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: See also: Directory:Nuclear

Nuclear power is a type of There was an error working with the wiki: Code[1], There was an error working with the wiki: Code[2]), is concentrated such that nuclear fission takes place in a controlled There was an error working with the wiki: Code[3] and creates There was an error working with the wiki: Code[4] water, produce There was an error working with the wiki: Code[54], and drive a There was an error working with the wiki: Code[55]. The turbine can be used for mechanical work and also to generate electricity. Nuclear power is used to power most military submarines and aircraft carriers and provides 7% of the world's energy and 17% of the world's electricity. The United States produces the most nuclear energy, with nuclear power providing 20% of the electricity it consumes, while There was an error working with the wiki: Code[56] produces the highest percent of its energy from nuclear reactors&mdash80% There was an error working with the wiki: Code[57]. [http://www.npr.org/templates/story/story.php?storyId=5369610

International research is ongoing into various safety improvements, the use of There was an error working with the wiki: Code[5]), for There was an error working with the wiki: Code[6] sea water, and for use in There was an error working with the wiki: Code[58] systems.

Construction of nuclear power plants declined following the 1979 There was an error working with the wiki: Code[7]. Lately, there has been renewed interest in nuclear energy from national governments, the public, and some notable environmentalists due to increased oil prices, new There was an error working with the wiki: Code[59] designs of plants, and the low emission rate of There was an error working with the wiki: Code[60] which some governments need to meet the standards of the There was an error working with the wiki: Code[61]. A few reactors are under construction, and several new types of reactors are planned.

The use of nuclear power is controversial because of the problem of storing There was an error working with the wiki: Code[8] of There was an error working with the wiki: Code[9] plants, that it releases much less radioactive waste than coal power, and that nuclear power is a There was an error working with the wiki: Code[10] believe nuclear power is an uneconomic, unsound and potentially dangerous energy source, especially compared to There was an error working with the wiki: Code[11] operating research reactors and fuel enrichment plants, since those countries refuse adequate There was an error working with the wiki: Code[62] oversight and are believed to be trying to develop nuclear weapons.

History

Origins

The first successful experiment with Nuclear fission was conducted in 1938 in There was an error working with the wiki: Code[63] by the German physicists There was an error working with the wiki: Code[64], There was an error working with the wiki: Code[65] and There was an error working with the wiki: Code[66].

During the There was an error working with the wiki: Code[12], a number of nations embarked on crash programs to develop nuclear energy, focusing first on the development of There was an error working with the wiki: Code[13]. Several nations began their own construction of nuclear reactors at this point, primarily for weapons use, though research was also being conducted into their use for civilian electricity generation.

Electricity was generated for the first time by a nuclear reactor on There was an error working with the wiki: Code[67] There was an error working with the wiki: Code[68] at the There was an error working with the wiki: Code[69] experimental fast breeder station near There was an error working with the wiki: Code[70], which initially produced about 100 kW.

In 1952 a report by the There was an error working with the wiki: Code[71] (The President's Materials Policy Commission) for President There was an error working with the wiki: Code[72] made a "relatively pessimistic" assessment of nuclear power, and called for "aggressive research in the whole field of solar energy". http://www.ieer.org/reports/npd.html

A December 1953 speech by President There was an error working with the wiki: Code[73], "There was an error working with the wiki: Code[74]", set the U.S. on a course of strong government support for the international use of nuclear power.

Early years

On There was an error working with the wiki: Code[14] power plant, There was an error working with the wiki: Code[75] became the world's first nuclear powered city in 1960.

Development

Installed nuclear capacity initially rose relatively quickly, rising from less than 1 There was an error working with the wiki: Code[76] (GW) in 1960 to 100GW in the late 1970s, and 300GW in the late 1980s. Since the late 1980s capacity has risen much more slowly, reaching 366GW in 2005, primarily due to Chinese expansion of nuclear power. Between around 1970 and 1990, more than 50GW of capacity was under construction (peaking at over 150GW in the late 70s and early 80s) — in 2005, around 25GW of new capacity was planned. More than two-thirds of all nuclear plants ordered after January 1970 were eventually cancelled.http://www.iaea.org/About/Policy/GC/GC48/Documents/gc48inf-4_ftn3.pdf

During the 1970s and 1980s rising economic costs (related to vastly extended construction times largely due to regulatory delays) and falling fossil fuel prices made nuclear power plants then under construction less attractive. In the 1980s (U.S.) and 1990s (Europe), flat load growth and There was an error working with the wiki: Code[77] also made the addition of large new baseload capacity unnecessary.

A general movement against nuclear power arose during the last third of the 20th century, based on the fear of a possible There was an error working with the wiki: Code[15], and on the opposition to Nuclear waste production, transport and final storage. Perceived risks on the citizens health and safety, the 1979 accident at There was an error working with the wiki: Code[78] and the There was an error working with the wiki: Code[79] There was an error working with the wiki: Code[80] played a key part in stopping new plant construction in many countries. There was an error working with the wiki: Code[81] (1978), There was an error working with the wiki: Code[82] (1980) and There was an error working with the wiki: Code[83] (1987) voted in referendums to oppose or phase out nuclear power, while opposition in There was an error working with the wiki: Code[84] prevented a nuclear programme there. However, the Brookings Institution suggests in http://www.brookings.edu/comm/policybriefs/pb138.htm that new nuclear units have not been ordered primarily for economic reasons rather than fears of accidents.

Financing for new reactors dried up when Wall Street's enthusiasm ended. Disillusionment was complete when new research discredited the claim (previously accepted as fact even by opponents) that nuclear power was still, despite all its problems, the most cost-effective source of electrity. Industry figures had omitted the factor of downtime. The newest and biggest U.S. plants were actually producing only half the energy they were supposed to, due to shutdowns for refueling, routine maintenance, retrofitting, and frequent minor mishaps. (See Charles Komanoff, "U.S. Nuclear Plant Performance," Bulletin of the Atomic Scientists, November 1980. See also Komanoff's overview of the reasons for the nuclear industry's decline in the critical period from 1973 to 1981, which includes some economic analysis http://www.komanoff.net/nuclear_power/10_blows.php)

As of 2006, the stated desire to use nuclear power for electricity generation has been suspected of being a cover for There was an error working with the wiki: Code[85] in There was an error working with the wiki: Code[86] and There was an error working with the wiki: Code[87].

