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-ray detectionInoshita, Shinya*; Suzuki, Shogo*; Okada, Yukiko*; Kato, Masahiko*; Hirai, Shoji*; Kimura, Atsushi; Hatsukawa, Yuichi; Toh, Yosuke; Koizumi, Mitsuo; Oshima, Masumi
Tetsu To Hagane, 94(9), p.345 - 350, 2008/09
"Tatara" is Japanese original steel making method. Steel made by "Tatara" is famous as low alloy and suited to "Kaji" process. By authors' study, it turned out that we could estimate the source region of raw material of Tatara by As and Sb concentration ratio in Tatara sample. But the concentration of these element in Tatara sample is very low (ppm or sub-ppm order), therefore, quantitative analysis is very difficult. In this study, we adopted Neutron Activation Analysis combined with Multiple -ray detection (NAAMG) to analyze As and Sb in "Tatara" sample (iron lump and sand iron, slag). NAAMG is high sensitive and non-destructive analysis method which combined NAA (Neutron Activation Analysis) and multiple -ray detectors. Each "Tatara" sample (iron lump, sand iron, slag) were irradiated for 1-2 h (for As measurement), 8-17 h (for Sb measurement) in JRR-3M HR irradiation field (thermal neutron flux was about 9.0
10
n/m 
s
). And cooling time was 4-5 days (As), and 19-36 days (Sb). Coincidence -rays were measured by -ray detector array, GEMINI-II. Counting time was 1-8 hours (As), and 2-41 hours (Sb). Quantification was made by comparison method. As a result of measurement, the concentration of As and Sb in all "Tatara" samples were determined by NAAMG and these were sub-ppm order. Lower Limit of Determination (LLD) of As was 0.1 ppm order and Sb is 0.01ppm order. From the above-mentioned point, the effectiveness of NAAMG to analyze trace element in "Tatara" sample was confirmed.
Kawamura, Makoto; Jia, H.*; Koizumi, Yukiko*; Niwa, Masakazu; Umeda, Koji*
no journal, ,
Volcanic dykes were extracted from a geological map of 1 / 200,000 and location information was converted into GIS data. The number of volcanic dykes extracted was 593 in the Chugoku region, 228 in the Shikoku region, and 308 in the Oshima Peninsula in the southern part of Hokkaido. More than half of the major axis lengths of rock veins are less than 1km, and more than 80% including those less than 2km. Some rock veins exceed 10km, but they are distributed around the cauldron. The distribution of quaternary volcanic dykes exposed on the surface of the three areas is limited to within 10km from the quaternary volcano. Regarding the relationship between the quaternary volcano and the dykes older than the quaternary period, it is considered that the relationship is low as a result of examining the relationship such as the distance and the extension direction of the dykes. We also examined the relationship between Neogene-Tertiary volcanic activity and the dykes distributed in the surrounding area. In the case of Ishizuchi Cauldron, it was shown that the maximum distance from the related rock veins was about 5km. On the other hand, it was found that the dykes of the Kibi Plateau in the Chugoku region are distributed within a range of approximately 15km from the central point of activity. Comprehensive information gathering as described above and statistical examination using them are useful as basic information for investigating and evaluating the range of influence of magma in the geological disposal.
