Estimation of Accuracy of the Method of Gamma- Spectrometry for Non-Destructive Control of Gadolinium Content and Uranium Enrichment in Non-Irradiated VVER-type Fuel Pellets

Abstract

The gamma-spectra of the single (UO2-Gd2O3)-pellets were measured on the planar detector HPLeGe. The measurements of Gd content in (UO2-Gd2O3)-pellets were performed by X-ray fluorescence method. The total count rate in the doublet 42,3 and 43,0 keV Kα 1,2-X-rays from Gd was used as a measure of Gd content. In measurements was used241Am as an external radiation source for exciting the doublet 42,3 and 43,0 keV Kα 1,2-X-rays from Gd. In order to obtain the calibration dependence of count rate in doublet 42,3 and 43,0 keV from Gd content in (UO2-Gd2O3)-pellets there were used standard (UO2-Gd2O3)-pellets with the known Gd content, density and enrichment. The estimates of influence of deviations of the density of (UO2-Gd2O3)-pellets and Gd content on total count rate in doublet 42,3 and 43,0 keV were performed. The “pure” gamma-spectra (without employing of external radiation source) were used to obtain the data on uranium enrichment of fuel pellets using multigroup gamma-spectra analysis code (MGAU) and additional information about Gd content. The dependence of from Gd content in (UO2-Gd2O3)-pellets is present (the ratio of count rates for two peaks: Eγ=185,7 keV (the measure of235U) and E=98,43 keV (the measure of235,238U).