WINTER 2022
The "COLD" Issue
Hello Kids! We know that there are many fun activities to take part in during the winter months such as sliding, skiing, and skating, but if you need a break from the snow and cold, why not escape to a homemade fort in your home or cuddle up on the couch with a warm blanket and read through our latest issue of Kids CONTACT. Given that it is winter, we decided to make this issue our COLD issue and demonstrate how we apply cold temperatures towards the research that we do. In this issue, you will learn about the impacts of cold on concrete, hot and cold temperatures in fusion, and how to put a 'blanket' on a building! As always, we would love to hear from you, our readers, and we enjoy your artwork and puzzles. You can always send your questions or creative projects to communications@cnl.ca. Jennifer Gardner, Editor communications@cnl.ca
What did Jack Frost say to Frosty the Snowman? Have an ICE day!
Putting a ‘blanket’ on a building Blankets are great to bundle up with when feeling cold. We even use “blankets” at the Chalk River site on the outside of some of our older buildings to keep the wood warm and dry. Some of the older buildings have old tiles on the outside that protect the buildings from the weather like winter snow storms. Before we demolish the old buildings, we need to remove these tiles in order to keep the environment safe from debris once we start to use big machines like excavators to bring them down. When the tiles are removed, the wood behind it is no longer protected from the weather. So to protect the building from the weather, and help the inside of the building stay a little warmer and drier, we carefully wrap a thin Tyvek “blanket” on the wood all around the building. Tyvek is so strong that ice or snow cannot break it down, keeping the wood warm and dry. The material is so tough that it even stays glued to the wood when the buildings are being demolished!
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Fusion fuel: From -240˚ C to +200 million˚ C Nuclear fusion. It’s the energy that powers the sun. When two hydrogen atoms are fused together, energy, in the form of heat and light is released. Scientists have been studying how to create nuclear fusion on earth for decades. It’s a big challenge because fusion reactions only happen at extremely high temperatures and pressure like in the sun. But, before we can get really, really hot fusion, we need really, really cold science. Two hydrogen isotopes – deuterium and tritium can be used as fuel for fusion reactors. CNL is able to separate these rare hydrogen isotopes. We’re also supporting other companies that are designing and building their own fuel systems for their nuclear fusion reactors. So how does this separation process work for nuclear fusion experiments?
First, hydrogen gas is cooled to -250˚C; that is so cold that the hydrogen gas becomes a liquid. Then, that liquid is placed into a tall column. The temperature of that column is very carefully controlled, and as it warms up, the different isotopes will begin to separate at different temperatures. Each isotope has a very slightly different boiling point: tritium turns to a gas at -248˚C, deuterium at -249˚C, and hydrogen (protium) at -252˚C. Because of this, we can capture the isotopes as a gas as they begin to boil when the liquid warms up. Once the isotopes are separated, the deuterium and tritium are ready to be used in nuclear fusion reactors to recreate that same “star power” here on earth.
To make fusion on Earth, temperatures in reactors need to be even higher than the sun's core - 200 million degrees Celsius! Last year, CNL signed an agreement with General Fusion to work together on managing tritium in fusion energy systems. More specifically, the process of extracting tritium from liquid metal to provide a limitless supply of "fusion fuel."
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Frozen SOLID!
Monitoring the impacts of cold on concrete The nuclear industry uses concrete, and lots of it, in building reactors. Because of this, our industry also does lots of research to make sure that the concrete we use is doing what it is supposed to do. As we start to look to new reactor technologies like small modular reactors (SMR) and possible uses in arctic regions, we must make sure that we are understanding how cold conditions would affect this important building material. There are already a number of techniques we use to understand and monitor the condition of concrete. The questions that we must answer concern how well these same monitoring probes would work during extreme cold, or, throughout weather fluctuations; temperatures in the Canadian arctic region can swing from +34 degrees C in the summer to -58 degrees C in the winter months. These changes in temperature will create stress in the concrete, as well as the instruments we place inside. CNL’s Inspection and Monitoring Technologies team launched a project to investigate these questions.
