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Please be Seated

Explore the structure of the nucleus, nuclear reactors, radiation, and the electromagnetic spectrum. Learn about the different atomic models, stable nuclides, and nuclear fission and fusion. Discover the advantages of nuclear power and its useful applications. Understand radiation exposure and its effects on the environment and human health.

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Please be Seated

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  1. PleasebeSeated

  2. The Nucleus Physics is Phun October/November 2008

  3. Topics:Nuclear structureNuclear reactorsNuclear radiationUseful radiation effects

  4. Nu-cle-ar good  Nu-cu-lar not so good 

  5. The Electromagnetic Spectrum “Waves” “Photons” c = f λ c = the speed of light f = frequency λ = wavelength E = h f E = photon energy h = Planck’s constant f = frequency

  6. Infrared Visible light Ultraviolet

  7. “Members” of theElectromagnetic Spectrum

  8. Atomic models:1. the “plum-pudding” model2. the “nuclear” model(tiny nucleus with electronsin much larger orbits) Beryllium atom (without neutrons!!)

  9. The Hydrogen Balmer Series

  10. The Nucleus1. Protons (positive charge)2. Neutrons (neutral charge)3. Nuclear Diameter ~10-15 m(atomic diameter ~10-10 m) The term “nucleon” refers to either a proton or a neutron in the nucleus. The term “nuclide” refers to a nucleus with a specific number of protons and neutrons.

  11. The Chart of Nuclides

  12. Stable Nuclides All Known Nuclides

  13. Nuclear models:1. the “water-drop” model2. the “shell” model Models describe aspects of the structure of nuclei and how they behave.

  14. The water-drop modelall nucleons “undifferentiated”binding energy is equally distributed

  15. Binding Energy BE = M(Z protons) + M(N neutrons) – M(Nucleus) Atomic Number: A = Z + N BE is the energy required to separate the full nucleus into its individual protons and neutrons E = mc2

  16. Average Binding energy per nucleon

  17. Applications of thewater-drop model1. Nuclear fission (very large nuclei break up)2. Nuclear fusion(very small nuclei fuse together)

  18. Nuclear fission235U + n –—> small nuclei + neutrons + ENERGY!!n + 235U –—> another fissioncreating a “chain reaction”

  19. Vibrating water drop Click title above to see video

  20. Critical Mass Click title above to see video

  21. NuclearChain ReactionMousetrap Model Click title above to see video

  22. Uncontrolled fission:Atomic bomb(235U or 239Pu bomb)Controlled fission:Nuclear reactor

  23. Pressurized Water Reactor From: Joseph Gonyeau, P.E., Virtual Nuclear Tourist http://www.nucleartourist.com/

  24. Advantages of Nuclear Power:1. Clean (no air pollution, including greenhouse gases)2. Safe compared with other fuels3. Price competitive with fossil fuels4. 100 year supply of 235U5. Infinite supply (>10,000 years) of 238U (if we use breeder reactors)

  25. Patrick Moore*: Going Nuclear A Green Makes the Case (for Nuclear Power) OUTLOOK, Washington Post, April 16, 2006 *Co-founder of Greenpeace (ca. 1970)

  26. In the early 1970s when I helped found Greenpeace, I believed that nuclear energy was synonymous with nuclear holocaust, as did most of my compatriots. ….

  27. …. Thirty years on, my views have changed, and the rest of the environmental movement needs to update its views, too, because nuclear energy may just be the energy source that can save our planet from another possible disaster: climate change.

  28. "It doesn’t matter what is true; what matters is what people think is true." Founder, Greenpeace (2000)

  29. UM Reactor Core Blue Cerenkov radiation

  30. UM Reactor Core Blue Cerenkov radiation Not green, Homer!

  31. Nuclear fusion 2D + 2D –—> larger nuclei + LOTS OF ENERGY!!

  32. Average Binding energy per nucleon

  33. “Theta Pinch”electromagnetic squeezingto produce fusion

  34. Nuclear Shell ModelDiscrete energy levelsfor protons and neutronsanddiscrete energies for radiationwhen energy levels changeor following radioactive decay

  35. Radiation types:Alpha particle (2 Ps + 2 Ns: 4He nucleus)Beta particle (- or + electron)Gamma ray (photon energy packet)NeutronsCosmic Rays

  36. Radiation Exposure

  37. Sources of radiation exposure:1. Natural Exposure2. Man-made Exposure

  38. Natural Exposure:1. Radon gas2. Cosmic Rays3. External Environment4. Internal: The Body

  39. 238U Decay Chain

  40. Cosmic Rays:1. Cosmic ray muons2. Other particles

  41. Cosmic Radiation

  42. Man-made radiation:1. X-rays and γ-rays2. Nuclear medicine3. Consumer products (food, etc.)

  43. Sources of Radiation Exposure From: National Institutes of Health

  44. Useful Radiation Effects INuclear PowerMedical: Diagnostic scans, tracers Magnetic resonance imaging Cancer radiation treatment Plutonium powered pacemaker Medical, dental sterilization

  45. Useful Radiation Effects IIPolymer cross-linking Shrink tubing (eg., turkey wrapping) Ultra-strong materials (eg Kevlar) Tires (replaces vulcanization) FlooringFood irradiation Sterilization of meat Disinfestation of grain and spices Increase shelf life (eg, fruits, veggies)

  46. The “radura.”

  47. Useful Radiation Effects IIIAbsolute sterilization of food: hospitals and space travel Radioactive dating Insect control Semiconductor doping Testing of space computer technology Environmental studies: air purity, global warming, ozone

  48. The Nuclear Waste Test

  49. Test Question #1 Suppose that all of the electrical energy for the world for the next 500 years were obtained from nuclear reactors. Further suppose that all of the nuclear waste from these reactors were dissolved and spread uniformly throughout the oceans of the world.

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