The Effects of Nuclear The Effects of Nuclear Weapons: Weapons: Terrorist ThreatTerrorist Threat

PurposePurpose

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 Nuclear Weapons vs Radioactive Dispersal Device Radioactive Dispersal Device (RDD or Dirty Bomb)(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 discussionRemaining discussion

The remainder of this presentation describes nuclear weapons

For further information on RDD weapons see:– http://www.bt.cdc.gov/radiation/pdf/dirty

bombs.pdf– http://www.nrc.gov/reading-rm/doc-

collections/fact-sheets/dirty-bombs.pdf

Nuclear Weapons TypesNuclear 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 Energy Equivalents of one Kiloton of TNTKiloton of TNTComplete burn-up (fission) of 56 g

(~2 ounces) of 235U or 239Pu1.15 x 106 kilowatt-hours1.8 x 109 British thermal units14,500 Gallons of Gasoline4/5 the energy produced by the

Hoover Dam in 1 hour

Types of Detonations from a Types of Detonations from a Terrorist ThreatTerrorist ThreatMost 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 Distribution of Energy of an Air Burst below 100,000 ftAir Burst below 100,000 ft

0 10 20 30 40 50 60

PromptRadiaiton

ResidualRadiation

ThermalRadiation

Blast andShock

Blast and Thermal accountfor 85% of the Energy released

Nuclear Weapon Experience Nuclear Weapon Experience Two non-testing detonationsTwo non-testing detonations

Hiroshima – Little Boy– 235U Gun-Type

Device

Nagasaki– Fat Man– 239Pu Implosion

Device

Results of a Nuclear ExplosionResults 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 ExplosionResults 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 BeforeHiroshima BeforeHiroshima After

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

1.2( ) (1)D t D t

D(1) = D at 1 hour (days, etc)

D( ) = D at hours (days, etc)t t

SummarySummary 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

ReferencesReferences 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.