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Okumura, Masahiko; Kerisit, S.*; Bourg, I. C.*; Lammers, L. N.*; Ikeda, Takashi*; Sassi, M.*; Rosso, K. M.*; Machida, Masahiko
Journal of Environmental Radioactivity, 189, p.135 - 145, 2018/09
Times Cited Count：51 Percentile：87.2(Environmental Sciences)no abstracts in English
Doughty, C.*; Tsang, C.-F.*; Yabuuchi, Satoshi; Kunimaru, Takanori
Journal of Hydrology, 482, p.1 - 13, 2013/03
Times Cited Count：16 Percentile：51.79(Medical Informatics)To improve the field method to provide heterogenety data for modeling of solute transport in complex fractured rock, the analysis of the flowing fluid electric conductivity(FFEC) logging was examined. FFEC logging was conducted in the pilot borehole in fractured sedimentary rock in Japan as part of the Horonobe Underground Research Laboratory Project. FFEC logs were collected under unpumped conditions and at two different pumping rates, nominally 8L/min and 16L/min. Though the data have a number of complications, the analysis was successful to identify 17 hydraulically conducting fractures, and to estimate their hydraulic transimissivities, inherent pressure heads and salinities (in terms of fluid electric conductivities). The results are confirmed in comparison with hydraulic packer tests and hydrochemical data.
Doughty, C.*; Tsang, C.-F.*; Hatanaka, Koichiro; Yabuuchi, Satoshi; Kurikami, Hiroshi
Water Resources Research, 44(8), p.W08403_1 - W08403_11, 2008/08
Times Cited Count：17 Percentile：44.06(Environmental Sciences)The flowing fluid electric conductivity (FFEC) logging method is an efficient way to provide information on the depths, salinities, and inflow strengths of individual conductive features intercepted by a borehole, without the use of specialized probes. The present paper presents the application of the method to two zones within a 1000-m borehole in sedimentary rock, which produced, for each zone, three sets of logs at different pumping rates, each set measured over a period of about one day.
Tsang, C.-F.*; Doughty, C.*; Uchida, Masahiro
Water Resources Research, 44(8), p.W08445_1 - W08445_13, 2008/08
Times Cited Count：7 Percentile：22.21(Environmental Sciences)no abstracts in English
Tsang, C.-F.*; Karasaki, Kenji*
JNC TY8400 2001-006, 224 Pages, 2001/07
JNC-TY8400-2001-006.pdf:6.92MB
None
Tsang, C.-F.*; Karasaki, Kenji*
JNC TY8400 2000-007, 279 Pages, 2000/07
JNC-TY8400-2000-007.pdf:7.62MB
None
Karasaki, Kenji*; Ito, Kazumasa*; Maekawa, Keisuke
no journal, ,
We have modeled laboratory experiments of saltwater intrusion using TOUGH2/EOS7. Matching laboratory and simulation results turned out to be quite challenging partly because of numerical dispersion and partly because the experiments were not very well controlled. In order to understand better the effects of numerical dispersion, we simulated the so-called Henry problem, in which a large dispersion coefficient is assumed, resulting in a wide transition zone between freshwater and saltwater. We imposed a sinusoidal boundary condition to see if a large transition zone can be created without explicitly modeling dispersion. However, for the parameters used we were not able to do so. It is still plausible that a wide transition zone is caused by formation heterogeneity and transient effects. Nonetheless, we question the validity of the use of a large dispersion coefficient where the velocity is very low, or where the flow is in the opposite direction of the concentration gradient.
Maekawa, Keisuke; Karasaki, Kenji*; Ito, Kazumasa*
no journal, ,
As a study to comprehend geological environment, we examined numerical analysis in order to understand the behavior of saltwater intrusion. This is an important study for safety assessment of high level radioactive waste geologic disposal. We made sense a relation between an extent of numerical dispersion and various grid spacing in analytical region. And the analytical code was verified with an experiment under the simple condition.
