Temporal changes in radiocesium deposition on the Fukushima floodplain

Nakanishi, Takahiro; Sato, Seiji; Matsumoto, Takumi*

Radiation Protection Dosimetry, 184(3-4), p.311 - 314, 2019/10

https://doi.org/10.1093/rpd/ncz086

There has been significant concern about an increase of exposure dose in living sphere due to the accumulation of radiocesium discharged from contaminated mountainous forest in Fukushima. In this study, we investigated the history of radiocesium deposition on some floodplains in Fukushima. Radiocesium concentrations of river suspended particles and air dose rates at floodplains were also observed continuously. In many situations, annual sediment accumulation at floodplains was only several kg m and its radiocesium concentration was gradually decreasing in line with that of suspended particle. Simultaneously, air dose rates on floodplains were decreasing with time. In 2015 with heavy flood discharge, several hundred kg m of sediment accumulation and sharply decrease of air dose rate was observed at rivers without reservoir. Conversely, radiocesium accumulation at floodplain was significant reduced due to deposition on upstream reservoir.

Monitoring of groundwater inflow into research galleries in the Mizunami Underground Research Laboratory Project (MIU Project); From fiscal year 2012 to 2013

Ueno, Tetsuro; Sato, Seiji; Takeuchi, Ryuji

JAEA-Data/Code 2014-018, 37 Pages, 2014/11

JAEA-Data-Code-2014-018.pdf:3.64MB
JAEA-Data-Code-2014-018-appendix(CD-ROM).zip:0.57MB

Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) 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 started the Phase III in 2010 fiscal year. The groundwater inflow monitoring into shafts and research galleries has been continued to achieve the Phase II goals. This document presents the results of the groundwater inflow monitoring from fiscal year 2012 to 2013.

Annual data compilation of water balance observation in the Regional Hydrogeological Study Project (RHS Project); For the fiscal year 2012

Sato, Seiji; Ogata, Nobuhisa

JAEA-Data/Code 2014-003, 22 Pages, 2014/05

JAEA-Data-Code-2014-003.pdf:10.84MB
JAEA-Data-Code-2014-003-appendix(CD-ROM).zip:25.03MB

The Tono Geoscientific Research Unit of Japan Atomic Energy Agency (JAEA) has carried out the subsurface water balance observation in order to estimate groundwater recharge rate for setting the upper boundary conditions on groundwater flow simulation and for obtaining data for calibration of hydrogeological model. In the subsurface water balance observations, precipitation data and river flow rate have been observed in the Garaishi River and the Hiyoshi River watersheds. The missing or abnormal data in the monitoring data during the fiscal year 2012 were complemented or corrected, and these data were compiled in data set.

Monitoring of groundwater inflow into research galleries in the Mizunami Underground Research Laboratory Project (MIU Project); From fiscal year 2004 to 2011

Sato, Seiji; Ogata, Nobuhisa; Takeuchi, Ryuji; Takeda, Masaki

JAEA-Data/Code 2013-020, 38 Pages, 2014/01

JAEA-Data-Code-2013-020.pdf:12.13MB
JAEA-Data-Code-2013-020-appendix(CD-ROM).zip:1.41MB

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 started the Phase III in 2010 fiscal year. One of the Phase II goals, which is for the project goal, was set to develop and revise models of the geological environment using the investigation results obtained during underground facilities excavation, and to determine and assess changes in the geological environment in response to excavation. The groundwater inflow monitoring into shafts and research galleries has been continued to achieve the Phase II goals. This document presents the results of the groundwater inflow monitoring from fiscal year 2004 to 2011.

Annual data compilation of water balance observation in the Mizunami Underground Research Laboratory Project (MIU Project); For the fiscal year 2010 to 2011

Sato, Seiji; Ogata, Nobuhisa; Takeuchi, Ryuji; Takeda, Masaki

JAEA-Data/Code 2013-016, 50 Pages, 2013/12

JAEA-Data-Code-2013-016.pdf:7.85MB
JAEA-Data-Code-2013-016-appendix(DVD-ROM).zip:514.1MB

The Tono Geoscientific Research Unit of Japan Atomic Energy Agency (JAEA) has carried out the subsurface water balance observation in order to estimate groundwater recharge rate for setting the upper boundary conditions on groundwater flow simulation and to obtain data for calibration of hydrogeological model. In the subsurface water balance observations, meteorological data, river flow rate, groundwater level and soil moisture to estimate precipitation and evapotranspiration have been observed in the Shoba River watershed, the Shoba River model watershed and MIU Construction Site. After missed data and data error in the monitoring data from the fiscal year 2010 to 2011 were complemented or corrected, the data was compiled in data set. Furthermore the groundwater recharge rates in the Hazama River watershed were calculated using the river flow rate data obtained from the environment survey in the MIU construction work from Fiscal year 2003 to 2011.

