Recent media reports tell alarming stories from the United States to Uzbekistan about volumes of missing radioactive materials, with headlines warning of the potential for terrorist attacks using these nuclear materials. It's no surprise then that understanding and learning how to deal with the real threat from Radiological Dispersal Devices (RDD), known commonly as "dirty bombs," is of top concern to the national security of countries around the world.

Canadian nuclear scientists are working on the battle frontlines of RDD research, determining how dirty bombs can be constructed and assessing associated risks. RDDs use conventional explosives, but are packed with nuclear materials, which when detonated can be dispersed over a wide area, and thus are considered particularly dangerous threats.

"It's definitely heavy-duty work, but the reality is that there are threats to Canada and somebody has to deal with them, and I have the scientific background to contribute," says Carey Larsson, Defence Scientist for the Radiological Analysis and Defense Group at Defence Research and Development Canada.

Larsson's own research was directly born out of the 9/11 attacks and the need to support science and technology involved in counter terrorism. As part of a $7.7 billion security package announced in the 2001 federal budget, the Department of Defence set up a five year $170 million inter-departmental fund to address chemical, biological, radiological, and nuclear (CBRN) threats and possible responses and necessary preparedness in case of a terrorist attack. It is the Defence Department's CBRN Research and Technology Initiative (CRTI) that funds Larsson's work.

"Funding is ample to say the least, and a lot of the work that my radiological group has really comes from the CRTI," says Larsson.

One of her projects involves developing a testing technology that pinpoints the trace fingerprints of radioactive material that may have been stored and eventually moved to a different location. "We can basically go into a terrorist's apartment and confirm that he had in his possession nuclear material," adds Larsson.


Carey Larsson places a sample in the Optically Stimulated Luminescence (OSL) reader to measure its stored radiation signal. Photo credit: Janice Lang, DRDC Ottawa.

Her other specialty involves understanding the inner mechanics of dirty bombs and how they are constructed and deployed. She hopes that the results of this project will help in evaluating the risk of specific materials being in certain devices. "Our work provides the tools for the intelligence and defence communities to guide their planning and their potential response to an RDD," she explains.

Wrench in the Plans

Looking back at how she got to her present position as a defence scientist, Larsson believes that it was simply a matter of grabbing opportunities and keeping an open mind. "If something strikes my fancy, then I'm willing to jump in and go where it takes me."

After completing her Masters in medical physics with a specialization in radiation biology at Ottawa's Carleton University in 2001, Larsson wanted to expand her research horizons. So she dove straight into a PhD on medical imaging, focusing on positron emissions tomography (PET). "It was a bit of a jump, but I do like different things and testing myself in different areas."

Two years into her doctorate studies she received an e-mail that would totally change her career. A friend e-mailed her a job notice outlining a position at Defence Canada that just seemed too interesting to pass up -- so she applied on a whim, not thinking much of it. As luck would have it she landed an interview, and a month later got a call back with an offer for a position. "While I was excited, it kind of threw a wrench in my plans, and made me stop and think and really figure out what I wanted to do."

At that point she had to make the most difficult career decision of her life. Would she continue her studies or switch careers and become a government scientist? "I definitely went through a lot of soul searching," Larsson remembers.

With encouragement from her husband and support from her thesis supervisor, she decided to pursue this unique career opportunity at the government. Her biggest concern, however, was to see if she could continue her PhD part-time. She took a year off from her studies and started working for Defence Canada in October 2003 and tried to pursue various avenues to continue her thesis but soon she realized that the timing was not right.

Larsson hasn't given up on doing her PhD though. "I have always wanted those extra letters behind my name." She hopes to pick up her studies again sometime in the next five years, while still at her current job.

"We do a lot of applied research here, and I can definitely foresee that the work that I do could definitely be applied to a valid PhD thesis that I could write up on the side -- so I'm keeping those options open right now."

A Day's Work

Making the transition to nuclear defense scientist was an obvious one for Larsson. In medical imaging one has to have a lot of knowledge of how radiation is emitted from patients that are injected with tracers. "You have to know how radiation works and that is fully applicable to the radioactive defense applications," she explains.


Carey Larsson (left), wearing an NBC suit and mask, takes radiation readings with a colleague during a radiation exercise. Photo credit: Ted Ostrowski, DRDC Suffield

While this work may sound risky and downright dangerous to many, Larsson sees excitement that motivates her every workday. One aspect of her job has her training to act as a scientific responder to a radiological terrorist event. This involves getting dressed in the chemical, nuclear and radioactive suits, complete with gas masks, and going out in the field with detectors. This brings her up close with danger of her work.

When working with radiation, you have to be aware of the risks. Exposure is strictly limited, according to Larsson, and she is constantly monitored for exposure.

"You don't really stop and think about being scared because you're more focused on the science."

Much of the research is a healthy mix of theoretical work and bench work with more than a third of Larsson's time spent in the lab working up experiments. A significant amount of her days are also spent doing in-depth literature reviews, harvesting data on radioactive materials, and writing government reports. Any remaining time is usually taken up doing field exercises that test response capabilities to RDD events.


DRDC Ottawa Defence Scientist Carey Larsson provides scientific advice during a radiation field trial. Photo credit: Janice Lang, DRDC Ottawa

Top Secret

Working on classified projects related to national security can have its own unique challenges -- like when it comes to talking shop with friends and family. It's normal to want to share your daily happenings at work, Larsson says, but you may have to give an edited version of what happens at work. "There have been a couple of times where my husband is edging to find out more, but he has just gotten used to the fact the he can't know everything." In instances where she needs to get something off her chest, Larsson finds comfort with her colleagues, where she can have a relaxed conversation about classified topics.

"Being a physicist, people don't really know what you're doing anyway," she says jokingly. "Both my parents tried to read my masters thesis and got through the first page and said -- oh, that's great, and put it down!"

Larsson thinks there will be a lot of growth in RDD research, particularly opportunities to partner and do bilateral projects with the U.S. and other countries in the near future. For her own career plans, Larsson believes that there are still yet many opportunities to pursue in different areas within Defence R&D Canada; so much so that she expects to be "sticking around for the long haul."

For a closer look at science career opportunities in the Department of Defence, visit the agency's Web site.

Andrew Fazekas is Canadian Editor at Next Wave and may be reached at afazekas@aaas.org

Andrew Fazekas is a correspondent at Next Wave and may be reached at afazekas@aaas.org.