Nuclear Energy

1
Nuclear Energy
Chapter 12
2
Introduction to the Nuclear Process

• Fission
• nuclear energy released when atom split
• Fusion
• nuclear energy released when atoms fused

3
Introduction to the Nuclear Process

• Atoms and Radioactivity

Normally protons electrons
Atomic mass protons neutrons
Atomic number protons
4
Introduction to the Nuclear Process
Normally, proton electrons atomic number
5
Introduction to the Nuclear Process
Isotopes are atoms of same element with different
atomic masses, because of differing s of
neutrons. Chemical behavior identical to normal
atom. Some are radioactive.
6
Natural Radioactive Decay

• Unstable isotopes decay by releasing energy,
  particles and becoming new, more stable elements
• Particles released are usually alpha (4He2) or
  beta (oe-1). In addition energy is always
  released.
• Beta emission 14 C 6-gt 14 N 7 oe-1 energy
  (gamma rays)
• Alpha emission 238U92 -gt 234??90 4He2
  energy (gamma rays)
• Half-life time it takes for 1/2 of the unstable
  nuclei to decay by natural radioactivity into
  another element.
• Can vary from seconds to millions of years!

7
Introduction to the Nuclear Process

• Common Radioactive Isotopes

Insert Table 12.1
8
Half-lives how long til its Safe?

• Rule is 10 half-lives to be safe
• If n number of half lives, fraction of original
  remaining after n half-lives 1/2n
• So, if n10, fraction remaining after 10
  half-lives 1/210, or .00098 or .098 (check my
  math!)
• How long for each of the isotopes on previous
  slide to be safe?

9
Radioactive isotopes have many uses

• Radioactive isotopes can be used in medicine, to
  treat cancer (radioactive iodine to treat
  overactive thyroid gland, radioactive cobalt used
  for radiation treatment in certain cancers, and
  used to produce our irradiated seeds.)
• Radioactive isotopes are also useful as tracers
  in biological experiments (can trace where the
  radioactivity goes, to figure out metabolic
  pathways, or to figure out how a chemical
  reaction proceeds.)

10
Ionizing Radiation

• This includes both the particles and energy
  released from radioactive decay.
• Alpha particles cannot penetrate skin, but can be
  lethal if ingested or inhaled (2006 Polonium
  poisoning in UK involving Russian defector )
• Beta particles can penetrate skin, and a lead
  shield is needed to stop gamma rays.
• This radiation can kill cells (why used in cancer
  treatment) and can cause mutations in DNA, which
  could lead to cancer or birth defects.

11
Nuclear Fission

• Nuclear Fuel Cycle

12
Nuclear Fission
13
Nuclear Fission

• How Electricity is Produced from Conventional
  Nuclear Fission

14
Nuclear Fission

• Breeder Nuclear Fission

15
Pros and Cons of Nuclear Energy
Impact
Coal
Nuclear
16
Pros and Cons of Nuclear Energy

• Is Electricity Produced by Nuclear Energy Cheap?
• Role of government subsidies
• The cost of building a nuclear power plant
• Fixing technical and safety problems in existing
  plants

17
Pros and Cons of Nuclear Energy

• Can Nuclear Energy Decrease Our Reliance on
  Foreign Oil?
• Only 3 of electricity in US generated by oil
• Oil primarily used for
• heating buildings
• vehicles

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Safety Issues in Nuclear Power Plants

• Probability of major accident low,
• but if it occurs, consequences are wide-spread
  and long-lasting
• Major accidents have included
• Three Mile Island
• Chornobyl

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Safety Issues in Nuclear Power Plants

• Radioactive fallout from Chornobyl

Insert Fig 12.8
20
Safety Issues in Nuclear Power Plants

• The Link Between Nuclear Energy and Nuclear
  Weapons

Spent fuel from conventional nuclear plant
Fuel for breeder reactor
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Radioactive Wastes

• Two general types
• Low-level radioactive wastes
• High-level radioactive wastes

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Radioactive Wastes

• Temporary storage includes above-ground storage
  casks

23
Waste container
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Low-Level Radioactive Wastes
As many as 20 flatbed trucks deliver
waste containers daily.
Barrels are stacked and surrounded with sand.
Covering is mounded to aid rain runoff.
Up to 60 deep trenches dug into clay.
Clay bottom
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Radioactive Wastes

• Case-in-Point Yucca Mountain
• Proposed repository for high-level radioactive
  wastes.

26
Radioactive Wastes

• Other considerations
• High-Level Radioactive Liquid Waste
• Radioactive Wastes with Relatively Short
  Half-Lives
• Decommissioning Nuclear Power Plants

27
Fusion Nuclear Energy for the Future?

• Fusion

28
The Future of Nuclear Power

• Issues
• Making nuclear power safer
• Standardizing power plant designs