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Unit 7 – Chapter 9, Part 2

Unit 7 – Chapter 9, Part 2. Nuclear Energy David Rude. Non-Renewable Energy Sources. Diablo Canyon Nuclear Power Plant. Outline. 9.5 Nuclear Power 9.6 The Nature of Nuclear Energy 9.7 Nuclear Chain Reaction 9.8 Nuclear Fission Reactors. Outline. 9.9 The Nuclear Fuel Cycle

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Unit 7 – Chapter 9, Part 2

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  1. Unit 7 – Chapter 9, Part 2 Nuclear Energy David Rude

  2. Non-Renewable Energy Sources Diablo Canyon Nuclear Power Plant

  3. Outline • 9.5 Nuclear Power • 9.6 The Nature of Nuclear Energy • 9.7 Nuclear Chain Reaction • 9.8 Nuclear Fission Reactors

  4. Outline • 9.9 The Nuclear Fuel Cycle • 9.10 Issues Related to the Use of Nuclear Fuels

  5. 9.5 Nuclear Power • Nuclear power is fueled by uranium • Obtained from mining • Non-renewable. • Word energy sources in order of importance: • Oil • Coal • Natural gas • Hydroelectric • Nuclear • Fifth most important

  6. 9.5 Nuclear Power • Main reasons for opposing nuclear power: • Threat to world peace • This group opposes all things nuclear • Environmental concerns due to potential nuclear contamination • Problem of waste disposal

  7. 9.5 Nuclear Power • Two reasons for renewed interest • The threat of climate change • Does not produce carbon dioxide • Many now see it as a continuing part of the energy equation • Economics • Increased cost of oil and natural gas makes nuclear more attractive

  8. 9.5 Nuclear Power • World’s energy production: • 14% of world-wide electrical output • 5½% of all power consumed

  9. 9.5 Nuclear Power • As of 2011 • 440 nuclear power reactors in operation • 61 under construction in 13 countries • 169 nuclear power plants currently planned • Most in Asian countries • Breakdown: • 85 in China, India, Japan and South Korea • 14 in Russia • 7 in US

  10. 9.5 Nuclear Power • 19 Countries get 20% or more of electricity from nukes • US – 20% • Japan – 30% • France – 75% • Original operation licenses were for 40 years • Most are being extended to 60 years • Delays decommissioning for 20 years • No new plants needed to replace lost capacity

  11. 9.6 The Nature of Nuclear Energy • Atoms • Basic building blocks of matter • Element • Cannot be divided into any other type of matter • Oxygen, carbon, hydrogen, iron, and aluminum • 90 naturally occurring kinds • 25 types made by scientists

  12. 9.6 The Nature of Nuclear Energy • Compound • Matter made up of two or more types of atoms • Examples • Water, steel, oil, plastic

  13. 9.6 The Nature of Nuclear Energy • Three basic parts • Protons – positive charge • Neutrons – no charge • Electrons – negative charge • Heald together by • Nuclear force

  14. The Nature of Nuclear Energy • Radioactive • Nuclei of certain atoms are unstable and spontaneously decompose (break apart) • Neutrons • Electrons • Protons • Other larger particles • Great deal of energy

  15. When atoms decay and release particles • Become a different type of atom • Example: U-238

  16. The Nature of Nuclear Energy • Radioactive Half-Life • Time it takes for half the radioactive material to spontaneously decompose • Isotope: • An atom with the same number of protons, but different numbers of neutrons • Isotopes are different forms of a single element.

  17. The Nature of Nuclear Energy • Carbon • C12 – 6 Protons, 6 Neutrons • Stable • 98.8% • C13 – 6 Protons, 7 Neutrons • Stable • 1.1% • C14 – 6 Protons, 8 Neutrons • Unstable – 5,730 yearhalf-life C14 Half Life

  18. The Nature of Nuclear Energy • Iodine • 37 known isotopes • I-127 is only stable isotope • 53 Protons • 74 Neutrons • Iodine-131 • 53 Protons • 78 Neutrons • Used in Medicine • 8 day half-life • Emits beta radiation (electrons) Dental X-Ray = 2-3 millicuries

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  21. The Nature of Nuclear Energy • Radiation • Energy released from the nucleus during nuclear disintegration • Three basic types of radiation • Alpha • Two neutrons and two protons • Stopped by sheet of paper • Beta radiation • Electrons • Stopped by layer of clothing, glass or aluminum

  22. The Nature of Nuclear Energy • Gamma radiation • Electromagnetic radiation

  23. The Nature of Nuclear Energy • Nuclear fission • Neutrons hit and split the nuclei of certain other atoms • Fissionable • Atoms that can split easily • Nuclear chain reaction • Splitting nuclei release neutrons • These strike more nuclei releasing more neutrons • Cascading effect

