Environmental effects of nuclear power


Environmental effects of nuclear power

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 accident.

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 less than that of coal fired power plants [cite web
url=http://mb-soft.com/public2/powerplt.html
title=Global Warming from Electric Power Plants
author=C Johnson, Physicist
date=2007-09-26
language=English
] [ [http://www.world-nuclear.org/info/cooling_power_plants_inf121.html Cooling power plants World Nuclear Association] ] .

The cooling options are typically once-through cooling with river or sea water, pond cooling, or cooling towers. Many plants will have an artificial lake like the Shearon Harris Nuclear Power Plant or the South Texas Nuclear Generating Station. Shearon Harris makes use of a cooling tower but South Texas does not and discharges back into the lake. The North Anna Nuclear Generating Station is another example of direct use of 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). [Washington Post. [http://www.washingtonpost.com/wp-dyn/content/article/2007/11/27/AR2007112702224.html Happy in Their Haven Beside the Nuclear Plant] .] The environmental effects on the artificial lakes are often weighted in arguments against construction of new plants, and during droughts have drawn media attention. [NBC. [http://www.nbc17.com/midatlantic/ncn/news.apx.-content-articles-NCN-2007-11-29-0033.htmlhttp://www.nbc17.com/midatlantic/ncn/news.apx.-content-articles-NCN-2007-11-29-0033.html Dropping Lake Levels Affect Shearon Harris] ]

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.

One researcher believes that increasing sea water temperature has a detrimental effect on sea life. [ [http://www.powerstationeffects.co.uk/ Feature on impingement scope] ] [The Times, [http://www.timesonline.co.uk/tol/news/environment/article3740173.ece Nuclear plants sucking the sea life from British waters, researchers claim] ]

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) [The New York Times: [http://query.nytimes.com/gst/fullpage.html?res=9800EED61738F930A25752C1A9659C8B63&n=Top/News/Science/Topics/Fish%20and%20Other%20Marine%20Life State Proposal Would Reduce Fish Deaths At Indian Point] ] .

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. [SUGIYAMA KEN'ICHIRO (Hokkaido Univ.) et al. [http://sciencelinks.jp/j-east/article/200607/000020060706A0175205.php Nuclear District Heating: The Swiss Experience] ] . However, district heating with nuclear power plants is less common than with other modes of waste heat generation: because of either sditing 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. [IAEA, 1997: [http://www.iaea.org/Publications/Magazines/Bulletin/Bull392/39205082125.pdf Nuclear power applications: Supplying heat for homes and industries] ] .

During the 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. [The Observer. [http://observer.guardian.co.uk/world/story/0,,1833620,00.html Heatwave shuts down nuclear power plants] .] [cite web |url=http://www.csmonitor.com/2006/0810/p04s01-woeu.html |title=Nuclear power's green promise dulled by rising temps |publisher=The Christian Science Monitor |author=Susan Sachs |date=2006-08-10 |language=English ]

Radioactive waste

High level waste

Around 12 tonnes of high-level waste is produced per year per nuclear reactor. [ [http://www.oecdbookshop.org/oecd/display.asp?K=5KZK0CBTJQZT&CID=&LANG=en Nuclear Energy Data 2008] , OECD, p. 48 (the Netherlands, Borssele nuclear power plant)] 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.

Other waste

Moderate amounts of low-level waste are produced through a plant's 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. [NRC. [http://www.nrc.gov/reading-rm/doc-collections/nuregs/brochures/br0216/ Radioactive Waste: Production, Storage, Disposal (NUREG/BR-0216, Rev. 2)] ] Solid waste from the CVCS is combined with solid radwaste that comes from handling materials before it is buried off-site. [NRC. [http://www.nrc.gov/reading-rm/basic-ref/teachers/10.pdf Radioactive Waste Management] ]

Environmental effects of accidents

Some possible accidents at nuclear power plants pose a risk of severe environmental contamination. The Chernobyl accident 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.fact|date=July 2008

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 convert|50|mi|km of a nuclear power plant typically receive about 0.01 milli-rem per year [http://www.ans.org/pi/resources/dosechart/ ANS dosechart] [American Nuclear Society] ] . 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. Limits for the Canadian plants are shown below:

[ [http://wacid.kins.re.kr/DOCU/FILE/%EC%BA%90%EB%82%98%EB%8B%A4%EB%B0%A9%EC%B6%9C%EB%9F%89.pdf RADIOACTIVE EMISSIONS DATA FROM CANADIAN NUCLEAR GENERATING STATIONS 1988 TO 1997] ]

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 [http://www.reirs.com/effluent/ 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 comparsion). [ [http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html Coal Combustion - ORNL Review Vol. 26, No. 3&4, 1993 ] ] The Environmental Protection Agency estimates an added dose of 0.03 milli-rem per year for living within convert|50|mi|km of a coal plant and 0.009 milli-ren for a nuclear plant for yearly radiation dose estimation. [The EPA. [http://www.epa.gov/radiation/understand/calculate.html Calculate Your Radiation Dose] ]

Unlike coal-fired or oil-fired generation, Nuclear generation does not produce any amounts of sulfur dioxide, nitrogen oxides, mercury or other pollutants (pollution from fossil fuels is blamed for 24,000 early deaths each year in the U.S. aloneCite web|url=http://www.catf.us/publications/view/24|title=Dirty Air, Dirty Power: Mortality and Health Damage Due to Air Pollution from Power Plants|accessdate=2006-11-10|publisher=Clean Air Task Force|year=2004] ).

