nuclear power plant

• 原子力発電所

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power plant

WordNet

1. place something or someone in a certain position in order to secretly observe or deceive; "Plant a spy in Moscow"; "plant bugs in the dissidents apartment"
2. (botany) a living organism lacking the power of locomotion (同)flora, plant life
3. buildings for carrying on industrial labor; "they built a large plant to manufacture automobiles" (同)works, industrial plant
4. an actor situated in the audience whose acting is rehearsed but seems spontaneous to the audience
5. something planted secretly for discovery by another; "the police used a plant to trick the thieves"; "he claimed that the evidence against him was a plant"
6. put firmly in the mind; "Plant a thought in the students minds" (同)implant
7. put or set (seeds, seedlings, or plants) into the ground; "Lets plant flowers in the garden" (同)set
8. place into a river; "plant fish"
9. supply the force or power for the functioning of; "The gasoline powers the engines"
10. (physics) the rate of doing work; measured in watts (= joules/second)
11. one possessing or exercising power or influence or authority; "the mysterious presence of an evil power"; "may the force be with you"; "the forces of evil" (同)force
12. possession of controlling influence; "the deterrent power of nuclear weapons"; "the power of his love saved her"; "his powerfulness was concealed by a gentle facade" (同)powerfulness
13. make plans for something; "He is planning a trip with his family"
14. scale drawing of a structure; "the plans for City Hall were on file" (同)architectural plan
15. a series of steps to be carried out or goals to be accomplished; "they drew up a six-step plan"; "they discussed plans for a new bond issue" (同)program, programme
16. have the will and intention to carry out some action; "He plans to be in graduate school next year"; "The rebels had planned turmoil and confusion" (同)be after
17. make or work out a plan for; devise; "They contrived to murder their boss"; "design a new sales strategy"; "plan an attack" (同)project, contrive, design
18. of or relating to or constituting the nucleus of an atom; "nuclear physics"; "nuclear fission"; "nuclear forces"
19. (weapons) deriving destructive energy from the release of atomic energy; "nuclear war"; "nuclear weapons"; "atomic bombs" (同)atomic
20. constituting or like a nucleus; "annexation of the suburban fringe by the nuclear metropolis"; "the nuclear core of the congregation"
21. of or relating to or constituting the nucleus of a cell; "nuclear membrane"; "nuclear division"
22. putting seeds or young plants in the ground to grow; "the planting of corn is hard work"
23. the act of fixing firmly in place; "he ordered the planting of policemen outside every doorway"
24. a collection of plants (trees or shrubs or flowers) in a particular area; "the landscape architect suggested a small planting in the northwest corner"

PrepTutorEJDIC

1. (動物に対して)『植物』,草木・(樹木に対して)『草』,草本(そうほん)( 木部があまり発達せず地上部が一年で枯れる植物)・苗,苗木・生産設備,工場,プラント設備,装置・《俗》(人をおとしいれる)わな,おとり / 〈苗など〉‘を'『植える』,〈種〉‘を'まく・(植物を) ‘に'植える《+『名』+『with』+『名』》 / (…に)〈思想など〉‘を'植えつける《+『名』+『in』+『名』》・《場所の副詞[句]を伴って》(ある場所)…‘を'しっかりと置く(すえる,立てる) / ・〈工場・生産設備など〉‘を'建設する・《俗》〈スパイ〉‘を'送りこむ,〈わな〉‘を'仕掛ける・（嫌疑がかかるように）こっそり置く
2. 〈U〉(名身が生れつき備えている,また物事を遂行できる)『能力』,『力』 / 〈U〉(…に対する)権力,支配権《+『over』+『名』》 / 〈C〉(法・官職などによる)権限 / 《複数形で》(生まれながらの)体力,知力,才能 / 〈C〉権力者,実力者;影響力のある集団;強国・大国〈U〉軍事力;国力 / 〈U〉強さ,力 / 〈C〉《通例複数形で》神;悪魔 / 〈U〉動力;工率,仕事率 / 〈U〉(電気などの)エネルギー,力 / 〈C〉(数学で)累乗 / 〈U〉(レンズの)倍率 / 〈U〉《a~》《話》(…の)多数,多量 / 〈機械〉‘に'動力を供給する
3. 『計画』,『案』,プラン,設計 / 『設計図』,『図面』;(小区域の)地図,市街図 / …‘を'『計画する』,‘の'案を立てる / …の設計図をかく,‘を'設計する / 計画を立てる
4. 『核の』,細胞核の / [『原子』]『核の』

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/17 00:38:59」(JST)

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This article is about electricity generation from nuclear power. For the general topic of nuclear power, see Nuclear power.

A nuclear power station (Grafenrheinfeld Nuclear Power Plant, Grafenrheinfeld, Bavaria, Germany). The nuclear reactor is contained inside the spherical containment building in the center - left and right are cooling towers which are common cooling devices used in all thermal power stations, and likewise, emit water vapor from the non-radioactive steam turbine section of the power plant.

