Microscopy and Microanalysis



SPECIAL SECTION: MICROANALYSIS OF MATERIALS TODAY

Characterization of Uranium Particles Produced by Hydrolysis of UF6 Using SEM and SIMS


Ruth  Kips  a1 a2 c1 , Ann  Leenaers  a3 , Gabriele  Tamborini  a4 , Maria  Betti  a4 , Sven  Van den Berghe  a3 , Roger  Wellum  a1 and Philip  Taylor  a1
a1 European Commission, General Directorate Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, 2440 Geel, Belgium
a2 University of Antwerp, Department of Chemistry, Universiteitsplein 1, 2610 Antwerpen, Belgium
a3 Studie Centrum voor Kernenergie•Centre d'Etude de l'énergie Nucléaire (SCK•CEN), Nuclear Materials Science Institute, Laboratory for High and Medium Activity, Boeretang 200, 2400 Mol, Belgium
a4 European Commission, General Directorate Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe, Germany

Article author query
kips r   [PubMed][Google Scholar] 
leenaers a   [PubMed][Google Scholar] 
tamborini g   [PubMed][Google Scholar] 
betti m   [PubMed][Google Scholar] 
van den berghe s   [PubMed][Google Scholar] 
wellum r   [PubMed][Google Scholar] 
taylor p   [PubMed][Google Scholar] 

Abstract

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.

(Received August 4 2006)
(Accepted February 28 2007)


Key Words: uranium particles; uranium hexafluoride; nuclear safeguards; scanning electron microscopy; secondary ion mass spectrometry.

Correspondence:
c1 Corresponding author. E-mail: ruth.kips@ec.europa.eu