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Environmental sampling (ES) is a powerful technique used by safeguards inspectors of the International Atomic Energy Agency and the European Safeguards Office for the detection of undeclared nuclear activities. Since its implementation in the 1990s, ES has proven to be very sensitive and effective. Considering the consequences, the measurements should be carried out under a quality management programme. At the Institute for Reference Materials and Measurements, a new production method is under development for the preparation of reference uranium particles from well-certified UF6, allowing uranium particles with certified isotopic abundances to be prepared that are representative of those found in uranium enrichment facilities. Using an aerosol deposition chamber designed and built for the purpose, particles are formed by the hydrolysis of UF6 and their morphology and (isotopic) composition measured using SEM-EDX and SIMS. The SEM measurements show that by varying the relative humidity of the air in the reaction chamber, the morphology of the particles can be changed. By making a distribution map of the chemical composition of the particles, the relationship between fluorine and uranium as main constituents of the particle could be established. The presence of fluorine is a valuable indicator for the occurrence of nondeclared enrichment activities.

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Glancing-incidence x-rays provide a wealth of possibilities for the analysis of thin layers and multilayers. This paper discusses reflectometry under both specular and non-specular conditions, and also the combination with angle-dependent x-ray fluorescence. From these measurements information can be obtained on layer thickness, interface quality and compositional depth profile. First the historical development of glancing-incidence x-ray analysis is sketched. Then the physical principles of the interaction of glancing-incidence x-rays with samples which may contain rough interfaces are discussed. The equipment, which allows for both x-ray fluorescence and reflectivity measurements, is also described. The possibilities are illustrated with a number of examples from the literature.