|
Fission, Chain Reactions and the Atomic Bomb By: Kristian Basaraba Curricular Fit: Physics 30 Unit 4: Nature of Matter; Concept: Nuclear fission and fusion are nature’s most powerful energy sources; STS Connections: evaluating, qualitatively the risks and benefits of using fission and/or fusion as commercial sources of energy… Atomic fission was discovered in the winter of 1938-1939. This was a major event in the history of science since it was thought that atoms were indestructible. Obviously, this was not the case. FISSION Fission is basically the splitting of an atomic nucleus into roughly equal parts. As a result of this ‘splitting’ two significant events occur. First of all, there is a tremendous amount of energy released when this occurs. The amount of energy released is in the range of "approximately 100 million to several hundred million volts." Secondly, every time a nucleus undergoes fission, neutrons are released. As more neutrons are released it in turn causes another nucleus to split creating yet more neutrons. CHAIN REACTIONS This second event is important in that it causes a chain reaction to take place that further creates even more energy to be released. Therefore, one can just imagine the possibilities and implications of such a technology on society. The discoveries of fission and chain reactions helped pave the way for the atomic bomb. The main problem however was finding a suitable candidate that could undergo fission with relative ease. URANIUM The best candidate was Uranium-235. It was the best choice for two reasons. One, it has the largest atoms of any natural element which means they were not held together as strongly as the other elements. Secondly, Uranium contains more neutrons than protons in the nucleus, which is important for a chain reaction to occur. The main problem with using U-235 is that it is difficult to extract. This is because the ratio of conversion from ore to metal is 500:1. To further the problem 99% of this metal is in the form of U-238 the remaining 1% is U-235. Scientists worked on this problem and solved it through the use of gaseous diffusion that enabled them to separate the two isotopes. This began the process of creating a bomb. MANHATTAN PROJECT These discoveries led to what is now known as the Manhattan Project. This was a huge scientific undertaking and collaboration of some of the most brilliant scientific minds. The main scientist that overlooked the operation was J. Robert Oppenheimer. This group worked for six years to create the first atomic bomb code-named The Gadget. On July 16, 1945 the first atomic test was performed and was a success. After the scientists realized the destructive power they unleashed they began to doubt what they had done. Oppenheimer quoted a Hindu scripture from Bhagavad Gita "I am becoming Death, the destroyer of worlds." HIROSHIMA AND NAGASAKI On August 6, 1945 the world witnessed perhaps the most catastrophic event in history, the detonation of the atomic bomb on Hiroshima. In a matter of seconds 66,00-78,000 people were instantly killed from the blast. Three days later another bomb was dropped on Nagasaki. As a result of this bomb 39,000-100,000 people were killed. These numbers given are only a rough estimate of those killed directly from the blast it does not however reveal the deaths that have occurred from prolonged exposure from the radiation that is produced from the bombs not to mention the horrifying effects of this radiation. On the other hand, the bomb did serve its purpose it did end the war. Questions Was the use of the bomb justified in ending WWII? Should we stick with the advantages of nuclear energy or should we get rid of all nuclear related equipment in fear of this happening again? Consider Chernobyl and Three Mile Island. What responsibilities do scientists have to humanity when creating weapons for war? Do they have a responsibility or are they "just doing their job?" Should scientists be held responsible for the innocent people killed as a result of the weapons they produce for war? Should we charge them as war criminals like some Nazi scientists were at the Nuremberg trials? Outline the benefits, if any, of using nuclear energy in today's society. References Field, Dennis. 1985. Science: process and discovery. Addison-Wesley 1985. www.toda.org/publications/peace_policy/p_p_s98/rotblat.html http://library.thinkquest.org/3471/nuclear_weapons_body.htm http://inventors.about.com/science/inventors/library/weekly/aa050300b.htm |