The Atomic Energy Control Board, a Canadian government agency, regulates Canada’s nuclear energy industry. The board’s duties resemble those of the Nuclear Regulatory Commission.
Careers in nuclear energy cover a wide range of occupations and require widely varying amounts of training. A high percentage of the jobs require a college degree or extensive technical education. Many of these jobs are in large research laboratories, which work to improve nuclear processes and to lessen their hazards. Other careers requiring advanced training are in such areas as uranium mining and processing, reactor manufacturing and inspection, power plant operation, and government regulation.
In 1972, scientists discovered that a natural chain reaction had released nuclear energy nearly 2 billion years ago in a uranium deposit in west-central Africa. Two billion years ago, there had been so little radioactive decay that the ore contained enough U-235 for a chain reaction. An accumulation of ground water acted as a moderator to begin the reaction. As heat from the reaction changed the water into steam, less and less water was available to serve as a moderator and the reaction died out. Except for such rare natural occurrences, nuclear energy was not released on a large scale on the earth until 1942. That year, scientists produced the first artificially created chain reaction. Scientific discoveries that took place within the last 100 years led to the large-scale release of nuclear energy.
Early developments
Before the late 1800’s, scientists did not suspect that atoms could release nuclear energy. Then in 1896, the French physicist Antoine Henri Becquerel found that uranium constantly gives off energy in the form of invisible rays. He thus became the discoverer of radioactivity. Other scientists soon began experiments to learn more about this mysterious phenomenon.
The beginning of nuclear physics. In 1898, the great British physicist Ernest Rutherford identified two kinds of radioactive “rays,” which he called alpha rays and beta rays. He and other researchers later showed that these rays are actually high-energy particles, which became known as alpha and beta particles. Experiments with these particles then led Rutherford to discover the atom’s nucleus. This achievement, which Rutherford announced in 1911, marked the beginning of a new science–nuclear physics.
About 1914, scientists began doing experiments to see what happens when nuclear particles collide. The experimenters used alpha particles from naturally radioactive materials to bombard the nuclei of light atoms. Light nuclei do not repel positively charged particles, such as alpha particles, as strongly as heavy nuclei do. Rutherford used this method to produce the first artificial transmutations in a series of experiments from 1917 to 1919. He bombarded nitrogen atoms with alpha particles. In rare collisions, a nitrogen 14 nucleus absorbed an alpha particle (a helium 4 nucleus). At the same time, the alpha particle pushed a proton out of the nitrogen nucleus. The nucleus thereby became an oxygen 17 nucleus.
Artificial fission. To produce nuclear reactions in heavy nuclei, scientists needed a particle that heavy nuclei would not repel. In 1932, the British physicist James Chadwick discovered such a particle–the neutron. In 1938, two German radiochemists, Otto Hahn and Fritz Strassmann, reported they had produced the element barium by bombarding uranium with neutrons.
At first, scientists could not explain how uranium had produced barium, which is much lighter than uranium. All previous transmutations had resulted in an element about as heavy as the original one. Then in 1939, the Austrian physicist Lise Meitner and her nephew Otto Frisch showed that Hahn and Strassman had in fact produced the first known artificial fission reaction. A uranium nucleus had split into two nearly equal fragments, one of which consisted of a barium nucleus. Two neutrons were also emitted. The other fragment consisted of a nucleus of krypton, a somewhat lighter element than barium. These two nuclei, together with the emitted neutrons, are lighter than a uranium nucleus and a neutron. The reaction had therefore produced more energy than it consumed.
Scientists soon realized that if many uranium nuclei could be made to fission, a tremendous amount of energy would be released. The amount of energy could be calculated from a theory developed by the great German-born physicist Albert Einstein in 1905. The theory shows that matter can change into energy and that matter and energy are related by the equation E equals m times c-squared. This equation states that the energy (E) into which a given amount of matter can change equals the mass (m) of that matter multiplied by the speed of light squared (c-squared). The speed of light squared is obtained by multiplying the speed of light by itself. Using this equation, scientists determined that the fissioning of 1 pound (0.45 kilogram) of uranium would release as much energy as 8,000 short tons (7,300 metric tons) of TNT. Uranium could therefore be used to make a powerful bomb.
The beginning of the nuclear age
The development of nuclear weapons. World War II broke out in Europe in September 1939. The month before, Einstein had written to U.S. President Franklin D. Roosevelt urging him to commit the United States to developing an atomic bomb. Einstein had fled to the United States from Germany to escape Nazi persecution. He warned Roosevelt that German scientists might already be working on a nuclear bomb. Roosevelt acted on Einstein’s urging, and early in 1940 scientists received the first funds for uranium research in the United States. The United States entered World War II in 1941. The government then ordered an all-out effort to build an atomic bomb and in 1942 established the top-secret Manhattan Project to achieve this goal.
A group of scientists at the University of Chicago had charge of producing plutonium for the Manhattan Project. The group included such noted physicists as Enrico Fermi, Leo Szilard, and Eugene Wigner, all of whom had been born in Europe and had settled in the United States. Fermi headed the group. Under the scientists’ direction, workers built an atomic pile, or reactor, beneath the stands of the university athletic field. The pile consisted of 50 short tons (45 metric tons) of natural uranium oxide and uranium embedded in 500 short tons (450 metric tons) of graphite. The graphite served as a moderator. The pile was designed to demonstrate a controlled nuclear chain reaction in the uranium. Cadmium rods controlled the reaction. On Dec. 2, 1942, this reactor produced the first artificial chain reaction.
