Burying nuclear waste

by Tyler Shendruk
Published: Apr 4

The problem

A FIFTH OF the world’s uranium comes from Canada. CANada Deuterium Uranium (CANDU) reactors have been safely running since the 1950s, but nuclear energy is not without its problems. A handful of leaks have occurred, raising questions about waste management.
Storage of nuclear waste is a particularly important question right now as there is a proposal to build up to four new nuclear reactors at the Darlington Nuclear Generating Station on the northwest shore of Lake Ontario.
Plans to ship waste to depositories in the shield are controversial amongst northern communities and many critics are uncomfortable with the idea of transporting nuclear waste over such long distances.

The researcher

Ian Clark is a professor in the Department of Earth Sciences at the U of O who uses the environmental isotopes found in nature to investigate deep crustal water and geochemical and biochemical processes that occurred millions of years ago.
Clark drills for rock samples and then analyzes the water and gases that have been trapped in these rocks for millions of years. He can determine if the groundwater has been totally isolated or if, over millions of years, new water has been slowly moving through the rocks.

The project

Clark uses natural isotopes as a tool but that knowledge is also extremely useful for predicting the outcome of burying nuclear waste. He was asked to be part of a team that would assess a site at Kincardine in southern Ontario, close to both the Darlington and the Bruce Nuclear generating stations.

The key

The Northern Shield may sound like the perfect place to bury nuclear waste, but according to Clark, it’s not. Yes, the igneous rock making up the shield is hard so nuclear waste shouldn’t diffuse through it, but it has fractures. The shield is leaky because faults let water flow quickly from one point to another.
Kincardine is much better according to Clark. He analyzed rock samples from six holes drilled 850 metres down to sedimentary rock—formed from deposited sand and clay at the bottom of ancient oceans—at the Kincardine site. Clark ground up these rocks and baked fistfuls to get about two drops of water, water that had been trapped for some 400 million years. Helium was also trapped in the rocks for more than 260 million years.
As these rocks are very tight and don’t fracture, and the site is very close to Ontario’s fleet of nuclear reactors, Clark believes Kincardine is an ideal environment and much better than any in the shield to bury nuclear waste.

The ice that shapes the Earth

by Allan Johnson

Published: Mar 28

 

The problem 

THE GREENLAND AND Antarctic ice sheets are melting at an accelerating rate, and we’re not sure how that melting is going to change in the future.
Ice sheets are a metre stick for climate change, but measurements of the Greenland ice sheets’ past changes are in disagreement with physical models. In fact, models underestimate the effect rising temperatures will have on ice and sea levels, and things might get even worse.
If we want to avoid stumbling into the future blindly, it’s vital we understand how ice sheets have responded to climate change in the past and how that, in turn, will affect the world in the future.

The researcher

Benoit Lecavalier is a graduate student working with professor Glenn Milne in the departments of physics and earth sciences at the U of O. By using computational modeling, he works on reconstructing the evolution of the Greenland ice sheet from the peak of the last ice age to the present moment using field observations.

The project

By attacking the problem of ice thickness from a geophysical perspective, Lecavalier is able to address the overall system as a set of interlocking feedback loops—when temperatures rise, the ice coverage begins to melt, and the melting ice raises sea levels.
But what’s not so obvious is the ice sheets are so heavy they deform the planet itself. When they melt, the removed weight causes the planet to reshape, making sea levels on the other side of the planet rise even more. The Earth itself behaves like a giant, slow-moving fluid, responding to pressure from the ice.

The key

By considering the physical processes of the Earth’s deformation and subsequent reshaping, it’s possible to take a second look at the history of Greenland’s ice sheet, considering not only sea level, temperature, and past ice extent, but also the fluid response of the Earth.
Considering this additional set of constraints, Lecavalier is able to improve the agreement between the ice model and field observations. This improves our understanding of how ice sheets behaved in the past, which helps us better comprehend their behaviour today and predict their future.
Since there were times in the past when the Earth was this warm, understanding how ice responded then gives geophysicists a chance to glimpse the future today.

Nanoengineering cyborgs

by Tyler Shendruk
Published: Mar 14

The problem

CYBORGS AREN’T SCIENCE fiction. All around us people with pacemakers, insulin pumps, and prosthetic implants continue to live normal lives because of mechanical and electronic parts within their bodies. It’s not sci-fi; it’s mundane.
But that doesn’t mean combining human bodies with technology is scientifically simple. Even relatively straightforward implants need to be biocompatible or human tissues won’t accept them. Implants also need to be reliable.
We may take it for granted, but our bodies are amazingly robust. When we sustain injuries, we heal—but implants don’t. Hip replacements are some of the most successful prosthetics, but even they have a 20 per cent failure rate after 20 years.

