Comparative modeling of an in situ diffusion experiment in granite at the Grimsel Test Site.

摘要: An in situ diffusion experiment was performed at the Grimsel Test Site (Switzerland). Several tracers (H-3 as HTO, Na-22(+), Cs-134(+), I-131(-) with stable I- carrier) were continuously circulated through a packed-off borehole and decrease tracer concentrations liquid phase monitored for period of about 2 years. Subsequently, section overcored profiles rock analyzed (H-3, Cs-134(+)) H-3 Na-22(+) showed similar activity circulation system (slightly larger drop H-3). The Cs-134(+) much more pronounced. Transport distances 20 cm H-3, 10 1 Cs-134(+). dataset (except because complete decay end experiment) different diffusion-sorption models by teams (IDAEA-CSIC, UJV-Rez, JAEA) using codes, goal obtaining effective coefficients (D-e) porosity (phi) or capacity (alpha) values. From measurements rock, it observed that not possible to recover full (no balance when adding activities fluid system). A Borehole Disturbed Zone (BDZ) had be taken into account fit experimental observations. extension BDZ (1-2 mm) is same magnitude than mean grain size quartz feldspar grains. IDAEA-CSIC UJV-Rez tried directly match results experiment, without forcing any laboratory-based parameter values models. JAEA conducted predictive modeling based on laboratory data their scaling conditions. from codes have been compared, also small-scale experiments. Outstanding issues resolved are need very large factor difference between apparent (D-a) out-leaching tests.