1. Nuclear Fission Motivation Principle Nuclear reactor & Weapon
Statistics

2. Relativistic Energy The famous Einstein relationship for energy
                       
includes both the kinetic energy and rest mass energy for a particle. The kinetic energy of a high speed particle can be calculated from
                                 
The relativistic energy of a particle can also be expressed in terms of its momentum in the expression
                                                          

3. Uranium-235 Fission Energy From Uranium Fission
Form of Energy Released
Amount of Energy Released (MeV)
Kinetic energy of two fission fragments
168
Immediate gamma rays 7
Delayed gamma rays
3-12
Fission neutrons 5
Energy of decay products of fission fragments
...
Gamma rays
Beta particles 8
Neutrons  12
Average total energy released
215 MeV

4.                                                                                                                                                                                         
If at least one neutron from each fission strikes another U-235 nucleus and initiates fission, then the chain reaction is sustained.

5. Control - Weapons or Power?
 In general, the steady production of atomic power requires a slow-neutron-induced fission chain reaction occurring in a mixture or lattice of uranium and moderator, while an atomic bomb requires a fast-neutron-induced fission chain reaction in U-235 or Pu-239, although both slow- and fast-neutron fission may contribute in each case.
The technological gap between producing a controlled chain reaction and using it as a large-scale power source or a explosive is comparable to the gap between the discovery of fire and the manufacture of a steam locomotive.

6. PHWR (Pressurized Heavy Water Reactor)

7. PWR (Pressurized Water Reactor)

8. The atomic bombing of Nagasaki on August 9, 1945

9. Statistics
In 2000, there were 438 commercial nuclear generating units throughout the world, with a total capacity of about 351 gigawatts.
In 2001, there were 104 (69 pressurized water reactors, 35 boiling water reactors) commercial nuclear generating units that are licensed to operate in the United States, producing 32,300 net megawatts (electric), which is approximately 20 percent of the nation's total electric energy consumption. The United States is the world's largest supplier of commercial nuclear power.

11. Water as Moderator
Neutrons from fission have very high speeds and must be slowed greatly by water "moderation" to maintain the chain reaction.
The uranium-235 is enriched to % to allow ordinary water to be the moderator.
                                                                              
Loss or the water coolant kills the chain reaction since the fuel configuration is not "critical" without water moderation.
Even with the moderator, the fuel is not "critical" without the inclusion of the "delayed" neutrons which may be emitted several minutes after the fission.