Phoenix Neutron Imaging | Phoenix Demonstrates Highest Possible Neutron Image Quality At New NDT Facility

After much hard work from our engineers, we have now demonstrated the capability to take ASTM Category I neutron radiographs at our new accelerator-based industrial radiography facility, the Phoenix Neutron Imaging Center (PNIC) in Fitchburg, Wisconsin. Though we’ve come close in the past, this is the first time we have managed to meet and exceed all of the criteria set forth by ASTM International regarding the highest possible quality of neutron images. ASTM Category I images are the highest image quality level specified by ASTM E545, the gold standard for defining the quality of neutron radiographs, and until now only nuclear reactor facilities were capable of producing the magnitude of neutrons needed to create Category I images.

It isn’t just about neutron yield, though, though having the most powerful fusion neutron generators in the world plays an important role. It’s about the whole system. Every little detail about the materials used in the system and its design plays a role in squeezing out as much quality as possible. This milestone wouldn’t have been possible without our engineers at PNIC giving it their all to make our neutron radiography system the best it can be.

Neutron imaging has always lagged behind its cousin, X-ray imaging, because whereas X-rays were comparatively easy to produce, neutron radiation has always required nuclear reactions and thus advanced nuclear technology. When Phoenix began constructing its first neutron imaging system back in 2012 under a Small Business Innovation and Research contract with the US Army, the idea that a compact neutron generator that used nuclear fusion could create high-quality neutron radiographs was still just an idea. Reactor facilities were still the kings of quality, being the only neutron imaging vendors capable of producing Category I radiographs. The ability to generate ultra-high-quality neutron images with a small, relatively low-cost, accelerator-based neutron imaging system is truly an industry game-changer. With the Phoenix system able to duplicate reactor throughput as well as quality, this marks a turning point in the realm of N-ray analogous to the early use of compact x-ray generators in medical diagnostics over a century ago. It is a first step in making neutron imaging as ubiquitous as x-ray imaging is today.

Read the full press release here.

The X-ray image (left) cannot clearly depict the cooling channels in a batch of blades; however, the channels show up more clearly in a neutron image of the same batch (right).

Aircraft Turbine Blades X-Ray/Neutron Imaging Comparison

The manufacturing of jet engine turbine blades is one particular industrial niche for neutron radiography. Turbine blades are cast around ceramic molds which form cooling channels that prevent the blades from melting when exposed to the high temperatures of their operating environments. In manufacturing, fragments of ceramic can clog these cooling channels. A blade with clogged cooling channels could break or even melt while in operation, so such flaws must be rooted out with 100% certainty. The X-ray image (left) cannot clearly depict the cooling channels in a batch of blades; however, the channels show up much clearer in a neutron image of the same batch (right).

gadolinium tagging

This cross section of a turbine blade shows off one of the most useful and unique applications of industrial neutron radiography. The only way to reliably detect the ceramic fragments which can be left within a blade’s cooling channels is to wash the blade in a solution containing gadolinium, an element with a high neutron cross section. Once the gadolinium has permeated the ceramic’s porous structure, the fragments will show up in stark contrast on the resulting neutron image even after the solution has been rinsed off of the rest of the blade.

Beretta 92FS Neutron/X-Ray Imaging Comparison

Neutron radiography is especially useful for imaging munitions. In this neutron image, neutrons interact with parts within the firearm and show details that a high-energy x-ray would not depict, even the presence and position of gunpowder in the cartridge.

170kV X-ray imaging

440kV X-ray imaging

Neutron imaging

Rotary Telephone X-Ray/Neutron Imaging Comparison

X-rays and neutrons interact with materials differently, creating unique images. This rotary phone is comprised of many dense and light materials. The lower-energy 170 kV X-rays could not penetrate the denser materials of the phone. The higher-energy 440 kV X-rays could penetrate the denser materials, but was too high-energy to create an image of the lighter materials. The neutron beam could penetrate dense materials but not light materials, creating neutron radiograph that shows more detail of the phone’s inner workings than either X-ray image could on its own. The difference in how neutrons interact with light materials is what makes neutron radiography such a powerful complementary tool to X-ray radiography in materials science, materials research. and non-destructive testing applications.

Flower Neutron Images

Flowers tend to show up very distinctly on both neutron and X-ray images. However, water has a very high neutron scattering cross section, which makes neutron radiography and tomography useful for studying water uptake within root systems and rooted soil.

60kV X-ray imaging

140kV X-ray imaging

200kV X-ray imaging

Neutron imaging

Hand Plane X-Ray/Neutron Imaging Comparison

With examples such as this hand plane, it’s “plane” to see how neutron radiography and neutron images can show you details that can’t be seen with X-ray radiography. These three X-ray radiographs of varying energies, looked at as a whole, all together show almost as many details as a single neutron picture!

