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JAEA Reports

Survey on the radioactive substance in the coastal areas near Fukushima Prefecture in FY2019 (Contract research)

Misono, Toshiharu; Tsuruta, Tadahiko; Nakanishi, Takahiro; Sanada, Yukihisa; Shiribiki, Takehiko; Miyamoto, Kenji*; Urabe, Yoshimi*

JAEA-Research 2020-008, 166 Pages, 2020/10

JAEA-Research-2020-008.pdf:13.11MB
JAEA-Research-2020-008(errata).pdf:0.92MB

After the accident at TEPCO Fukushima Daiichi Nuclear Power Station (1F), marine monitoring survey on radioactive substances have been conducted with financially supported by the Nuclear Regulatory Agency from FY2019. Results obtain in the project in FY2019 are presented in this report. Based on scientific grounds, the concept necessary for "progress of sea area monitoring" was arranged for the future medium- to long-term investigation of radiocesium concentrations. As basic information of survey frequency revise, a seabed topography and sediment distribution survey was conducted, and an attempt was made to understand the relationship between the seabed topography and the grain size distribution of bottom sediment. A columnar core sample was collected in the coastal area and analyzed for radioactive cesium concentration. In order to understand the dynamics of radioactive cesium contained in suspended matter flowing in from a river, suspended solids was collected using a sediment trap and the concentration of radioactive cesium was measured. We re-analyzed the towed monitoring data that had been implemented since 2013, and tried to improve the accuracy of the radioactive cesium distribution estimation map in the coastal area.

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018) (Translated document)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2020-007, 249 Pages, 2020/10

JAEA-Research-2020-007.pdf:15.83MB

The accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, Japan Atomic Energy Agency (JAEA) has been conducting "Long-term Assessment of Transport of Radioactive Contaminants in the Environment of Fukushima" concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Journal Articles

Radiocesium distribution in the sediments of the Odaka River estuary, Fukushima, Japan

Hagiwara, Hiroki; Nakanishi, Takahiro; Konishi, Hiromi*; Tsuruta, Tadahiko; Misono, Toshiharu; Fujiwara, Kenso; Kitamura, Akihiro

Journal of Environmental Radioactivity, 220-221, p.106294_1 - 106294_9, 2020/09

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Journal Articles

Characterizing the permeability of drillhole core samples of Toki granite, central Japan to identify factors influencing rock-matrix permeability

Kubo, Taiki*; Matsuda, Norihiro*; Kashiwaya, Koki*; Koike, Katsuaki*; Ishibashi, Masayuki; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Sasao, Eiji; Lanyon, G. W.*

Engineering Geology, 259, p.105163_1 - 105163_15, 2019/09

 Times Cited Count:2 Percentile:44.11(Engineering, Geological)

Rock matrix permeability is mainly controlled by microcracks. This study aims to identify the factors influencing the permeability of the Toki granite, central Japan. Permeability of core samples, measured by a gas permeameter, largely increases in the fault and fracture zones. Although a significant correlation is identified between permeability and P-wave velocity, this correlation is enhanced by classifying the samples into two groups by the Mn/Fe concentration ratio. Thus, lithofacies is another control factor for permeability due to the difference in mineral composition. Moreover, permeability shows significant negative and positive correlations with Si and Ca concentrations, respectively. These concentrations are probably affected by dissolution of silicate minerals and calcite generation in the hydrothermal alteration process. Therefore, a combination of hydrothermal alteration and strong faulting are the predominant processes for controlling permeability.

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2019-002, 235 Pages, 2019/08

JAEA-Research-2019-002.pdf:21.04MB

The accident of the Fukushima Daiichi Nuclear Power Station (hereinafter referred to 1F), Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, JAEA has been conducting Long-term Environmental Dynamics Research concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima; As a part of dissemination of evidence-based information

Tsuruta, Tadahiko; Niizato, Tadafumi; Nakanishi, Takahiro; Dohi, Terumi; Nakama, Shigeo; Funaki, Hironori; Misono, Toshiharu; Oyama, Takuya; Kurikami, Hiroshi; Hayashi, Seiji*; et al.

JAEA-Review 2017-018, 86 Pages, 2017/10

JAEA-Review-2017-018.pdf:17.58MB

Since the accidents at Fukushima Daiichi Nuclear Power Plant following the Tohoku Region Pacific Coast Earthquake on March 11th, 2011, Fukushima Environmental Safety Center has carried out research on natural mobilization of radionuclide (especially radiocesium) and future forecast from forest to water system and surrounding residential areas. The report summarizes the latest results that have been accumulated from each study field, of our agency together with the other related research organizations. The contents of the report is to be used as evidence-based information for the QA-styled pages in the website of JAEA Sector of Fukushima Research and Development at the time of next renewal.

