Fission and Fusion Radioactive decay is an example of fission , the splitting of a nucleus into smaller pieces. There is another form of this process: A heavy atom can be struck by a high-speed particle, such as a neutron, contributing enough energy to cause the nucleus to split more or less evenly. A typical example is the fission of uranium-238, where the possible primary end products are a couple of smaller radioactive nuclei and several more neutrons: 92 238 U +0 1 n ! 53 131 I + 39 105 Y + 30 1 n . Of course, not every U-238 fission will produce iodine-131, but if it does, great care must be taken not to let it contaminate foods as it can end up stored in the thyroids of people who are iodine deficient—especially children—and lead to cancer. There is a similar danger when bones store strontium-90. The neutrons resulting from the U-238 fission are not fast enough to break another U-238 nucleus, but there is a form of uranium for which they would be: U-235. Separating it from U-238 is very difficult as they are chemically identical. The easiest method is to
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This note was uploaded on 04/05/2012 for the course PHYS 131 taught by Professor Tibbets during the Spring '11 term at Cuyamaca College.