Current and planned use

: For more details, see There was an error working with the wiki: Code[88]

In 2005, there were 441 commercial nuclear generating units throughout the world, with a total capacity of about 368 gigawatts.111 reactors (36GW) have been shut down.<pesn type= 80% of reactors (and of generating capacity) are more than 15 years old.[http://www.iaea.org/cgi-bin/db.page.pl/pris.reaopag.htm"></pesn>

In 2006 in the United States, there were 104 (69 pressurized water reactors and 35 boiling water reactors) commercial nuclear generating units licensed to operate, producing a total of 101,289 megawatts (electric), which is approximately 20 percent of the nation's total electric energy consumption. The United States is the world's largest supplier of commercial nuclear power. Future development of nuclear power in the U.S. (see the There was an error working with the wiki: Code[89]) was enabled by the There was an error working with the wiki: Code[90] As of 2005, no nuclear plant had been ordered without subsequent cancellation for over twenty years, thus the desire for programs to promote new construction. However, on <pesn type= it was announced that two sites in the U.S. had been selected to receive new power reactors (exclusive of the new power reactor scheduled for There was an error working with the wiki: Code[92]). Since then, other utilities have taken steps towards ordering new nuclear reactors.

In There was an error working with the wiki: Code[16] was generated by 58 nuclear reactors, the highest share in the world. France closed its last coal mine in April 2004, and currently relies on fossil energy for less than 10% of its electricity production. There was an error working with the wiki: Code[93], the world's second most nuclear-dependent nation, generates 70% of its power (1185 MWe) from a nuclear reactor. However, this is mostly a testament to the country's low power demand, as Lithuania runs only a single 1500MWe There was an error working with the wiki: Code[94]-2 at its There was an error working with the wiki: Code[95].http://www.ce-review.org/99/9/nuke_huang9.html

There was an error working with the wiki: Code[96] is presently constructing more than 10 civilian nuclear power reactors - the highest in the world.

There was an error working with the wiki: Code[17] are currently planning or building new nuclear reactors or reopening old ones. There was an error working with the wiki: Code[97], There was an error working with the wiki: Code[98], There was an error working with the wiki: Code[99], There was an error working with the wiki: Code[100], There was an error working with the wiki: Code[101], There was an error working with the wiki: Code[102], There was an error working with the wiki: Code[103], There was an error working with the wiki: Code[104], There was an error working with the wiki: Code[105], There was an error working with the wiki: Code[106], United Kingdom and There was an error working with the wiki: Code[107], are considering doing this. There was an error working with the wiki: Code[108], There was an error working with the wiki: Code[109], Germany, There was an error working with the wiki: Code[110], There was an error working with the wiki: Code[111], There was an error working with the wiki: Code[112], There was an error working with the wiki: Code[113], There was an error working with the wiki: Code[114], There was an error working with the wiki: Code[115], There was an error working with the wiki: Code[116], and There was an error working with the wiki: Code[117] have nuclear reactors but currently no advanced proposals for expansion. <pesn type=http://www.wired.com/wired/archive/12.09/china.html." str="[[Belgium"></pesn>], Germany, There was an error working with the wiki: Code[119], There was an error working with the wiki: Code[115], and There was an error working with the wiki: Code[116] have decided on a There was an error working with the wiki: Code[122].

According to the There was an error working with the wiki: Code[123] and the There was an error working with the wiki: Code[124], nuclear power is projected to have a slightly declining 5-10% share of world energy production until 2025, assuming that fossil fuel production can continue to expand rapidly (which is controversial). See There was an error working with the wiki: Code[125].

The 1600MW There was an error working with the wiki: Code[18] FIN5 reactor being built in There was an error working with the wiki: Code[126], There was an error working with the wiki: Code[127], will be the largest in the world. The project is led by Areva while Siemens will deliver the reactor. FIN5 will not be ready for commercial operation until the second quarter of 2010.

Reactor types

Current technology

There are two types of nuclear power sources via There was an error working with the wiki: Code[128]s in current use:

# The There was an error working with the wiki: Code[19] produces heat through a controlled There was an error working with the wiki: Code[20] of There was an error working with the wiki: Code[21] and There was an error working with the wiki: Code[22]. All reactors will be compared to the Pressurized Water Reactor (PWR), as that is the standard modern reactor design.The difference between There was an error working with the wiki: Code[23] and There was an error working with the wiki: Code[24] reactors will be covered later. In general, fast-spectrum reactors will produce less waste, and the waste they do produce will have a vastly shorter There was an error working with the wiki: Code[25], whereas thermal reactors generally cannot.

# A. There was an error working with the wiki: Code[129]s (PWR)

#: These are reactors cooled and moderated by high pressure, liquid (even at extreme temperatures) water. They are the majority of current reactors, and are generally considered the safest and most reliable technology, although There was an error working with the wiki: Code[26] is a reactor of this type. This is a There was an error working with the wiki: Code[130] reactor design.

# B. There was an error working with the wiki: Code[131]s (BWR)

#: These are reactors cooled and moderated by water, under slightly lower pressure. The water is allowed to boil in the reactor. The thermal efficiency of these reactors can be higher, and they can be simpler, and even potentially more stable and safe. Unfortunately, the boiling water puts more stress on many of the components, and increases the risk that radioactive water may escape in an accident. These reactors make up a substantial percentage of modern reactors. This is a thermal neutron reactor design.

# C. There was an error working with the wiki: Code[132] (PHWR)

#: A There was an error working with the wiki: Code[27] design, (known as There was an error working with the wiki: Code[28]-cooled and -moderated Pressurized-Water reactors. Instead of using a single large containment vessel as in a PWR, the fuel is contained in hundreds of pressure tubes. These reactors are fuelled with natural There was an error working with the wiki: Code[133] and are thermal neutron reactor designs. PHWRs can be refueled while at full power, which makes them very efficient in their use of uranium (it allows for precise flux control in the core). Most PHWR's exist within Canada, but units have been sold to There was an error working with the wiki: Code[134], There was an error working with the wiki: Code[135], There was an error working with the wiki: Code[136] (pre-NPT), There was an error working with the wiki: Code[137] (pre-NPT), There was an error working with the wiki: Code[138], and There was an error working with the wiki: Code[139]. India also operates a number of PHWR's, often termed 'CANDU-derivatives', built after the 1974 There was an error working with the wiki: Code[140] nuclear weapon test.

