Nuclear power

Nuclear power, ornuclear energy, is the use of exothermic nuclear processes, [ 1 ]to generate useful heatand electricity. The term includes nuclear fission, nuclear decayand nuclear fusion. Presently the nuclear fissionof elements in the actinideseries of the periodic tableproduce the vast majority of nuclear energy in the direct service of humankind, with nuclear decayprocesses, primarily in the form of geothermal energy, and radioisotope thermoelectric generators, in niche uses making up the rest. Nuclear (fission) power stations, excluding the contribution from naval nuclear fission reactors, provided about 5.7% of the world's energyand 13% of the world's electricity in 2012. [ 2 ]In 2013, the IAEAreport that there are 437 operational nuclear power reactors, [ 3 ]in 31 countries, [ 4 ]although not every reactor is producing electricity. [ 5 ]In addition, there are approximately 140 naval vessels using nuclear propulsionin operation, powered by some 180 reactors. [ 6 ] [ 7 ] [ 8 ]As of 2013, attaining a net energy gainfrom sustained nuclear fusionreactions, excluding natural fusion power sources such as the Sun, remains an ongoing area of international physicsand engineering research. More than 60 years after the first attempts, commercial fusion power production remains unlikely before 2050. [ 9 ] There is an ongoing debate about nuclear power. [ 10 ] [ 11 ] [ 12 ]Proponents, such as the World Nuclear Association, the IAEAand Environmentalists for Nuclear Energycontend that nuclear power is a safe, sustainableenergy source that reduces carbon emissions. [ 13 ] Opponents, such as Greenpeace Internationaland NIRS, contend that nuclear power poses many threats to people and the environment. [ 14 ] [ 15 ] [ 16 ] Nuclear power plant accidentsinclude the Chernobyl disaster(1986), Fukushima Daiichi nuclear disaster(2011), and the Three Mile Island accident(1979). [ 17 ]There have also been some nuclear submarine accidents. [ 17 ] [ 18 ] [ 19 ]In terms of lives lost per unit of energy generated, analysis has determined that nuclear power has caused less fatalities per unit of energy generated than the other major sources of energy generation. Energy production from coal, petroleum, natural gasand hydropowerhas caused a greater number of fatalities per unit of energy generated due to air pollutionand energy accidenteffects. [ 20 ] [ 21 ] [ 22 ] [ 23 ] [ 24 ]However, the economic costs of nuclear power accidents is high, and meltdowns can take decades to clean up. The human costs of evacuations of affected populations and lost livelihoods is also significant. [ 25 ] [ 26 ] Along with other sustainable energy sources, nuclear power is a low carbon power generationmethod of producing electricity, with an analysis of the literature on its total life cycle emission intensityfinding that it is similar to other renewable sources in a comparison of greenhouse gas(GHG) emissions per unit of energy generated. [ 27 ]With this translating into, from the beginning of nuclear power stationcommercialization in the 1970s, having prevented the emission of approximately 64 gigatonnesof carbon dioxide equivalent(GtCO2-eq) greenhouse gases, gases that would have otherwise resulted from the burning of fossil fuelsin thermal power stations.