The researcher

Amirhossein Ketabchi came to Canada to do his undergraduate degree in engineering at the University of Ottawa. Here he found a tight-knit community of students and decided to stay in Ottawa to continue graduate studies. Ketabchi is now a master’s student in the Surface Nanoengineering Laboratory with an interest in medicine and bio-materials.

The project

Titanium is one of the best bio-materials for implants. It’s light, strong, non-toxic, resistant to corrosion, and isn’t bad at osseointegration—the merging of bone and non-bone into a single object. Not all metals are good at this, but titanium isn’t bad. Ketabchi thinks he can engineer it to be better.

The key

In order to engineer better biocompatibility, Ketabchi modifies the surface of the titanium. Because your body’s cells are in contact with implants, modifications must change nanoscopic details. Ketabchi does this nanoengineering by dipping titanium into an acid mixtures. The acid causes an oxide layer of open nanotubes to form on the surface of the titanium, which human bone can then grow into. Nanoengineering the surface of titanium like this improves its biocompatibility.
But soaking metal in strong acid for hours and hours weakens it, and the last thing you want is a titanium pin in an implant snapping. So Ketabchi knows there has to be a tradeoff between biocompatiblity and preserving strength to withstand years of fatigue. He tests the endurance limit of pin after pin, looking for the perfect compromise between biocompatibility and strength.

Explosive super sensing

by Allan Johnson
Published: Feb 29

The problem

A FEW YEARS ago there was a worldwide hike in food prices because the United States made incentives for making biofuels—gasoline with ethanol, an environmentally friendly alternative to regular gas—attractive. The need for biofuels is clear, but how do we tell if manufacturers are actually making fuel from crops and not just repackaging normal gas and charging double?
Seemingly unrelated, Vancouver sits directly over a relatively quiet fault line—a place where the pieces that make up the Earth’s surface meet. How quiet the fault line actually is, however, is difficult to determine without a history of its past activity.
There is also a need to monitor our nuclear waste, making sure that none of it is being spread from secure storage.
The solution to all these problems lays within tiny quantities of telltale radioactive isotopes that give the necessary history. How can the history of a few atoms within an isotope be detected to solve all of the above and similar problems?

The researcher

Liam Kieser is an associate professor of physics at the University of Ottawa and the director of the IsoTrace Laboratory in Toronto. He works on using accelerator mass spectrometry (AMS) to reach unparalleled levels of sensitivity, finding the smallest traces of isotopes that would be undetectable normally.

The project

AMS uses a particle accelerator to bombard a sample with fast-moving particles, freeing and ionizing them. Imagine billiard balls hit with a wrecking ball. The atoms in the sample shoot out, guided by electric and magnetic fields. Different masses move differently in the field and researchers can pick out the particles of interest by their mass.
Thanks to the high energy projected from the mass spectrometer, molecules that might have the same mass as the isotope in question explode into fragments, which no longer have the same mass. On the other hand, the isotopes come out with so much energy that techniques from particle physics can be used to detect them down to the single atom level. Altogether, AMS can detect the presence of an isotope down to a millionth of a billionth of a gram.

The key

Kieser works on ways of further increasing the sensitivity of AMS, devising methods of separating not just isotopes from molecules of the same mass, but isotopes from other atoms with the same mass. While molecules can be split easily, the other atoms are effectively indestructible.
Recently he’s developed a method for separating Sulphur 36 from the radioisotope Chlorine 36. Chlorine 36 is of great interest in ground water studies, since a great deal was generated during nuclear testing in the 1950s. Upon completion of the Centre for Advanced Photonics and Environmental Analysis at U of O, Canada’s only accelerated mass spectrometer will move to Ottawa in a new state of the art lab, providing the tools for extreme sensing.

Crammed in the capillaries

by Tyler Shendruk
Published: Feb 9

The problem

DO YOU EVER stop to think about your cells’ needs? Every one of the trillions of cells making up your body requires energy and is fed by blood. Armies of red blood cells continually parade through the heart, to the furthest backwaters of your body, and back again.
To get to every part of your body, the capillaries that conduct these nutrient-carrying cells to their destinations must be tiny. Blood cells are forced to march single file through severely confining micro-veins. In fact, the blood cells are actually 25 per cent larger than the smallest capillaries they travel through. How can this be?

