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Nuclear Reactions:. AN INTRODUCTION TO FISSION & FUSION. Farley Visitors Center. Introduction. Nuclear reactions deal with interactions between the nuclei of atoms The focus of this presentation are the processes of nuclear fission and nuclear fusion - PowerPoint PPT Presentation


  • Nuclear Reactions:AN INTRODUCTION TO FISSION & FUSIONFarley Visitors Center

  • Nuclear reactions deal with interactions between the nuclei of atomsThe focus of this presentation are the processes of nuclear fission and nuclear fusionBoth fission and fusion processes deal with matter and energyIntroduction

  • Matter and EnergyPrevious studies have taught us that matter and energy cannot be created nor destroyedWe now need to understand that Matter and Energy are two forms of the same thing

  • MassMatter can be changed into EnergyEinsteins formula above tells us how the change occursIn the equation above:E = Energym = Massc = Speed of Light (Universal Constant)EnergyLightSpeedE = mc2

  • E = mc2The equation may be read as follows:Energy (E) is equal to Mass (m) multiplied by the Speed of Light (c) squaredThis tells us that a small amount of mass can be converted into a very large amount of energy because the speed of light (c) is an extremely large numberc = 3.0 x 108 m/s300,000,000 m/s

  • FissionFission may be defined as the process of splitting an atomic nucleus into fission fragmentsThe fission fragments are generally in the form of smaller atomic nuclei and neutronsSufficient neutrons will create a chain reactionLarge amounts of energy are produced by the fission process

  • FissionFissile nuclei are generally heavy atoms with large numbers of nucleonsThe nuclei of such heavy atoms are struck by neutrons initiating the fission processFission occurs due to electrostatic repulsion created by large numbers of protons within the nuclei of heavy atoms

  • A classic example of a fission reaction is that of U-235:U-235 + 1 Neutron 2 Neutrons + Kr-92 + Ba-142 + EnergyIn this example, a stray neutron strikes an atom of U-235. It absorbs the neutron and becomes an unstable atom of U-236. It then undergoes fission. Notice that more neutrons are released in the reaction. These neutrons can strike other U-235 atoms to initiate their fission.Fission

  • Fission Reaction

  • FissionThe fission process is an a natural one as a French researcher found a natural uranium reactor in Gabon, West Africa; it has been estimated to be over 2 billion years oldFission produces large amounts of heat energy and it is this heat that is captured by nuclear power plants to produce electricity

  • Producing Electricity from Fission

  • U.S. Electrical Power Sources

  • Fusion is a nuclear reaction whereby two light atomic nuclei fuse or combine to form a single larger, heavier nucleusThe fusion process generates tremendous amounts of energy; refer back to Einsteins equationFor fusion to occur, a large amount of energy is needed to overcome the electrical charges of the nuclei and fuse them together


  • Fusion and EnergyIron and nickel nuclei have the largest binding energies per nucleon of all nuclei and therefore are the most stable.The fusion of two nuclei lighter than iron or nickel generally releases energy. The fusion of nuclei heavier than them absorbs energy.


  • FusionFusion reactions do not occur naturally on our planet but are the principal type of reaction found in starsThe large masses, densities, and high temperatures of stars provide the initial energies needed to fuel fusion reactionsThe sun fuses hydrogen atoms to produce helium, subatomic particles, and vast amounts of energy

  • Every second, the sun converts 500 million metric tons of hydrogen to helium. Due to the process of fusion, 5 million metric tons of excess material is converted into energy in each second. This means that every year, 157,680,000,000,000 metric tons are converted into energy. THE SUN

  • Cold FusionEfforts are being made to start and sustain a fusion reaction at lower temperatures, in other words with a lower amount of input energy

  • Mass and Energy are two forms of the same thing; neither can be created nor destroyed but mass can be converted into energy (E = mc2)Fission is a nuclear reaction in which a heavy atomic nucleus is split into lighter atomic nucleiFusion is a nuclear reaction in which 2 light atomic nuclei are combined into a single, heavier atomic nucleusReview

  • Review

  • QuizWhich nuclear process produces large amounts of energy?A. FissionB. FusionC. Both fission & fusionD. Neither fission nor fusion

  • QuizFission is the process that _________ atomic nuclei.A. CombinesB. Burns upC. StoresD. Splits

  • QuizMass may be converted into energy.A. TrueB. False

  • QuizThe fission process requires heavy atomic nuclei.A. TrueB. False

  • QuizName a nuclear reaction that occurs within the sun:

  • QuizFission is a natural process that occurs on the planet Earth.A. TrueB. False

  • QuizExplain this equation:

    E = mc2



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