How do Nuclear Power Plants Work?
Nuclear power plants run on radioactive materials such as Uranium and Plutonium that is mined from the ground. To be usable in a power plant the radioactive material must be highly concentrated when it is mined. Power plants use either Uranium-235 or Uranium-238 that is processed into Plutonium. After the uranium is processed it is transformed into Uranium-308 which is the form of uranium used for fuel. Most of the U.S. uranium comes from foreign countries such as Russia and Canada. There are 100 currently operating power plants in the United States.
The Process:
The Process:
- Uranium atoms are bombarded by neutrons which results in those atoms splitting apart and creating large amounts of energy (nuclear fission)
- The Uranium is transformed into pellets which are then pushed together to create long fuel rods.
- Those fuel rods are put into water or another substance that can safely be used as a coolant such as carbon dioxide
- The heat from the uranium causes the coolant to heat to 520 degrees
- This heat produces energy that makes a turbine spin a generator
- The coolant also contain control rods that determine the amount of heat produced and reaction rate, while also assuring that the uranium does not melt or over heat
- All of this is housed in a containment structure made up of thick walls of steel and concrete to keep the radiation out of the environment.
Boiling Water Reactor (GIF) | |
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Pressurized Water Reactor (GIF) | |
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Definitions (Courtesy of Duke Energy)
- Cooling tower: A hollow structure in which water from the plant's condenser is cooled, releasing its heat through water evaporating into the air. The emission from a cooling tower is simple water vapor, similar to a rain cloud.
- Control rods: Control rods are made of a material that absorbs neutrons. They can be manipulated into and out of the core to act as on/off switches for the fission chain reaction. When the control rods are raised, fission increases and more heat is produced; when lowered, the chain reaction slows down. The reactor can be quickly shut down by rapid insertion of the control rods into the reactor core.
- Potassium iodide: Potassium iodide (also called by its name as an element, KI) is an over-the-counter drug (a simple salt) that may reduce the amount of radioactive iodine absorbed by your body's thyroid gland. KI fills your thyroid with iodine so that it cannot absorb any radioactive iodine. In North Carolina, local health departments distribute KI to residents within a 10-mile radius of nuclear plants for use in case of an emergency.
- The fuel rod: Most fission products remain bound inside the ceramic uranium pellets. These pellets are stacked and sealed inside fuel rods made of zirconium alloy. The fuel rods are joined together into fuel assemblies. The zirconium alloy coating provides the first of three radiation protective barriers.
- The reactor coolant system: The heat generated by the fuel is removed by the reactor coolant system, which circulates through the fuel assemblies. The reactor coolant system is totally enclosed and provides the second of the three radiation protective barriers.
- The containment building: The reactor coolant system is totally enclosed in this building. This massive building is an air-tight, cylindrical concrete building with 4-1⁄2-foot concrete walls reinforced with steel, a dome 2-1⁄2 feet thick and a base 12 feet thick. This is the third radiation protective barrier.
- Turbine: An engine in which a wheel of curved vanes (blades) is attached to the driving shaft. The pressure of steam, water, or air against the vanes causes the shaft to turn.
- Watt: A unit of power used to specify the rate at which electrical energy is dissipated. One kilowatt equals 1,000 watts; 1 megawatt equals 1 million watts, or 1,000 kilowatts.