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Energy and Environment. Environmental Impacts of Nuclear Energy. Dr. Hassan Arafat Department of Chem. Eng. An-Najah University. (these slides were adopted, with modification, from Ms. Paulina Bohdanowicz , KTH Institute, Sweden). Europe – 35% of electricity production from nuclear

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Energy and Environment


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    1. Energy and Environment Environmental Impacts of Nuclear Energy Dr. Hassan Arafat Department of Chem. Eng. An-Najah University (these slides were adopted, with modification, from Ms. Paulina Bohdanowicz , KTH Institute, Sweden)

    2. Europe – 35% of electricity production from nuclear Lithuania – 79.9%

    3. Nuclear energy in the world On December 2004: 441 nuclear power plants in operation 25 nuclear power plants under construction (combined capacity of 20.9GW)

    4. Nuclear power plants in the world Source: InternationalNuclear Satefy Center Argonne National Laboratory, www.insc.anl.gov

    5. Nuclear reactors in Europe

    6. Nuclear power Source: European Environment Agency (EEA), Europe’s environment: the third assessment, Environmental assessment report, no.10, European Community, Copenhagen 2003

    7. Nuclear power Source: EEA 2003

    8. Potential causes of concern associated with the nuclear power Misuse of fissile and other radioactive material by terrorists Radioactivity (routine release, risk of accident, waste disposal) Proliferation of nuclear weapons Land pollution by mine tailings Health effects on uranium miners Source: Boyle G., Everett B., Ramage J., Energy systems and sustainability, Oxford 2003

    9. Environmental impacts of nuclear power Uranium mining uranium concentration ~3 mg/tonne of seawater, ~4 g/tonne of the granite, & up to 400 g/ tonne of coal naturally occurring uranium: more than 99 % of U-238 uranium-235 has an abundance of 0.71 %, and U-234 of 0.01% large amounts of rock have to be mined to obtain the required uranium - average ore grades at operating uranium mines range from 0.03 % to as high as 10 % uranium, but are most frequently less than 1 % radioactive contamination of the environment (radon and other gases) noise, dust, sulphur dioxide fumes overall relatively low polluting Source: UIC – Uranium and Nuclear Power Information center, http://www.uic.com.au/index.htm 2003

    10. Environmental impacts of nuclear power In-situ leaching - a leaching liquid solution - liquid ammonium carbonate, sodium carbonate, or sulphuric acid - forced through the underground ore body to dissolve the uranium => the uranium bearing solution - pumped back to the surface => precipitated => yellowcake U2O8 can only be used for ore situated in permeable rocks, which are confined by non-permeable rocks possibility that the solution of sulphuric acid, oxidant, and uranium migrate beyond the deposit and contaminate the groundwater the effects of the leaching liquid on the host rock of the deposit are unpredictable impossible to restore the natural condition in the leaching zone after finishing the leaching operation Source: UIC 2003

    11. Tailings up to 1000 tonnes of slurry residues per tonne of uranium extracted contain chemically and biologically harmful materials and radioactivity (20 times that of uranium) the tails are covered permanently with enough water, clay and soil to reduce both gamma radiation levels and radon emanation rates to levels near those naturally occurring in the region. A vegetation cover can then be established

    12. Environmental impacts of nuclear power Enrichment Yellowcake U2O8 gaseous diffusion enrichment, centrifugal enrichment, laser enrichment “enriched” uranium fuel – the content of the U-235 isotope from the natural level of 0.71% to about 3.5% or even more the enrichment process removes about 85% of the U-238 by separating gaseous uranium hexa-fluoride (UF6) into 2 streams: Enriched : Depleted : in the weight ratio 1:6 Depleted uranium – treated as waste Source: UIC 2003

    13. Environmental impacts of nuclear power Transport enriched UF6 - transported to a fuel fabrication plant => converted to uranium dioxide (UO2) powder and pressed into small pellets => inserted into thin zircalloy tubes to form fuel rods possibility of an accident with the transporting vehicle, catching of fires => a leakage to the surroundings contaminating water, soil and air UF6 – weakly radioactive but highly toxic and corrosive Facility construction Similar impacts as in case of fossil fuel power plant of similar size

    14. Environmental impacts of nuclear power Facility operation Thermal pollution into the environment (comparable with fossil fuel-fired plant) – sometimes utilised by district heating and agriculture Thermal efficiency: coal 20-40%, average for newer 32%; nuclear 29-38%, light water reactors – 34% A 8-10 oC increase in the temperature of the water - observed in the vicinity of the power plant

