Lesson Video: Nuclear Power | Nagwa Lesson Video: Nuclear Power | Nagwa

Lesson Video: Nuclear Power Physics

In this lesson, we will learn how to describe the advantages and disadvantages of generating electricity from nuclear fission.

11:15

Video Transcript

In this video, our topic is nuclear power. Ever since the 1940s, when the first controlled nuclear reaction took place, the possibility of converting nuclear energy to electrical energy has existed. Today, nuclear power supplies just over 10 percent of global energy needs. In this video, we’ll look into how this process works as well as the advantages and disadvantages of nuclear energy.

A good place to start when talking about nuclear power is the nucleus of an atom. This is where all the energy in the nuclear power production process comes from. In this picture of a nucleus, we’ve drawn protons with a positive charge in blue and neutrons with no net charge in green.

Now, in order for all these protons and neutrons to stick together like they do in a nucleus, lots of energy is required. And furthermore, if we were to deliberately break apart a nucleus, say to split it into two smaller pieces, then some of that energy will be released. The name for this process, when a nucleus splits apart, is fission. And it’s fission that’s at the heart of nuclear power production.

If we think about a nuclear power plant, also called a nuclear power station, the place where fission occurs is called the reactor core. Inside this core, some specific atomic element, often uranium or plutonium, is being split apart through the process of fission into smaller elements. And when this happens, large quantities of heat energy are released.

If we were to keep track of the energy transformations that take place as nuclear energy is transformed into electrical energy. We’ve seen that at the outset, the initial energy in our system is stored in the nucleus of atoms, its nuclear energy. Then, through the process of fission, that energy becomes a thermal energy. Inside a nuclear power plant, this thermal energy is used to heat up water.

Eventually, the water boils. That is, it turns to steam. This steam then pushes on very large cylinders in the power plant, causing them to rotate. In this way, the thermal energy of the water is converted to kinetic energy of these massive rotating cylinders. And it’s these cylinders that drive the generation of electricity. This is the final form of energy produced in the plant. The electrical energy is then distributed out from the plant for use by consumers.

Now, often when we see pictures of nuclear power plants, we don’t just see the reactor core, but we often see a very tall tower position nearby. In this tower often has a white plume of gas coming from it. This tower, and sometimes there are multiple towers at a given nuclear power station, is called a cooling tower. And its purpose, ultimately, is to help remove heat that is generated inside the reactor core during the fission process. Unused heat energy is one of the byproducts of the nuclear fission process. And this brings us to the topic of the various advantages and disadvantages of nuclear power in general.

Virtually, every energy source has pros and cons to it, and nuclear power is no different. When we think about the advantages of this process, there are several we can name. One is that the cost of fuel in this case, reactor grade uranium or plutonium, is low compared to other power plant fuel sources like coal or gas. Another advantage of nuclear power is that nuclear power plants, once they’re up and running, can have a long lifetime. A plant can continue in operation for upwards of 40 years.

And another advantage of nuclear power is that this process emits no greenhouse gases. In particular, no carbon dioxide is released. This means that while the nuclear power plant is in operation, it does not contribute to the trapping of heat within Earth’s atmosphere. It doesn’t give off any pollution that would do that.

On the disadvantages side of things, perhaps the number one disadvantage of nuclear power plants is that they produce radioactive waste. This gets back to the process of fission that we talked about earlier. After fission has occurred, the resulting elements themselves can decay further into other atomic nuclei. As part of this decay, radiation is emitted from these nuclei. And that radiation is high energy enough to be dangerous to humans and other forms of life.

So, once the original fuel in our fission process is used up, we have leftovers that themselves are dangerous and need to be shielded and disposed of carefully. This radioactive waste can be dangerous for a fairly long time, hundreds or thousands of years. So, safely and responsibly dealing with radioactive waste is one of the great challenges and one of the disadvantages of nuclear power production.

Another common disadvantage of nuclear power is thermal water pollution. The idea here is that some of the water that’s used to cool off a nuclear reactor, after it’s gotten so hot through the fission process, is then sent back into the environment, be it a lake or a river where the water came from. But in the process of circulating through the power plant to cool off the core, the water was heated up. This means when it returns to its source, it will be warmer than the source naturally is.

Increasing the water temperature of a lake or a pond, even a small amount, can have a significant effect on the plant and wildlife there. Partly because of all the safety challenges involved in producing nuclear power, these power stations are expensive to build. It may take 20 to 30 years to plan and completely build out a nuclear power plant. All that said, let’s now get some practice with these ideas.

Fill in the blanks. A nuclear power station converts blank energy into blank energy.

