Nuclear fusion and nuclear fission

Nuclear fission and nuclear fusion are two types of nuclear reactions. Fission means dividing and fusion means combining. Therefore, in the fission reaction, a heavy nucleus of an atom is bombarded to split and in the fusion reaction, two lighter nuclei are heated to a high temperature so that they combine to form a heavy nucleus . Read on for more details on nuclear fission and fusion.

A physical reaction that causes a change in the nucleus of an atom is called a nuclear reaction, and the energy released during this reaction is called nuclear energy . The mass of the nucleus serves as a source of nuclear energy that is released mainly in the form of heat. There are two types of nuclear reactions. Are:

• i) Nuclear fission
• ii) Nuclear fusion

What is nuclear fission

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 . 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.

Furthermore, 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 . 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 . 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.

Nuclear power plants

Nuclear power plants use nuclear fission reactions to generate electricity, and the fuel used for this is uranium-235 .

In a nuclear power plant, a fission reaction takes place in a steel pressure vessel, and inside is a nuclear reactor. In a nuclear reactor , rods of uranium-235 are inserted into a graphite core. This is called a moderator because it helps to slow down the neutrons for a proper fission reaction to take place. Boron rods are placed between the uranium-235 rodsAs they help absorb excess neutrons and prevent the nuclear fission reaction from getting out of control. These are called control bars. The nuclear rods can be lifted into or out of the reactor depending on the demand. The nuclear reactor is enclosed in a concrete chamber that has a thick wall so that it can absorb nuclear radiation.

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 . The latter is used to turn turbines and run generators.

An 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).

The spent steam exiting the turbine chamber passes through the condenser containing water and is cooled. This steam is then converted into water and through the pipes is sent back to the heat exchanger. The waste material produced in the nuclear fission reaction of uranium-235 is radioactive and extremely harmful to the environment .

Nuclear bomb

A nuclear bomb is based on the nuclear fission reaction of uranium-235 and plutonium-239 . The fission reaction is deliberately allowed to get out of control to produce a large amount of energy in a very short time.

Nuclear bombs based on said nuclear fission were dropped on the Japanese cities of Hiroshima and Nagasaki in 1945 during World War II. This caused a tremendous loss of human life.

Which is nuclear fusion

The meaning of fusion is to join or combine . Therefore, the process in which two nuclei of light electrons combine to form a heavy nucleus is nuclear fusion. An enormous amount of energy is also released in the process of nuclear fusion.

The nuclei of atoms are positively charged and therefore repel each other. So to combine or fuse these two nuclei to form a heavy nucleus, a lot of heat energy and high pressure is required . This shows that nuclear fusion is carried out by heating lighter atoms to an extremely high temperature under high pressure. Some mass is also lost in this process, providing an enormous amount of energy.

For example, when deuterium atoms are heated to an extremely high temperature under high pressure, two deuterium nuclei combine to form helium which has a heavy nucleus, a neutron is emitted, and a lot of energy is released.

A nuclear fusion reaction is the opposite of the nuclear fission reaction. The energy produced in this reaction has not yet been controlled and is much more powerful than the nuclear fission reaction.

Hydrogen bomb

Nuclear reactions that occur at extremely high temperatures are called thermonuclear reactions . This reaction is used to produce hydrogen bombs that cause massive destruction. The isotopes of hydrogen, deuterium (2H) and tritium (3H) , along with an element called lithium-6 , are used to make a hydrogen bomb. The explosion of it is carried out by an atomic bomb. This is because when an atomic bomb explodes, its fission reaction produces a large amount of heat that raises the temperature of the deuterium and tritium in a few microseconds. This is how the fusion reaction takes place and the hydrogen bomb explodes producing enormous energy.

Advantages of nuclear energy

• It produces tremendous energy from a small amount of fuel (uranium-235).
• It is not necessary to put fuel over and over again in a nuclear reactor. Once the fuel (uranium-235) is put into the reactor, it can run for two to three years in a row.
• It does not produce gases such as carbon dioxide or sulfur dioxide.

Disadvantages of nuclear energy

• Waste products from nuclear reactors are radioactive and continue to emit harmful radiation.
• Risk of accident in nuclear reactors that can cause leakage of radioactive material.
• The availability of uranium as a fuel is limited.
• The high cost of installing a nuclear power plant.