Author: Masaharu Tsubokura
Editors: Akihiko Ozaki M.D., Yuki Senoo
149. Generation of heat by a fusion reaction of radioactive uranium
In the previous article, we explained that nuclear power plants generate electricity by turning a turbine using water vapor, which is obtained by heating water with the energy released from nuclear fusion. Furthermore, we explained that radioactive uranium is used as fuel for this nuclear fission reaction.
When a neutron collides with a radioactive uranium atom, the radioactive uranium atom becomes unbalanced and splits, resulting in a release of heat energy. The important thing is that the fission of uranium will also result in the production of a new neutron, which will then collide with another radioactive uranium atom and lead to a new fusion reaction. Radioactive uranium has the characteristics to produce a chain reaction when predetermined conditions are met as this cycle repeats.
This radioactive uranium accounts for a little less than 1% of the total amount of natural uranium. At nuclear power plants, in order to constantly produce heat, the chain reaction gradually takes place in sealed containers using concentrated radioactive uranium of approximately 3〜5%. On the other hand, for an atomic bomb, radioactive uranium in a more than 90% concentration is utilized to produce the chain reaction at an extremely high speed and generate an enormous amount of energy in an instant.
150. Uranium is transformed into plutonium
When a neutron collides with a radioactive uranium atom, the radioactive uranium atom becomes unbalanced and splits, resulting in a release of heat energy. A fission of uranium also results in the production of a new neutron, which will then collide with another radioactive uranium atom and produce a new fusion reaction. Radioactive uranium has the characteristics to produce this chain reaction when predetermined conditions are met, and at the nuclear power plant, this chain reaction is gradually carried out in sealed containers to produce the heat.
This radioactive uranium (uranium 235), which is prone to generating a nuclear fusion reaction, accounts for less than 1% of the total amount of natural uranium, and the other 99% of natural uranium consists of stable uranium (uranium 238). The fuel utilized in nuclear power generation is concentrated radioactive uranium 235 of approximately 3-5%, and stable uranium 238 accounts for more than 90% of the fuel.
In a nuclear reactor, the nuclear fission reaction with radioactive uranium 235 is generated in a chained manner, but from time to time, a neutron also collides with stable uranium 238. This reaction between a neutron and uranium 238 results in the production of plutonium. Plutonium does not exist in the natural environment in general. Thus, it can be said that plutonium is produced as a consequence of nuclear power plant operation.
The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on 19th and 26th November 2017 was reproduced for MRIC Global under the author's permission.