Introduction to Radiation

Part of the CNSC’s mandate is to disseminate objective scientific, technical and regulatory information to the public.

The purpose of this section is to provide clear and factual information about radiation – the types of radiation that exist, its sources, uses, and the rules in place to protect Canadians, and people who work in or live near nuclear facilities.

In this section you will find:

Download Introduction to Radiation (PDF)

Video: Radiation and Health

The CNSC continues to explain radiation in simpler terms. The Radiation and Health video takes you beyond the tiny world of the atom to explore sources of radiation, the concept of dose, and how radiation affects the body and health.

Transcript

(The CNSC logo forms directly on the screen. After a moment, the title card fades in below the logo, followed by text on screen beneath it.)

Text on Screen:          Radiation and Health
Understanding radiation with the Canadian Nuclear Safety Commission

We live on a planet full of natural radiation. It’s present in soil, rocks, the air we breathe, the water we drink, and even in our own bodies. This natural radiation makes up the bulk of the total radiation we are exposed to every day.

(The CNSC logo and text-on-screen both fade out. Our host, Julie Burtt fades in. In a long shot we see Julie with the earth spinning in her hand, she tosses it up in the air and it fills the screen. White text bubbles with the words: soil, rocks, air and water pop up out of the earth as they are mentioned.)

We’re also exposed to artificial radiation, including medical tests like x-rays, and small amounts of radioactive material – called “radionuclides” – released from licensed nuclear facilities.

(Cut to a long shot of Julie as graphics of an x-ray and reactor icon appear on the right side of her. The camera slowly zooms from a long shot to a medium long shot. Throughout the entire video, Julie addresses the camera directly.)

I’m Julie and I work for the Canadian Nuclear Safety Commission.

Text on Screen:          Julie Burtt
                                    Radiation and Health Sciences Officer
                                    Canadian Nuclear Safety Commission

(Cut to a medium close up of Julie, a vertical line appears in the centre of the screen beneath Julie, then simultaneously expands outwards to both the left and right to spell out her name and title.)

We can’t see, hear, smell, touch or taste radiation. Until 1895 we didn’t even know it existed! But we’ve come a long way in our understanding about what ionizing radiation is and how it affects our bodies and our environment.

(Julie’s name/title super disappears. Cut to a long shot of Julie as she addresses the camera directly.)

For example, we can measure the amount of radiation in the environment with radiation detection devices – like Geiger counters. They count the energy deposited in the detector by the radiation.

 (Cut to a medium close-up shot of Julie. Julie continues as a voiceover as we see a montage of images, including an inspector with a radiation detection device, a Geiger counter, and another inspector at work with a device.)

Listen to the sound of naturally uranium in this rock sample. That count can then be used to calculate a dose.

(Cut to a medium close-up of Julie. Julie shows a Geiger counter, she then demonstrates slow clicks and fast clicks with a rock sample.)

A dose is the quantity we use when we talk about the potential health effects of radiation. A dose takes into account the type of radiation you’ve been exposed to and the organs in your body, which have been exposed.

Text on Screen:          Dose

  • Type of radiation
  • Organs exposed

(Cut to a long shot of Julie. The words “dose,” “type of radiation,” and “organs exposed,” appear to the left of Julie.)

It is expressed using the unit “sievert” or more commonly “millisievert” which is a 1,000 times smaller.

Text on Screen:          (Sv) sievert
(mSv) millisievert

(Cut to a medium shot of Julie, from the right she brings in the word “(Sv) sievert,” which then transitions into the word “(mSv) millisievert.”)

On average, Canadians receive a dose of 1.8 mSv every year from natural background radiation coming from radioactive materials found in soil, rocks, some foods and cosmic radiation. This number can range from 1 to 4 mSv depending on where you live in Canada. For example, the cosmic radiation is more intense for people living at higher altitudes or further from the equator. Likewise, terrestrial radiation is higher for people living in areas where rocks and soil contain more natural radioactive elements.

