The leaching behavior of nuclear wastes embedded in bitumen has been extensively studied for a decade by many teams of researchers. The main conclusion is that both water uptake and salts release obey to a diffusive regime. The most preponderant parameters of the Bituminized Waste Products (BWPs) leaching are, on the one hand, the nature and the content of the salts that are embedded in the bitumen, and on the other hand, the microstructure of bitumen and the external constraint applied to this confining material.
The numerical code COLONBO, designed by the CEA, allows to predict the behavior of the BWPs leaching in the case of salts embedded in soft bitumen and in free swelling conditions (no mechanical constraints during the leaching). This paper intends to achieve two goals: (i) to propose an analytical resolution of the system of equations implemented in COLONBO by using accurate simplification. The validation of this approach relies on the comparison with the predicted solutions of COLONBO and, when available, with the experimental results. (ii) To extend this simplified modeling to the case of restricted swelling conditions. The point is that the validation of this approach would allow us to propose a unified system of equations, allowing to simulate the BWPs leaching in whatever conditions and improving consequently the field of validity of the predictions for the behavior of bituminized waste products.