An Introduction to

1. An Introduction to Nuclear Energy

2. Cheap power Virtually unlimited Safe Very little waste produced Nuclear power provides peaceful use for Uranium, Tritium and other reactant substances Nuclear weapons Radioactivity Nuclear waste is toxic for centuries and not easily disposed of The Awesome Power of the Atom Benefits Drawbacks

3. Nuclear Fission • Earth’s Uranium, formed by stars, is actually in fairly high quantities (approx. equal to amount of Tin and Tungsten) • Large radioactive half-life for certain elements like U-238 (4.46 Gy) means there will sufficient fuel for a long time • Possible to extract Uranium from seawater (however uneconomic unless prices rise severely)

4. History of Nuclear Fission • In the 1930s, Otto Hahn and Fritz Strassman, physicists/chemists, became the first people to induce nuclear fission • Bombarded Uranium and unexpectedly ended up with Barium-141 • Lise Meitner and her nephew Otto Frisch, both physicists, later realized the source of the lighter elements was fission of U-235 • Also realized the potential for a chain reaction

5. Simplistic Model of Nuclear Fission Neutron (with energy of about 1eV) moves toward nucleus of U-235

6. Simplistic Model of Nuclear Fission Neutron collides, destabilizing the nucleus

7. Simplistic Model of Nuclear Fission U-236 nucleus oscillates

8. Simplistic Model of Nuclear Fission U-236 nucleus splits, releasing two new nuclei, an average of 2.4 neutrons, and gamma rays at a total of approx. 200MeV That’s 200,000,000x the input energy!

9. Raw Uranium has a U-235 abundance of 0.7% Enriched Uranium has a U-235 abundance of approx. 3-4% Thermal diffusion Gaseous diffusion Gas centrifuge Zippe Centrifuge Aerodynamic separation Electromagnetic Isotope Separation Laser Separation Chemical Separation Plasma Separation How We Enrich Uranium

11. Gas Centrifuge

12. How We Harness the Energy • Enriched Uranium rods are dipped into a cooling tank • Bombarded with neutrons to initiate the chain reaction • Fission takes place • Controlled fission occurs thanks to “control rods” • Fission creates heat, which transfers to the water • Water pumped through tubes to turbine chambers • Steam produced turns turbines, producing electrical energy

15. Unfortunate Side-Effects • When nuclear energy goes wrong, it can be catastrophic • Chernobyl Incident

16. Sources of Deuterium and Tritium • Deuterium is fairly abundant in nature • 1/5000 Hydrogen atoms in seawater is Deuterium, which makes over 1015 tons world-wide • Tritium must be made in labs through the process 6Li + 1n  4He + 3H + 4.8MeV or a similar process.

17. Hydrogen-Fusion Reactions • Deuterium (one neutron) and Tritium (two neutrons) are brought to sufficient temperature (40 million degrees Kelvin/ 72 million degrees Fahrenheit) to overcome the coulomb barrier • The nuclei collide to form He-5 • He-5 diffuses into He-4 and a neutron, releasing 17.6 MeV of energy He-5

18. Nuclear Fusion – Confinement Methods • Magnetic Confinement • Tokamak machine • toroidal chamber in magnetic coils • Inertial Confinement • Shooting fuel pellet with laser or other beam • Gravitational Confinement • Only stars have enough gravity to confine reaction

20. Problems with Nuclear Fusion • Even though the potential for electrical power is immense, the reaction currently requires more energy than it releases • Difficult to harness the energy • Hopefully, future technology and research will make nuclear fusion more than a dream