| Nuclear
Reactions Induced Radioactivity Fission Fusion Nuclear Weapons Nuclear Power --------------------------------------- Joseph F. Alward, PhD Department of Physics University of the Pacific |
 "I am become Death, the shatterer of worlds."--Shiva in "The Bhagavad Gita".
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 Hindu god Shiva |
Units of Absorbed Radiation
| Rad: 10 milli-joules per
kilogram 20 rads of X-rays doesn't do the same damage to humans as 20 rads of alpha particles. ---------------------------------------------- Rem: an absolute biological damage unit |
Radiation Sickness
| Dose (rems) |
Effect |
| 50-300 | Sickness |
| 400-500 | Lethal 50% (LD50) |
| Above 600 | Lethal 100% (LD100) |
Calculate Rems from Rads
(Relative Biological Effectiveness)
|
|
Radon Poisoning
 |
Uranium in earth's crust decays to radium, which decays to radon. Radon is an odorless, tasteless, lighter-than-air gas which rises from the ground through cracks and fissures in the earth into homes.
When breathed, the alpha- |
Carbon-14 Production
 Neutron enters nucleus and kicks out a proton. 0n1 + 7N14 ---------> 6C14 + 1p1 |
Neutron Bombardment
 "Saint Rosalie Interceding for the Plague-Stricken of Palermo", (Anthony Van Dyke) |
Neutron bombardment reveals absence of beta-emitting manganese, once commonly found in the brown pigment umber.
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Transmuting Uranium to Neptunium
 Neutron enters nucleus and is transformed into a proton and an electron (which leaves the nucleus). |
Nuclear Fission
 |
Average number of neutrons released is 2.5.
Combined kinetic energy of
C + O2 => CO2 |
Estimating Energy Released During Fission
 |
About 7.5 MeV to about 8.5 MeV per nucleon.
Mass difference |
Chain Reaction
(Slow neutrons cause fission)
 |
Slow neutrons are required. --------------------------------------- A chain reaction occurs if more than one neutron goes on to cause another fission. --------------------------------------- Neutrons can be slowed by bouncing them off of small objects, such as carbon nuclei. --------------------------------------- One pound of U-235, if completely fissioned, yields the same energy as 100,000,000 pounds of coal. |
Cadmium Control Rods Absorb Neutrons
 Enrico Fermi supervised construction of the world's first nuclear reactor. |
 Cadmium is a good absorber of neutrons. |
World's First Controlled Nuclear Chain Reaction
 Handball court under the bleachers at the University of Chicago, 1942. Uranium-235 is at the center of the stack of graphite blocks; the carbon acts as a moderator, slowing neutrons. |
The Manhattan Project
 Oak Ridge, Tennessee. 60,000 workers worked for three years to separate 2 kilograms of uranium-235 from uranium-238. |
Trinity Test Site
 5:30 am, July 16, 1945, Alamogordo, New Mexico. |
Dr. Robert J. Oppenheimer and Maj. Gen. Leslie L. Groves |
The First Atomic Bomb Dropped in Anger
 "Little Boy", two feet in diameter, ten feet long, 9000 pounds, dropped on Hiroshima, Japan, was a uranium bomb. Equivalent to 20,000 tons of explosive. |
Fat Man and Little Boy
 |
Atomic Bomb Targets
 The only nuclear weapons used in anger were the two atomic bombs dropped in 1945. |
The Scorched Remains
 Nagasaki, Japan |
 Nagasaki survivor. Click here for panoramic view of Hiroshima.) |
Atomic Cannon
 Test Site: Frenchman Flat, Nevada, May 25, 1953. Equivalent to 15,000 tons of TNT. Height of blast: 524 feet. History of the Bomb |
Atomic Blast
(Before playing, turn off CD player and turn
up volume to maximum.)
The Reactor Vessel
 |
The water in the reactor vessel has three purposes.
The water, being composed of
Water also acts to remove heat |
A Nuclear Reactor
 |
Heat generated by fission in uranium rods creates steam which turns turbine blades connected to a coil of wire in magnetic field. |
Nuclear Power in Germany
 |
The China Syndrome
 What would happen if the water was lost? |
Discoverer of Nucleus Was Wrong about Nuclear Power
 |
 Rutherford at 1911 Solvay Conference |
Fusion
 Fusion is the opposite of fission. Deuterium must be moving extremely fast to fuse. |
Fusion in Stars
 10 million degrees at the core causes fusion of hydrogen into helium. |
Fission versus Fusion
 When uranium splits, energy is released. When two deuterium nuclei smash together to form helium, energy is released. --------------------------------------------------------------------------------------------------------------------------------- In fusion and fission the mass of the products is less than the mass of the reactants; the "lost" mass is transformed into energy. |
The Binding Energy Graph
 The greater the binding energy per nucleon, the smaller is the mass per nucleon. |
Deuterium-Tritium Fusion
 |
Neutrons carry away 80 % of the energy released (recall the M/m ratio calculation in the Nuclear Physics electure)
Neutron energy is about |
Fusion Reactor
NOVA Laser Facility, Lawrence
Plastic target shells to contain |
Deuterium-Tritium Fusion
 |
Laser evaporates D-T, creating a "plasma" of charged particles which push away from one another. The reaction force compresses and heats core. |
The Neutron Bomb
China
Has Neutron Bomb