Welding flux on a copper plate (photo)

Welding flux on a copper plate (X-ray)

Welding flux on a copper plate (neutron image)

Welding Flux X-Ray/Neutron Imaging Comparison

Like gadolinium, boron has an extremely large neutron cross section that makes it useful as a contrast agent in neutron imaging, among other things. In this example, welding flux, which contains large quantities of borax, attenuates neutrons particularly well compared to metals such as copper. This makes neutron imaging useful for assessing the quality of welds and making certain that undesirable remnants of flux do not remain on a welded part.

MORE ON boron's neutron contrast properties

An X-Ray image of the fuel injector structures.

An N-Ray image of the fuel injector structures.

The X-ray images (top and center) miss important details regarding the fuel injectors’ structure. The N-ray image (bottom), on the other hand, offers more detail than either X-ray image alone.

Fuel Injector X-Ray/Neutron Imaging Comparison

As with the images of the rotary phone, these fuel injectors depict the differences between high and low energy X-ray images as well as neutron imaging. The image taken with 100 kV X-rays misses important details regarding the fuel injectors’ structures because the X-rays cannot easily penetrate the dense outer layers of material. However, the image taken with 190 kV X-rays also misses important details because while the X-rays can pass more easily through the denser material, they also pass too easily through the lighter material as well. Neutron imaging, on the other hand, offers more detail than either of the X-ray radiography images on their own.

In particular, two of the fuel injectors have been clogged with contaminants (we used ketchup, butter, and mustard), which show up as white blockages in the plugs in the neutron image and do not show up at all in the X-ray images. This shows the value of neutron radiography and tomography in rooting out defective parts and other non-destructive testing applications!

INTERACTIVE N-RAY/X-RAY COMPARISON

Click and drag on the vertical line to compare X-ray radiography and neutron radiography images. One advantage neutron imaging methods offer over the X-ray images is that details that did not show up on either the high-energy or low-energy X-rays, such as blockages within the fuel injectors, are visible.

225kV X-ray image

400kV X-ray image

Neutron image

Proxivision Ball Bearings X-Ray/Neutron Imaging Comparison

Click and drag on the vertical line to compare X-ray and neutron images.

Neutron Imaging of Hard Disk Drives

Because of the way neutron beams pass easily through dense metal components, the neutron image of the 3.5″ hard disk drive on the left mainly shows the less dense plastic components of the hard drive’s internal structure. the 2.5″ external hard drive on the right is entirely encased in a plastic shell which is more opaque, but not entirely opaque, to the neutron beam.

INTERACTIVE N-RAY/X-RAY COMPARISON

Click and drag on the vertical line to compare X-ray and neutron imaging. To neutron tomography, most of the metal components of the hard disk drive, such as the faceplate, the read/write heads, and the disks themselves, are completely transparent, allowing a clearer look at some components that are not as visible, if at all, in the neutron radiograph compared to the X-ray image.

We’re batty for neutron radiography at Phoenix!

Unlike X-rays, neutrons are attenuated heavily by flesh and muscle, giving a unique perspective to the radiographic image of these bat specimens. That is one of several reasons why your dentist probably isn’t interested in shooting neutron radiation at your teeth during your dental check-up.

Neutron Radiography of Consumer Electronics

Neutron radiography can provide an interesting look into consumer electronics. As in the hard drive images, the plastic tends to be more opaque to neutrons in the neutron beam than most of the electronic components, providing a unique view of the structures of these items.

Photograph

X-ray image

Neutron image

Personal Safe X-Ray/Neutron Imaging Comparison

Your secrets aren’t safe from X-ray vision or neutron vision, but both forms of radiography show quite different perspectives in these images. Plastic components, which are rich in hydrogen, are particularly opaque on the neutron images but much more transparent on the X-ray images due to the high neutron attenuation of plastics and other hydrogen compounds. A closeup of the Honeywell safe shows that neutron imaging could even pick up on the details of the embossed logo on the door to the safe!

Flashlight X-Ray/Neutron Imaging Comparison

Both neutron radiography and X-ray radiography can offer distinct advantages over each other. In these images, both depict unique features of the flashlight in question. Phoenix is currently working on imaging methods to seamlessly combine the data from X-ray and neutron imaging together into hybrid images, which would allow for an unparalleled look into an object’s inner working for cases in which both X-ray radiography and neutron radiography provide indispensable data.

*N-ray image on top. X-ray image on the bottom.

Neutron Radiography of a Jar of Staples

Click and drag on the vertical line to compare X-ray and neutron imaging. For a rather offbeat comparison of the strengths and weaknesses of X-ray and neutron imaging, we filled a glass jar with staples and a single plastic figurine. In the X-ray image, only the staples are visible. With neutron imaging, the staples are far less visible, but the figurine hidden within is entirely visible as the neutrons interact more heavily with the plastic.

Phoenix Demonstrates Highest Possible Neutron Image Quality At New NDT Facility