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Nuclear Reactions

Learn about nuclear fission, fusion, chain reactions, reactors, and energy production in this detailed guide. Discover the science behind nuclear transmutations and the operation of nuclear reactors. Explore the benefits and challenges of nuclear energy utilization.

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Nuclear Reactions

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  1. Nuclear Reactions ChemistryMrs. Coyle

  2. Part I • Fission and Fusion

  3. Transmutations • When a nucleus of an element is transformed to a nucleus of another element.

  4. Transmutations • Can occur through: • Decay (Spontaneously) • Nuclear Reactions (Fusion and Fission)

  5. Nuclear Reactions • Fission • Fusion

  6. Nuclear Fission • Enrico Fermi (USA) 1930’s • Lise Meitner, Strassman, Hahn (Germany) • Bombarding neutrons at 235U or 239Pu causes fission (splitting) of the nucleus producing new neutrons that then cause more fission in a chain reaction. • Huge amounts of energy (mostly kinetic energy of fragments) is released

  7. Nuclear Fission Chain Reaction Neutron bombardment n + 235U  236U X+Y +n + energy

  8. Nuclear Fission • 235U is a rather rare isotope(0.7%) of the more abundant 238U which does not undergo fission. • Nuclear Bomb • Nuclear Power Plants

  9. Nuclear Fusion • Sun’s energy comes from fusing of hydrogen to form helium • Product has higher mass number than reactant

  10. H + H  He +n + energy

  11. Part II • Nuclear Energy

  12. E=mc • Mass – Energy Equivalence • Special Relativity

  13. Nuclear Energy used to make Electricity • 16% of the world's electricity is produced from nuclear energy . • In the US 20% of electricity is made by about 130 nuclear reactor sites.

  14. Nuclear Reactor at Indian Point, NY

  15. Main Parts of a Nuclear Reactor • Fuel Rods • Neutron Moderator • Control rods • Coolant • Containment

  16. Fuel Rods • Pellets of uranium oxide arranged in tubes in the reactor core. (Plutonium is also sometimes used as fuel). • About 260 fuel rods form an assembly.

  17. Neutron Moderator • Slows down the neutrons released from fission so that they are captured by the fuel to continue the chain reaction. • Water or graphite.

  18. Control Rods • Neutron-absorbing material such as cadmium, hafnium or boron, and are inserted or withdrawn from the core to control the rate of reaction, or to halt it.

  19. Coolant • A liquid or gas circulating through the core so as to transfer the heat from it.

  20. Steam Generator • The heat from the reactor is used to make steam to run the turbine to generate electricity.

  21. Containment • A one meter thick concrete and steel structure around the reactor core. • Protects the core. • Protects the environment from radiation in case of malfunction.

  22. Refueling • Every 1-2 years fuel rods are replaced. • Spent fuel rods are still radioactive (nuclear waste).

  23. Nuclear Reactors

  24. Part III • Detecting radiation

  25. The Geiger Counter • Radiation detector • Hans Geiger

  26. Operation of Geiger Counter • The radiation ionizes a gas (argon) and frees electrons. • The electrons are attracted to the positive electrode, that ionize gas again etc, producing a current pulse. • This is amplified and heard as a sound.

  27. Units of Radiation • measured in rads (radiation absorbed dose), a unit of absorbed energy • 1 rad = 0.01 joule of radiant energy absorbed/kilogram of tissue • 1 rem (roentgen equivalent man) is the radiation dosage based on potential damage

  28. Cosmic Rays • Cosmic rays are of two types: • high-energy particles. • high-frequency electromagnetic radiation (gamma rays). • They affect us indirectly by transforming nitrogen atoms in the air to radioactive carbon-14, which ends up in plants we consume.

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