How much energy

1
How much energy

• 200 MeV is released per fission event
• The fission of 1 g of uranium or plutonium per
  day liberates about 1 MW.
• This is the energy equivalent of 3 tons of coal
  or about 600 gallons of fuel oil per day
• No CO2 emissions!
• Vastly superior in terms of energy per amount of
  fuel

2
Self sustaining or chain reaction

• The fission reaction itself releases neutrons,
  these can be used to fission additional nuclei,
  so the elements are there for a sustained or
  chain reaction.
• Tremendous power capability made this an ideal
  weapon.

3
Fission Bombs

• Created in response to a fear that Nazi Germany
  would develop one first, which would tip the
  balance of power and possibly the outcome of WWII
  in their favor.
• Manhattan Project Secret US project to develop
  a nuclear weapon
• Developed 3 nuclear devices, one with 235U and
  two with 239PU.
• One was tested in New Mexico in 1945, the other
  two were dropped on Hiroshima and Nagasaki Japan
  in August 1945, ending WWII in the Pacific.

4
Critical Mass

• In order to sustain a chain reaction, one needs a
  specific amount of fissionable material, called
  the critical mass
• Critical mass is the smallest amount of fissile
  material needed for a sustained nuclear chain
  reaction.
• Creating the critical mass was one of the
  challenges that faced the Manhattan project

5
The devices

• Fat Man and Little Boy
• Little Boy device dropped on Hiroshima
• Gun-type device
• One mass of U-235, the "bullet," is fired down a
  gun barrel into another mass of U-235, rapidly
  creating the critical mass of U-235, resulting in
  an explosion.

6
The devices

• Fat Man
• Tested in New Mexico and dropped on Nagasaki
• Used Plutonium rather than Uranium
• Implosion style device
• The required implosion was achieved
• by using shaped charges with
• many explosive lenses to produce
• the perfectly spherical explosive
• wave which compressed the
• plutonium sphere.

7
Effects of a Fission explosion

• Blast Damage
• Thermal radiation
• Electromagnetic Pulse
• Ionizing radiation
• earthquake

8
Blast Damage

• 40-50 of the total energy released is in the
  blast.
• Most of the destruction due to blast effects
• Blast wind may exceed 1000 km/h.

9
Thermal Radiation

• 35-45 of the energy released is in thermal
  radiation
• Burns occur
• Eye injures
• Flash Blindness-caused by the initial bright
  flash, can last up to 40 minutes
• Retinal burns scarring due to the direct
  concentration of explosions thermal energy on the
  eye-rare the fireball needs to be in the direct
  line of sight
• Firestorms-gale force winds that blow in from all
  sides towards the center of a fire

10
Electromagnetic pulse

• The nuclear explosion produced high energy
  electromagnetic radiation-Gamma rays.
• The Gamma rays interact with (scatter) electrons
  and produce higher energy electrons.
• Long metal objects (cables, etc) act as antenna
  and generate high voltages and currents, which
  can damage or destroy electrical equipment.
• No known biological effects, though useful
  against Sentinels (The Matrix).

11
Ionizing radiation

• About 5 of the energy
• In the form of neutrons, gamma rays, alpha
  particles and electrons, moving at nearly the
  speed of light
• Neutrons transmutate (change the atomic structure
  of) the surrounding matter, often making it
  radioactive. This adds to the radioactive fallout

12
What does this have to do with Nuclear Energy

• It sets the historical context and shows the
  power released
• To point out that this is NOT what will happen if
  there is an accident in a nuclear power
  facility-they do not blow up like explosive
  nuclear devices. More on that later