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Journal Articles

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

 Times Cited Count:2 Percentile:34.3(Environmental Sciences)

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$$^{-2}$$ 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$$^{-2}$$ 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.

Journal Articles

Conceptual plant system design study of an experimental HTGR upgraded from HTTR

Ohashi, Hirofumi; Goto, Minoru; Ueta, Shohei; Sato, Hiroyuki; Fukaya, Yuji; Kasahara, Seiji; Sasaki, Koei; Mizuta, Naoki; Yan, X.; Aoki, Takeshi*

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 6 Pages, 2018/10

Conceptual design study of an experimental HTGR is performed to upgrade the plant system from Japanese High Temperature engineering Test Reactor (HTTR) to a commercial HTGR. Safety systems of HTTR are upgraded to demonstrate the commercial HTGR concept, such as a passive reactor cavity cooling system, a confinement, etc. An intermediate heat exchanger (IHX) is replaced by a steam generator (SG) for a process heat supply to demonstrate the technology for a commercial use. This paper describes the conceptual design study results of the plant system of the experimental HTGR.

Journal Articles

Electronic structure of Li$$^{+}$$@C$$_{60}$$; Photoelectron spectroscopy of the Li$$^{+}$$@C$$_{60}$$[PF$$_{6}$$$$^{-}$$] salt and STM of the single Li$$^{+}$$@C$$_{60}$$ molecules on Cu(111)

Yamada, Yoichi*; Kuklin, A. V.*; Sato, Sho*; Esaka, Fumitaka; Sumi, Naoya*; Zhang, C.*; Sasaki, Masahiro*; Kwon, E.*; Kasama, Yasuhiko*; Avramov, P. V.*; et al.

Carbon, 133, p.23 - 30, 2018/07

 Times Cited Count:4 Percentile:70.78(Chemistry, Physical)

We report first STM observation of the Li$$^{+}$$ ion endohedral C$$_{60}$$, which is of a new class of endohedral fullerenes, prepared by means of evaporation of high-purity Li$$^{+}$$@C$$_{60}$$[PF$$_{6}$$$$^{-}$$] salt in ultra-high vacuum. Prior to the STM measurements, the electronic structure of Li$$^{+}$$@C$$_{60}$$ in the Li$$^{+}$$@C$$_{60}$$[PF$$_{6}$$$$^{-}$$] salt was also precisely determined. In the salt, it is shown that Li and PF$$_{6}$$ have nearly single positive and negative charge, respectively, and the C$$_{60}$$ cage is nearly neutral, suggesting that Li$$^{+}$$@C$$_{60}$$ in the salt retains its original electronic state.

Journal Articles

Design of HTTR-GT/H$$_{2}$$ test plant

Yan, X. L.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu*; Horii, Shoichi*; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.

Nuclear Engineering and Design, 329, p.223 - 233, 2018/04

 Times Cited Count:6 Percentile:15.83(Nuclear Science & Technology)

The pre-licensing design of an HTGR cogeneration test plant to be coupled to JAEA's existing test reactor HTTR is presented. The plant is designed to demonstrate the system of JAEA commercial plant design GTHTR300C. With construction planned to be completed around 2025, the test plant is expected to be the first-of-a-kind nuclear system operating on two of the advanced energy conversion systems attractive for the HTGR closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.

Journal Articles

HTTR-GT/H$$_{2}$$ test plant; System design

Yan, X.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu; Horii, Shoichi; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.827 - 836, 2016/11

Pre-licensing basic design for a cogenerating HTGR test plant system is presented. The plant to be coupled to existing 30 MWt 950$$^{circ}$$C test reactor HTTR is intended as a system technology demonstrator for GTHTR300C plant design. More specifically the test plant of HTTR-GT/H$$_{2}$$ aims to (1)demonstrate the licensability of the GTHTR300C for electricity production by gas turbine and hydrogen cogeneration by thermochemical process and (2) confirm the operation control and safety of such cogeneration system. With construction and operation completion by 2025, the test plant is expected to be the first of a kind HTGR-powered cogeneration plant operating on the two advanced energy conversion systems of closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2013

Hama, Katsuhiro; Mikake, Shinichiro; Nishio, Kazuhisa; Kawamoto, Koji; Yamada, Nobuto; Ishibashi, Masayuki; Murakami, Hiroaki; Matsuoka, Toshiyuki; Sasao, Eiji; Sanada, Hiroyuki; et al.

