Dissolution of UO2 particles by microwave heating
Author: langfeng1 Time: 2017-08-30
Microwave heating is different from conventional heating. Microwaves can penetrate the Teflon vessel and lead to
efficient volumetric heating for the materials of high dielectric loss factor. The nitric acid and UO2
particles are both materials of high dielectric loss factor so that they can extremely absorb microwaves.
Thus, it is possible that the solvents and uranium dioxide can be directly heated by microwave energy,
compared with the conductive heating by conventional energy. The energy must be conducted through the walls
of the vessel containing the solution for conventional heating. The microwave heating is different with
the conventional heating. It can directly heat the uranium dioxide and the nitric acid solution.
In addition, the Teflon vessel is air-proof so the pressure of the vessel is higher for microwave
heating. The pressure will definitely affect the dissolution rate. However, there is not any data
shown in the paper because the microwave oven was not equipped with the pressure detector. Also,
because of the air-proof, the NOX Gas generated with the dissolution of UO2 particles cannot be
removed from the solution. The NOX gas can be dissolved in the nitric solution which makes the
color of the solution brown. The dissolved NOX gas then transformed into nitrous acid which can
accelerate the dissolution reaction process. However, the NOX gas was removed from the vessel
when the experiments carried out in the boiling flask by conventional heating. The dissolution
ratios of UO2 particles were higher when the system was heated by microwave energy. Thus, it
could be a potential alternative for the treatment of the dissolution of UO2 particles in
nitric acid solution by microwave heating.
dissolution ratios of UO2 particles by microwave sintering