Nuclear Energy

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Nuclear Energy
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Why nuclear?

• Power shortages
• Rising prices
• Emissions of gases
• Running out of oil
• Good option??

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Brief History of Nuclear Power In The USA

• US Utility Companies Begin Development in late
  1950s
• Support From Government
• Atomic Energy Commission
• Subsidies
• Government Assumes Liability
• Slow/No Growth in US in Last 30 Years fear
  based
• 103 Plants in US Generate About 21 of
  Electricity
• This May Change. (decreasing use)
• Worldwide, 441 plants, 32 under construction.
  17 of worlds energy

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Nuclear Power Plants in the United States
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Some Definitions.

• Fission a large atom of one element is split to
  produce two different smaller elements (uranium
  -gt by products, neutrons and energy)
• Fusion two small atoms combine to form a larger
  atom of a different element (Hydrogens -gt Helium
  energy and neutron)
• Isotope different (mass number) forms of the
  same element (uranium 235, 238 differ in
  neutrons, same proton and electron )

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How Fission Works
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Nuclear Fuel

• Of the two Uranium isotopes, U-235 readily
  undergoes fission
• Fuel for reactor
• Enriched Uranium (separating isotopes to choose
  for U-235
• 4 enrichment (4 U-235, 96 U-238 to prevent
  amplification of explosion)
• Highly enriched spontaneous fission

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The Light Water Nuclear Reactor

• Fuel rods rods full of 235U pellets
• Moderator fluid (water) coolant that slows down
  neutrons so neutrons are traveling at the right
  speed to trigger another fission rxn. Get hot
  during reactions.
• Control rods (boron or cadmium) moderate rate of
  the chain reaction by absorbing neutrons

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In the Core
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Comparing Nuclear vs. Coal Power Plants
Coal Nuclear
Ample Supply Ample Uranium Supply
Low Net Energy Yield High Net Energy Yield
Very High Air Pollution Low Air Pollution
High CO2 Emissions Low CO2 Emissions
High Land Disruption Low Land Disruption
High Land Use Moderate/Low Land Use
Low Cost High Cost

• Base Load Power best comparison is nuclear vs.
  coal

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Comparing Coal and Nuclear Power
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Concerns With Nuclear Power

• Radioactive emissions
• Radioactive wastes
• Disposal of radioactive wastes
• Nuclear power accidents
• Safety and nuclear power
• Economic problems with nuclear power

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Some Definitions

• Radioisotopes unstable isotopes of the elements
  resulting from the fission process
• 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

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Radiation is Everywhere Nuclear Power is Not
the Only Source (or even a Major Source)

• Television
• Household Radon
• Airplane Flights
• Emissions From Coal Power Plants
• Medical X-Rays
• Radon

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Radioactive Decay
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What to do with the waste?

• It Depends.
• Waste could be spent fuel rods
• Waste could be dismantled reactor parts
• Two Stages
• Short-term containment (short-lived isotopes
  decay to a point where they are easier to deal
  with)
• Long-term containment (10000 year minimum!)

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What to do with the waste?

• Siting (NIMBY)
• Transport
• Cost (60 billion to 1.5 trillion)
• Yucca Mountain in southwestern Nevada the
  nations nuclear waste repository (operational in
  2010? Or 2015 Or NEVER)

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Nuclear Accidents Three Mile Island

• United States Three-mile Island
• 1979
• Harrisburg, PA
• Loss of coolant in reactor vessel
• Damage so bad, reactor shut down permanently
• Unknown amount of radiation released into
  atmosphere

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Nuclear Accidents Chernobyl

• 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.
• 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.

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Kidd of Speed
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