The brackets around U indicate that it has a highly unstable nucleus. In turn, these atoms split apart, releasing more energy and more neutrons. Some of these neutrons are absorbed by other atoms of uranium-235. When a nucleus of uranium-235 undergoes fission, it splits into two smaller atoms and, at the same time, releases neutrons ( n) and energy. Nuclear power plants currently in use depend primarily on the fission of uranium-235 and plutonium-239. Only a few nuclei are known to undergo fission. In nuclear fission a large nucleus is split into two medium-sized nuclei. The source moves along a circular track, rotating the radioactive beam around the patient, so that only the tumor receives continuous radiation. Industry fall into two categories: fission reactions and fusion reactions.įIGURE 4.5 Cancer treatment with cobalt-60. The nuclear reactions presently used or studied by the nuclear power Of effort and expense has gone into developing nuclear reactors as a source The first nuclear reactor to achieveĬontrolled nuclear disintegration was built in the early 1940s by Enrico FermiĪnd his colleagues at the University of Chicago. A fifth characteristic of nuclear reactions is that Nuclear decay that form the basis for the use of radioisotopes in the healthĪnd biological sciences.
The latter is used to turn turbines and run generators.Īn enormous amount of thermal energy is produced when a controlled fission reaction takes place in a nuclear reactor. That is why liquid sodium is continuously pumped through the pipes connected to the reactor. This helps to absorb the heat produced in it. Then, through the pipes, the extremely hot sodium passes through the water in the heat exchanger. The water absorbs the heat from the hot sodium and boils to form steam. Next, this steam passes at high pressure to the turbine chamber which, worth the redundancy, has a turbine. This steam causes it to rotate, and in turn, it is attached to a shaft and the generator. So when the turbine turns, its shaft also turns and drives the generator (which makes it possible to create electricity).In the previous section we listed four characteristics of radioactivity and Now the heat produced due to the fission reaction in the reactor is cooled using liquid sodium or carbon dioxide gas, which also helps transfer it to the heat exchanger. Here with the help of cooling water it is converted into steam. However, the nuclear fission reaction can be controlled by using boron rods, as boron can absorb neutrons. Nuclear fission reactions are carried out to generate electricity in nuclear power plants. If all the neutrons produced during the fission of uranium-235 produce more fission, then so much energy will be produced that it will not be controlled and will cause an explosion called an atomic bomb. This process is called nuclear fission. For example, when uranium-235 atoms are bombarded with neutrons, the heavy uranium nucleus splits to produce barium-139 and krypton-94 with the emission of three neutrons. A lot of energy is also produced in this reaction because the mass is converted to energy.įurthermore, in a nuclear fission reaction, neutrons are also consumed and produced. The neutrons produced in the nuclear fission reaction lead to further fission of heavy nuclei and cause a chain reaction. The heavy nucleus of radioactive atoms such as uranium, plutonium, or thorium is bombarded with low-energy neutrons that divide the nucleus into smaller nuclei. Hydrogen isotopes are used as fuel in experimental plants. Uranium is one of the main fuels in nuclear power plants.
Very few radioactive chemicals come out of this reaction. The fission reaction produces highly radioactive substances. The requirements are a high-density, high-temperature atmosphere. It is necessary to have a critical mass of substance and neutrons at high speed. It takes place in the stars and the Sun which are natural forces. It never occurs in nature in normal cases. The energy produced in nuclear power plants uses this technology.Įxperiments in power plants use this technology. The release of energy during fusion is much greater than that of the fission reaction. The amount of energy released in fission is much less than the energy released during fusion. It takes a lot of energy to combine small atoms into one large atom. It requires less energy to divide the atoms into two or more. Fission would be defined as the division of a single atom into multiple small atoms.įusion would be defined as the joining of two or more small atoms to form a large atom.