Assessment of caesium-137 detections at CTBTO radionuclide monitoring stations in East Asia and their relationship to Asian dust dispersion

Furuno, Akiko; Omori, Ryuta*; Tateoka, Hisanori*; Minakawa, Yuya*; Kurihara, Toshiyuki; Yamamoto, Yoichi; Tomita, Yutaka

Pure and Applied Geophysics, 182(12), p.5175 - 5188, 2025/12

https://doi.org/10.1007/s00024-024-03620-y

The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) Okinawa radionuclide monitoring station (JPP37) is located on a hill facing the East China Sea at the center of the main island of Okinawa. It occasionally detects Cs-137, although no nuclear facilities are located on the island. This study focused on the detection of Cs-137 at JPP37 and examined the ratio of simultaneous detections at nearby stations of the International Monitoring System (IMS) of the CTBTO and the relationship with Asian dust from inland East Asia. The detection of Cs-137 in JPP37 from 2020 to 2023, which motivated this study, was high in spring. Among the nine IMS radionuclide stations in East Asia, the detections in Beijing, Lanzhou, and Ulaanbaatar, Mongolia, were also high in spring. This suggested a high association with the detection of Asian dust in East Asia. Thus, we confirmed the detection of Cs-137 at nine nearby IMS stations when Asian dust was observed at any of the sites in Japan. In addition, we observed that the detection rates were high in Takasaki, Beijing, Lanzhou, and Ulaanbaatar. It can be inferred that the Cs-137 observed mainly in spring at the IMS particulate radionuclide stations in the East Asian region around Japan were likely to pick up the effects of global fallout conveyed by Asian dust. Thereafter, we conducted a preliminary source estimation analysis for Asian dust arrival near Japan. Atmospheric dispersion simulations explained the detection of Cs-137 at nearby IMS particulate radionuclide stations, assuming that Cs-137 was emitted from the desert, the source of the Asian dust.

Beam commissioning of the linac for iBNCT

Naito, Fujio*; Anami, Shozo*; Ikegami, Kiyoshi*; Uota, Masahiko*; Ouchi, Toshikatsu*; Onishi, Takahiro*; Oba, Toshiyuki*; Obina, Takashi*; Kawamura, Masato*; Kumada, Hiroaki*; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1244 - 1246, 2016/11

http://www.pasj.jp/web_publish/pasj2016/proceedings/PDF/TUP1/TUP118.pdf

The proton linac installed in the Ibaraki Neutron Medical Research Center is used for production of the intense neutron flux for the Boron Neutron Capture Therapy (BNCT). The linac consists of the 3-MeV RFQ and the 8-MeV DTL. Design average beam current is 10mA. Target is made of Beryllium. First neutron production from the Beryllium target was observed at the end of 2015 with the low intensity beam as a demonstration. After the observation of neutron production, a lot of improvement s was carried out in order to increase the proton beam intensity for the real beam commissioning. The beam commissioning has been started on May 2016. The status of the commissioning is summarized in this report.

3D hydraulic conductivity modeling of fractured granitic body using geostatistical techniques and its application to regional groundwater flow analysis

Kubo, Taiki*; Koike, Katsuaki*; Liu, C.*; Kurihara, Arata*; Matsuoka, Toshiyuki

Chigaku Zasshi, 122(1), p.139 - 158, 2013/03

https://doi.org/10.5026/jgeography.2012ap02

Numerical simulations have been the most effective method for estimating flow pattern, flux, and flow velocity of the groundwater to precisely characterize large-scale groundwater systems. Spatial modeling of the 3D distribution of hydraulic conductivity over a study area is indispensable to obtain accurate simulation results. However, such spatial modeling is difficult in most cases due to the limitations of hydraulic conductivity data in terms of their volume and location. To overcome these problems and establish an advanced technique, we adopt geostatistics and combine a fracture distribution model with measured conductivity data, selecting the Tono area situated in Gifu Prefecture, central Japan for the field study. The size of the main target area covers 12 km (E-W) by 8 km (N-S), with a depth range of 1.5 km, and it is chiefly underlain by Cretaceous granite. Because the distribution of 395 hydraulic test data acquired along the 25 deep boreholes was biased, the data values were compared to the dimensions of simulated fractures using GEOFRAC. As a result, a positive correlation was identified. Using a regression equation for the correlation, hydraulic conductivity values were assigned to every simulated fracture. Then, a sequential Gaussian simulation (SGS) was applied to construct a 3D spatial model of hydraulic conductivity using those assumed values and actual test data. The plausibility of the resulting model was confirmed through the continuity of high and low permeable zones. The next step is a groundwater flow simulation using MODFLOW and the model. The simulation results were regarded to be appropriate because distribution of hydraulic head, locations of major discharge points, and anisotropy of hydraulic behavior of the Tsukiyoshi fault correspond to the results of observations.

Development of geological models in the Mizunami Underground Research Laboratory Project; Updating from "Shaft180 geological model" to "Stage300 geological model" in Phase 2

Ishibashi, Masayuki; Kurihara, Arata*; Matsuoka, Toshiyuki; Sasao, Eiji

JAEA-Research 2012-018, 48 Pages, 2012/07

JAEA-Research-2012-018.pdf:8.48MB
JAEA-Research-2012-018(errata).pdf:1.13MB
JAEA-Research-2012-018-appendix(CD-ROM).zip:13.81MB

This document presents about updating of geological models at the Phase 2 in the Mizunami underground research laboratory project. In the phase 2, the geological models has been updated four times (Shaft180 geological model, Pilot500 geological model, Sustage200 geological model, Stage300 geological model) based on geological mapping date and/or some borehole investigation data at the shafts and research galleries. These geological models represent distributions of lithofacies and/or geological structures based on each geological investigation. In order to evaluate relationship between understanding of geological environments and progress of investigations, to organize the history of geological models updating is important.

