NIS – PHYSICAL SCIENCE

Lecture 68 – Lecture 69Nuclear Energy

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Nuclear ReactionsSome elements can undergo nuclear reactions, which results in different elements.Nuclear Fission and Nuclear FusionNuclear Fission:In nuclear fission reactions, the nucleus of a heavy element splits into smaller nuclei, releasing energy.Example: U-235

Nuclear Fusion:In nuclear fusion reactions, the nuclei of small elements fuse to form a heavier nucleus.Example: 4H He + Energy

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Nuclear ReactionsThe amount of energy released can be calculated by Einstein’s famous formula:

E = m*c2 Calculate the amount of energy released by converting 1 kg of U-235 into energy.The energy released in nuclear reactions is in the form of light.This energy can be converted into thermal energy to generate electricity.

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Nuclear Power PlantsA nuclear reactor uses the energy from controlled nuclear reactions (nuclear fission) to generate electricity.Why not nuclear fusion?Nuclear reactors use U-235 as nuclear fuel.The reactor core contains uranium dioxide fuel in the form of tiny pellets placed in rods fuel rod bundleCheck out Figure 12 and Figure 13!!Why are there control rods in the reactor core?

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Nuclear Power Plants

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Nuclear Power Plants

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Nuclear Power PlantsWhat are the advantages of using nuclear energy compared to fossil fuels?Although nuclear power plants do not pollute the environment as much as the fossil fuels, there are some risks of using nuclear energy:

Environmental damage due to hot waterThe release of radioactivity (Chernobyl)The disposal of nuclear waste

Nuclear waste is any radioactive by-product that results when radioactive materials are used.Nuclear wastes are classified as low-level waste and high-level waste.