The control rods absorb neutrons; they look like sleeves. Lowering them over the fuel rods prevents the neutrons from one fuel rod reaching the next rod, and so they control the rate of the reaction. Lowering them completely causes the reaction to stop. A heat exchanger is a device that allows heat from the hot radioactive coolant to pass to another series of pipes containing water without having to mix together. This turns the water into steam which then goes on to power a turbine. Environmental impact of fission reactors Positive: No CO2 emissions, no greenhouse gases. Negative: Radioactive waste, potential for major accidents. Nuclear Fusion* is the combining of two small nuclei to form one large nucleus with the release of energy. Nuclear Fusion Example = deuterium (one proton plus one neutron) = tritium (one proton plus two neutrons) Both nuclei are hydrogen because it is the number of protons that determines the identity of the element, and both of these have one proton. Note that this involves the combination of 2 positively charged particles. To overcome this a large amount of energy must be supplied. Coulombic repulsion (remember Coulomb’s Law?) Why is a fission reactor a more viable source of energy than a fusion reactor? Easier to initiate reaction Fission can be more easily controlled Advantage of Fusion over Fission: Less radioactive waste. Deuterium is readily available from the oceans. No dangerous chain reactions. have fusion reactors producing electricity for us now (instead of fission reactors)? So why don’t we There is, as of yet, no way to maintain and control the high temperatures required for fusion reactors. There are a couple of prototypes, e.g. ITER in France, but all are a long way from becoming commercial. The energy we get from the sun comes from nuclear fusion reactions in the sun* Leaving Cert Physics Syllabus Content Depth of Treatment Activities STS Nuclear Energy Principles of fission and Interpretation of nuclear Fusion: source of Sun’s fusion. reactions energy. Nuclear weapons. Mass as a form of energy. Appropriate calculations Mass transformed to other Mass-energy conservation forms of energy in the Sun. in nuclear reactions. E = mc2 Nuclear reactor (fuel, Audiovisual resource Environmental impact of moderator, control rods, material fission reactors. shielding, and heat Development of fusion exchanger). reactors. Disposal of nuclear waste.
The control rods absorb neutrons; they look like sleeves. Lowering them over the fuel rods prevents the neutrons from one fuel rod reaching the next rod, and so they control the rate of the reaction. Lowering them completely causes the reaction to stop. A heat exchanger is a device that allows heat from the hot radioactive coolant to pass to another series of pipes containing water without having to mix together. This turns the water into steam which then goes on to power a turbine. Environmental impact of fission reactors Positive: No CO2 emissions, no greenhouse gases. Negative: Radioactive waste, potential for major accidents. Nuclear Fusion* Nuclear Fusion is the combining of two small nuclei to form one large nucleus with the release of energy. Example = deuterium (one proton plus one neutron) = tritium (one proton plus two neutrons) Both nuclei are hydrogen because it is the number of protons that determines the identity of the element, and both of these have one proton. Note that this involves the combination of 2 positively charged particles. To overcome this Coulombic repulsion (remember Coulomb’s Law?) a large amount of energy must be supplied. Why is a fission reactor a more viable source of energy than a fusion reactor? Easier to initiate reaction Fission can be more easily controlled Advantage of Fusion over Fission: Less radioactive waste. Deuterium is readily available from the oceans. No dangerous chain reactions. So why don’t we have fusion reactors producing electricity for us now (instead of fission reactors)? There is, as of yet, no way to maintain and control the high temperatures required for fusion reactors. There are a couple of prototypes, e.g. ITER in France, but all are a long way from becoming commercial. The energy we get from the sun comes from nuclear fusion reactions in the sun* Leaving Cert Physics Syllabus Content Depth of Treatment Activities STS Nuclear Energy Principles of fission and fusion. Interpretation of nuclear reactions Fusion: source of Sun’s energy. Nuclear weapons. Mass as a form of energy. Mass-energy conservation in nuclear reactions. Appropriate calculations Mass transformed to other forms of energy in the Sun. E = mc2 Nuclear reactor (fuel, moderator, control rods, shielding, and heat exchanger). Audiovisual resource material Environmental impact of fission reactors. Development of fusion reactors. Disposal of nuclear waste.
31.%20Fission,%20Fusion%20and%20Nuclear%20Energy.docx