The advantages and disadvantages of nuclear energy they are a fairly common debate in today's society, which is clearly divided into two camps. Some argue that it is a reliable and cheap energy, while others warn of disasters that can cause its misuse.
Nuclear energy or atomic energy is obtained through the process of nuclear fission, which consists of bombarding a uranium atom with neutrons so that it divides in two, releasing large amounts of heat that is then used to generate electricity.
The first nuclear power plant was inaugurated in 1956 in the United Kingdom. According to Castells (2012), in 2000 there were 487 nuclear reactors that produced a quarter of the world's electricity. Currently six countries (USA, France, Japan, Germany, Russia and South Korea) concentrate almost 75% of nuclear electricity production (Fernández and González, 2015).
Many people think that atomic energy is very dangerous thanks to famous accidents like Chernobyl or Fukushima. However, there are those who consider this type of energy as "clean" because it has very few greenhouse gas emissions..
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Uranium is the element that is commonly used in nuclear plants to produce electricity. This has the property of storing huge amounts of energy.
Just one gram of uranium is equivalent to 18 liters of gasoline, and one kilo produces approximately the same energy as 100 tons of coal (Castells, 2012).
In principle, the cost of uranium seems to be much more expensive than that of oil or gasoline, but if we take into account that only small amounts of this element are required to generate significant amounts of energy, in the end the cost becomes lower even than that of fossil fuels.
A nuclear power plant has the quality of operating all the time, 24 hours a day, 365 days a year, to supply electricity to a city; This is thanks to the fact that the fuel refill period is every year or 6 months depending on the plant..
Other types of energies depend on a constant supply of fuel (such as coal-fired power plants), or are intermittent and limited by climate (such as renewable sources).
Atomic energy can help governments meet their GHG emission reduction commitments. The operation process in the nuclear plant does not emit greenhouse gases since it does not require fossil fuels.
However, the emissions that occur occur throughout the life cycle of the plant; construction, operation, extraction and milling of uranium and dismantling of the nuclear power plant. (Sovacool, 2008).
Of the most important studies that have been done to estimate the amount of CO2 released by nuclear activity, the average value is 66 g CO2e / kWh. Which is a higher emission value than other renewable resources but is still lower than the emissions generated by fossil fuels (Sovacool, 2008).
A nuclear plant requires little space compared to other types of energy activities; only requires a relatively small area for the installation of the rector and cooling towers.
On the contrary, wind and solar energy activities would require large areas to produce the same energy as a nuclear plant throughout its useful life..
The waste generated by a nuclear plant is extremely dangerous and harmful to the environment. However, the quantity of these is relatively small if we compare it with other activities, and adequate security measures are used, they can remain isolated from the environment without representing any risk..
There are many problems yet to be solved when it comes to atomic energy. However, in addition to fission, there is another process called nuclear fusion, which consists of joining two simple atoms to form a heavy atom.
The development of nuclear fusion, aims to use two hydrogen atoms to produce one of helium and generate energy, this is the same reaction that occurs in the sun.
For nuclear fusion to occur, very high temperatures and a powerful cooling system are necessary, which poses serious technical difficulties and is therefore still in the development phase..
If implemented, it would imply a cleaner source since it would not produce radioactive waste and would also generate much more energy than that currently produced by fission of uranium..
Historical data from many countries show that, on average, no more than 50-70% of uranium could be extracted in a mine, since uranium concentrations lower than 0.01% are no longer viable, as it requires processing a greater quantity of rocks and the energy used is greater than the one that could be generated in the plant. In addition, uranium mining has a deposit extraction half-life of 10 ± 2 years (Dittmar, 2013).
Dittmar proposed a model in 2013 for all existing and planned uranium mines until 2030, in which a global uranium mining peak of 58 ± 4 kton is obtained around the year 2015 to later be reduced to a maximum of 54 ± 5 kton by 2025 and, to a maximum of 41 ± 5 kton around 2030.
This amount will no longer be sufficient to power existing and planned nuclear power plants for the next 10-20 years (Figure 1).
Nuclear energy alone does not represent an alternative to fuels based on oil, gas and coal, since 10,000 nuclear power plants will be needed to replace the 10 terawatts that are generated in the world from fossil fuels. As data, in the world there are only 486.