Study on Geology on Mizunami Underground Research Laboratory Project; Annual report for fiscal year 2008

Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Hodotsuka, Yasuyuki; Tagami, Masahiko; Ishida, Hideaki; Hayano, Akira; Kurihara, Arata; Yuguchi, Takashi

JAEA-Research 2010-039, 131 Pages, 2011/01

JAEA-Research-2010-039.pdf:25.36MB

Tono Geoscientific Unit of Geological Isolation and Development Directoratte is performing Mizunami Underground Research Laboratory (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, in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. The MIU Project has three overlapping 3 phases, with a total duration of 20 years. The project goals of the MIU Project from Phase I through to Phase III are: to establish techniques for investigation, analysis and assessment of the deep geological environment, and to develop a range of engineering for deep underground application. Currently, the project is under the Phase II. This document presents the overview of results of the research and development on "geology" performed in fiscal year 2008, with regard to the Phase II goal.

A Neutron crystallographic analysis of a cubic porcine insulin at pD 6.6

Ishikawa, Takuya*; Chatake, Toshiyuki*; Onishi, Yuki*; Tanaka, Ichiro*; Kurihara, Kazuo; Kuroki, Ryota; Niimura, Nobuo*

Chemical Physics, 345(2-3), p.152 - 158, 2008/04

https://doi.org/10.1016/j.chemphys.2007.06.053

Development of the supervisory discharge operation monitoring system for JT-60

Sueoka, Michiharu; Totsuka, Toshiyuki; Kawamata, Yoichi; Kurihara, Kenichi; Seki, Akiyuki

Fusion Engineering and Design, 83(2-3), p.283 - 286, 2008/04

https://doi.org/10.1016/j.fusengdes.2008.01.006

For safety and efficient operation of a fusion device, appropriate information should be provided to the personnel related to experiment. In order to realize this, we have newly developed highlight screens displaying the plasma movie, the status of discharge sequence, the discharge schedule, the present status of trouble, etc., with the large (65 inch) monitor TV in front of the central consoles. These highlight screens are automatically switched according to the timing signal of JT-60 discharge sequence and/or the operator's request. We call this system the supervisory discharge operation monitoring system. This report deals with the technical details of this system including the plasma movie database system and the discharge information management system.

Recent results on hydrogen and hydration in biology studied by neutron macromolecular crystallography

Niimura, Nobuo; Arai, Shigeki; Kurihara, Kazuo; Chatake, Toshiyuki*; Tanaka, Ichiro*; Bau, R.*

Cellular and Molecular Life Sciences, 63(3), p.285 - 300, 2006/02

https://doi.org/10.1007/s00018-005-5418-3

Neutron diffraction provides an experimental method of directly locating hydrogen atoms in proteins and DNA oligomers. Three different types of high resolution neutron diffractometers for biological macromolecules have been constructed in Japan, France and the U.S.A., and they have all been actively used in recent years to determine the crystal structures of numerous proteins. Examples include the detailed geometries of hydrogen bonds, information on H/D exchange in proteins, the unambiguous location of protons, the role of key hydrogen atoms in enzymatic activity and thermostability, and the dynamical behavior of hydration structures, all of which have been extracted from these structural results and reviewed in this article. Other important techniques, such as the optimization of growth of large single crystals using phase diagrams, the preparation of fully deuterated proteins, the introduction of cryogenic techniques to neutron protein crystallography, and the establishment of a "hydrogen and hydration in proteins" database, will also be described in this paper.

Hydrogen and hydration in proteins and nucleic acids; Neutron diffraction from bio-macromolecules at JAERI

Niimura, Nobuo; Arai, Shigeki; Kurihara, Kazuo; Chatake, Toshiyuki*; Tanaka, Ichiro*; Bau, R.*

Hydrogen- and Hydration-Sensitive Structural Biology, p.17 - 35, 2005/00

At the JAERI, we have constructed several high-resolution neutron diffractometers dedicated to biological macromolecules (called BIX-type diffractometers), which use a monochromatized neutron beam and a neutron imaging plate detector. In this paper, we review several interesting results regarding hydrogen positions and hydration in proteins, obtained using the two BIX-type diffractometers in JAERI. The general subject of neutron protein crystallography has been reviewed by several authors, and several selected topics have been discussed.

Neutron crystallographic study on rubredoxin from by BIX-3, a single-crystal diffractometer for biomacromolecules

Kurihara, Kazuo; Tanaka, Ichiro*; Chatake, Toshiyuki*; Adams, M. W. W.*; Jenney, F. E. Jr.*; Moiseeva, N.*; Bau, R.*; Niimura, Nobuo

Proceedings of the National Academy of Sciences of the United States of America, 101(31), p.11215 - 11220, 2004/08

https://doi.org/10.1073/pnas.0403807101

The structure of a rubredoxin (Rd) from , an organism that grows optimally at 100 C, was determined using the neutron single-crystal diffractometer for biological macromolecules (BIX-3) at the JRR-3 reactor of JAERI. Data were collected at room temperature up to a resolution of 1.5 , and the completeness of the data set was 81.9 %. The model contains 306 H atoms and 50 D atoms. A total of 37 hydration water molecules were identified. The model has been refined to final agreement factors of = 18.6 % and = 21.7 %. Several orientations of the O-D bonds of side chains, whose assignments from X-ray data were previously ambiguous, were clearly visible in the neutron structure. While most backbone N-H bonds had undergone some degree of H/D exchange throughout the molecule, five H atom positions still had distinctly negative (H) peaks. The neutron Fourier maps clearly showed the details of an extensive set of H bonds involving the ND terminus that may contribute to the unusual thermostability of this molecule.