Heat to Electricity

Standard Electric Power Plant

About half of the electricity produced in Illinois comes from burning coal in coal-fired power plants. The other half comes from nuclear power plants. Below is a diagram for a convention power plant. Some type of fuel (usually coal but also petroleum or natural gas) is use to heat water into steam. The pressure from the steam moves a turbine that is connected to a generator unit. The generator converts the motion of the turbine into electric energy that can be carried through power lines to the consumers. The steam is condensed and returns to the boiler.

Nuclear Electric Power Plant

Instead of burning a fossil fuel, water or other heat transfer fluid is heated by the energy given off by nuclear fission of uranium-236. The diagram below shows a pressurized water reactor. Note that the water that cools the reactor core is used to heat other water that actually drives the turbine. The water coolant is sealed so that radioactive material can't go outside the reactor core.

Because of radiation given off in the fission reactions, the reactor core is completely contained and separate from the electric generation part of the plant.

There are some parts of the plant that are unique to a nuclear power plant.
  1. Fuel Rods
      The fuel rods consist of zirconium-encased pellets of UO2 with 3-5 % uranium-235 in uranium-238.

  2. Moderator
      This is a substance that can slow the neutrons produced in fission so that these can be absorbed by the other nuclei and support the chain reaction. Water is the moderator in most reactors.

  3. Control Rods
      These are substances that absorb neutrons and can control (or stop) the fission reaction. Boron and cadmium are typical substances that absorb neutrons in these control rods. The rods can be moved into the reactor core as needed. Control rods can inserted or withdrawn. For a boron-containing control rod, the reaction with neutrons is:

Go back to the model fission reaction. Choose the nuclear reactor and observe the changes as you raise and lower the control rods.

US Use of Nuclear Power

There are currently 104 operable commercial nuclear reactors at 65 nuclear power plants in the United States. We have more nuclear power capacity than any other country and, on average, 20 % of the electricity in the country (nearly 50 % in Illinois) comes from nuclear power. Between 1985 and 1996, 34 new reactors were placed in service.

Clinton Power Plant

The Clinton Nuclear Power Plant is located near Clinton, Illinois is the closest one to the University of Illinois campus. It has a General Electric boiling water reactor on Clinton Lake. The power station began service on April 24, 1987.

Professor Patricia Shapley, University of Illinois, 2011