Nuclear Energy

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Nuclear Energy

• Chapter 16

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Atoms and Radioactivity

• All common forms of matter are composed of atoms.
• All atoms are composed of
• 1) Protons (found in the nucleus)
• 2) Neutrons (found in the nucleus)
• 3) Electrons (found orbiting the
  nucleus)

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Isotopes

• Elements that have the same number of protons and
  electrons but
• Different numbers of neutrons

1 proton and 1 electron ? 1
proton and 1 electron and 1 neutron
? 1 proton and 1 electron and 2 neutrons
?
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16.1 Atoms and Radioactivity

• Radioactive - Nuclei of certain atoms are
  unstable and spontaneously decompose and release
  particles and energy.
• Radioactive Half-Life - Time it takes for half
  the radioactive material to spontaneously
  decompose.

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What is released by radiation?

• 3 Things
• Alpha Particles
• Beta Particles
• Gamma Rays

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16.2 Reactions and Reactors

• Nuclear Fission A reactions in which the
  nucleus of a large atom is split into smaller
  nuclei

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• Nuclear Chain Reaction - Splitting nuclei release
  neutrons, which themselves strike more nuclei, in
  turn releasing even more neutrons.

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The Nature of Nuclear Energy

• Only certain kinds of atoms are suitable for
  development of a nuclear chain reaction.
• The two most common are uranium-235 and
  Plutonium-239.
• Requires certain quantity of nuclear fuel
  (critical mass).

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Nuclear Fission Reactors

• Nuclear Reactor - Device that permits a
  controlled fission chain reaction.
• Nucleus of U-235 atom struck by slowly moving
  neutron from another atom.
• Nucleus split into smaller particles.
• More neutrons released.
• Strike more atoms.

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Nuclear Fission Reactors

• Control Rods - Made of a non-fissionable material
  (boron, graphite) that are lowered into reactor
  to absorb neutrons.
• Withdrawn to increase rate of fission.

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Workings of A Nuclear Reactor

• Nuclear reactor serves same function as
  fossil-fuel boiler produces heat - converts
  water to steam - turns a turbine - generating
  electricity.
• Breeder Reactors - Nuclear fission reactor that
  forms a new supply of radioactive isotopes during
  operation. (i.e., U238 turns into Pu239)

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Boiling Water Reactor
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Nuclear Power Plants in North America
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16.3 Radioactive Waste

• High Level Radioactive Waste
• At this time, no country has a permanent storage
  solution for the disposal of high-level
  radioactive waste.
• Politics of disposal are as crucial as disposal
  method.
• Most experts feel the best solution is to bury
  waste in a stable geologic formation.

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Low-Level Radioactive Waste

• Includes cooling water from nuclear reactors,
  material from decommissioned reactors, protective
  clothing, and like materials.
• Prior to 1970, U.S. alone placed 90,000 barrels
  of low-level radioactive waste on the ocean
  floor.
• Moratorium in 1970, banned in 1983.

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Low - Level Waste

• Currently, U.S. produces about 800,000 cubic
  meters of low-level radioactive waste annually.
• Presently buried in various scattered disposal
  sites.
• Political limbo.

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Low-Level Radioactive Waste Sites
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Reactor Safety

• Three Mile Island - Pennsylvania
• March 28, 1979 - Partial Core Melt-Down.
• Pump and valve malfunction.
• Operator error compounded problem.
• Crippled reactor was de-fueled in 1990 at a cost
  of about 1 billion.
• Placed in monitored storage until its companion
  reactor reaches the end of its useful life.

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Reactor Safety

• Chernobyl - Ukraine
• April 26, 1986
• Experiments being conducted on reactor.
• Multiple serious safety violations.
• Reactor Explodes.
• 31 deaths.
• 116,000 people evacuated.
• 24,000 evacuees received high doses of radiation.
• Increased thyroid cancer in children.

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