Kawamura, Makoto; Nishiyama, Nariaki; Komatsu, Tetsuya; Jia, H.*; Kageyama, Soichiro*; Koizumi, Yukiko*; Nakanishi, Toshimichi*
no journal, ,
In geological disposal projects and safety regulations for high-level radioactive waste, one of the challenges in surveying and evaluating technology related to uplift and erosion, which is important in site selection and safety assessment of geological disposal, is that in the distant future, topography mainly due to river undercuts will occur. It is necessary to be able to quantitatively evaluate the changes and effects that these changes have on the underground geological environment. Among the geological environmental conditions, changes in groundwater recharge areas and outflow areas are important when building performance evaluation models because they can change the flow direction of surface water infiltration into the ground or groundwater outflow to the surface. This time, we selected rivers with different basin areas and uplift rates, and divided the basins into which we would like to measure the topographic features of each river. We measured 10 items of topographic features for the divided watersheds, and created data on trends in changes in topographic features. In addition, we calculated the "runoff index," which is defined as an index that expresses the ease or difficulty of surface runoff flow, and estimated and visualized the influence of river undercuts on topography. Regarding the rivers studied, the divided basins with high principal component scores of "basin average erosion height," "topographical complexity," and "basin relief number," which are indicators of topographical steepness among topographical features, were medium to high. There was a tendency to concentrate in the upper reaches. It was shown that the runoff index tends to be high in areas where high-elevation catchments are concentrated. Although this tendency is consistent with general understanding, I think it is significant that we were able to present this area classification quantitatively rather than qualitatively.
Nishiyama, Nariaki; Kawamura, Makoto; Komatsu, Tetsuya; Jia, H.*; Koizumi, Yukiko*; Nakanishi, Toshimichi*; Umeda, Koji*
no journal, ,
One of the key issues in the investigation and assessment technologies related to uplift and denudation, which are important for site selection and safety assessment of geological disposal of HLW, is the need to enable quantitative assessment of changes and their effects on the surface topography and geological environment in the distant future due to river cutting. In the study of performance assessment models that take into account landform development, simulations are based on information on river cross-section geometry, however information on river cross-section geometry has not been well organized. Against this background, the authors have obtained river cross-section data mainly for major rivers in Japan by GIS topographic analysis using the GSI's 10 m DEM (Kawamura et al., 2023). In this study, we expanded the data by increasing the number of target rivers and organized the data. In this presentation, we report the results of the comparison of cross-section profiles for each river, and the results of the grouping of specific height change from downstream to upstream and horizontal distance from riverbed to peak elevation by uplift rate, geology, climatic conditions, and other factors. These results will contribute to the validation of future projections such as landform development simulations and performance assessment models.
Kawamura, Makoto; Nishiyama, Nariaki; Jia, H.*; Ishikawa, Taiki*; Koizumi, Yukiko*
no journal, ,
Among the natural phenomena that may have a significant impact on a geological disposal system, it is necessary to model the extent of impacts related to the loss of containment function, such as fracture zones and damage zones around faults, when new faults occur or geological faults are reactivated, in relation to earthquakes and fault activity. When a fault is formed, complex situations are expected in which the fault becomes a new migration path for groundwater, and it is thought that the amount of displacement and the properties of the fault surface are not homogeneous even on the same fault. However, in the models used in the safety assessment studies to date, the amount of displacement of a fault and the properties of the fault surface have been treated as homogeneous, and a model that reflects this heterogeneity has not yet been presented. In the field of geological engineering, technology has been established to grasp the development of rock fractures based on microearthquakes, and it is believed that the area where aftershocks, including microearthquakes, occur after an earthquake suggests the extent of the damage zone. In addition, the fault model of the "Analysis results of earthquake source process, etc." published by the JMA may be a useful reference for estimating the amount of fault displacement and the properties of the fault plane. Therefore, we conducted a trial effort to collect and organize data on earthquakes and faults, with the aim of reflecting this in the evaluation model. As a result, we were able to express the range and shape of the aftershock area according to the scale of fault activity as 3D information, which can be used as a reference when modeling. In addition, although it is not directly related to the heterogeneity of physical properties such as permeability of the fault plane, we were able to collect and organize information that can be used as a reference.
Niizato, Tadafumi; Sasaki, Keiichi*; Koizumi, Yukiko*; Jia, H.*; Okino, Ryo*
no journal, ,
In this paper, we present the temporal changes of Cs-137 depth distributions in forest floor of the evergreen coniferous forests in Fukushima by applying of a cluster analysis to the Cs-137 depth distribution in the forest floor obtained annually about 70-80 points from 2014 to 2020. The results show the temporal changes in the Cs-137 amount decreasing in the litter layer and increasing in the soil layer as a general trend. However, the progress of the Cs migration from the litter to soil layer is distinctly different in each investigation site.