Text on Screen:          Natural Background 1.8 mSv
Yellowknife: 3.1 mSv
Vancouver: 1.3 mSv
Regina: 3.5 mSv
Winnipeg: 4.1 mSv
Toronto: 1.6 mSv
Montreal: 1.6 mSv

(Cut to long shot of Julie, an animated map of Canada replaces Julie as she continues as voiceover. To the left of the map, the text “Natural Background 1.8 mSv” appears. White text bubbles appear across the map highlighting the locations natural background radiation dose. The following text appears, “Yellowknife: 3.1 mSv, Vancouver: 1.3 mSv, Regina: 3.5 mSv, Winnipeg: 4.1 mSv, Toronto: 1.6 mSv, Montreal: 1.6 mSv, Halifax: 2.5 mSv, St-John’s: 1.6 mSv.”)

So what are the health effects caused by radiation? Certain types of radiation have enough energy to penetrate our bodies. When it passes through tissues in the body, electrically charged atoms, called ions, can change or destroy cells. The body is a pretty amazing organism and most of the time, these cells repair themselves. This can happen millions of times every day!

(Cut to long shot of Julie. Julie continues as voiceover as animated graphic of a human body appears. We zoom into the body and view an animation of radiation penetrating the body; we see cells being damaged as cells turn from blue to red. Animation shows cells repairing themselves.)

If however the DNA or other critical parts of the cell receive a large dose of radiation all at once, the cell may die or be damaged beyond repair. If this happens to a large number of cells, “tissue effects” can occur. Examples of these effects include cataracts, which can happen at around 500 mSv, and acute radiation syndrome symptoms like nausea and skin burns that can be seen at doses well over 1,000 mSv.

Text on Screen:          Tissue Effects
                                    Cataracts 500 mSv
                                    Nausea + Skin Burns 1000 mSv

(Zoom in closer to cells. Animate more radiation penetrating into the body and cells being damaged, black spots appear on cell. The text “Tissue Effects, Cataracts 500 mSv, Nausea + Skin Burns 1000 mSv” appear to the left of the cell animation.)

Extremely high levels of radiation in the range of 4,000 to 5,000 mSv can be fatal. This level of exposure is very rare. 

(Cut to long shot of Julie.)

If the cell incorrectly repairs itself, but continues to live, then “stochastic effects” could occur. This type of damage could develop into cancer over time.

Text on Screen:          Stochastic Effects

(Cut to animation of cells, a series of blue and red cells are seen in the body. The text, “Stochastic effects” appears on the left side of the screen. More of the blue cells turn red.)

The higher the radiation dose, the more likely a cancer will occur. In population studies, we generally don’t observe health effects appearing at doses lower than about 100 mSv.

(Cut to long shot of Julie.)

Most importantly, our understanding of how cells can be damaged by radiation allows us to use that same knowledge to target and kill cancer cells.

(Cut back to animation of cells. The section of red cells slowly turn black. Animation of radiation penetrating the body, black cells are dissolved by the radiation.)

We know what happens once radiation enters the body, but how does it get inside you in the first place?

(Cut to long shot of Julie.)

When we talk about radiation exposure, we are talking about “pathways”; there are various pathways radiation can take to get inside the body —including the air we breathe and the food we eat—all of which contribute to our radiation dose.

Text on Screen:          Pathways

(Cut to medium close-up of Julie. Julie pulls one super from the left that says, “pathways.”)

Did you know a brazil nut naturally contains trace amounts of the radionuclides potassium-40 and radium-226? Delicious!

(Cut to long shot of Julie and then to a close-up of Julie’s hand holding a brazil nut. Cut to long shot of Julie holding brazil nut, Julie then eats brazil nut.)

Our bodies can’t distinguish between natural and artificial radionuclides. One source of artificial radiation is the small, controlled quantity of radionuclides permitted to be released from licensed nuclear facilities into the environment.

(Cut to medium close-up of Julie.)

These radionuclides could be carried in the air and deposited in a farmer’s field. Animals eat grass and grains from that field and then provide food that people eat and drink. Understanding that chain of events – that one pathway - makes it possible to begin estimating a dose to the person who consumes that food.

(Cut to long shot of Julie. On the left side of screen the following graphics appear: sky with fluffy clouds, farmer’s field, cow and pig, and steak, milk and grain. A white line connects each circular graphic.

Overall, the amount of radionuclides in foods is extremely small and does not affect your health.

(Cut to medium close-up of Julie.)

