Published on January 11, 2008
The Effects of Nuclear Weapons: Terrorist Threat: The Effects of Nuclear Weapons: Terrorist Threat Purpose: Purpose The purpose of this presentation is to provide the reader with an overview of nuclear weapons and their effects. Topics will include: Types of weapons Energy release Types of Detonation Historical Information Effects Nuclear Weapons vs Radioactive Dispersal Device (RDD or Dirty Bomb): Nuclear Weapons vs Radioactive Dispersal Device (RDD or Dirty Bomb) Nuclear weapons Use conventional explosives to create super-critical mass of fissionable nuclear material Super-critical mass is capable of self-sustaining, prompt, uncontrolled chain reaction Resultant explosive yield can be orders of magnitude higher than possible with conventional materials RDD Use conventional explosives to spread or disperse radioactive material No chain reaction or nuclear yield In most cases the explosion will cause more damage than the radioactive material dispersion Remaining discussion: Remaining discussion The remainder of this presentation describes nuclear weapons For further information on RDD weapons see: http://www.bt.cdc.gov/radiation/pdf/dirtybombs.pdf http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/dirty-bombs.pdf Nuclear Weapons Types: Nuclear Weapons Types Fission devices Uranium (235U) or Plutonium (239Pu) Gun Type Explosively combine two sub-critical assemblies Implosion Type Symmetrically implode a sphere of sub-critical density Required for 239Pu Terrorist Threat Stolen military device Improvised Nuclear Device (IND), i.e. “home made” 235U Gun-type Weapon easiest to construct Likely 20 kT or less Nuclear Weapons Types, con’t.: Nuclear Weapons Types, con’t. Thermonuclear (Fusion) devices Unlikely to be a terrorist device Military application High-technology Energy Equivalents of one Kiloton of TNT: Energy Equivalents of one Kiloton of TNT Complete burn-up (fission) of 56 g (~2 ounces) of 235U or 239Pu 1.15 x 106 kilowatt-hours 1.8 x 109 British thermal units 14,500 Gallons of Gasoline 4/5 the energy produced by the Hoover Dam in 1 hour Types of Detonations from a Terrorist Threat: Types of Detonations from a Terrorist Threat Most likely Surface: Truck Underwater: Boat Less likely Air: Private plane Sub-surface: Subway Least likely High Altitude: Military Delivery Only Distribution of Energy of an Air Burst below 100,000 ft: Distribution of Energy of an Air Burst below 100,000 ft Blast and Thermal account for 85% of the Energy released Nuclear Weapon Experience Two non-testing detonations: Nuclear Weapon Experience Two non-testing detonations Hiroshima Little Boy 235U Gun-Type Device Nagasaki Fat Man 239Pu Implosion Device Results of a Nuclear Explosion: Results of a Nuclear Explosion 80,000 deaths in Hiroshima and 20,000 deaths in Nagasaki Nearly all deaths due to Blast and Thermal Few deaths attributed to Radiation Prompt or Delayed Results of a Nuclear Explosion: Results of a Nuclear Explosion Expect few, if any, survivors near ground-zero However, little experience in “urban” environment Buildings will provide shielding Blast Thermal Radiation Residual radioactive environment, significant impact on rescue operations Slide13: Hiroshima Before Hiroshima After Weapon Effects: Weapon Effects Prompt effects higher with airburst Blast Thermal Prompt Radiation Prompt effects 30-50% reduced with surface burst Electromagnetic Pulse (EMP) Primarily results from a high-altitude explosion Not a likely effect from a terrorist detonation Residual effects higher with surface burst Residual Radioactivity (Fallout) Weapon Effects(Based on a 20 kt low-altitude Airblast): Weapon Effects (Based on a 20 kt low-altitude Airblast) Peak shock wave overpressure ~14 psi @ ¼ mile Thermal energy ~18 cal/cm2 @ 1 mile Prompt radiation dose Neutron ~ 0.8 Gy @ 1 mile g-ray ~ 1.2 Gy @ 1 mile Residual Radiation (Fallout): Residual Radiation (Fallout) Difficult to predict impact to a specific area Depends on: Type of weapon Type of burst Air Surface Wind patterns Terrain Little data for an “Urban” Environment Fallout, con’t.: Fallout, con’t. Decay rate: t can be any time unit Average photon energy ~0.7 MeV Summary: Summary A terrorist use of a nuclear weapon would most likely involve: 235U Gun-type device Surface detonation Yield of 20 kt or less The major injuries and effects would be caused by: Blast and shock Thermal Rescue efforts pertain mostly to injuries distant from ground zero Radiation protection necessary for rescue of shielded survivors nearer ground zero Little experience with explosion in an “Urban” environment References: References Glasstone and Dolan, “The Effects of Nuclear Weapons,” Published by US DoD and Energy Research and Development Administration, Washington DC, 1977. Ferguson and Potter, “The Four Faces of Nuclear Terrorism,” Monterey Institute – Center for Nonproliferation Studies, Monterey, CA, 2004. Auxier J, “The Effects of Nuclear Weapons,” Health Physics Summer School, Gaithersburg, MD, July 2004. Public Protection from Nuclear, Chemical and Biological Terrorism, Ed. by Brodsky, Johnson and Goans, Medical Physics Publishing, Madison, WI, 2004.