# D. There was an error working with the wiki: Code[141]s

#: A Soviet Union design, built to produce plutonium as well as power, the dangerous and unstable RBMKs are water cooled with a There was an error working with the wiki: Code[29] was an RBMK.

# E. Gas Cooled Reactor (GCR) and There was an error working with the wiki: Code[30] (AGCR)

#: These are generally graphite moderated and There was an error working with the wiki: Code[31] cooled. They have a high thermal efficiency compared with PWRs and an excellent safety record. There are a number of operating reactors of this design, mostly in the United Kingdom. Older designs (i.e. There was an error working with the wiki: Code[142] stations) are either shut down or will be in the near future. However the AGCRs have an anticipated life of a further 10 to 20 years. This is a thermal neutron reactor design.

# F. There was an error working with the wiki: Code[32] (SCWR)

#: This is a theoretical reactor design that is part of the There was an error working with the wiki: Code[33], until there is no difference between the liquid and gas states. A CWR is similar to a BWR, except there is no boiling (as the water is critical), and the thermal efficiency is higher as the water behaves more like a classical gas. This is an epithermal neutron reactor design.

# G. There was an error working with the wiki: Code[34] There was an error working with the wiki: Code[35] (LMFBR)

#: This is a reactor design that is cooled by liquid metal, and totally unmoderated. These reactors can function much like a PWR in terms of efficiency, and don't require much high pressure containment, as the liquid metal doesn't need to be kept at high pressure, even at very high temperatures. There was an error working with the wiki: Code[36] in the United States. The There was an error working with the wiki: Code[143] reactor in Japan suffered a sodium leak in 1995 and is approved for restart in There was an error working with the wiki: Code[144]. All three use/used liquid There was an error working with the wiki: Code[145]. These reactors are There was an error working with the wiki: Code[146], not thermal neutron designs. These reactors come in two types:

#: There was an error working with the wiki: Code[37]

#:: Using There was an error working with the wiki: Code[147] as the liquid metal provides excellent radiation shielding, and allows for operation at very high temperatures. Also, lead is (mostly) transparent to neutrons, so fewer neutrons are lost in the coolant, and the coolant does not become radioactive. Unlike sodium, lead is mostly inert, so there is less risk of explosion or accident, but such large quantities of lead may be problematic from toxicology and disposal points of view. Often a reactor of this type would use a There was an error working with the wiki: Code[148] mixture. In this case, the bismuth would present some minor radiation problems, as it is not quite as transparent to neutrons, and can be transmuted to a radioactive isotope more readily than lead.

#: There was an error working with the wiki: Code[38]

#:: Most LMFBRs are of this type. The sodium is relatively easy to obtain and work with, and it also manages to actually remove corrosion on the various reactor parts immersed in it. However, sodium explodes violently when exposed to water, so care must be taken, but such explosions wouldn't be vastly more violent than (for example) a leak of superheated fluid from a CWR or PWR.

# The There was an error working with the wiki: Code[149] produces heat through passive There was an error working with the wiki: Code[150].

#: Some radioisotope thermoelectric generators have been created to power space probes (for example, the There was an error working with the wiki: Code[39] probe), some There was an error working with the wiki: Code[151]s in the former There was an error working with the wiki: Code[152], and some There was an error working with the wiki: Code[153]s. The heat output of these generators diminishes with time the heat is converted to electricity by Thermocouples.

How it works

Nuclear energy is produced by atomic fission. A large atom (usually uranium or plutonium) breaks into two smaller ones, releasing energy and neutrons. The neutrons then trigger further break-ups. And so on. If this “chain reaction? can be controlled, the energy released can be used to boil water, produce steam and drive a turbine that generates electricity. If it runs away, the result is a meltdown and an accident (or, in extreme circumstances, a nuclear explosion—though circumstances are never that extreme in a reactor because the fuel is less fissile than the material in a bomb).

In many new designs the neutrons, and thus the chain reaction, are kept under control by passing them through water to slow them down. (Slow neutrons trigger more break ups than fast ones.) This water is exposed to a pressure of about 150 atmospheres—a pressure that means it remains liquid even at high temperatures. When nuclear reactions warm the water, its density drops, and the neutrons passing through it are no longer slowed enough to trigger further reactions. That negative feedback stabilises the reaction rate.

Experimental technologies

A number of other designs for nuclear power generation, the There was an error working with the wiki: Code[154]s, are the subject of active research and may be used for practical power generation in the future. A number of the advanced nuclear reactor designs could also make critical fission reactors much cleaner, much safer and/or much less of a risk to the proliferation of nuclear weapons.

There was an error working with the wiki: Code[155] - The link at the end of this paragraph references an interview with Dr. Charles Till, former director of Argonne National Laboratory West in Idaho and outlines the Integral Fast Reactor and its advantages over current reactor design, especially in the areas of safety, efficient nuclear fuel usage and reduced waste. The IFR was built, tested and evaluated during the 1980s and then retired under the Clinton administration in the 1990s due to nuclear non-proliferation policies of the administration. Recycling spent fuel is the core of its design and it therefore produces a fraction of the waste of current reactors. http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html

There was an error working with the wiki: Code[156] - This reactor type is designed so high temperatures reduce power output by There was an error working with the wiki: Code[157] of the fuel's neutron cross-section. It uses ceramic fuels so its safe operating temperatures exceed the power-reduction temperature range. Most designs are cooled by inert helium, which cannot have steam explosions, and which does not easily absorb neutrons and become radioactive, or dissolve contaminants that can become radioactive. Typical designs have more layers (up to 7) of passive containment than light water reactors (usually 3). A unique feature that might aid safety is that the fuel-balls actually form the core's mechanism, and are replaced one-by-one as they age. The design of the fuel makes fuel reprocessing expensive.

There was an error working with the wiki: Code[158], Small, Sealed, Transportable, Autonomous Reactor is being primarily researched and developed in the US, intended as a fast breeder reactor that is tamper resistant, passively safe.