Maekawa, Keisuke; Karasaki, Kenji*; Takasu, Tamio*
no journal, ,
no abstracts in English
Koike, Masato; Ishino, Masahiko; Sano, Kazuo*; Sasai, Hiroyuki*; Takenaka, Hisataka*; Hatayama, Masatoshi*; Heimann, P. A.*; Gullikson, E. M.*
no journal, ,
no abstracts in English
Maekawa, Keisuke; Karasaki, Kenji*; Takasu, Tamio*
no journal, ,
It is important for safety assessment of high-level radioactive waste geologic disposal to understand groundwater flow in deep underground accurately. In order to understand the behavior of seawater intrusion into freshwater in deep underground, we constructed a laboratory equipment, "Mini-MACRO" (MAss transport Characterization in host ROck). We created several cases of experimental conditions to observe the seawater intrusion behavior into two-layered stratum against various hydraulic gradients and densities of saltwater. We confirmed that the results using this equipment match numerical results under simple heterogeneous condition.
Karasaki, Kenji*; Maekawa, Keisuke
no journal, ,
We have modeled laboratory experiments of saltwater intrusion, similar to the so-called Henry Problem, using TOUGH2/EOS7. In general, the simulation showed good agreement to the experiment including the transient advancement and the final profile of the saltwater wedge that showed little dispersion in a homogeneous case. In a two-layer heterogeneous case, however, the simulation could not reproduce the experiment in one aspect. In the experiment, the fast-moving colored saltwater traveling in the higher permeability layer was observed encroaching into the lower permeability layer below. However, at this writing, we have not been able to reproduce this phenomenon, which could be caused by some instability or heterogeneity within the layers.
Yaita, Tsuyoshi; Suzuki, Shinichi; Kobayashi, Toru; Okamoto, Yoshihiro; Shiwaku, Hideaki; Shuh, D.*; Anders, P.*; Guo, J.*
no journal, ,
no abstracts in English
Shizuma, Toshiyuki; Angell, C.; Hajima, Ryoichi; Ludewigt, B.*; Quiter, B. J.*; Koizumi, Mitsuo
no journal, ,
Quasi-monoenergetic laser Compton scattering photon beam was used for a transmission nuclear resonance fluorescence measurement on Ta-181. The experiment was carried out at Duke University. We used photon beams at energies of 2.28 and 2.75 MeV with energy width of about 4% to irradiate absorber and scattering targets of Ta-181 We measured scattered 
-rays from the scattering target using high-purity Ge detectors. As a result, we found three times more strength than the previously known values. In addition, we observed large branching of 75% at 2.28 MeV and 50% at 2.75 MeV going to excited states from resonances. In this presentation, we will report on the measurement method and the experimental results. We will also talk about the future plan for development of non-destructive assay using mono-energetic laser Compton scattering -ray beam.
Shizuma, Toshiyuki; Angell, C.*; Hajima, Ryoichi; Ludewigt, B.*; Quiter, B. J.*; Koizumi, Mitsuo
no journal, ,
Nuclear resonance transmission -rays through a Pu-239 target were measured, as a part of a development project of nuclear material non-destructive detection and assay using quasi-monoenergetic laser Compton scattering (LCS) photon beams. The experiment was carried out at Duke University. We used photon beams at energies of 2.14 with energy width of about 4% to irradiate absorber and scattering targets of Pu-239. We measured scattered rays from the scattering target using high-purity Ge detectors. As a result, we found the average integration cross section of 13 eV barn at excitation energies from 2.12 to 2.19 MeV. The sum of the branching ratio from the excited state to the ground and first excited states are 0.4. This enables us to quantify Pu-239 in a assembly with an error of approximately 3% in four-hour measurement with 10
photon/s beams. In this presentation, we will report on the measurement method and the experimental results. We will also talk about the future plan for development of non-destructive assay using mono-energetic LCS -ray beam. (This development was carried out under "the subsidiary for promotion of strengthening nuclear security or the like of MEXT".)