Nuclear power plant in Jaslovské Bohunice in Slovakia.

A nuclear power plant is a thermal power station in which the heat source is a nuclear reactor. As is typical in all conventional thermal power stations the heat is used to generate steam which drives a steam turbine connected to an electric generator which produces electricity. As of 23 April 2014, the IAEA report there are 435 nuclear power reactors in operation operating in 31 countries. Nuclear power plants are usually considered to be base load stations, since fuel is a small part of the cost of production.

History

The control room at an American nuclear power plant.

For more history, see nuclear reactor, nuclear power and nuclear fission.

Electricity was generated by a nuclear reactor for the first time ever on September 3, 1948 at the X-10 Graphite Reactor in Oak Ridge, Tennessee in the United States, and was the first nuclear power plant to power a light bulb. The second, larger experiment occurred on December 20, 1951 at the EBR-I experimental station near Arco, Idaho in the United States. On June 27, 1954, the world's first nuclear power plant to generate electricity for a power grid started operations at the Soviet city of Obninsk. The world's first full scale power station, Calder Hall in England opened on October 17, 1956.

Systems

BWR schematic.

Pressurized water reactor

This section has recently been translated from the German Wikipedia.

The conversion to electrical energy takes place indirectly, as in conventional thermal power plants. The fission in a nuclear reactor heats the reactor coolant. The coolant may be water or gas or even liquid metal depending on the type of reactor. The reactor coolant then goes to a steam generator and heats water to produce steam. The pressurized steam is then usually fed to a multi-stage steam turbine. Steam turbines in Western nuclear power plants are among the largest steam turbines ever. After the steam turbine has expanded and partially condensed the steam, the remaining vapor is condensed in a condenser. The condenser is a heat exchanger which is connected to a secondary side such as a river or a cooling tower. The water is then pumped back into the steam generator and the cycle begins again. The water-steam cycle corresponds to the Rankine cycle.

Nuclear reactors

Main article: Nuclear reactor

A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electric energy and for the propulsion of ships.

Nuclear reactors usually rely on uranium to fuel the chain reaction. Uranium is a very heavy metal that is abundant on Earth and is found in sea water as well most rocks. Naturally occurring uranium is found in two different isotopes: uranium-238 (U-238), accounting for 99.3% and uranium-235 (U-235) accounting for about 0.7%. Isotopes are atoms of the same element with a different number of neutrons. Thus, U-238 has 146 neutrons and U-235 has 143 neutrons. Different isotopes have different behaviors. For instance, U-235 is fissile which means that it is easily split and gives off a lot of energy making it ideal for nuclear energy. On the other hand, U-238 does not have that property despite it being the same element. Different isotopes also have different half-lives. A half-life is the amount of time it takes for half of a sample on a radioactive element to decay. U-238 has a longer half-life than U-235, so it takes longer to decay over time. This also means that U-238 is less radioactive than U-235

The nuclear reactor is the heart of the plant. In its central part, the reactor core's heat is generated by controlled nuclear fission. With this heat, a coolant is heated as it is pumped through the reactor and thereby removes the energy from the reactor. Heat from nuclear fission is used to raise steam, which runs through turbines, which in turn powers either ship's propellers or electrical generators.

Since nuclear fission creates radioactivity, the reactor core is surrounded by a protective shield. This containment absorbs radiation and prevents radioactive material from being released into the environment. In addition, many reactors are equipped with a dome of concrete to protect the reactor against both internal casualties and external impacts.

Steam turbine

Main article: Steam turbine

The purpose of the steam turbine is to convert the heat contained in steam into mechanical energy. The engine house with the steam turbine is usually structurally separated from the main reactor building. It is so aligned to prevent debris from the destruction of a turbine in operation from flying towards the reactor.

In the case of a pressurized water reactor, the steam turbine is separated from the nuclear system. To detect a leak in the steam generator and thus the passage of radioactive water at an early stage, an activity meter is mounted to track the outlet steam of the steam generator. In contrast, boiling water reactors pass radioactive water through the steam turbine, so the turbine is kept as part of the control area of the nuclear power plant.

Generator

Main article: Electric generator

The generator converts kinetic energy supplied by the turbine into electrical energy. Low-pole AC synchronous generators of high rated power are used.

Cooling system

A cooling system removes heat from the reactor core and transports it to another area of the plant, where the thermal energy can be harnessed to produce electricity or to do other useful work. Typically the hot coolant is used as a heat source for a boiler, and the pressurized steam from that drives one or more steam turbine driven electrical generators.

Safety valves

In the event of an emergency, safety valves can be used to prevent pipes from bursting or the reactor from exploding. The valves are designed so that they can derive all of the supplied flow rates with little increase in pressure. In the case of the BWR, the steam is directed into the suppression chamber and condenses there. The chambers on a heat exchanger are connected to the intermediate cooling circuit.

