Quantitative WDS Analysis to Determine Pu Homogeneity in CANDU MOX Fuel

Abstract

As part of AECL's mixed-oxide (MOX) fuel development program, a quantitative X-ray wavelength dispersive spectrometric (WDS) analysis was conducted to determine plutonium homogeneity in as-fabricated MOX fuel, using a shielded analytical scanning electron microscope. This paper describes the technique and some results of the analysis.

The as-fabricated fuel exhibited a duplex microstructure: a matrix with randomly distributed plutonium-rich particles. The particle size ranged from 10 to 30 μm. To conduct the WDS analysis, PuO₂ and UO₂ standards were used; plutonium M_β and uranium M_α lines were monitored. Point analysis with a 2-μm interval was conducted diametrally across the particles to obtain uranium and plutonium distribution profiles. The profiles all exhibited a similar shape; a compositional transition band was observed around each particle, indicating the occurrence of plutonium and uranium interdiffusion. Uncertainty and consistency of the determinations were examined, and the results are satisfactory.