Announcements

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Announcements

• Today Nuclear energy,
• Conventional Energy
• Wed Alternative Energy, Biofuels
• Friday Summary, evaluations
• Dec 12 Final exam 6-8 PM 200 points
• 50 True /false Multiple Choice---3 points each
• 40 from previous two exams
• 10 from new set of ?s
• (Short Answer ) 50 points
• answer two of three
• Synthetic essays

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ENERGYMonday, Wednesday

• Nuclear Energy
• Nuclear Waste
• The US Energy Stream
• Fossil Fuels
• Green Energy

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How Nuclear Power grew in the US

• Virtually no new capacity since mid 1990s

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Current Nuclear Power
Nuclear power provides 20 of all US electrical
power
Note this is a of energy budget. US is the 1
producer of nuclear energy
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And the US Government?
How?
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Reactor?
Current Practice
Hope for future
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Why is radiation bad for living organisms?
Half life

• At high levels it causes damage to DNA and
  prevents cells from undergoing cell division.
• At low levels, it acts as an enhancer for
  altering DNA controls over cell division and can
  cause cancer.
• eg, it is thought that a by-product of Chernobyl
  could be as high as 150,000 to 500,000 cancer
  deaths in the region. (numbers hotly debated)

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Radiation exposure
Is a natural process and radiation exists all
around us in the world at very low levels. Some
molecules are very stable, others very unstable
(meaning they are more or less likely to decay
mSV millisieverts 100-500 msv Increased
cancer risk
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Nuclear Fission Facts

• Initial product Uranium isotope- 235U
• Naturally decays, but half life is 700 million
  years!
• 99.3 of uranium is 238U, 0.7 235U, 0.005 is
  234U
• Enriched uranium is a process to concentrate 235U
  in ore.
• decays, meaning it loses neutrons or protons
  in a random process.
• We define a half-life as the average length of
  time it takes for ½ of the isotopic molecules to
  spontaneously lose a neutron or proton (decay)
• The by-products of bombarding 235U with neutrons
  is other radioactive material, including plutonium

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Nuclear Wastes

• Difficulties associated with nuclear power
  include disposal of wastes produced during
• mining,
• fuel production, and
• reactor operation.
• Options
• Ocean dumping
• Burying radioactive mine wastes, mill tailings
• Dry cask storage
• High-level waste repository - Yucca Mountain
• Monitored, retrievable storage?

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Nuclear Waste By-Products
EPA requires storage for 20 half-lives. 97 of
nuclear waste is dead in 10 years. The last
bit, plutonium lasts for 24,000 yrs for 1
half-life
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Safety Issues

• Control of plutonium accessibility
• Nuclear disasters
• Storage of nuclear waste

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1. Plutonium access

• One of the by-products of standard nuclear power
  generation is plutonium.
• Plutonium is used to make a high grade
  radioactive fuel for nuclear weapons.
• North Korea and weapons program
• Control is problematic (James Bond-type movies)
• Radioactive cobalt went missing in Iraq
• Plutonium missing at Los Alamos in 2005?

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2. Disasters 1979 Three Mile Island A close
call on a meltdown

• Steam generator shut down automatically because
  feedwater pumps lost power
• A pressure valve opened to release pressure
• This valve stuck open draining the system of
  coolant water
• No sensor detected that the cooling tanks were
  empty
• The reactor core heated up too much (partial
  meltdown) and radioactive gas was emitted to
  atmosphere.

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Disasters Chernobyl A meltdown

• Two engineers running a test of a stand-by diesel
  generator, took safety controls off line
• Disabled coolant to reactor, but did not account
  for radioactive heat that continued to be
  generated
• Reactor heated up, steam could not be released
• Steam and heat boosted nuclear reactions in core
• Engineers inserted carbon tipped rods to control
  reactions. This increased nuclear reactions by
  further slowing neutrons

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• The result the explosion blew the 2000 ton top
  off the reactor.
• 90 million curies of radioactivity released in a
  plume that settled over 1000s of sq miles
• 2 people died initially, 31 emergency personnel
  brought in to fight disaster also died later of
  poisoning. 135,000 evacuated
• 1000 sq mi fenced off area.
• 2 other reactors still in operation.
• Workers bussed in

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Chernobyl - 1986
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3. Waste storageRegulation

• Nuclear Waste Policy Act. 1997.
• Different versions passed by House and Senate in
  1997.
• Bills could not be reconciled in committee, so
  was never signed by President
• Department of Energy is in charge
• Issue storage of nuclear waste
• Dakotas and SW Native American tribes leading
  candidates
• Yucca mountain, on the nuclear testing grounds in

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Dumped Nuclear Reactors - Kara Sea
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Who wants it near them?LULU locally unwanted
land use

• Everyone remembers these issues when thinking of
  nuclear power
• It is said that safety is much improved in newer
  plants
• Not In My Back Yard (NIMBY)
• Problem with finding a long-term storage site
• Nevada governor vetoed choice of site, but was
  over-riden by US Congress (how does that work?)
• Nuclear by-products equally disliked

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The Yucca Mountain Project
After more than 20 years and 4 billion in
scientific study, the U.S. Congress approved
Yucca Mountain, Nevada, as the nations first
long-term geologic repository for spent nuclear
fuel and high-level radioactive waste. "The
Senate has rightfully chosen to allow the process
of developing a nuclear waste repository at Yucca
Mountain to proceed to the next step, recognizing
that the independent experts at the Nuclear
Regulatory Commission (NRC) deserve the right to
review the 24 years of scientific study of Yucca
Mountain and to consider the site for a license,"
said Energy Secretary Spencer Abraham following
the July 9, 2002, vote.
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Dry Cask Storage
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Storing Nuclear Waste

• Underground
• Groundwater pollution
• Yucca Mountain has very deep groundwater and
  little rainfall
• Demonstrable lack of volcanic activity or
  earthquakes
• Yucca mountain is not very active (in theory)

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We are somewhere in here

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2006
Nevada TV station
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Alternative Nuclear Power

• Breeder Reactor
• Uses plutonium by breeding 238U into 239PU by
  the addition of a neutron
• This greatly increases the volume of potential
  nuclear fuel, since 99.3 of all U is 238U
• Plutonium (239PU ) is what goes into nuclear
  weapons
• 239PU is also a by-product of fission reactors
• Iraq, North Korea, Pakistan. said they were
  using breeder reactors for power, but US
  concerned that they are for nuclear weapons

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Alternative Nuclear Power

• Fusion
• 2 H to He
• Same process as H-bomb
• Super heat H20 with heavy H, (deuterium, tritium)
  to release H
• Still a net energy drain
• We put more energy into heating up the Hydrogen
  than we get out of the fusion reaction

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The big three
OIL
Coal
Natural Gas
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U.S. Energy Flow, 1999
USE
SUPPLY
Quantities in BTUs.
Important point
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Viewpoint 1 The world is running out of oil
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View 2 Much of the world is underlain with some
kind of recoverable petroleum. It just gets more
difficult and more expensive, so until we
actually encounter a situation where supply is
not meeting demand, we wont develop these
resources