Controlling features and processes for radionuclide release from unsaturated zone geological repositories
In the long run, nuclear waste packages will fail gradually due to localized and general corrosion and radionuclides will be transported to the accessible environment by ground water. Two main failure scenarios are expected for the waste packages: Flow-through model and bathtub model; in the flow-through model water flows through the waste container, while in the bathtub model water pools inside the waste package. The Department of Energy, in their performance assessment of the proposed repository at Yucca Mountain, excluded the bathtub model from their analysis and assumed the diffusion and advection to be in the same direction in the flow-through model. In this research, a new conceptual model is introduced for radionuclide release from a flow-through category failed waste container. Due to the residual heat release of the nuclear waste, this model expects a bidirectional transport for radionuclides in the sheltered areas; advection toward the warmest region and diffusion in the opposite direction. As a result, a sequestration process is expected for the radionuclides in the sheltered areas, which would delay the radionuclide release and make it gradual. The analysis showed that the sequestration will be more effective at higher rates of heat generation and lower moisture conditions. As for the bathtub model, conditions inside the bathtub category failed waste container are investigated. The analysis showed that temperature stratification is expected in the lower half of the waste package, which would limit oxygen availability and slow the corrosion of the spent nuclear fuel and other waste package components. As a result, the estimated life for all waste package components will be longer and consequently radionuclide release will be delayed.
Environmental Geology|Environmental engineering
Hamdan, Lubna Kamel, "Controlling features and processes for radionuclide release from unsaturated zone geological repositories" (2010). ETD Collection for University of Texas, El Paso. AAI3409155.