nuclear engineering

Introduction

      the field of engineering that deals with the control and use of energy and radiation released from nuclear reactions. It encompasses the development, design, and construction of power reactors, naval-propulsion reactors, nuclear fuel-cycle facilities, and radioactive-waste disposal facilities; the development and production of nuclear weapons; and the production and application of radioisotopes.

History

      Nuclear engineering began with the first major demonstrations of the utilization of nuclear energy: the development of nuclear weapons and nuclear reactors.

      The World War II Manhattan Project, under which the U.S. government built, in a relatively short period, such facilities as production reactors, chemical-reprocessing plants, test and research reactors, and weapons production facilities, stands out as a monumental engineering feat. Engineers in early programs had to learn about a host of nuclear-related subjects, ranging from reactor theory and reactor control to radioactivity and the behaviour of material under irradiation. They were educated on the job by nuclear scientists and physicists, first through personal discussions and later through seminars and classes. Many of those who entered the field had been educated in other engineering disciplines—mechanical, electrical, chemical, and so on. Nuclear engineering continues today to be a strongly interdisciplinary activity.

Early schools

      In the late 1940s, as the many potential peaceful uses of nuclear energy became evident, two schools of reactor technology were established, one in Tennessee at Oak Ridge National Laboratory and another in Illinois at Argonne National Laboratory.

      In 1946 Clinch College was established at Oak Ridge. In its first year 35 American participants from universities, industry, the U.S. Navy, and government agencies took courses in nuclear technology. They attended lectures, conducted laboratory experiments, and gained hands-on experience in operating nuclear reactors.

      In 1950 Clinch College was succeeded by the Oak Ridge School of Reactor Technology (ORSORT). The participants were again selected from academic, government, and industry sectors. In addition to lectures and laboratory work, the students were assigned to teams working on the development of new concepts. Several concepts developed by these teams later grew into major research and development programs, including the high-flux isotope reactor, the molten-salt reactor, and several nuclear propulsion schemes. ORSORT was disbanded in 1965 because nuclear engineering programs had by that time become widely available at universities and colleges.

      The International School of Nuclear Science and Engineering was established at Argonne National Laboratory in 1955. The school was created to meet the international need for trained scientists and engineers, and its program was conducted jointly by Argonne National Laboratory, North Carolina State College, and Pennsylvania State University. Basic course work was presented at the universities in a 17-week program combining lecture with laboratory experience. More advanced work, including lectures and participation in design and laboratory projects, was given in a second 17-week program at the International School at Argonne. In 1960 the basic course work was discontinued, and the program was redirected to serve more advanced and experienced students from abroad. In recognition of the worldwide growth of programs and facilities to provide basic nuclear training at universities and laboratories, the program at Argonne was discontinued in 1964.

University programs

      In 1950 the first full-fledged nuclear engineering curriculum offered for college credit was established at North Carolina State College. By 1952 several schools had graduate programs in nuclear engineering. Most of these programs consisted of two or three courses, providing a background on reactor physics, reactor control, heat transfer, radiation effects, and shielding.

      With the support of the U.S. Atomic Energy Commission's Division of Nuclear Education and Training, the curricula and the number of schools in the United States continued to increase. By 1965, 61 schools were offering nuclear engineering programs. The programs had grown in diverse directions, however, and it became apparent that it was desirable to develop a consensus among educators about nuclear engineering education. To meet this need, a joint committee of the American Nuclear Society and the American Society of Engineering Education developed basic educational criteria. The committee members came from industry, national laboratories, and universities with nuclear engineering programs. The committee's “Report on Objective Criteria in Nuclear Engineering Education” had a major influence in shaping nuclear engineering curricula around the world and did much to establish nuclear engineering as a distinct discipline.

Nuclear engineering functions

      

● Research and development. Research and development entails the conception and development of new materials, processes, components, and systems for nuclear facilities and the development of analytical methods and experimental procedures for use in the development, analysis, design, and control of fission and fusion systems.

● Design. Another area of emphasis is the engineering design of such items as fuel elements, reactor-core supports, reflectors, thermal shields, biological shields, instrumentation and control systems, and safety systems.

● Fuel management. Fuel management involves specifying, procuring, and managing fuel throughout its reactor lifetime and beyond.

