1. Nuclear Fusion and Fission

2. Nuclear Fission Division of Nuclei – Splitting of nucleus into smaller fragments when bombarded with neutrons – This is the reaction that takes place in nuclear reactors such as the one in San Onofre

3. Nuclear Fusion The combination or addition of nuclei – The reaction that powers the sun

4. Energy Released: Matter can be changed into energy. E = mc 2 E = energy m = mass c = speed of light

5. The energy released by fusion is three to four times greater than the energy released by fission. Why? The amount of mass transformed into energy is that much greater in a fusion reaction than in a fission reaction. E = mc 2

6. Nuclear Force The nucleus is held together by the strong nuclear force. The strong nuclear force acts between: – protons – neutrons – protons and neutrons

7. Nuclear Force Has a limited range comparable to the size of an atomic nucleus. Able to overcome the mutual electrostatic repulsion of the protons only when the protons and neutrons are near each other as they are in the nucleus of an atom.

8. Fission Bombs Fission bomb : assemble a supercritical mass of fissile material, and a chain reaction will rapidly produce neutrons that, in turn, generate more fission and neutrons. The challenge is to bring two subcritical masses together quickly before the energy released by the initial fission blows the masses apart and stops the chain reaction. The physicists had to answer two fundamental questions: how much fissile material would be required for the weapons, and how much time would be needed for an effective detonation.

9. Fusion Bombs H-Bombs – Rely on the fusion of the isotopes of hydrogen

10. Radiation in Your Life 3 methods of Identifying Radiation: – Geiger Counter: Detects Beta radiation – Scintillation counter: Detects all types of radiation – Film Badge: Layers of photographic film that can be developed to determine strength and type of radiation

11. Applications of radioisotopes in research and medicine Tracers – Used to study chemical reaction mechanisms – Test effects in agriculture Diagnose diseases (Iodine – thyroid problems) Treatment of cancer

12. The End