Assessment of uranium inhomogeneity and isotope imaging of uranium samples for nuclear forensics

Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) was used to study the heterogeneity of solid uranium materials. By the spatial measurement the degree of isotopic homogeneity at micron-level could be assessed in nuclear samples for nuclear safeguards and forensics. LA-MC-ICP-MS was applied for two UO2 pellets distributed in the 5th Collaborative Materials Exercise (CMX-5) organized by the Nuclear Forensics International Technical Working Group (ITWG). The two materials in question have very similar 235U enrichment (around 1%), but very different 235U isotopic heterogeneity. Although both UO2 pellets were prepared from identical source materials (mixture of depleted 0.3% and low-enriched 4.5% 235U), their different production routes resulted in differences at micron-scale. By the spatially resolved measurement the number of constituting components (feed materials) with different uranium enrichment and their n(234U)/n(238U) and n(235U)/n(238U) isotope ratios could be determined. Imaging can help assess the lateral dimensions of the individual components (grains) and may indicate a certain production route. This information on the homogeneity, the possible production process and isotopic composition of the constituents are highly valuable in nuclear forensics investigations for determining the origin of an unknown nuclear material.

VARGA Zsolt;  WALLENIUS Maria;  NICHOLL Adrian;  MAYER Klaus; 

2020-07-31

PERGAMON-ELSEVIER SCIENCE LTD

JRC120535

0584-8547 (online),   

https://www.sciencedirect.com/science/article/pii/S0584854720302366?via%3Dihub,    https://publications.jrc.ec.europa.eu/repository/handle/JRC120535,   

10.1016/j.sab.2020.105920 (online),