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Science

Why do We Have to Bet for Nuclear Energy

Climate change is surpassing us. Nine of the ten hottest years that have been recorded have occurred during the last decade, and although records of this data begin in 1880, temperature reconstructions based on the plant and geological record suggest that these last years may have been the hottest for centuries or even millennia. And, above, now it seems that we could be reaching an irreversible climate change situation.

Given the current context, we can not afford to ignore nuclear energy, because now we need it more than ever.

This post has nothing to do with economic interests, nor with ideologies, nor with politics. In fact, I precisely defend nuclear energy because I care about the environment and I think it is the only technology that can avoid the climatic catastrophe that we are heading towards.

Therefore, I would like you to consider the information in this entry, based on figures and not on personal opinions. It is possible that at the end of the article you find that nuclear energy is a very valuable ally and not the agent of the apocalypse who like to paint the sensationalist media.

Before starting, I recommend you to watch the following video:

Let’s start

First of all, nuclear power plants have the great advantage that they generate a very little  amount of Carbon Dioxide (CO2), the gas that is the main responsible for the warming of our planet and that will cause more ecological and economic damage than any other byproduct of the human activity to date.

“Maybe a low amount of carbon dioxide emision makes nuclear power plants a better option than coal or natural gas, but they still produce CO2 anyway. I prefer to cover the energy needs of the planet using a source free of greenhouse gas emissions, such as solar or wind, thanks.”

With the previous conclusion, there is a fact that you have not considered: all the forms of energy generation are associated with carbon dioxide emissions, including renewable ones. In fact, proportionally, nuclear power plants emit less CO2 than solar panels and are similar to hydroelectric and wind power.

How is a nuclear power plant going to emit less CO2 than a photovoltaic or wind power plant? Do you see that solar panels or turbines emit CO2?

Well, that’s right, believe it or not.

This is because, like any other device designed to produce energy, solar panels and wind turbines have to be built: you have to mine the materials from the ground, process them, manufacture the machines and transport those machines to the place where will be installed … And throughout the process fossil fuels are used that, of course, emit carbon dioxide.

Therefore, to calculate how efficient a technology must take into account all the emissions it produces since it is manufactured until it is no longer used and then compare this figure with the amount of energy it generates throughout its useful life . For this reason, the efficiency of an energy source is usually quantified in terms of the tons of CO2 that it will have emitted for each gigawatt-hour (GWh) of energy that it has generated at the end of its life (1 GWh is more or less the energy that consume 700,000 homes).

Although they do not produce CO2 while they are in operation, solar panels generate a small quantity of energy compared to the emissions associated with their construction. As a result, they proportionally emit more CO2 than nuclear or hydroelectric plants, which also do not produce greenhouse gases while they are active and which, in addition, generate large amounts of energy that more than compensate for the carbon dioxide emitted when they are manufactured. In other words, if you want to use solar panels to generate as much energy as a nuclear power plant, you will end up emitting a greater amount of greenhouse gases.

Another great advantage that nuclear power plants have over renewable energies is that they are a very compact source of energy. For example, it is necessary to cover an area of ​​between 16 and 24 square kilometers with solar panels to produce as much energy as a modest 1 GW nuclear power plant. In comparison, a nuclear power plant occupies an average of 3.3 square kilometers… In addition, the photovoltaic plant will only produce that amount of energy in optimal conditions and will not work at night, while the nuclear plant will provide that energy in constantly.

Wind turbines share this same problem: although they are more efficient than solar panels in terms of emissions, between 333 and 667 turbines (with a separation of several hundred meters between each one) are needed to generate as much energy as a power plant 1 GW nuclear power And, again, the turbines will only produce that amount of energy when the conditions are ideal.

The rhetoric that we should bet on a 100% renewable future is a populist tool, when they are really very inefficient methods of producing energy. I’m not saying that renewables do not have a niche market as complementary energy sources on a small scale, such as installing solar panels on the roofs of buildings. My argument is that it is a bad idea to use these technologies to supply the energy demand on a large scale because they use plenty of space compared to the small amount of energy they produce and their CO2 emissions are similar or superior to those of nuclear energy. And, more importantly, they can not be adapted to the energy demand at any given time because the amount of energy they produce depends on the changing climatic conditions.

That is why it is a pity that, given the current context, nuclear energy is demonized:

“A clean and compact technology that produces plenty of energy in a continuous way.”

