Peaceful uses of nuclear energy on the earth — fission and fusion
In 1938, the joint discovery of physicists Otto Hahn and his student Lise Meitner was that if you strike a heavy atom like radium, plutonium or uranium 235’s nucleus, it will break the nucleus and more neutrons will come out. These atoms have heavy nuclei with lots of protons and neutrons and they possess radioactive properties.
If we hit the nucleus very fast, then the neutron goes straight through and nothing happens. However, if the neutron strikes the nucleus very slowly, the nucleus actually breaks down and neutrons are ejected from it. This scenario is just like a bullet hitting a window.
The binding energy in the nucleus comes from strong nuclear force, one of the four fundamental forces of nature. The energy is released during these reactions known as fission reactions as a slow neutron strikes a heavy nucleus and the energy is converted to mass according to Newton’s famous special relativity equation, E=mc2.
A chain reaction starts as rudimentary things like neutrons come out of one nucleus and strike others. This goes on as billions of neutrons are ejected along with huge amounts of energy called atomic or nuclear energy. This scenario is comparable to an avalanche of stones coming down a mountain. As stones come down, they knock over more stones on their way down. A few grams of uranium are enough to cause a giant nuclear explosion.
In 1945, the secret project, Project Manhattan was carried out to make fission chain reaction successful. Scientists wrote to then US president, President Roosevelt about making nuclear atomic bomb practically possible.
However, the intentions were peaceful as controlled reactions were born in mind. They focused on as you like stop and start of fission reactions by increasing or decreasing speed of the neutrons involved in the reactions to generate controlled amounts of nuclear energy.
The process required heavy atoms as fuel such as radium, plutonium or uranium and slowing down fast neutrons using moderators called carbon, graphite and heavy water. Then uncontrolled energy would be released which was a reality in Hiroshima Nagasaki, in August 1945 during world war II, when the atom bombs little boy and fat man were unleashed on Hiroshima and Nagasaki in Japan, respectively.
Massive amounts of energy were released that caused explosions, shock waves and killed millions of people and caused their dead bodies to evaporate. A lot of radiation was released that had carcinogenic outcomes among the inhabitants of the region and beyond.
Besides a moderator, the fission bomb reaction also needs a controller or control rod like cadmium that absorbs neutron energy. Moreover to protect against death and the harmful effects of radiation, a protector is also required.
The process of taking measures to prevent death and carcinomas resulting from radiation, spent fuel disposal, which are safety methods, is crucial.
More incidents of radiation horror as an outcome of nuclear reactions in nuclear reactors, which actually had peaceful intentions, include the Chernobyl disaster explosion in Ukraine, in 1986. Due to the radiation, food and water were contaminated.
Another disaster was the recent Fukoshima earthquakes in Japan that broke the radiation protector and caused the radiation to travel thousands of miles and even reach Bangladesh to threaten the inhabitants with the fatalities of radiation.
In order to create peaceful and controlled reactions, we need uranium 238, which many countries need to import. They have uranium 235 which needs to be converted to uranium 238 to make the fission fuel. The conversion is an expensive process. Moreover uranium 238 is rare in many countries and they need to import it as mentioned. Moreover, not everyone has access to purified uranium 235 either. Therefore not all nations can produce nuclear energy.
Fission reactions can actually be employed to peaceful uses because they generate a lot of heat energy that can boil water, which turns to steam that can be used to drive a generator to produce electricity.
Fusion reactions are another type of nuclear reaction that requires light nuclei like hydrogen atoms. As many hydrogen atoms come together, they fuse together to form deuterium and then helium atoms. These atoms are isotopes of each other as they have the same number of protons but different number of neutrons. Thus heavier nuclei are formed from light ones.
This is a process that has been taking place in stars and our own sun continually. Stars have ample fuel with 75% hydrogen content and 24% helium resulting from the fusion reactions. The process is also a chain reaction as billions of hydrogen atoms participate and release thermonuclear energy.
After helium atoms are formed they break down due to the extreme heat in the stars interior to produce new hydrogen atoms that participate in further fusion reactions to release thermonuclear energy. Hence the name chain reaction and the stars never run out of supply of hydrogen atoms.
However unlike fission reactors, there are no available fusion reactors since we cannot bring hydrogen nuclei together which are positive and have electrostatic or electromagnetic repulsive forces acting when they approach each other.
To overcome this strong electrostatic attraction, we need huge amounts of energy such as an atom bomb itself which will cause the hydrogen to evaporate and things to melt. Hence these reactions are not desirable as atom bombs are not peaceful.
Nevertheless, these reactions are very feasible in the stars and the sun because they already have huge reserves of heat due to their massive mass which can make it possible to overcome the strong electromagnetic forces between hydrogen nuclei and cause the fusion reactions.
The dream fusion energy of scientists is from water because its constituent is hydrogen and chemical breakdown of water is very easy and it is a relatively cheap procedure.
Fusion reactions in the sun are vital for the beginning of life as this is the phenomenon from which photosynthesis could be achieved in plants and protozoa. This is vital for the existence of life.
Fusion reactions also can be used to make hydrogen bombs which have disastrous manifestations in history.
