Year
2010
Abstract
Gamma-spectrometric methods to determine composition of fissile isotope U-235 in uranium materials are under development at National Science Center Kharkov Institute of Physics and Technology (NSC KIPT) in compliance with requirements of the State system of account and control (SSAC). The institute has a wide spectrum of uranium-containing materials of different enrichment and it is required to develop a number of methods that could be useful in solution of tasks of nuclear power industry of Ukraine, in particular, to measure characteristics of nuclear fuel, identification of radioactive wastes, etc. Experimental studies have been carried out for metrological certification of the developing methods in order to determine enrichment of standard samples (CRM 146, SRM 969) as well as of uranium-containing materials in different physical forms. Coaxial and planar semiconductor detectors based on Ge of high purity were used while carrying out these measurements, as well as programs to process gamma-spectra MGAU (LLNL, USA) and FRAM (LANL, USA). It is shown that the methods which are under the development on the basis of the available analytical equipment and software and hardware means of processing allow the measurement of enrichment of uranium-containing materials (including U and UO2) using non-destructive method with error not less than 2%. This presentation studies the notion of “uncertainty” of measurements that is present in the documents of the State Nuclear Regulation Committee of Ukraine. Comparison of results of experimental data processing using the “uncertainty” and “error” method of measurements have been performed. It is clear that for some uranium-containing samples the result of measurements obtained with rather low error, nevertheless, could have uncertainty that exceeds 2% considerably. This presentation points out that it is necessary to use notions of “uncertainty” and “error” while assessing the quality of measurements.