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Nuclear Weapons

Nuclear Weapons. Units of Radiation Dose. Roentgen – Ability to create a specified electric charge per volume of air Rem (Roentgen equivalent man) –Biological effect of one roentgen of X-rays Rad (Radiation absorbed dose) – Energy absorption: 400,000 rads heat H 2 O 1 deg

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Nuclear Weapons

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  1. Nuclear Weapons

  2. Units of Radiation Dose • Roentgen – Ability to create a specified electric charge per volume of air • Rem (Roentgen equivalent man) –Biological effect of one roentgen of X-rays • Rad (Radiation absorbed dose) – Energy absorption: 400,000 rads heat H2O 1 deg • For general human exposure, these units are roughly equivalent

  3. Background Radiation • Cosmic Rays • Solar Wind • Decay of Natural Radioactivity • Typical Doses • Global Average 0.1 rem/year (80% natural) • Some areas up to 1 rem/year • Ramsar, Iran: up to 26 rem/year

  4. Human Radiation Sources • Nuclear Fallout from Atmospheric Testing (US and Russia, 1963; France, 1974; China, 1980) • Chernobyl 1986 • Uranium Mining • Radon release from construction and earth-moving • Conventional power plants

  5. Human Survival Limits • 200 rem (whole body): few immediate fatalities • 500 rem (whole body): 50% fatalities • 1000 rem (whole body): No survivors

  6. Chain Reaction

  7. Nuclear Fission • Chain reaction requires a critical mass to proceed • 10 kg U-235 = 2.5 x 1025 atoms • 1,2,4,8 … 2.5 x 1025 = 85 steps • @ 1/1,000,000 sec per step = 1/10,000 sec • After 64 steps, T = 10,000 K (twice as hot as sun) • Have only completed 1/1,000,000 of fission

  8. Nuclear Weapons To get a nuclear explosion, you have to • Assemble a critical mass in millionths of a second • Retain a high percentage of the neutrons • Hold the material together against temperatures hotter than the Sun • Imposes limits on yield of weapon • Unless something is specifically designed to be a nuclear weapon, it will not explode

  9. Yields of Nuclear Weapons • Kiloton = 1000 tons of explosives = 4.2 x 1012 joules = 1012 calories • Texas City, Texas, April 16-17, 1947 • Collapse of World Trade Center • Impact of 10-m asteroid • Megaton = 1,000,000 tons of explosives = 4.2 x 1015 joules = 1015 calories • Magnitude 7 earthquake • Impact of 100-m asteroid

  10. “Das war keine gute Idee”

  11. Effects of Nuclear Weapons • Direct ionizing radiation • Heat (Fireball) • Rising fireball sucks dust upward, creates “mushroom cloud” • Any large explosion will create a “mushroom cloud” • Blast (Expansion of Fireball) • Fallout • Volume α Yield: Radius α3√Yield

  12. All Large Explosions Make Mushroom Clouds

  13. Nuclear Explosion

  14. Weapons Terminology • Warhead: The Actual Explosive Component of a Nuclear Weapon • Warhead Section: The Delivery Casing for a Nuclear Weapon. Includes casing, radars, timers, detonators, etc • When most people say “Warhead,” they actually mean “Warhead Section.” • Tactical = Range < 500 km • Strategic = Range > 500 km

  15. Some Nuclear Factoids • Nuclear weapons are always under armed guard • Nobody Ever Goes Near a Nuke Alone. U.S. Protocols Call for a “Two Man” Rule • There are persistent rumors we allowed designs of our locking mechanisms to be leaked to the Russians • Information on locations of nuclear weapons is classified “Secret” or above • Do not confirm/deny

  16. Nuclear Weapons Systems • All military explosive weapons have had nuclear versions • Artillery Shells • Bombs • Depth Charges • Rockets • Missiles • Anti-Aircraft • Stationary charges

  17. DASA and SASCOM

  18. “Little Boy” Gun Type, Uranium

  19. “Fat Man” Implosion, Plutonium

  20. Early Strategic Nuke

  21. Early Strategic Nuke

  22. Trinitite

  23. Atomic Bomb

  24. Delivery Systems

  25. Titan Warhead

  26. Minuteman Warheads

  27. MinutemanWarheads

  28. Minuteman Missile Silo, SD

  29. MIRV

  30. Tactical Nukes

  31. Nuclear Artillery Shell

  32. Atomic Cannon

  33. “Birdcage” for Artillery Shell Fissionable Material

  34. Davy Crockett

  35. SADM

  36. MADM

  37. Cradle For Nuclear Artillery Shell

  38. Palomares, Spain: My Bad

  39. Russian Nukes

  40. Nuclear Winter • Publicized by Carl Sagan and others in 1980’s • Global nuclear exchange would raise large amounts of dust and soot into upper atmosphere • Would absorb or reflect sunlight, cooling the surface • Would be above most precipitation processes • Did not happen in Gulf War 1991

  41. Fusion • Natural: how stars (and the sun) generate energy • Artificial and uncontrolled: Thermonuclear Weapon (hydrogen bomb) • Fusion Reactor: controlled • “Energy source of the future. Always has been, always will be.”

  42. Core of the Sun • Energy output: 90 billion megatons/second • Energy output = 6 microwatts/kg – less than a candle • Human body outputs 1.2 W/kg – 200,000 times greater • Trying to duplicate sun’s energy output not practical on Earth • Energy takes 10,000 – 100,000 years to reach surface

  43. Uncontrolled Fusion • We cannot achieve T and P necessary to use ordinary hydrogen • Have to use H-2 (deuterium) or H-3 (tritium) • Still need T = 1,000,000 K+ • Initiated by a nuclear (fission) weapon • Fission weapons yield up to 20 kilotons • Fusion (hydrogen or thermonuclear) weapons yield up to 20 megatons

  44. Controlled Fusion • Temperatures too high for any material • Need to contain by magnetic fields, achieve small-scale reactions for short periods • Have not achieved break-even • Apparatus will be incredibly complex and expensive • Reactions give off neutrons: there will still be radioactive waste • No spent fuel or fissionable residue

  45. Detecting Nuclear Explosions • Vela System (US) • Space: X-ray and Gamma Ray pulses • Atmospheric: • Double-humped light pulse • Initial Fireball • Obscured by ionized gas in shock wave • Revealed again as shock wave cools • Vela Incident, September 22, 1979 • Subsurface: Seismic First Motion Analysis

  46. Nuclear Powers and Wannabes

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