Chapter 25: Nuclear forces and Nuclear Energy

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You have a serious problem. Your standard of living depends on access to a source of energy and the source you depend on (fossil fuels) is slowly running out. Moreover, the vast majority of people in the world use much less energy than you do, and they covet your standard of living. In this chapter we talk about some possible solutions to your problem and point out some of the tough decisions that face you and future generations. Remember: Nature has solutions to the problem if you don't find a better one. They are called disease and starvation. The "strong interaction" holds the nucleus together. It is (weaker, stronger?) than the electromagnetic interaction in the nucleus; it is a (short, long?) range force that is not felt beyond the size of the ; and, it only affects some kinds of particles. Protons and "feel" the strong force, but electrons, photons, and neutrinos do not. Within the nucleus, protons and neutrons (repel, attract?) one another by the strong force. As a result, there is nuclear (kinetic, potential?) energy stored in the nucleus. If nucleons in the nucleus can rearrange themselves so that on the average they are (closer, farther?) apart/together, nuclear potential energy decreases. If the reduced nuclear potential energy is transformed to energy, we may make use of the energy to do the work of mankind. There are two schemes to release nuclear potential energy: fusion and fission. (Fission, fusion?) is the welding together of two nuclei. Practical schemes to release energy use two isotopes of hydrogen as fuel: and tritium. Good News: Deuterium is plentiful; it can be extracted from (the) . Tritium is (plentiful, not plentiful?) ; but it can be created from a relatively common element, . Bad News: The nuclei of deuterium and tritium are charged particles that (attract, repel?) each other (by the electromagnetic force) until the particles are within the very small range of the strong force. To drive the particles within ths range, we must increase their temperature to about 50 (thousand, million, billion?) degrees Celsius. One of the foremost technological problems of our time has been to try to find a way to confine plasmas of this high temperature at great enough density and for long enough time to allow useful amounts of energy to be released. We have made enormous progress in the past 50 years, but the devices are becoming ever more expensive and we are still not there yet. Nevertheless, fusion promises an almost unlimited and relatively clean source of energy. (Fusion, fission?) is the splitting apart of a heavy nucleus. Nuclei with many nucleons get big enough that nucleons on one side of the nucleus get out of range of the strong force of nucleons on the other side, BUT not out of range of the electromagnetic (attraction, repulsion?) . Some nuclei that are not quite unstable to fissioning can be made so if a is shot into them. If the nucleus then fissions and produces on the average at least (number, how many?) more neutrons, one can set off a so-called reaction that releases a great deal of energy. A "nuclear reactor" is a device to control this release of energy. "Fuel rods" are made of the fissionable material (U235 or Pu239); "Control rods" (that absorb neutrons and slow or stop a chain reaction) are made of ) (graphite, cadmium, uranium?) ; and a "moderator" (that slows the neutrons) can be made of graphite or water. Good News: Fuels is available or can be made from relatively plentiful uranium-238; the technology exists and works and new technologies have made reactors much safer; fission reactors are already used around the world to produce electrical power. Bad News: sources of fuel are not uniformly distributed around the earth nor unlimited; reactors can also be used to produce plutonium for bombs; and we don't quite know what to do with the radioactive waste material from the reactors.

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