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Nuclear Implications and Applications

Explore the implications and applications of nuclear power, from fission reactions to fusion processes, including reactor designs, waste management, and even weapons technology. Learn about nuclear energy's role in generating electricity, space exploration, and more. Gain insights into future advancements and challenges.

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Nuclear Implications and Applications

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  1. Nuclear Implications and Applications

  2. Nuclear Power Diablo Canyon Power Plant, California Source: Jim Zimmerlin, http://www.zimfamilycockers.com/DiabloCanyon.html

  3. Nuclear Power • Nuclear fission reactions release heat (kinetic energy of products) • Heat boils water, powers turbine to generate electricity • No greenhouse gas production

  4. Fission Chain Reaction Source: Griffith

  5. Criticality • Reaction self-sustaining if each fission on average induces another • Critical mass depends on geometry, moderation, reflection, many other factors

  6. Poll Question Which shape of fission fuel will be the most likely to reach criticality? • A sphere. • A plate. • A long, thin cylinder.

  7. Fissile Nuclei • Required for reactors and bombs • Fission started by absorption of thermal neutrons • Only fissile nuclei are U-233, U-235, and Pu-239 • U-235 is less than 1% of natural uranium (rest is U-238)

  8. Plutonium Breeding Source: Griffith

  9. Breeder Reactors • Transmute U-238 to Pu-239 or Th-232 to U-233 • Increase amount of usable fuel

  10. Nuclear Waste Source: Savannah River Site

  11. Nuclear Fuel Cycle • Fission chain reaction produces fission products and neutron capture products • Certain fission products absorb neutrons • Fuel becomes unusable after ~1% burnup • Must be reprocessed or discarded

  12. Poll Question The amount of nuclear waste generated would be reduced if • spent fuel were reprocessed and reused. • all reactors were shut down. • reactors with higher “burn-up” were used. • any of these.

  13. Spent Fuel Hazards Source: Cohen, B. L. Rev. Mod. Phys. 1977, 49, 1–20.

  14. Reprocessing • Recover U, Pu from spent fuel • Discard fission product waste • Possibility of U, Pu diversion

  15. Advanced Reactor Designs • Evaporating moderator • Melt-proof fuel pellets • Higher-burnup design • On-site rapid reprocessing • Fast neutron fission of non-fissile nuclei • Accelerator-based systems

  16. Stellar Fusion NASA photograph, Skylab, 10 December 1973

  17. Think Question What sort of nucleus releases energy by fusion? • Nuclei lighter than iron. • Nuclei about as heavy as iron. • Nuclei heavier than iron.

  18. Fusion in the Sun Source: Seeds, Horizons: Exploring the Universe Net reaction: 4 p+ 4He + 2 e+ + 2 n+ 2 g

  19. Fusion in Hotter Stars Source: Seeds, Horizons: Exploring the Universe Net reaction: 4 p+ 4He + 2 e+ + 2 n+ 3 g

  20. Fusion Life of Massive Stars • Massive star’s hot core fuses atoms to ever-higher masses • Greater nuclear charges require higher temperatures, pressures • Less energy per nucleon from fusing massive nuclei • Fusion energy exhausted at iron

  21. Fusion Death by Supernova • Iron core does not produce energy to resist gravitational collapse of star • High temperature and pressure in shock wave creates more massive nuclei • Some products scattered by explosion All Fe, Cu, W, I, Ag, Au, Pb, U, etc. were released by supernovas!

  22. Nuclear Weapons

  23. Fission Weapons Grable 15-kT yield artillery shell, Nevada Test Site, 25 May 1953. U.S. Department of Energy photo.

  24. Gun Device (“Little Boy”) Source: Griffith

  25. Implosion Device (“Fat Man”) Source: Griffith

  26. Fusion Weapons Dakota 1.1 MT shot, Enewetak, 25 June 1956. U.S Department of Energy photo.

  27. Fusion in Weapons • Require high temperatures to bring nuclei together (thermonuclear) • Heated by fission bomb “pit” 2H + 3H 4He + n

  28. Thermonuclear Device

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