Look inside a nano testing machine

October 14, 2011
By: Science Today, University of California

Peter Hosemann, Nuclear engineer/UC Berkeley: Currently in the U.S., we get about 17 percent of our energy from nuclear energy. It's important that we make sure that we have a reliable and safe
source. And so our research for example is focusing on long-term reliability of materials
used in nuclear power plants, if lifetime extension can run them longer?

We can deal with much smaller amounts of radioactive materials, which makes it safer for the
students and the scientists to handle that material because it's less radioactive sources
one has to handle.

Andrew Minor, Material scientist/UC Berkeley: These new tools that have become available, the tests become much more sophisticated and we get much more relevant and useful information. Some practical implications like materials handling is easier so you don't have to have huge amounts of radioactive material to be able to able to for instance test it. You can investigate new materials in an easier way because let's say you make some new material in the lab, you're not going to make a whole lot of it. You're going to make a little bit. That's the easiest way and then you can irradiate it and test it.

So, if you actually look at the whole scope of the experiments, the materials were first prepared at Los Alamos and then they actually came to Berkeley and we used a special machine to machine them to the right scale and then we used a very special holder to test these inside a TEM, inside a transmission electron microscope. It's really an amazing machine. So, what it really does is not only image specimens with the electron microscope, so you can image down to say the nanometer level, but you can also machine the sample down to the nanoscale with what is called a focused ion beam. So, basically it is like a sandblaster, but instead of using sand you
use ions.

So, as you see inside the chamber here, this is what's the pole piece for the
electron beam and this is the pole piece for the focused ion beam and they're aimed at the
same spot. So, what that lets you do is cut something while you're looking at it at the
nanoscale at the same time. What's also really nice is that by doing it inside an electron microscope you can actually view fundamental processes of deformation so you really get much richer information.

Radiation causes materials to accumulate defects at high densities and so what you're
really testing in terms of safety, in terms of the metallurgy that's in a reactor, what
you're doing is really testing to see when this metal becomes brittle.

Peter Hosemann: So, you have to expose a material in a reactor which takes 10, 20, 30 years to get a dose to make assumptions of what the long term behavior of what the material is. Having tools which accelerate this process help us to find better materials for the next generation of nuclear power plants.