View
246
Download
0
Category
Tags:
Preview:
Citation preview
Chapter 12Chapter 12Nuclear EnergyNuclear Energy
Introduction to Nuclear Introduction to Nuclear EnergyEnergy Nuclear Energy - Nuclear Energy -
the energy released the energy released by nuclear fission or by nuclear fission or fusionfusion
Atoms and RadioactivityAtoms and Radioactivity
Nucleus Nucleus Comprised of Comprised of
protons (+) and protons (+) and neutrons (neutral)neutrons (neutral)
Electrons (–) orbit Electrons (–) orbit around nucleusaround nucleus
Introduction to Nuclear Introduction to Nuclear EnergyEnergy Nuclear energyNuclear energy
Energy released by nuclear fission or fusionEnergy released by nuclear fission or fusion Nuclear fissionNuclear fission
Splitting of an atomic nucleus into two Splitting of an atomic nucleus into two smaller fragments, accompanied by the smaller fragments, accompanied by the release of a large amount of energyrelease of a large amount of energy
Nuclear fusionNuclear fusion Joining of two lightweight atomic nuclei into Joining of two lightweight atomic nuclei into
a single, heavier nucleus, accompanied by a single, heavier nucleus, accompanied by the release of a large amount of energy the release of a large amount of energy
Atoms and RadioactivityAtoms and Radioactivity
Atomic massAtomic mass Sum of the protons and neutrons in an Sum of the protons and neutrons in an
atomatom Atomic numberAtomic number
Number of protons per atomNumber of protons per atom Each element has its own atomic numberEach element has its own atomic number
IsotopeIsotope Atom where the number of neutrons is Atom where the number of neutrons is
greater than the number of protonsgreater than the number of protons
Radioactive IsotopeRadioactive Isotope
Unstable isotopeUnstable isotope Radioactive DecayRadioactive Decay
Emission of energetic particles or rays Emission of energetic particles or rays from unstable atomic nucleifrom unstable atomic nuclei
ExampleExample Uranium (U-235) decays over time to Uranium (U-235) decays over time to
lead (Pb-207)lead (Pb-207) Each isotope decays based on its Each isotope decays based on its
own half-lifeown half-life
Radioactive Isotope Half-Radioactive Isotope Half-liveslives
Nuclear FissionNuclear Fission
How Electricity is ProducedHow Electricity is Produced
Breeder Nuclear FissionBreeder Nuclear Fission
A type of nuclear fission in which A type of nuclear fission in which non-fissionable U-238 is converted non-fissionable U-238 is converted into fissionable Pu-239 into fissionable Pu-239
Pros and Cons of Nuclear Pros and Cons of Nuclear EnergyEnergy ProsPros
Less of an immediate environmental Less of an immediate environmental impact compared to fossil fuelsimpact compared to fossil fuels
Carbon-free source of electricityCarbon-free source of electricity May be able to generate H-fuelMay be able to generate H-fuel
ConsCons Generates radioactive wasteGenerates radioactive waste Many steps require fossil fuels (mining Many steps require fossil fuels (mining
and disposal)and disposal) ExpensiveExpensive
Pros and Cons of Nuclear Pros and Cons of Nuclear EnergyEnergy
Cost of Electricity from Cost of Electricity from Nuclear EnergyNuclear Energy
Cost is very highCost is very high 20% of US electricity is from Nuclear 20% of US electricity is from Nuclear
EnergyEnergy Affordable due to government subsidiesAffordable due to government subsidies
Expensive to build nuclear power Expensive to build nuclear power plantsplants
Fixing technical and safety issues in Fixing technical and safety issues in existing plants is expensiveexisting plants is expensive
Safety Issues in Nuclear Safety Issues in Nuclear Power PlantsPower Plants
MeltdownMeltdown At high temperatures the metal encasing At high temperatures the metal encasing
the uranium fuel can melt, releasing the uranium fuel can melt, releasing radiation radiation
Probability of meltdown is lowProbability of meltdown is low Public perception is that nuclear power Public perception is that nuclear power
is not safeis not safe Sites of major accidents:Sites of major accidents:
Three Mile IslandThree Mile Island Chornobyl (Ukraine)Chornobyl (Ukraine)
Three-Mile IslandThree-Mile Island
1979 - most serious reactor accident in 1979 - most serious reactor accident in USUS
50% meltdown of reactor core50% meltdown of reactor core Containment building kept radiation from Containment building kept radiation from
escapingescaping No substantial environmental damageNo substantial environmental damage No human casualtiesNo human casualties
Elevated public apprehension of Elevated public apprehension of nuclear energynuclear energy Led to cancellation of many new plants in Led to cancellation of many new plants in
USUS
ChornobylChornobyl
1986 - worst 1986 - worst accident in accident in historyhistory Large amounts of Large amounts of
radiation escaped radiation escaped into atmosphereinto atmosphere
ChornobylChornobyl
Radiation spread was unpredictable Radiation spread was unpredictable and unevenand uneven
Radioactive WastesRadioactive Wastes
Long term solution to Long term solution to wastewaste Deep geologic burial – Deep geologic burial –
Yucca MountainYucca Mountain As of 2004, site must As of 2004, site must
meet EPA million year meet EPA million year standard standard
Possibilities:Possibilities: Above ground mausoleumsAbove ground mausoleums Arctic ice sheetsArctic ice sheets Beneath ocean floorBeneath ocean floor
Radioactive WasteRadioactive Waste
Temporary storage solutionsTemporary storage solutions In nuclear plant facility (require high In nuclear plant facility (require high
security)security) Under water storageUnder water storage Above ground concrete and steel casksAbove ground concrete and steel casks
Need approved permanent options Need approved permanent options soon.soon.
Decommissioning Nuclear Decommissioning Nuclear Power PlantsPower Plants Licensed to operate for 40 yearsLicensed to operate for 40 years
Several have received 20-year extensionsSeveral have received 20-year extensions Power plants cannot be abandoned Power plants cannot be abandoned
when they are shut downwhen they are shut down Three solutionsThree solutions
StorageStorage EntombmentEntombment Decommissioning (dismantling)Decommissioning (dismantling)
Recommended