Relationship between dissolution rate of uranium dioxide pellets in nitric acid solutions and their porosity

Dissolution of uranium dioxide pellets /10 mmø×11 mm/ in nitric acid was studied. A dependence of the initial dissolution rate on acid concentration and temperature was observed. The effective surface area of the pellet was measured during the dissolution process, and compared with its apparent surface area. The experimental dissolution curve was in good agreement with the curve obtained by simulations assuming that the dissolution rate depends on the effective surface area.