Chapter 11: Nuclear Energy: Benefits & Risks

1. Chapter 11: Nuclear Energy: Benefits & Risks Fact: 7% of energy consumed worldwide comes from nuclear power

4. The Nature of Nuclear Energy • Two types: Fusion and Fission • Fusion • Two or more lighter nuclei combine to form heavier nucleus + energy, e.g., hydrogen fusion to helium • Takes place inside core of Sun • Takes place in an H-bomb • Not feasible as a controlled energy source, too hot to contain

5. The Nature of Nuclear Energy • Fission • heavy nucleus splits into smaller particles + energy • Example: First atomic bombs, like those dropped on Hiroshima & Nagasaki • Can be controlled and used as a source of commercial energy: Nuclear power plants

6. Figure 11.2

7. Nuclear Reactors & Power Generation • Several types, most use Uranium-235 (some Pu-239) as fuel • Energy is released, which is used to heat water to make steam, which is used to turn a turbine to generate electricity • Figure 11.4 =>

8. Nuclear Fuel Cycle fig 11.9 • U-235 is a nonrenewable resource (just like fossil fuels), it is mined (expensive) • Typical uranium ore contains only 0.2% Uranium • Of that 99.3% is U-238 (not usable) and 0.7% U-235 • So, ore must be enriched (expensive) and made into fuel rods • Fuel rods used in reactors last about 3 years, but still have radioactivity left: spent fuel rods => radioactive waste • Disposal of this waste is a major problem

9. Nuclear Waste Disposal • Fuel rods placed in sealed casks, then: • High-level (of radiation) waste disposal • Or, burial in geologically stable area • “NIMBY” problems

10. Yucca Mountain, NV-- fig. 11.18 • http://www.epa.gov/radiation/yucca/

11. Nuclear Power Concerns • No fear of nuclear explosion (like a nuclear bomb) • Greatest fear: if proper safety measures aren’t followed (human error!), reactor can overheat and cause a steam explosion, which throws radioactive material a long distance • Ex: Chernobyl disaster of 1986, pp. 234-235 • Ex: (almost happened) Three-Mile Island, PA ‘79

12. Nuclear Power Concerns... • Exposure to radiation (see table 11.3, p. 237) • Note: Not from nuclear power plants! • Concern is from handling ore, fuel rods, waste • Thermal pollution • water used to cool reactor gets returned to natural water system (lake, river, ocean) • some species are sensitive to temperature • fossil fuel plants also release hot water, but not as much as nucs (1/2 waste heat instead of 2/3)

13. Nuclear Power Concerns... • Decommissioning costs • All power plants have a finite life: 30-40 years • Must then be “decommissioned”, or taken apart in a systematic and careful way: quite expensive to do right ($50 million - $3 billion) • Waste disposal • already discussed

14. Nuclear Power Benefits (?) • Produces no air pollution! • No CO2 (global warming), CO, no nitrogen or sulfur oxides, no volatile organic compounds, no particulate matter • Mining is safer than (underground) coal mining • Very successful in France, where it supplies 73% of its electricity and costs 20 - 30% less than generating electricity by coal • reason: government and public support

15. Nuclear Power Benefits (?) • A good possible transition fuel as fossil fuels become more scarce (until better renewable sources can be developed, recall nuclear energy is not renewable) • Comment: Part of the lack of success of nukes in the U.S. is the propaganda against it, especially after Three-Mile Island and Chernobyl (both of which were caused by human incompetence, not nuclear technology)

16. Anti-Nuclear Propaganda

17. Read “The Nuclear Legacy of the Soviet Union” P. 231, Notice how “we” are blamed for this too!