For major facilities, a similar assessment is done to look at the impact of radiation on the environment itself, including wildlife and vegetation.  

(Cut to long shot of Julie. Julie is panned to the right. Graphics appear in the left side of the frame of trees, and a deer, rabbit and fish. The graphic of the tree appears in the centre, as the graphics of the animals are connected by white lines to the tree graphic.)

Since radiation has the potential to cause harm, it must be strictly regulated. That’s where the Canadian Nuclear Safety Commission comes in; our mandate is to regulate the use of nuclear energy and materials to protect health, safety, security and the environment. The Radiation Protection Regulations define the dose limits used to protect the health of the public and nuclear energy workers.

Text on Screen:          Radiation Protection Regulations

(Cut to medium close-up of Julie. The CNSC logo appears to the left of Julie. Julie pulls up a super from the bottom of the screen with the text, “Radiation Protection Regulations.”)

Members of the public are limited to 1 mSv of exposure per year from licensed activities; this is in addition to all other sources of radiation, like natural or medically related radiation. Workers are limited to 50 mSv in one year and 100 mSv over 5 years.

(Cut to a long shot of Julie. Julie continues as voiceover as we see footage of public crowd, which swipes to a hiker walking through a forest, then to a healthcare worker administrating a needle to a patient, and finally workers in a lab.)

Nuclear energy workers can wear small devices called “dosimeters” that measure and track their radiation doses. This is one way to make sure they don’t exceed these limits. These dosimeters can be worn on different parts of the body depending on the kind of work they do.

(Cut to a long shot of Julie. Cut to close-up of Julie holding up dosimeter. Cut to long shot of Julie, then to medium close-up as Julie takes the lapel on her jacket with her hand, then to close-up of Julie holding the dosimeter to her then clipping on her jacket. Cut to medium close-up of Julie putting on ring. Cut to close-up of ring on Julie’s hand.)

It’s important to note that these dose limits are regulatory limits, and not health limits. As a result of our strict regulations and oversight, we are happy to report that these dose limits are rarely reached.

(Cut to a medium close-up of Julie, and then to a long shot.)

I’ve given you a lot of information. Let’s put some of the numbers in perspective.

(Cut to a medium close-up of Julie.)

Text on Screen:          0.001 mSv
                                    0.1 mSv

Members of the public living near a major facility typically receive 0.001 mSv a year from licensed nuclear activities, which is less than the 0.1 mSv of a typical chest x-ray.

(Cut to a long shot of Julie as she stands in the right side of the frame. A graph of virtual green block tower begins to be built to her left, starting with a tiny sliver to represent “0.001 mSv” and “0.1 mSv.” Cut to close-up of virtual blocks.)

Text on Screen:          0.001 mSv
                                    0.1 mSv
1 mSv
1.8 mSv

The public dose limit is 1 mSv per year. This is on top of the dose received through natural background radiation which in Canada is nearly twice that high, at an annual average of 1.8 mSv.

(Close-up of virtual blocks remains, an additional block is added of “1 mSv.” An animated “1.8 mSv” lighter green block is also added to the graphic).

Text on Screen:          0.001 mSv
                                    0.1 mSv
1 mSv
1.8 mSv
                                    50 mSv
                                    100 mSv
                                    500 mSv
                                    1000 mSv

Workers are limited to 50 mSv in one year and 100 mSv in 5 years. In fact they typically get far smaller doses. Health effects like cataracts can happen at 500 mSv and acute radiation syndrome symptoms can be seen at doses well over 1,000 mSv.

(Cut to long shot of Julie standing beside block graph tower, an additional “50 mSv” block is added, a “100 mSv” block, a “500 mSv” block, and finally a “1000 mSv” block.)

I know radiation doses can sound scary, but you can rest assured; the Canadian Nuclear Safety Commission is there, overseeing the nuclear sector to protect your health and safety, as well as that of the environment.

(Cut to medium close-up of Julie. The CNSC logo appears in her palm in the left frame.

Text on Screen:          Canadian Nuclear Safety Commission
                                    Nuclearsafety.gc.ca

The Canadian Nuclear Safety Commission: the answers you need, from a source you can trust! Visit our website, Facebook page or YouTube channel.

