Only a few nuclei are known to undergo fission. In nuclear fission a large nucleus is split into two medium-sized nuclei. The source moves along a circular track, rotating the radioactive beam around the patient, so that only the tumor receives continuous radiation. Industry fall into two categories: fission reactions and fusion reactions.įIGURE 4.5 Cancer treatment with cobalt-60. The nuclear reactions presently used or studied by the nuclear power Of effort and expense has gone into developing nuclear reactors as a source The first nuclear reactor to achieveĬontrolled nuclear disintegration was built in the early 1940s by Enrico FermiĪnd his colleagues at the University of Chicago. A fifth characteristic of nuclear reactions is that Nuclear decay that form the basis for the use of radioisotopes in the healthĪnd biological sciences. In the previous section we listed four characteristics of radioactivity and Thus, if a heavy nucleus splits in half, then about 1 MeV per nucleon, or approximately 240 MeV per fission, is released. The graph in Figure 2 shows BE/ A to be about 7.6 MeV/nucleon for the heaviest nuclei ( A about 240), while BE/ A is about 8.6 MeV/nucleon for nuclei having A about 120. The amount of energy per fission reaction can be large, even by nuclear standards. Figure 2 shows that BE/ A is greater for medium-mass nuclei than heavy nuclei, implying that when a heavy nucleus is split, the products have less mass per nucleon, so that mass is destroyed and energy is released in the reaction. As noted in Fusion, energy is released if the products of a nuclear reaction have a greater binding energy per nucleon (BE/ A) than the parent nuclei. (credit: Kalmthouts)įission is the opposite of fusion and releases energy only when heavy nuclei are split. The reactor is in the small domed building to the left of the towers. The cooling towers are the most prominent features but are not unique to nuclear power. About 16% of the world’s electrical power is generated by controlled nuclear fission in such plants. The people living near this nuclear power plant have no measurable exposure to radiation that is traceable to the plant. China is building nuclear power plants at the rate of one start every month.įigure 1. France provides over 75% of its electricity with nuclear power, while the US has 104 operating reactors providing 20% of its electricity. By the end of 2009, there were 442 reactors operating in 30 countries, providing 15% of the world’s electricity. Whereas nuclear power was of little interest for decades following TMI and Chernobyl (and now Fukushima Daiichi), growing concerns over global warming has brought nuclear power back on the table as a viable energy alternative. Hundreds of nuclear fission power plants around the world attest to the fact that controlled fission is practical and, at least in the short term, economical, as seen in Figure 1. Controlled fission is a reality, whereas controlled fusion is a hope for the future. Nuclear fission is a reaction in which a nucleus is split (or fissured).
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