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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.
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; 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; 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; 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; 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.
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.