Kawamura, Makoto; Nishiyama, Nariaki; Jia, H.*; Koizumi, Yukiko*; Niwa, Masakazu; Umeda, Koji*
no journal, ,
Volcanic dykes were extracted from a geological map of 1/200,000, and location information was converted into GIS data. More than half of the major axis lengths of rock veins are less than 1 km, the distribution of quaternary volcanic dykes exposed on the surface is limited to within 10 km from the quaternary volcano. Regarding the relationship between the quaternary volcano and the dykes older than the quaternary period, it is considered that the relationship is low as a result of examining the relationship such as the distance and the extension direction of the dykes. We also examined the relationship between Neogene-Tertiary volcanic activity and the dykes distributed in the surrounding area. In the case of Ishizuchi Cauldron, it was shown that the maximum distance from the related rock veins was about 5 km. On the other hand, it was found that the dykes of the Kibi Plateau in the Chugoku region are distributed within a range of approximately 15 km from the central point of activity. Comprehensive information gathering as described above and statistical examination using them are useful as basic information for investigating and evaluating the range of influence of magma in the geological disposal.
Kawamura, Makoto; Nishiyama, Nariaki; Jia, H.*; Koizumi, Yukiko*; Umeda, Koji*; Nakanishi, Toshimichi*
no journal, ,
The topography around the river is flat with wide plains near the river mouth, but deep valleys are formed upstream. These differences in topography reflect the relationship between the hardness of the ground, the rate of uplift, and the erosive force of rivers that carve the ground. In this presentation, we will use the topography around the Abe River and Oi River in Shizuoka Prefecture as an example, and introduce a research example in which cross-sectional data of rivers from the coast to the upper reaches are analyzed. The examples introduced in this article will provide clues to the process by which Shizuoka Prefecture's alluvial fan-like coastal plains and upstream relief are formed by uplift of the ground and erosion by rivers.
Nishiyama, Nariaki; Kawamura, Makoto; Jia, H.*; Koizumi, Yukiko*
no journal, ,
In the geological disposal project and safety regulations for HLW, one of the challenges in the investigation and evaluation technology for volcanic and igneous activity, which is important for site selection and safety assessment of geological disposal, is the sophistication of technology to grasp the range of influence of magma. We therefore focused on the geological maps published by the AIST, extracted "dykes" from the maps, and attempted to evaluate their relationship with Quaternary volcanoes. The information collection target was a 1:200,000 geological map, covering the Chugoku and Shikoku regions and the Hokuriku, Chubu and Kinki regions. The data extraction process involved digitally tracing the distribution of dikes using GIS software and organizing this as GIS data, after which data such as location, size and direction were extracted and organized on a spreadsheet software. There are also ancient calderas and cauldrons, and their locations were converted into a GIS based on literature information, and the distances between them and the dikes were also digitized. Comprehensive collection of such dike information and its use in statistical analysis is believed to be useful as basic information for investigating and evaluating the extent of magma's influence in disposal projects.
Kawamura, Makoto*; Nishiyama, Nariaki; Jia, H.*; Koizumi, Yukiko*; Ishikawa, Taiki*; Umeda, Koji*
no journal, ,
As part of its research and development into geological disposal technology for high-level radioactive waste, the Toki Geochronological Institute is conducting fundamental research into the long-term stability of the geological environment. In developing uplift and erosion survey and evaluation techniques, the research and development is focused on the development of uplift and erosion evaluation methods using thermochronology and geothermobarometry, the advancement of uplift and erosion rate estimation techniques based on multi-dating of emergent landforms, and the advancement of topographic analysis and comprehensive survey techniques to be reflected in modeling of long-term changes in the geological environment. This report will introduce the current status of the advancement of topographic analysis and comprehensive survey techniques to be reflected in modeling of long-term changes in the geological environment as an example.
