Splitting an atom or nuclear fission is a saying we hear from time to time. After the discovery of the nucleus in the atom in 1911, it was found that these atomic nuclei, which were bombarded with particles from radioactive substances, could breakdown and eventually produce a large amount of energy. The uranium, which has the heaviest nuclei, and its isotopes were split by neutrons. Otto Hahn (1879-1968) and Lise Meitner (1878-1968) discovered that the uranium nucleus can be divided into two.
Splitting an atom
In the process called “fission”, additional neutrons are born and these neutrons cause the fission to continue in a chain reaction. In 1942, a research team led by Enrico Fermi (1901-1954) succeeded in carrying out a chain reaction in the world’s first nuclear reactor. Three years later, the same chain reaction was used in nuclear bombs that destroyed Hiroshima, and Nagasaki in Japan.
The energy source in a nuclear reaction or nuclear explosion is chain reactions. A uranium or plutonium nucleus is split by fission, new neutrons emerge, and these neutrons cause new nucleus fissions. As a result of the energy and radiation of the divided parts, a huge amount of heat is released. This heat is used in reactors to generate electricity in a controlled manner. The heat generated by the explosion is much more severe than this.
Let’s explain this process step by step:
Splitting the atom in the family
In 1917, Lise Meitner and Otto Hahn discovered a new element in uranium ores, called protactinium. In 1939, Meitner and his nephew Otto Frisch (1904-1979) performed the uranium fission. Otto Hahn worked on the breakdown of neutrons and uranium nuclei. By-products of this disintegration process included barium nuclei, which weighed half the uranium nuclei. This one family to remember when it comes to breaking down the atom.
A richer fuel: U-235
Fuel rods consist of parts of a uranium compound called uranium dioxide, which contains a high content of uranium-235. These rods are used in the Magnox reactor and the British Advanced Gas-Cooled Reactor-AGR.
Unstable uranium: uranium-238 (U-238)
The main isotope of uranium is uranium-238 (U-238). Its nucleus contains a total of 238 particles, including 92 protons and 146 neutrons. Neutrons prevent the protons in the nucleus from pushing each other due to the positive charges. However, an unstable U-238 nucleus spontaneously decays, it emits an atomic particle, and eventually turns into a thorium nucleus. The thorium core is also unstable. Therefore, with this chain decay process, it becomes different particles and the process continues until a lead nucleus is formed.
Other uranium isotopes also go through similar chain decay processes and turn into a different isotope of lead. This feature allows the rocks containing uranium to be discovered by looking at their radioactivity. Uranium can also breakdown through fission, which can cause a chain reaction. Special conditions must be met for such a chain reaction and a sufficient amount of relatively pure uranium should be used.
Warnings about the atomic bomb
40 years before the first nuclear explosion, in 1905, Albert Einstein (1879-1955) showed in the Theory of Special Relativity that energy and mass are equivalent and can convert into each other. In 1939, he warned American president Roosevelt that the uranium chain reaction could be dangerously used to make a very powerful bomb.
Robert Oppenheimer (1904-1967) joined the US atomic bomb project in 1942 and later became the head of the lab that would make the first nuclear bomb. In 1954, after his dismissal for security reasons, he put an end to his atom studies.
This magical blue glow in the heart of the nuclear reactor is caused by light-emitting electrons as they pass through the medium. In such reactors, the chain reaction is controlled by rods containing neutron-absorbing materials such as cadmium. Severe heat in the reactor’s core is removed with the help of gas, liquid metal, or high-pressure water.