Immobilisation of actinides in phosphate matrices

In the field of the immobilisation of high-activity-level and long-life radwaste (HAVL) for a deep underground repository, several phosphate matrices were already proposed as good candidates to delay the release of actinides in the near-field of such disposal. Among them, thorium phosphate-diphosphate (TPD), monazites/brabantites, britholites, and TPD/monazite composites were extensively studied. The synthesis of samples doped with actinides (Th, U...) through wet and dry chemistry methods then their complete characterisation are reported. Their chemical durability is also examined. These materials appear as promising matrices to immobilise tetravalent and/or trivalent actinides. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.