What Is Neutron Radiography?

The field of NDT is comprised of a wide array of techniques used to evaluate the properties and structures of materials without causing damage to them. NDT is often performed for research and development, quality assurance, or failure analysis.

Common NDT techniques to discern the inner structure of a material or component include ultrasound, liquid penetrant testing, radiography, eddy current testing, and coherence interferometry. Each technique is unique and adapted to a specialized purpose, and each has its own advantages and disadvantages.

There are several methods of radiography used by NDT professionals: gamma ray, neutron and X-ray radiography. These methods all function roughly the same way; however, the differences between X-rays, gamma rays, and neutron radiation lead to very different results when you use them to image an object.

X-rays and gamma rays interact strongly with dense materials, but pass easily through lighter materials. However, neutron radiation passes easily through many dense materials, while interacting strongly with light elements such as hydrogen. As a result, many materials and components that would be difficult to inspect using X-rays and gamma rays are more easily analyzed using neutrons.

There are many applications in the non-destructive testing industry that neutron imaging is well suited for. Since neutrons can penetrate high-density material in a way that X-rays cannot, neutron radiography is widely used for critical aerospace components with thick outer shells, such as turbine blades and energetic fuses, which are difficult to inspect using X-rays. Neutrons can also be used to detect water and moisture within components, as well as archaeological specimens encapsulated in material that X-rays cannot penetrate.