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Chapter 12 Nuclear Energy. Overview of Chapter 12. Introduction to Nuclear Power Nuclear Fission Pros and Cons of Nuclear Energy Safety Issues at Power Plants Radioactive Waste Future of Nuclear Power. Introduction to Nuclear Energy.

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Chapter 12 nuclear energy

Chapter 12Nuclear Energy


Overview of chapter 12
Overview of Chapter 12

  • Introduction to Nuclear Power

  • Nuclear Fission

  • Pros and Cons of Nuclear Energy

  • Safety Issues at Power Plants

  • Radioactive Waste

  • Future of Nuclear Power


Introduction to nuclear energy
Introduction to Nuclear Energy

  • Nuclear Energy - the energy released by nuclear fission or fusion

  • Henri Becquerel

  • Marie Curie (right)

  • Ernest Rutherford


Introduction to nuclear energy1
Introduction to Nuclear Energy

  • Nuclear energy

    • Energy released by nuclear fission or fusion

  • Nuclear fission

    • Splitting of an atomic nucleus into two smaller fragments, accompanied by the release of a large amount of energy

  • Nuclear fusion

    • Joining of two lightweight atomic nuclei into a single, heavier nucleus, accompanied by the release of a large amount of energy


Atoms and radioactivity
Atoms and Radioactivity

  • Nucleus

    • Comprised of protons (+) and neutrons (neutral)

  • Electrons (–) orbit around nucleus

  • Neutral atoms

    • Same # of protons and electrons


Atoms and radioactivity1
Atoms and Radioactivity

  • Atomic mass

    • Sum of the protons and neutrons in an atom

  • Atomic number

    • Number of protons per atom

    • Each element has its own atomic number

  • Isotope

    • Atom where the number of neutrons is greater than the number of protons


Radioactive isotope
Radioactive Isotope

  • Unstable isotope

  • Radioactive Decay

    • Emission of energetic particles or rays from unstable atomic nuclei

  • Example

    • Uranium (U-235) decays over time to lead (Pb-207)

  • Each isotope decays based on its own half-life



Nuclear fission
Nuclear Fission

  • Nuclear Fuel Cycle

    • processes involved in producing the fuel used in nuclear reactors and in disposing of radioactive (nuclear) wastes




Breeder nuclear fission
Breeder Nuclear Fission

  • A type of nuclear fission in which non-fissionable U-238 is converted into fissionable Pu-239


Pros and cons of nuclear energy
Pros and Cons of Nuclear Energy

  • Pros

    • Less of an immediate environmental impact compared to fossil fuels

    • Carbon-free source of electricity

    • May be able to generate H-fuel

  • Cons

    • Generates radioactive waste

    • Many steps require fossil fuels (mining and disposal)

    • Expensive



Cost of electricity from nuclear energy
Cost of Electricity from Nuclear Energy

  • Cost is very high

  • 20% of US electricity is from Nuclear Energy

    • Affordable due to government subsidies

  • Expensive to build nuclear power plants

    • Long cost-recovery time

  • Fixing technical and safety issues in existing plants is expensive


Safety issues in nuclear power plants
Safety Issues in Nuclear Power Plants

  • Meltdown

    • At high temperatures the metal encasing the uranium fuel can melt, releasing radiation

  • Probability of meltdown is low

  • Public perception is that nuclear power is not safe

  • Sites of major accidents:

    • Three Mile Island

    • Chornobyl (Ukraine)


Three mile island
Three-Mile Island

  • 1979 - most serious reactor accident in US

  • 50% meltdown of reactor core

    • Containment building kept radiation from escaping

    • No substantial environmental damage

    • No human casualties

  • Elevated public apprehension of nuclear energy

    • Led to cancellation of many new plants in US


Chornobyl
Chornobyl

  • 1986 - worst accident in history

  • 1 or 2 explosions destroyed the nuclear reactor

    • Large amounts of radiation escaped into atmosphere

  • Spread across large portions of Europe


Chornobyl1
Chornobyl

  • Radiation spread was unpredictable and uneven

  • Death toll is

    10,000–

    100,000


Nuclear energy and nuclear weapons
Nuclear Energy and Nuclear Weapons

  • 31 countries use nuclear energy to create electricity

  • These countries have access to spent fuel needed to make nuclear weapons

  • Safe storage and handling of these weapons is a concern


Radioactive wastes
Radioactive Wastes

  • Low-level radioactive waste

    • Radioactive solids, liquids, or gases that give off small amounts of ionizing radiation

  • High-level radioactive waste

    • Radioactive solids, liquids, or gases that give off large amounts of ionizing radiation


Radioactive wastes1
Radioactive Wastes

  • Long term solution to waste

    • Deep geologic burial – Yucca Mountain

    • As of 2004, site must meet EPA million year standard (compared to previous 10,000 year standard)

    • Possibilities:

      • Above ground mausoleums

      • Arctic ice sheets

      • Beneath ocean floor


Radioactive waste
Radioactive Waste

  • Temporary storage solutions

    • In nuclear plant facility (require high security)

      • Under water storage

      • Above ground concrete and steel casks

  • Need approved permanent options soon.


Case in point yucca mountain
Case-In-Point Yucca Mountain

  • 70,000 tons of high-level radioactive waste

  • Tectonic issues have been identified


Decommissioning nuclear power plants
Decommissioning Nuclear Power Plants

  • Licensed to operate for 40 years

    • Several have received 20-year extensions

  • Power plants cannot be abandoned when they are shut down

  • Three solutions

    • Storage

    • Entombment

    • Decommissioning (dismantling)


Attitudes towards nuclear power
Attitudes Towards Nuclear Power

  • NIMBY - Not In My BackYard

    • Citizens to not want a nuclear facility or waste disposal site near their home

  • Dad- Decide, Announce, Defend

    • Pronuclear advocates

    • Based on the science, not fears


Fusion
Fusion

  • Fuel= isotopes of hydrogen


Fusion1
Fusion

  • Way of the future?

    • Produces no high-level waste

    • Fuel is hydrogen

  • Problems

    • It takes very high temperatures (millions of degrees) to make atoms fuse

    • Confining the plasma after it is formed

  • Scientists have yet to be able to create energy from fusion