● Safety analysis. Normal and anticipated abnormal operating conditions must be considered in the analysis of the safety of a reactor or other facility using radioactive material. Hypothetical reactor accidents are analyzed to assess possible consequences and to devise means to prevent or mitigate these consequences.

● Operation and test. This function of nuclear engineering is concerned with the supervision and operation of nuclear power reactors and ancillary nuclear facilities.

      Nuclear engineers perform these functions for various kinds of employers: (1) architectural engineering firms, in which they handle design, safety analysis, project coordination, construction supervision, quality assurance, quality control, and related matters, (2) reactor vendors and other manufacturing organizations, in which they pursue research, development, design, manufacture, and installation of various components of nuclear systems, (3) electric utility companies, in which they handle planning, construction supervision, reactor-safety analysis, in-core nuclear fuel management, power-reactor economic analysis, environmental-impact assessment, personnel training, plant management, operation-shift supervision, radiation protection, spent-fuel storage, and radioactive-waste management, (4) regulatory agencies, in which they undertake licensing, rule making, safety research, risk analysis, on-site inspection, and research administration, (5) defense programs, in which they are employed in naval and nuclear weapons programs, (6) universities, in which they hold various faculty positions, and (7) national laboratories and industrial research laboratories, in which they carry out advanced research and development on a variety of nuclear programs in nuclear energy areas. Most of the advanced research and development on nuclear-related programs is conducted at national laboratories.

Branches of nuclear engineering

Nuclear power (nuclear energy)

      The greatest growth in the nuclear industry has been in the development of nuclear power plants. It is estimated that by the year 2000 one-third of all electric power generated worldwide will come from nuclear power plants.

      Nearly all commercial nuclear reactors in operation or under construction are thermal reactors. They are called thermal reactors because their fuel is fissioned by neutrons that have been slowed down by a moderator until they are in thermal equilibrium with the moderator. The boiling water reactor (BWR) and the pressurized water reactor (PWR) are the two predominant types of power reactors in use throughout the world. Both types are called light-water reactors (LWR). The water is used in these reactors as both moderator and coolant. In the BWR, steam is generated by direct boiling of water in the reactor core. In the PWR, steam is produced in an external steam generator rather than in the core, where the coolant under pressure is not allowed to boil. Other types of power reactors include graphite-moderated gas-cooled reactors in use in Great Britain and pressurized heavy-water reactors in Canada.

      A major advance in nuclear power is expected with the further development of the liquid-metal fast-breeder reactor (LMFBR). Programs are in progress in several countries to develop and deploy the LMFBR. (The reactor is cooled by a liquid metal, sodium, and fission is caused by fast neutrons. The reactor is called a breeder because it produces more nuclear fuel than it consumes.) Fuel in the breeder is utilized 60 times more effectively than that in light-water reactors. It is estimated that without the breeder the world supply of fissionable material for nuclear power plants could be consumed in a few decades. With the improved fuel utilization provided by the breeder, nuclear (nuclear fusion) power plants would be able to supply the world's electric energy requirement for centuries.

Fusion

      Fusion is a potential energy resource with a wide range of applications. The fusion process of combining two light atoms to form a heavier atom, with less mass than the two original atoms, is the basic energy process in the universe (i.e., fusion is the process that takes place in all stars). If fusion can be harnessed for terrestrial applications, the energy can be released in a variety of forms, including charged particles, electromagnetic radiation, and neutrons. Possible applications include electricity production, synthetic fuel production, process-heat applications, and fissile fuel production for fission reactors.

      Fusion research since about 1950 has concentrated on the issues of plasma physics, specifically the production of high-temperature plasmas (100,000,000° C [180,000,000° F] or greater) that can be confined at sufficiently high densities for sufficiently long times to produce net energy. Energy break-even conditions are expected to be demonstrated in several fusion devices in the late 20th century. Fusion physics research has made steady progress, and research efforts have begun to address the important engineering issues of fusion. Among the more important of these issues are those related to extracting useful energy from a plasma and developing complete fuel systems for fusion reactors. These areas are expected to receive increased research and development support in the future.