Feedwater pump

The water level in the steam generator and nuclear reactor is controlled using the feedwater system. The feedwater pump has the task of taking the water from the condensate system, increasing the pressure and forcing it into either the steam generators (in the case of a pressurized water reactor) or directly into the reactor (for boiling water reactors).

Emergency power supply

Most nuclear plants require two distinct sources of offsite power feeding station service transformers that are sufficiently separated in the plant's switchyard and can receive power from multiple transmission lines. In addition in some nuclear plants the turbine generator can power the plant's house loads while the plant is online via station service transformers which tap power from the generator output bus bars before they reach the step-up transformer (these plants also have station service transformers that receive offsite power directly from the switchyard.) Even with the redundancy of two power sources total loss of offsite power is still possible. Nuclear power plants are equipped with emergency power systems to maintain safety in the event of unit shutdown and loss of offsite power. Batteries provide uninterruptible power to instrumentation, control systems, and valves. Emergency diesel generators provide direct AC power to charge the batteries and to provide power to systems requiring AC power such as motor driven pumps. The emergency diesel generators do not power all plant systems, only those required to shut the reactor down safely, remove decay heat from the reactor, provide emergency core cooling, and, in some plants, spent fuel pool cooling. The large power generation pumps such as the main feedwater, condensate, circulating water, and (in pressurized water reactors) reactor coolant pumps are not backed up by the diesels.

Workers in a nuclear power plant

• Nuclear engineers
• Reactor operators
• Health physicists
• Emergency response team personnel
• Nuclear Regulatory Commission Resident Inspectors

In the United States and Canada, workers except for management, professional (such as engineers) and security personnel are likely to be members of either the International Brotherhood of Electrical Workers (IBEW) or the Utility Workers Union of America (UWUA), or one of the various trades and labor unions representing Machinist, laborers, boilermakers, millwrights, iron workers etc.

Economics

The Bruce Nuclear Generating Station, the largest nuclear power facility in the world

Main article: Economics of new nuclear power plants

The economics of new nuclear power plants is a controversial subject, and multi-billion dollar investments ride on the choice of an energy source. Nuclear power plants typically have high capital costs, but low direct fuel costs, with the costs of fuel extraction, processing, use and spent fuel storage internalized costs. Therefore, comparison with other power generation methods is strongly dependent on assumptions about construction timescales and capital financing for nuclear plants. Cost estimates take into account plant decommissioning and nuclear waste storage or recycling costs in the United States due to the Price Anderson Act. With the prospect that all spent nuclear fuel/"nuclear waste" could potentially be recycled by using future reactors, generation IV reactors, that are being designed to completely close the nuclear fuel cycle.

On the other hand, construction, or capital cost aside, measures to mitigate global warming such as a carbon tax or carbon emissions trading, increasingly favor the economics of nuclear power. Further efficiencies are hoped to be achieved through more advanced reactor designs, Generation III reactors promise to be at least 17% more fuel efficient, and have lower capital costs, while futuristic Generation IV reactors promise 10000-30000% greater fuel efficiency and the elimination of nuclear waste.

In Eastern Europe, a number of long-established projects are struggling to find finance, notably Belene in Bulgaria and the additional reactors at Cernavoda in Romania, and some potential backers have pulled out. Where cheap gas is available and its future supply relatively secure, this also poses a major problem for nuclear projects.

Analysis of the economics of nuclear power must take into account who bears the risks of future uncertainties. To date all operating nuclear power plants were developed by state-owned or regulated utility monopolies where many of the risks associated with construction costs, operating performance, fuel price, and other factors were borne by consumers rather than suppliers. Many countries have now liberalized the electricity market where these risks, and the risk of cheaper competitors emerging before capital costs are recovered, are borne by plant suppliers and operators rather than consumers, which leads to a significantly different evaluation of the economics of new nuclear power plants.

Following the 2011 Fukushima I nuclear accidents, costs are likely to go up for currently operating and new nuclear power plants, due to increased requirements for on-site spent fuel management and elevated design basis threats. However many designs, such as the currently under construction AP1000, use passive nuclear safety cooling systems, unlike those of Fukushima I which required active cooling systems, this largely eliminates the necessity to spend more on redundant back up safety equipment.

Safety and accidents

In his book, Normal accidents, Charles Perrow says that multiple and unexpected failures are built into society's complex and tightly-coupled nuclear reactor systems. Such accidents are unavoidable and cannot be designed around. An interdisciplinary team from MIT has estimated that given the expected growth of nuclear power from 2005 – 2055, at least four serious nuclear accidents would be expected in that period. However the MIT study does not take into account improvements in safety since 1970. To date, there have been five serious accidents (core damage) in the world since 1970 (one at Three Mile Island in 1979; one at Chernobyl in 1986; and three at Fukushima-Daiichi in 2011), corresponding to the beginning of the operation of generation II reactors. This leads to on average one serious accident happening every eight years worldwide.

