NUCLEAR+FISSION+-+Nathan

Back to 11.3 Presentations **What is Nuclear Fission** Nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller, lighter parts. This reaction often creates free protons and neutrons in the form of gamma rays. One analogy to describe nuclear fission is to imagine marbles. Say 50 marbles are placed in a rough circle, this represents the atom. Then you flicked a marble at the circle of marbles, the marbles flying directions and groups is the same as what happens to the atoms in nuclear fission. Nuclearfission uses chemical energy to produce heat and light energy. Chemical energy from the splitting of the uranium atom causes immense heat. This heat is used to turn turbines which in turn to produce electricity. The energy transfer for this produce is Chemical --> Heat --> Electricity & Heat.

**Example of Nuclear Fission** Uranium commonly used for nuclear fission in power plants to generate power. Uranium is a natural choice for nuclear fission that occurs in nuclear power plants. This is because it undergoes spontaneous fission very slowly. The diagram on the right is showing what occurs in the nuclear fission of uranium 235 (the most common type used in nuclear fission). The diagram on the left shows what happens in a chain reaction. at #1, u235 absorbs a neutron and fissions into new atoms and neutrons. #2 shows how one of the split neutrons is simply lost as it is not absorbed by another atom of u235. #3 shows one of the neutrons colliding with another atom of u235, continuing the reaction. Under controlled conditions, this chain reaction can occur indefinitely as long as there is enough uranium there. The splitting of an Uranium atom causes an enormous amount of heat gamma radiation. The explanation for this large amount of energy results from the fact that the products of the fission and the neutrons together weigh less then the original uranium which was split. This difference in weight is directly converted into energy which was famously expressed by Einstein as E=mc2.

**Is Nuclear Fission a renewable form of energy?** Because of the large amount of energy given off by nuclear fission, it can be used reliably as an energy source. How ever nuclear fission is not a renewable source of energy as uranium needs to be continuously fed in to react to cause energy. It is non renewable because the material which we used to produce the energy cannot be replenished as fast as we use it. Nuclear fission produces nuclear waste as a product which is radioactive. E.g. Chernobyl The radioactive waste loses its radioactivity over time but the waste needs to be isolated for large amounts of time until it no longer poses a threat.

Sources http://www.eia.doe.gov/cneaf/nuclear/page/intro.html http://www.lbl.gov/abc/wallchart/chapters/14/1.html http://en.wikipedia.org/wiki/Nuclear_fission http://environment.about.com/od/nuclearenergywaste/Environmental_Issues_Nuclear_Energy_Nuclear_Waste.htm http://library.thinkquest.org/17940/texts/fission/fission.html