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 the capital city of Harrisburg, Pennsylvania. 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 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.
The RBMK is a class of graphite-moderated nuclear power reactor designed and built by the Soviet Union. The name refers to its design where, instead of a large steel pressure vessel surrounding the entire core, the core is surrounded by a cylindrical annular steel tank inside a concrete vault and each fuel assembly is enclosed in an individual 8 cm (inner) diameter pipe. The channels also contain the coolant, and are surrounded by graphite.
Davis–Besse Nuclear Power Station is a 894 megawatt (MW) nuclear power plant, located northeast of Oak Harbor, Ohio in Ottawa County, Ohio. It has a single pressurized water reactor. Davis–Besse is operated by Energy Harbor.
Passive nuclear safety is a design approach for safety features, implemented in a nuclear reactor, that does not require any active intervention on the part of the operator or electrical/electronic feedback in order to bring the reactor to a safe shutdown state, in the event of a particular type of emergency. Such design features tend to rely on the engineering of components such that their predicted behaviour would slow down, rather than accelerate the deterioration of the reactor state; they typically take advantage of natural forces or phenomena such as gravity, buoyancy, pressure differences, conduction or natural heat convection to accomplish safety functions without requiring an active power source. Many older common reactor designs use passive safety systems to a limited extent, rather, relying on active safety systems such as diesel-powered motors. Some newer reactor designs feature more passive systems; the motivation being that they are highly reliable and reduce the cost associated with the installation and maintenance of systems that would otherwise require multiple trains of equipment and redundant safety class power supplies in order to achieve the same level of reliability. However, weak driving forces that power many passive safety features can pose significant challenges to effectiveness of a passive system, particularly in the short term following an accident.
The Chernobyl Nuclear Power Plant is a nuclear power plant undergoing decommissioning. ChNPP is located near the abandoned city of Pripyat in northern Ukraine, 16.5 kilometers (10 mi) northwest of the city of Chernobyl, 16 kilometers (10 mi) from the Belarus–Ukraine border, and about 100 kilometers (62 mi) north of Kyiv. The plant was cooled by an engineered pond, fed by the Pripyat River about 5 kilometers (3 mi) northwest from its juncture with the Dnieper.
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.
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 Saxton Nuclear Experiment Station, also known as the Saxton Nuclear Generating Station or Saxton Nuclear Experimental Corporation Facility, was a small nuclear power plant located in Bedford County, near Saxton, Pennsylvania.
The advanced heavy-water reactor (AHWR) or AHWR-300 is the latest Indian design for a next-generation nuclear reactor that burns thorium in its fuel core. It is slated to form the third stage in India's three-stage fuel-cycle plan. This phase of the fuel cycle plan was supposed to be built starting with a 300 MWe prototype in 2016.
The BN-600 reactor is a sodium-cooled fast breeder reactor, built at the Beloyarsk Nuclear Power Station, in Zarechny, Sverdlovsk Oblast, Russia. It has a 600 MWe gross capacity and a 560 MWe net capacity, provided to the Middle Urals power grid. It has been in operation since 1980 and represents an improvement to the preceding BN-350 reactor. In 2014, its larger sister reactor, the BN-800 reactor, began operation.
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 9.1 earthquake and tsunami that hit Japan on March 11, 2011. The chain of events caused radiation leaks and permanently damaged several of its reactors, making them impossible to restart. The working reactors were not restarted after the events.
The Tōkai Nuclear Power Plant was Japan's first commercial nuclear power plant. The first unit was built in the early 1960s to the British Magnox design, and generated power from 1966 until it was decommissioned in 1998. A second unit, built at the site in the 1970s, was the first in Japan to produce over 1000 MW of electricity. The site is located in Tokai in the Naka District in Ibaraki Prefecture, Japan and is operated by the Japan Atomic Power Company. The total site area amounts to 0.76 km2 with 0.33 km2, or 43% of it, being green area that the company is working to preserve.
The three primary objectives of nuclear reactor safety systems as defined by the U.S. Nuclear Regulatory Commission are to shut down the reactor, maintain it in a shutdown condition and prevent the release of radioactive material.
The United States Government Accountability Office reported more than 150 incidents from 2001 to 2006 of nuclear plants not performing within acceptable safety guidelines. According to a 2010 survey of energy accidents, there have been at least 56 accidents at nuclear reactors in the United States. The most serious of these was the Three Mile Island accident in 1979. Davis-Besse Nuclear Power Plant has been the source of two of the top five most dangerous nuclear incidents in the United States since 1979. Relatively few accidents have involved fatalities.
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.
Fukushima Daiichi is a multi-reactor nuclear power site in the Fukushima Prefecture of Japan. A nuclear disaster occurred there after a 9.0 magnitude earthquake and subsequent tsunami on 11 March 2011. The earthquake triggered a scram shut down of the three active reactors, and the ensuing tsunami crippled the site, stopped the backup diesel generators, and caused a station blackout. The subsequent lack of cooling led to explosions and meltdowns, with problems at three of the six reactors and in one of the six spent-fuel pools.
The Fukushima Daiichi reactor, was 1 out of 4 reactors seriously affected during the Fukushima Daiichi nuclear disaster on 11 March 2011. Overall, the plant had 6 separate boiling water reactors originally designed by General Electric (GE), and maintained by the Tokyo Electric Power Company (TEPCO). At the time of the earthquake, Reactor 4 had been de-fueled while 5 and 6 were in cold shutdown for planned maintenance.
The Fukushima Daiichi reactor, was 1 out of 4 reactors seriously affected during the Fukushima Daiichi nuclear disaster on 11 March 2011. Overall, the plant had 6 separate boiling water reactors originally designed by General Electric (GE), and maintained by the Tokyo Electric Power Company (TEPCO). At the time of the earthquake, Reactor 4 had been de-fueled while 5 and 6 were in cold shutdown for planned maintenance. Unit 1 was immediately shut down automatically after the earthquake, and emergency generators came online to control electronics and coolant systems. However, the tsunami following the earthquake quickly flooded the low-lying rooms in which the emergency generators were housed. The flooded generators failed, cutting power to the critical pumps that must continuously circulate coolant water through the reactor core. While the government tried pumping fresh water into the core, it was already too late due to overheat. In the hours and days that followed, Unit 1 experienced a full meltdown.
The Fukushima Daiichi reactor, was 1 out of 4 reactors seriously affected during the Fukushima Daiichi nuclear disaster on 11 March 2011. Overall, the plant had 6 separate boiling water reactors originally designed by General Electric (GE), and maintained by the Tokyo Electric Power Company (TEPCO). In the aftermath, Unit 3 experienced hydrogen gas explosions and suffered a partial meltdown, along with the other two reactors in operation at the time the tsunami struck. Reactor 4 had been de-fueled while 5 and 6 were in cold shutdown for planned maintenance.
