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Nuclear Power. Physics 1303 4/7/03. Outline . The Nucleus Radioactivity Fission Fusion Nuclear Weapons Nuclear Power. Nucleus. Composed of protons and neutrons 239 Pu 94 or Pu – 239 94 protons 145 neutrons Isotope of Plutonium . Radioactivity. Some isotopes are unstable
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Nuclear Power Physics 1303 4/7/03
Outline • The Nucleus • Radioactivity • Fission • Fusion • Nuclear Weapons • Nuclear Power
Nucleus • Composed of protons and neutrons • 239Pu94 or Pu – 239 • 94 protons • 145 neutrons • Isotope of Plutonium
Radioactivity • Some isotopes are unstable • Spontaneously Decay • Decaying isotopes emit particles
Radon is a health hazard • Product of the decay of naturally occurring uranium • Affects indoor air quality • 2nd leading cause of lung cancer • Regional issue
Half-life • Pu-239 decays to U-235 with the emission of an alpha particle: • The time for half of the Pu-239 nuclei to decay is called the half-life. • 24,000 years is half-life for Pu-239 decay
Aside: Pathetic Joke • Did you hear about the socially sophisticated physicist?. • He was the half-life of the party.
Fission • By bombarding a nucleus with neutrons, a stable isotope can be induced to fission or split. • U-235 is an example of a fissionable material. • The release of neutrons in this reaction means that we can set up a chain reaction
Fission Releases Energy • When the fission is controlled, as in a nuclear reactor, it can be a practical source of power. • When the fission is uncontrolled it can be the basis for weapons of mass destruction.
Fusion • Two light nuclei combine to form a heavier nucleus. • The fusion of deuterium (a hydrogen isotope) with tritium (another hydrogen isotope) to form a helium nucleus can release a great deal of energy.
Fusion Power • Using a fission bomb as a trigger, a hydrogen bomb, or a H-bomb uses fusion to create a WMD. • Solar energy originates as fusion energy in the sun’s interior. • Fusion power is an active area of research.
Nuclear Weapons • First nuclear weapon tested at Trinity site in 1945 used Pu-239. • The fuel for the Hiroshima and Nagasaki bombs were U-235 and Pu-239, respectively. • First H-bomb test in 1952
Country Strategic Tactical Total United States 7,300 3,200-4,700 10,500-12,000 Russia 6,000 7,000-15,000 13,000-20,000 China 290 120 400-410 France 400 80 400-482 United Kingdom 100 100 200 India - 85-90 85-90 Israel - 100-300 100-300 Pakistan - 15-25 15-25 Global Total - - 24,700-33,507 Nuclear Weapons
Nuclear Reactors:Boiling Water Reactor (BWR) • Similar to coal plant: boils water, makes steam, steam drives turbine, turbine turns electrical generator • Fissioning of U-235 is the fuel.
BWR Components • Containment building prevents release of radiation • Water is needed as coolant and to prevent meltdown.
Nuclear Reactor is a Heat Engine • Efficiency is similar to a coal burning plant, about 33% • So, 2/3 of the released energy is waste heat.
Uranium Fuel • Only 0.7% of natural U is U-235. • U-238 is not fissionable. • U must be enriched to 2.8% U-235.
Uranium Fuel Supply • Worldwide U-235 resource does not offer a long-term energy solution. • Breeder reactor consuming U-235 can convert U-238 into Pu-239.
Plutonium Economy • Breeder reactors would greatly increase the availability of weapons-grade Plutonium.
Nuclear Power in the US • 104 nuclear plants • Produce 20% US Electricity • No new plants since 1973 • Why?
Nuclear Accidents • 1979 Three Mile Island partially core melt • 1986 Chernobyl explosion and fire, release of radiation
Waste Disposal • WIPP near Carlsbad, NM. Stores hi-level waste associated with nuclear weapons • Yucca Mountain, Nevada. High-level waste from commercial reactors.
Will there be a nuclear renewal? • Economics do not look good. Very capital intensive. • Fear of terrorism • Anti-nuclear groups • Waste disposal