Studies of the Preparation of Thoria and Thoria-Urania Microspheres Using an Internal Gelation Process

Fabrication of (Th,U)O2 pellets containing 3 mol% of uranium by gel pelletisation technique

“…For a given metal ion concentration, the formed gel changed from soft opaque to hard transparent appearance with the increase in molar ratio R. Similar results were re- ported by several workers for urania [9][10][11][12] and by Kumar et al [6] for ThO 2 microspheres preparation by internal gelation process. Lloyd et al [13] studied these aspects for urania and attributed this effect to crystal habit and crystallization behaviour of urania.…”

“…This is mainly due to large difference in their gelation temperature. The gelation temperature for obtaining hard and opaque gel, in the case of thoria is 60-70°C [6] compared to 25-50°C for urania [12]. This can be explained on the basis of the following major differences in these two systems.…”

“…Several batches of 500 ml broth volumes were prepared. The compositions of the feed broth were selected from the gelation field diagram constructed by Kumar et al [6]. terized with respect to physical appearance and leaching behaviour during ammonia washing.…”

Fabrication of dense (Th,U)O2 pellets through microspheres impregnation technique

“…For each of the metal ion concentrations from 0.8 to 1.25 M, spherical gel particles were obtained. Kumar et al [17] reported that the nature of the gel varied from soft opaque gel particles to hard opaque ones and at last to hard translucent particles, when R was increased in their study to prepare ThO 2 microspheres using Th(NO 3 ) 4 solution denitrated with formaldehyde and un-boiled HMTA, urea solution. They further reported that the minimum metal ion concentration required for obtaining gel particles was 1.0 M. Subsequently, Pai et al [5] also reported similar results with partially neutralized Th(NO 3 ) 4 solution by ammonia and un-boiled HMTA, urea solution.…”

Preparation of (U0.55Th0.45)O2Microspheres by Sol-Gel Process

“…They sinter at lower temperatures. 4. The fuel solid solutions prepared by these routes exhibit good micro-homogeneity.…”