Annual data compilation of water balance observation in the Regional Hydrogeological Study Project (RHS Project); For the fiscal year 2010

Sato, Seiji; Takeda, Masaki; Takeuchi, Ryuji

JAEA-Data/Code 2013-003, 19 Pages, 2013/06

JAEA-Data-Code-2013-003.pdf:2.36MB
JAEA-Data-Code-2013-003-appendix(CD-ROM).zip:15.46MB

The Tono Geoscientific Research Unit of Japan Atomic Energy Agency (JAEA) has carried out the subsurface water balance observation in order to estimate groundwater recharge rate for setting the upper boundary conditions on groundwater flow simulation and to obtain data for the calibration of the hydrogeological model. In the subsurface water balance observations, rainfall data and river flow rate have been observed in the Garaishi river and the Hiyoshi river watersheds. The missed data and data error in the monitoring data during the fiscal year 2010 were complemented or corrected, and these data were compiled in data set. Both of the observation data and compiled data are included into the data set, and the data set is recorded on CD-ROM.

Computer Simulation of Fluid Flow in a Single Fracture with "In-Plane Heterogeneity" Considered

Muraoka, Tamotsu*; Sato, Seiji*; Yamamoto, Asao*; Yatake, Yoichi*; Asano, Rinichi*; Yamamoto, Ryuichi*

JNC TJ8400 2003-074, 160 Pages, 2004/01

JNC-TJ8400-2003-074.pdf:909.35MB

The heterogeneity of the transmissivity and aperture in a single fracture, so called "in-plane heterogeneity", is considered to have an effect on the migration of radionuclides in a host rock of geological disposal of nuclear wastes. Aiming at better understanding of this effect for the safety assessment of geological disposal, we have improved the computer simulation code for the 3D flow and transport analysis in a single fracture developed in 2002 using the lattice Gas Automaton (LGA) method, and we have conducted the various flow and transport simulations using the 3D fracture models. Upon the improvement of the LGA code, we have investigated the macroscopic averaging method for the pseudo-4D face-centered-hypercubic (FCHC) model of 3D LGA simulation to come up with relation to map the numerical results of the LGA code onto real physical quantities such as pressure and velocity. Furthermore, we have improved the usability of the LGA code and its computational efficiency by algorithm tuning and parallel processing. We have also surveyed the results of the previous research on the in-plane heterogeneity of single fractures, examined the parameters to describe the heterogeneity, and obtained the 3D mathmatical model by S.R. Brown and P.W.J. Glover to create fractally rough synthetic fractures with these parameters reproduced well. Based on the above results, we have conducted the 3D simulations of fluid flow and mass transport in various numerically synthesized fractures. Finally, we have evaluated the effects of the parameters describing the in-plane heterogeneity on the property of fluid flow and mass transport through single fractures.

None

*; Sato, Seiji*; *; Naruki, Kaoru

JNC TJ1400 2000-010, 71 Pages, 2000/03

JNC-TJ1400-2000-010.pdf:2.11MB

None

Kinetics and mechanisms of the reactions of CH and CD with HS and DS

Sato, K.*; *; *; *; *; Kurosaki, Yuzuru*; Takayanagi, Toshiyuki

Chemical Physics, 242(1), p.1 - 10, 1999/00

https://doi.org/10.1016/S0301-0104(98)00420-0

no abstracts in English

Study on hydrogeology in crystalline fractured rock; Current status of long-term hydraulic pressure monitoring during construction phase (phase 2)

Beppu, Shinji; Onoe, Hironori; Sato, Seiji; Onuki, Kenji; Takeuchi, Ryuji; Ogata, Nobuhisa

no journal, , 

no abstracts in English