Application of EPMA to the problem of fission gas release from nuclear fuel

At the Institute for Transuranium Elements electron probe microanalysis is being used to measure the local concentration and radial distribution of fission gas xenon in the fuel lattice and in small intragranular bubbles. The success of the technique lies in the use of a high electron acceleration potential and a high beam current, derivation of the X-ray intensity for pure, solid xenon by interpolation of the intensities from a series of elements on each side of xenon in the Periodic Table, and the development of a correction procedure for the effect of gas bubble size and distribution on the emitted X-ray intensity. The technique does not measure the concentration of xenon trapped in large bubbles and pores on the grain boundaries. To overcome this deficiency X-ray fluorescence analysis has been used in conjunction with electron probe microanalysis.