The Three Mile Island accident was a partial nuclear meltdown of the Unit 2 reactor (TMI-2) of the Three Mile Island Nuclear Generating Station on the Susquehanna River in Londonderry Township, near Harrisburg, the capital city of Pennsylvania, United States. The reactor accident began at 4:00 a.m. on March 28, 1979, and released radioactive gases and radioactive iodine into the environment. It is the worst accident in U.S. commercial nuclear power plant history. On the seven-point logarithmic International Nuclear Event Scale, the TMI-2 reactor accident is rated Level 5, an "Accident with Wider Consequences".
A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants. In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated, high pressure water then flows to a steam generator, where it transfers its thermal energy to lower pressure water of a secondary system where steam is generated. The steam then drives turbines, which spin an electric generator. In contrast to a boiling water reactor (BWR), pressure in the primary coolant loop prevents the water from boiling within the reactor. All light-water reactors use ordinary water as both coolant and neutron moderator. Most use anywhere from two to four vertically mounted steam generators; VVER reactors use horizontal steam generators.
A boiling water reactor (BWR) is a type of light water nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor (PWR), which is also a type of light water nuclear reactor.
The United States Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operations on January 19, 1975, as one of two successor agencies to the United States Atomic Energy Commission. Its functions include overseeing reactor safety and security, administering reactor licensing and renewal, licensing radioactive materials, radionuclide safety, and managing the storage, security, recycling, and disposal of spent fuel.
Hope Creek Nuclear Generating Station is a thermal nuclear power plant located in Lower Alloways Creek Township, in Salem County, New Jersey, United States, on the same site on Artificial Island as the two-unit Salem Nuclear Power Plant. The plant is owned and operated by PSEG Nuclear LLC. It has one unit, a boiling water reactor (BWR) manufactured by GE. The complex was designed for two units, but the second unit was cancelled in 1981. It has a generating capacity of 1,268 MWe. The plant came online on July 25, 1986, licensed to operate until 2026. In 2009, PSEG applied for a 20-year license renewal, which it received in 2011 to operate until 2046. With its combined output of 3,572 megawatts, the Salem-Hope Creek complex is the largest nuclear generating facility in the Eastern United States and the second largest nationwide, after the Palo Verde Nuclear Generating Station in Arizona.
Surry Power Station is a nuclear power plant located in Surry County in southeastern Virginia, in the South Atlantic United States. The power station lies on an 840-acre (340 ha) site adjacent to the James River across from Jamestown, slightly upriver from Smithfield and Newport News. Surry is operated by Dominion Generation and owned by Dominion Resources, Inc.
Probabilistic risk assessment (PRA) is a systematic and comprehensive methodology to evaluate risks associated with a complex engineered technological entity or the effects of stressors on the environment.
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 advanced boiling water reactor (ABWR) is a Generation III boiling water reactor. The ABWR is currently offered by GE Hitachi Nuclear Energy (GEH) and Toshiba. The ABWR generates electrical power by using steam to power a turbine connected to a generator; the steam is boiled from water using heat generated by fission reactions within nuclear fuel. Kashiwazaki-Kariwa unit 6 is considered the first Generation III reactor in the world.
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 $15 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 the consequences of radioactive release.
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", estimated maximum possible damage from a meltdown with no containment building at a large nuclear reactor.
The Economic Simplified Boiling Water Reactor (ESBWR) is a passively safe generation III+ reactor design derived from its predecessor, the Simplified Boiling Water Reactor (SBWR) and from the Advanced Boiling Water Reactor (ABWR). All are designs by GE Hitachi Nuclear Energy (GEH), and are based on previous Boiling Water Reactor designs.
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.
Core damage frequency (CDF) is a term used in probabilistic risk assessment (PRA) that indicates the likelihood of an accident that would cause severe damage to a nuclear fuel in a nuclear reactor core. Core damage accidents are considered extremely serious because severe damage to the fuel in the core prevents adequate heat removal or even safe shutdown, which can lead to a nuclear meltdown. Some sources on CDF consider core damage and core meltdown to be the same thing, and different methods of measurement are used between industries and nations, so the primary value of the CDF number is in managing the risk of core accidents within a system and not necessarily to provide large-scale statistics.
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.
Boiling water reactor safety systems are nuclear safety systems constructed within boiling water reactors in order to prevent or mitigate environmental and health hazards in the event of accident or natural disaster.
General Electric's BWR product line of boiling water reactors represents the designs of a relatively large (~18%) percentage of the commercial fission reactors around the world.
