Inside the Fission Reactor Chamber
Heavy and radioactive nuclei like Uranium undergo fission forming smaller nuclei and in the process release energy. Nuclear power stations set up nuclear fission reactions and tap this released energy. Fission process is initiated by bombarding heavy nuclei with neutrons.
The 4 key components inside the reactor chamber are listed below.
- Fuel: A nuclear fission reaction is the process of a heavy nucleus breaking up into smaller nuclei. The larger the radioactivity of the nucleus, the lower the energy needed to split it. Specific isotopes of Uranium (U-235, U-328) and plutonium (Pu-239) are the nuclei that are widely used. Nuclear fuel is packed into rods (fuel rods) and placed in the reactor chamber and exposed to a neutron beam.
- Moderator: Neutrons of different speeds are needed to cause fission in different types of reactors. So the speed of neutrons need to be moderated and brought to the ambient speed to obtain maximum efficiency. Materials used for this purpose are called moderators. As the neutrons collide with these moderator particles, they lose some energy and slow down to the required speed. Common moderators are water and graphite.
- Control rod: During fission process, an average of 2.5 neutrons are emitted per fission. If all of these neutrons are allowed to cause another fission each, the reaction becomes uncontrolled. To keep the reaction under control, only 1 neutron should be allowed to pass on and cause the next generation of fission. Control rods are used to maintain the concentration of neutrons in the reactor. These control rods can be inserted to different depths for different neutron concentrations. If they are completely inserted, the reactor shuts down. Boron, Indium and Cadmium are common materials used for the purpose.
- Heat exchanger: The heat released in the process is carried by the daughter nuclei as kinetic energy. Heat exchange tubes surround the reactor to absorb this heat and transport it to an energy converter. Water is the commonly used heat exchanger in power plants. The energy converter further converts this heat into different usable forms of energy.