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Effects of silica redistribution on performance of high-level nuclear waste repositories in saturated geologic formations

Conference ·
OSTI ID:5216654

Evaluation of the thermohydrological conditions near high-level waste packages is needed for the design of the waste canister and for overall repository design and performance assessment. Most available studies in this area have assumed that the hydrologic properties of the host rock do not change in response to the thermal, mechanical or chemical effects caused by waste emplacement. However, the ramifications of this simplifying assumption have not been substantiated. We have studied dissolution and precipitation of silica in thermally driven flow systems, including changes in formation porosity and permeability. Using numerical simulation, we compare predictions of thermohydrological conditions with and without inclusion of silica redistribution effects. Two cases were studied, namely, a canister-scale problem, a repository-wide thermal convection problem, and different pore models were employed for the permeable medium (fractures with uniform or non-uniform cross sections). We find that silica redistribution generally has insignificant effects on host rock and canister temperatures, pore pressures, or flow velocites.

Research Organization:
Lawrence Berkeley Lab., CA (USA). Earth Sciences Div.
DOE Contract Number:
AC03-76SF00098
OSTI ID:
5216654
Report Number(s):
LBL-20479; CONF-850981-8; ON: TI87000125
Country of Publication:
United States
Language:
English