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 nuclear fuel is much higher than fossil fuels; the 5% enriched uranium used in the newest reactors has an energy density 120,000 times higher than coal.
A nuclear power plant (NPP), also known as a nuclear power station (NPS), nuclear generating station (NGS) or atomic power station (APS) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces electricity. As of September 2023, the International Atomic Energy Agency reported that there were 410 nuclear power reactors in operation in 32 countries around the world, and 57 nuclear power reactors under construction.
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.
Dry cask storage is a method of storing high-level radioactive waste, such as spent nuclear fuel that has already been cooled in a spent fuel pool for at least one year and often as much as ten years. Casks are typically steel cylinders that are either welded or bolted closed. The fuel rods inside are surrounded by inert gas. Ideally, the steel cylinder provides leak-tight containment of the spent fuel. Each cylinder is surrounded by additional steel, concrete, or other material to provide radiation shielding to workers and members of the public.
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 kilometres (10 mi) northwest of the city of Chernobyl, 16 kilometres (10 mi) from the Belarus–Ukraine border, and about 100 kilometres (62 mi) north of Kyiv. The plant was cooled by an engineered pond, fed by the Pripyat River about 5 kilometres (3 mi) northwest from its juncture with the Dnieper River.
The Ignalina Nuclear Power Plant is a decommissioned two-unit RBMK-1500 nuclear power station in Visaginas Municipality, Lithuania. It was named after the nearby city of Ignalina. Due to the plant's similarities to the infamous Chernobyl Nuclear Power Plant in both reactor design and lack of a robust containment building, Lithuania agreed to close the plant as part of its agreement of accession to the European Union. Unit 1 was closed in December 2004; Unit 2 in December 2009. The plant accounted for 25% of Lithuania's electricity generating capacity and supplied about 70% of Lithuania's electrical demand. It was closed on December 31, 2009. Proposals have been made to construct a new nuclear power plant at the site, but such plans have yet to come to fruition.
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 THTR-300 was a thorium cycle high-temperature nuclear reactor rated at 300 MW electric (THTR-300) in Hamm-Uentrop, Germany. It started operating in 1983, synchronized with the grid in 1985, operated at full power in February 1987 and was shut down September 1, 1989. The THTR-300 served as a prototype high-temperature reactor (HTR) to use the TRISO pebble fuel produced by the AVR, an experimental pebble bed operated by VEW. The THTR-300 cost €2.05 billion and was predicted to cost an additional €425 million through December 2009 in decommissioning and other associated costs. The German state of North Rhine Westphalia, Federal Republic of Germany, and Hochtemperatur-Kernkraftwerk GmbH (HKG) financed the THTR-300’s construction.
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.
The New Safe Confinement is a structure put in place in 2016 to confine the remains of the number 4 reactor unit at the Chernobyl Nuclear Power Plant, in Ukraine, which was destroyed during the Chernobyl disaster in 1986. The structure also encloses the temporary Shelter Structure (sarcophagus) that was built around the reactor immediately after the disaster. The New Safe Confinement is designed to prevent the release of radioactive contaminants, protect the reactor from external influence, facilitate the disassembly and decommissioning of the reactor, and prevent water intrusion.
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.
A graphite-moderated reactor is a nuclear reactor that uses carbon as a neutron moderator, which allows natural uranium to be used as nuclear fuel.
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 Fukushima Daiichi Nuclear Power Plant is a disabled nuclear power plant located on a 350-hectare (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 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.
Nuclear power has various environmental impacts, both positive and negative, including the construction and operation of the plant, the nuclear fuel cycle, and the effects of nuclear accidents. Nuclear power plants do not burn fossil fuels and so do not directly emit carbon dioxide. The carbon dioxide emitted during mining, enrichment, fabrication and transport of fuel is small when compared with the carbon dioxide emitted by fossil fuels of similar energy yield, however, these plants still produce other environmentally damaging wastes. Nuclear energy and renewable energy have reduced environmental costs by decreasing CO2 emissions resulting from energy consumption.
Smolensk Nuclear Power Plant is a nuclear power station in Russia. It is located in the Smolensk region, in Desnogorsk province, approximately 100 kilometres (62 mi) from Smolensk, 115 kilometres (71 mi) from Bryansk and 320 kilometres (200 mi) from Moscow. Smolensk Nuclear Power Plant is the biggest power generating station in the north-western region of the united energy system of the Russian Federation. Smolensk NPP has an outer appearance similar to that of Chernobyl NPP units 3-4, as both are later generation RBMKs.
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 BN-800 reactor is a sodium-cooled fast breeder reactor, built at the Beloyarsk Nuclear Power Station, in Zarechny, Sverdlovsk Oblast, Russia. The reactor is designed to generate 880 MW of electrical power. The plant was considered part of the weapons-grade Plutonium Management and Disposition Agreement signed between the United States and Russia. The reactor is part of the final step for a plutonium-burner core The plant reached its full power production in August 2016. According to Russian business journal Kommersant, the BN-800 project cost 140.6 billion rubles.
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).
