Year
2001
Abstract
The Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC), with assistance from the U.S. Department of Energy (DOE) began a program in June 1998 to evaluate environmental sampling capabilities at laboratories in Argentina and Brazil. The program included training in South America and the U.S., as well as an evaluation exercise using swipe samples prepared by the International Atomic Energy Agency (IAEA) with precisely known amounts of uranium isotopic standards. Results from this exercise were reported at the Institute of Nuclear Materials Management (INMM) 41st Annual Meeting [1]. Evaluation of data from that exercise showed that the ABACC laboratories made progress in developing the capability to determine both the quantity and isotopic composition of uranium at levels expected in typical environmental samples. However, in some cases, it was evident that uranium contamination was seriously affecting the results. The results highlighted the importance of contamination control in environmental analyses, where the uranium concentration in the sample is often many times less than found in the ambient environment (i.e., the sample preparation and analysis laboratories). The next stage in evaluating ABACC environmental sampling capabilities involved implementation of stringent contamination-control practices, followed by a quantitative assessment of the uranium blank at each stage of the sample preparation and analysis process. Isotope dilution mass spectrometry (IDMS), using a 233U spike from the New Brunswick Laboratory, was used to measure uranium content. In addition to quantitative blank determinations, ABACC also initiated a new round of measurements on National Institute of Standards & Technology (NIST) Standard Reference Material (SRM) 1547, Peach Leaves, that contained an uncertified uranium concentration of 0.015 mg/g. This SRM effectively simulates an actual environmental sample and provides a challenging test of low-level analysis capabilities.