A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. When a fissile nucleus like uranium-235 or plutonium-239 absorbs a neutron, it splits into lighter nuclei, releasing energy, gamma radiation, and free neutrons, which can induce further fission in a self-sustaining chain reaction. The process is carefully controlled using control rods and neutron moderators to regulate the number of neutrons that continue the reaction, ensuring the reactor operates safely, although inherent control by means of delayed neutrons also plays an important role in reactor output control. The efficiency of energy conversion in nuclear reactors is significantly higher compared to conventional fossil fuel plants; a kilo of uranium-235, if all the atoms were split, would release about three million times more energy than a kilo of coal.
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 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. It is somewhat like a boiling water reactor as water boils in the pressure tubes. It is one of two power reactor types to enter serial production in the Soviet Union during the 1970s, the other being the VVER reactor. 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.
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, or a 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.
The International Nuclear and Radiological Event Scale (INES) was introduced in 1990 by the International Atomic Energy Agency (IAEA) in order to enable prompt communication of safety significant information in case of nuclear accidents.
The Chernobyl Nuclear Power Plant (ChNPP) 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 River.
The Chernobyl disaster began on 26 April 1986 with the explosion of the No. 4 reactor of the Chernobyl Nuclear Power Plant near the city of Pripyat in northern Ukraine, near the Belarus border in the Soviet Union. It is one of only two nuclear energy accidents rated at the maximum severity on the International Nuclear Event Scale, the other being the 2011 Fukushima nuclear accident. The response involved more than 500,000 personnel and cost an estimated 18 billion rubles. It remains the worst nuclear disaster in history, and the costliest disaster in human history, with an estimated cost of $700 billion USD.
The water-water energetic reactor (WWER), or VVER is a series of pressurized water reactor designs originally developed in the Soviet Union, and now Russia, by OKB Gidropress. The idea of such a reactor was proposed at the Kurchatov Institute by Savely Moiseevich Feinberg. VVER were originally developed before the 1970s, and have been continually updated. They were one of the initial reactors developed by the USSR, the other being the infamous RBMK. As a result, the name VVER is associated with a wide variety of reactor designs spanning from generation I reactors to modern generation III+ reactor designs. Power output ranges from 70 to 1300 MWe, with designs of up to 1700 MWe in development. The first prototype VVER-210 was built at the Novovoronezh Nuclear Power Plant.
Russia is one of the world's largest producers of nuclear energy. In 2020 total electricity generated in nuclear power plants in Russia was 215.746 TWh, 20.28% of all power generation. The installed gross capacity of Russian nuclear reactors is 29.4 GW in December 2020.
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".
Leningrad Nuclear Power Plant ) is a nuclear power plant located in the town of Sosnovy Bor in Russia's Leningrad Oblast, on the southern shore of the Gulf of Finland, some 70 kilometres (43 mi) to the west of the city centre of Saint Petersburg.
The Kursk Nuclear Power Plant is one of the three biggest nuclear power plants (NPPs) in Russia and one of the four biggest electricity producers in the country. It is located on the bank of the Seym River about 40 kilometers west of the city of Kursk, midway between it and the town of Lgov, in western Russia. The nearby city of Kurchatov was founded when construction of the plant began. The plant feeds the grid for Kursk Oblast and 19 other regions. As of 2024, the site houses two active reactors and two decommissioned older units. It also houses the partially built Kursk 5 and Kursk 6 units which had construction halted, and two new VVER designs are under construction.
Obninsk Nuclear Power Plant was built in the "Science City" of Obninsk, Kaluga Oblast, about 110 km (68 mi) southwest of Moscow, Soviet Union. Connected to the power grid in June 1954, Obninsk was the first grid-connected nuclear power plant in the world, i.e. the first nuclear reactor that produced electricity industrially, albeit at small scale. It was located at the Institute of Physics and Power Engineering. The plant is also known as APS-1 Obninsk. It remained in operation between 1954 and 2002. Its production of electricity for the grid ceased in 2002; thereafter it functioned as a research and isotope production plant only.
Ukraine operates four nuclear power plants with 15 reactors located in Volhynia and South Ukraine. The total installed nuclear power capacity is over 13 GWe, ranking 7th in the world in 2020. Energoatom, a Ukrainian state enterprise, operates all four active nuclear power stations in Ukraine. In 2019, nuclear power supplied over 20% of Ukraine's energy.
The anti-nuclear movement in Russia is a social movement against nuclear technologies, largely stemming from the results of the Chernobyl incident in 1986. During the most active phase of the anti-nuclear movement, from 1988 to 1992, construction of over 100 nuclear projects were prevented on the territory of the Soviet Union. Also, the economic troubles of the 1990s led to a reduction in the number of construction projects. This deprived the anti-nuclear movement of its raison d’être. At the same time, it too was affected by financial difficulties, in particular the lack of donations, which continues to be an issue today. Since the 2000s the Russian Government embarked on highly pro-nuclear policy, with plans to invest billions of dollars in developing the nuclear industry, which leaves the movement with big challenges.
This is a history of nuclear power as realized through the first artificial fission of atoms that would lead to the Manhattan Project and, eventually, to using nuclear fission to generate electricity.
The Fukushima Daiichi nuclear disaster genshiryoku hatsudensho jiko) 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.
Viktor Petrovich Bryukhanov was the manager of construction of the Chernobyl Nuclear Power Plant and the director of the plant from 1970 to 1986.
The Chernobyl disaster was a catastrophic nuclear disaster that occurred in the early hours of 26 April 1986, at the Chernobyl Nuclear Power Plant in Soviet Ukraine. The accident occurred when Reactor Number 4 exploded and destroyed most of the reactor building, spreading debris and radioactive material across the surrounding area, and over the following days and weeks, most of mainland Europe was contaminated with radionuclides that emitted dangerous amounts of ionizing radiation. To investigate the causes of the accident, the International Atomic Energy Agency (IAEA) used its organization, the International Nuclear Safety Advisory Group (INSAG).