There was an error working with the wiki: Code[159]s are designed to be safer and more stable, but pose a number of engineering and economic difficulties.

Controlled There was an error working with the wiki: Code[160] could in principle be used in There was an error working with the wiki: Code[161] plants to produce safer, cleaner power, but significant scientific and technical obstacles remain. Several fusion reactors have been built, but as yet none has 'produced' more thermal energy than electrical energy consumed. Despite research having started in the 1950s, no commercial fusion reactor is expected before 2050 The [[ITER] project is currently leading the effort to commercialize fusion power.

Thorium based reactors

:It is possible to convert Thorium-232 into U-233 in reactors specially designed for the purpose. In this way, Thorium , which is more plentiful than uranium, can be used to breed U-233 nuclear fuel. U-233 is also believed to have favourable nuclear properties as compared to traditionally used U-235, including better neutron economy and lower production of long lived transuranic waste.

:There was an error working with the wiki: Code[162] - A proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. Under development in the There was an error working with the wiki: Code[163] (BARC).

:There was an error working with the wiki: Code[40] and There was an error working with the wiki: Code[164] Uses thorium.

:India is also building a bigger scale FBTR or fast breeder thorium reactor to harness the power with the use of thorium.

Life cycle

In the There was an error working with the wiki: Code[41] using various techniques. At this point, the enriched uranium, containing more than the natural 0.7% U-235, is used to make rods of the proper composition and geometry for the particular reactor that the fuel is destined for. The fuel rods will spend about 3 years inside the reactor, generally until about 3% of their uranium has been fissioned, then they will be moved to a There was an error working with the wiki: Code[165] where the short lived isotopes generated by fission can decay away. After about 5 years in a cooling pond, the spent fuel is radioactively cool enough to handle, and it can be moved to dry storage casks or reprocessed.

Fuel resources

There was an error working with the wiki: Code[42], occurring almost everywhere on land and in the oceans. It is about as common as There was an error working with the wiki: Code[166], and 500 times more common than There was an error working with the wiki: Code[167]. Most types of rocks and soils contain uranium, although often in low concentrations. At present, the There was an error working with the wiki: Code[168] shows the economically viable deposits are regarded as being those with concentrations of at least 0.1 per cent uranium. At this cost level, available reserves would last for 50 years at the present rate of use. Doubling the price of uranium, which would have only little effect on the overall cost of nuclear power, would increase reserves to hundreds of years. To put this in perspective a doubling in the cost of natural uranium would increase the total cost of nuclear power 5 per cent. On the other hand, if the price of natural gas was doubled, the cost of gas-fired power would increase by about 60 per cent. Doubling the price of coal would increase the cost of power production in a large coal-fired power station by about 30 per cent.http://www.analys.se/fakta/fakta36eng.pdf

Current There was an error working with the wiki: Code[169]s make relatively inefficient use of nuclear fuel, leading to energy waste. More efficient reactor designs or There was an error working with the wiki: Code[170] http://www.world-nuclear.org/info/inf04.htm would reduce the amount of waste material generated and allow better use of the available resources.

As opposed to current light water reactors which use There was an error working with the wiki: Code[171] (0.7% of all natural uranium), There was an error working with the wiki: Code[172]s use There was an error working with the wiki: Code[173] (99.3% of all natural uranium). It has been estimated that there is anywhere from 10,000 to five billion years worth of uranium-238 for use in these power plants Breeder technology has been used in several reactors <pesn type=. Currently (December 2005), the only breeder reactor producing power is BN-600 http://eng.rosatom.ru/?razdel=160" str="in Beloyarsk, Russia. (The electricity output of BN-600 is 600 MW - Russia has planned to build another unit, BN-800, at Beloyarsk nuclear power plant.) Also, Japan's [[Monju"></pesn>] reactor is planned for restart (having been shut down since 1995), and both China and India intend to build breeder reactors.

Another alternative would be to use uranium-233 bred from There was an error working with the wiki: Code[174] as fission fuel - the There was an error working with the wiki: Code[175]. Thorium is three times more abundant in the Earth's crust than uranium http://www.world-nuclear.org/info/inf62.htm, and (theoretically) all of it can be used for breeding, making the potential thorium resource orders of magnitude larger than the uranium fuel cycle operated without breeding. Unlike the breeding of U-238 into plutonium, fast breeder reactors are not necessary - it can be performed satisfactorily in more conventional plants.

Proposed There was an error working with the wiki: Code[176]s assume the use of There was an error working with the wiki: Code[177], an There was an error working with the wiki: Code[178] of Hydrogen, as fuel and in most current designs also There was an error working with the wiki: Code[179]. Assuming a fusion energy output equal to the current global output and that this does not increase in the future, then the known current lithium reserves would last 3,000 years, lithium from sea water would last 60 million years, and a more complicated fusion process using only deuterium from sea water would have fuel for 150 billion years. For comparison, the [[Sun] has an estimated remaining life of 5 billion years.

Reprocessing

:For more details on this topic, see There was an error working with the wiki: Code[180]

Reprocessing can recover up to 95% of the remaining uranium and plutonium in spent nuclear fuel, putting it into new There was an error working with the wiki: Code[181]. Reprocessing of civilian fuel from power reactors is currently done on large scale in England, France and (formerly) Russia, will be in China and perhaps India, and is being done on an expanding scale in Japan. There was an error working with the wiki: Code[182] has announced its intention to complete the nuclear fuel cycle via reprocessing, a move which has led to criticism from the United States and the International Atomic Energy Agency. http://news.bbc.co.uk/1/hi/world/middle_east/4031603.stm Reprocessing of civilian nuclear fuel is not done in the United States due to proliferation concerns.

Solid waste

Nuclear power produces spent fuel, a unique solid waste problem referred as There was an error working with the wiki: Code[43] of the radioactive There was an error working with the wiki: Code[183]s in the waste. In fact, fresh spent fuel is so radioactive that less than a minute's exposure to it will cause death. However, spent nuclear fuel becomes less radioactive over time - after 40 years, the There was an error working with the wiki: Code[184] is 99.9% lower than it was the moment the reactor was last shut offhttp://www.world-nuclear.org/education/ne/ne5.htm, although still dangerously radioactive.

