Year
2002
Abstract
Gamma spectrometry of uranium samples appears to be a promising tool for the IAEA inspectorate to verify the absence of undeclared production at uranium mines and mills during complementary access under Article 4.a.(i) of the Model Additional Protocol (INFCIRC/540). Forty-five samples of uranium ores, intermediate and final products were collected at the 3 Australian mines: Ranger, Olympic Dam and Beverley. Twenty samples were measured directly in the field immediately after sampling with a portable gamma spectrometer. The Th-234 /Th-230 and Ra-226 /U-235 activity ratios were measured by HRGS without efficiency calibration by the use of appropriate gamma lines having similar energies. The first ratio is used for age estimation and the second one characterises the type of the material analysed - non-disturbed ore, tails or product. The preliminary results show that HRGS measurements provide reliable estimates of uranium concentration, as well as help to distinguish ore, tails and product. The age of the products and tails can be estimated within a months after ore processing. The paper presents measurement and data evaluation results.