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Nuclear power
On the 20th of December 1951, four ordinary light bulbs flickered to life in a quiet field near Arco, Idaho, powered by a machine that had never been seen before. This was the Experimental Breeder Reactor One, and it marked the moment humanity first harnessed the atom to generate electricity. The reactor produced about 100 kilowatts of power, enough to illuminate a small town, but the significance extended far beyond the immediate glow. It was the culmination of decades of research into radioactivity and the discovery of nuclear fission in 1938. Scientists realized that neutrons released by a splitting nucleus could trigger a self-sustaining chain reaction, a concept confirmed experimentally in 1939. This discovery occurred on the cusp of World War II, leading scientists to petition governments for support to develop nuclear weapons. The United States responded by creating the Chicago Pile-1 under the Stagg Field stadium at the University of Chicago, which achieved criticality on the 2nd of December 1942. This reactor was part of the Manhattan Project, the Allied effort to create atomic bombs. The military nature of these early devices did not dampen the optimism of the 1940s and 1950s that nuclear power could provide cheap and endless energy. President Dwight Eisenhower gave his Atoms for Peace speech at the United Nations in 1953, emphasizing the need to develop peaceful uses of nuclear power quickly. This was followed by the Atomic Energy Act of 1954, which allowed rapid declassification of U.S. reactor technology and encouraged development by the private sector. The first organization to develop practical nuclear power was the U.S. Navy, with the S1W reactor for the purpose of propelling submarines and aircraft carriers. The first nuclear-powered submarine, the USS Nautilus, was put to sea in January 1954. The S1W reactor was a pressurized water reactor, a design chosen because it was simpler, more compact, and easier to operate compared to alternative designs. This decision would result in the PWR being the reactor of choice also for power generation, thus having a lasting impact on the civilian electricity market in the years to come.
The Grid And The Crisis
The world's first nuclear power plant to generate electricity for a power grid was the Obninsk Nuclear Power Plant in the USSR, which went online on the 27th of June 1954, producing around 5 megawatts of electric power. The world's first commercial nuclear power station, Calder Hall at Windscale, England, was connected to the national power grid on the 27th of August 1956. In common with a number of other generation I reactors, the plant had the dual purpose of producing electricity and plutonium-239, the latter for the nascent nuclear weapons program in Britain. The total global installed nuclear capacity initially rose relatively quickly, rising from less than 1 gigawatt in 1960 to 100 gigawatts in the late 1970s. During the 1970s and 1980s rising economic costs and falling fossil fuel prices made nuclear power plants then under construction less attractive. In the 1980s in the U.S. and 1990s in Europe electricity liberalization made investment in new nuclear power plants less desirable than natural gas plants. The 1973 oil crisis had a significant effect on countries, such as France and Japan, which had relied more heavily on oil for electric generation to invest in nuclear power. France would construct 25 nuclear power plants over the next 15 years, and as of 2019, 71% of French electricity was generated by nuclear power, the highest percentage for any nation in the world. Some local opposition to nuclear power emerged in the United States in the early 1960s. In the late 1960s, some members of the scientific community began to express pointed concerns. These anti-nuclear concerns related to nuclear accidents, nuclear proliferation, nuclear terrorism and radioactive waste disposal. In the early 1970s, there were large protests about a proposed nuclear power plant in Wyhl, Germany. The project was cancelled in 1975. The anti-nuclear success at Wyhl inspired opposition to nuclear power in other parts of Europe and North America. By the mid-1970s anti-nuclear activism gained a wider appeal and influence, and nuclear power started to become an issue of major public protest. In some countries, the nuclear power debate reached an intensity unprecedented in the history of technology controversies. The increased public hostility to nuclear power led to a longer license procurement process, more regulations and increased requirements for safety equipment, which made new construction much more expensive. In the United States, over 120 reactor proposals were ultimately cancelled and the construction of new reactors ground to a halt. The 1979 accident at Three Mile Island played a major part in the reduction in the number of new plant constructions in many countries.
Common questions
When did the Experimental Breeder Reactor One generate electricity for the first time?
The Experimental Breeder Reactor One generated electricity for the first time on the 20th of December 1951. This event occurred in a quiet field near Arco, Idaho, and marked the moment humanity first harnessed the atom to generate electricity. The reactor produced about 100 kilowatts of power to illuminate four ordinary light bulbs.
