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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 weaponsEnergy releaseTypes of DetonationHistorical InformationEffects. Nuclear Weapons vs Radioactive Dispersal Device (RDD or Dirty Bomb). Nuclear weaponsUse conventional explosives to create super-critical mass of fissionable nuclear materialSuper-critical mass is capable of self-sustaining, prompt, uncontrolled chain reactionResultant32768
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1. The Effects of Nuclear Weapons: Terrorist Threat
2. 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
3. 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
4. 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
5. 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
6. Nuclear Weapons Types, con’t. Thermonuclear (Fusion) devices
Unlikely to be a terrorist device
Military application
High-technology
7. 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
8. 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
9. Distribution of Energy of an Air Burst below 100,000 ft
10. Nuclear Weapon Experience Two non-testing detonations
Hiroshima
Little Boy
235U Gun-Type Device
Nagasaki
Fat Man
239Pu Implosion Device
11. 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
12. 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
14. 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)
15. Weapon Effects(Based on a 20 kt low-altitude Airblast) Peak shock wave overpressure
~14 psi @ Ľ mile
Thermal energy
~18 cal/cm2 @ 1 mile
Prompt radiation dose
Neutron ~ 0.8 Gy @ 1 mile
g-ray ~ 1.2 Gy @ 1 mile
16. 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
17. Fallout, con’t. Decay rate:
t can be any time unit
Average photon energy ~0.7 MeV
18. 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
19. 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.