Investigation 27A: Controlling a nuclear fission reaction

Essential questionsHow are chain reactions necessary for nuclear power?
How do control rods work in a nuclear reactor?
Nuclear reactions produce the energy that is at the heart of nuclear power. Most nuclear reactors use uranium as the fuel for the reactions. When a uranium nucleus is struck by a neutron, the nucleus fissions. Each nuclear fission reaction releases two neutrons, which cause fission in two nuclei, releasing four neutrons, and so on starting a chain reaction. In this investigation you will investigate the nuclear chain reaction inside a reactor and control the reaction rate using control rods. Control rods are made out of a material such as cadmium that absorbs neutrons. The control rods move in and out of the reactor core to allow fewer or more reactions by regulating the number of fission-producing neutrons.
Controlling the nuclear chain reaction inside a nuclear reactor

How to use the interactive simulation of control rods in a nuclear reactor
  1. Launch the interactive simulation. Press [Run] to start fission reactions by allowing neutrons into the reactor.
  2. Move the control rods up and down to control the nuclear chain reactions.
  3. Monitor the temperature probe to keep the reactor within its safe operating range as you adjust the control rods.
  4. Note the length of time you kept the reactor within the optimal temperature range.
  1. What is required to start the first nuclear reaction? Write down the nuclear reaction equation to back up your answer.
  2. What happens to the chain reaction when the control rods are fully inserted into the reactor? What happens when the rods are fully removed?
  3. What happens to the temperature inside a nuclear reactor if the control rods are fully removed? How could this be a safety issue?
  4. Determine the optimal position of the control rods to produce a steady power output for the nuclear reactor. Explain why this position makes sense to control a nuclear chain reaction.
Read the text aloud
In this interactive simulation, you will control the nuclear reactions occurring inside a nuclear power plant using the control rods. Moving the control rods in and out of the reactor core changes the rate at which the nuclear reactions occur.

Previous Page Next Page815