Lesson Four

Lesson Plan Four Teacher: Angela Schneider Course: Physics Grade: 11-12 Topic: Nuclear Energy CLE(s): Describe how changes in the nucleus of an atom during a nuclear reaction (i.e., nuclear decay, fusion, fission) result in emission of radiation). Identify the role of nuclear energy as it serves as a source of energy for the Earth, stars, and human activity (e.g., source of electromagnetic radiation, thermal energy within mantle, nuclear power plants, fuel for stars). Distinguish between renewable and nonrenewable energy resources Identify and describe major scientific and technological challenges to society and their ramifications for public policy (e.g., global warming, limitations to fossil fuels, genetic engineering of plants, space and/or medical research) Objectives: The student will identify the two different types of nuclear power plants discussed. The student will discuss the process of energy generation with nuclear power plants. Materials needed: overhead projector, Franklin’s Core transparency, reactor fuel assembly transparency, turbine transparency, two worksheets for each student, post-discussion questions Introduction: We have been studying radioactivity, as well as, nuclear fusion and nuclear fission. Today we are going to focus on the nuclear power plant, where nuclear energy is produced. Content: Nuclear reactor has four main parts: the uranium fuel assemblies, the control rods, the coolant/moderator, and the pressure valve. The fuel assemblies, control rods, and the coolant/moderator make up the reactor core, which is surrounded by the pressure valve, known as Franklin’s Core. Show Franklin’s Core transparency. To produce the uranium fuel assemblies pellets of uranium are inserted into rods. These rods are then carefully bound into fuel assemblies, each of which contains around 240 rods. The assemblies hold the rods in place so that water can flow between them. Show reactor fuel assembly transparency. The uranium undergoes a nuclear chain reaction, producing heat, which is transferred from the reactor core to the steam generator where it turns the turbine, producing electricity. Show turbine transparency. As you know, the production of nuclear energy also produces large amounts of radiation. Therefore, it is necessary to have a plan in case there is an emergency. The control rods are present to regulate the amount of nuclear energy produced by absorbing neutrons. Thus, fewer neutrons hit the uranium atoms, slowing down the nuclear chain reaction. They are only used when necessary. There are two types of nuclear power plants common in the United States. The boiling water reactor generates electricity the same way that fossil fuels do, without a steam generator. Water inside the boiling water reactor boils inside a pressure valve where a steam-water mixture is produced. When pure water (reactor coolant) moves upward through the core it absorbs heat causing the water to boil and produces steam. When the steam rises to the top of the pressure vessel, water droplets are removed, the steam is sent to the turbine generator to turn the turbine. The pressurized water reactor differs from the BWR in that the steam to run the turbine is produced in a steam generator. Water boils at 212°F or 100°C. As the pressure increases, so does the temperature of the water in the pot. In the PWR plant, a pressurizer unit keeps the water that is flowing through the reactor vessel under very high pressure to prevent it from boiling. The hot water then flows into the steam generator where it is converted to steam. The steam passes through the turbine which produces electricity. About two-thirds of the reactor power plants in the U.S. are of the PWR type. Conclusion: Your assignment today is to answer the post-discussion questions (these will probably require some internet research) and complete the two nuclear power plant worksheets.