Precise non-destructive X-ray fluorescence method for uranium and thorium concentration measurements

A precise non-destructive radioisotope X-ray fluorescence method for uranium and thorium concentration measurements was developed. A beta-emitting 90Sr-90Y source was used for excitation of characteristic X-ray lines. It is proved that the beta-excited X-ray fluorescence method (in spite of the significant bremsstrahlung intensity) has essential advantages for analysis of high concentrations of U and Th, characteristic for nuclear power cycle materials, because of the higher sensitivity of the method. (3% changes of the intensity per 1% change of the concentration.) Portable semiconductor scintillation detectors and multichannel analysers are used for detection of analytical lines. The accuracy achieved by this method is 0.2-0.3% for 15 minutes measurement and 0.1 mCi activity of the source. (author)