Brookhaven National Laboratory Develops Integrated X-ray Imaging Tool for Nuclear Materials Research

A research team at the U.S. Department of Energy's Brookhaven National Laboratory has recently developed and built a new experimental apparatus that integrates four X-ray computed tomography techniques into a single instrument, enabling multiscale, comprehensive studies of next-generation nuclear reactor materials. The related technical achievements and capability demonstration have been published in the Journal of Synchrotron Radiation.

The apparatus is located at the X-ray Powder Diffraction (XPD) beamline of the National Synchrotron Light Source II (NSLS-II) and was commissioned jointly by the U.S. Department of Energy Office of Nuclear Energy's Nuclear Science User Facilities program, Brookhaven National Laboratory's Nuclear Science and Security Department, and NSLS-II. Researchers said that next-generation nuclear reactor materials are exposed to extreme environments such as radiation, corrosion, high temperatures, and mechanical stress over extended periods. Traditional research methods often require multiple instruments and multiple experimental workflows to obtain relatively complete information, whereas the new apparatus can perform multiple imaging analyses on the same sample.

The four techniques integrated into the apparatus include X-ray absorption CT, X-ray fluorescence CT, X-ray diffraction CT, and pair distribution function CT. The different techniques can respectively reveal the physical structure of a sample, its elemental composition and distribution, the atomic arrangement of crystalline materials, and local structural information of amorphous materials. Leveraging the high-energy "hard" X-rays produced by the XPD beamline, researchers can penetrate and analyze high-density, high-atomic-number materials such as steel and nuclear fuel; meanwhile, the beam can be focused to approximately 15 micrometers in width, thereby achieving structural and chemical composition maps with relatively high spatial resolution.

Researchers at Brookhaven National Laboratory explained that radiation can alter material structures, introduce defects, and cause elemental redistribution. By simultaneously using four CT techniques, researchers can locate where chemical changes occur and correlate them with changes in material strength and brittleness, thereby more clearly establishing the relationships among structure, composition, and performance.

To validate the apparatus's performance, the research team prepared a test sample containing metal wires of different sizes and compositions as well as various powder materials. Experimental results showed that the system can simultaneously identify the positions of different elements, atomic arrangements, and material structures. Completing the four types of tests separately using different instruments could take hours or even days; the integrated apparatus completed the experiment in approximately 6 hours. The research team is advancing equipment upgrades, hoping to shorten testing time to within 30 minutes to improve experimental efficiency and expand user capacity.

In addition to nuclear materials research, the apparatus has also been used to probe the internal structure of porous materials in water remediation and energy technologies, and is currently supporting research on battery charge-discharge processes and other materials under extreme conditions. Researchers said that this new experimental station will help the scientific community study materials for nuclear applications and related fields in ways that were previously difficult to achieve, providing support for the development of next-generation nuclear reactor materials.