 Inside a nuclear reactor is a hot, stressful place. Like any other materials, components in a nuclear reactor are subject to corrosion and wear, but have the unique challenge of being irradiated 24-7 from nuclear reactions themselves. Knowing the microscopic structures of these materials and what they're made of help us build better and safer nuclear reactors. Most materials that we build are large structures out of. They do suffer from a very slow but manageable degradation phenomenon whether it's corrosion or deformation of the material. When we hear the word microscope, we often think of something like this. This is called an optical microscope and uses light traveling through a series of lenses to magnify the object that we're looking at. If we want to get an even better resolution and magnification, instead of using a beam of light, we can use a beam of tiny particles called electrons. Usually electrons can be found buzzing happily around atoms, but in this case, we're going to use them to help us see with this microscope. This is called a Scanan electron microscope. The sample we want to look at is placed inside this microscope. It works by focusing a beam of electrons onto the sample in the microscope. When the beam hits the surface, it knocks loose electrons from the atoms at the surface of the material. Detectors in the microscope capture the electrons escaping the surface. Because we're taking things only from the surface into the detector, that gives a surface topographic information or highs and lows, morphology type of information. So we now know what the sample looks like in almost three dimensions. As the microscope scans the surface back and forth, the data is used to create the image you see here. When the electron microscope takes images of a fractured metal, a dimpled structure appears indicating that the metal is flexible. The scale of this image is about 3.6 micrometers across, 25 times smaller than the thickness of a human hair. Zooming out to a larger scale, this image measures about 250 micrometers across, the width of about three full human hairs. The bands along the surface indicate brittle edges and are the weakest part of the material, which may fracture more easily than the rest. Using the electron microscope, we find traces of the element chlorine along the bands in the image, not normally found in this metal. So what we learned from this is that if we can get the chlorine out of the material, we can make a much better material and that's what we have in current generation reactors. Removing impurities like this one during manufacturing will help build stronger materials. This research at Chalk River Laboratories continuously ensures that reactor materials are built as safe as possible and will last for a very long time.