Which country built the world's first nuclear power plant to generate electricity for a power grid?
The USSR built the world's first nuclear power plant to generate electricity for a power grid. The Obninsk Nuclear Power Plant went online on the 27th of June 1954 and produced around 5 megawatts of electric power. This plant preceded the first commercial nuclear power station, Calder Hall, which connected to the national power grid in England on the 27th of August 1956.
What percentage of French electricity was generated by nuclear power as of 2019?
As of 2019, 71% of French electricity was generated by nuclear power. This percentage represents the highest share for any nation in the world. France constructed 25 nuclear power plants over the 15 years following the 1973 oil crisis to reduce reliance on oil for electric generation.
How many direct deaths occurred during the 1986 Chernobyl disaster in the USSR?
The 1986 Chernobyl disaster in the USSR resulted in 56 direct deaths. This event is considered the worst nuclear disaster in history both in total casualties and financially, with cleanup costs estimated at 68 billion U.S. dollars in 2019 adjusted for inflation. The disaster led to the creation of the World Association of Nuclear Operators to promote safety awareness.
What is the half-life of reactor-grade plutonium found in spent nuclear fuel?
The half-life of reactor-grade plutonium found in spent nuclear fuel is 24,000 years. This isotope is one of the medium-lived transuranic elements that pose the most concern for countries that do not reprocess spent fuel. Spent fuel becomes less radioactive than natural uranium ore after about 100,000 years.
Which nuclear accident was ranked at level 7 on the International Nuclear Event Scale?
The Chernobyl accident and the Fukushima accident were both ranked at level 7 on the International Nuclear Event Scale. The Fukushima Daiichi nuclear accident was caused by the 2011 Tohoku earthquake and tsunami and resulted in three core meltdowns. These two events are the only level 7 accidents in the civilian nuclear power industry.
During the 1980s one new nuclear reactor started up every 17 days on average. By the end of the decade, global installed nuclear capacity reached 300 gigawatts. Since the late 1980s, new capacity additions slowed significantly, with the installed nuclear capacity reaching 365 gigawatts in 2005. The 1986 Chernobyl disaster in the USSR, involving an RBMK reactor, altered the development of nuclear power and led to a greater focus on meeting international safety and regulatory standards. It is considered the worst nuclear disaster in history both in total casualties, with 56 direct deaths, and financially, with the cleanup and the cost estimated at 18 billion rubles, which equates to 68 billion U.S. dollars in 2019 adjusted for inflation. The international organization to promote safety awareness and the professional development of operators in nuclear facilities, the World Association of Nuclear Operators, was created as a direct outcome of the 1986 Chernobyl accident. The Chernobyl disaster played a major part in the reduction in the number of new plant constructions in the following years. Influenced by these events, Italy voted against nuclear power in a 1987 referendum, becoming the first major economy to completely phase out nuclear power in 1990. The 2011 Fukushima Daiichi nuclear accident was caused by the Tōhoku earthquake and tsunami, one of the largest earthquakes ever recorded. The Fukushima Daiichi Nuclear Power Plant suffered three core meltdowns due to failure of the emergency cooling system for lack of electricity supply. This resulted in the most serious civilian nuclear accident since the 1986 Chernobyl disaster. The accident prompted a re-examination of nuclear safety and nuclear energy policy in many countries. Germany approved plans to close all its reactors by 2022, and many other countries reviewed their nuclear power programs. Following the disaster, Japan shut down all of its nuclear power reactors, some of them permanently, and in 2015 began a gradual process to restart the remaining 40 reactors, following safety checks and based on revised criteria for operations and public approval. In 2022, the Japanese government, under the leadership of Prime Minister Fumio Kishida, declared that 10 more nuclear power plants were to be reopened since the 2011 disaster. Kishida is also pushing for research and construction of new safer nuclear plants to safeguard Japanese consumers from the fluctuating price of the fossil fuel market and reduce Japan's greenhouse gas emissions. Kishida intends to have Japan become a significant exporter of nuclear energy and technology to developing countries around the world.