Complexity

Nuclear power plants are some of the most sophisticated and complex energy systems ever designed. Any complex system, no matter how well it is designed and engineered, cannot be deemed failure-proof. Veteran journalist and author Stephanie Cooke has argued:

The reactors themselves were enormously complex machines with an incalculable number of things that could go wrong. When that happened at Three Mile Island in 1979, another fault line in the nuclear world was exposed. One malfunction led to another, and then to a series of others, until the core of the reactor itself began to melt, and even the world's most highly trained nuclear engineers did not know how to respond. The accident revealed serious deficiencies in a system that was meant to protect public health and safety.

The 1979 Three Mile Island accident inspired Perrow's book Normal Accidents, where a nuclear accident occurs, resulting from an unanticipated interaction of multiple failures in a complex system. TMI was an example of a normal accident because it was "unexpected, incomprehensible, uncontrollable and unavoidable".

Perrow concluded that the failure at Three Mile Island was a consequence of the system's immense complexity. Such modern high-risk systems, he realized, were prone to failures however well they were managed. It was inevitable that they would eventually suffer what he termed a 'normal accident'. Therefore, he suggested, we might do better to contemplate a radical redesign, or if that was not possible, to abandon such technology entirely. .

A fundamental issue contributing to a nuclear power system's complexity is its extremely long lifetime. The timeframe from the start of construction of a commercial nuclear power station through the safe disposal of its last radioactive waste, may be 100 to 150 years.

Failure modes of nuclear power plants

There are concerns that a combination of human and mechanical error at a nuclear facility could result in significant harm to people and the environment:

Operating nuclear reactors contain large amounts of radioactive fission products which, if dispersed, can pose a direct radiation hazard, contaminate soil and vegetation, and be ingested by humans and animals. Human exposure at high enough levels can cause both short-term illness and death and longer-term death by cancer and other diseases.

It is impossible for a commercial nuclear reactor to explode like a nuclear bomb since the fuel is never sufficiently enriched for this to occur.

Nuclear reactors can fail in a variety of ways. Should the instability of the nuclear material generate unexpected behavior, it may result in an uncontrolled power excursion. Normally, the cooling system in a reactor is designed to be able to handle the excess heat this causes; however, should the reactor also experience a loss-of-coolant accident, then the fuel may melt or cause the vessel in which it is contained to overheat and melt. This event is called a nuclear meltdown.

After shutting down, for some time the reactor still needs external energy to power its cooling systems. Normally this energy is provided by the power grid to which that plant is connected, or by emergency diesel generators. Failure to provide power for the cooling systems, as happened in Fukushima I, can cause serious accidents.

Nuclear safety rules in the United States "do not adequately weigh the risk of a single event that would knock out electricity from the grid and from emergency generators, as a quake and tsunami recently did in Japan", Nuclear Regulatory Commission officials said in June 2011.

Vulnerability of nuclear plants to attack

Nuclear reactors become preferred targets during military conflict and, over the past three decades, have been repeatedly attacked during military air strikes, occupations, invasions and campaigns:

• In September 1980, Iran bombed the Al Tuwaitha nuclear complex in Iraq in Operation Scorch Sword.
• In June 1981, an Israeli air strike completely destroyed Iraq's Osirak nuclear research facility in Operation Opera.
• Between 1984 and 1987, Iraq bombed Iran's Bushehr nuclear plant six times.
• On 8 January 1982, Umkhonto we Sizwe, the armed wing of the ANC, attacked South Africa's Koeberg nuclear power plant while it was still under construction.
• In 1991, the U.S. bombed three nuclear reactors and an enrichment pilot facility in Iraq.
• In 1991, Iraq launched Scud missiles at Israel's Dimona nuclear power plant
• In September 2007, Israel bombed a Syrian reactor under construction.

In the U.S., plants are surrounded by a double row of tall fences which are electronically monitored. The plant grounds are patrolled by a sizeable force of armed guards. The NRC's "Design Basis Threat" criterion for plants is a secret, and so what size of attacking force the plants are able to protect against is unknown. However, to scram (make an emergency shutdown) a plant takes fewer than 5 seconds while unimpeded restart takes hours, severely hampering a terrorist force in a goal to release radioactivity.

Attack from the air is an issue that has been highlighted since the September 11 attacks in the U.S. However, it was in 1972 when three hijackers took control of a domestic passenger flight along the east coast of the U.S. and threatened to crash the plane into a U.S. nuclear weapons plant in Oak Ridge, Tennessee. The plane got as close as 8,000 feet above the site before the hijackers’ demands were met.