Journal Articles

Horizontal and vertical distributions of $$^{137}$$Cs in seabed sediments around the river mouth near Fukushima Daiichi Nuclear Power Plant

Tsuruta, Tadahiko; Harada, Hisaya*; Misono, Toshiharu; Matsuoka, Toshiyuki; Hodotsuka, Yasuyuki*

Journal of Oceanography, 73(5), p.547 - 558, 2017/10

 Times Cited Count:4 Percentile:59.26(Oceanography)

The seafloor topography was divided into flat and terrace seafloors based on their topographical features and seabed sediments were distributed in an area that was half a degree of the entire investigation area. The $$^{137}$$Cs inventory was several tens of kBq/m$$^{2}$$ and the grain sizes (the D50 values) were nearly constant (fine sand) on the flat seafloor. On the terrace seafloor, the $$^{137}$$Cs inventory was larger than that on the flat seafloor, and the grain size varied from silt to coarse sand. The grain size distributions appear to be influenced by the mean shear stress at the seafloor bottom, and a significant factor in the mean shear stress is thought to be the seafloor topography. Distributions of remarkably large $$^{137}$$Cs inventories, more than several thousands of kBq/m$$^{2}$$, are thought to be confined to a small area. Vertical changes in the $$^{137}$$Cs inventories suggested that the $$^{137}$$Cs inventories have significantly decreased in large areas of the shallow sea.

JAEA Reports

A Compartment model of radionuclide migration in environment based on exposure pathways

Kurikami, Hiroshi; Niizato, Tadafumi; Tsuruta, Tadahiko; Kato, Tomoko; Kitamura, Akihiro; Kanno, Mitsuhiro*; Kurosawa, Naohiro*

JAEA-Research 2016-020, 50 Pages, 2017/01

JAEA-Research-2016-020.pdf:6.02MB

In this report, we developed a compartment model of radionuclide migration in environment based on exposure pathways in a river basin scale and performed a preliminary calculation. The results showed good agreement with some measurement, although the comparison of bed sediment, transportation to outer sea and to agricultural products with the measurement was not enough. We continue to validate the model.

Journal Articles

Geological mapping on the shafts and galleries walls on the Mizunami Underground Research Laboratory project

Tsuruta, Tadahiko; Sasao, Eiji

Oyo Chishitsu, 56(6), p.298 - 307, 2016/02

Japan Atomic Agency (JAEA) are performing Mizunami Underground Research Laboratory project (MIU project), which is a broad scientific study of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes. Geological investigations, reflection seismic surveys, borehole drilling, etc., are carried out to understand the distribution and properties of important geological structures (permeable fractures, faults, etc). This report summarizes specifications and data characteristic of geological mapping on the shafts and gallery wall, and describes contributions to developments of geological model based on the results of geological mapping.

Journal Articles

Activities for the environmental recovery from the Fukushima Daiichi Nuclear Power Plant accident by JAEA

Tsuruta, Tadahiko; Harada, Hisaya; Misono, Toshiharu; Iijima, Kazuki

Enganiki Gakkai-Shi, 28(3), p.2 - 6, 2015/12

no abstracts in English

Journal Articles

The Behaviour of radiocaesium deposited in an upland reservoir after the Fukushima Nuclear Power Plant accident

Funaki, Hironori; Hagiwara, Hiroki; Tsuruta, Tadahiko

Materials Research Society Symposium Proceedings, Vol.1665, p.165 - 170, 2014/09

JAEA Reports

Study on geology on the Mizunami Underground Research Laboratory Project; Geology and geological structure from G.L. -300m to G.L. -500m

Tsuruta, Tadahiko; Sasao, Eiji; Kawamoto, Koji; Kuboshima, Koji; Ishibashi, Masayuki

JAEA-Research 2013-014, 35 Pages, 2013/11

JAEA-Research-2013-014.pdf:12.15MB

JAEA is performing the Mizunami Underground Research Laboratory (MIU) Project in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in the fractured crystalline rock. The Project has three overlapping phases with a total duration of about 20 years, and is under the Phase II (Construction phase) and the Phase III (Operation phase). One of the Phase II goals is set up to develop and revise models of the geological environment using the investigation results, and to determine and assess changes in the geological environment in response to excavation. This report aims compiling the study on geology and geological structure from G.L. -300m to G.L. -500m, excavated in the fiscal years from FY2008 to FY2012, and provides the fundamental information on the geology and geological structure for future study and modelling of geological environment. The compiling data are utilized in the updating of the geological models.

