the nucleus and nuclear reactions. nuclear descriptions atomic number atomic mass number isotopes...
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THE NUCLEUS AND NUCLEAR REACTIONS
Nuclear descriptionsAtomic numberAtomic mass numberIsotopesnucleons
Nuclear forcesElectromagnetic forceStrong force
Nuclear reactions and decayDecay types and nuclear stabilityAlphaBetaGammaNuclear equations & Conservation lawsHalf life & Activity and probability
Nuclear reactions and decayFission Vs fusionTable of electromagnetic & strong force work or energy values Vs nucleus sizesBinding energy Vs. mass numberBinding energy Vs. mass defect
Nuclear reactorsFission reactorsChain reactionModeratorControl rodsTypical reactor designContainment structure and primary loopSecondary loop and electrical energy
Nuclear reactorsFusion reactors & Reaction confinement
The atomic number is the number of protons in the nucleus of the atom, this number determines the identity or element of the atomThe atomic mass number is the total number of neutrons and protons in the nucleus of the atomIsotopes are atoms of the same element (same number of protons), but with differing numbers of neutrons. Isotopes are expressed as the element symbol with a preceeding superscript for the mass number and preceeding subscript for the charge.Nucleon is a general term used to describe either a proton or neutron (large nuclear particle).The electromagnetic force acts between all charged particles. In the nucleus the electromagnetic forces acts between the protons tending to cause the nucleus to fly apart.The strong force is an attractive force that acts between all nucleons. The strong force is extremely large, but is very short range, not even extending the full diameter of large nuclei.Decay types are named for the type of particle &/or radiation emitted during that particular decay. Radioactive decays occur when the arrangement of neutrons and protons, or the neutron to proton ratio yields an unbalanced (unstable or high energy) nucleus. (Boulder on cliff analogy). For the nucleus to lose energy and become stable it must emit either a matter particle or a photon (energy particle) which carries away the excess energy and leaves the nucleus with a more stable ratio or arrangement of neutrons and protons.Alpha decay occurs when the ratio of neutrons to protons is unbalanced and losing the a helium nucleus yields a more stable parent nucleus.Beta decay also occurs when the neutron to proton ratio is unbalanced, but in this case the loss of an electron or positron changes a neutron into a proton or proton into a neutron.Gamma decay occurs when the neutrons and protons are in an unstable arrangement in the nucleus. A gamma photon is emitted when the nucleons rearrange into a more stable pattern. Nuclear equations must maintain conservation of mass and charge so the total number of nucleons must be the same on either side of the yield sign and the total charge must be the same on either of the yield sign.Half life is the time required for half a sample of radioactive material to undergo decay. Activity is the rate at which decays occur. Both the half life and the activity are probability functions NOT certainties.Fission is the process of starting with a large nucleus and breaking it down into at least two smaller nuclei.Fusion is the process of starting with at least two small nuclei and putting them together to form one large nucleus.Since the strong force is so short range it can only contribute more energy per nucleon than the electromagnetic force when the nucleus is small.The difference between the work done by the strong force and the work done by the electromagnetic force is the binding energy. The changes in energy during fission and fusion can also be expressed and measured as mass changes based on Einsteins famous e=mc^2 equation.This is why fusion of small nuclei yields energy, AND fission of large nuclei yields energy. This difference is clearly displayed in the binding energy Vs. mass number graphNuclear reactors are used to collect the energy released by nuclear fission.A chain reaction occurs when the products of a nuclear decay create additional unstable nuclei which then fission and the products of this fission continue the process.The moderator acts to slow down the high energy fast neutrons emitted from a nucleus, to create thermal neutrons which can be captured by another nucleus and start a new fission event.Control rods capture neutrons and act to slow down the reaction. Graphite (carbon) is typical control rod material.The reactor core and all materials which come in direct contact with nuclear reaction reactants and products stay in the containment structure at all times.The secondary loop is used to produce steam for electrical energy production.