But maybe people are against nuclear energy because radioactive waste is not as clean as you think.

In one thing I agree, many people get to worry when they hear about radioactive waste, but I think it is precisely because they have a wrong idea of ​​what nuclear fuel is, how it is managed and what are its risks. And I think that lack of information comes from the fact that most of the population does not know what radiation is exactly or why radioactive material is used as fuel.

I will explain what nuclear waste is, so you can see that it has nothing to do with the commonly prejudged idea.

To produce energy, nuclear power plants use rods composed of small solid cylinders of enriched uranium dioxide stacked inside zircon tubes. A set of rods forms a fuel element.

nuclear fuelA

What does it mean that uranium is enriched?

On Earth, Uranium can be found in nature by forming minerals such as torbernite or uraninite. Uranium ore that is extracted from the soil contains two isotopes of this element: uranium-235, which represents 0.7% of atoms, and uranium-238, which makes up the remaining 99.3%. 235 and 238 simply reflect the number of particles that each version of this element contains in the nucleus of its atoms. In other words, they symbolize that uranium-235 has 3 neutrons less in its nucleus than uranium-238.

Those 3 neutrons are very important, because the amount of protons and neutrons that an atom contains in its nucleus determines if that nucleus is stable or not. The unstable nuclei tend to expel the excess particles to gain stability… And those particles that are fired at high speed are what we call nuclear radiation.

There are the types of radiation that an atomic nucleus usually emits when it is unstable:

  • Alpha
  • Beta
  • Gamma

But there is another type of unstable atomic nucleus that, instead of emitting some loose particle to stabilize, split in two, producing two new distinct nuclei. This is the process that is called nuclear fission and is the one that interests us today.

These 3 neutrons make the uranium-235 unstable enough so that its nuclei tend to split in two spontaneously when absorbing a neutron, releasing a lot of energy during the process. This principle is the one that takes advantage of nuclear power plants to generate energy: neutrons are fired against the fuel and the uranium-235 atoms of the cylinders absorb and divide them, ejecting more neutrons that in turn cause the fission of other atoms and they generate even more energy.

atoms.jpg
How is it supposed to generate energy from atoms with this chain reaction?

During the nuclear fission reactions, the nuclei of uranium-235 break and the neutrons released, shake the atoms that surround them… And that increase of speed of the atoms inside the cylinders of enriched uranium results in an increase in its temperature.

The fuel of a nuclear power plant is a solid material that does not burn or produce gases, such as fossil fuels, but simply stays warm thanks to the energy released by the uranium atoms that are constantly breaking in their inside.

Only uranium-235 can be fissioned so, for the reaction to be sustained, its proportion in the fuel must increase from 0.7% found in the minerals to between 3, 5% and 5%. That is what is called enriching uranium: simply take the uranium that is already in nature and change the proportion of the isotopes it contains.

The heat released by the fuel of a nuclear reactor is used to heat the surrounding water, converting it into steam that turns the turbine that produces the electricity, as in any other type of thermal power plant. In fact, as opposite to what many people believe, the “smoke” that comes out of the chimneys of nuclear power plants is nothing more than water vapor… You do not need to worry about the possible radioactivity of that steam, because it is not the water that has been in contact with the radioactive material of the fuel, this water is in contact with the cooling circuit.

Nuclear fuel does not last forever: as the fission reactions progress inside the cylinders, the number of uranium-235 atoms remaining in the fuel elements decreases and their temperature goes down. After approximately 4.5 years of operation in which the plant produces energy 24 hours a day, uranium-235 is depleted and it is necessary to change the uranium dioxide cylinders for new fuel (specifically, the plants go through 3 cycles of 18 months and in each of them one third of the fuel elements are replaced). Used cylinders are now nuclear waste.

And these dangerous cylinders of radioactive uranium are precisely what makes people against nuclear power.

The waste derived from the production of nuclear energy have great advantages that make it possible to contain them easily.

They occupy very little space because nuclear fuel generates immense amounts of energy from a small volume of material (1 kg of enriched uranium dioxide produces as much energy as 10,000 kg of oil or 14,000 kg of coal). For example, a 1 GW nuclear reactor uses only 27 tons of fuel per year, a mass that, taking into account that the density of uranium dioxide is almost 11,000 kilos per cubic meter, occupies a volume of just over two cubic meters.

