Nuclear Power

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Nuclear Power
Dennis Silverman, U C Irvine
In the US, 20 of our electricity is produced by
nuclear power. There are 103 US nuclear power
plants.
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California related reactors
Diablo Canyon, two reactors
San Onofre, two reactors
? of Palo Verde 1, 2, 3 in Arizona
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California Nuclear energy

• Each of the five reactors produces about 1,100
  million watts (megawatts) of electricity
• This is enough to power one million homes per
  reactor
• Each reactors production is equivalent to 15
  million barrels of oil or 3.5 million tons of
  coal a year.
• The total 5,500 reactor produced megawatts is out
  of a peak state electrical power of 30,000
  40,000 megawatts.

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Worldwide Nuclear Power Reactors

• There are 440 nuclear power reactors in 31
  countries.
• 30 more are under construction.
• They account for 16 of the worlds electricity.
• They produce a total of 351 gigawatts (billion
  watts) of electricity.

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World Nuclear Power Plants
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Nuclear Electricity Production by Countries and
Regions in Gigawatts (World Total 350 Gigawatts)
and percent of electricity
US 97 Trend declining
North America Region 109
France 63 Increasing
Germany 21 Being phased out
U. K. 12
Western Europe Region 126
Japan 44 Increasing
Asia Region 66 Increasing
Eastern Europe Region 11
Former Soviet U. Region 34
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How a Nuclear Reactor works

• 235U fissions by absorbing a neutron and
  producing 2 to 3 neutrons, which initiate on
  average one more fission to make a controlled
  chain reaction
• Normal water is used as a moderator to slow the
  neutrons since slow neutrons take longer to pass
  by a U nucleus and have more time to be absorbed
• The protons in the hydrogen in the water have the
  same mass as the neutron and stop them by a
  billiard ball effect
• The extra neutrons are taken up by protons to
  form deuterons
• 235U is enriched from its 0.7 in nature to about
  3 to produce the reaction, and is contained in
  rods in the water
• Boron control rods are inserted to absorb
  neutrons when it is time to shut down the reactor
• The hot water is boiled or sent through a heat
  exchanger to produce steam. The steam then
  powers turbines.

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Nucleons more tightly bound in Fission Product
Nuclei Gives 200 Mev Energy per Fission
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Nuclear Fission from Slow Neutrons and Water
Moderator
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Inside a Nuclear Reactor

• Steam outlet ?
• Fuel Rods ?
• Control Rods ?

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Energy Taken out by Steam Turbine
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Production of Plutonium (Pu) in Nuclear Reactors

• 239Pu is produced in nuclear reactors by the
  absorption of a neutron on 238U, followed by two
  beta decays
• 239Pu also fissions by absorbing a thermal
  neutron, and on average produces 1/3 of the
  energy in a fuel cycle.
• 239Pu is relatively stable, with a half life of
  24 thousand years.
• It is used in nuclear weapons
• It can be bred for nuclear reactors

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Nuclear Weapons to Reactor Fuel

• We are buying highly enriched uranium (20 235U)
  from the former Soviet Unions nuclear weapons
  for 20 years from 1993--2013
• Converting it to low enriched uranium (3 235U)
  for reactor fuel
• It will satisfy 9 years of US reactor fuel demand
• It comes from 6,855 Soviet nuclear warheads so far

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Nuclear Plant Future

• The countries of the world are each planning
  their own course of nuclear plant development or
  decline
• Nuclear power is competitive with natural gas
• It is non-polluting
• It does not contribute to global warming
• Obtaining the fuel only takes 5 of the energy
  output
• Plant licenses have been extended from 20 years
  to an additional 20 years

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Nuclear Plant Future

• Newer designs are being sought to make them more
  economical and safer
• Preapproval of a few designs will hasten
  development
• Disposal of high level radioactive waste still
  being studied, but scientists believe deep burial
  would work
• Because they are have large electrical output,
  their cost at 2 billion is hard to obtain and
  guarantee with banks
• Replacing plants may be cheaper using the same
  sites and containment vessels

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Nuclear Problems and Solutions

• Three Mile Island 1979
• 50 core meltdown, stuck valve with no indicator
  released water, but containment vessel held
• More sensors added, better communication to
  experts in Washington, dont turn off emergency
  cooling
• 28 year US safety record since accident
• Chernobyl 1986
• Human stupidity turned off cooling system
• Poor steam cooling reactor design allowed
  unstable steam pocket to explode
• Graphite caught fire
• Design not used in other countries

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Yucca Mountain Project Nuclear Fuel and High
Level Waste Repository

• Much more secure repository than leaving high
  level waste at 60 reactor sites around the
  country.
• On old atomic bomb testing base, inside a
  mountain.
• The storage is above the water table.
• The Yucca Mountain site would be 60 filled by
  present waste.
• US has legal commitment to the reactor industry.
• Site has been studied extensively by scientists
  for over 20 years.
• Will store waste during its 10,000 year decay
  time.
• Questions of how to deflect dripping water around
  and under the storage vessels.
• Questions of radioactive decay weakening storage
  containers.
• A solution would be to build containers that can
  be opened and reincased, or to which surrounded
  casings could be added.

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Liquid Metal Fast Breeder Reactor

• Uses the fast neutrons from 235U fission on
  surrounding 238U to produce 239Pu
• In 10-20 years, enough Pu is produced to power
  another reactor
• No moderators are allowed
• No water, must use liquid sodium coolant
• U must be at 15-30 enrichment to generate power
  with fast neutrons while breeding Pu
• This is at weapons grade enrichment, however
• Super-Phenix in France has operated for 20 years

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Nuclear Power Proposed Solution?

• Richard Garwin , MIT and industry propose
• If 50 years from now the world uses twice as much
  energy, and half comes from nuclear power
• Need 4,000 nuclear reactors, using about a
  million tons of Uranium a year
• With higher cost terrestrial ore, would last for
  300 years
• Breeder reactors creating Plutonium could extend
  the supply to 200,000 years
• Nonpolluting, non-CO2 producing source
• Need more trained nuclear engineers and sites
• Study fuel reprocessing, waste disposal, and
  safer designs.
• While nuclear reactors have to be on all day and
  night, and power use is less at night, they could
  be used to charge up electric cars.
• Until electric cars or a hydrogen generation
  economy, they might only be used for the 40 of
  generation used at night, up from the present 20
  that they generate.

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Fusion Reactors

• Fusion easiest for Deuteron (D) Tritium(T)
• D(p,n) T(p,nn) ? 4He(pp,nn) n
• in a high temperature plasma.
• Replacement T created from Li blanket around
  reactor
• n 6Li ? 4He T
• Fusion reactors
• International ITER in 2012 for research for a
  decade, costing 5 billion
• Current stalemate over siting in France or Japan
• Followed by DEMO for a functioning plant, taking
  another 10 years.
• Design and completion of a commercial plant not
  until 2050.
• US Lithium supply would last a few hundred years.
• Still would be a radioactive waste disposal
  problem.

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International Thermonuclear Experimental Reactor
(ITER)