Determination of Fission Products in Irradiated Fuel by X-Ray Fluorescence

摘要

X-ray fluorescence i s a well e s t a b l i s h e d analytical tool for measuring elemental composition of fairly large (~ 5 cm2) "cold" samples. A version of t h i s technique has been developed for a n a l y s i s of radial d i s t r i b u t i o n of f i s s i o n products Xe, Cs and Ba in irradiated U02 fuel samples. About 0.1 mm thin s l i c e s of fuel p e l l e t s (full cross sections) are irradiated by 50 keV X-rays. The i n t e n s i t y of the Xe (Cs, Ba) Ko fluorescence radiation generated i s measured by means of a Ge detector f i t t ed with a collimator. The s l i t i s 0.5 mm wide in the scanning d i rection and 2 mm long. The measured Xe Ko x-ray i n t e n s i t i e s are converted to absolute concentrations by comparing to the intens i t y from a Xe gas standard. In the case of Cs and Ba s o l id standards may be used. The X-ray fluorescence analysis i s compared to other techniques used to obtain radial f i s s i o n product profiles, i t i s shown how a combination of X-ray fluorescence and electron probe micro a n a l y s i s i s able to reveal the amount of Xe in the grain boundary porosities.