The data analysis of the single well injection-withdraw tracer experiment using the MACRO II

*; Kanazawa, Yasuo*;

JNC TN8400 2001-012, 69 Pages, 2001/04

JNC-TN8400-2001-012.pdf:6.87MB

On understanding the radionuclide transport in natural barrier in radioactive waste isolation research, the macroscopic dispersion in heterogeneous permeability field in the underground rock is regarded as an important process. Therefore, we have conducted lots of tracer experiments by the MACRO II facility with an artificially constructed heterogeneous permeability field. In order to study the scale dependence of dispersion coefficients in case of laboratory experiments, we placed the flow cell horizontally, and conducted injection-withdraw tracer experiment with a single well. We have conducted I5 cases experiments. These cases were prepared by changing a position of single well and the injection-withdraw time. At each position we have conducted 9 cases and 6 cases experiments. In this report, we evaluated the macroscopic dispersion coefficients by the fitting of analytical solution to breakthrough curve measured by the 15 cases pumping tracer experiment. Consequently, we could evaluate the dispersion coefficients for 12 cases of 15 cases. Then, we discussed the relation between a injection-withdraw flow rate and a property of heterogeneous media and dispersion coefficient. The conclusions obtained from the results of the evaluation are summarized as follows, (1)It was found that the macroscopic dispersion coefficients tend to be increased with increase of the average radius of tracer front spread around a single well. (2)We have conducted any experiments with s single well settled at two positions. In case of that there is low permeability around a single well, we found dispersion coefficients are large. In case of that there is high permeability around a single well, we found dispersion coefficients are small. (3)In three cases that we could not evaluate because of incorrect accuracy of fitting, we have found it possible that there is some points that dispersion coefficients were strikingly small in tracer front.

Discrete Fracture Modelling of the Aspo LPT-2,Large Scale Pumping and Tracer Test

PNC TN8410 94-269, 77 Pages, 1994/07

PNC-TN8410-94-269.pdf:2.13MB

This report describes FracMan discrete fracture flow transport modelling of the LPT-2, large-scale pumping and tracer test, at the SKB Aspo Hard Rock Laboratory. This work was carried out under the international cooperation program of the AsPo Task Force on Groundwater Flow and Transport of Solutes. The scale of simulation was approximately a one-kilometer cube. The discrete fracture model contains two major fracture types - fracture zones, which were located deterministically according to SKB's conceptual model of the Aspo site, and fractures outside the fracture zones which were generated stochastically. The geometric and hydraulic properties of each group were developed from the SKB modeling database, except for non-zone fracture length which we developed from our own mapping of surface outcrops. Two separate models were prepared for the March and September, 1993, task force meetings respectively. The March model represented the fracture zones as 10-m thick Planar regions containing populations of 30-m radius discrete fractures. The September model represented the fracture zones as single planes, which were discretized on a 20- to 30-m scale for a geostatistical assignment of properties. The September model also included conditioning of the properties to the borehole data. Both models generally reproduce the drawdown and transient pressure interference responses of the experiment. The tracer breakthroughs were simulated using only the September model. Calibration runs of the transport model varied the mean transport aperture, aperture variance, and aperture correlation length. The results of this modelling exercise show that a discrete fracture model can be applied at kilometer scales if the flow is dominated by a small portion of fracture population. The results also show that the SKB conceptual model is consistent with the field measurements.

Modeling of solutes transport at the Horonobe URL, 3; In-situ tracer tests in the rock matrix

Ito, Tsuyoshi*; Tachi, Yukio; Nemoto, Kazuaki*; Sato, Tomofumi*; Takeda, Masaki; Ono, Hirokazu

no journal, , 

To validate the mass transfer model in sedimentary rocks, in-situ tracer test in rock matrix was conducted at rock matrix at 350 m deep drift in the Horonobe URL. The modeling results were evaluated to be reasonable by comparing in-situ and laboratory data.

Evaluation of spatial distribution of groundwater in bed rock through the intermediary of fracture

Watanabe, Yusuke; Fukuda, Kenji; Murakami, Hiroaki; Iwatsuki, Teruki; Suzuki, Yohei*

no journal, , 

In this study, microbial incubation experiment was conducted at 300m depth in Mizunami underground research laboratory for the purpose of evaluating the relation between microbial activity and geochemical characteristics in underground environment. In this test, it is necessary to evaluate the microbial activity based on the change in the dissolved component concentration of the groundwater, and it is necessary to grasp the change of the dissolved component due to the exchange of the groundwater in the borehole in advance. Therefore, fluorescent tracer was added to evaluate how the groundwater during the cultivation test spreads into the surrounding rock.