The Fuel Cycle
The life cycle of nuclear fuel starts with uranium mining. The uranium ore is then converted into a compact ore concentrate form, known as yellowcake, to facilitate transport. Fission reactors generally need uranium-235, a fissile isotope of uranium. The concentration of uranium-235 in natural uranium is low, about 0.7%. Some reactors can use this natural uranium as fuel, depending on their neutron economy. These reactors generally have graphite or heavy water moderators. For light water reactors, the most common type of reactor, this concentration is too low, and it must be increased by a process called uranium enrichment. In civilian light water reactors, uranium is typically enriched to 3.55% uranium-235. The uranium is then generally converted into uranium oxide, a ceramic, that is then compressively sintered into fuel pellets, a stack of which forms fuel rods of the proper composition and geometry for the particular reactor. After some time in the reactor, the fuel will have reduced fissile material and increased fission products, until its use becomes impractical. At this point, the spent fuel will be moved to a spent fuel pool which provides cooling for the thermal heat and shielding for ionizing radiation. After several months or years, the spent fuel is radioactively and thermally cool enough to be moved to dry storage casks or reprocessed. Uranium is a fairly common element in the Earth's crust, approximately as common as tin or germanium, and is about 40 times more common than silver. As of 2011 the world's known resources of uranium, economically recoverable at the arbitrary price ceiling of 130 U.S. dollars per kilogram, were enough to last for between 70 and 100 years in current reactors. Light water reactors make relatively inefficient use of nuclear fuel, mostly using only the very rare uranium-235 isotope. Limited uranium-235 supply may inhibit substantial expansion with the current nuclear technology. Nuclear reprocessing can make this waste reusable, and newer reactors also achieve a more efficient use of the available resources than older ones. More advanced nuclear reactor technologies, such as fast reactors, can use much more of the natural uranium, use current nuclear waste as fuel, as well as creating new fuel out of non-fissile material. With a pure fast reactor fuel cycle with a burn up of all the uranium and actinides, there is an estimated 160,000 years worth of uranium in total conventional resources and phosphate ore at the price of 60 to 100 U.S. dollars per kilogram. Unconventional uranium resources also exist. Uranium is naturally present in seawater at a concentration of about 3 micrograms per liter, with 4.4 billion tons of uranium considered present in seawater at any time. In 2014 it was suggested that it would be economically competitive to produce nuclear fuel from seawater if the process was implemented at large scale. Over geological timescales, uranium extracted on an industrial scale from seawater would be replenished by both river erosion of rocks and the natural process of uranium dissolved from the surface area of the ocean floor, both of which maintain the solubility equilibria of seawater concentration at a stable level.
The Waste Question
The most important waste stream from nuclear power reactors is spent nuclear fuel, which is considered high-level waste. For light water reactors, spent fuel is typically composed of 95% uranium, 4% fission products, and about 1% transuranic actinides. The fission products are responsible for the bulk of the short-term radioactivity, whereas the plutonium and other transuranics are responsible for the bulk of the long-term radioactivity. High-level waste must be stored isolated from the biosphere with sufficient shielding so as to limit radiation exposure. After being removed from the reactors, used fuel bundles are stored for six to ten years in spent fuel pools, which provide cooling and shielding against radiation. After that, the fuel is cool enough that it can be safely transferred to dry cask storage. The radioactivity decreases exponentially with time, such that it will have decreased by 99.5% after 100 years. The more intensely radioactive short-lived fission products decay into stable elements in approximately 300 years, and after about 100,000 years, the spent fuel becomes less radioactive than natural uranium ore. Commonly suggested methods to isolate long-lived fission product waste from the biosphere include separation and transmutation, synroc treatments, or deep geological storage. Thermal-neutron reactors, which presently constitute the majority of the world fleet, cannot burn up the reactor grade plutonium that is generated during the reactor operation. This limits the life of nuclear fuel to a few years. In some countries, such as the United States, spent fuel is classified in its entirety as a nuclear waste. In other countries, such as France, it is largely reprocessed to produce a partially recycled fuel, known as mixed oxide fuel