Spent fuel is primarily composed of unconverted uranium, as well as significant quantities of transuranic actinides (plutonium and curium, mostly). In addition, about 3% of it is made of There was an error working with the wiki: Code[185]s. The actinides (uranium, plutonium, and curium) are responsible for the bulk of the long term radioactivity, whereas the fission products are responsible for the bulk of the short term radioactivity. It is possible through reprocessing to separate out the actinides and use them again for fuel, but this often requires special fast spectrum reactors, which produce a reduction in long term radioactivity within the remaining waste. In any case, the remaining waste will be substantially radioactive for at least 300 years even if the actinides are removed, and for up to thousands of years if the actinides are left in. Even in the most optimistic scenarios, complete consumption of all actinides, and using fast spectrum reactors to destroy some of the long-lived non-actinides as well, the waste must be segregated from the environment for at least several hundred years, and therefore this is properly categorized as a long-term problem. There are, however, chemical plants which also produce hazardous waste staying in the environment for hundreds of years.

A large nuclear reactor produces 3 cubic metres (25-30 tonnes) of spent fuel each year.<pesn type= had accumulated about 49,000 metric tons of spent nuclear fuel from nuclear reactors. Unlike other countries, U.S. policy forbids recycling of used fuel and it is all treated as waste. After 10,000 years of radioactive decay, according to There was an error working with the wiki: Code[187] standards, the spent nuclear fuel will no longer pose a threat to public health and safety.

The safe storage and disposal of nuclear waste is a difficult challenge. Because of potential harm from radiation, spent nuclear fuel must be stored in shielded basins of water, or in dry storage vaults or There was an error working with the wiki: Code[188] until its radioactivity decreases naturally ("decays") to safe levels. This can take days or thousands of years, depending on the type of fuel. Most waste is currently stored in temporary storage sites, requiring constant maintenance, while suitable permanent disposal methods are discussed. Underground storage at There was an error working with the wiki: Code[189] in U.S. has been proposed as permanent storage. See the article on the There was an error working with the wiki: Code[190] for more information.

The nuclear industry produces a volume of low-level radioactive waste in the form of contaminated items like clothing, hand tools, water purifier resins, and (upon decommissioning) the materials of which the reactor itself is built. In the United States, the There was an error working with the wiki: Code[191] has repeatedly attempted to allow low-level materials to be handled as normal waste: landfilled, recycled into consumer items, etc. Much low-level waste releases very low levels of radioactivity and is essentially considered radioactive waste because of its history. For example, according to the standards of the NRC, the radiation released by coffee is enough to treat it as low level waste. Overall, nuclear power produces far less waste material than fossil-fuel based power plants. There was an error working with the wiki: Code[192]-burning plants are particularly noted for producing large amounts of radioactive ash due to concentrating naturally occurring radioactive material in the coal.

In addition, the nuclear industry fuel cycle produces many tons of There was an error working with the wiki: Code[193] (DU) which consists of U-238 with the easily fissile U-235 isotope removed. U-238 is a tough metal with several commercial uses, for example aircraft production, radiation shielding, and for making bullets and armor as it has a higher density than There was an error working with the wiki: Code[194]. There are concerns that U-238 may lead to health problems in groups exposed to this material excessively, like tank crews and civilians living in areas where large quantities of DU ammunition have been used.

The amounts of waste can be reduced in several ways. Both There was an error working with the wiki: Code[195] and There was an error working with the wiki: Code[196]s can reduce the amounts of waste and increase the amount of energy gained per fuel unit. There was an error working with the wiki: Code[197]s or There was an error working with the wiki: Code[198] could greatly reduce the time the waste has to be stored http://www.world-nuclear.org/info/inf35.htm. Subcritical reactors may also be able to do the same to already existing waste. It has been argued that the best solution for the nuclear waste is above ground temporary storage since technology is rapidly changing. The current waste may well become valuable fuel in the future, particularly if it is not reprocessed, as in the U.S.

In countries with nuclear power, radioactive wastes comprise less than 1% of total industrial toxic wastes, which remain hazardous indefinitely unless it decomposes or is treated so that it is less toxic or non-toxic. http://www.world-nuclear.org/info/inf04.htm.

Economy

Opponents of nuclear power argue that any of the environmental benefits are outweighed by safety compromises and by the costs related to construction and operation of nuclear power plants, including costs for spent-fuel disposal and plant retirement. Proponents of nuclear power respond that nuclear energy is the only power source which explicitly factors the estimated costs for waste containment and plant decommissioning into its overall cost, and that the quoted cost of fossil fuel plants is deceptively low for this reason. The cost of some renewables would be increased too if they included necessary back-up due to their intermittent nature.

A UK Royal Academy of Engineering report in 2004 looked at electricity generation costs from new plants in the UK. In particular it aimed to develop "a robust approach to compare directly the costs of intermittent generation with more dependable sources of generation". This meant adding the cost of standby capacity for wind, as well as carbon values up to £30 (€45.44) per tonne CO2 for coal and gas. Wind power was calculated to be more than twice as expensive as nuclear power. Without a carbon tax, the cost of production through coal, nuclear and gas ranged £0.022-0.026/There was an error working with the wiki: Code[199] and coal gasification was £0.032/kWh. When carbon tax was added (up to £0.025) coal came close to onshore wind (including back-up power) at £0.054/kWh - offshore wind is £0.072/kWh.

Nuclear power remained at £0.023/kWh either way, as it produces negligible amounts of CO2. Nuclear figures included decommissioning costs.http://www.countryguardian.net/generation_costs_report.pdfhttp://www.world-nuclear.org/info/inf02.htmhttp://web.mit.edu/nuclearpower/

In one study, certain Gas There was an error working with the wiki: Code[200] plants were calculated to be three to four times more cost-effective than nuclear power, if all the heat produced was used onsite or in a local heating system. However, the study estimated only 25 year plant lifetimes (60 is now common), 68% capacity factors were assumed (above 90% is now common), other conservatisms were applied, and nuclear power also produces heat which could be used in similar ways (although most nuclear power plants are located in remote areas). The study then found similar costs for nuclear power and most other forms of generation if not including external costs (such as back-up power). http://www.oeko.de/service/gemis/files/info/nuke_co2_en.pdf

Capital costs

Generally, a nuclear power plant is significantly more expensive to build than an equivalent coal-fuelled or gas-fuelled plant. However, coal is significantly more expensive than nuclear fuel, and natural gas significantly more expensive than coal - thus, capital costs aside, natural gas-generated power is the most expensive.