The success of the University of Chicago project led the U.S. government to build a plutonium-producing plant in Hanford, Wash. The government also built a uranium enrichment plant in Oak Ridge, Tenn. Plutonium and greatly enriched uranium from these plants were used in the two atomic bombs that the United States dropped on Japan in August 1945.
After World War II, scientists began work on developing a hydrogen bomb. The United States exploded the first hydrogen bomb in 1952 and so achieved the world’s first large-scale thermonuclear reaction But the AEC became responsible for regulating the nuclear energy industry. It also kept control in such areas as uranium enrichment and waste disposal.
The United States made the world’s first full-scale use of controlled nuclear energy in 1954. That year, the U.S. Navy launched the first nuclear-powered vessel, the submarine Nautilus. The world’s first full-scale nuclear power plant began operations in 1956 at Calder Hall in northwestern England. In 1957, the first large-scale nuclear plant in the United States opened in Shippingport, Pa. It supplied electricity to the Pittsburgh area until 1982, when the plant was closed. Canada opened its first full-scale plant in 1962 at Rolphton, Ont.
The successful start of the nuclear power industry convinced world leaders of the need for international cooperation in the field. In 1957, the United Nations (UN) established the International Atomic Energy Agency to promote the peaceful uses of nuclear energy. Also in 1957, Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany formed the European Atomic Energy Community (Euratom). The organization encourages the development of nuclear power among its member countries. Denmark, the United Kingdom, and Ireland joined Euratom in 1973.
The spread of nuclear capability
During the 1960’s and early 1970’s, a number of countries acquired reactors and used them to start nuclear power development. Progress was also made during this period toward limiting nuclear weapons tests and stopping the spread of nuclear weapons. In 1970, for example, a nuclear nonproliferation treaty went into effect. The treaty prohibits the nuclear powers that have agreed to abide by the document from giving nuclear weapons to nations that do not already have them. The nonproliferation treaty also prohibits nations without nuclear weapons from acquiring them.
But the nonproliferation treaty does not prohibit nations from selling or buying nuclear reactors. A reactor can be used not only for peaceful purposes but also to produce plutonium for nuclear weapons. India used a research reactor for this purpose and in 1974 exploded its first atomic bomb. Canada had supplied the reactor to India with the understanding it would be used for peaceful purposes only. Canada has signed the nonproliferation treaty, but India has not. Critics of India’s action question the wisdom of supplying reactors to countries that do not already have them.
Meanwhile, the United States had been greatly increasing its nuclear power capacity. But opposition to nuclear power development also increased in the United States during the late 1960’s and early 1970’s. Critics began to question nearly every aspect of nuclear power production, from the cost of uranium enrichment to the problems of waste disposal.
Many critics of the United States nuclear program charged that the government overlooked various safety risks at nuclear plants to promote nuclear power development. Partly as a result of such criticism, Congress disbanded the Atomic Energy Commission (AEC) in 1974 and divided its functions between two newly formed agencies. The Energy Research and Development Administration (ERDA) took over the AEC’s development programs. The Nuclear Regulatory Commission (NRC) took over its regulatory duties. The NRC, it was believed, could better regulate the industry if it was not also responsible for the industry’s growth and development. In 1977, Congress abolished ERDA and transferred its responsibilities to the newly created Department of Energy.
Safety concerns
There have been a number of accidents at nuclear power plants. Most of them have not been serious. However, in 1957, a fire at the Windscale plutonium production plant in northern England resulted in the release of a large quantity of radioactivity. The British government banned the sale of milk from cows in that part of England for more than a month after the fire.
In the United States, concerns about the safety of nuclear reactors increased after a serious accident in 1979 at the Three Mile Island nuclear power plant near Harrisburg, Pennsylvania. Mechanical and human failures resulted in a breakdown of the reactor’s cooling system and the destruction of the reactor core. Scientists and technicians prevented a failure of the reactor vessel that might have released large amounts of radioactive isotopes into the reactor containment building. Cleanup of the plant was completed in the early 1990’s.
The worst nuclear accident in history occurred in 1986 at the Chernobyl nuclear power plant near Kiev in Ukraine, which was then part of the Soviet Union. An explosion and fire ripped apart the reactor and released large amounts of radioactive isotopes into the atmosphere. Unlike most Western reactors, the Chernobyl reactors lacked an enclosure to prevent radioactive isotopes from escaping. Soviet officials reported that 31 people died from radiation sickness or burns and more than 200 others were seriously injured. The radioactive substances spread over parts of what are now Ukraine, Russia, and Belarus, and were carried by wind into northern and central Europe. Experts expected a significant increase in the number of cancer deaths among those near the reactor. But they predicted that the health effects outside the Chernobyl area would be slight.
As a result of the accidents at Three Mile Island and Chernobyl, opposition to nuclear power increased in many countries during the late 1980’s. In the United States, the NRC tightened its control of nuclear plants.
Experts have expressed particular concern over the safety of older Soviet-designed reactors now operating in Russia, Ukraine, and several countries of the former Soviet bloc. Western scientists and engineers are helping to remedy some of the most urgent safety problems in these reactors.
As the nuclear power industry has continued to develop, many improvements in plant equipment and operation have increased safety. Nonetheless, some experts insist that the next generation of reactors should take greater advantage of design features that rely less–or not at all–on mechanical equipment such as pumps and valves to remove heat if an accident occurs. Some of these reactors are known as passively safe reactors.