Modeling of Tritium Annual Flux from Concrete Rubble Buried in the Slit Trenches at the Savannah River Site

Some of the concrete rubble generated from the demolition and destruction of some facilities at the U.S. Department of Energy Savannah River Site contains tritium. The tritium-bearing rubble will be disposed in the E-Area slit trenches. In the past, it was assumed for Performance Assessment (risk) modeling that tritium leached from concrete as if the tritium existed entirely on the concrete surfaces. Although conservative (i.e., overestimates risk associated with the groundwater pathway), this assumption does not account for the slow diffusion of tritium from the inside to the outside of the concrete rubble. The objective of this modeling study was to include the diffusion process in tritium annual flux calculations for use in future Special Analyses or Performance Assessments involving the concrete rubble. This paper discusses the general modeling approach and presents the study results