JAEA Reports

Mizunami Underground Research Laboratory Project annual report for fiscal year 2011

Kunimaru, Takanori; Mikake, Shinichiro; Nishio, Kazuhisa; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Sasao, Eiji; Hikima, Ryoichi; Tanno, Takeo; Sanada, Hiroyuki; et al.

JAEA-Review 2013-018, 169 Pages, 2013/09

JAEA-Review-2013-018.pdf:15.71MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II and the Phase III in 2011 fiscal year. This report shows the results of the investigation, construction and collaboration studies in fiscal year 2011, as a part of the Phase II and Phase III based on the MIU Master Plan updated in 2010.

JAEA Reports

Study on geology on the Mizunami Underground Research Laboratory Project; Geology and geological structure from the surface to G.L. -300m

Kuboshima, Koji; Ishibashi, Masayuki; Sasao, Eiji; Tsuruta, Tadahiko; Tagami, Masahiko*; Yuguchi, Takashi

JAEA-Research 2012-037, 78 Pages, 2013/03

JAEA-Research-2012-037.pdf:235.85MB

The MIU (Mizunami Underground Research Laboratory) Project has three overlapping phases, Surface-based investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). Currently, the project is under Phase II and Phase III. One of Phase II goals is set up to develop and revise models of the geological environment using the investigation results obtained during excavation, and to determine and assess changes in the geological environment in response to excavation. This report aims compiling results of study on geology and geological structure from the surface to G.L. -300m in the Phase II and provides the fundamental information on the geology and geological structure for future study. The compiling results of this report reflected basic data are utilized in the updating of the geological models in the Phase II.

JAEA Reports

Development of geological structure modeling technology based on regional tectonic process (Joint research)

Tagami, Masahiko*; Yamada, Yasuhiro*; Yamashita, Yoshihiko*; Miyakawa, Ayumu*; Matsuoka, Toshifumi*; Xue, Z.*; Tsuji, Takeshi*; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Amano, Kenji; et al.

JAEA-Research 2012-036, 110 Pages, 2013/02

JAEA-Research-2012-036.pdf:44.93MB

Northeast strike faults developed in and around the Mizunami Underground Research Laboratory (MIU) control groundwater flow. These faults were possibly formed as a part of pull-apart structure by the right lateral movement of the Tsukiyoshi fault distributed in the north of MIU site. But the formational mechanism of these faults is still uncertain. In this joint research, the analog experiment and the numerical simulation were used to restore the geological structures around MIU site. The paleo-stress analysis were exposed an ancient deformation mechanism, and the formation timing was presumed in the regional tectonics. The results are adopted for the design of the analog experiment and the numerical simulation. The results of obtained analog experiment and numerical simulation are verified three-dimensionally, and then compared to the current geological structure model. Then the geological structure in the uninvestigated area is estimated.

Journal Articles

Geological investigations for geological model of deep underground geoenvironment at the Mizunami Underground Research Laboratory (MIU)

Tsuruta, Tadahiko; Tagami, Masahiko; Amano, Kenji; Matsuoka, Toshiyuki; Kurihara, Arata; Yamada, Yasuhiro*; Koike, Katsuaki*

Chishitsugaku Zasshi, 119(2), p.59 - 74, 2013/02

Japan Atomic Energy Agency (JAEA) is developing a geoscientific research project, Mizunami Underground Research Laboratory (MIU) project, in order to establish scientific and technological basis for geological disposal of HLW. A series of geological mapping, reflection seismic survey, borehole investigation and geological investigations around research galleries are carried out to identify the distribution and the heterogeneity of fractures and faults that are potential major flow-pass of groundwater as field investigations. This paper describes geological investigations in the MIU project, focused on the evaluation of their effectiveness in order to understand the deep underground geological environment.

Journal Articles

The Spatial variation of initial $$^{87}$$Sr/$$^{86}$$Sr ratios in the Toki granite, Central Japan; Implications for the intrusion and cooling processes of a granitic pluton

Yuguchi, Takashi; Tsuruta, Tadahiko; Hama, Katsuhiro; Nishiyama, Tadao*

Journal of Mineralogical and Petrological Sciences, 108(1), p.1 - 12, 2013/02

 Times Cited Count:11 Percentile:54.04(Mineralogy)

