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Nuclear power        is the u of sustained nuclear fission to generate heat and do uful work. Nuclear Electric Plants, Nuclear Ships and Submarines u controlled nuclear energy to heat water and produce steam, while in space, nuclear energy decays naturally in a radioisotope thermoelectric generator. Scientists are experimenting with fusion energy for future generation, but the experiments do not currently generate uful energy.                                                                      Cattenom Nuclear Power Plant        Nuclear power provides about 6% of the world's energy and 13–14% of the world's electricity,[1] with the U.S.考研英语复习经验, France, and Japan together accounting for about 50% of nuclear generated electricity.[2] Also, more than 150 naval vesls using nuclear propulsion have been built.                                Nuclear power is controversial and there is an ongoing debate about the u of nuclear energy.[3][4][5] Proponents, such as the World Nuclear Association and IAEA, contend that nuclear power is a sustainable energy source that reduces carbon emissions.[6] Opponents, such as Greenpeace International and motorNIRS, believe that nuclear power pos many threats to people and the environment.[7][8][9]                                                  Some rious nuclear and radiation accidents have occurred. Nuclear power plant accident

s include the Chernobyl disaster (1986), Fukushima I nuclear accidents (2011), and the Three Mile Island accident (1979).[10] Nuclear-powered submarine mishaps include the K-19 reactor accident (1961),[11] the K-27 reactor accident (1968),[12] and the K-431 reactor accident (1985).[10] International rearch is continuing into safety improvements such as passively safe plants,[13]李世默ted演讲 and the possible future u of nuclear fusion.

chillingU                                              Historical and projected world energy u by energy source, 1980-2030, Source: International Energy Outlook 2007, EIA.      Nuclear power installed capacity and generation, 1980 to 2007 (EIA).  The status of nuclear power global                  As of 2005, nuclear power provided 6.3% of the world's energy and 15% of the world's electricity, with the U.S., France, and Japan together accounting for 56.5% of nuclear generated electricity.[2] In 2007, the IAEA reported there were 439 nuclear power reactors in operation in the world,[14] operating in 31 countries.[15] As of December 2009, the world had 436 reactors.[16]格拉姆 Since commercial nuclear energy began in the mid 1950s, 2008 was the first year that no new nuclear power plant was con

nected to the grid, although two were connected in 2009.[16][17]                                                    Annual generation of nuclear power has been on a slight downward trend since 2007, decreasing 1.8% in 2009 to 2558 TWh with nuclear power meeting 13–14% of the world's electricity demand.[1] One factor in the nuclear power percentage decrea since 2007 has been the prolonged shutdown of large reactors at the Kashiwazaki-Kariwa Nuclear Power Plant in Japan following the Niigata-Chuetsu-Oki earthquake.fromdust[1]

The United States produces the most nuclear energy, with nuclear power providing 19%[18] of the electricity it consumes, while France produces the highest percentage of its electrical energy from nuclear reactors—80% as of 2006.[19] In the European Union as a whole, nuclear energy provides 30% of the electricity.[20] Nuclear energy policy differs among European Union countries, and some, such as Austria, Estonia, and Ireland, have no active nuclear power stations. In comparison, France has a large number of the plants, with 16 multi-unit stations in current u.

In the US, while the coal and gas electricity industry is projected to be worth $85 billion by

2013, nuclear power generators are forecast to be worth $18 billion.[21]            Many military and some civilian (such as some icebreaker) ships u nuclear marine propulsion, a form of nuclear propulsionmassa.[22] A few space vehicles have been launched using full-fledged nuclear reactors: the Soviet RORSAT ries and the American SNAP-10A.        International rearch is continuing into safety improvements such as passively safe plants,[23] the u of nuclear fusion, and additional us of process heat such as hydrogen production (in support of a hydrogen economy), for desalinating a water, and for usdistrict h                                                      Flexibility of nuclear power plants                                                                  亵渎怎么读音It is often claimed that nuclear stations are inflexible in their output, implying that other forms of energy would be required to meet peak demand. While that is true for the vast majority of reactors, this is no longer true of at least some modern designs.[68]英语教案网                                                                       Nuclear plants are routinely ud in load following mode on a large scale in France.[69] Unit A at the German Biblis Nuclear Power Plant is designed to in- and decrea his output 15 % per minute between 40 and 100 % of it's nominal power.[70] Boiling water reactors normally h

ave load-following capability, implemented by varying the recirculation water flow.[citation needed]

Life cycle                                                                          The nuclear fuel cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel, (1) which is delivered to a nuclear power plant. After usage in the power plant, the spent fuel is delivered to a reprocessing plant (2) or to a final repository (3) for geological disposition. In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant    A nuclear reactor is only part of the life-cycle for nuclear power. The process starts with mining (e Uranium mining). Uranium mines are underground, open-pit, or in-situ leach mines. In any ca, the uranium ore is extracted, usually converted into a stable and compact form such as yellowcake, and then transported to a processing facility. Here, the yellowcake is converted to uranium hexafluoride, which is then enriched using various techniques. At this point, the enriched uranium, containing more than the natural 0.7% U-235, is ud to make rods of the proper composition and geometry for the particu

lar reactor that the fuel is destined for. The fuel rods will spend about 3 operational cycles (typically 6 years total now) inside the reactor, generally until about 3% of their uranium has been fissioned, then they will be moved to a spent fuel pool where the short lived isotopes generated by fission can decay away. After about 5 years in a spent fuel pool the spent fuel is radioactively and thermally cool enough to handle, and it can be moved to dry storage casks or reprocesd.