Nuclear Reactions: AN INTRODUCTION TO FISSION & FUSION

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Nuclear Reactions
AN INTRODUCTION TO FISSION FUSION
Farley Visitors Center
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Introduction

• Nuclear reactions deal with interactions between
  the nuclei of atoms
• The focus of this presentation are the processes
  of nuclear fission and nuclear fusion
• Both fission and fusion processes deal with
  matter and energy

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Matter and Energy

• Previous studies have taught us that matter and
  energy cannot be created nor destroyed
• We now need to understand that Matter and Energy
  are two forms of the same thing

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E mc2

• Matter can be changed into Energy
• Einsteins formula above tells us how the change
  occurs
• In the equation above
• E Energy
• m Mass
• c Speed of Light (Universal Constant)

Mass
Energy
Light Speed
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E mc2

• The equation may be read as follows
• Energy (E) is equal to Mass (m) multiplied by
  the Speed of Light (c) squared
• This tells us that a small amount of mass can be
  converted into a very large amount of energy
  because the speed of light (c) is an extremely
  large number

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Fission

• Fission may be defined as the process of
  splitting an atomic nucleus into fission
  fragments
• The fission fragments are generally in the form
  of smaller atomic nuclei and neutrons
• Large amounts of energy are produced by the
  fission process

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Fission

• Fissile nuclei are generally heavy atoms with
  large numbers of nucleons
• The nuclei of such heavy atoms are struck by
  neutrons initiating the fission process
• Fission occurs due to electrostatic repulsion
  created by large numbers of protons within the
  nuclei of heavy atoms

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Fission

• A classic example of a fission reaction is that
  of U-235
• U-235 1 Neutron
• 2 Neutrons Kr-92 Ba-142 Energy
• In this example, a stray neutron strikes an atom
  of U-235. It absorbs the neutron and becomes an
  unstable atom of U-236. It then undergoes
  fission. Notice that more neutrons are released
  in the reaction. These neutrons can strike other
  U-235 atoms to initiate their fission.

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Fission

• The fission process is an a natural one as a
  French researcher found a natural uranium reactor
  in Gabon, West Africa it has been estimated to
  be over 2 billion years old
• Fission produces large amounts of heat energy and
  it is this heat that is captured by nuclear power
  plants to produce electricity

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Fusion

• Fusion is a nuclear reaction whereby two light
  atomic nuclei fuse or combine to form a single
  larger, heavier nucleus
• The fusion process generates tremendous amounts
  of energy refer back to Einsteins equation
• For fusion to occur, a large amount of energy is
  needed to overcome the electrical charges of the
  nuclei and fuse them together

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Fusion

• Fusion reactions do not occur naturally on our
  planet but are the principal type of reaction
  found in stars
• The large masses, densities, and high
  temperatures of stars provide the initial
  energies needed to fuel fusion reactions
• The sun fuses hydrogen atoms to produce helium,
  subatomic particles, and vast amounts of energy

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Review

• Mass and Energy are two forms of the same thing
  neither can be created nor destroyed but mass can
  be converted into energy (E mc2)
• Fission is a nuclear reaction in which a heavy
  atomic nucleus is split into lighter atomic
  nuclei
• Fusion is a nuclear reaction in which 2 light
  atomic nuclei are combined into a single, heavier
  atomic nucleus

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Quiz

• Which nuclear process produces large amounts of
  energy?
• A. Fission
• B. Fusion
• C. Both fission fusion
• D. Neither fission nor fusion

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Quiz

• Fission is the process that _________ atomic
  nuclei.
• A. Combines
• B. Burns up
• C. Stores
• D. Splits

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Quiz

• Mass may be converted into energy.
• A. True
• B. False

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Quiz

• The fission process requires heavy atomic
  nuclei.
• A. True
• B. False

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Quiz

• Name a nuclear reaction that occurs within the
  sun

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Quiz

• Fission is a natural process that occurs on the
  planet Earth.
• A. True
• B. False

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Quiz

• Explain this equation
• E mc2