Chernobyl Nuclear Power Plant
Encyclopedia
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
power station
Power station
A power station is an industrial facility for the generation of electric energy....
near the city of Pripyat, Ukraine, 18 km (11.2 mi) northwest of the city of Chernobyl, 16 km (9.9 mi) from the Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...
–Belarus
Belarus
Belarus , officially the Republic of Belarus, is a landlocked country in Eastern Europe, bordered clockwise by Russia to the northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Its capital is Minsk; other major cities include Brest, Grodno , Gomel ,...
border, and about 110 km (68.4 mi) north of Kiev
Kiev
Kiev or Kyiv is the capital and the largest city of Ukraine, located in the north central part of the country on the Dnieper River. The population as of the 2001 census was 2,611,300. However, higher numbers have been cited in the press....
. Reactor 4 was the site of the Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
in 1986.
The nuclear power plant site is to be cleared by 2065. On January 3, 2010, a Ukrainian law stipulating a "programme" toward this objective came into effect.
Construction
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
times, consisted of four reactors of type RBMK-1000
RBMK
RBMK is an initialism for the Russian reaktor bolshoy moshchnosti kanalniy which means "High Power Channel-type Reactor", and describes a class of graphite-moderated nuclear power reactor which was built in the Soviet Union. The RBMK reactor was the type involved in the Chernobyl disaster...
, each capable of producing 1,000 megawatt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s (MW) of electric power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
(3.2 GW of thermal power), and the four together produced about 10% of Ukraine's electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
at the time of the accident. The Chernobyl station is 18 km (11.2 mi) northwest of the city of Chernobyl, 16 km (9.9 mi) from the border of Ukraine and Belarus and about 100 km (62.1 mi) north of Kiev
Kiev
Kiev or Kyiv is the capital and the largest city of Ukraine, located in the north central part of the country on the Dnieper River. The population as of the 2001 census was 2,611,300. However, higher numbers have been cited in the press....
. Construction of the plant and the nearby city of Pripyat
Prypiat, Ukraine
Pripyat is a ghost town near the Chernobyl Nuclear Power Plant in the Kiev Oblast of northern Ukraine, near the border with Belarus....
to house workers and their families began in 1970, with reactor No. 1 commissioned in 1977. It was the third nuclear power station in the Soviet Union of the RBMK-type (after Leningrad
Leningrad Nuclear Power Plant
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 to the west of the city centre of Saint Petersburg. It consists of four nuclear reactors of RBMK-1000 type. These reactors...
and Kursk
Kursk Nuclear Power Plant
The Nuclear power station Kursk is located in western Russia on the bank of the Seym River about 40 kilometers west of the city of Kursk. The nearby town of Kurchatov was founded when construction of the plant began...
), and the first ever nuclear power plant on Ukrainian soil. The completion of the first reactor in 1977 was followed by reactor No. 2 (1978), No. 3 (1981), and No. 4 (1983). Two more reactors, nos. 5 and 6, capable of producing 1,000 MW each, were under construction at the time of the accident. Reactor No. 5 was about 70% complete at the time of the accident
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
and was scheduled to start operating in 7 November 1986. However, the works were halted on January 1st 1988 leaving most of the machinery behind.
Units 3 and 4 were second generation units, where as units 1 and 2 were first-generation units (like those in operation at Kursk Nuclear Power Plant
Kursk Nuclear Power Plant
The Nuclear power station Kursk is located in western Russia on the bank of the Seym River about 40 kilometers west of the city of Kursk. The nearby town of Kurchatov was founded when construction of the plant began...
). Second-generation RBMK designs were fitted with a more secure accident localization system, as can be seen in pictures. It is fortunate that the accident happened in a second-generation unit; if it had happened in a first-generation unit, it could have been even more devastating. Today, many countries that were in the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
have been paid money from the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
to shut down such first-generation units, as they pose a threat to the environment.
