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Simulation of repository gas migration in a bentonite buffer

2013; Volume: 167; Issue: 1 Linguagem: Inglês

10.1680/eacm.12.00018

1755-0785

Philip J. Vardon, Hywel Rhys Thomas, Shakil Masum, Qing Chen, Duncan Nicholson,

Geophysical Methods and Applications

The inventory of high-level radioactive waste in the UK is likely to be disposed of in a geological disposal facility, which will generate gases due to processes such as anoxic metal corrosion and water radiolysis. Such gases have the potential to migrate through the repository system and may be detrimental to the engineered barrier system by damaging the physical fabric of the buffer material through the build-up of pressure. An investigation into the migration of gases and the ranges of gas pressures expected in such a repository is presented. A model of gas transport is presented to simulate the transport of gases in conjunction with coupled thermo-hydro-chemical-mechanical processes. This model includes a boundary condition linking the corrosion behaviour to gas generation and water supply. A realistic range of gas generation rates has been established from available data alongside realistic ranges of material properties of a bentonite buffer. Numerical simulations were then undertaken for a range of realistic scenarios considering the corrosion processes and buffer properties. It was found that in all realistic cases, including realistic maxima and minima considered, the risk of pneumatic fracture was negligible.