Queen Elizabeth II switched power into Great Britain’s national grid from Calder Hall, the world’s first large-scale nuclear power station.
The development of nuclear power in Great Britain after World War II was limited by the lack of means for enriching uranium, so primary emphasis was given to producing plutonium. In the late 1940’s, two research reactors were built at Harwell, England. The Graphite Low Energy Experimental Pile (GLEEP) had a thirty-three-ton core of natural uranium and 550 tons of graphite moderator cooled by forced air. The British Experimental Pile (BEPO) contained forty tons of natural uranium and six hundred tons of graphite, also with forced-air cooling. These were followed by two production reactors at Sellafield on the Cumbria coast in England, which were designed to produce plutonium. They used natural uranium clad in aluminum, lying in horizontal channels in a graphite core cooled by forced air. In 1947, the site was renamed “Windscale.”
In 1954, the United Kingdom Atomic Energy Authority
The heart of the Calder Hall reactors was a welded-steel pressure vessel some five centimeters thick enclosing a graphite moderator, a twenty-four-sided regular prism about eleven meters across and eight meters high. The fuel elements were solid rods of natural uranium one meter in length and about three centimeters in diameter, encased in a can made of a magnesium alloy called magnox, which separated the uranium from the coolant and provided extended finned surfaces for heat transfer. The magnox casing, which absorbed fewer neutrons than aluminum and was less susceptible to corrosion in the core, was used in an entire family of reactors called magnox reactors. Each channel in the moderator was designed for six fuel elements, and the complete charge formed a supercritical mass of 130 tons. The control rods, made of boron steel clad with stainless steel, entered the core through the pressure-vessel head. They were held by electromagnets for quick release in an emergency. The entire pressure vessel was enclosed in a biological shield of concrete more than two meters thick to reduce neutron radiation to a low level.
In 1958, Hinton became the chairman of the Central Electricity Generating Board (CEGB) of Great Britain. Under his leadership, eight magnox nuclear power stations, each with two identical reactors, were built for the CEGB, and one was built for the South of Scotland Electricity Board. The Calder Hall magnox design was primarily intended for plutonium production, and the reactors had to be shut down for refueling. Design details of subsequent stations varied, but with increasing power output. All the subsequent stations could be refueled without interrupting the operation of the reactor. The intensely radioactive irradiated fuel was moved inside a discharge machine and dropped into a “cooling pond,” which served to shield and cool the fuel while the short-lived fission products decay. After about 150 days, the fuel was transported to Windscale for reprocessing.
The nuclear fuel reprocessing plant was a chemical plant for the separation of highly radioactive materials. Once in operation, it became contaminated by radioactivity, and all operations had to be carried on by remote control behind heavy shielding. Few mechanical parts were used in the process line, because any malfunction would require months or even years of decontamination before it could be repaired. In the reprocessing plant, the magnox cladding was stripped and stored indefinitely, while the spent fuel was dropped into nitric acid. The acid was mixed with an organic solvent called Butex that absorbed the uranium and plutonium, leaving behind 99.96 percent of the fission products in the acid. The uranium could then be separated from the plutonium by various chemical processes, and these could then be made into fresh fuel elements or weapons. Radioactive waste
High-level waste dissolved in the nitric acid of the first-stage separation posed the greatest problem of waste disposal. At Windscale, the reprocessing of one ton of fuel produced about five cubic meters of high-level waste. This volume was reduced by evaporation and then stored in a concrete building containing an array of special storage tanks. Gradual evaporation of the water from the solution was accompanied by gradual decrease of the radioactive heat output, but within the first two decades of operation, about six hundred cubic meters of liquid waste accumulated at Windscale. Similar tank storage installations proliferated in other countries with nuclear reprocessing facilities, but none gained more notoriety than the one at Hanford,
Release of radioactivity from nuclear power plants poses another problem, in terms of both routine release and accidental release. Neutrons that escape from the pressure vessel of some reactors are vented with air from a stack atop the reactor building. Some nuclei in the air absorb neutrons and become radioactive. Most notable of these radioactive products is argon 41, which has a half-life of 1.8 hours, meaning that most of it decays to a low level of activity before drifting to ground level. Accidental releases are much less frequent but can be much more dangerous.
The first such accident in Great Britain occurred in the Windscale
In 1971, UKAEA broke into a research arm and a production arm, the later named British Nuclear Fuels Limited (BNFL), which took charge of the major part of the Windscale works. In 1981, the Windscale and Calder works were renamed Sellafield, with the UKAEA portion of Windscale remaining under the Windscale name. In the 1990’s, plans to disassemble and clean up the nuclear piles began to be implemented. In 2005, the Nuclear Decommisioning Authority assumed ownership of the Sellafield site. Along with other facilities at the site is the Sellafield Visitors’ Centre, which conducts workshops, exhibits, immersion cinema, and other educational activities aimed at provoking public debate about nuclear power and energy policy.
Although originally built to produce weapons-grade plutonium, Calder Hall became the first commercial nuclear power plant in the world, producing 180 megawatts. As such, it introduced a new, if somewhat tenuous, source of commercial energy to the world.
Nuclear power remains both controversial and promising: As late as April, 2005, for example, a leak was discovered at the Thorp
Nevertheless, nuclear power also promises a relatively unlimited supply of cheap energy that emits no greenhouse gases and thus does not contribute to air pollution and global warming, unlike the more conventional fossil fuels (coal and oil) used for much of the world’s energy. In addition to the dangers they pose to the environment, fossil fuels will eventually be depleted, whereas nuclear energy offers a nearly limitless supply.
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Blair, Ian. Taming the Atom: Facing the Future with Nuclear Power. Bristol, England: Adam Hilger, 1983. A readable account of nuclear power from a British advocate, including basic principles, the nuclear industry, and an appendix of reactor data. -
Bolter, Harold. Inside Sellafield. London: Quartet Books, 1996. A history of the site from the early years to privitization, by the longest-serving director of BNFL, the site’s owner. -
Kenny, Colum. Fearing Sellafield: What It Is and Why the Irish Want It Shut. Dublin: Gill & Macmillan, 2003. Examines the Irish fear of Sellafield, particularly in the light of the September 11, 2001, terrorist attacks. Why, the author asks, is Britain reprocessing nuclear fuel when there are no new nuclear power plants in the pipeline? Both a history of the site and an examination of government policy in the light of Anglo-Irish relations. Includes bibliographical references and index. -
Patterson, Walter C. Nuclear Power. Baltimore: Penguin Books, 1976. A good introduction to the early development of nuclear power from a British perspective. Includes descriptions of reactors, the nuclear fuel cycle, and nuclear accidents. -
Sagan, Leonard A., ed. Human and Ecologic Effects of Nuclear Power. Springfield, Ill.: Charles C Thomas, 1974. An authoritative source, with chapters by experts in the management of radioactivity and the ecologic effects of nuclear reactors. Diagrams, tables, and references. -
Tagami, Keiko.“Technetium-99 Behaviour in the Terrestrial Environment: Field Observations and Radiotracer Experiments.” Journal of Nuclear and Radiochemical Sciences 4, no. 1 (2003): A1-A8. Reports on researching concerning the environmental impact of the radioactive waste technetium 99 on the environment. -
Webb, G. A. M., et al.“Classification of Events with an Off-Site Radiological Impact at the Sellafield Site Between 1950 and 2000, Using the International Nuclear Event Scale.” Journal of Radiological Protection 26 (March, 2006). Identifies nuclear leaks at the site and rates them according to the International Nuclear Event Scale.
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