Dr. Tsubokura's Radiation Lecture Vol.74
Author: Masaharu Tsubokura
Editors: Akihiko Ozaki M.D., Yuki Senoo
147. The principle of electricity generation in nuclear power plants is the same as in thermal power plants
After the disaster at the Fukushima Daiichi Nuclear Power Plant, many technical terms related to nuclear reactors appeared in newspapers, such as nuclear fuel rod, control rods, and criticality. This terminology is all related to power generation and to the question of how electricity is generated at a nuclear power plant.
In thermal power plants, water is converted into steam using heat energy obtained from the combustion of coal and other fossil fuel. This steam is further used to rotate a turbine, which generates electricity. Turbine generators operate on basically the same principle as mechanically powered flashlights on bicycles or hand-cranked radios, utilizing rotation for power.
In nuclear power plants, radioactive substances are used instead of fossil fuels. When a neutron collides with radioactive uranium, the uranium splits, which catalyzes a release of heat energy. This energy is used to heat water, and the resulting steam rotates a turbine and generates electricity.
Nuclear power plants differ from thermal power plants in multiple aspects, including the control systems for nuclear fission reaction, the management of radioactive substances and waste, the severity of impacts on the surrounding environment in case of accidents, and the nuclear-decommissioning process. On the other hand, both types of power plants generate electricity by revolving a turbine using steam produced by heating water.
148. Nuclear fission reaction occurs in a series of chain reactions
Both nuclear and thermal power plants heat water and generate electricity by revolving a turbine with steam. Dissimilarly to the process in thermal power plants, the heat in nuclear power plants is produced by nuclear fission instead of fossil fuel combustion. Well, this distinction raises the question of what exactly nuclear fission is.
To quickly recap previous articles, every single substance consists of the collection of invisible, minuscule particles called protons, neutrons, and electrons. When the numbers of these particles are unbalanced, the substance becomes unstable and is called radioactive.
In the reactors of nuclear power plants, neutrons collide with radioactive uranium (fuel of the plants), which originally has an unbalanced number of protons and neutrons. These collisions make radioactive uranium become even more unstable and result in splitting, which releases energy.
A notable point is that the fission of uranium will also result in production of new neutrons. These new neutrons will collide with more radioactive uranium and initiate new fission reactions, leading to production of additional neutrons. Eventually, the scale of the fission reactions will grow as one reaction leads to another.
In nuclear reactors, energy is produced in such a way that this chain reaction does not run out of control.
The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on 5th and 12th November 2017 was reproduced for MRIC Global under the author's permission.