In many countries, licensing, inspection and certification of nuclear power plants has added delays and construction costs to their construction. In the U.S. many new regulations were put in place after the There was an error working with the wiki: Code[201] partial meltdown. Building gas-fired or coal-fired plants has not had these problems. Because a power plant does not yield profits during construction, longer construction times translated directly into higher interest charges on borrowed construction funds. However, the regulatory processes for siting, licensing, and constructing have been standardized since their introduction, to make construction of newer and safer designs more attractive to companies.

In There was an error working with the wiki: Code[202] and There was an error working with the wiki: Code[203], construction costs and delays are significantly diminished because of streamlined government licensing and certification procedures. In France, one model of reactor was type-certified, using a There was an error working with the wiki: Code[204] process similar to the process used to certify aircraft models for safety. That is, rather than licensing individual reactors, the regulatory agency certified a particular design and its construction process to produce safe reactors. U.S. law permits type-licensing of reactors, a process which is about to be used. http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/01-11-2006/0004246911&EDATE=.

To encourage development of nuclear power, under the There was an error working with the wiki: Code[44] (DOE) has offered interested parties the opportunity to introduce France's model for licensing and to subsidize 25% to 50% of the construction cost overruns due to delays for the first six new plants. Several applications were made, two sites have been chosen to receive new plants, and other projects are pending.

Operating costs

In general, coal and nuclear plants have the same types of operating costs (operations and maintenance plus fuel costs). However, nuclear and coal differ in the relative size of those costs. Nuclear has lower fuel costs but higher operating and maintenance costs. In recent times in the United States savings due to lower fuel cost have not been low enough for nuclear to repay its higher investment cost. Thus new nuclear reactors have not been built in the United States. Coal's operating cost advantages have only rarely been sufficient to encourage the construction of new coal based power generation. Around 90 to 95 percent of new power plant construction in the United States has been natural gas-fired.

To be competitive in the current market, both the nuclear and coal industries must reduce new plant investment costs and construction time. The burden is clearly greater for nuclear producers than for coal producers, because investment costs are higher for nuclear plants. Operation and maintenance costs are particularly important because they represent a large portion of costs for nuclear power.

One of the primary reasons for the uncompetitiveness of the U.S. nuclear industry has been the lack of any measure that provides an economic incentive to reduce carbon emissions (There was an error working with the wiki: Code[205]). Many economists and environmentalists have called for a mechanism to take into account the negative externalities of coal and gas consumption. In such an environment, it is argued that nuclear will become cost-competitive in the United States.

Subsidies

Critics of nuclear power claim that it is the beneficiary of inappropriately large economic subsidies — mainly taking the forms of taxpayer-funded research and development and limitations on disaster liability — and that these subsidies, being subtle and indirect, are often overlooked when comparing the economics of nuclear against other forms of power generation. However, competing energy sources also receive subsidies. Fossil fuels receive large direct and indirect subsidies, like tax benefits and not having to pay for their pollution Renewables receive large direct production subsidies and tax breaks in many nations [http://www.world-nuclear.org/info/inf68.htm.

Energy research and development (R&D) for nuclear power has and continues to receive much larger state subsidies than R&ampD for renewable energy or fossil fuels. However, today most of this takes places in Japan and France: in most other nations renewable R&D get more money. In the U.S., public research money for nuclear fission declined from 2,179 to 35 million dollars between 1980 to 2000 - however, in order to restart the industry, the next six U.S. reactors will receive subsidies equal to those of renewables and, in the event of cost overruns due to delays, at least partial compensation for the overruns (see [[Nuclear Power 2010 Program]).

According to the There was an error working with the wiki: Code[45], insurance for nuclear or radiological incidents in the There was an error working with the wiki: Code[46] extended this Act to newer facilities. In the United Kingdom, the There was an error working with the wiki: Code[206] of 1965 governs liability for nuclear damage for which a UK nuclear licensee is responsible. The There was an error working with the wiki: Code[207] puts in place an international framework for nuclear liability.

Other economic issues

Nuclear Power plants tend to be most competitive in areas where other fuel resources are not readily available - France, most notably, has almost no native supplies of fossil fuels.The province of <pesn type=, according to the government's There was an error working with the wiki: Code[209], no further nuclear power stations are to be built, due to the high cost per unit of nuclear power, compared to fossil fuels.However, the British government's chief scientific advisor [[David King (scientist)|David King] reports that building one more generation of nuclear power plants may be necessary.China tops the list of planned new plants, due to its rapidly expanding economy and fervent construction in many types of energy projects.[http://tauon.nuc.berkeley.edu/asia/2000/XuMi.pdf

Most new gas-fired plants are intended for peak supply. The larger nuclear and coal plants cannot quickly adjust their instantaneous power production, and are generally intended for baseline supply. The market price for baseline power has not increased as rapidly as that for peak demand. Some new experimental reactors, notably There was an error working with the wiki: Code[47], are specifically designed for peaking power.

Any effort to construct a new nuclear facility around the world, whether an older design or a newer experimental design, must deal with There was an error working with the wiki: Code[210] objections. Given the high profile of both the Three Mile Island and Chernobyl accidents, few municipalities welcome a new nuclear reactor, processing plant, transportation route, or experimental nuclear burial ground within their borders, and many have issued local ordinances prohibiting the development of nuclear power. However, a few U.S. areas with nuclear units are campaigning for more (see There was an error working with the wiki: Code[211]).

Current nuclear reactors return around 40-60 times the invested energy when using life cycle analysis. This is better than coal, natural gas, and current renewables except hydropower.http://www.world-nuclear.org/info/inf11.htm

The There was an error working with the wiki: Code[212] gives other reasons why nuclear power plants may not be economical.http://www.rmi.org/sitepages/pid305.php In the U.S. this includes long lead times on risky investments, and the more cost-effective approach of investing in efficiency instead of new power plants.

