Investigation of factors influencing the accuracy of uranium enrichment level determination by multi-analysis method (MGAU)

Statistical characteristics of multi-group analysis technique for isotopic composition determination of uranium samples, realised in the form of portable "U-Pu InSpector" spectrometry system and MGAU V.1.0 code, have been studied with the help of uranium isotopic standard reference materials in the range 0.32 - 4.5 % of 235U and 0.004 - 0.036 % of 234U concentration. The influence of a number of factors that can cause systematic bias of measured values are also studied. Obtained results reveal dependence of measured 235U enrichment level upon isotopic composition of uranium sample and geometry of the measurement. Systematic underestimation of measured 234U content turned out to be of about 23 % in the concentration range. Possible sources of revealed systematic biases are discussed as well as some recommendations for improving of MGAU code are given.