Kawamura, Makoto; Jia, H.*; Koizumi, Yukiko*; Nishiyama, Nariaki; Umeda, Koji*
no journal, ,
Using topographical analysis with GIS using 10 m DEM, we created 2 km river crossing lines on each side of the three rivers, Abegawa, Oigawa and Kumanogawa, starting from the estuary and going straight to the course of the river every 3 km. In addition, the geological information of the river transverse line was extracted. When the cross-sectional lines of the three rivers are displayed together, it can be seen that the river bed rises and the undulations increase as it goes upstream. A comparison of the cross-sectional shapes of the three rivers reveals similar trends, with peaks of undulations on both sides of the rivers in the middle to upper reaches located approximately 500-1,500 m from the center of the river. The relative height between bed and peak also tends to be around 200-600 m. The difference in elevation between the peaks on both sides of the river and the river bed increased in the upstream direction, that is, the depth of the valley to the river bed increased in the upstream direction. When the riverbed slope of the river longitudinal created from the riverbed elevation was taken, an inflection points where the slope trend rose from the upstream area was seen in all three rivers regardless of the geology and geological structure. Although the trend of elevation of the riverbed and increase in undulations from the relatively flat landform near the mouth of the river upstream is pseudo, it suggests a temporal process of landform formation due to uplift and denudation from the flat lowland. This will be information that contributes to verification of the validity of future predictions and performance evaluation models that incorporate topographical changes, such as topographical change simulations.
Kawamura, Makoto; Nishiyama, Nariaki; Komatsu, Tetsuya; Jia, H.*; Koizumi, Yukiko*; Kabasawa, Satsuki; Umeda, Koji*
no journal, ,
In performance assessment of geological disposal of high-level radioactive waste, the impact of long-term changes in the surface environment, including topography caused by uplift and erosion, is important because the assessment period exceeds hundreds of thousands of years. One of the effects of uplift and denudation on the assessment of nuclide migration is the change in the location of groundwater discharge and recharge areas due to changes in topographical relief, such as river denudation, which is expected to affect the biosphere assessment process. As a tool to examine this issue, a "Analytical Tool of Evolution of Topography and Repository Depth" has been developed. On the other hand, it is necessary to verify how realistic the terrain created by this tool is for the performance assessment of the repository. In particular, there are few studies on transverse landforms formed by river cross section. In this report, we attempted a similar topographical analysis using actual and virtual topographical data for rivers, and report the results of a comparison and examination with river cross sections and runoff indexes, which are basic information necessary for performance assessment of disposal sites.
Nishiyama, Nariaki; Kawamura, Makoto; Komatsu, Tetsuya; Jia, H.*; Koizumi, Yukiko*; Kabasawa, Satsuki; Nakanishi, Toshimichi*; Umeda, Koji*
no journal, ,
no abstracts in English
Kawamura, Makoto; Nishiyama, Nariaki; Komatsu, Tetsuya; Jia, H.*; Koizumi, Yukiko*; Kabasawa, Satsuki; Nakanishi, Toshimichi*; Umeda, Koji*
no journal, ,
In geological disposal projects and safety regulations for HLW, one of the challenges in surveying and evaluating technology related to uplift and erosion, which is important in site selection and safety assessment of geological disposal, is that in the distant future, topography mainly due to river undercuts will occur. It is necessary to be able to quantitatively evaluate the changes and effects that these changes have on the underground geological environment. Among the geological environmental conditions, changes in groundwater recharge areas and outflow areas are important when building performance evaluation models because they can change the flow direction of surface water infiltration into the ground or groundwater outflow to the surface. The most reliable way to evaluate recharge and discharge areas is to use actual measured data on precipitation and river flow. However, when dealing with past or future topography, or hypothetical topography generated by simulations of topographical change, actual measurements are not possible, and so technology is required to indirectly estimate the area from topographical information. As one of the research technologies, a method has been developed to measure topographical features using a digital elevation model, calculate runoff volume using statistical analysis techniques, and visualize it as an index. In previous studies, we also attempted to apply this method to three rivers which have different drainage basin areas and uplift rates, and were able to present, to a certain extent quantitatively, results that are consistent with the general understanding that areas where high-altitude divided drainage basins are concentrated are high, meaning that surface water tends to flow more easily. Here, following previous studies, we report an example of applying the same method to a virtual topography created by simulating topographical change, and comparing and examining it with an actual river.