Nuclear power, There was an error working with the wiki: Code[213], and Wind power are currently the only realistic large scale energy sources that would be able to replace oil and natural gas after a peak in global oil and gas production has been reached (see There was an error working with the wiki: Code[214]). However, The Rocky Mountain Institute claims that in the U.S. increases in transportation efficiency and stronger, lighter cars would replace most oil usage with what it calls There was an error working with the wiki: Code[215]s.http://www.oilendgame.com Biofuels can then substitute for a significant portion of the remaining oil use. Efficiency, insulation, solar thermal, and solar photovoltaic technologies can substitute for most natural gas usage after a peak in production.

Nuclear proponents often assert that renewable sources of power have not solved problems like intermittent output, high costs, and diffuse output which requires the use of large surface areas and much construction material and which increases distribution losses. For example, studies in Britain have shown that increasing wind power production contribution to 20% of all energy production, without costly pumped hydro or electrolysis/fuel cell storage, would only reduce coal or nuclear power plant capacity by 6.7% (from 59 to 55 GWe) since they must remain as backup in the absence of power storage. Nuclear proponents often claim that increasing the contribution of intermittent energy sources above that is not possible with current technology.Some renewable energy sources, such as solar, overlap well with peak electricial production and reduce the need of spare generating capacity. Future applications that use electricity when it is available (e.g. for pressurizing water systems, desalination, or hydrogen generation) would help to reduce the spare generation capacity required by both nuclear and renewable energy sources.[http://www.energy.ca.gov/2005_energypolicy/index.html

Risks

Some opponents of nuclear power, such as There was an error working with the wiki: Code[48] of There was an error working with the wiki: Code[49]. Recently, some opponents have softened their stance on nuclear power since it is currently the only mature technology used in the production of electricity that does not create greenhouse gases and therefore does not contribute to global warming.

Other critics of nuclear power, who may not necessarily oppose it as a viable source of energy, point out that industry oversight and compliance with safety regulations is often not up to par. Such critics include the There was an error working with the wiki: Code[216], the Nuclear Information and Research Service, The There was an error working with the wiki: Code[217], There was an error working with the wiki: Code[218], The Nuclear Control Institute, and many others, as well as renowned physicists such as Dr. There was an error working with the wiki: Code[219].

According to a 1978 finding by the Supreme Court of the United States, comprehensive testing and study had not yet removed the risk of a major nuclear accident In the 1980s and 1990s each U.S. nuclear plant underwent an Individual Plant Examination process using [[probabilistic risk assessment] to quantify the risks and identify and address high-risk areas.

To highlight what they believe are the risks, opponents quote the situation in the United States, where under the There was an error working with the wiki: Code[220] corporations requested and were granted immunity beyond (in There was an error working with the wiki: Code[221]) $10 billion (all the available insurance plus pool monies combined) from civil liability (including from possible criminal behavior, although that would be subject to criminal prosecution) from a nuclear incident which causes harm to the public. (Beyond the $10 billion, Congress is required by law to act.)

Proponents argue that the risks are small and that fear has been the single largest obstacle to the widespread use of nuclear power. Assessment of nuclear risk was last done in the 1991 There was an error working with the wiki: Code[222] report. Additionally, competing technologies may have equivalent risks. There was an error working with the wiki: Code[223] currently contributes significantly to problems like There was an error working with the wiki: Code[224], There was an error working with the wiki: Code[225], various diseases due to airborne pollution, and the storage of large amounts of ash. Contrary to popular belief, coal power actually results in more radioactive waste being released into the environment than nuclear power though the health risks of the coal-based radioactive release is small [http://greenwood.cr.usgs.gov/energy/factshts/163-97/FS-163-97.html, particularly when compared with the hazards of other pollutants from coal burning.

Accident or attack

Opponents argue that a major disadvantage of the use of nuclear reactors is the threat of a There was an error working with the wiki: Code[50] or terrorist attack and the possible resulting exposure to radiation.

Proponents argue that the potential for a meltdown in non-Russian-designed reactors is very small due to the care taken in designing adequate safety systems, and that the nuclear industry has much better statistics regarding humans deaths from occupational accidents than coal or hydropower While the <pesn type=, meaning that a malfunction could result in ever-increasing generation of heat and radiation until the reactor was breached. Even at There was an error working with the wiki: Code[226], the most severe civilian nuclear accident in the non-Soviet world, the reactor vessel and containment building were never breached so that very little radiation (well below natural background radiation levels) was released into the environment.

Design changes are being pursued in the hope of lessening some of the risks of fission reactors in particular, automated and There was an error working with the wiki: Code[227] designs are being pursued. Fusion reactors which may come to exist in the future theoretically have little risk since the fuel contained in the reaction chamber is only enough to sustain the reaction for about a minute, whereas a fission reactor contains about a year's supply of fuel. Subcritical reactors never have a self sustained nuclear chain reaction.

Opponents of nuclear power express concerns that nuclear waste is not well protected, and that it can be released in the event of terrorist attack, quoting a 1999 Russian incident where workers were caught trying to sell 5 grams of radioactive material on the open market or the incident in 1993 where Russian workers were caught selling 4.5 kilograms of enriched uranium.<pesn type= http://www.guardian.co.uk/international/story/0,3604,526856,00.htmlhttp://www.axisglobe.com/article.asp?article=328" str=" The There was an error working with the wiki: Code[52] terrorist attacks.Spent fuel is usually housed inside the plant's stealing it for use in a "dirty bomb" is extremely difficult - somewhat ironically, because the exposure to the intense radiation would almost certainly quickly incapacitate and kill any terrorists who attempt to do so.[http://www.thebulletin.org/article.php?art_ofn=jf04koch"></pesn>

According to the There was an error working with the wiki: Code[228], 20 American States have requested stocks of There was an error working with the wiki: Code[229] which the NRC suggests should be available for those living within 10 miles of a nuclear power plant in the unlikely event of a severe accident.http://www.nrc.gov/what-we-do/emerg-preparedness/protect-public/potassium-iodide.html

Health effects on populations near nuclear plants

Most of the human exposure to radiation comes from natural There was an error working with the wiki: Code[230]. Most of the remaining exposure comes from medical procedures. Several large studies in the U.S., Canada, and Europe have found no evidence of any increase in cancer mortality among people living near nuclear facilities. For example, in 1990, the There was an error working with the wiki: Code[231] (NCI) of the There was an error working with the wiki: Code[232] announced that, after doing a large-scale study which evaluated the mortality rates from 16 types of cancer, no increased incidence of cancer mortality was found for people living near 62 nuclear installations in the United States. The study also showed no increase in the incidence of childhood There was an error working with the wiki: Code[233] mortality in the study of surrounding counties after the start-up of the nuclear facilities. The NCI study, the broadest of its kind ever conducted, surveyed 900,000 cancer deaths in counties near nuclear facilities.

