READ & WATCH: Meet new Queen's engineering professor, Suraj Persaud

Posted on March 05, 2018

By Matt Mills, FEAS communications staff

Canadian nuclear power technology has provided safe and reliable electricity at home and in countries around the world since the early 1970s. Nuclear power accounts for about 17 percent of electricity consumed in Canada. The original design-life for CANDU reactors was only 30 years but there have been no new nuclear power plants commissioned in Canada since the early ’90s and there are so far no definite plans for any more.

It’s no surprise then, that utilities place great value on developing new and innovative ways to extend the service life of existing nuclear power plants. In 2016, for example, the Ontario government announced plans to spend $12.6 billion over the next decade to refurbish all four reactors at the Darlington Nuclear Generating Station and to keep aging reactors at the Pickering Nuclear Generating Station online past their original service life through 2024.

Suraj Persaud

A NEW ADDITION: “The idea that we can predict cracking before it happens is a huge advantage to the newest microscopy methods,” says Assistant Professor Suraj Persaud.

Some of the metal components inside nuclear reactors endure temperature and pressure stresses as well as the prolonged effects of exposure to radiation. Critical components could be susceptible to corrosion issues and, in a system that depends for safety’s sake on its structural integrity, understanding these issues is an industry priority.

“Cracking is actually a long process,” says new Queen’s engineering professor, Dr Suraj Persaud. “Many of these reactors were built in the ’60s but may not exhibit cracking for 30 or 40 years. All these materials form surface oxides – surface films – that protect the material from corrosion. But these oxide films can become impaired in certain conditions leading to cracking. With current technology, there may be an opportunity to eventually pull a tube from a plant and examine the surface film, allowing us to predict cracking before it happens.”

Persaud’s research work and expertise is as an experimentalist investigating ways to continue to improve upon and develop new methods for predicting cracking in materials, especially in nuclear power facilities. It includes, firstly, building an ever-deeper understanding of the chemistry and mechanical properties of materials, and the behaviour of materials in corrosive environments. Dissolved sulphur in high temperature water, for example, can impair the surface film on a steel component increasing the likelihood that cracks will form. And secondly, using the latest techniques in electron microscopy and surface science, on smaller and smaller scales, to learn more about how cracks typically initiate and propagate.

The results can be used in partnership with utilities and national laboratories to help understand potential cracking problems. They can also be used in concert with mathematical modellers to help design components that have optimal properties for their specific applications. Ultimately, though, the ability to make the most accurate possible predictions about when, where, and how cracks will form might be the most useful fruit of this research.

It’s work that could save taxpayers piles of money, ensure that nuclear power plant components are safe and serviceable for years or decades to come, ensure infrastructure is in place to meet growing demands for electricity, and simultaneously protect public safety.

Persaud earned his PhD from The University of Toronto in 2015 and worked in the interim at the Canadian Nuclear Laboratories in Chalk River. As a new assistant professor, he is one of four recent faculty additions to the Department of Mechanical and Materials Engineering here at Queen’s. He’s about to start building his research group and he’s recruiting graduate students.

“I hope to do applied projects in partnership with utilities but I also plan to use cutting-edge technology to study corrosion at the atomic scale,” he says. “We’ll be using and expanding on techniques that have only been around for three or four years. If someone comes to my lab group, I want them to leave feeling they are actually on the cutting edge of science.”

Visual aid: Atom-by-atom reconstruction of a crack

NEW METHODS: Dr Persaud plans to continue to develop innovative methods for understanding how cracks form, even at the atomic level.