The Effects of Nuclear Weapons: Terrorist Threat

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The Effects of Nuclear Weapons Terrorist Threat
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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

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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

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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

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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

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Nuclear Weapons Types, cont.

• Thermonuclear (Fusion) devices
• Unlikely to be a terrorist device
• Military application
• High-technology

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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

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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

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Distribution of Energy of an Air Burst below
100,000 ft
Blast and Thermal account for 85 of the Energy
released
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Nuclear Weapon Experience Two non-testing
detonations

• Hiroshima
• Little Boy
• 235U Gun-Type Device
• Nagasaki
• Fat Man
• 239Pu Implosion Device

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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

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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

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Hiroshima Before
Hiroshima After
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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)

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Weapon Effects(Based on a 20 kt low-altitude
Airblast)

• Peak shock wave overpressure
• 14 psi _at_ ¼ mile
• Thermal energy
• 18 cal/cm2 _at_ 1 mile
• Prompt radiation dose
• Neutron 0.8 Gy _at_ 1 mile
• g-ray 1.2 Gy _at_ 1 mile

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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

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Fallout, cont.

• Decay rate
• t can be any time unit
• Average photon energy 0.7 MeV

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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

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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.