or MOX. For spent fuel that does not undergo reprocessing, the most concerning isotopes are the medium-lived transuranic elements, which are led by reactor-grade plutonium with a half-life of 24,000 years. Some proposed reactor designs, such as the integral fast reactor and molten salt reactors, can use as fuel the plutonium and other actinides in spent fuel from light water reactors, thanks to their fast fission spectrum. This offers a potentially more attractive alternative to deep geological disposal. The thorium fuel cycle results in similar fission products, though creates a much smaller proportion of transuranic elements from neutron capture events within a reactor. Spent thorium fuel, although more difficult to handle than spent uranium fuel, may present somewhat lower proliferation risks. The nuclear industry also produces a large volume of low-level waste, with low radioactivity, in the form of contaminated items like clothing, hand tools, water purifier resins, and the materials of which the reactor itself is built upon decommissioning. Low-level waste can be stored on-site until radiation levels are low enough to be disposed of as ordinary waste, or it can be sent to a low-level waste disposal site. In countries with nuclear power, radioactive wastes account for less than 1% of total industrial toxic wastes, much of which remains hazardous for long periods. Overall, nuclear power produces far less waste material by volume than fossil-fuel based power plants. Coal-burning plants, in particular, produce large amounts of toxic and mildly radioactive ash resulting from the concentration of naturally occurring radioactive materials in coal. A 2008 report from Oak Ridge National Laboratory concluded that coal power actually results in more radioactivity being released into the environment than nuclear power operation, and that the population effective dose equivalent from radiation from coal plants is 100 times that from the operation of nuclear plants. Although coal ash is much less radioactive than spent nuclear fuel by weight, coal ash is produced in much higher quantities per unit of energy generated. It is also released directly into the environment as fly ash, whereas nuclear plants use shielding to protect the environment from radioactive materials. Nuclear waste volume is small compared to the energy produced. For example, at Yankee Rowe Nuclear Power Station, which generated 44 billion kilowatt hours of electricity when in service, its complete spent fuel inventory is contained within sixteen casks. It is estimated that to produce a lifetime supply of energy for a person at a western standard of living, approximately 3 gigawatt hours, would require on the order of the volume of a soda can of low enriched uranium, resulting in a similar volume of spent fuel generated. Disposal of nuclear waste is often considered the most politically divisive aspect in the lifecycle of a nuclear power facility. There is an international consensus on the advisability of storing nuclear waste in deep geological repositories. With the advent of new technologies, other methods including horizontal drillhole disposal into geologically inactive areas have been proposed. There are no commercial scale purpose built underground high-level waste repositories in operation. However, in Finland the Onkalo spent nuclear fuel repository of the Olkiluoto Nuclear Power Plant was under construction as of 2015.
The Safety Record
Nuclear power plants have three unique characteristics that affect their safety, as compared to other power plants. Firstly, intensely radioactive materials are present in a nuclear reactor. Their release to the environment could be hazardous. Secondly, the fission products, which make up most of the intensely radioactive substances in the reactor, continue to generate a significant amount of decay heat even after the fission chain reaction has stopped. If the heat cannot be removed from the reactor, the fuel rods may overheat and release radioactive materials. Thirdly, a criticality accident is possible in certain reactor designs if the chain reaction cannot be controlled. These three characteristics have to be taken into account when designing nuclear reactors. All modern reactors are designed so that an uncontrolled increase of the reactor power is prevented by natural feedback mechanisms, a concept known as negative void coefficient of reactivity. If the temperature or the amount of steam in the reactor increases, the fission rate inherently decreases. The chain reaction can also be manually stopped by inserting control rods into the reactor core. Emergency core cooling systems can remove the decay heat from the reactor if normal cooling systems fail. If the ECCS fails, multiple physical barriers limit the release of radioactive materials to the environment even in the case of an accident. The last physical barrier is the large containment building. With a death rate of 0.03 per terawatt hour, nuclear power is the second safest energy source