Aside from the immediate effects of the Chernobyl accident (see above), there is continuing impact from soils containing radioactivity in There was an error working with the wiki: Code[234] and There was an error working with the wiki: Code[235]. For this reason a There was an error working with the wiki: Code[236] was established around the Chernobyl plant.

In March, 2006, safety reviews found that several nuclear plants in the United States have been leaking water contaminated with There was an error working with the wiki: Code[237] into the ground, which will likely eventually drain into rivers.The attorney general of Illinois announced she was filing a lawsuit against [[Exelon] because of six such leaks, demanding that the utility provide substitute water supplies to residents although no well outside company property shows levels that exceed drinking water standards. According to the NRC, "The inspection determined that public health and safety has not been adversely affected and the dose consequence to the public that can be attributed to current onsite conditions is negligible with respect to NRC regulatory limits." However, the chairman of the [[Nuclear Regulatory Commission], said, "They're going to have to fix it."

Nuclear proliferation

Opponents of nuclear power point out that nuclear technology is often There was an error working with the wiki: Code[53], and much of the same materials and knowledge used in a civilian nuclear program can be used to develop There was an error working with the wiki: Code[238]s. This concern is known as There was an error working with the wiki: Code[239] and is a major reactor design criterion.

The military and civil purposes for nuclear energy are intertwined in most countries with nuclear capabilities. In the U.S., for example, the first goal of the Department of Energy is "to advance the national, economic, and energy security of the United States to promote scientific and technological innovation in support of that mission and to ensure the environmental cleanup of the national nuclear weapons complex." http://www.energy.gov/about/index.htm

The enriched uranium used in most nuclear reactors is not concentrated enough to build a bomb. Most nuclear reactors run on 4% enriched uranium There was an error working with the wiki: Code[240] used 90% enriched uranium while lower enrichment levels could be used, the minimum bomb size would rapidly become infeasibly large as the level was decreased. However, the technology used to enrich uranium for power generation could be used to make the highly enriched uranium needed to build a bomb.

In addition, the plutonium produced in power reactors, if concentrated through reprocessing, can be used for a bomb. While the plutonium resulting from normal reactor fuelling cycles is less than ideal for weapons use because of the concentration of Pu-240, a usable weapon can be produced from it. http://www.npec-web.org/Reports/Report041022%20LWR.pdf If the reactor is operated on very short fuelling cycles, bomb-grade plutonium can be produced.

It is widely believed that the nuclear programs of India and Pakistan used CANDU reactors to produce fissionable materials for their weapons however, this is not true. India used a research reactor named CIRUS, based on the Canadian NRX designPakistan is believed to have produced the material for its weapons from an indigenous enrichment program [http://www.fas.org/nuke/guide/pakistan/nuke/chron.htm.

To prevent weapons proliferation, safeguards on nuclear technology were published in the There was an error working with the wiki: Code[241] (NPT) and monitored since 1968 by the There was an error working with the wiki: Code[242] (IAEA). Nations signing the treaty are required to report to the IAEA what nuclear materials they hold and their location. They agree to accept visits by IAEA auditors and inspectors to verify independently their material reports and physically inspect the nuclear materials concerned to confirm physical inventories of them in exchange for access to nuclear materials and equipment on the global market.

Several states did not sign the treaty and were able to use international nuclear technology (often procured for civilian purposes) to develop nuclear weapons (There was an error working with the wiki: Code[243], There was an error working with the wiki: Code[244], There was an error working with the wiki: Code[245], and There was an error working with the wiki: Code[246]). South Africa has since signed the NPT, and now holds the distinction of being the only known state to have indigenously produced nuclear weapons, and then verifiably dismantled themOf those who have signed the treaty and received shipments of nuclear paraphernalia, many states have either claimed to or been accused of attempting to use supposedly civilian nuclear power plants for developing weapons, including <pesn type=. Certain types of reactors are more conducive to producing nuclear weapons materials than others, and a number of international disputes over proliferation have centered on the specific model of reactor being contracted for in a country suspected of nuclear weapon ambitions.

New technology, like There was an error working with the wiki: Code[248], may lessen the risk of nuclear proliferation by providing sealed reactors with a limited self-contained fuel supply and with restrictions against tampering.

One possible obstacle for expanding the use of nuclear power might be a limited supply of uranium ore, without which it would become necessary to build and operate breeder reactors. However, at current usage there is sufficient uranium for an extended period - "In summary, the actual recoverable uranium supply is likely to be enough to last several hundred (up to 1000) years, even using standard reactors." (see Fuel resources above). Breeder reactors have been banned in the U.S. since President [[Jimmy Carter]'s administration prohibited reprocessing because of what it regarded as the unacceptable risk of proliferation of weapons-grade materials.

Some proponents of nuclear power agree that the risk of nuclear proliferation may be a reason to prevent nondemocratic developing nations from gaining any nuclear technology but argue that this is no reason for democratic developed nations to abandon their nuclear power plants. Especially since it seems that democracies never make war against each other (See the There was an error working with the wiki: Code[249]).

Proponents also note that nuclear power, like some other power sources, provides steady energy at a consistent price without competing for energy resources from other countries, something that may contribute to wars.

In February, 2006, a new U.S. initiative, the There was an error working with the wiki: Code[250] was announced - it would be an international effort to reprocess fuel in a manner making proliferation infeasible, while making nuclear power available to developing countries.

Environmental effects

Air pollution

Non-radioactive water vapour is the only significant operating emission from nuclear power plants Fission produces gases such as <pesn type=-85 which have to be stored on-site for several half-lives until they have decayed to safe levels.

Nuclear generation does not directly produce sulphur dioxide, nitrogen oxides, mercury or other pollutants associated with the combustion of fossil fuels. (Pollution from fossil fuels is blamed for many deaths ea

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