  24. The Nature of Nuclear Energy Nuclear fission chain reaction

  25. The Nature of Nuclear Energy • Atoms suitable nuclear chain reaction • Two most common • Uranium-235 • Plutonium-239. • Must be a certain quantity of nuclear fuel (critical mass)

  26. 9.8 Nuclear Fission Reactors • Nuclear reactor • A device that permits a controlled fission chain reaction • U-235 is fuel • Fissionable: element whose nucleus will split apart

  27. The Nature of Nuclear Energy Nuclear fission chain reaction

  28. Nuclear Fission Reactors • Control rods • Made of a non-fissionable material (boron, graphite) • Absorb neutrons to control rate of fission • Rate slows when inserted • Rate increases when withdrawn • Moderator • Substance that absorbs energy • Slows neutrons • Enables them to split the nuclei of other atoms more effectively

  29. Nuclear Fission Reactors • Core coolant • Material used to transfer heat away from the core • Prevents overheating and melting of reactor casing • Usually water

  30. Nuclear Fission Reactors • A nuclear reactor serves the same function as a fossil-fuel boiler • Produces heat • Heat converts water to steam • Steam turns a turbine • Turbine spins a giant coil of wire between to large magnets

  31. Nuclear Fission Reactors • Three most common types of reactors • 20% Boiling-Water • 60% Pressurized-Water • 10% Heavy-Water • Uses Deuterium • Hydrogen stable isotope (1 proton, 1 neutron) • Boils at higher temperature • Gas-Cooled Reactors are not popular • No new plants being constructed

  32. Nuclear Fission Reactors • Boiling-water reactor • Steam forms in reactor and turns turbine • Disadvantages • Steam must be treated to remove any radiation • Some radioactive material is left in the steam • Generating building must be shielded

  33. Nuclear Fission Reactors Boiling water reactor

  34. Nuclear Fission Reactors • Pressurized water reactor • Water is pressurized so it doesn’t form steam • Secondary loop transfers the heat from the pressurized water in the reactor to a steam generator. • Advantages/Disadvantages • Less waste radiation • Increased costs of construction • Easier maintenance due to radiation being contained

  35. Nuclear Fission Reactors Pressurized-water reactor

  36. Nuclear Fission Reactors • Heavy-water reactor • Basically same as Pressurized Water Reactors • Uses water with deuterium instead of regular hydrogen • Normal Hydrogen: one Proton and Electron – no neutron • Deuterium: one proton, neutron and electron • A stable isotope of hydrogen • Not radioactive

  37. Nuclear Fission Reactors • Advantages • Heavy water is a better moderator than regular water • Moderator slows free neutrons • more efficient at splitting nuclei • Cheaper to run since it can use regular uranium • Uses naturally occurring U-238 instead of enriched U-235

  38. 9.8 Nuclear Fission Reactors • Breeder reactors produce nuclear fuel as they produce electricity. • Liquid sodium efficiently moves heat away from the reactor core. • Hence they are called Liquid Metal Fast Breeder Reactors. • A fast moving neutron is absorbed by Uranium-238 and produces Plutonium-239 • P 239 is fissionable fuel. • Most breeder reactors are considered experimental. • Because P239 can be used in nuclear weapons, they are politically sensitive.

  39. Investigating Nuclear Alternatives • Breeder reactors • Produce nuclear fuel as they produce electricity • Plutonium • Requires fast moving neutrons • Cannot use water as a moderator • Lots of heat is generated • Uses liquid metal as core coolant • Usually sodium • Also called Liquid Metal Fast Breeder Reactors • Most considered experimental

  40. Investigating Nuclear Alternatives Formation of Pu-239 in a breeder reactor

  41. Investigating Nuclear Alternatives • Problems • Produce Plutonium-239 • Very hazardous to humans • Can be used in nuclear weapons • Very dangerous to operate • If liquid sodium boils it can damage reactor and lead to a nuclear accident. • Liquid sodium must be at 620oC so it requires very specialized equipment. • When shut down sodium becomes a solid

  42. Investigating Nuclear Alternatives • Can be difficult to operate because the reaction occurs so rapidly • Most have been shut down • Currently • Only operating in Russia, China, & Japan • Russia and India plan to build new ones

  43. Investigating Nuclear Alternatives • Nuclear fusion • Two lightweight atomic nuclei combine to form a heavier nucleus • Releases large amount of energy • Fusion occurs in stars like our sun. • Currently not possible provide a reliable source of energy with fusion • Governments provide little funding for fusion research

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