FUSION AND FISSION

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FUSION AND FISSION
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THE SUN
Every second, the sun converts 500 million metric
tons of hydrogen to helium. Due to the process of
fusion, 5 million metric tons of excess material
is converted into energy in each second. This
means that every year, 157,680,000,000,000 metric
tons are converted into energy.
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(No Transcript)
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Nuclear Fusion

• Nuclear fusion is the process by which multiple
  nuclei join together to form a heavier nucleus.
• It is accompanied by the release or absorption of
  energy depending on the masses of the nuclei
  involved..

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FUSION
NEUTRON
DEUTERIUM
HELIUM
TRITIUM
http//fusioned.gat.com
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Nuclear Fusion

• Iron and nickel nuclei have the largest binding
  energies per nucleon of all nuclei and therefore
  are the most stable.

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Nuclear Fusion

• The fusion of two nuclei lighter than iron or
  nickel generally releases energy.
• The fusion of nuclei heavier than them absorbs
  energy.

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Complete the Reaction
1H element atomic number
(protons)
4Be
1H
2He
6C
2He
1H
1H
6C
2He
4Be
8O
2He
2He
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Energy needed for Fusion

• The thermal activity of a gas is described by its
  temperature measurement which is really an
  indication of its velocity/energy.
• Thermal energy is represented by the height that
  the upper magnet.
• The upper ring has a potential energy given by PE
  mgh at its drop point which is converted into
  kinetic energy (KE 1/2 mv2)
• As the magnet falls towards the lower magnet. The
  two magnets click lightly when the kinetic energy
  is just greater than the magnetic energy that
  holds them apart.
• Since Kinetic Energy Potential Energy (ignoring
  frictional components), the gravitational pull
  and mass of the upper magnet are constant, then
  the height needed to overcome the magnetic
  repelling force is proportional to that magnetic
  repelling force.

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Energy needed for Fusion
PE mg x h2-h1 PE KE Fxh1 Fforce of
repulsion FPE/h1
Upper Drop Position Ring Magnets Float
Position Lower Magnet Wood Block
h2
h1
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Fusion Changes Mass to EnergyEmc2
.993 kg Helium
He
H
1kg Hydrogen
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Cookie Fusion

• Procedure
• Cut 2 squares of wax paper 10 cm on a side
• Cut 5 cm wide slice of cookie dough (atom)
• Find the mass of the atom and record on the table
• Place the atom one cm away from the edge of a wax
  paper square
• Repeat step 2 thru 4 for a second atom
• Place the atoms about 2 cm from each other
• Place both atoms on a plate and microwave for 1
  minute
• Remove the new element and let cool for 2
  minutes
• Find the mass of the new element
• Complete the table

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Cookie Fusion
Mass Before Cooking Mass After Cooking
Atom 1
Atom 2
Total
Difference
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Learning Check

• What process creates energy in the Sun?
• Fusion of hydrogen into helium in the Suns
  core generates the Suns energy.
• How long ago did fusion generate the energy we
  now receive as sunlight?
• Fusion created the energy we receive today
  about a million years ago. This is the time it
  takes for photons and then convection to
  transport energy through the solar interior to
  the photosphere. Once sunlight emerges from the
  photosphere, it takes only about 8 minutes to
  reach Earth.

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Learning Check

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NUCLEAR FISSION

• A reaction in which an atomic nucleus of a
  radioactive element splits by bombardment from an
  external source, with simultaneous release of
  large amounts of energy, used for electric power
  generation

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Nuclear Fission
Neutron induced in U235
Fission is Exothermic The sum of the masses of
the resulting nuclei is less than the original
mass (about 0.1 less) The missing
mass is converted to energy according to Emc2
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Neutrons may

• 1 - Cause another fission by colliding with a
  U235 nucleus
• 2 - Be absorbed in other material
• 3 - Lost in the system
• If sufficient neutrons are present, we may
  achieve a chain reaction

• Creates two smaller nuclides and free neutrons
• The free neutrons potentially collide with
  nearby U235 nuclei
• May cause the nuclide to split as well

Each split (fission) is accompanied by a large
quantity of E-N-E-R-G-Y
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U.S. Electrical Power Production by Source
Source EIA
(2004)
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Nuclear Fuel Costs

• Nuclear Fuel Costs Include
• Uranium
• Enrichment
• Manufacturing
• Waste Disposal
• Total Nuclear Fuel Cost is Only About 0.5 cents
  per kilowatt-hour
• Uranium accounts for only about 20 of this cost
  or 0.1 cents per kilowatt-hour
• Increasing Uranium Cost has Minimal Impact

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Review
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Draw a Double Bubble Map of Fusion and Fission
fission
fusion
Differences Similarities
Differences