Into an industrial sized freezer set to -30 degrees, the team put a 60 cm x 60 cm x 60 cm cube of concrete. Into this concrete cube were placed a number of sensors, including pairs of ultrasonic probes to monitor changes in the concrete’s strength, as well as 15 thermistors to measure the temperatures inside the concrete block. For the past several years, the block has undergone freeze-thaw cycles. The block is frozen to below -20 degrees C, and thawed to +4 degrees C over a period of two days. Then, the cycle begins again, and the block is cooled to -20 degrees C. The temperatures are monitored at the mid-way point. All the wiring is passed through a sealed access port, so there is no need to open the door. Through this cycling, we are able to understand the impacts of temperature fluctuations on the concrete, but also, it allows us to test our equipment to make sure it is durable enough to withstand the weather conditions in the Canadian arctic.
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Freeze plugs – A cool way to seal off piping In the core of a nuclear reactor (the reactor vessel) there are hundreds of pipes (fuel channels). To keep the reactor running safely, and to take away the heat energy used to make electricity, water is pumped through each of these pipes. A CA
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To get an idea of what this looks like, picture a handful of straws, each with water passing through them.
NDU6 reactor c ore.
The fuel channels are attached at each end to a larger pipe system known as a header. Water comes in one end and out the other - essentially a sealed loop. If a reactor operator needs to investigate part of this cooling system, they need to isolate the individual channel otherwise the water would leak out. To do this, the reactor operators use a technique called a “freeze plug”. This works exactly as it sounds. With the reactor shut down, a tool is used to wrap the fuel channel in a jacket or blanket filled with liquid nitrogen. The nitrogen is very cold, -196 degrees Celsius, and this freezes a solid block of water inside the fuel channel, preventing any water from leaking in or out. With the frozen ice plug in place, the team can then safely remove a section of the piping, or a piece of material. In many cases, here in Canada, those materials are then sent to CNL for us to investigate. We use our scientific equipment to examine the metal pieces and understand their condition. Once the fuel channel or reactor part has been repaired or replaced, the liquid nitrogen blanket is removed, the ice plug melts and the reactor can return to normal power again.
CANDU power reactors, the type we use here in Canada, use "heavy water" as a coolant. Heavy water freezes at a different temperature, 3.8 degrees Celsius, which is a little warmer than regular 'light water' which freezes at 0 degrees Celsius.
Freeze plugs are a very simple solution to what would otherwise be a very complicated challenge.
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Superconductivity A Magical Science? At very low temperatures (−196.2° C and lower) some materials can become "perfect" conductors of electricity. When cooled below certain temperatures, all of a sudden these materials simply show no resistance to electric current; electricity can travel through the material without any loss of energy! This phenomenon is called superconductivity, and it is being put to use in many different applications. When a superconductor is cooled below this certain temperature, it also repels magnetic fields from its interior. This means a magnet can levitate above, below or to the side of a superconductor. It’s also the science behind how the world’s fastest train, the SC-Maglev (superconducting magnetic levitation), works. Superconducting magnets in the train are cooled to extreme temperatures and cause the train "magically" to levitate or float 10 cm off the ground. With no longer any friction, it can travel at very high speeds. Essentially, the train is driving without wheels, or flying without wings!
The fastest SC-Maglev train can now reach speeds of 600 kilometres per hour. Not only do these trains get passengers to their destination faster than traditional trains and at speeds that can compete with airplanes, they do so with less impact on our environment. Superconductivity is also the science behind MRI or Magnetic Resonance Imaging, one of today’s most important medical imaging techniques. The very strong magnetic fields required in the technique can only be practically achieved through the use of superconducting magnets. The world’s strongest MRI machines are now pushing human imaging to new limits. The images of the human brain they can capture are unlike any captured before! There’s no doubt the science behind superconductivity is cool. At CNL, scientists have been studying the fundamental properties of superconductors for years and they are also just starting to look at the applications of these and other quantum materials in the area of safety and security.
