By Allison Kubo Hutchsion Although humans first witnessed nuclear reactors in 1942 with the development of the Chicago-Pile by Enrico Fermi, natural fission reactors existed billions of years ago. Fission is the process of breaking apart atoms of heavy elements such as uranium. Energy is released during fission in the form of heat and can be harnessed in fission reactors to produce electricity. Fission is separate from radioactive decay where an atom spontaneously emits some radiation which can be timed by the half life. Fission is instead initiated by a neutron colliding with an atom and splitting it. One fission pathway commonly used is that of U 235 , a uranium atom which has an atomic weight of 235 with 92 protons and 143 neutrons. In order to produce fission a fission event, an atom of U 235 is bombarded by a neutron when this neutron collides with the atom it splits into two fission products and produces heat and more neutrons. If these neutrons then collide with another U 235
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