Video Transcript
In this video, we’re going to learn
about the applications of radioactivity. Although radioactive materials are
often dangerous, we’ll see that they also have lots of useful applications. These include agriculture,
medicine, power generation, industry, and even space exploration. Before we look at these
applications in more detail, let’s start with a reminder of what radioactivity
is.
This is an atom. It consists of a nucleus, that’s
this part here, surrounded by a number of electrons. Now, in some atoms, the nucleus is
unstable, and when a nucleus is unstable, it can sometimes spontaneously change into
a more stable form. This process of spontaneous change
is called nuclear decay, and when a nucleus undergoes nuclear decay, it can emit
particles and waves, which we call nuclear radiation. So nuclear radiation is emitted by
unstable atomic nuclei when they undergo nuclear decay.
If a material contains unstable
nuclei, we say that that material is radioactive. The radiation given off by
radioactive materials transfers energy from its nuclei to its surroundings, and this
energy makes nuclear radiation really useful. Perhaps the most obvious
application of radioactivity is in nuclear power plants. Nuclear power plants use rods of
highly radioactive material, such as uranium, as fuel. Because these materials are so
radioactive, they transfer a lot of energy to their surroundings in a short
time. In nuclear power plants, the energy
released by the radioactive fuel is used to heat water. This causes the water to boil and
turn into steam. This steam can then be used to turn
a turbine, and this motion can then be used to generate electricity.
Throughout this process, nuclear
energy in the fuel is transferred into thermal energy, which is ultimately
transferred into electrical energy. It’s important to note that nuclear
power plants produce radioactive waste. Over time, the rate at which
nuclear fuel gives off energy decreases. And after a while, it no longer
gives off enough energy to be useful for generating electricity. At this point, we can say that the
nuclear fuel has decayed into nuclear waste. And once it reaches the state, it
can be disposed of.
As well as generating electricity,
radioactivity has applications in medicine, for example, in medical imaging. Special radioactive substances
known as tracers can help us create images of the inside of the body. When a tracer is injected into the
body, it gets naturally absorbed by a specific body parts, with different traces
being absorbed by different parts of the body. Special equipment can then be used
to monitor the radiation given off by the tracer once it’s being absorbed by a
specific body part. And this enables a detailed picture
to be built up of the body part in question.
Radioactivity can also be used for
cancer treatment. Nuclear radiation can damage
cells. So by carefully focusing radiation
on specific areas in the body, it can be used to destroy cancer cells without
damaging too many healthy body cells. This type of treatment is called
radiotherapy.
The next application area we’ll
look at is agriculture. Agriculture refers to the
cultivation of plants and livestock for food and other uses. Insects are a big problem in
agriculture. As well as damaging crops, they can
spread diseases to livestock, lay their eggs in grain stockpiles, and generally
cause problems for farmers. However, radiation can be used to
kill or sterilize insects, controlling their population and protecting crops and
livestock.
Radioactivity can also be used to
change the properties of crops. This is done by exposing the seeds
of crops to nuclear radiation. And this can cause changes to the
DNA inside the seeds. These changes are called mutations,
and they can change the way in which the seed grows, sometimes in a good way. And when good mutations occur, then
farmers can grow the seeds from these mutated plants and pass their properties on to
the next generation of crops.
Radioactivity also has many
applications in industry. For example, it can be used to
detect manufacturing defects in products such as this car door. This is done by placing of
radioactive source on one side of the product and a sensitive radiation detector on
the other side. Nuclear radiation which passes
through the product is picked up by the detector, enabling images to be created of
the inside of the product. This can show up welding defects
and other flaws that may have occurred during manufacturing. Some industrial processes need very
high temperatures in order to produce materials or products, and radioactive
materials can be used to generate these high temperatures as radiation transfers
nuclear energy into thermal energy.
The next application of
radioactivity is in mining. Underground deposits of oil and gas
are often mined so they can be used as fuel. Finding these deposits can often be
difficult. However, radioactivity gives us a
way of locating. The underground rocks that contain
oil and gas deposits also contain radioactive elements. So by detecting the radiation given
off by these rocks, radiation detectors can be used to detect oil and gas
deposits.
The final application of
radioactivity that we’re going to look at is in spacecraft. Radioactive materials can be used
to generate the electricity used by spacecraft such as unmanned space probes. Spacecraft such as these use
nuclear batteries. Nuclear batteries contain
radioactive material. The nuclear radiation given off by
this material transfers energy from its atomic nuclei to thermal energy, which is
then used to generate electricity. So in terms of the energy transfers
involved, nuclear batteries serve a similar purpose to nuclear power plants.