(Fade out Julie and CROSSFADE IN full-screen of the CNSC name, logo, url, Canada Wordmark, YouTube/Facebook icons.)

Video: What is Radiation?

Transcript

Title: What is Radiation?

(The CNSC logo forms directly on the screen. After a moment, the title card fades in below the logo, followed by text on screen beneath it.)

Text on screen: What is radiation?

Text on screen: Understanding radiation with the Canadian Nuclear Safety Commission

What do smoke detectors, emergency lights and nuclear power all have in common? Radiation! But what exactly is radiation?

(The SFX and text-on-screen both fade out. Our host, Julie Burtt fades in, above her graphics of a smoke detector, exit sign and nuclear power appear one at a time. The camera slowly zooms from a long shot to a medium long shot. Throughout the entire video, Julie addresses the camera directly.)

Thanks to high-school science class, most of us have heard about radiation. But many of us may not know exactly what it is.

(Graphics disappear, and cut to a medium long shot of Julie.)

I’m Julie, and I work for the Canadian Nuclear Safety Commission.

(Cut to a medium close up of Julie, a vertical line appears in the centre of the screen beneath Julie, then simultaneously expands outwards to both the left and right, like an atom splitting, to spell out her name and title.)

Text on screen:           Julie Burtt
Radiation and Health Sciences Officer
Canadian Nuclear Safety Commission

Simply put, radiation is the release of energy in the form of moving waves or streams of particles. This energy can be low-level, like microwaves and cell phones; or high-level, like X-rays or cosmic rays from outer space. These are known as non-ionizing and ionizing radiation.

(Julie’s name/title super disappears. Cut to a medium long shot as Julie gives examples of non-ionizing and ionizing radiation applications, visuals illustrating each of the examples she gives “appear” on the screen above her: a microwave, cell phone, x-rays, and cosmic rays. As well, the words “non-ionizing” and “ionizing” appear to the left and right of her as text-on-screen).

Text on screen:           non-ionizing
ionizing

But if we really want to understand radiation, we need to go inside the tiny world of the atom.

(Cut to a medium close-up, Julie glances at an animated atom spinning above her hand. Julie playfully “tosses” the atom towards the camera.)

Remember that high-school science class? Atoms are the microscopic building blocks of all matter in the universe.

(As the atom “hits” the camera, filling the frame, we cut to a full animation of an atom, with animated electrons spinning around it.)

Everything around us is made up of atoms, from the largest galaxies to our own bodies.

(Shot of galaxies, which fades to an image of sunlit silhouettes.)

The centre of the atom is called the “nucleus.” That’s where the word “nuclear” comes from – there is a tremendous amount of energy inside!

(Cut to a medium close-up of Julie pulls one super from the left that says, “nucleus” and another from the right of the screen that says, “nuclear”.)

Text on screen:           Nucleus
Nuclear          

The nucleus of an atom is made up of two particles: protons, which carry a positive charge, and neutrons, which have no charge.

(Animation of an atom, text on screen highlights where the neutrons and protons are. The neutrons are illustrated as blue balls that have a negative sign on them, and the protons are seen as red balls with a positive sign.)

Text on screen:           Nucleus
Neutron
Proton

Outside the nucleus are electrons, which carry a negative charge. The attraction of these negative electrons to the positive nucleus is what keeps the atom together.

(Animation of electrons spinning around an atom on the left side of the frame, with text appearing on the right side of the frame that says, “electrons are negatively charged”.)

Text on screen: Electrons are negatively charged

Now, every element in the periodic table has a specific number of protons and neutrons.

(Fade to an image of the periodic table.)

But sometimes an atom will have too many or too few neutrons.

(Cut to animation of one atom containing protons & neutrons, which then transitions to 3 atoms.)

Text on screen:           8 protons         8 protons         8 protons
6 neutrons       8 neutrons       9 neutrons

When this happens, it becomes unstable, or “radioactive.”

(Cut to a medium close-up of Julie, who then pulls down a “radioactive” super.)

Text on screen:           radioactive

An unstable atom is called a radioisotope. For example, two extra neutrons in a hydrogen atom creates the radioisotope tritium.

(Cut back to animation of 3 atoms containing protons & neutrons. Then cut to animation of atom with two extra neutrons demonstrating that radioisotope of hydrogen is tritium.)

