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Nuclear Energy

Nuclear Energy. ATOM. ATOM. LARGE ATOM. LARGE ATOM. LARGE ATOM. ENERGY. ENERGY. ATOM. ATOM. Using Nuclear Energy. Nuclear energy is released in two ways:. Fusion Energy is released when two or more nuclei are fused together to form a larger nucleus. Fission

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Nuclear Energy

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  1. Nuclear Energy

  2. ATOM ATOM LARGE ATOM LARGE ATOM LARGE ATOM ENERGY ENERGY ATOM ATOM Using Nuclear Energy Nuclear energy is released in two ways: Fusion Energy is released when two or more nuclei are fused together to form a larger nucleus. Fission Energy is released when two or more nuclei are produced from a larger nucleus. ENERGY

  3. Atoms, Elements, Isotopes • All matter is made up of atoms. • Atoms contain: • Protons • Neutrons • Electrons

  4. Radiation • An element is radioactive if its nucleus is unstable • An unstable nucleus changes spontaneously by radioactive decay

  5. Radiation • There are many types of radioactivity, you should be aware of at least three: • α-decay: emitting an alpha particle (He4 nucleus) • β-decay: emitting a beta particle (electron or positron) • γ radiation: emitting gamma rays (high energy electromagnetic radiation)

  6. Radioactive Decay Chains • When an element decays, the original nucleus, called the parent, changes into a new element, called the daughter. • If the daughter element is also unstable, it in turn will decay. • This process continues until a stable nucleus is reached.

  7. E = mc2 • In radioactive decay, the sum of the masses of the decay products is less than the mass of the parent nucleus

  8. Exponential Decay • Radioactive decay occurs spontaneously. • Each decay event is independent. • The rate of decay is proportional to the number of nuclei present: N = Noe-λt

  9. N = Noe-λt • This equation provides the calculation of the half-life, t1/2 , of the radioactive material.

  10. Some half-lives of interest: • U-238 t1/2= 4.5 x 109 years • U-235 t1/2= 7.1 x 108 years • Pu-239 t1/2= 24,000 years • C-14 t1/2= 5,730 years • Co-60 t1/2= 7.3 years

  11. Background Radiation • Radiation is all around us, all the time. • Cosmic rays • Thermal radiation • Decaying matter • Radon

  12. The Fission Reaction • Fission is the result of a reaction between the nucleus of a heavy element and a free neutron. • The heavy nucleus absorbs the neutron splits into two fission products, energy is released, and two or three free neutrons are ejected.

  13. Fission Chain Reaction • The free neutrons can go on to collide with more heavy nuclei to create more fission reactions. • This results in the release of great amounts of heat, radiation, and neutrons. • This is called a chain reaction.

  14. The Mousetrap Model • One model of an uncontrolled nuclear chain reaction is the mousetrap model.

  15. Nuclear vs. Chemical Binding • The energy released from the fissioning of a gram of uranium releases millions of times more energy than burning a gram of coal. • Fission of a uranium atom: ~200 MeV • Chemical burning a carbon atom: ~3 eV

  16. BE = ΔE=Δmc2 • The difference between the original and final masses is exactly the energy released during fission, as calculated by E=mc2.

  17. Curve of Binding Energy

  18. Nuclear Fusion • As we know, commercial nuclear power is a result of nuclear fission. • There is another nuclear reaction, fusion, that also holds great potential for power generation.

  19. Fusion • For proof of this, we need only look to the stars: giant fusion reactors that have producing power for billions of years.

  20. Fusion • The fusion reaction is the opposite of fission: • two small nuclei (in this diagram, H-3 and H-2) combine to make a new, heavier nucleus (He-4) • a great deal of energy is released

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