per unit of energy generated, after solar power, in terms of mortality when the historical track-record is considered. Energy produced by coal, petroleum, natural gas and hydropower has caused more deaths per unit of energy generated due to air pollution and energy accidents. This is found when comparing the immediate deaths from other energy sources to both the immediate and the latent, or predicted, indirect cancer deaths from nuclear energy accidents. When the direct and indirect fatalities from nuclear power and fossil fuels are compared, the use of nuclear power has been calculated to have prevented about 1.84 million deaths from air pollution between 1971 and 2009, by reducing the proportion of energy that would otherwise have been generated by fossil fuels. Following the 2011 Fukushima nuclear disaster, it has been estimated that if Japan had never adopted nuclear power, accidents and pollution from coal or gas plants would have caused more lost years of life. Serious impacts of nuclear accidents are often not directly attributable to radiation exposure, but rather social and psychological effects. Evacuation and long-term displacement of affected populations created problems for many people, especially the elderly and hospital patients. Forced evacuation from a nuclear accident may lead to social isolation, anxiety, depression, psychosomatic medical problems, reckless behavior, and suicide. A comprehensive 2005 study on the aftermath of the Chernobyl disaster concluded that the mental health impact is the largest public health problem caused by the accident. Frank N. von Hippel, an American scientist, commented that a disproportionate fear of ionizing radiation could have long-term psychological effects on the population of contaminated areas following the Fukushima disaster. The severity of nuclear accidents is generally classified using the International Nuclear Event Scale introduced by the International Atomic Energy Agency. The scale ranks anomalous events or accidents on a scale from 0 to 7. There have been three accidents of level 5 or higher in the civilian nuclear power industry, two of which, the Chernobyl accident and the Fukushima accident, are ranked at level 7. The first major nuclear accidents were the Kyshtym disaster in the Soviet Union and the Windscale fire in the United Kingdom, both in 1957. The first major accident at a nuclear reactor in the USA occurred in 1961 at the SL-1, a U.S. Army experimental nuclear power reactor at the Idaho National Laboratory. An uncontrolled chain reaction resulted in a steam explosion which killed the three crew members and caused a meltdown. Another serious accident happened in 1968, when one of the two liquid-metal-cooled reactors on board the Soviet submarine K-429 underwent a fuel element failure, with the emission of gaseous fission products into the surrounding air, resulting in 9 crew fatalities and 83 injuries. The Fukushima Daiichi nuclear accident was caused by the 2011 Tohoku earthquake and tsunami. The accident has not caused any radiation-related deaths but resulted in radioactive contamination of surrounding areas. The difficult cleanup operation is expected to cost tens of billions of dollars over 40 or more years. The Three Mile Island accident in 1979 was a smaller scale accident, rated at INES level 5. There were no direct or indirect deaths caused by the accident. The impact of nuclear accidents is controversial. According to Benjamin K. Sovacool, fission energy accidents ranked first among energy sources in terms of their total economic cost, accounting for 41% of all property damage attributed to energy accidents. Another analysis found that coal, oil, liquid petroleum gas and hydroelectric accidents have resulted in greater economic impacts than nuclear power accidents. The Chernobyl accident in 1986 caused approximately 50 deaths from direct and indirect effects, and some temporary serious injuries from acute radiation syndrome. The future predicted mortality from increases in cancer rates is estimated at 4000 in the decades to come. Nuclear power works under an insurance framework that limits or structures accident liabilities in accordance with national and international conventions. It is often argued that this potential shortfall in liability represents an external cost not included in the cost of nuclear electricity. This cost is small, amounting to about 0.1% of the levelized cost of electricity, according to a study by the Congressional Budget Office in the United States. These beyond-regular insurance costs for worst-case scenarios are not unique to nuclear power. Hydroelectric power plants are similarly not fully insured against a catastrophic event such as dam failures. For example, the failure of the Banqiao Dam caused the death of an estimated 30,000 to 200,000 people, and 11 million people lost their homes. As private insurers base dam insurance premiums on limited scenarios, major disaster insurance in this sector is likewise provided by the state.