Kawamura, Makoto*; Nishiyama, Nariaki; Jia, H.*; Ishikawa, Taiki*; Koizumi, Yukiko*
no journal, ,
In site selection and safety assessment for geological disposal, dikes observed in the field are important targets for evaluating the extent of the influence of volcanic and igneous activity. Dikes have often been shown on geological maps in previous studies, so it may be possible to understand their distribution to some extent. We extracted "dikes" from the geological maps on a GIS and attempted to organize them by geological era. In this presentation, we will report on the status of data collection and preparation. The data will not only provide basic information for evaluating the relationship with Quaternary volcanoes, but is also expected to be academically useful, such as for understanding volcanic activity that occurred before the Quaternary Period.
Kawamura, Makoto; Jia, H.*; Koizumi, Yukiko*; Niwa, Masakazu; Umeda, Koji*
no journal, ,
One of the issues related to volcanic and igneous activities in the safety assessment of geological disposal of HLW is the sophistication of technology for grasping the range of influence of magma. To address this issue, it is necessary to accumulate data, especially when the dike extends over a radius of 15 km from the center of the Quaternary volcano. However, it is practically difficult to grasp the distribution of the conduits underlying the existing volcanic bodies and the dikes derived from them. In field geological surveys, small outcrops with intrusive dikes may be found even in places away from Quaternary volcanoes. Whether such dikes are associated with nearby Quaternary volcanoes is important in assessing the extent of the dikes. We extracted "dike" from the geological map width published by the AIST, and tried to evaluate its relevance to the surrounding Quaternary volcanoes. As a preliminary study, we used Daisen, a Quaternary volcano in the Chugoku region. The distribution of dikes is digitally traced, GIS data is created and organized on a white map, and then "position (latitude / longitude)", "size (major axis / minor axis, etc.)", "era", "rock type", "dike intrusion stratum name, era" and "nearest volcano name, distance from crater" were extracted. As a result, 151 volcanic dykes were extracted. The dikes associated with Quaternary volcanoes are limited to new Daisen volcanic ejecta (parasitic volcanoes), and their distribution is also limited to the Daisen volcano. All dikes located far from the volcano are determined to have been formed before the Neogene. Some of them are lava, but some are deep-seated rocks such as dolerite and diorite. A relatively large number of pre-Neogene dikes show a lenticular distribution morphology, and the dikes of acid rocks are the main constituents. This suggests that dikes formed deeper than the Quaternary became visible on the surface due to denudation.
Kawamura, Makoto*; Nishiyama, Nariaki; Jia, H.*; Ishikawa, Taiki*; Koizumi, Yukiko*
no journal, ,
One of the challenges in the investigation and evaluation technology for the safety assessment of geological disposal of high-level radioactive waste is the quantitative evaluation of the changes and their impacts on future surface topography and underground geological environment caused by river incision due to uplift and denudation. Changes in the surface topography due to river incision will affect groundwater flow and will also require consideration of the location of the disposal site near the surface. Such studies require information on the cross-sectional shape of rivers, but there is little reference information available compared to the longitudinal sections of rivers, which are often the subject of research. Therefore, we have been collecting cross-sectional shape data, mainly of rivers, by performing topographical analysis using GIS with the 10m DEM. When comparing actual rivers, there was no significant difference in the relative height difference due to differences in the main geology of the riverbed, and a tendency was observed to depend on the uplift rate. When comparing the virtual and real rivers, although there is a difference in resolution between the virtual and real rivers, the data on peak relative height shows a tendency for it to increase with the uplift rate, which is not inconsistent with the trend of the real rivers. However, a tendency for the relative height to be smaller than that of the actual terrain was observed, and a gap was also confirmed between the virtual terrain and the actual terrain.
