Emanation Thermal Analysis—Results from Characterizing Intermediate Steps and Intermediate Products for Urania Spheres

Emanation thermal analysis (ETA) is demonstrated as a tool for the objective characterization of solid phases arising during treatment of the uranyl gel microspheres up to the final UO₂ product. The method is able to monitor very sensible differences in the morphology, surface area, and structure of a solid, as well as their changes when heated. The ETA results for seven samples are discussed and correlated with results from other independent methods (differential thermal analysis, thermogravimetry, thermodilatometry, and density measurements). Various preparation conditions of the internal gelation technique, such as uranium concentration, concentration of gelation additives, the way of leaching, etc., are reflected. The ETA is proposed as a method for simulating thermal processes of UO₂ fuel preparation.