However, nuclear batteries use a
very different mechanism to produce electricity. They don’t heat water into steam
like a nuclear power plant does, and they also don’t contain any moving parts. Nuclear batteries are much less
powerful than nuclear power plants, but they still provide much more energy than
normal batteries, and they’re also very reliable. Okay, now that we’ve looked at some
of the main applications of radioactivity, let’s have a go at some practice
questions.
Which of the following statements
correctly describes how the emission of nuclear radiation by decaying atomic nuclei
can be used in electricity generation? (A) The energy of the particles and
waves emitted as nuclear radiation can be transferred to thermal energy. Or (B) batteries that transfer the
chemical energy of the emitted nuclear radiation to electrical energy can be
made.
Let’s start by recalling that
unstable atomic nuclei can sometimes undergo spontaneous changes known as nuclear
decay. And when atomic nuclei decay, they
emit particles and waves known as nuclear radiation. Materials which contain unstable
nuclei are known as radioactive. And electricity generation is one
of the main applications of radioactive materials. This question gives us two
statements about how radioactive materials are used to generate electricity.
Now there are two main ways in
which we can produce electricity using radioactive materials. The first is in nuclear power
plants. In nuclear power plants, the energy
of the nuclear radiation given off by radioactive materials is used to boil
water. This process transfers energy from
nuclear energy in the nuclei of atoms to thermal energy in the water. This causes the water to boil,
turning it into steam, and the steam can then be used to turn turbines, which
generate electricity.
The other method of using
radioactivity to produce electricity is in nuclear batteries. Nuclear batteries contain small
amounts of radioactive material. And the radiation given off by this
material converts nuclear energy into thermal energy, which is then used to generate
electricity. Nuclear batteries are different to
nuclear power stations in that they don’t use water and they don’t have any moving
parts. However, both nuclear batteries and
nuclear power plants involve the transfer of nuclear energy to thermal energy via
nuclear radiation. This means that statement (A) is
correct. In both nuclear power plants and
nuclear batteries, the energy of the particles and waves emitted as nuclear
radiation is transferred to thermal energy which is then used to generate
electricity.
But what about statement (B)? After all, we know that nuclear
batteries use radiation to produce electricity. There’s actually just one word in
this statement that makes it incorrect: chemical. Statement (B) says that we can make
batteries which transfer the chemical energy of nuclear radiation to electrical
energy, but this is incorrect since nuclear radiation does not have chemical
energy. So we know that statement (B) is
incorrect. And the correct answer is statement
(A).
With that answered, let’s look at
one more question.
Which of the following are current
industrial uses of nuclear radiation? (A) Producing high temperatures,
(B) making materials stronger, (C) finding defects in products, (D) forming very
small objects from blocks of raw material.
Nuclear radiation, which is emitted
by radioactive materials, has many industrial applications. These are applications where it’s
used to develop or make products and materials. Let’s take a look at each of these
possible answers in turn.
The first suggested industrial use
for radiation is in producing high temperatures. We can recall that nuclear
radiation transfers energy from the atomic nuclei of radioactive materials to their
surroundings. We usually find that this energy is
transferred to thermal energy in the surrounding environment. In other words, nuclear radiation
can heat things up. For industrial processes that
require high temperatures, radioactive materials are sometimes a good way of
producing these high temperatures. So option (A) is a current
industrial use of nuclear radiation.
Option (B) suggests that radiation
can be used to make materials stronger. Now the energy carried by nuclear
radiation means that it can change the structure of materials. However, we usually find that
nuclear radiation damages or weakens materials. It’s not used to make materials
stronger. Option (C) is finding defects in
products. Certain types of radiation can pass
through materials. So by directing radiation so that
it passes through manufactured products and using a detector to pick up the
radiation that emerges from the other side, images can be built up which show
internal defects in the products, which would otherwise be invisible. So option (C) is another current
industrial use of radiation.
Option (D) suggests that radiation
can be used to form very small objects from blocks of raw material. Now, as we said, nuclear radiation
can sometimes change the structures of materials. However, this can’t really be
controlled. And forming very small objects from
blocks of raw material is not a current industrial application of nuclear
radiation.
With that question answered, let’s
now summarize the key points that we’ve looked at in this video. Firstly, we’ve seen that
radioactive materials contain unstable atomic nuclei which emit waves and particles
known as nuclear radiation. This radiation has many uses,
including generating electricity in nuclear power plants, medical uses such as
diagnosing and treating illnesses, agricultural uses such as killing insects and
producing useful mutations in crops, industrial uses such as finding defects in
products and producing high temperatures, uses in mining such as locating
underground oil and gas deposits, and generating electricity in spacecraft within
nuclear batteries.