It takes a lot of investment of money and time to build a nuclear plant, they usually take more than 5 to 10 years from construction start to commissioning, and delays are very common at all new plants (Zimmerman , 1982).
In addition, the period of operation is relatively short, approximately 30 or 40 years, and an extra investment is required for the dismantling of the plant..
The processes related to nuclear energy depend on fossil fuels. The nuclear fuel cycle not only involves the power generation process at the plant, it also consists of a series of activities ranging from the exploration and exploitation of uranium mines to the decommissioning and dismantling of the nuclear plant..
Uranium mining is a very harmful activity for the environment, since to obtain 1 kg of uranium it is necessary to remove more than 190,000 kg of earth (Fernández and González, 2015).
In the United States, uranium resources in conventional deposits, where uranium is the main product, are estimated at 1,600,000 tons of substrate, from which 250,000 tons of uranium can be recovered (Theobald, et al. 1972)
Uranium is mined on the surface or underground, crushed, and then leached into sulfuric acid (Fthenakis and Kim, 2007). The waste that is generated contaminates the soil and water of the place with radioactive elements and contributes to the deterioration of the environment.
Uranium carries significant health risks in workers who are dedicated to its extraction. Samet et al. Concluded in 1984 that uranium mining is a greater risk factor for developing lung cancer than cigarette smoking.
When a plant ends its operations, it is necessary to start the decommissioning process to ensure that future uses of the land do not pose radiological risks to the population or the environment..
The dismantling process consists of three levels and a period of about 110 years is required for the land to be free from contamination. (Gold, 2008).
At present there are about 140,000 tons of radioactive waste without any type of surveillance which were dumped in between 1949 and 1982 in the Atlantic Trench, by the United Kingdom, Belgium, Holland, France, Switzerland, Sweden, Germany and Italy (Reinero, 2013, Fernández and González, 2015). Taking into account that the useful life of uranium is thousands of years, this represents a risk for future generations..
Nuclear power plants are built with strict safety standards and their walls are made of concrete several meters thick to isolate radioactive material from the outside..
However, it is not possible to claim that they are 100% safe. Over the years, there have been several accidents that to date imply that atomic energy represents a risk to the health and safety of the population..
On March 11, 2011, an earthquake hit 9 on the Richter Scale on the east coast of Japan causing a devastating tsunami. This caused extensive damage to the Fukushima-Daiichi nuclear plant, whose reactors were seriously affected..
Subsequent explosions inside the reactors released fission products (radionuclides) into the atmosphere. Radionuclides quickly attached to atmospheric aerosols (Gaffney et al., 2004), and subsequently traveled great distances around the world alongside air masses due to the great circulation of the atmosphere. (Lozano, et al. 2011).
In addition to this, a large amount of radioactive material was spilled into the ocean and, to this day, the Fukushima plant continues to release contaminated water (300 t / d) (Fernández and González, 2015).
The Chernobyl accident occurred on April 26, 1986, during an evaluation of the plant's electrical control system. The catastrophe exposed 30,000 people living near the reactor to about 45 rem of radiation each, roughly the same level of radiation experienced by survivors of the Hiroshima bomb (Zehner, 2012).
During the initial period after the accident, the most biologically significant isotopes released were radioactive iodines, mainly iodine 131 and other short-lived iodides (132, 133).
Absorption of radioactive iodine by ingestion of contaminated food and water and by inhalation resulted in serious internal exposure to people's thyroid gland..
During the 4 years after the accident, medical examinations detected substantial changes in the functional status of the thyroid in exposed children, especially those under 7 years of age (Nikiforov and Gnepp, 1994).
According to Fernández and González (2015), it is very difficult to separate the civilian from the military nuclear industry since the waste from nuclear power plants, such as plutonium and depleted uranium, are raw material in the manufacture of nuclear weapons. Plutonium is the basis for atomic bombs, while uranium is used in projectiles.
The growth of nuclear power has increased the ability of nations to obtain uranium for nuclear weapons. It is well known that one of the factors that lead several countries without nuclear energy programs to express interest in this energy is the basis that such programs could help them develop nuclear weapons. (Jacobson and Delucchi, 2011).
A large-scale global increase in nuclear power facilities can put the world at risk from a potential nuclear war or terrorist attack. To date, the development or attempted development of nuclear weapons in countries such as India, Iraq and North Korea has been secretly carried out at nuclear power facilities (Jacobson and Delucchi, 2011).
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