The Development,
Decision, and Reaction
Albert Einstein writes letter to
FDR
Telling him about the possibility
of an atomic bomb AND
That Germany might be working
on one
Special Theory of Relativity
(E=mc²)
Mass can be converted to Energy
where “c” is the speed of light
A small amount of mass can create
a huge amount of energy
Code name for the project to develop the Atomic Bomb
Named for site of Columbia University where much of early
research done
125,000 workers
2.2 Billion dollars
Complete secrecy
Most did not know
the ultimate
purpose of their
work until news of
Hiroshima bombing
Leo Szilard
Fled Germany in 1933
Conducted 1st controlled nuclear
reaction
Created 1st Nuclear Reactor w/
Enrico Fermi
J. Robert Oppenheimer
Headed Los Alamos Laboratory
Helped to direct 1st test of atomic
bomb
Maj. Gen. Leslie Groves
Director of Manhattan Project
Credited with success of it
Fission – the splitting of an atomic nucleus resulting
in the release of large amounts of energy
Energy Released
from Each Fission
200 MeV
(million electron volts)
Includes gamma
radiation (deadly)
http://www.atomicarchive.com/Fission/FissionMov1.shtml
Chain Reaction – Process in
which neutrons released in
fission produce an
additional fission
http://www.atomicarchive.com/Movies/Movie1.shtml
Time of Reaction –
Released neutron travels at
speed of 10 million meters
per second
Complete Process of a bomb
explosion is a microsecond
(1 millionth of a second)
Critical Mass
The point at which the chain
reaction becomes self
sustaining.
Manufacturing &
Separating Isotopes
Necessary
U235 – only 0.7% of
uranium
P239 – not naturally
occurring, had to be
made
Creating & Controlling
Chain Reaction / Bomb
Design
How do you set it off
without blowing
yourself up?
The will work but are
they safe?
Uranium Bomb
220 lbs
Simpler – More Fissionable
900lbs total
Gun - Type
http://www.atomicarchive.com/Movies/Movie9.shtml
Plutonium Bomb
More Complicated Process
Implosion started chain reaction
Stronger of the two bombs
http://www.atomicarchive.com/Movies/Movie3.shtml
Alamogordo, New Mexico
Plutonium Bomb
July 16, 1945 – 1st
Successful Test of Atomic
Bomb
Explosion larger than
expected
Equivalent to 20,000 tons of
TNT
Shock felt 160 miles away
broke windows 120 miles
away
http://www.atomicarchive.com/Movies/mushroomcloud.shtml
Vaporization point
(1/2 mile – 98% fatalities, 3000 - 4000C)
Total destruction zone
(1 mile – 90% fatalities, all buildings destroyed)
Severe blast damage area
(1.75 miles – 65% fatalities, 35% injuries – larger structures collapsed,
bridges & roads damaged)
Severe heat damage
(2.5 miles – 50% fatalities, 45% injuries – everything some kind of
burn, people killed from suffocation – Oxygen used by fire)
Severe fire and wind damage
(3 miles – 15% fatalities, 50% injuries – home & buildings damaged,
people blown around, 2nd degree burns, if they survived)
Ground Zero (hypocenter)
Point on earth directly
under point of detonation
Thermal Effects
Radiation = Heat
Travels at speed of light
Visible Light –
“flash blindness” – lasts
several minutes
Skin Burns (2nd & 3rd Degree)
10,000 severe burn cases
Can cause fires in homes
& buildings
Thermal Pulse
http://www.atomicarchive.com/Effects/thermalpulse.shtml
Blast Effects
Causes most damage
Shockwave of air can
crush & knockdown
objects
Large buildings
destroyed by change
in air pressure
People & Objects
destroyed by wind
Destruction can lead
to fires
http://www.atomicarchive.com/Effects/blastwave.shtml
Nuclear Radiation
Initial – radiation that
arrives during 1st minute
Strongest near ground
zero – few die from it
Why?
Residual – From
radioactive fallout
Fallout
Radiation received from
radioactive particles
that are distributed at
varying distances
Carried by wind and
rain
Long Term Effects
Radiation Effects on
Blood Disorders
Humans
Cataracts
Hair Loss
Malignant Tumors
Brain – seizures,
immediate death (Cancers)
Keloids
Increased susceptibility to
infection
Increased risk for
leukemia & lymphoma
Heart failure & death
Bloody vomiting, diarrhea
Sometimes sterility