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). [ [http://www.npr.org/templates/story/story.php?storyId=6172217 National Public Radio (25 Apr. 2008): "Environmentalists rethink stance on nuclear power"] ] According to a 2007 story broadcast on "60 Minutes", [ [http://www.cbsnews.com/stories/2007/04/06/60minutes/main2655782.shtml France: Vive Les Nukes] accessed 23 July 2007] 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. [cite journal
url=
title=Full-energy-chain greenhouse-gas emissions: a comparison between nuclear power, hydropower, solar power and wind power
author=Joop F. van de Vate
publisher=International Journal of Risk Assessment and Management
date=2002
volume=3
number=1
pages=pp. 59–74
] 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).

Vattenfall comparative emissions study

A life cycle analysis centered around the Swedish Forsmark Nuclear Power Plant estimated carbon dioxide emissions at 3.10 g/kWh [Vattenfall 2004, Forsmark EPD for 2002 and SwedPower LCA data 2005.] and 5.05 g/kWh in 2002 for the Torness Nuclear Power Station. [ [http://www.uic.com.au/nip57.htm Energy Analysis of Power Systems] accessed 20 October 2007] 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. [ [http://www.eia.doe.gov/cneaf/electricity/page/co2_report/co2report.html#electric Electric Power Industry CO2 Emissions] accessed 20 October 2007]

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. [nuclearinfo.net. [http://nuclearinfo.net/Nuclearpower/WebHomeGreenhouseEmissionsOfNuclearPower Greenhouse Emissions of Nuclear Power] ]

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).Cite web|url=http://www.parliament.uk/documents/upload/postpn268.pdf
title=Carbon Footprint of Electricity Generation
accessdate=2007-07-13
year=2006
author=Parliamentary Office of Science and Technology
] 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.Cite web|url=http://news.bbc.co.uk/1/hi/sci/tech/4778344.stm|title='No Quick Fix' From Nuclear Power|accessdate=2006-11-10|publisher=BBC News|year=2006] [Cite web|url=http://www.sd-commission.org.uk/pages/060306.html|title=Is nuclear the answer?|accessdate=2006-12-22|publisher=Sustainable Development Commission|year=2006]

torm and Smith publication

In 2001, professors Jan Willem Storm van Leeuwen and Philip Smith released a study which argued that, though nuclear plants do not produce any carbon dioxide directly, the energy required for the rest of the nuclear fuel cycle (uranium mining, enrichment, transportation) and power plant life cycle (construction, maintenance, decommissioning) leads to significant carbon dioxide emissions, especially as usage of lower-grade uranium becomes necessary. [ [http://www.stormsmith.nl/report20050803/Chap_1.pdf Nuclear Power, The Energy Balance - Chapter 1 - The CO2-emission of the nuclear life-cycle] ]

The report by Jan Willem Storm van Leeuwen and Philip Smith, titled "Is Nuclear Power Sustainable?", was prepared for circulation during the April 2001 United Nations Commission on Sustainable Development meeting, and again during the continuation in Bonn in July 2001. The report concluded that nuclear power is not sustainable because of increasing energy inputs. The report has been widely cited in arguments against nuclear power.fact|date=July 2008

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.Cite web|url=http://www.stormsmith.nl/|title=Nuclear Power — The Energy Balance|accessdate=2006-11-10|year=2003|author=Jan Willem Storm van Leeuwen and Philip Smith] The study was strongly criticized by the World Nuclear Association (WNA), rebutted in 2003, then dismissed by the WNA in 2006 based on its own life-cycle-energy calculation (with comparisons). 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 wind power. [ [http://www.world-nuclear.org/info/inf100.html Energy Balances and CO2 Implications] accessed 23 July 2007] [ [http://www.world-nuclear.org/info/inf11.html Energy Analysis of Power Systems] accessed 23 July 2007]

Other reports

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.cite web
url=http://www.oxfordresearchgroup.org.uk/publications/briefing_papers/pdf/secureenergy.pdf
title=Secure Energy? Civil nuclear power, security and global warming.
date=2007-03
author=Frank Barnaby and James Kent
publisher=Oxford Research Group
language=English
]

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 Commons, 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. [cite web |url=http://web.archive.org/web/20070207022344/http://www.oxfordresearchgroup.org.uk/programmes/nuclearissues/EAC210905.pdf |title=Memorandum by Oxford Research Group
accessdate=2007-03-26, since taken down |last=Barnaby
first=Frank |authorlink= |coauthors=Barnham, Keith; Savidge, Malcolm
date=2005-09-21|year= |month= |format= |work= |publisher= |pages=p.9 |language= |archiveurl= |archivedate= |quote=
]

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. [ [http://www.nei.org/index.asp?catnum=2&catid=260 "Hydropower-Internalised Costs and Externalised Benefits"] ; Frans H. Koch; International Energy Agency (IEA)-Implementing Agreement for Hydropower Technologies and Programmes; Ottawa, Canada, 2000]

Water use

Nuclear plants require more, but not significantly more, cooling water than fossil-fuel power plants due to their slightly lower generation efficiencies.

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. [http://www.sciencealert.com.au/opinions/20072910-16508.html Nuclear power and water scarcity] , ScienceAlert, 28 October 2007, Retrieved 2008-08-08] The effect on prices of uranium should be considered.

ee also

*Ecological footprint
*Environmental concerns with electricity generation

References

External links

* [http://www.ceem.unsw.edu.au/content/userDocs/NukesSocialAlternativesMD.pdf Is nuclear energy a possible solution to global warming?]
*Photo essay : [http://www.peakoil.org.au/news/index.php?does_nuclear_energy_produce_no_co2.htm Does nuclear energy produce no CO2 ?]
*PowerPoint : [http://www.peakoil.org.au/does_nuclear_energy_produce_no_co2.ppt Does nuclear energy produce no CO2 ?]
* [http://www.cosmosmagazine.com/node/1955 Nuclear energy becoming less sustainable]


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