WASH-740 was a report published by the U.S. Atomic Energy Commission (USAEC) in 1957. This report, called "Theoretical Possibilities and Consequences of Major Accidents in Large Nuclear Power Plants" (also known as "The Brookhaven Report"), estimated maximum possible damage from a meltdown with no containment building at a large nuclear reactor.
The conclusions of this study estimated the possible effects of a "maximum credible accident" for nuclear reactors then envisioned as being 3400 deaths, 43,000 injuries and property damage of $7 billion ($57bn adjusted for inflation in 2012 since 1957). The estimate of probability was one in a hundred thousand to one in a billion per reactor-year. When WASH-740 was revised in 1964-65 to account for the larger reactors then being designed, the new figures indicated that there could be as many as 45,000 deaths, 100,000 injuries, and $17 billion in property damage ($125bn adjusted for inflation since 1964).
However, the assumptions underlying the results were unrealistic (including the worst meteorological conditions, no containment building, and that half the reactor core is released into the atmosphere as micrometre-sized pellets without any examination of how this might occur). These were due to conservatism (estimating the maximum possible damage) and the need to use atomic bomb fallout data, which had been collected from tests (computers in 1955 being greatly insufficient to do the calculations).
As knowledge, models and computers improved the conclusions of this report were replaced by those of first WASH-1400 (1975, The Rasmussen Report), then CRAC-II (1982), and most recently NUREG-1150 (1991). Now all of these studies are considered obsolete (see the disclaimer to NUREG-1150), and are being replaced by the State-of-the-Art Reactor Consequence Analyses (SOARCA) study.
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The Three Mile Island accident was a partial meltdown of the Three Mile Island, Unit 2 (TMI-2) reactor in Pennsylvania, United States. It began at 4 a.m. on March 28, 1979. It is the most significant accident in U.S. commercial nuclear power plant history. On the seven-point International Nuclear Event Scale, it is rated Level 5 – Accident with Wider Consequences.
A nuclear meltdown is a severe nuclear reactor accident that results in core damage from overheating. The term nuclear meltdown is not officially defined by the International Atomic Energy Agency or by the United States Nuclear Regulatory Commission. It has been defined to mean the accidental melting of the core of a nuclear reactor, however, and is in common usage a reference to the core's either complete or partial collapse.
A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility. Examples include lethal effects to individuals, large radioactivity release to the environment, reactor core melt." The prime example of a "major nuclear accident" is one in which a reactor core is damaged and significant amounts of radioactive isotopes are released, such as in the Chernobyl disaster in 1986 and Fukushima nuclear disaster in 2011.
Tokyo Electric Power Company Holdings, Incorporated, also known as Toden or TEPCO, is a Japanese electric utility holding company servicing Japan's Kantō region, Yamanashi Prefecture, and the eastern portion of Shizuoka Prefecture. This area includes Tokyo. Its headquarters are located in Uchisaiwaicho, Chiyoda, Tokyo, and international branch offices exist in Washington, D.C., and London. It is a founding member of strategic consortiums related to energy innovation and research; such as JINED, INCJ and MAI.
The Windscale fire of 10 October 1957 was the worst nuclear accident in the United Kingdom's history, and one of the worst in the world, ranked in severity at level 5 out of a possible 7 on the International Nuclear Event Scale. The fire was in Unit 1 of the two-pile Windscale site on the north-west coast of England in Cumberland. The two graphite-moderated reactors, referred to at the time as "piles," had been built as part of the British post-war atomic bomb project. Windscale Pile No. 1 was operational in October 1950, followed by Pile No. 2 in June 1951.
A containment building is a reinforced steel, concrete or lead structure enclosing a nuclear reactor. It is designed, in any emergency, to contain the escape of radioactive steam or gas to a maximum pressure in the range of 275 to 550 kPa. The containment is the fourth and final barrier to radioactive release, the first being the fuel ceramic itself, the second being the metal fuel cladding tubes, the third being the reactor vessel and coolant system.
WASH-1400, 'The Reactor Safety Study', was a report produced in 1975 for the Nuclear Regulatory Commission by a committee of specialists under Professor Norman Rasmussen. It "generated a storm of criticism in the years following its release". In the years immediately after its release, WASH-1400 was followed by a number of reports that either peer reviewed its methodology or offered their own judgments about probabilities and consequences of various events at commercial reactors. In at least a few instances, some offered critiques of the study's assumptions, methodology, calculations, peer review procedures, and objectivity. A succession of reports, including NUREG-1150, the State-of-the-Art Reactor Consequence Analyses and others, have carried-on the tradition of PRA and its application to commercial power plants.
The Price-Anderson Nuclear Industries Indemnity Act is a United States federal law, first passed in 1957 and since renewed several times, which governs liability-related issues for all non-military nuclear facilities constructed in the United States before 2026. The main purpose of the Act is to partially compensate the nuclear industry against liability claims arising from nuclear incidents while still ensuring compensation coverage for the general public. The Act establishes a no fault insurance-type system in which the first approximately $15 billion is industry-funded as described in the Act. Any claims above the $12.6 billion would be covered by a Congressional mandate to retroactively increase nuclear utility liability or would be covered by the federal government. At the time of the Act's passing, it was considered necessary as an incentive for the private production of nuclear power — this was because electric utilities viewed the available liability coverage as inadequate.
The AP1000 is a nuclear power plant designed and sold by Westinghouse Electric Company. The plant is a pressurized water reactor with improved use of passive nuclear safety and many design features intended to lower its capital cost and improve its economics.