The researcher

Alison Harman is a graduate student in the Department of Physics at the University of Ottawa. As a physicist, she is more interested in the mechanics of cells than anything else. She doesn’t worry about the fact that the cell is alive. Instead, Harman uses simplified computer models to simulate the physical properties of cells.
These virtual cells are still complicated, but they are simple enough that Harman can extract information about cellular membranes without worrying about the intricacies of life.

The project

Harman models the blood cells, simulating each of the lipids that make up the cell membrane, but not the contents of the cell. Each of the lipid molecules are made up of a head that likes water and a tail that avoids water.
To keep everyone happy, the lipids organize themselves into a bi-layer with tails facing in and heads facing out, which results in an empty vesicle.

The key

Vesicles are most comfortable as spheres, but they are very deformable. When they are carried through fairly large capillaries, the flow pulls them out into a flat, parachute-like shape. Faster flow stretches the vesicle longer.
Harman’s simulations show this stretching happens at the edges of the parachute. At very high flow rates—about 100 times faster than blood actually flows in the body—the vesicles eventually break.
Harman sees a different picture in the smallest capillaries. The vesicles are so crammed they must fill the entire tube of the capillary and deform into a pill-like shape. As the flow rate increases, vesicles stretch until they can’t stretch anymore. They usually break along their side where the membrane is closest to the wall, fitting into the capillaries.

Troubles with texting

by Allan Johnson
Published: Jan 25

The problem

LOOK AT THIS article. Now at your phone. Now back to this article. Chances are, you have plenty of text messages saying something like, “OMG, ttyl, g2g”—or at least that’s what some people might expect.
Expectations aside, there isn’t much scientific knowledge surrounding texting habits. Texting is private, and finding information about how texts are created is much more complicated.

The researchers

Elizabeth Marshman, assistant professor at the University of Ottawa’s School of Translation and Interpretation, and Lynne Bowker, chair of the School of Information Studies at the U of O, are trying to separate fact from fiction when it comes to texting.

The project

Marshman and Bowker head the Ottawa branch of text4science, a collaboration of Canadian researchers building a data set of text messages and demographic information about texters for scientific study.
Research volunteers provide information about their texting habits, language usage, and aspects of their day-to-day communications—with personal information kept confidential—and then forward their text messages to text4science. The goal is for the project to gather 100,000 text messages, and combine the data obtained in Canada with findings from similar projects in Europe.

The future

According to Marshman, “One of the things that’s really interesting … is that we don’t know what we’re going to find.” This research is considered exploratory  because so little is known about texting.
The researchers hope results will show how people compress ideas into texts. They’ll also look into how French and English mix in texting and what kind of variation there is in abbreviations used. Is “c u l8tr” a universal choice, or is there more creativity involved in conveying the phrase?
Bowker also hopes the data will lead to automatic translation mechanisms for text messages, allowing texters to stay in the loop without struggling to read through a mess of unfamiliar abbreviations.
If you’re interested in participating in the study by donating your text messages, visit Text4science.ca Participants are eligible for weekly prize draws.

LEED at the University of Ottawa

by Tyler Shendruk
Published: Jan 11
as an inset to Christopher Radojewski's
Social sciences under one roof

THE LEADERSHIP IN Energy and Environmental Design (LEED) is a rating system for judging green construction projects. Buildings are given a total of 100 possible points assessing the sustainability of the chosen site, water efficiency, energy and atmosphere impact, materials and resources used, quality of indoor environment, and 10 bonus points for innovative design and regional priority.

The number of achieved points gives the structure a grade:
Certified: 40–49
Silver: 50–59
Gold 60–79
Platinum: 79+

In 2008, the University of Ottawa’s Campus Sustainability Office pledged all new and retrofitted buildings would achieve Silver rating or higher.

What makes it green?

Green wall (also called a living wall).
One huge wall of the atrium will be entirely covered with vegetation and act as a natural air filter.

Heat recovery ventilation system 

Even with the green wall, some ventilation is needed, but exchanging warm indoor air with cold outdoor air (or vice versa) is a waste of energy. By processing the air before it leaves or enters the building, the ventilation system will keep 90 per cent of its heat.

Green roofs 

Three of the roofs will be covered in growth. This follows a strong tradition: The Colonel By building, built 40 years ago, was one of the first green roofs on a Canadian campus.

Data furnace 

The tower is designed to receive 80 per cent of its heat from local campus computers.

Natural light 

Only five per cent of the tower will require lighting. The rest will be naturally lit.