Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

https://shop.elsevier.com/books/sodium-cooled-fast-reactors/morishita/978-0-12-824076-2

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

Factors controlling dissolved Cs concentrations in east Japanese rivers

Tsuji, Hideki*; Ishii, Yumiko*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; et al.

Science of the Total Environment, 697, p.134093_1 - 134093_11, 2019/12

https://doi.org/10.1016/j.scitotenv.2019.134093

To investigate the main factors that control the dissolved radiocesium concentration in river water in the area affected by the Fukushima Daiichi Nuclear Power Plant accident, the correlations between the dissolved Cs concentrations at 66 sites normalized to the average Cs inventories for the watersheds with the land use, soil components, topography, and water quality factors were assessed. We found that the topographic wetness index is significantly and positively correlated with the normalized dissolved Cs concentration. Similar positive correlations have been found for European rivers because wetland areas with boggy organic soils that weakly retain Cs are mainly found on plains. However, for small Japanese river watersheds, the building area ratio in the watershed strongly affected the dissolved Cs concentration.

3D geostatistical modeling of fracture system in a granitic massif to characterize hydraulic properties and fracture distribution

Koike, Katsuaki*; Kubo, Taiki*; Liu, C.*; Masoud, A.*; Amano, Kenji; Kurihara, Arata*; Matsuoka, Toshiyuki; Lanyon, B.*

Tectonophysics, 660, p.1 - 16, 2015/10

https://doi.org/10.1016/j.tecto.2015.06.008

This study integrates 3D models of rock fractures from different sources and hydraulic properties aimed at identifying relationships between fractures and permeability. A geostatistical method (GEOFRAC) that can incorporate orientations of sampled data was applied to 50,900 borehole fractures for spatial modeling of fractures over a 12 km by 8 km area, to a depth of 1.5 km. GEOFRAC produced a plausible 3D fracture model, in that the orientations of simulated fractures correspond to those of the sample data and the continuous fractures appeared near a known fault. Small-scale fracture distributions with dominant orientations were also characterized around the two shafts using fracture data from the shaft walls. By integrating the 3D model of hydraulic conductivity using sequential Gaussian simulation with the GEOFRAC fractures from the borehole data, the fracture sizes and directions that strongly affect permeable features were identified.

Hydrogen-bond network and pH sensitivity in human transthyretin

Yokoyama, Takeshi*; Mizuguchi, Mineyuki*; Nabeshima, Yuko*; Kusaka, Katsuhiro*; Yamada, Taro*; Hosoya, Takaaki*; Ohara, Takashi; Kurihara, Kazuo; Tanaka, Ichiro*; Niimura, Nobuo*

Journal of Synchrotron Radiation, 20(6), p.834 - 837, 2013/11

https://doi.org/10.1107/S090904951302075X

Transthyretin (TTR) is a tetrameric protein. TTR misfolding and aggregation are associated with human amyloid diseases. Dissociation of the TTR tetramer is believed to be the rate-limiting step in the amyloid fibril formation cascade. Low pH is known to promote dissociation into monomer and the formation of amyloid fibrils. In order to reveal the molecular mechanisms underlying pH sensitivity and structural stabilities of TTR, neutron diffraction studies were conducted using the IBARAKI Biological Crystal Diffractometer with the time-of-flight method. Crystals for the neutron diffraction experiments were grown up to 2.5 mm for four months. The neutron crystal structure solved at 2.0 revealed the protonation states of His88 and the detailed hydrogen-bond network depending on the protonation states of His88. This hydrogen-bond network is involved in monomer-monomer and dimer-dimer interactions, suggesting that the double protonation of His88 by acidification breaks the hydrogen-bond network and causes the destabilization of the TTR tetramer. Structural comparison with the X-ray crystal structure at acidic pH identified the three amino acid residues responsible for the pH sensitivity of TTR. Our neutron model provides insights into the molecular stability related to amyloidosis.

Neutron and X-ray crystallographic analysis of protease I at pD 8.0; Protonation states and hydration structure in the free-form

Onishi, Yuki*; Yamada, Taro*; Kurihara, Kazuo; Tanaka, Ichiro*; Sakiyama, Fumio*; Masaki, Takeharu*; Niimura, Nobuo*

Biochimica et Biophysica Acta; Proteins and Proteomics, 1834(8), p.1642 - 1647, 2013/08

https://doi.org/10.1016/j.bbapap.2013.05.012

The structure of the free-form of protease I (API) at pD 8.0 was refined by simultaneous use of single crystal X-ray and neutron diffraction data sets to investigate the protonation states of key catalytic residues of the serine protease. Occupancy refinement of the catalytic triad in the active site of API free-form showed that ca. 30% of the imidazole ring of H57 and ca. 70% of the hydroxyl group of S194 were deuterated. This observation indicates that a major fraction of S194 is protonated in the absence of a substrate. The protonation state of the catalytic triad in API was compared with the bovine -trypsin-BPTI complex. The comparison led to the hypothesis that close contact of a substrate with S194 could lower the acidity of its hydroxyl group, thereby allowing H57 to extract the hydrogen from the hydroxyl group of S194. H210, which is a residue specific to API, does not form a hydrogen bond with the catalytic triad residue D113. Instead, H210 forms a hydrogen bond network with S176, H177 and a water molecule. The close proximity of the bulky, hydrophobic residue W169 may protect this hydrogen bond network, and this protection may stabilize the function of API over a wide pH range.

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.

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

https://doi.org/10.5575/geosoc.2011.0010

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.

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.

Hydrogen-bond network and pH sensitivity in transthyretin; Neutron crystal structure of human transthyretin

Yokoyama, Takeshi*; Mizuguchi, Mineyuki*; Nabeshima, Yuko*; Kusaka, Katsuhiro*; Yamada, Taro*; Hosoya, Takaaki*; Ohara, Takashi*; Kurihara, Kazuo; Tomoyori, Katsuaki*; Tanaka, Ichiro*; et al.

Journal of Structural Biology, 177(2), p.283 - 290, 2012/02

https://doi.org/10.1016/j.jsb.2011.12.022

Geostatistic analysis for groundwater flow and hydraulic parameters in deep granitic body

Kubo, Taiki*; Koike, Katsuaki*; Kurihara, Arata*; Matsuoka, Toshiyuki

Heisei-23 Nendo (2011 Nen) Shigen, Sozai Gakkai Shuki Taikai Koenshu, p.369 - 370, 2011/09

no abstracts in English