Electrical systems
The power plant is connected to the 330 kV and 750 kV electrical grid. The block has two electrical generatorElectrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
s connected to the 750 kV grid by a single generator transformer. The generators are connected to their common transformer by two switches in series. Between them, the unit transformers are connected to supply power to the power plant's own systems; each generator can therefore be connected to the unit transformer to power the plant, or to the unit transformer and the generator transformer to also feed power to the grid. The 330 kV line is normally not used, and serves as an external power supply, connected by a station transformer to the power plant's electrical systems. The plant can be powered by its own generators, or get power from the 750 kV grid through the generator transformer, or from the 330 kV grid via the station transformer, or from the other power plant block via two reserve busbar
Busbar
In electrical power distribution, a bus bar is a strip of copper or aluminium that conducts electricity within a switchboard, distribution board, substation or other electrical apparatus....
s. In case of total external power loss, the essential systems can be powered by diesel generator
Diesel generator
A diesel generator is the combination of a diesel engine with an electrical generator to generate electrical energy....
s. Each unit transformer is connected to two 6 kV main power boards, A and B (e.g. 7A, 7B, 8A, 8B for generators 7 and 8), powering principal non-essential drivers and connected to transformers for the 4 kV main power and the 4 kV reserve busbar. The 7A, 7B, and 8B boards are also connected to the three essential power lines (namely for the coolant pumps), each also having its own diesel generator. In case of a coolant circuit failure with simultaneous loss of external power, the essential power can be supplied by the spinning down turbogenerators for about 45–50 seconds, during which time the diesel generators should start up. The generators are started automatically within 15 seconds at loss of off-site power.
Turbogenerators
The electrical energy is generated by a pair of 500 MW hydrogen-cooled turbogeneratorHydrogen-cooled turbogenerator
A hydrogen-cooled turbo generator is a turbo generator with gaseous hydrogen as a coolant. Hydrogen-cooled turbo generators are designed to provide a low-drag atmosphere and cooling for single-shaft and combined-cycle applications in combination with steam turbines...
s. These are located in the 600 m (1,969 ft)-long machine hall, adjacent to the reactor building. The turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
s—the venerable five-cylinder K-500-65/3000—are supplied by the Kharkiv
Kharkiv
Kharkiv or Kharkov is the second-largest city in Ukraine.The city was founded in 1654 and was a major centre of Ukrainian culture in the Russian Empire. Kharkiv became the first city in Ukraine where the Ukrainian Soviet Socialist Republic was proclaimed in December 1917 and Soviet government was...
turbine plant; the electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
s are the TBB-500. The turbine and the generator rotors are mounted on the same shaft; the combined weight of the rotor
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
s is almost 200 t (220.5 ST) and their nominal rotational speed is 3000 rpm. The turbogenerator is 39 m (128 ft) long and its total weight is 1200 t (1,322.8 ST). The coolant flow for each turbine is 82,880 t/h. The generator produces 20 kV 50 Hz AC power. The generator's stator is cooled by water while its rotor is cooled by hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
. The hydrogen for the generators is manufactured on-site by electrolysis
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
. The design and reliability of the turbines earned them the State Prize of Ukraine for 1979.
The Kharkiv turbine plant (now Turboatom) later developed a new version of the turbine, K-500-65/3000-2, in an attempt to reduce use of valuable metal. The Chernobyl plant was equipped with both types of turbines; Block 4 had the newer ones. The newer turbines, however, turned out to be more sensitive to their operating parameters, and their bearings
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
had frequent problems with vibration
Vibration
Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
s.
1982
In 1982, a partial core meltdownNuclear meltdown
Nuclear meltdown is an informal term for a severe nuclear reactor accident that results in core damage from overheating. The term is not officially defined by the International Atomic Energy Agency or by the U.S. Nuclear Regulatory Commission...
occurred in reactor No. 1 at the Chernobyl plant. The extent of the accident was not made public until years later, in 1985. The reactor was repaired and put back into operation within months.
1986
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
were affected by the accident. The radiation cloud spread as far away as Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, in Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
.
