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Environmental Science: Toward a Sustainable Future Richard T. Wright

Environmental Science: Toward a Sustainable Future Richard T. Wright. Chapter 13. Energy from Nuclear Power PPT by Clark E. Adams. Energy from Nuclear Power. Nuclear energy in perspective How nuclear power works The hazards and costs of nuclear power facilities More advanced reactors

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Environmental Science: Toward a Sustainable Future Richard T. Wright

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  1. Environmental Science: Toward a Sustainable FutureRichard T. Wright Chapter 13 Energy from Nuclear Power PPT by Clark E. Adams

  2. Energy from Nuclear Power • Nuclear energy in perspective • How nuclear power works • The hazards and costs of nuclear power facilities • More advanced reactors • The future of nuclear power

  3. Nuclear Energy in Perspective

  4. Nuclear Energy in Perspective

  5. Nuclear Energy in Perspective

  6. How Nuclear Power Works • From mass to energy • Comparing nuclear power to coal power

  7. From Mass to Energy http://www.nv.doe.gov/news&pubs/photos&films/atm.htm

  8. Terms and Definitions • Fission: a large atom of one element is split to produce two different smaller elements • Fusion: two small atoms combine to form a larger atom of a different element • Isotope: different (mass number) forms of the same element

  9. Two Forms of Uranium • 238U = 92 protons + 146 neutrons • 235U = 92 protons + 143 neutrons

  10. Fission, Fusion, or Both? • Energy is released • Begins with 235U • Produces radioactive by-products • Produces free neutrons

  11. Fission, Fusion, or Both? • Splits a larger atom into smaller atoms • Fuses smaller atoms in one larger atom • Begins with 2H and 3H • Produces helium

  12. Terms and Definitions • Fuel rods: rods full of 235U pellets • Moderator: fluid (water) coolant that slows down neutrons • Control rods: moderate rate of the chain reaction by absorbing neutrons

  13. A Nuclear Reactor

  14. A Nuclear Reactor Is Designed to • Sustain a continuous chain reaction • Prevent amplification into a nuclear explosion • Consist of an array of fuel and control rods • Make some material intensely hot

  15. A Nuclear Power Plant

  16. A Nuclear Power Plant Designed to • Use steam to drive turbogenerators • Convert steam into electricity • Produce superheated water in a reactor vessel • Prevent meltdown

  17. Comparing Nuclear Power with Coal Power

  18. Comparing Nuclear Power with Coal Power • Requires 3.5 million tons of raw fuel • Requires 30 tons of raw material • Emits over 7 million tons of CO2 into the atmosphere • Emits no CO2 into the atmosphere

  19. Comparing Nuclear Power with Coal Power • Emits over 300 thousand tons of SO2 into the atmosphere • Emits no acid-forming pollutants • Produces about 100 thousand tons of ash • Produces 250 tons of radioactive waste • Possible meltdown

  20. Comparing Nuclear Power with Coal Power • Produces 250 tons of radioactive waste • Possible meltdown

  21. Terms and Definitions • Radioisotopes: unstable isotopes of the elements resulting from the fission process

  22. Terms and Definitions • Radioactive emissions: subatomic particles (neutrons) and high-energy radiation (alpha, beta, and gamma rays) • Radioactive wastes: materials that become radioactive by absorbing neutrons from the fission process

  23. The Hazards and Costs of Nuclear Power Facilities • Radioactive emissions • Radioactive wastes • Disposal of radioactive wastes • Nuclear power accidents • Safety and nuclear power • Economic problems with nuclear power

  24. Radioactive Emissions and Wastes

  25. Radioactive Decay Half life = the time for half the amount of a radioactive isotope to decay

  26. Half-life • Molybdenum-99 (half-life = 2.8 days) • Xenon-133 (half-life = 5.3 days) • Krypton-85 (half-life = 10.7 years) • Cesium-137 (half-life = 30.0 years) • Plutonium-239 (half-life = 24,000 years)

  27. Disposal of Radioactive Wastes (200 Thousand Tons) • Finding long-term containment sites • Transport of highly toxic radioactive wastes across the United States • The lack of any resolution to the radioactive waste problem • Environmental racism • Cost ($60 billion to 1.5 trillion)

  28. Disposal of Radioactive Wastes • To be safe, plutonium-239 would require 240,000 years (10 half-lives) of containment! • Discuss the implications of this in terms of disposal of radioactive wastes. • Yucca Mountain in southwestern Nevada = the nation’s nuclear waste repository

  29. Nuclear Power Accidents • Three-mile Island • 1979 • Harrisburg, PA • Loss of coolant in reactor vessel • Damage so bad, reactor shut down permanently • Unknown amount of radioactive waste released into atmosphere

  30. How Chernobyl Blew Up • Loss of water coolant perhaps triggered the accident. When the water-circulation system failed, the temperature in the reactor core increased to over 5,000 oF, causing the uranium fuel to begin melting and producing steam that reacted with the zirconium alloy cladding of the fuel rods to produce hydrogen gas.

  31. How Chernobyl Blew Up • A second reaction between steam and graphite produced free hydrogen and carbon oxides. When this gas combined with oxygen, a blast blew off the top of the building, igniting the graphite. The burning graphite threw a dense cloud of radioactive fission products into the air.

  32. Consequences of Radiation Exposure • Block cell division • Damage biological tissues and DNA • Death • Cancer • Birth defects

  33. Safety and Nuclear Power • Passive rather than active safety features • New generations of reactors (ALWRs, see Fig. 13-15) • Terrorism and nuclear power: dirty bombs or outright attacks

  34. Economic Problems with Nuclear Power • Energy demand estimates were unrealistic. • Costs increases (5x) to comply with new safety standards. • Withdrawal of government subsidies to nuclear industry. • Public protests delayed construction. • Any accident financially ruins the utility.

  35. More Advanced Reactors • Breeder reactors • Fusion reactors

  36. Breeder, Fusion, or Both • Creates more fuel than it consumes • Raw material is 238U • Splits atoms

  37. Breeder, Fusion, or Both • Fuses atoms • Releases energy • Raw material is deuterium and tritium • Source of unprecedented thermal pollution

  38. The Future of Nuclear Power: Opposition • General distrust of technology • Skepticism of management • Doubt overall safety claims about nuclear power plants • Nuclear power plants are prime targets for terrorist attacks • Nuclear waste disposal problems

  39. The Future of Nuclear Power: Rebirth? • Need to address public concerns listed in the opposition section. • Waste dilemma must be resolved. • Strong political leadership capable of analyzing the full spectrum of problems associated with the future of nuclear power is needed.

  40. End of Chapter 13

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