CRAC-II is both a computer code and the 1982 report of the simulation results performed by Sandia National Laboratories for the Nuclear Regulatory Commission. The report is sometimes referred to as the CRAC-II report because it is the computer program used in the calculations, but the report is also known as the 1982 Sandia Siting Study or as NUREG/CR-2239. The computer program MACCS2 has since replaced CRAC-II for consequences of radioactive release.
NUREG-1150 "Severe Accident Risks: An Assessment for Five U.S. Nuclear Power Plants", published December 1990 by the Nuclear Regulatory Commission (NRC) is a follow-up to the WASH-1400 and CRAC-II safety studies that employs the methodology of plant-specific Probabilistic Risk Assessment (PRA). The research team, led by Denwood Ross, Joseph Murphy, and Mark Cunningham, concluded that the current generation of nuclear power plants exceeded NRC safety goals.
Nuclear safety is defined by the International Atomic Energy Agency (IAEA) as "The achievement of proper operating conditions, prevention of accidents or mitigation of accident consequences, resulting in protection of workers, the public and the environment from undue radiation hazards". The IAEA defines nuclear security as "The prevention and detection of and response to, theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving nuclear materials, other radioactive substances or their associated facilities".
Nuclear safety in the United States is governed by federal regulations issued by the Nuclear Regulatory Commission (NRC). The NRC regulates all nuclear plants and materials in the United States except for nuclear plants and materials controlled by the U.S. government, as well those powering naval vessels.
The Fukushima Daiichi Nuclear Power Plant is a disabled nuclear power plant located on a 3.5-square-kilometre (860-acre) site in the towns of Ōkuma and Futaba in Fukushima Prefecture, Japan. The plant suffered major damage from the magnitude 9.0 earthquake and tsunami that hit Japan on March 11, 2011. The chain of events caused radiation leaks and permanently damaged several of its American-designed reactors, making them impossible to restart. By political decision, the remaining reactors were not restarted.
The State-of-the-Art Reactor Consequence Analyses (SOARCA) is a study of nuclear power plant safety conducted by the Nuclear Regulatory Commission. The purpose of the SOARCA is assessment of possible impact on population caused by major radiation accidents that might occur at NPPs. This new study updates older studies with the latest state-of-the-art computer models and incorporates new plant safety and security enhancements.
The Sodium Reactor Experiment was a pioneering nuclear power plant built by Atomics International at the Santa Susana Field Laboratory near Simi Valley, California. The reactor operated from 1957 to 1964. On December 20, 1951, the first Experimental Breeder Reactor in Idaho (EBR-I) was the first reactor to produce electricity. On July 17, 1955, the BORAX-III reactor, also in Idaho, was briefly connected to the local power grid, and went on to provide all the electric power for the nearby city of Arco and several facilities of the National Reactor Testing Station. On July 12, 1957 the Sodium Reactor Experiment became the first nuclear reactor in California to produce electrical power for a commercial power grid by powering the nearby city of Moorpark. In July 1959, the reactor experienced a partial meltdown when 13 of the reactor's 43 fuel elements partially melted, and a controlled release of radioactive gas into the atmosphere occurred. The reactor was repaired and restarted in September 1960. In February 1964, the Sodium Reactor Experiment was in operation for the last time. Removal of the deactivated reactor was completed in 1981. Technical analyses of the 1959 incident have produced contrasting conclusions regarding the types and quantities of radioactive materials released. Members of the neighboring communities have expressed concerns about the possible impacts on their health and environment from the incident. In August 2009, 50 years after the occurrence, the Department of Energy hosted a community workshop to discuss the 1959 incident.
The Fukushima nuclear disaster was a 2011 nuclear accident at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan. The proximate cause of the nuclear disaster was the 2011 Tōhoku earthquake and tsunami natural disaster that occurred on 11 March 2011 and was the most powerful earthquake ever recorded in Japan. The earthquake triggered a powerful tsunami, with 13–14 meter high waves causing damage to the nuclear power plant. The result is the most severe nuclear accident since the Chernobyl disaster in 1986, classified as level seven on the International Nuclear Event Scale (INES), after initially being classified as level five, joining Chernobyl as the only other accident to receive such classification. While the 1957 explosion at the Mayak facility was the second worst by radioactivity released, the INES ranks incidents by impact on population, so Chernobyl and Fukushima rank higher than the 10,000 evacuated from the classified restricted Mayak site in rural southern Urals.
The Fukushima disaster cleanup is an ongoing attempt to limit radioactive contamination from the three nuclear reactors involved in the Fukushima Daiichi nuclear disaster that followed the earthquake and tsunami on 11 March 2011. The affected reactors were adjacent to one another and accident management was made much more difficult because of the number of simultaneous hazards concentrated in a small area. Failure of emergency power following the tsunami resulted in loss of coolant from each reactor, hydrogen explosions damaging the reactor buildings, and water draining from open-air spent fuel pools. Plant workers were put in the position of trying to cope simultaneously with core meltdowns at three reactors and exposed fuel pools at three units.
A Filtered Containment Venting System (FCVS) is an accident management system designed to minimize the release of fission products when releasing the pressure of the containment building in the case of a severe nuclear accident. As a Severe Accident Management Measure (SAMM), containment venting cannot prevent a meltdown but can help alleviate its consequences on the environment.
The Fukushima Daiichi nuclear disaster was a series of equipment failures, nuclear meltdowns, and releases of radioactive materials at the Fukushima I Nuclear Power Plant, following the Tōhoku earthquake and tsunami on 11 March 2011. It is the largest nuclear disaster since the Chernobyl disaster of 1986.