1991 fire
The Chernobyl Nuclear Plant utilized one large, open turbine hall for all four reactors without any separating walls. Each reactor had two turbines. On October 11, 1991, a fire broke out in the turbine hall of Reactor 2. The fire began in Reactor 2's Turbine 4 (ТГ-4 in Russian) due to a hydrogen leak, causing damage to the turbine and the turbine hall roof. The adjacent reactor hall and reactor were unaffected.After the 1991 fire, there was discussion about replacing the damaged Turbine 4 in Reactor 2 with Turbine 7 from Reactor 4 (the reactor damaged in 1986), because Turbine 7—undamaged in the 1986 explosion—was subsequently unused and was in working order, this would provide a low-cost alternative to full replacement of the turbine.
Ukraine's 1991 independence from the Soviet Union generated further discussion on the Chernobyl topic, because the Rada, Ukraine's new parliament, was composed largely of young reformers. Discussions about the future of nuclear energy in Ukraine helped move the government toward the political decision to cancel the operation of Reactor 2.
Decommissioning
After the explosion at reactor four, the remaining three reactors at the power plant continued to operate. In 1991, reactor two suffered a major fire, and was subsequently decommissioned. In November 1996, reactor one was shut down, followed by reactor three on December 15, 2000, making good on a promise by Ukrainian president Leonid KuchmaLeonid Kuchma
Leonid Danylovych Kuchma was the second President of independent Ukraine from 19 July 1994, to 23 January 2005. Kuchma took office after winning the 1994 presidential election against his rival, incumbent Leonid Kravchuk...
that the entire plant would be closed.
Even after the last reactor shutdown, people continue to work at the Chernobyl plant until reactor units 1, 2, and 3 are totally decommissioned, which is expected to take years. The first stage of decommissioning is the removal of the highly radioactive spent nuclear fuel
Spent nuclear fuel
Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor...
, which is placed in deep water cooling ponds. However, storage facilities for this are not suitable for long term containment, and those on site do not have the capacity for all the spent fuel from units 1, 2 and 3. A second facility is planned for construction that will use dry storage technology suitable for long term storage and have the required capacity.
Removal of uncontaminated equipment has begun at unit 1 and this work could be complete by 2020–2022.
The remains of reactor unit 4 will remain radioactive for some time. The isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
responsible for the majority of the external gamma radiation
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
dose at the site is Caesium-137
Caesium-137
Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
which has a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of about 30 years. It is likely that with no further decontamination work the gamma ray dosage at the site will return to background
Background radiation
Background radiation is the ionizing radiation constantly present in the natural environment of the Earth, which is emitted by natural and artificial sources.-Overview:Both Natural and human-made background radiation varies by location....
levels in about 300 years. However, as most of the alpha emitters
Alpha particle
Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, which is classically produced in the process of alpha decay, but may be produced also in other ways and given the same name...
are longer lived, the soil and many surfaces in and around the plant are likely to be contaminated with transuranic metals such as plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
and americium
Americium
Americium is a synthetic element that has the symbol Am and atomic number 95. This transuranic element of the actinide series is located in the periodic table below the lanthanide element europium, and thus by analogy was named after another continent, America.Americium was first produced in 1944...
, which have much longer half-lives. It is planned that the reactor buildings will be disassembled as soon as it is radiologically safe to do so.
Sarcophagus replacement
On September 17, 2007, it was announced that a new steel containment structure named the New Safe ConfinementNew Safe Confinement
The New Safe Confinement is the structure intended to contain the nuclear reactor at Chernobyl, Ukraine, part of which was destroyed by the Chernobyl disaster in 1986. The idea is to prevent the reactor wreck from leaking radioactive material into the environment...
(NSC) would be built to replace the aging and hastily-built sarcophagus that currently protects reactor unit 4. The project, financed by an international fund managed by the European Bank for Reconstruction and Development
European Bank for Reconstruction and Development
Founded in 1991, the European Bank for Reconstruction and Development uses the tools of investment to help build market economies and democracies in 30 countries from central Europe to central Asia. Its mission was to support the formerly communist countries in the process of establishing their...