Pictured: The Shanghai Transrapid Maglev Train (Photo Max Talbot-Minkin CC 2.0)
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CNL is testing a new special nuclear materials detector named ALARM (A Liquid Argon Radiation Monitor). While many countries already have effective systems for detecting special nuclear materials, in our Safety and Security program, we are always looking for ways to make improvements. The idea to use liquid argon as one of those ways. At the heart of ALARM is a sphere filled with liquid argon. Argon is what is known as a cryogenic material, and it must be kept very cold or it will turn into a gas. We keep the liquid argon at a temperature of -186 Celsius. And that’s without the windchill! If the argon warms up and turns into a gas, it would still work, but not very well. Radioactive materials are constantly “radiating” energy in the form of neutrons, or gamma, beta or alpha particles. If radiation passes into this liquid argon, the interaction creates a flash of ultraviolet light. The ALARM detector captures that light, amplifies it, and measures it. The amount of detected light will tell us the energy of the radiation. And, the energy of the radiation will help us determine what the material is which released that radiation. Although liquid argon needs to be kept very cold, it does have a lot of advantages over some of the current detector systems. Because it is liquid, it can be held in containers of all kinds of shapes and sizes depending on how you want to use the detector. And, secondly, it is inexpensive and easy to obtain. This year the team at CNL is working to assemble and preparing to operate the detector using the materials we keep safely stored in our secure labs. While the problems we’re trying to solve at CNL are more terrestrial in nature than dark matter, one never knows which “out there” idea in fundamental science is the key to making the world a safer and more secure place.
The li detec quid argon tor in than (-186 C) is the the su colde r moon face of th r e (-173 C)!
ALARMINGLY COLD!
CNL DEVELOPS DETECTOR SYSTEM WITH A VERY COLD HEART 7
Word Scramble!
Hide and Seek!
Are you able to unscramble these key words from this issue of Kids CONTACT? Send in a picture of your completed page to communications@cnl.ca and you just might win a prize!
Can you find all these items hidden in this issue of Kids CONTACT? Just write down what page you found them on in the small circle. Send in your entry, and you just might win a prize!
LODC NEZORF ETERCNOC SINOUF
Isla
RGAON NIETARG TRGONEIN QUIDIL CEI
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“Picture This” Challenge! For this issue's art challenge, we are asking you to draw us a picture of your favourite winter activity. When you are finished your artwork, send in a photo to communications@cnl.ca.
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In “Under The Microscope” we’ll feature a sample image taken in our materials science laboratories, allowing you a close up view of the world we live in. In this case, we are featuring a closer look at granite - this is the rock that curling rocks are made out of. The photos were collected in backscattered electron mode, which allows us to see areas within the sample that have different compositions.
ct #1 Fun Fa e made of ar stones low Curling nite that has h a rare gr sorption whic b a n of water e actio from h t s t n r preve g wate freezin tone. ly d e t repe the s eroding
N ICATIO AGNIF M X 0 25
Feldspar
AG 100 X M Titanium/Iron Oxide Quartz
N ICATIO AGNIF 50 X M
CNL Corporate Communications 286 Plant Road, Stn 700 A Chalk River ON, K0J 1J0 1-800-364-6989 communications@cnl.ca www.cnl.ca
TION NIFICA
Fun Fact #3 Granite is an ig neous rock, which means th at it was formed from m olten lava deep within the earth' s crust.
ct #2 in the Fun Fa t rocks artz s e ld o f the ly qu is one o of main n Granite is composed ranite is ofte d G n . a ls a iner world s and spar m s, floor and feld or countertop s. rock used f curling
If you have a question for one of our scientists, send it in by email to communications@cnl.ca. We'll get it in the next issue!
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