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2018 | OriginalPaper | Chapter
Nuclear Energy, Introduction
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Excerpt
This section on Nuclear Energy consists of 20 articles that cover all aspects of the nuclear enterprise. Here is a brief description of each article.
1.
Fission reactor physics. Fission reactors generate the energy used for the generation of electricity. What are the physics principles that make their operation possible? What are their main safety features? These are two of the major items discussed in this article.
2.
Nuclear fission power plants. Once the fission reactor is designed and ready to operate, how is the fission energy utilized to generate electricity? The reactor core itself is not enough to complete the task. Many other components are needed for the successful transformation of the energy released in fission into electricity: pumps, steam generators, diagnostics, radiation monitors, etc. It is this side of nuclear power, components, and activities outside the core, which is described in this article.
3.
GEN-IV reactors. By any measure, current fission reactor designs are successful. However, there is room for improvement in many areas such as fuel utilization, thermal efficiency, passive safety features (that do not require operator action or need electric power to be activated), multiuse of the heat generated. There is considerable global effort underway to design fission reactors that will show some, if not all, of the improvements just mentioned. The new designs, collectively named GEN-IV reactors, are described in this article.
4.
Small Modular Reactors (SMR): In addition to the GEN-IV effort (article 3), there is a parallel effort to design reactors with an electric power of up to 300 MWe. These reactors are designated as Small Modular Reactors (SMR). The word “modular” refers to a feature of their design that will make possible their construction in modular form, thus reducing construction time and cost. The various SMR designs and their advantages are described in this article.
5.
Isotope separation methods. The two elements found in nature that may be used as fuel for the fission reactors operating today are Th and U. Unfortunately, only certain isotopes of these elements, or made with the help of these elements, can be manufactured into fuel, and these “useful “isotopes are in short supply (e.g., 235U is only 0.711% of natural U). Hence, isotope separation methods must be employed for the concentration/enrichment of the useful isotopes. These methods are discussed in this article.
6.
Nuclear reactor materials and fuels: For a successful and long-term safe operation of a nuclear power plant, the materials used, especially those directly tied to the fuel, must function as designed (as expected) in the very hostile environment of the nuclear fission core. This article describes the pros and cons of the various materials that have been considered and the final choices made.
7.
Modern nuclear fuel cycles. Providing fuel for a fission reactor is not a simple or straightforward task; it involves many steps (U procurement, conversion to UF6, enrichment, fuel rod, and assembly fabrication). The users of the fuel are presented with choices, such as discarding the used (irradiated) fuel as waste or reprocessing and recycling it. Also, nuclear reactor designers may affect the nuclear fuel “cycle” by building reactors that only produce electricity, or combine electricity production with generation of new fuels (breeders), or generate electricity in combination with burning some of the nasty byproducts of the fission process. These are the matters discussed in this article.
8.
U and Th resources. U and Th are the only two elements which exist in nature and can be used as nuclear fuels for fission reactors. It is important, therefore, to address questions such as: How much U and Th is there on earth? Where are they found? What is the cost of their recovery from the ground? These questions are answered in this article.
9.
Nuclear fuel reprocessing. Used (irradiated) nuclear fuel contains many useful isotopes. Primarily Pu and U. Reprocessing is the operation that is employed to extract the useful isotopes form the used fuel. The reprocessing methods used until today and those under research and development are discussed in this article.
10.
Nuclear facilities decommissioning. Every nuclear facility has a finite lifetime; at the end of its designed life, when operations stop permanently, the law requires that the site must, eventually, be returned to its preoperational status, i.e., available for public use. Reaching that stage, it means that radioactive materials must be removed to such an extent that the radiation exposure rate returns, practically, to background levels. This is what decommissioning means. All the tasks associated with decommissioning are discussed in this article.
11.
Radioactive waste management-Storage-Transport-Disposal. The operation of fission reactors results in the production of radioactive materials. Such materials, if they have no further use (in which case they are “radioactive wastes”), must be safeguarded for long periods of time in order that their release to the biosphere be prevented. The method of eventual disposal of radioactive wastes considered today is placement in a geologic repository. In the meantime, radioactive materials must be stored and transported. All activities related to these tasks are the subject of this article.
12.
Nuclear Fusion. Although fusion became known to man before fission and life on earth owes its existence to a fusion reactor in the sky (our Sun), no fusion plant to produce electricity has been built yet. The reason for not having fusion reactors yet is due to the unique challenges/difficulties encountered for completion of that task. But because fusil reactors offer many advantages, over fission reactors, the world’s scientific community is working as a team in an effort to resolve the issues and build an operational fusion reactor in the “near” future. All the past and present efforts in fusion research and expected future developments are presented in this article.
13.
Nuclear power economics. In a free market, every plant generating electricity must compete, economically, with all other options and nuclear is no exception. Nuclear power is subject to all the rules and regulations of all other options of electricity generation, but it also faces some unique issues with respect to financing. These issues and their potential resolution are discussed in this article.
14.
Radiation sources. Radioactivity and basic ionizing radiation sources are discussed in this article.
15.
Ionizing radiation detectors. Although radioactivity cannot be seen, felt, or tasted, it can be detected to very low levels relatively easily and very accurately. The instruments used (principles of operation, construction, operation, analysis of results) for detection and measurement of ionizing radiation are discussed in this article.
16.
Health physics. Very early in the twentieth century (1920s), it was realized that ionizing radiation may be harmful to humans; therefore, measures must be taken to protect people. These measures were based on (a) quantifying the effects of radiation exposure by defining units of radiation dose and means to measure it and (b) establishing professional bodies that set protection standards [ICRP (1928), NCRP (1964), Health Physics Society (1955)]. The field of Health Physics was thus born resulting in great benefits to radiation workers and the public, with respect to protection from ionizing radiation.
17.
Dosimetry. The instruments and methods used for the determination of radiation dose are examined in this article (complementary to articles 15 and 16)
18.
Radiation shielding and protection. Having discussed radiation sources (#14), dangers form radiation (#16), and standards of protection (#16 & 17), how does one provide the means for a safe radiation environment for workers and the public? How are relevant computations performed? Necessary measurements? How is an effective radiation shield designed? These are some of the questions answered in this article.
19.
Applications of radioisotopes. When we hear “nuclear power,” generation of electricity by nuclear power plants comes to mind. There is, however, another large part of the nuclear enterprise that permeates and benefits our way of life which is the application of radioisotopes (and ionizing radiation, in general) for nonpower applications. I mean, of course, applications in scientific research, industry, food irradiation, home smoke detectors, etc., and of course perhaps the most important of all applications in medicine for research, diagnosis, and therapy. All applications of ionizing radiation are, briefly, discussed in this article.
20.
Nuclear safeguards and proliferation of nuclear weapons materials. Of great concern to human kind is the acquisition of nuclear materials by individuals, groups, or governments with the purpose of using such materials to make nuclear weapons, contrary to international treaties. This “proliferation” or rather “nonproliferation” of nuclear materials is a concern that will never disappear; all that can be done by the international community of nations is to set up treaties, policies, and procedures that diminish the probability of proliferation. It is these aspects of this terrible problem facing humanity that are discussed in this article.