The most important barrier against the release of radioactivity in the event of an aircraft strike on a nuclear power plant is the containment building and its missile shield. Current NRC Chairman Dale Klein has said "Nuclear power plants are inherently robust structures that our studies show provide adequate protection in a hypothetical attack by an airplane. The NRC has also taken actions that require nuclear power plant operators to be able to manage large fires or explosions—no matter what has caused them."

In addition, supporters point to large studies carried out by the U.S. Electric Power Research Institute that tested the robustness of both reactor and waste fuel storage and found that they should be able to sustain a terrorist attack comparable to the September 11 terrorist attacks in the U.S. Spent fuel is usually housed inside the plant's "protected zone" or a spent nuclear fuel shipping cask; stealing it for use in a "dirty bomb" would be extremely difficult. Exposure to the intense radiation would almost certainly quickly incapacitate or kill anyone who attempts to do so.

Plant location

Fort Calhoun Nuclear Generating Station surrounded by the 2011 Missouri River Floods on June 16, 2011

Angra Nuclear Power Plant in Rio de Janeiro state, Brazil.

In many countries, plants are often located on the coast, in order to provide a ready source of cooling water for the essential service water system. As a consequence the design needs to take the risk of flooding and tsunamis into account. The World Energy Council (WEC) argues disaster risks are changing and increasing the likelihood of disasters such as earthquakes, cyclones, hurricanes, typhoons, flooding. High temperatures, low precipitation levels and severe droughts may lead to fresh water shortages. Failure to calculate the risk of flooding correctly lead to a Level 2 event on the International Nuclear Event Scale during the 1999 Blayais Nuclear Power Plant flood, while flooding caused by the 2011 Tōhoku earthquake and tsunami lead to the Fukushima I nuclear accidents.

The design of plants located in seismically active zones also requires the risk of earthquakes and tsunamis to be taken into account. Japan, India, China and the USA are among the countries to have plants in earthquake-prone regions. Damage caused to Japan's Kashiwazaki-Kariwa Nuclear Power Plant during the 2007 Chūetsu offshore earthquake underlined concerns expressed by experts in Japan prior to the Fukushima accidents, who have warned of a genpatsu-shinsai (domino-effect nuclear power plant earthquake disaster).

Multiple reactors

The Fukushima nuclear disaster illustrated the dangers of building multiple nuclear reactor units close to one another. Because of the closeness of the reactors, Plant Director Masao Yoshida "was put in the position of trying to cope simultaneously with core meltdowns at three reactors and exposed fuel pools at three units".

Nuclear safety systems

Main article: Nuclear safety systems

The three primary objectives of nuclear safety systems as defined by the Nuclear Regulatory Commission are to shut down the reactor, maintain it in a shutdown condition, and prevent the release of radioactive material during events and accidents. These objectives are accomplished using a variety of equipment, which is part of different systems, of which each performs specific functions.

Routine emissions of radioactive materials

For the controversial debate on the health effects by the routine emissions, see Nuclear power debate#Health effects on population near nuclear power plants and workers and Environmental impact of nuclear power#Risk of cancer.

During everyday routine operations, emissions of radioactive materials from nuclear plants are released to the outside of the plants although they are quite slight amounts. The daily emissions go into the air, water and soil.

NRC says, "nuclear power plants sometimes release radioactive gases and liquids into the environment under controlled, monitored conditions to ensure that they pose no danger to the public or the environment", and "routine emissions during normal operation of a nuclear power plant are never lethal".

According to the United Nations (UNSCEAR), regular nuclear power plant operation including the nuclear fuel cycle amounts to 0.0002 millisieverts (mSv) annually in average public radiation exposure; the legacy of the Chernobyl disaster is 0.002 mSv/a as a global average as of a 2008 report; and natural radiation exposure averages 2.4 mSv annually although frequently varying depending on an individual's location from 1 to 13 mSv.

Japanese public perception of nuclear power safety

In March 2012, Prime Minister Yoshihiko Noda said that the Japanese government shared the blame for the Fukushima disaster, saying that officials had been blinded by an image of the country's technological infallibility and were "all too steeped in a safety myth."

Japan has been accused by authors such as journalist Yoichi Funabashi of having an "aversion to facing the potential threat of nuclear emergencies." According to him, a national program to develop robots for use in nuclear emergencies was terminated in midstream because it "smacked too much of underlying danger." Though Japan is a major power in robotics, it had none to send in to Fukushima during the disaster. He mentions that Japan's Nuclear Safety Commission stipulated in its safety guidelines for light-water nuclear facilities that "the potential for extended loss of power need not be considered." However, this kind of extended loss of power to the cooling pumps caused the Fukushima meltdown.

Controversy

Main article: Nuclear power debate

The abandoned city of Prypiat, Ukraine, following the Chernobyl disaster. The Chernobyl nuclear power plant is in the background.

