Fission Reaction History Impact on Society and Environment
... Nuclear fission in the most simplistic terms is the splitting of an atom, Uranium 235 for example, into two roughly equal pieces. ... Enrico Fermi first demonstrated fission in 1934, although he did not realise it at the time. ... For this reaction to be of use as a source of power, it must occur in a chain reaction. In a fission chain reaction, the neutrons released by the splitting of the initial nucleus must then react with more nuclei, which then split to produce more neutrons, etcetera. If the number of neutrons that are captured in fission reactions is greater than the sum of the neutrons that escape and the neutrons that are captured in a non-fission reaction, then a chain reaction will occur. The critical mass refers to the minimum amount of fissionable material need to sustain a chain reaction. Unfortunately fission reactions are most likely to occur when a thermal neutron is involved, that is one moving at low speed. Because the neutrons expelled by a fission reaction are high speed, moderators are used to slow them down. ... 6 X 10-19 J) = 931 MeV/u Therefore the final energy equivalence is, per deuteron: The mass defect, and energy equivalence can also be determined for a fission reaction: 236. ... kr and Encyclopedia Britannica 1984 Edition Impact on Society Many people will argue that it is the dropping of the atomic bombs on Hiroshima and Nagasaki in August 1945 that ended the world war, and fascism. ... On December 2 1942, the first self-sustaining nuclear reaction was supervised by Fermi, and witnessed by many of the world’s greatest physicists. ... In the nuclear reactor, control rods made of neutron absorbing materials control the chain reaction. This reduces the amount number of neutrons available to initiate fission, so the reaction occurs slowly, releasing energy at a useable rate. The atom bomb, however, contains no such material, and the chain reaction is allowed to expand at an exponential rate, limited only by the amount of fuel, and the time before the critical mass is blown apart by its own force. ... Environmental Impact Nuclear reactors produce a range of radioactive wastes varying in radioactivity and half-life. ... Spent fuel rods make up the majority of high level radioactive waste from fission reactors.