Text on screen:           Radioisotope of Hydrogen
Tritium

That’s the stuff that helps make exit lights glow in the dark!

(Cut to a medium close-up of Julie in left side of frame. Exit sign appears to her right, then disappears on screen.)

Radioactive atoms want to become stable again. So they release energy until they get back to a balanced state. This process is known as “radioactive decay” and there are three main types:

(Cut to a long shot of Julie, and then to a medium close up of Julie as she pulls up a super that says, “radioactive decay”.)

Text on screen: radioactive decay

Alpha, beta and gamma. Alpha particles are heavy and travel small distances; beta particles are lighter and travel further, and gamma radiation is actually a wave and it travels the farthest of all.

(Cut to animation of alpha, beta and gamma particle. A short line appears below the alpha particle, a longer line appears the beta particle, and a long wavy line appears below the gamma ray.)

Text on screen:           Alpha
Beta
gamma

The time it takes for half of the radioactive atoms of a radioisotope to decay is called a “half-life”. Half-lives can range from a fraction of a second, to billions of years.

(Cut to a medium close up of Julie as she pulls up a super from the right with the words, “half-life”.)

Text on screen:           half-life

Let me give you an example of how half-lives come into play in nuclear medicine.

(Cut to a medium long shot of Julie.)

Doctors inject patients with the radioisotope Technetium-99m which emits gamma radiation. A gamma camera can then take pictures of the patient’s insides to help with the diagnosis. The relatively short half-life of 6 hours for this radioisotope makes it ideal for these types of tests.

(Cut to visuals that illustrate Doctor injecting patient, and then to a shot of a Doctor using a gamma camera on a patient, and then back to a medium close-up of Julie addressing the camera.)

Let’s pretend these jellybeans are the nuclei of Tc-99m. After one half-life, half the atoms still in the body remain unstable, or “radioactive”.

(Cut to a medium shot of Julie standing in front of a table covered in jellybeans. A long, old-fashioned ruler is in Julie’s hands. Julie places the ruler down on the table in the middle of the pile of jellybeans, and wipes half the jellybeans off the table.)

After two half-lives, one quarter of the atoms remain radioactive.

(Cut to a medium close-up of Julie as she speaks, and then to a medium shot as Julie places the ruler down again and wipes half the remaining jellybeans off the table.)

After three half-lives… well, you get the idea.

(From a medium shot, Julie continues to wipe off the remaining jellybeans in fast motion, until there is one left.)

After 24 hours, almost all the radioactivity is gone, thanks to radioactive decay and the body’s natural… shall we say…“processing.”

(Cut to close-up of Julie’s hand holding remaining jelly bean, and then cut to medium close-up of Julie speaking directly to the camera. Julie pops the jelly bean in her mouth. SFX of a toilet flushing, Julie reacts, amused then smiles back at the camera.)

And that ends our science class on radiation. Congratulations – you passed!

(Cut back to a medium long shot of Julie facing camera.)

Now for the bonus question: can you tell me who keeps an eye on the nuclear sector in Canada? That would be us, the Canadian Nuclear Safety Commission!

(Cut to a medium close-up of Julie who reaches up out of frame and “pulls down” a super with the CNSC logo and title.)

We regulate the use of nuclear substances and materials, and ensure that all nuclear materials are used for peaceful purposes. We also work to protect your health and safety, as well as that of the environment.

(Cut to montage of images of the CNSC at work and those it helps, shots of work environments that use nuclear substances, and shots of a woman working in the environment with technical equipment.)

The Canadian Nuclear Safety Commission: the answers you need, from a source you can trust! Visit us at nuclearsafety.gc.ca, on Youtube or Facebook.

(Cut back to a medium long shot of Julie, and then to a medium close-up of Julie as she reaches down out of frame and “pulls up” a super with the CNSC url. Fade out Julie and CROSSFADE IN full-screen of the CNSC name, logo, url, Canada Wordmark, Youtube/Facebook icons.)

Text on screen:           We will never compromise safety.

The CNSC demystifies radiation – we answer the question What Is Radiation? The video features CNSC experts explaining the basics of radiation in simple terms – what it is, the different types, radioisotopes, and radioactive decay.