Trace Impurities Identified as Forensic Signatures in CMX-5 Fuel Pellets Using X-ray Spectroscopic Techniques.

Area of Science:

• Nuclear forensics
• Materials science
• Analytical chemistry

Background:

• Small-particle analysis is crucial for interdicted special nuclear materials.
• Integrating microstructural, compositional, and molecular signatures advances forensic capabilities.

Purpose of the Study:

• To apply synchrotron chemical imaging for analyzing impurity signatures in nuclear fuel pellets.
• To differentiate between contrasting UO2 fuel fabrication techniques using impurity analysis.

Main Methods:

• Hard X-ray synchrotron chemical imaging (X-ray absorption near-edge structure and X-ray fluorescence).
• Analysis of impurity spatial distributions, chemical compositions, and morphological/molecular characteristics.

Main Results:

• Detected differences in UO2 stoichiometry and identified Al, Fe, Ni, W, and Zr impurities.
• Differentiated pellet synthesis and processing methods based on impurity populations and forms (metallic/oxide).
• Suggested multiple impurity sources, including fabrication and feedstock.

Conclusions:

• Synchrotron techniques effectively integrate multi-scale signatures for nuclear forensics.
• This approach can detect and differentiate contrasting UO2 fuel fabrication techniques.
• Impurity signature analysis provides significant advancements in nuclear material forensic capabilities.