    15. Environmental impacts of nuclear power Facility operation -gaseous releases water vapour from cooling towers => heating and increasing humidity of the air around the plant cooling towers are often required to reduce the thermal impact if a river of a lake is the primary cooling source ventilation exhaust from buildings that do not have any processes with radioactivity – similar to any other building exhaust air diesel generators exhaust => the only source of GHG at a nuclear plant - the operation hours of diesels and turbines per year are very low gases and steam from the air ejectors => not radioactive at PWRs – unless leakage occurs; radioactive at BWRs - but passes through delay pipes, storage tanks & a hydrogen recombiner before being released

    16. Environmental impacts of nuclear power Facility operation -gaseous releases ventilation exhaust from buildings that do have processes with radioactivity gases removed from systems having radioactive fluids and gases (systems supporting the reactor cooling system) => removed, compressed and stored, periodically sampled and can only be released when the radioactivity is less than an acceptable level Small quantities of radioactivity may also be released by diffusion and through microscopic cracks in the fuel cladding (krypton-85, xenon-133, iodine-131)

    17. Environmental impacts of nuclear power Facility operation - liquid releases radioactive tritium, 3H, may be released in the discharged water non-radioactive - water that has been used to cool condenser, various heat exchangers (e.g. to cool oil, steam, water), used in the turbine-generator support processes, or that passes through the cooling towers, & water released from the steam generators => some or all of this water amount may be discharged to a river, sea or lake slightly radioactive very low levels of leakage may be allowed from the reactor cooling system to the secondary cooling system of the steam generator in any case where radioactive water may be released to the environment, it must be stored and radioactivity levels reduced through ion exchange processes below acceptable levels.

    18. Environmental impacts of nuclear power Facility operation – solid wastes radioactive waste (clothes, rags, wood) => compacted and placed in drums, drums must be thoroughly de-watered and put on special landfills radioactive spent resin (can be very radioactive) => shipped in specially designed containers spent fuel => stored underwater in large cooling pools at the plant, when storage has become limited, dry cask storage on-site may be used

    19. Environmental impacts of nuclear power Facility operation Low level waste (~600m3 – from a 1000MW PWR/annum) laboratory equipment, clothing, dust swept from laboratories, gases from fuel cladding stripping & other low irradiated bodies from plants and laboratories weak emitters of alpha, beta, and gamma particles, & generate little heat the disposal policy differs with the type of waste gaseous products - released to the atmosphere low activity liquids - piped out to sea solid products - buried Source: Ristinen R.A., Kraushaar J.J., Energy and the environment, USA 1999, Boyle et al. 2002

    20. Environmental impacts of nuclear power Facility operation Intermediate level waste (40m3) low level, long half-life wastes -fuel cladding, stream liquids, materials from decomissioning repositories – usually located around 300 meters underground Source: Ristinen R.A., Kraushaar J.J., Energy and the environment, USA 1999, Boyle et al. 2002

    21. Environmental impacts of nuclear power Facility operation high level waste (25m3) - spent fuel with long half-life (4m3), waste from reprocessing 1000 MWe reactor - ~30 tonnes of spent fuel => 1 tonne high-level waste isotopes of high activity and high heat generation (the fission products and actinides) 99.9% of the uranium and plutonium can be recovered Source: Ristinen, Kraushaar, 1999; Boyle et al. 2002

    22. Environmental impacts of nuclear power Facility operation – high level waste stored on-site until radioactivity decays to below 1% of original level (50yrs), placed in containers made of stainless steel or copper, then buried in special storages -– i.e. Yucca mountain A 1000 MWe reactor –total radioactivity in its spent fuel ~70MCi - a year after discharge ~14MCi – 10 years ~1.4MCi – 100 years ~2000Ci – 100 000 years high-level waste from reprocessing - incorporated into solid blocks of borosilicate glass - vitrification risk of accident and excessive radiation Source: Ristinen, Kraushaar, 1999; Boyle et al. 2002

    23. Nuclear waste in the US As of 2003, the United States accumulated about 49 000 metric tons of spent nuclear fuel from nuclear reactors. In addition, there will be about 22000 canisters of solid defense-related radioactive waste for future disposal in a repository all the nuclear waste produced to date in the United States stacked side-by-side, end-to-end, would cover an area about the size of a football field to a depth of about ten feet by the year 2035 this amount will increase to an estimated 105 000 metric tons Source: Office of Civilian Radioactive Waste Management, 2005, Ristinen, Kraushaar, 1999

