Transcript nuclear energy released when atom split Fusion

Chapter 12
Nuclear
Energy
Introduction to the Nuclear Process
• Fission –
nuclear energy released when atom split
• Fusion –
nuclear energy released when atoms fused
Introduction to the Nuclear Process
Atoms and Radioactivity
Normally: # protons = # neutrons = # electrons
Neutron (0)
Atomic mass =
# protons + # neutrons
Proton (+)
Electron (-)
Atomic number =
# protons
Nucleus
Introduction to the Nuclear Process
Normally, # proton = # electrons = # neutrons
8P
6P
8N
6N
Oxygen
Carbon
Differing # proton =
different atom
Introduction to the Nuclear Process
6P
8N
If # neutrons > # protons = Isotope
Chemical behavior identical to
normal atom.
Carbon
Many are radioactive
Introduction to the Nuclear Process
Common Radioactive Isotopes
Nuclear Fission
Nuclear Fuel Cycle
Uranium mines
and mills
U-235
enrichment
Fabrication of
fuel assemblies
Nuclear power
plant
Spent fuel
reprocessing
Uranium
tailings
Depleted
uranium tails
Factory
wastes
Low-level
wastes
Spent fuel
stored on-site
Deep geological
disposal
Nuclear Fission
Nuclear Fission
How Electricity is Produced from
Conventional Nuclear Fission
Nuclear Fission
Breeder Nuclear Fission
Pros and Cons of Nuclear Energy
Impact
Coal
Nuclear
Land use
17,000 ac
1,900 ac
Daily fuel
requirement
9,000 tons/day
3 kg/day
Air pollution
Moderate to
severe
Low
Radioactive
emissions
1 curie
28,000 curies
Short-term
local risk
Long-term
risk over
large area
Risk from
catastrophic
accidents
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
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
Safety Issues in Nuclear Power
Plants
• Probability of major accident low,
but if it occurs, consequences are widespread and long-lasting
• Major accidents have included:
Three Mile Island
Chornobyl
Safety Issues in Nuclear Power
Plants
Radioactive fallout from Chornobyl:
Safety Issues in Nuclear Power
Plants
The Link Between Nuclear Energy and
Nuclear Weapons
Can be
Spent fuel from reprocessed
conventional for . . .
nuclear plant
OR
Fuel for
breeder reactor
Nuclear
weapons
Radioactive Wastes
Two general types:
• Low-level radioactive wastes
• High-level radioactive wastes
Radioactive Wastes
Temporary storage includes above-ground
storage casks
Insert Fig 12.10 a, b
Radioactive Wastes
Case-in-Point: Yucca
Mountain
Radioactive Wastes
Other considerations:
• High-Level Radioactive Liquid Waste
• Radioactive Wastes with Relatively Short
Half-Lives
• Decommissioning Nuclear Power Plants
Fusion: Nuclear Energy for the
Future?
Fusion
The Future of Nuclear Power
Issues:
• Making nuclear power safer
• Standardizing power plant designs