(EBRD), will be designed and built by the French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
-led consortium Novarka, which includes the companies Bouygues
Bouygues
Bouygues S.A. is a French industrial group headquartered in the 8th arrondissement of Paris, France. Bouygues is listed on Euronext Paris exchange and is a blue chip in the CAC 40 stock market index. The company was founded in 1952 by Francis Bouygues and since 1989 has been led by his son Martin...
and Vinci. Novarka will build a giant arch-shaped structure out of steel, 190 m (623 ft) wide and 200 m (656 ft) long to cover the old crumbling concrete dome that is currently in use.
This steel casing project is expected to cost $1.4 billion (£700 million, €1 billion), and expected to be completed in 2013. A separate deal has also been made with the American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
firm Holtec to build a storage facility within the exclusion zone for nuclear waste produced by Chernobyl.
Tours to Chernobyl
The Emergency Situations Ministry of Ukraine will allow tourists to go on special tours of the plant in 2011.Other Chernobyl articles
- Chernobyl compared to other radioactivity releasesChernobyl compared to other radioactivity releasesThis article compares the radioactivity release and decay from the Chernobyl disaster with various other events which involved a release of uncontrolled radioactivity.-Chernobyl compared to background radiation:...
- Chernobyl disasterChernobyl disasterThe Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
- Chernobyl disaster effectsChernobyl disaster effectsThe Chernobyl disaster triggered the release of substantial amounts of radiation into the atmosphere in the form of both particulate and gaseous radioisotopes. It is the most significant unintentional release of radiation into the environment to date...
- Chernobyl HeartChernobyl HeartChernobyl Heart is a 2003 documentary film by Maryann DeLeo. The film won the Best Documentary Short Subject award at the 2004 Academy Awards....
- Cultural impact of the Chernobyl disaster
- List of Chernobyl-related articles
- List of Chernobyl-related charities
- Zone of alienationZone of alienationThe Chernobyl Nuclear Power Plant Zone, which is sometimes referred to as The Chernobyl Zone, The 30 Kilometer Zone, The Zone of Alienation, or simply The Zone The Chernobyl Nuclear Power Plant Zone, which is sometimes referred to as The Chernobyl Zone, The 30 Kilometer Zone, The Zone of...
Other accidents
- List of civilian nuclear accidents
- List of military nuclear accidents
- Three Mile Island accidentThree Mile Island accidentThe Three Mile Island accident was a core meltdown in Unit 2 of the Three Mile Island Nuclear Generating Station in Dauphin County, Pennsylvania near Harrisburg, United States in 1979....
Nuclear safety
- International Nuclear Event ScaleInternational Nuclear Event ScaleThe International Nuclear and Radiological Event Scale was introduced in 1990 by the International Atomic Energy Agency in order to enable prompt communication of safety significance information in case of nuclear accidents....
- Loss-of-coolant accident
- Nuclear meltdownNuclear meltdownNuclear meltdown is an informal term for a severe nuclear reactor accident that results in core damage from overheating. The term is not officially defined by the International Atomic Energy Agency or by the U.S. Nuclear Regulatory Commission...
- Radioactive contaminationRadioactive contaminationRadioactive contamination, also called radiological contamination, is radioactive substances on surfaces, or within solids, liquids or gases , where their presence is unintended or undesirable, or the process giving rise to their presence in such places...
External links
- Chernobyl Nuclear Power Plant - official website
- Chernobyl Nuclear Power Plant at Google Maps
- Construction of the Chernobyl Nuclear Power Plant - video
- Shut down of reactor no. 3 in December 2000 - video
- Slide show of a visit to the Chernobyl reactor in April 2006 by a German TV team joint by Research Center Juelich
- Steel Sarcophagus Announcement.
- «Zone — virtual walk with comments» by Nataliya Monastirnaya
- 25 years of satellite imagery over Chernobyl