Nuclear Fission Essay Example | Topics and Well Written Essays - 1000 words

Nuclear Fission - Essay Example A uranium atom is bombarded by slow moving neutrons. Nucleus that split produce three neutrons creating a chain reaction that must be controlled. Control in a nuclear reactor is obtained by using two isotopes of Uranium and . does not split when bombarded with neutrons and thus stops the chain reaction. Graphite modulators and control rods are also used in nuclear reactors to control the nuclear fission reaction. Graphite modulators slow down the fast moving newly generated neutrons. Carbon rods are moved in and out of the reactor to absorb neutrons and control or complete stop the nuclear fission reaction. The main disadvantage in using nuclear fission reactors is the disposal and storage of nuclear waste which remain very harmful for several thousand years. The sun generates its heat energy by using nuclear fusion reactions that takes place on the sun. Even though, both nuclear fusion and fission generate energy. However, fusion is the reverse of fission. Fission is simple in relation to fusions. Fission requires lots of highly radioactive material, creating by-products with very long half-lives, whereas fusion uses only small amounts of fuel. Fusion occurs when light atomic nuclei are forced close enough together that they combine to form heavier nuclei. On the other hand fission heavy nuclei are broken downs into lighter fragments (POST 2003, p.1). Controlling fusion reactions involves the use of two light nuclei, deuterium and tritium, which are isotopes of hydrogen. Fusion takes place when the nuclei obtain enough energy to overcome their mutual repulsion, they can undergo the fusion reaction shown in the following figure: Figure 1: simple Fusion Reaction Nuclear fusion reactions involve the fusion of two nuclei to generate helium and a neutron in addition to a large amount of energy. The particles form a high density and super hot ionized gas called plasma. At high temperature the electrons escape from the nuclei producing a plasma of positive ions. To create nuclear fusion reactions on earth, the plasma must be confined to minimize heat losses from the system. Nucleogenesis: Lithium is generated in the stars by the process of nucleogensis. This process uses the most abundant elements of hydrogen and helium to generate lithium. In the sun, the nearest star, a large quantity of energy is generated when hydrogen is converted into helium by the following nuclear fusion reaction: (Woods 2006, p9) After hydrogen is used up in the sun, a new series of fusion reactions occur in which helium generates beryllium, which then reacts with helium to generate carbon, which then reacts with helium to generate oxygen, which then reacts with helium to generate neon, which then reacts with helium to generate magnesium. All of these fusion reactions generate energy in addition to the different elements that are produced as shown in the following series of reactions (Woods 2006, p9): Once helium is used up, carbon regenerates hydrogen and helium in addition to a number of other elements as demonstrated in the following fusion