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.