nuclear weapons and terrorism...critical mass chain reactions • when a large enough mass of either...
TRANSCRIPT
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Nuclear Weapons and
Terrorism
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Major killers in Wars
• Assault Rifles (64%)
• Handguns (10%)
• Landmines (10%)
• Hand grenades, Artillery, Mortars (16%)
• Since 1900: 34 million soldiers and 80
million civilians killed in wars world-wide
• 2 Nuclear bombs killed 200,000 total.
M16
Howitzer
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Who has nuclear weapons?
US (1800)
Russia (2700)UK (55.5)
France (91.5)
China(400)
Israel(32)
India(12?)
Pakistan(12?)
Thermonuclear
Fission
N. Korea 24?
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Nuclear warheads and plutonium production around the world
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Fusion Weapons
• Fusion
– Elements lighter than Iron release energy
when combined
– Deuterium, Tritium, Lithium
– Reactions that occur inside Sun
– “H” bombs
• Thermonuclear Reactions
– Heat from reaction increases reaction rate,
so less fuel is needed “efficient” bomb
DD
4He
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• Naturally occurring Uranium must be
enriched to >90% 235U in order to make
fission weapons (or to ~5% for nuclear
power plants)
• Enrichment methods
– Gas centrifuge (now being used in Iran and
found in Iraq after 1st Gulf War)
– Gaseous diffusion (used in USA)
– Electromagnetic isotope separation –
(unexpectedly found in Iraq after 1st Gulf War)
Enriching Uranium
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Critical mass chain
reactions
• When a large enough mass of either 235U or 239Pu is assembled, a self-sustaining chain reaction results after the first fission is produced.
• The minimum (“critical”) mass of fissile material that can sustain a nuclear chain reaction depends on the density, shape, and type of fissile material, as well as the effectiveness of any surrounding material (called a reflector or tamper) at reflecting neutrons back into the fissioning mass.
• Depleted U is often used in the tamper
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The first “A” bombs
• Trinity – Gadget (7/16/45)
– Alamagordo test range in New Mexico
– 20 kTon yield
• Little Boy (8/6/45)
– Hiroshima
– 15 kTon yield
• Fat Man (8/9/45)
– Nagasaki
– 20 kTon yield
Museum display in NM
http://www.fas.org/nuke/hew/Usa/Med/Lbfm.html
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How to make an “A” bomb• Use >90% 235U
• Squeeze and confine evenly
• Reflect neutrons back into 235U
• Use initial explosive device to trigger
Little Boy (Hiroshima 8/6/45)
http://www.pcf.city.hiroshima.jp/peacesite/English/Stage1/1-3/1-3-3E.html
3 m
A-bomb dome
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“Fat Man” style of A-bomb• High explosives are arranged to form an
imploding shock wave which compresses
the fissile material to supercriticality.
Burst of neutrons from generator is timed for moment of maximum compression
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Low Yield Nuclear Weapons Designed to “threaten hard and deeply buried
targets."
• Despite claims to produce less fallout due to
underground explosion, a 5 kTon weapon would
produce considerable quantities of radioactive
dirt
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“Dirty” bombs• Does not involve nuclear explosion
• Spreads radiological materials over a wide area
• Most deaths (<100) would be due to the blast, not to the radioactivity
• “Weapon of mass disruption”
• “Difference between a dirty bomb and a nuclear bomb is the difference between a lightning bug and lightning” – Allison
• Much easier to make, however.
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The “secret” of the H-bomb• At the high temperatures of a fission bomb 80%
or more of the energy exists as soft X-rays
• The X-rays heat a polystyrene channel, causing plasma which can compress and ignite the second (fusion) stage before the expanding (1000 km/sec) primary disrupts it.
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Fusion weapons
Published due to Wen Ho Lee case
http://www.fas.org/sgp/eprint/morland.html
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Why is an atomic bomb so much
worse than a TNT bomb?• Amount of heat and light
energy released is 1000 times
greater
• Explosion is accompanied by
invisible, penetrating and
harmful radiation
• After explosion, radioactive
fallout remains and continues to
damage living things for days
weeks years Ground level view of Hiroshima cloud
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Physical Effects of Nuclear Weapons
• Thermal
– Fireball Firestorms
– Mushroom Cloud
• Initial (prompt) Radiation
– Alpha particles (4He++)
– Beta particles (e+ and e-)
– Gamma-rays (g)
– Neutrons (n)
Trinity
http://nuketesting.enviroweb.org/
Bridge in Hiroshima
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Physical Effects of Nuclear Weapons
• Pressure Blast Wave
– Buildings collapse
• Fallout
– Radioactive fragments which stick
to air particles or dirt that is sucked
up mushroom stem
– 80% falls back down in first day
– 90% falls back down in first week
– 10% lasts weeks years
Nagasaki victim
Hiroshima buildings
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Physical Effects of Nuclear Weapons
• Electromagnetic Pulse
– Strongest for very high bursts
g-rays ionize air electrons
– Electrons create large currents in air
– Currents are picked up by power lines
– Power surges shut down grid, destroy
attached electrical devices
• 1.4 Mton airburst in 1962 knocked out
lights in Hawaii over 1000 miles away
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Electromagnetic Pulse Effects
http://www.heritage.org/library/backgrounder/bg1372.html
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How big are the weapons?
• 1 kTon = 1000 tons = 2,000,000 pounds
of TNT equivalent
• ~2 pounds of 235U 20 kTons
• Today’s warhead is 100-200 kTons
• Largest underground burst: 4.5Mtons
• Largest airburst: 58 Mtons
• Over 1700 known tests since 1945
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Nuclear Non-Proliferation Treaty
• Vertical – development of new weapons by the “Big 5”
• Horizontal – spread of weapons to other countries
• “Haves” agree not to spread weapons, materials or technology to “have-nots” – also, to stop vertical proliferation
• “Have-nots” agree not to try to acquire weapons from the “haves,” and will accept inspection and regulation of “peaceful” nuclear technology by IAEA- this stops horizontal proliferation
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There are currently eight states that we know have successfully detonated nuclear weapons.
• Five are considered to be “nuclear weapons states”, an internationally
recognized status conferred by the Nuclear Non-Proliferation Treaty
(NPT). In order of acquisition of nuclear weapons these are:
– the United States of America
– Russia (formerly the Soviet Union)
– the United Kingdom
– France
– the People’s Republic of China
• Since the formulation of the NPT, three non-signatory states of the
NPT have conducted nuclear tests:
– India
– Pakistan
– North Korea
• In addition to these eight, Israel is believed to be an undeclared nuclear
power
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Who still wants nuclear
weapons?• Iran – Was enriching
• States?
• Terrorist?
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The spread of nuclear weapons from Pakistan
LIBYA
CHECHNYA
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For money?
• Small Crude
bombs by US
standards
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How hard is it to
build an atomic
bomb if you have
the raw materials?
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How easy is it to get plans to build an atomic bomb
once you have the materials? Here are the results of
a Google search on "Atomic Bomb Design"
• Early Los Alamos
implosion model
for the plutonium
bomb
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Soviet nuclear suitcase bomb
Are 84 of some 132 special KGB 1 kton suitcase nuclear weapons
unaccounted for as first claimed by Yeltsin's assistant for national
security affairs, General Alexander Lebed, and then retracted?
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A shipping container is
10 x 10 x 30 ft
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20,000 shipping containers enter US Ports
in 1 day, but only 3 or 4% are inspected
Only two
or three
out of 65
shipping
containers
would be
inspected
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How many atomic bombs can
fit into one shipping container?
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The End