[27]
Legal concentration limits have differed greatly to place to place (see table right). For example, in June 2009 the Ontario Ministry of Environment was considering lowering the limit from 7,000 Bq/L to 20 Bq/L.[28] According to the NRC, Tritium is the least dangerous radionuclides because it emits very weak radiation and leaves the body relatively quick. The amount released by any given plant also varies greatly; the total release for plants in the United States in 2003 was at least counted to be 0 and at most 2,080 Curries.
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).[29] The Environmental Protection Agency estimates an added dose of 0.03 milli-rem per year for living within 50 miles (80 km) of a coal plant and 0.009 milli-ren for a nuclear plant for yearly radiation dose estimation.[30]
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[31]). However, as with all energy sources, there is some pollution associated with support activities such as manufacturing and transportation.
Greenhouse Gas Emissions
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).[32] According to a 2007 story broadcast on 60 Minutes,[33] 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.[34] 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. Also, although nuclear power plants don't produce greenhouse gases while in operation, the mineral ores must be collected and processed to produce nuclear fuel - these processes either are powered by diesel and gasoline engines or draw electricity from the power grid. 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). Most comparisons of life cycle analysis (LCA) of carbon dioxide emissions show nuclear power as comparable to renewable energy sources.[35][36]
Some studies have found that due to thermodynamic limitations, nuclear power may not be able to expand quickly enough to reduce greenhouse gas emissions [37][38].
Energy Cannibalism
A professor at Queen's University, 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 (controversial) 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. [39]
Environmental effects of accidents
The worst possible accidents at nuclear power plants pose a risk of severe environmental contamination.
Current effects from the Chernobyl disaster
The Chernobyl accident 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.[40]
Chernobyl was one of the rare RBMK-type reactors, which were so large that they did not have the usually-required containment building. The mitigating effect that the containment building would have had has not been proven.
kenny was born on his birthday
References
- ^ C Johnson, Physicist (2007-09-26). "Global Warming from Electric Power Plants".
- ^ Cooling power plants World Nuclear Association
- ^ Washington Post. Happy in Their Haven Beside the Nuclear Plant.
- ^ NBC. Dropping Lake Levels Affect Shearon Harris
- ^ ""About Turkey Point"". FPL.com. Florida Power & Light. Retrieved 2007-07-25.
- ^ The New York Times: State Proposal Would Reduce Fish Deaths At Indian Point
- ^ SUGIYAMA KEN'ICHIRO (Hokkaido Univ.) et al. Nuclear District Heating: The Swiss Experience
- ^ IAEA, 1997: Nuclear power applications: Supplying heat for homes and industries
- ^ The Observer. Heatwave shuts down nuclear power plants.
- ^ Susan Sachs (2006-08-10). "Nuclear power's green promise dulled by rising temps". The Christian Science Monitor.
- ^ Nuclear power and water scarcity, ScienceAlert, 28 October 2007, Retrieved 2008-08-08
- ^ Nuclear Energy Data 2008, OECD, p. 48 (the Netherlands, Borssele nuclear power plant)
- ^ Greenpeace Website
- ^ NRDC Website
- ^ Public Citizen Website
- ^ NRC. Radioactive Waste: Production, Storage, Disposal (NUREG/BR-0216, Rev. 2)
- ^ NRC. Radioactive Waste Management
- ^ David Bodansky. "The Environmental Paradox of Nuclear Power". American Physical Society. Retrieved 2008-01-31.
(reprinted from Environmental Practice, vol. 3, no. 2 (June 2001), pp.86–88 {Oxford University Press))
- ^ "Some Amazing Facts about Nuclear Power". 2002. Retrieved 2008-01-31.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help); Unknown parameter|month=ignored (help) - ^ Alex Kirby (13 December 2004,). ""Pollution: A life and death issue"". BBC News. Retrieved 2008-01-31.
{{cite web}}: Check date values in:|date=(help); Italic or bold markup not allowed in:|publisher=(help)CS1 maint: extra punctuation (link) - ^ Don Hopey (June 29, 2005). ""State sues utility for U.S. pollution violations"". Pittsburgh Post-Gazette. Retrieved 2008-01-31.
{{cite web}}: Italic or bold markup not allowed in:|publisher=(help) - ^ Alex Gabbard. "Coal Combustion: Nuclear Resource or Danger". Oak Ridge National Laboratory. Retrieved 2008-01-31.
{{cite web}}: Cite has empty unknown parameter:|month=(help) - ^ Nuclear proliferation through coal burning — Gordon J. Aubrecht, II, Ohio State University
- ^ "Safety of Nuclear Power Reactors".
- ^ a b ANS dosechart [American Nuclear Society]
- ^ RADIOACTIVE EMISSIONS DATA FROM CANADIAN NUCLEAR GENERATING STATIONS 1988 TO 1997
- ^ Nuclear Regulatory Commission. Groundwater Contamination (Tritium) at Nuclear Plants.
- ^ Canadian Nuclear Safety Commission. Information Updates: Tritium in drinking water
- ^ Coal Combustion - ORNL Review Vol. 26, No. 3&4, 1993
- ^ The EPA. Calculate Your Radiation Dose
- ^ "Dirty Air, Dirty Power: Mortality and Health Damage Due to Air Pollution from Power Plants". Clean Air Task Force. 2004. Retrieved 2006-11-10.
- ^ National Public Radio (25 Apr. 2008): Environmentalists rethink stance on nuclear power
- ^ France: Vive Les Nukes accessed 23 July 2007
- ^ Joop F. van de Vate (2002). "Full-energy-chain greenhouse-gas emissions: a comparison between nuclear power, hydropower, solar power and wind power". 3 (1). International Journal of Risk Assessment and Management: pp. 59–74.
{{cite journal}}:|pages=has extra text (help); Cite journal requires|journal=(help) - ^ Energy Balances and CO2 Implications World Nuclear Association November 2005
- ^ Life-cycle emissions analyses
- ^ Joshua M. Pearce (2008). "Thermodynamic limitations to nuclear energy deployment as a greenhouse gas mitigation technology". 2 (1). International Journal of Nuclear Governance, Economy and Ecology: pp. 113–130.
{{cite journal}}:|pages=has extra text (help); Cite journal requires|journal=(help) - ^ Joshua M. Pearce (2009). "Optimizing Greenhouse Gas Mitigation Strategies to Suppress Energy Cannibalism" (PDF). 2nd Climate Change Technology Conference.
{{cite journal}}: Cite journal requires|journal=(help) - ^ 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
- ^ BBC News. Chernobyl 'shows insect decline'. March 18, 2009.
External links
- Is nuclear energy a possible solution to global warming?
- Photo essay : Does nuclear energy produce no CO2 ?
- PowerPoint : Does nuclear energy produce no CO2?
- Nuclear energy becoming less sustainable