    24. Nuclear waste storage sites in the US Source: OCRWM 2005

    25. Yukka Mountain project, US Under current regulations, a total of 70 000 metric tons of spent nuclear fuel and solid high level radioactive waste will be placed in Yucca Mountain – believed to be achieved by 2030. Spent fuel assemblies placed in cylindrical steel canisters 5m long, 2m in diameter + stabilising material Tunnels 350m below the surface, 222m above the water level On July 9, 2002, the U.S. Senate cast the final legislative vote approving the development of a repository at Yucca Mountain.The Yucca Mountain Project is currently focused on preparing an application to obtain a license from the U.S. Nuclear Regulatory Commission to construct a repository Source: Office of Civilian Radioactive Waste Management, www.ocrwm.doe.gov 2005; Ristinen, Kraushaar, 1999

    26. Yucca Mountain http://www.ocrwm.doe.gov/ Yucca Mountain: The Making of an Underground Laboratory Safe Passage: An Overview of Plans for the Railroad to Yucca Mountain (5min)

    27. Environmental impacts of nuclear power Reactor shutdown Heat pollution Immediately after shutdown, after the fission reactions have ceased, about 7% of normal thermal power generation remains, 1 hour after shutdown, about 1% of the normal reactor heat output – may be sufficient to melt the core. Source: Ristinen & Kraushaar 1999

    28. Environmental effects of radiation Agricultural areas Long-lived isotopes (Cs-137) Water Nucleides settle down with time Forest Reproductive functions Animals Mutations

    29. Health impacts of nuclear power • Catfish tumor

    30. Health impacts of nuclear power • Natural radiation: • Canada 0.5-1.1 mSv/yr, • Sydney 0.16-0.9 mSv/yr, • Perth 3.0mSv/yr, • Cornwall, UK 7mSv/yr, • India, Brazil, Sudan – up to 40mSv/yr, • Iran many times more • Average individual annual dose from natural and medical sources – 1.6mSv • Aircrew and frequent flyers – up to 5mSv/yr, • From nuclear power plants: UK citizens – 0.0003 mSv/yr • International Comission for Radiological Protection acceptable radiation levels: • 1 mSv/yr for members of the public • 20 mSv/yr averaged over 5 yrs for radiation workers who are required to work under closely monitored conditions Source: Boyle et al. 2003

    31. Health impacts of nuclear power • Single large doses in a short period • >10 Sv – death within hours or days • 1-10 Sv – radiation sickness and disability for weeks/months, ev. fatal • >1 Sv – symptoms decrease • 0.1 Sv – no immediately obvious effects • Long-term effects of lower doses • 1-2 cancers per 100 person-sieverts • Total no of genetic effects down to about the 10th generation – of the same order • Scientific evidence – no cancer risk or immediate effects at doses below 50 mSv in a short time, and about 100 mSv/yr • Beta particles, gamma rays and X-rays deliver a radiation dose of 1 Sv (sievert) in depositing 1J of energy per kg of tissue. • Alpha particles and neutrons deliver a radiation dose of 1 Sv in depositing 0.1 J of energy per kg of tissue. Source: Boyle et al. 2003

    32. Risks associated with nuclear accidents Source: Clemens P. L., Mohr R. R., Concepts in risk management, USA 2002

    33. Risk of accident April 26, 1986 – Chernobyl disaster, Pripiat, Ukraine Chernobyl – 200 plant personnel and firefighters – acute radiation sickness, out of them - 31 direct fatalities Source: Y. Arhus Bertrand

    34. The Chernobyl nuclear power plant following the accident in 1986

    35. Deposition after Chernobyl accident 135000 evacuated within 30km radius ~47000 eventual excess cancer deaths in Europe & Asia may occur in the next 50yrs (background level of cancer deaths – 500million) Source: Ristinen & Kraushaar 1999 Source: EEA 2003

    36. Occupational hazards of electricity production by fuel, no of deaths and diseases per GW-yr of output (including entire fuel cycle, excluding severe accidents) Source: Boyle et al. 2003

    37. Estimated deaths from power generation per GW-year output Source: Boyle et al. 2003

    38. The following countries are not included, due to a high level of uncertainty regarding their stockpiles: Israel (estimated warheads: 100-200); India (30-35), Pakistan (24-48); North Korea (?)

    39. Nuclear tests

    40. Positive impacts of nuclear power Not affected by the shortage of fossil fuels During operation do not emit CO2, CO or particulates into the atmosphere Source:

    41. Fossil fuels Air emissions Water pollution Thermal pollution Waste generation Impacts on human health Nuclear energy Thermal pollution Waste generation Risk of radioactivity release Environmental impacts of fossil fuels and nuclear energy And what about the renewables? Are they a solution to sustainable development? Are they environmentally neutral?