Nuclear Energy

Nuclear power‬
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity,[1] with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity.[2] In 2007, the IAEA reported there were 439 nuclear power reactors in operation in theworld,[3] operating in 31 countries.[4] Also, more than 150 naval vessels using nuclear propulsion have been built.
There is an ongoing debate about the use of nuclear energy.[5][6][7] Proponents, such as the World Nuclear Association and IAEA, contend that nuclear power is a sustainable energy source that reduces carbon emissions.[8] Opponents, such as Greenpeace International and NIRS, believe thatnuclear power poses many threats to people and the environment.[9][10][11]
Nuclear power plant accidents include the Chernobyl disaster (1986), Fukushima Daiichi nuclear disaster (2011), and the Three Mile Island accident (1979).[12] There have also been some nuclear-powered submarine mishaps.[13][14][12] However, the safety record of nuclear power is good when compared with many other energytechnologies.[15] Research into safety improvements is continuing[16] and nuclear fusion may be used in the future.
China has 25 nuclear power reactors under construction, with plans to build many more,[17] while in the US the licenses of almost half its reactors have been extended to 60 years,[18] and plans to build another dozen are under serious consideration.[19] However, Japan's 2011 FukushimaDaiichi nuclear disaster prompted a rethink of nuclear energy policy in many countries.[20] Germany decided to close all its reactors by 2022, and Italy has banned nuclear power.[20] Following Fukushima, the International Energy Agency halved its estimate of additional nuclear generating capacity to be built by 2035.[21]
Use
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,[3] operating in 31 countries.[4] As of December 2009, the world had 436 reactors.[22] Since commercial nuclear energy began in the mid 1950s, 2008 was the first year that no newnuclear power plant was connected to the grid, although two were connected in 2009.[22][23]
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 decrease since 2007 has been the prolonged shutdown of large reactors atthe Kashiwazaki-Kariwa Nuclear Power Plant in Japan following the Niigata-Chuetsu-Oki earthquake.[1]
The United States produces the most nuclear energy, with nuclear power providing 19%[24] of the electricity it consumes, while France produces the highest percentage of its electrical energy from nuclear reactors—80% as of 2006.[25] In the European Union as a whole, nuclear energy provides 30% ofthe electricity.[26] Nuclear energy policy differs among European Union countries, and some, such as Austria, Estonia, Ireland and Italy, have no active nuclear power stations. In comparison, France has a large number of these plants, with 16 multi-unit stations in current use.
In the US, while the coal and gas electricity industry is projected to be worth $85 billion by 2013, nuclear powergenerators are forecast to be worth $18 billion.[27]
Many military and some civilian (such as some icebreaker) ships use nuclear marine propulsion, a form of nuclear propulsion.[28] A few space vehicles have been launched using full-fledged nuclear reactors: the Soviet RORSAT series and the American SNAP-10A.
International research is continuing into safety improvements such as passively safe...