The nuclear power debate is about the controversy which has surrounded the deployment and use of nuclear fission reactors to generate electricity from nuclear fuel for civilian purposes. The debate about nuclear power peaked during the 1970s and 1980s, when it "reached an intensity unprecedented in the history of technology controversies", in some countries.

Proponents argue that nuclear power is a sustainable energy source which reduces carbon emissions and can increase energy security if its use supplants a dependence on imported fuels. Proponents advance the notion that nuclear power produces virtually no air pollution, in contrast to the chief viable alternative of fossil fuel. Proponents also believe that nuclear power is the only viable course to achieve energy independence for most Western countries. They emphasize that the risks of storing waste are small and can be further reduced by using the latest technology in newer reactors, and the operational safety record in the Western world is excellent when compared to the other major kinds of power plants.

Opponents say that nuclear power poses many threats to people and the environment. These threats include health risks and environmental damage from uranium mining, processing and transport, the risk of nuclear weapons proliferation or sabotage, and the unsolved problem of radioactive nuclear waste. They also contend that reactors themselves are enormously complex machines where many things can and do go wrong, and there have been many serious nuclear accidents. Critics do not believe that these risks can be reduced through new technology. They argue that when all the energy-intensive stages of the nuclear fuel chain are considered, from uranium mining to nuclear decommissioning, nuclear power is not a low-carbon electricity source.

Reprocessing

Main article: Nuclear reprocessing

Nuclear reprocessing technology was developed to chemically separate and recover fissionable plutonium from irradiated nuclear fuel. Reprocessing serves multiple purposes, whose relative importance has changed over time. Originally reprocessing was used solely to extract plutonium for producing nuclear weapons. With the commercialization of nuclear power, the reprocessed plutonium was recycled back into MOX nuclear fuel for thermal reactors. The reprocessed uranium, which constitutes the bulk of the spent fuel material, can in principle also be re-used as fuel, but that is only economic when uranium prices are high or disposal is expensive. Finally, the breeder reactor can employ not only the recycled plutonium and uranium in spent fuel, but all the actinides, closing the nuclear fuel cycle and potentially multiplying the energy extracted from natural uranium by more than 60 times.

Nuclear reprocessing reduces the volume of high-level waste, but by itself does not reduce radioactivity or heat generation and therefore does not eliminate the need for a geological waste repository. Reprocessing has been politically controversial because of the potential to contribute to nuclear proliferation, the potential vulnerability to nuclear terrorism, the political challenges of repository siting (a problem that applies equally to direct disposal of spent fuel), and because of its high cost compared to the once-through fuel cycle. In the United States, the Obama administration stepped back from President Bush's plans for commercial-scale reprocessing and reverted to a program focused on reprocessing-related scientific research.

Accident indemnification

The Vienna Convention on Civil Liability for Nuclear Damage puts in place an international framework for nuclear liability. However states with a majority of the world's nuclear power plants, including the U.S., Russia, China and Japan, are not party to international nuclear liability conventions.

In the U.S., insurance for nuclear or radiological incidents is covered (for facilities licensed through 2025) by the Price-Anderson Nuclear Industries Indemnity Act.

Under the Energy policy of the United Kingdom through its Nuclear Installations Act of 1965, liability is governed for nuclear damage for which a UK nuclear licensee is responsible. The Act requires compensation to be paid for damage up to a limit of £150 million by the liable operator for ten years after the incident. Between ten and thirty years afterwards, the Government meets this obligation. The Government is also liable for additional limited cross-border liability (about £300 million) under international conventions (Paris Convention on Third Party Liability in the Field of Nuclear Energy and Brussels Convention supplementary to the Paris Convention).

Decommissioning

Main article: Nuclear decommissioning

Nuclear decommissioning is the dismantling of a nuclear power plant and decontamination of the site to a state no longer requiring protection from radiation for the general public. The main difference from the dismantling of other power plants is the presence of radioactive material that requires special precautions.

Warranty period of operation of nuclear power plants is 30 years. One from factors wear is the destruction of the reactors shell under the action of ionizing radiation.

Generally speaking, nuclear plants were designed for a life of about 30 years. Newer plants are designed for a 40 to 60-year operating life.

Decommissioning involves many administrative and technical actions. It includes all clean-up of radioactivity and progressive demolition of the plant. Once a facility is decommissioned, there should no longer be any danger of a radioactive accident or to any persons visiting it. After a facility has been completely decommissioned it is released from regulatory control, and the licensee of the plant no longer has responsibility for its nuclear safety.

Historic accidents

The 2011 Fukushima Daiichi nuclear disaster in Japan, the worst nuclear accident in 25 years, displaced 50,000 households after radiation leaked into the air, soil and sea. Radiation checks led to bans of some shipments of vegetables and fish.

Main article: Nuclear power accidents by country

The nuclear industry says that new technology and oversight have made nuclear plants much safer, but 57 small accidents have occurred since the Chernobyl disaster in 1986 until 2008. Two thirds of these mishaps occurred in the US. The French Atomic Energy Agency (CEA) has concluded that technical innovation cannot eliminate the risk of human errors in nuclear plant operation.

