Nuclear Power Structure, Uses

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Nuclear PowerStructure, Uses Future

• By Jack Percival

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The Process
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Inside the Fission Reactor

• U-235 is usually main reactant in the core
• U-238 makes up majority of mass, but very little
  of energy directly (about 95-98 of mass is
  U-238)
• U-238 can absorb a neutron and through series of
  ß- decays, will become Pu-238
• Pu-238 is a fissile element and can also be used
  in core
• Products of Fission are always radioactive
• They contribute some extra energy to the core
  when they decay
• Also represent the main problem with waste

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The Fission Process
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Internal Structure
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Overall Structure
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In detail Moderators

• Reactions are made possible by moderators
• They absorb the Kinetic Energy from the neutrons
  through elastic collisions
• This means they are slow enough to cause more
  fission
• Key ideas for a good moderator
• High Density Chemically Stable
• Low Atomic Weight High Boiling Point
• Low Neutron Absorption Inexpensive
• For these reasons there are 3 typical moderators
• Graphite, Light Water, and Heavy Water
• Light water is most common because it fits all of
  the properties the best while being the cheapest

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In detail Control Rods

• Have absorption range similar to the output of
  core
• They can been move up and down in order to
  control the absorption
• This takes away neutrons from being to react with
  uranium in core
• This slows down fission rate, or can completely
  shut down the core in an emergency
• As the neutrons are absorbed they cannot go on to
  react- this is the control mechanism for the
  reactor

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In detail Steam and Water

• Reactions heat the water which is being pumped
  into the reactor
• This is then passed close to water not under
  pressure, which turns into steam
• This prevents all the water becoming radioactive
• The coolant water is usually from the nearby
  water sources, sometimes the sea
• This steam drives the turbine
• The turbine is used to produce electricity

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In detail Containment Safety

• Core will automatically shut itself down once a
  temperature range is breached
• Control Rods are inserted to start
• Moderator is then poisoned by injecting boric
  acid
• Heat exchangers are used to prevent any
  radioactive material from escaping
• Shell around core strong enough to withstand a
  full airline collision and even a light missile
  attack
• Not even severe earthquakes have been able to
  crack these shells

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Advantages Disadvantages
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Nuclear Power Advantages

• Nuclear power costs comparatively little in
  ongoing costs
• Does not produce smoke or carbon dioxide, only
  stream, so it does not contribute to the
  greenhouse effect.
• Produces huge amounts of energy from small
  amounts of fuel.
• Produces small amounts of waste.
• Reliable

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Nuclear Power Disadvantages

• Although not much waste is produced, it is very,
  very dangerous. It must be sealed up and buried
  for many years to allow the radioactivity to
  reduce to a safe level
• Nuclear power is reliable, but a lot of money has
  to be spent on safety - if it does go wrong, a
  nuclear accident can be a major disaster.
• Very expensive set up costs and lengthy process
• Seen as a possible terrorist target
• Has a NIMBY effect
• Very expensive to decommission
• Long payback time
• Not harnessing the true energy from the process
  relatively inefficient
• Non-renewable fuel supplies

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Nuclear Fusion The Future
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Nuclear Fusion The Basics

• Stellar nuclear fusion 4H ?He
• High Energy production
• Nuclear fusion power uses Deuterium and Tritium
  isotopes of Hydrogen

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Nuclear Fusion Today

• Whilst a reactor is being built in France, high
  scale power production is still a long way off
• Fusion requires conditions of a very high
  temperature and pressure, similar to those found
  in the core of the sun
• These situations are near impossible to produce
  on earth, therefore scientists are looking for a
  solution Cold fusion
• Whilst this has been done, it has only been
  produced in small amounts, not enough for large
  scale power production

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Thank You For Listening