Nuclear fission energy production from

Nuclear fission energy for the commercial production of electricity has been with us since the 1950s. In the United States, about 20 percent of all electrical energy now originates from 103 nuclear fission reactors situated throughout the country. Other countries also depend on nuclear fission energy, as is shown in Figure 19.13. Worldwide, there are about 442 nuclear reactors in operation and 29 currently under construction. 

Nuclear fission energy of the type currently in use has the potential to provide enough energy for the operation of civilization, but it presents much the same supply lifetime problem as fossil fuels. The waste products present a severe environmental problem. The problem is very different from that presented by fossil fuels but possibly more dangerous. Despite much criticism of the use of fission nuclear power, its use may be preferred to fossil fuels because of the lack of other peaceful use for uranium and the fact that the waste products can be confined. Remember, fossil fuels wastes are not confined. They are dispersed through the ecosphere as acid rain and carbon dioxide. 

Uranium is converted by CIF, BiF, and BrP to UF. The recovery of uranium from irradiated fuels has been the subject of numerous and extensive investigations sponsored by atomic energy agencies in a number of countries (55—63). The fluorides of the nuclear fission products are nonvolatile hence the volatile UF can be removed by distiUation (see Nuclearreactors Uraniumand uranium compounds). 

In a nuclear power plant, heat must be transferred from the core to the turbines without any transfer of matter. This is because fission and neutron capture generate lethal radioactive products that cannot be allowed to escape from the core. A heat-transfer fluid such as liquid sodium metal flows around the core, absorbing the heat produced by nuclear fission. This hot fluid then flows through a steam generator, where its heat energy is used to vaporize... 

Tc-99, which has a half life of 2.12 x 10 years, can be recovered from nuclear fission waste in kilogram quantities. Solvent extraction, ion exchange, and volatilization processes are employed to separate it from the numerous other fission products. Because of its long half life and its emission of a soft (low energy) beta particle, it can be safely handled in milligram quantities. Almost all chemical studies of the element have been carried out with this isotope. 

NATURE OF NUCLEAR FISSION REACTIONS The energy of a nuclear fission reaction can be computed from the change in mass between reactants and products according to Einstein s law ... 

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate. Nuclear reactors are used for many purposes, but the most significant current uses are for the generation of electrical power and for the production of plutonium for use in nuclear weapons. Currently, all commercial nuclear reactors are based on nuclear fission. The amount of energy released by one kg 235U is equal to the energy from the combustion of 3000 tons of coal or the energy from an explosion of 20,000 tons of TNT (Trinitrotoluene, called commonly dynamite). 

A direct synthesis of N2F2 in low yield and admixed with other nitrogen fluorides has been reported from the irradiation of N2-F2 mixtures with ra-y-radiation from a nuclear reactor admixed with other high-energy radiation from uranium fission products (85). There is also a radiochemical synthesis of N2F2 (1.5%) and NF3 (42%) when an N2-F2 mixture is irradiated with 30-MeV electrons in an electron linear accelerator (86). Reaction of fluorine diluted with N2 and NH3 also gives some N2F2 (159,213). 

Nuclear fission is a process in which the nucleus of an atom splits, usually into two pieces. This reaction was discovered when a target of uranium was bombarded by neutrons. Eission fragments were shown to fly apart with a large release of energy. The fission reaction was the basis of the atomic bomb, which was developed by the United States during World War II. After the war, controlled energy release from fission was applied to the development of nuclear reactors. Reactors are utilized for production of electricity at nuclear power plants, for propulsion of ships and submarines, and for the creation of radioactive isotopes used in medicine and industry. 

This was the first man-made radionuclide. From that time on many species of radionuclides were produced by bombardment of elements with charged particles using the various types of accelerators. In addition, practical use of fission energy allowed production of a great amount of artificial radionuclides, not only by neutron irradiation generated with nuclear reactors, but also by processing spent fuel. 

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