Okay, so in this question, we wanna figure out what words go in each blank. And to do this, we’ll want to understand the energy conversion process that goes on in a nuclear power station. We can recall that, true to its name, nuclear power begins with energy that’s stored in the nucleus of atoms.

Say that we have a large atomic nucleus made up of protons in blue and neutrons in green. The fact that all these masses are so densely packed and bound together tells us that the nucleus has lots of energy. And if it were to split apart, in a process known as fission, then some of this energy would be released. This is exactly what takes place in a nuclear power station. Atomic nuclei are split apart to release energy. So, this tells us what kind of energy a nuclear power station starts out with.

What word goes in our first blank? Since the energy that these power stations begin with is stored in the nuclei of atoms, that means it’s nuclear energy. And when fission occurs, some of this energy is released from the process as heat. In the context of a nuclear power station, this heat energy is used to heat up water. Eventually, the water boils, becomes steam. And this steam, which is at high pressure, pushes against gigantic cylinders causing them to rotate.

It’s the rotation of these gigantic cylinders that generates electrical energy. We could say then that the nuclear energy in the atoms involved is converted to thermal energy. And then, that heat energy, stored in the steam, is converted to kinetic energy as it causes the cylinders to turn. And those rotating cylinders power the generation of the final form of energy the power station produces, electrical energy. Now that the blanks are filled in, our sentence reads, a nuclear power station converts nuclear energy into electrical energy.

Let’s take a look now at a second example exercise.

Which of the following correctly describes how energy is released from uranium in nuclear reactors? A) Uranium nuclei radiate gamma rays, which are absorbed by the material around the uranium in the core of the reactor, heating it up. B) Uranium nuclei radiate microwave radiation, which is absorbed by the material around the uranium in the core of the reactor, heating it up. Option C, the nuclei of uranium atoms split, releasing energy stored within the nucleus and causing the uranium and the material around it in the core of the reactor to heat up. Lastly, option D, uranium nuclei emit electrons, which are used directly to generate electricity.

So, what we want to do in this exercise is figure out which of these four options correctly describes how energy is released from uranium in a nuclear reactor. If we think about such a reactor, we realise that uranium is the fuel that powers the whole process. And we can recall that the way that energy is released from uranium, or whatever the radioactive element is in the nuclear reactor, is through a process called fission.

Fission involves the splitting of a larger atomic nucleus into two or more smaller ones. When it goes through fission, uranium not only splits into smaller atomic elements, but it also releases energy. And it’s that energy, in a nuclear reactor, that powers the whole electricity generation process.

Now, as we review our four answer options, we see that they divide up generally into two types of answers. Option A says that uranium nuclei radiate gamma rays. Option B says that these nuclei radiate microwaves. Option C says that these uranium atoms split. And option D says that the nuclei emit electrons. So, the first type of the two kinds of answers we’re seeing here involves uranium nuclei emitting something, some particle or some amount of energy. In option A, that’s gamma rays. In option B, it’s microwaves. And in option D, it’s electrons. So, that’s our first answer type, where the uranium nuclei emits something.

We can see, though, that option C offers a different kind of answer. Option C describes a process where instead of the uranium atoms emitting some radiation, instead they split apart, physically breaking into smaller pieces. And this splitting apart is a good description of what the word fission means. And because fission is the process by which energy is released from uranium in a nuclear reactor, that means we do want this description of atoms splitting to be in our answer. That’s a correct representation of what fission means.

Because options A, B, and D don’t involve any mention of atomic splitting or fission, we’ll cross them off the list. Option C, though, clearly indicates the fission process taking place. And indeed, in a nuclear reactor, that’s the true process by which energy is released from uranium. Option C goes on to say that as a result of this split, energy is released that causes the uranium and the material around it in the core of the reactor to heat up. This then is our answer for how energy is released from uranium in nuclear reactors.

Let’s summarise now what we’ve learned about nuclear power. First off, we saw that nuclear power involves converting the energy stored in atomic nuclei to electrical energy. This energy conversion happens thanks to a process called fission, where a large nucleus is split into two or more smaller nuclei, which releases energy. In a nuclear power station, the energy, that’s initially stored in the nuclei of the fissionable material, is converted to thermal or heat energy. Which is then converted into kinetic energy as gigantic turbines spin. Which finally is turned into electrical energy, the output energy form of the power plant.

And finally, we looked at advantages and disadvantages to nuclear power. Advantages included low fuel costs, a long lifetime of a nuclear power facility, and no greenhouse gas emission while the plant is in operation. Disadvantages of nuclear power facilities include the production of radioactive waste, the likelihood of thermal water pollution, and the fact that these plants and stations are expensive to build. Keeping all this in mind, this has been an overview of nuclear power.

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