According to Benjamin Sovacool, an interdisciplinary team from MIT in 2003 estimated that given the expected growth of nuclear power from 2005 – 2055, at least four serious nuclear accidents would be expected in that period. However the MIT study does not take into account improvements in safety since 1970.

Flexibility of nuclear power plants

Nuclear stations are used primarily for base load because of economic considerations. The fuel cost of operations for a nuclear plant is smaller than the fuel cost for operation of coal or gas plants. There is no cost saving if you run a nuclear plant at less than full capacity.

However, nuclear plants are routinely used in load following mode on a large scale in France, although "it is generally accepted that this is not an ideal economic situation for nuclear plants." Unit A at the German Biblis Nuclear Power Plant is designed to in- and decrease its output 15% per minute between 40 and 100% of its nominal power. Boiling water reactors normally have load-following capability, implemented by varying the recirculation water flow.

Future power plants

A new generation of designs for nuclear power plants, known as the Generation IV reactors, are the subject of active research. Many of these new designs specifically attempt to make fission reactors cleaner, safer and/or less of a risk to the proliferation of nuclear weapons. Passively safe plants (such as the ESBWR) are available to be built and other reactors that are designed to be nearly fool-proof are being pursued. Fusion reactors, which are still in the early stages of development, diminish or eliminate some of the risks associated with nuclear fission.

Two 1600 MWe European Pressurized Reactors (EPRs) are being built in Europe, and two are being built in China. The reactors are a joint effort of French AREVA and German Siemens AG, and will be the largest reactors in the world. One EPR is in Olkiluoto, Finland, as part of the Olkiluoto Nuclear Power Plant. The reactor was originally scheduled to go online in 2009, but has been repeatedly delayed, and as of September 2014 has been pushed back to 2018. Preparatory work for the EPR at the Flamanville Nuclear Power Plant in Flamanville, Manche, France was started in 2006, with a scheduled completion date of 2012. The French reactor has also been delayed, and was projected, in 2013, to launch in 2016. The two Chinese EPRs are part of the Taishan Nuclear Power Plant in Taishan, Guangdong. The Taishan reactors were scheduled to go online in 2014 and 2015, but that has been delayed to 2015 and 2016.

As of March 2007, there are seven nuclear power plants under construction in India, and five in China.

In November 2011 Gulf Power stated that by the end of 2012 it hopes to finish buying off 4000 acres of land north of Pensacola, Florida in order to build a possible nuclear power plant.

In 2010 Russia launched the world’s first floating nuclear power plant. The £100 million vessel, the Akademik Lomonosov, is the first of seven plants that will bring vital energy resources to remote Russian regions.

By 2025, Southeast Asia nations would have a total of 29 nuclear power plants, Indonesia will have 4 nuclear power plants, Malaysia 4, Thailand 5 and Vietnam 16 from nothing at all in 2011.

In 2013 China had 32 nuclear reactors under construction, the highest number in the world.

Expansion at two Nuclear Power Plants in the United States, Plant Vogtle and V. C. Summer Nuclear Power Plant, located in Georgia and South Carolina, respectively, are scheduled to be completed between 2016 and 2019. The two new Plant Vogtle reactors, and the two new reactors at Virgil C. Summer Nuclear Plant, represent the first nuclear power construction projects in the United States since the Three Mile Island nuclear accident in 1979.

Several countries have begun Thorium-based nuclear power programs. Thorium is four times more abundant within nature than uranium. Over 60% of thorium's ore monazite is found in five democratically governed countries: Australia, the United States, India, Brazil, and Norway. These thorium resources are enough to power current energy needs for thousands of years. The thorium fuel cycle is able to generate nuclear energy with a lower output of radiotoxic waste than the uranium fuel cycle.

See also

• List of nuclear reactors
• Nuclear power by country
• Nuclear Information and Resource Service
• Fossil-fuel power station
• Gerald W. Brown, American whistleblower on passive fire protection/circuit integrity deficiencies in US and Canadian plants
• Nuclear fuel cycle
• Containment building
• Safety engineering
• SCRAM
• U.S. Federal Emergency Management Agency (FEMA)
• Nuclear Regulatory Commission of the USA
• Auxiliary feedwater
• Uranium market