The spatial variation in initial $$^{87}$$Sr/$$^{86}$$Sr ratios (SrI) in the Toki granite, Central Japan, shows heterogeneity ranging from 0.708942 to 0.710069, which provides information on formation processes of plutons. The Toki granite has three mineralogy-based rock facies: muscovite-biotite granite (MBG), hornblende-biotite granite (HBG) and biotite granite (BG). Large SrI values were found to be distributed at the western margin (west MBG) and the lithologically central region (central BG), while small SrI values were found at the northeast margin (northeast MBG). Regions with high and low Sr concentrations were also found in the Toki granite. In the Sr-rich samples, SrI (0.708942-0.709789) increases with 100/Sr (0.7-1.5). This geochemical trend extends towards the country sedimentary rocks of the Mino Terrane, which can be interpreted to result from assimilation and fractional crystallization (AFC) between the original granitic magma and the Mino sedimentary rocks. The SrI values in the Sr-rich regions show a correlation with the Alumina Saturation Index (ASI). In particular, the west MBG, with large SrI values, is classified as a peraluminous granitoid, suggesting that the western margin of the pluton was strongly affected by assimilation during the intrusion process. The Sr-poor samples are present both in the central BG, with large SrI values, and in the northeast MBG, with small SrI values. The Sr-poor samples have small ASI and large differentiation indices, indicating that the central BG and the northeast MBG were generated either by different AFC process with different amounts of contaminants or by the intrusion and fractionation of different source magma with different SrI values. Overall, the geochemical spatial variations found in the Toki granite can be explained by various degrees of assimilation and fractional crystallization in the magma chamber and/or multi-stage intrusions with different degrees of crystallization of plural source magmas.

JAEA Reports

Mizunami Underground Research Laboratory Project; Compilation of results of geological investigation at the shafts and research galleries from the depth of 300m to 500m

Kawamoto, Koji; Kuboshima, Koji; Ishibashi, Masayuki; Tsuruta, Tadahiko; Sasao, Eiji; Ikeda, Koki; Mikake, Shinichiro; Hara, Ikuo; Yamamoto, Masaru

JAEA-Data/Code 2012-025, 32 Pages, 2013/01

JAEA-Data-Code-2012-025.pdf:3.03MB
JAEA-Data-Code-2012-025-appendix.zip:126.32MB

This document presents the data of geological investigations in the shafts and research galleries from the depth of 300m to 500m of the MIU from the 2008 fiscal year to the 2011 fiscal year. In the shafts and research galleries of the MIU, although the Cretaceous Toki granite is distributed, pegmatite, aplite and lampropyre dike are distributed partially.

Journal Articles

Three-dimensional fracture distribution in relation to local cooling in a granitic body; An Example from the Toki granitic pluton, Central Japan

Yuguchi, Takashi; Tagami, Masahiko*; Tsuruta, Tadahiko; Nishiyama, Tadao*

Engineering Geology, 149-150, p.35 - 46, 2012/11

 Times Cited Count:7 Percentile:56.62(Engineering, Geological)

This paper describes the spatial distribution of fractures in the Toki granitic pluton, Central Japan and their evaluation with respect to the pluton's cooling behavior. Three-dimensional frequency distributions of entire fractures, based on borehole television data collected from 19 boreholes, shows that (1) the central region of the granite has a high fracture frequency and (2) fracture frequency decreases with decreasing elevation (datum is mean sea level), with the exception of the west side of the body. The development of sub-solidus reaction features was measured at two neighboring positions, and the difference was divided by the distance between the two positions. The resulting quantity is here defined as "local cooling rate". We observed a significant correlation between the distribution patterns of entire fracture frequency and local cooling rate; the region with a high local cooling rate corresponds to the region with a high frequency of entire fractures, and vice versa. This correlation indicates that fracture genesis can be explained by "local cooling rate", combined with the concept of thermal stress. Thus, the three dimensional pattern of local cooling rate is a potential diagnostic tool for quantifying the distribution of fracture frequency.

JAEA Reports

Mizunami Underground Research Laboratory Project, Plan for fiscal year 2012

Kunimaru, Takanori; Mikake, Shinichiro; Nishio, Kazuhisa; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Kuboshima, Koji; Takeuchi, Ryuji; Mizuno, Takashi; Sato, Toshinori; et al.

JAEA-Review 2012-028, 31 Pages, 2012/08

JAEA-Review-2012-028.pdf:3.86MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU project is planned in three overlapping phases; Surface-based Investigation Phase (Phase I), Construction Phase (Phase II) and Operation Phase (Phase III). Currently, the project is under the Construction Phase and the Operation Phase. This document introduces the research and development activities planned for 2012 fiscal year based on the MIU Master Plan updated in 2010, construction plan and research collaboration plan, etc.

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