In addition, since these wastes are solid, they can be easily contained and transported to a place where they do not bother anyone, something that can not be done with the greenhouse gases or the polluting particles that the burning of fossil fuels emits.

How can they not bother anyone? What about the radiation it emits?

Nuclear radiation is nothing more than particles that come off the radioactive atoms and can harm us in two ways, depending on the amount we are exposed to:

They are capable of damaging part of the DNA of our cells when they hit them and, if the cell does not die or is able to repair it, it is possible that it begins to reproduce without control when trying to follow the orders of the damaged DNA, giving rise to a tumor.

In the most extreme cases, a very high dose of radiation can cause damage to so many cells in our body that the organs start to fail, leading to death in a few days.

Although none of these scenarios sounds nice, these harmful effects are very easy to avoid: as the particles and gamma rays have to hit our cells to be able to harm us, it is enough to place the radioactive materials behind a barrier that blocks the radiation so that it can not reach anyone.

Nuclear waste storage

This is the reason why nuclear waste is stored in underground facilities dug to a depth that varies according to its location, but is usually around 500 meters. In this way, in addition to the shield represented by the barrels in which they are encapsulated, the waste is separated from the outside world by hundreds of meters of rock that stop the radiation and prevent it from damaging any living being. Besides, they are contained within a heavy water pool that absorbs the radiation emitted.

To prevent water from dissolving the nuclear waste and radioactive material to seep through the rocks, the contents of the barrels are vitrified, so that the the residues are encapsulated in a solid block of glass that is chemically inert. And not only the used fuel is vitrified: the same is done with other materials that are contaminated during the fission operation and with the radioactive elements extracted from the reactor water.

The issue of nuclear waste management is much more complex than I can explain here, but you can find a lot of additional information through internet.

Life cycle of nuclear waste

There’s something you do not take into account: radioactive waste emits radiation for thousands of years. During that time, many things can happen even if they are underground…

For that reason the waste is stored in facilities that are in regions that are not geologically active, to minimize that risk. In this way, even if the facilities failed or were blocked by a landslide, the material would still be confined in a safe place underground, without being able to disturb anyone.

Nuclear waste is not always condemned to spend several thousand years underground: due to the radioactive decomposition of spent fuel atoms, chemical elements are constantly being synthesized inside it that are not usually found in large quantities in the nature. As a result, very useful elements can be extracted from the nuclear waste that would be very difficult to obtain in another way, such as the americium that smoke detectors carry or some radioactive isotopes that are used in medicine to treat certain types of cancer.

Of course, no source of energy can guarantee a 100% safety and there is always the remote possibility of a failure occurring. Have a look to the mortality data associated with each energy source in relation to the amount of energy it produces. And they can clearly see that nuclear energy is the safest of all.

And what about the danger of nuclear accidents, such as Chernobyl? Or Fukushima?

The message is that an accident like Chernobyl could not happen in modern nuclear power plants and the case of Fukushima was not as disastrous as all the sensationalism that emerged around it suggests. In fact, the leak from the plant did not cause a single death due to the radiation released.

When all the deaths caused by each energy sector are taken into account, nuclear energy is the one that causes fewer deaths in proportion to the amount of energy it produces.

There will be some who argue that the deaths derived from the manufacture and maintenance of each technology should not be included in this graph, but even so, the data reflect very well that, despite the trace that episodes such as Chernobyl have left in the collective imaginary, nuclear energy is a perfectly safe technology.

Conclusions

Most of the current energy demand of our planet is being covered with fossil fuels, substances that generate a lot of energy, but that are not only filling the atmosphere with huge amounts of carbon dioxide that are altering the climate of the planet , but also of polluting particles that produce respiratory diseases and kill millions of people each year. Unfortunately, renewable energies are not going to eradicate these problems because they are too inefficient and have a greater impact on the nature of what people usually think. Furthermore, if nuclear power plants continue to be closed, fossil fuels will continue to be used to provide the energy that renewables can not supply… Because, after all, if you depend on renewables, you will always need to have some means to produce energy when renewables can not do it

I believe that ideologies and politics are irrelevant in this debate. We simply can not afford to keep ignoring nuclear energy: a safe, reliable and clean technology, in addition to the only one capable of supplying the monstrous energy demand of our society and at the same time mitigate the effects of climate change.

Hope this article has been interesting for you and looking forward to your comments!

Why do We Have to Bet for Nuclear Energy
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