The Global Debate
The nuclear power debate concerns the controversy which has surrounded the deployment and use of nuclear fission reactors to generate electricity from nuclear fuel for civilian purposes. Proponents of nuclear energy regard it as a sustainable energy source that reduces carbon emissions and increases energy security by decreasing dependence on other sources that are often dependent on imports. For example, proponents note that annually, nuclear-generated electricity reduces 470 million metric tons of carbon dioxide emissions that would otherwise come from fossil fuels. Additionally, the amount of comparatively low waste that nuclear energy does create is safely disposed of by the large scale nuclear energy production facilities or it is repurposed and recycled for other energy uses. Proponents also claim that the present quantity of nuclear waste is small and can be reduced through the latest technology of newer reactors and that the operational safety record of fission-electricity in terms of deaths is so far unparalleled. Kharecha and Hansen estimated that global nuclear power has prevented an average of 1.84 million air pollution-related deaths and 64 gigatonnes of carbon dioxide-equivalent greenhouse gas emissions that would have resulted from fossil fuel burning. If continued, it could prevent up to 7 million deaths and 240 gigatonnes of emissions by 2050. Proponents also bring to attention the opportunity cost of using other forms of electricity. For example, the United States Environmental Protection Agency estimates that coal kills 30,000 people a year as a result of its environmental impact, while 60 people died in the Chernobyl disaster. A real world example of impact provided by proponents is the 650,000 ton increase in carbon emissions in the two months following the closure of the Vermont Yankee nuclear plant. A 2015 survey of AAAS members found that 65% support building more nuclear power plants, which rose to 79% among physicists. Opponents believe that nuclear power poses many threats to people's health and environment such as the risk of nuclear weapons proliferation, long-term safe waste management and terrorism in the future. They also contend that nuclear power plants are complex systems where many things can and have gone wrong. Critics find that one of the largest drawbacks to building new nuclear fission power plants are the high costs when compared to alternatives of sustainable energy sources. Proponents note that focusing on the levelized cost of energy, however, ignores the value premium associated with 24/7 dispatchable electricity and the cost of storage and backup systems necessary to integrate variable energy sources into a reliable electrical grid. Nuclear thus remains the dispatchable low-carbon technology with the lowest expected costs in 2025. Only large hydro reservoirs can provide a similar contribution at comparable costs but remain highly dependent on the natural endowments of individual countries. Overall, many opponents find that nuclear energy cannot meaningfully contribute to climate change mitigation. In general, they find it to be too dangerous, too expensive, to take too long for deployment, as much as to be an obstacle to achieving a transition towards sustainability and carbon-neutrality. These opponents find nuclear to be effectively a distraction in the competition for resources for the deployment and development of alternative, sustainable, energy system technologies. Nevertheless, there is ongoing research and debate over costs of new nuclear, especially in regions where seasonal energy storage is difficult to provide and which aim to phase out fossil fuels in favor of low carbon power faster than the global average. Some find that financial transition costs for a 100% renewables-based European energy system that has completely phased out nuclear energy could be more costly by 2050 based on current technologies when the grid only extends across Europe. Arguments of economics and safety are used by both sides of the debate. Nuclear power is comparable to, and in some cases lower, than many renewable energy sources in terms of lives lost per unit of electricity delivered. Nuclear reactors produce a much smaller volume of waste compared to renewable energy sources, although nuclear waste is much more toxic, expensive to manage and longer-lived compared to waste from renewable technologies. Nuclear waste can be dangerous if leaked to the environment, and need to be stored safely for thousands or even hundreds of thousand of years. Nuclear plants are also far more complex to decommission compared to renewable energy plants. A nuclear plant needs to be disassembled and removed and much of the disassembled nuclear plant needs to be stored as low-level nuclear waste for a few decades. Nuclear power may also pose the risk of nuclear proliferation. Separated plutonium and enriched uranium could be used for nuclear weapons, which pose a substantial global risk to human civilization and the environment. Analysis in 2015 by professor Barry W. Brook and colleagues found that nuclear energy could displace or remove fossil fuels from the electric grid completely within 10 years. This finding was based on the historically modest and proven rate at which nuclear energy was added in France and Sweden during their building programs in the 1980s. In a similar analysis, Brook had earlier determined that 50% of all global energy, including transportation synthetic fuels etc., could be generated within approximately 30 years if the global nuclear fission build rate was identical to historical proven installation rates calculated in gigawatts per year per unit of global GDP. This is in contrast to the conceptual studies for 100% renewable energy systems, which would require an order of magnitude more costly global investment per year, which has no historical precedent. These renewable scenarios would also need far greater land devoted to onshore wind and onshore solar projects. Brook notes that the principal limitations on nuclear fission are not technical, economic or fuel-related, but are instead linked to complex issues of societal acceptance, fiscal and political inertia, and inadequate critical evaluation of the real-world constraints facing the other low-carbon alternatives. The median land area used by US nuclear power stations per 1 gigawatt installed capacity is 1 square kilometer. To generate the same amount of electricity annually from solar PV would require about 75 square kilometers, and from a wind farm about 36 square kilometers. Not included in this, is land required for the associated transmission lines, water supply, rail lines, mining and processing of nuclear fuel, and for waste.