On August 6th, 1945, the world woke up to the ghastly devastation of Japan’s Hiroshima city and truly understood the immense power of an ‘atom’ bomb. Just when mankind was recovering from horrific aftermaths of Hiroshima and Nagasaki bombing, a stronger, more powerful ‘hydrogen’bomb was tested on November 1st, 1952 at Marshall islands. While we totally agree that it is inhumane to use nuclear weapons of mass destruction, the curious science geek in all of us might have wondered what makes these nuclear bombs so powerful. Atom bombs work on the principle of nuclear fission and hydrogen bombs work on the principle of nuclear fusion. Let’s take a moment to understand what nuclear fission and nuclear fusion are all about.

Nuclear Fission

  In nuclear fission, an atom of unstable radioisotope is bombarded with a neutron that causes the nucleus to split releasing more neutrons and a large amount of energy. It is said that the energy that is released is from the force that is used to bind the nucleus together. The neutrons that are released go on to bombard other nuclei of the radioisotope and thus resulting in a chain reaction where more and more neutrons are released along with the great magnitude of energy. Atom bombs use unstable isotopes of Uranium(U-235) or Plutonium(Pu-239) to carry out the nuclear fission reaction. The atomic bomb used on Hiroshima was a uranium implosion bomb whereas the one used on Nagasaki was plutonium based. Let’s take a look at the nuclear fission reaction of Uranium and Plutonium:   When a highly accelerated neutron hits the nucleus of a U-235 atom, it splits into two nuclei, that of Ba-141 and Kr-92, along with the release of three neutrons and a tremendous amount of energy. These 3 neutrons further bombard other nuclei of U-235 and thus creating a chain reaction. When a neutron strikes the atomic nucleus of Plutonium 239, the nucleus splits into smaller fragments while releasing 2 neutrons along with a tremendous amount of energy. These two neutrons go on to disintegrate two more nuclei, releasing more neutrons and more energy.

Nuclear Fusion

In a nuclear fusion reaction, two or more atomic nuclei combine together in extremely high temperatures to form a different element with heavier atomic nuclei. This process also leads to release of subatomic particles like neutron and proton along with lots of energy. Unlike nuclear fission reaction, which doesn’t occur naturally, nuclear fusion reaction can be found on the surface of the sun and is considered to be the source of sun’s limitless energy. An example of nuclear fusion is the reaction between isotopes of hydrogen – Deuterium and Tritium under extremely high temperatures. When Deuterium and Tritium collide at a very high speed, a nuclear fusion reaction takes place where these two nuclei fuse together to form a Helium nucleus, releasing one neutron and 17.5 MeV of energy. The nuclear fission and nuclear fusion reactions might have a devastating effect when they take place in an uncontrolled environment. But, when these nuclear reactions take place in a carefully constructed nuclear reactor where the speed of the bombarding neutron can be controlled, then the energy released can be used to generate electricity. Watch out for this space to know how a nuclear reactor works.
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