References

External links

• IPPNW - International Physicians for the Prevention of Nuclear War (Nobel Peace Prize 1985)
• MAPW - Information on Australia's research reactor
• Freeview Video 'Nuclear Power Plants - What's the Problem' A Royal Institution Lecture by John Collier by the Vega Science Trust.
• Non Destructive Testing for Nuclear Power Plants
• Web-based simple nuclear power plant game
• Uranium.Info publishing uranium price since 1968.
• Information about all NPP in the world
• U.S. plants and operators
• SCK.CEN Belgian Nuclear Research Centre in Mol.
• Civil Liability for Nuclear Damage - World Nuclear Association
• Glossary of Nuclear Terms
• Protection against Sabotage of Nuclear Facilities: Using Morphological Analysis in Revising the Design Basis Threat From the Swedish Morphological Society
• Critical Hour: Three Mile Island, The Nuclear Legacy, And National Security Online book by Albert J. Fritsch, Arthur H. Purcell, and Mary Byrd Davis (2005). Updated edition June 2006
• An Interactive VR Panorama of the cooling towers at Temelin Nuclear Power Plant, Czech Republic
• Interactive map with all nuclear power plants US and worldwide (Note: missing many plants)
• Map with all nuclear power plants US and worldwide (Note: active, not active and under construction)

UpToDate Contents

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• 1. 原子力災害後の小児における放射線被曝のマネージメント management of radiation exposure in children following a nuclear disaster
• 2. 小児における放射線被曝の臨床的特徴 clinical features of radiation exposure in children
• 3. 成人における放射線障害の治療 treatment of radiation injury in the adult
• 4. 成人における放射線障害の生物学および臨床的特徴 biology and clinical features of radiation injury in adults
• 5. 放射線誘発性甲状腺癌 radiation induced thyroid cancer

English Journal

• p53 Regulation of Energy Metabolism and Mitochondria Regulation of p53 in Cancer Cells: An Insight into the Role of Manganese Superoxide Dismutase.

• Sun Y, Holley AK, St Clair DK.SourceGraduate Center for Toxicology, 454 HSRB, University of Kentucky, Lexington, KY 40536. dstcl00@uky.edu.
• Current pharmaceutical biotechnology.Curr Pharm Biotechnol.2012 Jun 1. [Epub ahead of print]
• Accumulated evidence suggests that p53 plays an important role in the regulation of metabolism and intracellular redox homeostasis through transcription-dependent and -independent mechanisms. Mitochondria, the power plant of cells, provide cells with ATP for their functions by regulating energy meta
• PMID 22201594

• Validation of the ICRP model for caesium intake by lactating mothers with Italian data after the Chernobyl fallout.

• Giussani A, Risica S.SourceHelmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Medical Radiation Physics and Diagnostics, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
• Environment international.Environ Int.2012 Feb;39(1):122-7. Epub 2011 Nov 17.
• In the aftermath of the Chernobyl nuclear power plant accident, a research group of the Italian National Institute of Health (Istituto Superiore di Sanità) carried out two research programmes on maternal milk. One concerned the transfer of caesium radionuclides from the diet to breast milk. In the
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• Parents' perceptions of water safety and quality.

• Merkel L, Bicking C, Sekhar D.SourcePenn State College of Medicine, Public Health Sciences, 500 University Dr, H108, Hershey, PA, 17033, USA, LMerkel@hmc.psu.edu.
• Journal of community health.J Community Health.2012 Feb;37(1):195-201.
• Every day parents make choices about the source of water their families consume. There are many contributing factors which could affect decisions about water consumption including taste, smell, color, safety, cost, and convenience. However, few studies have investigated what parents with young child
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Japanese Journal

• 循環型社会の虚構と現実(第75回) 原子力発電所と二酸化炭素

• 村田 ？治.
• 月刊廃棄物 = Monthly the waste 38(6), 64-69, 2012-06
• NAID 40019304251

• 島根原子力発電所事故を想定した放射性物質飛散のシュミレーションと避難に関する考察

• 矢倉 はるな,栗政 明弘
• 米子医学雑誌 63(3), 106-120, 2012-05-31
• NAID 120004229645

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★リンクテーブル★

リンク元	「原子力発電所」「power plant」
関連記事	「plan」「power」「nuclear」「plant」「planting」

「原子力発電所」

　　[★]

英

nuclear power plant

関

発電設備

「power plant」

　　[★]

• 発電設備

関

nuclear power plant

「plan」

　　[★]

• n.

• 計画、予定、プラン

• v.

• 計画する、予定する

関

design、destine、enterprise、planning、predetermine、program、programme、project、prospective、schedule、schema、scheme

　 　 　 　 　 　

「power」

　　[★]

• n.

• 力、能力、威力、勢い、(数学)羃乗

• v.

• 力を与える、動力を供給する

関

ability、capability、capacity、competence、competent、energy、facility、force、strength、vigor

　 　 　 　 　

「nuclear」

　　[★]

• adj.

• 核の、(生物)細胞核の、(物理)原子核の

関

cell nuclei、cell nucleus、nuclei、nucleo、nucleus

　 　 　 　 　

「plant」

　　[★]

• n.

• 植物、プラント

関

phyto

　 　 　 　 　 　 　 　 　

「planting」

　　[★]

• n.

• 定植

関

populate