Naval nuclear propulsion

      The use of nuclear reactors to propel naval vessels has revolutionized naval operations throughout the world. The navies of Great Britain, France, China, the United States, Russia, and Ukraine are equipped with nuclear-powered ships, which are considered to be essential to the defense of their countries. Nuclear warships are capable of nearly unlimited high-speed operation without the need of fuel-oil support. In the 25 years following the maiden voyage of the Nautilus in 1954, the nuclear navy of the United States (United States Navy, The) steamed more than 80,000,000 kilometres (50,000,000 miles) throughout the oceans of the world, accumulating 25 centuries of reactor plant operation without any accidents involving a nuclear reactor. By the mid-1980s more than 40 percent of U.S. combat warships were nuclear-powered.

Nuclear weapons (nuclear weapon)

      Fission weapons (atomic bombs), fusion weapons (hydrogen bombs), and combination fission-fusion weapons are part of the world's nuclear arsenal. Nuclear engineers are employed on weapons programs in such diverse activities as research, development, design, fabrication, production, testing, maintenance, and surveillance of a large array of nuclear weapons systems.

      Efforts are in progress in the United States to develop, upgrade, and integrate weapons into warhead programs and to explore advanced concepts for future weapons systems. A concept of particular interest is inertial-confinement fusion. This program is directed at determining the feasibility of burning very small pellets of thermonuclear fuel using laser or particle-beam drivers. The program is of interest not only for applications to weapons physics but also for possible energy applications.

Radioisotopes (radioactive isotope)

      More than 500 radioisotopes are produced in nuclear reactors. The production, packaging, and application of these isotopes has become a large industry. They are used in heart pacemakers, medical research, sterilization of medical instruments, industrial tracers, X-ray equipment, curing of plastics, preservation of food, and as an energy source in electric generators. Perhaps the most important use of radioisotopes is in the field of medicine. They are used in procedures for half of all patients admitted to hospitals in the United States.

Nuclear-waste management

      Nuclear wastes can be classified in two groups, low-level and high-level. Low-level wastes come from nuclear power facilities, hospitals, and research institutions and include such items as contaminated clothing, wiping rags, tools, test tubes, needles, and other medical research materials. In the disposal of low-level wastes, the wastes are reduced in volume, then packaged in leak-proof containers, which are placed in an earth-covered trench in a low-level-waste disposal site. Such sites should be continuously monitored to detect any migration of radioactive material. High-level wastes are highly radioactive and derive from the chemical reprocessing of spent fuel elements and from the weapons program.

      By the late 20th century many countries were evaluating potential nuclear-waste disposal sites and developing terminal waste-storage technology. All these countries were preparing to handle high-level wastes. All had identified geologic formations that appeared to be technically feasible for repositories. In 1982 the U.S. Congress passed legislation establishing schedules for the selection, development, licensing, and construction of repositories for the safe, permanent storage of high-level waste.

Ira Bornstein Ed.

Additional Reading

Henry De Wolf Smyth, Atomic Energy for Military Purposes: The Official Report on the Development of the Atomic Bomb Under the Auspices of the United States Government, 1940–1945 (1945, reprinted 1989), on the U.S. development of the atomic bomb, is commonly known as the Smyth report and was issued by the Manhattan District of the U.S. Corps of Engineers. Richard G. Hewlett and Francis Duncan, Nuclear Navy, 1946–1962 (1974), serves as a historical and analytical study. C. Larson and D. Duffy, Historical Perspectives: Dawn of the Nuclear Age (1989), is another useful source of historical information. Glenn T. Seaborg and William R. Corliss, Man and Atom (1971), explores peaceful applications of nuclear energy. Samuel Glasstone and Alexander Sesonske, Nuclear Reactor Engineering, 3rd ed. (1981), serves as a basic work for nuclear engineering education. Manson Benedict, Thomas H. Pigford, and Hans Wolfgang Levi, Nuclear Chemical Engineering, 2nd ed. (1981), stands as a comprehensive work that emphasizes nuclear processing and includes useful information on metallurgy. K. Almenas and R. Lee, Nuclear Engineering: An Introduction (1992), is also of interest. Raymond L. Murray, Nuclear Energy, 4th ed. (1993), serves as an introduction to basic nuclear processes.Ira Bornstein Ed.

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