  The optimization of the microstructure of the UCx target is a key point since
many years in the field of ISOL method. The ultimate goal is to facilitate the
release of the fission products, especially those with short half-lives.
Fourteen UCx samples were synthetized from different uranium and carbon sources
using three mixing protocols. All carburized samples were systematically
characterized in terms of nature and proportion phases, grain and aggregate
size, open and close porosity proportion and open pore size distribution. Our
results were analysed using a multivariate statistical approach in order to
remove any subjective bias. Strong correlations between the physicochemical
characteristics of the samples as well as the impact of the synthesis process
have been highlighted. In particular, using carbon nanotubes as carbon source
combined with a new method of mixing is the key parameter to limit the
sintering and to obtain samples with small grains and a high porosity well
distributed over small pores. Moreover the microstructure obtained proved to be
stable at high temperature.
