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The Effects of Nuclear Weapons: Terrorist Threat. 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.
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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 • 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 • 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 • 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. • Thermonuclear (Fusion) devices • Unlikely to be a terrorist device • Military application • High-technology
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 • 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 Blast and Thermal account for 85% of the Energy released
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 • 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 • 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
Hiroshima After Hiroshima Before
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) • Peak shock wave overpressure • ~14 psi @ ¼ mile • Thermal energy • ~18 cal/cm2 @ 1 mile • Prompt radiation dose • Neutron ~ 0.8 Gy @ 1 mile • γ-ray ~ 1.2 Gy @ 1 mile
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. • Decay rate: • t can be any time unit • Average photon energy ~0.7 MeV
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 • 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.