Nuclear Power

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Nuclear Power
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How does it work?

• Uranium-235 is often use to fuel nuclear power
  plants. It has an interesting property that makes
  it useful for this because it can undergo induced
  fission.

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Nuclear Fission
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Chain Reaction

• When the neutrons ejected from each fission hit
  another nearby nucleus, that one splits and
  releases more neutrons, etc. This sets up a
  chain reaction that keeps going and going
  until..

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Control Rods are put into action

• These are made of a material that absorbs
  neutrons and are lowered when the reaction needs
  to be slowed down or stopped.

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How is the electricity created?

• The uranium bundle generates the heat which turns
  the water into steam. This drives the turbine,
  which spins a generator to produce power.

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Outside the Power Plant

• Once you get past the reactor itself, there is
  little difference between a nuclear power plant
  and a coal or oil powered one.

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The containment vessel

• Nuclear reactors are typically housed inside a
  concrete liner that acts as a radiation shield.
  That liner is housed inside a much larger steel
  containment vessel.

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Advantages of Nuclear Power

• Minimal air pollution
• Water pollution is low (some thermal pollution
  exists)
• Disruption of land is low to moderate
• (except the mining of uranium)
• One pound of U-235 can produce as much heat
  energy as 1,500 tons of coal!

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Disadvantages of Nuclear Power

• Highly toxic nuclear waste produced (some take
  thousands to millions of years to decay)
• Lifespan of facilities only 15-40 years
• Low net energy yield lots of energy required
  for mining uranium, processing ore or dismantling
  the plant
• Safety and malfunction issues

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So where does the plutonium come from anyway?

• Power plants create it when the uranium in their
  fuel fissions. Some of it ends up in the spent
  fuel as waste.
• Different isotopes of plutonium have different
  half-lives and different uses

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What is a breeder reactor?

• The Breeder Reactor was developed to use
  uranium-238. Here's how it works. A reactor is
  built with a core of fissionable plutonium,
  Pu-239. The plutonium-239 core is surrounded by a
  layer of uranium-238. As the plutonium-239
  undergoes spontaneous fission, it releases
  neutrons. These neutrons convert uranium-238 to
  plutonium-239. In other words, this reactor
  breeds fuel (Pu-239) as it operates. After all
  the uranium-238 has been changed to
  plutonium-239, the reactor is refueled.
• Plutonium production reactors operated by the
  U.S. government during the Cold War have all shut
  down.

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Nuclear Power Plants in the United States
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Who relies most on nuclear energy?
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Nuclear Catastrophes
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The INES scale

• The International and Radiological Event Scale is
  a worldwide tool for communicating to the public
  in a consistent way the safety significance of
  nuclear and radiological events.

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(No Transcript)
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Three Mile Island March 1979 Pennsylvania
INES Level 5
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What happened?

• A cooling malfunction caused a partial meltdown.
  Some radioactive water was released as well as
  radioactive gas. Many people were evacuated. The
  reactor did not explode as feared. No one was
  killed.
• A 25 year follow-up study in 2004 of 35,000
  residents within a 5 mile radius of TMI showed no
  significant increase in deaths from cancer.

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The China Syndrome

• This movie, released in March of 1979 depicted a
  very similar fictional incident to that which
  occurred on Three Mile Island about a week after
  it was released in theaters!!

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ChernobylApril 1986Ukraine
INES Level 7
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What happened?

• They were running a safety check. Regulations
  called for a minimum of 30 control rods. Only 6-8
  were used. This led to a series of events that
  caused rapid overheating and deformed the core.
  The extra control rods could not be inserted and
  the core melted, causing an explosion. Fires
  lasted for nine days.

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They made some BIG mistakes

• The emergency cooling system was turned off
• Past-due safety check was being run by
  inexperienced night crew
• Automatic safety devices that shut down the
  reactor were shut off
• Power output was lowered too much
• The plant had no secondary containment shell

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The effects

• It caused 30 immediate fatalities to workers and
  exposed approx. 500,000 people to dangerous
  levels of radiation.
• Air currents carried radioactive particles high
  into the atmosphere and allowed spreading.

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The result?

• These serious accidents put a definite halt on
  most plans to build new power plants in the
  United States and caused some that were already
  built to be shut down indefinitely. One such
  plant here on Long Island is..

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Shoreham Power Plant
Officially decommissioned in 1989
Customers are still paying for the 6 billion
dollar debt it has left.(3 surcharge on their
electric bills for 30 years)
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Fukushima Daiichi DisasterJapan March 11, 2011
Original INES Level 5/Upgraded to Level 7 in April
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A powerful tsunami generated by a magnitude 9.0
quake at sea slams into the power plant

• Damage is done to four of six reactors
• Cooling systems fail
• Fires are set off
• Hydrogen gas causes explosions
• Engineers use seawater in effort to cool down
  cores

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The Outcome?

• The world becomes skeptical again about the use
  of nuclear energy as old fears are revived .

• A handful of workers at the plant were
  accidentally killed while trying to control the
  overheating reactors.
• It is estimated that 1,000 people will die from
  cancers which result from radiation exposure.

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Electricity Production

• The World

• The United States