What Is Radioactivity ?

Radioactivity exposure has been observed from intentional, industrial sources, such as the Chernobyl disaster of 1986. The 1986 event increased the amount of incident long-lived radioactivity in the environment by 90%, for a cumulative increase of 1100%. Plutonium-239, cesium-137, and iodine-131 are particularly carcinogenic, and have been found in the urine and saliva of the victims.[34]

Environmental impact

Studies have estimated that nuclear energy has increased the global population's standard of living. In terms of the cost of the extraction and production of fossil fuels, the total amount of energy produced by nuclear power has been estimated to be about 18–20% more efficient than the energy provided by fossil fuels. However, the contribution of nuclear power to reduced CO 2 emissions has been estimated to be around 40–60% more efficient.[35] It has also been argued that nuclear power produces less harmful carbon dioxide emissions, as it does not emit sulfur dioxide.[36]

Nuclear power has been estimated to produce about 10% of the total energy used in the United States, despite being responsible for only 3% of primary energy production.[37] The additional energy has been attributed to the fact that electricity generation in the United States largely uses a mix of gas and coal, and nuclear energy produces almost no carbon dioxide or other greenhouse gases, while coal-fired power plants produce up to 90% of the nation's greenhouse gas emissions.

Nuclear power is becoming increasingly important in China, due to the government's move away from polluting, inefficient, and expensive smokestack coal. China has the world's largest installed nuclear power generating capacity (32.4 GWe in 2008), and is a growing nuclear power producer. China is also the world's largest uranium producer and has overtaken Canada as the world's largest producer of mined uranium (947,760 short tons in 2008).[38]

While a number of studies have found an "overstatement" of nuclear power's negative health effects,[39][40][41][42][43][44] there have been also a number of well-designed, well-conducted studies that have come to the opposite conclusion (focusing on specific health risks rather than wider effects).[45][46][47]

As of October 2008, 28 of the world's nuclear reactors are generating power in the U.S., the world's largest nuclear generator.[48] The federal government pays electricity rates that are the third lowest in the world, after Switzerland and Japan, and the lowest among the top 25 electricity producing countries.[49] The only countries paying less are Uruguay, Chile, and Thailand.[50] In Germany, the country with the largest public investment in nuclear power, electricity prices are already about a third higher than the U.S. average.[51] In Sweden, since January 2009, a new levy has been charged on electricity for nuclear power plants.[52] This has raised their production costs by 2%, and lowered their nuclear output by 2%. The charge, originally introduced to fund the operation of the Forsmark I and Forsmark II nuclear power plants, was extended to all nuclear power plants in August 2009.[53]

Concerns about the dangers of nuclear power have been raised by activists and medical professionals, and by many environmental groups.[54][55] These groups include Greenpeace,[56][57] Physicians for Social Responsibility,[58] and the Church of England.[59][60][61][62][63] Nuclear weapons experts and foreign policy experts from the Truman and Kennedy administrations and various foreign governments agree that, compared to traditional energy sources, nuclear power has fewer environmental and health-related problems and has the potential to make the world a safer and more secure place.[64][65]

Nuclear power has been called "a relatively low-carbon, high-efficiency energy source" that can be operated at low cost for long periods of time without producing air, land, or water pollution.[66] Nuclear power plants have significantly lower operating costs than fossil-fuel power plants;[67] nuclear plants account for a third of the nation's

generating capacity (68%) and more than half of the nation's carbon-free electricity generation. A 2013 study in Energy Policy found that "overall the environmental and health costs of nuclear power are lower than [the costs] of fossil fuels, even considering the social costs of nuclear weapons development."[68]

Impact of nuclear accidents 

Major accidents 

Sagan High Powered Reactor Unit 3, built in 1956, overheated in May 1958, and went critical; a fire started, the operator was killed, the reactor core suffered thermal damage, but there was no offsite impact. [73]

May 16, 1954, the Seabrook nuclear power plant accident. A power failure and lack of automatic safety features caused a partial core meltdown of one reactor, releasing about 5 millisieverts of radiation. [74]

May 13, 1979, the Three Mile Island accident. A power failure and a damaged emergency core cooling system were primarily responsible for the accident, but concerns over safety and radiation were also important factors. The plant operator, Exelon Corp., opted not to alert the public until over three