AN INVESTIGATION INTO METHODS FOR THE PARTICLE-SIZE ANALYSIS OF UO₂ POWDER AND THE EFFECT OF BALL-MILLING ON SIZE DISTRIBUTION

Abstract

Techniques for the particle-size analysis of “ceramic-grade” UO₂ in the 4–40 μm size range are assessed, with a view to selecting the most suitable method for analysis of UO₂/PUO₂ mixtures under glove-box conditions.The β-backscatter method is considered to show some advantages over the Coulter counter or optical microscopy and the mean coefficient of variation is ± 1.2% at the 1σ level.

The effects of various forms of pretreatment, e.g., high-speed stirring, manual mixing, and ultrasonic shaking, are examined and discussed with relation to the agglomerative properties of UO₂. Ultrasonic shaking is the most successful form of dispersion and the necessity of standardizing the pretreatment stage is emphasized.

β-backscatter is used to compare particle-size distribution after wet and dry ball-milling. Whilst little difference is observed in the ultimate particle size produced by the two treatments, the effect of agglomeration in dry milling is clearly shown. The increased effectiveness of milling UO₂ powder in a suitable dispersing medium, rather than water, is demonstrated.

Notes

* Manuscript received 30 October 1964.