JAEA-Review 2014-038, 137 Pages, 2014/12

JAEA-Review-2014-038.pdf:162.61MB

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 fiscal year 2013. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2013, as a part of the Phase II and Phase III based on the MIU Master Plan updated in 2010.

JAEA Reports

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.

Journal Articles

Air shower simulation for WASAVIES; Warning system for aviation exposure to solar energetic particles

Sato, Tatsuhiko; Kataoka, Ryuho*; Yasuda, Hiroshi*; Yashiro, Seiji*; Kuwabara, Takao*; Shiota, Daiko*; Kubo, Yuki*

Radiation Protection Dosimetry, 161(1-4), p.274 - 278, 2014/10

 Times Cited Count:17 Percentile:12.12(Environmental Sciences)

We applied our simulation technique to the analysis of air shower induced by mono-energetic protons and alpha particles, which are the dominant component of SEP. The results of the simulations were summarized in a database containing particle fluxes for each condition as a function of the atmospheric depth. This database was then incorporated into our developing Warning System of AVIation Exposure to SEP called WASAVIES. In this system, the aircrew doses due to SEP exposure are estimated within 6 hours after the flare onset, using the established database multiplied with the SEP fluxes incident to the earth. The MHD Cube model is employed in the determination of the incident SEP fluxes. The procedures for the air shower simulation together with some initial results of the aircrew dose calculations for past ground-level enhancement (GLE) events will be presented at the meeting.

Journal Articles

Radiation dose forecast of WASAVIES during ground-level enhancement

Kataoka, Ryuho*; Sato, Tatsuhiko; Kubo, Yuki*; Shiota, Daiko*; Kuwabara, Takao*; Yashiro, Seiji*; Yasuda, Hiroshi*

Space Weather, 12(6), p.380 - 386, 2014/06

 Times Cited Count:13 Percentile:47.1(Astronomy & Astrophysics)

Solar energetic particles (SEP) sometimes induce air shower that significantly increase the radiation dose at flight altitudes. In order to inform the situation of such a space radiation hazard to aircrews, a physics-based forward model is developed as WASAVIES (Warning System for Aviation Exposure to SEP) based on the focused transport equation and Monte Carlo particle transport simulation of the air shower. WASAVIES gives the fastest and simplest way to predict the time profile of dose rate during ground-level enhancements (GLEs).

JAEA Reports

Annual data compilation of water balance observation in the Mizunami Underground Research Laboratory Project (MIU Project); For the fiscal year 2012

Sato, Seiji; Ogata, Nobuhisa

JAEA-Data/Code 2014-004, 44 Pages, 2014/05

JAEA-Data-Code-2014-004.pdf:17.15MB
JAEA-Data-Code-2014-004-appendix(CD-ROM).zip:278.83MB

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, meteorological data, river flow rate, groundwater level and soil moisture have been observed in the Shoba River watershed, the Shoba River model watershed and the MIU Construction Site. After missing or abnormal data in the monitoring data from the fiscal year 2012 were complemented or corrected, the data were 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 in the Fiscal year 2012.

JAEA Reports

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.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2012

Hama, Katsuhiro; Mikake, Shinichiro; Nishio, Kazuhisa; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Sasao, Eiji; Hikima, Ryoichi*; Tanno, Takeo*; Sanada, Hiroyuki; Onoe, Hironori; et al.

JAEA-Review 2013-050, 114 Pages, 2014/02

JAEA-Review-2013-050.pdf:19.95MB

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 fiscal year 2012. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2012, as a part of the Phase II and Phase III based on the MIU Master Plan updated in 2010.

JAEA Reports

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.

JAEA Reports

Annual data compilation of water balance observation in the Regional Hydrogeological Study Project (RHS Project); For the fiscal year 2011

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

JAEA-Data/Code 2013-017, 24 Pages, 2013/12

JAEA-Data-Code-2013-017.pdf:2.73MB
JAEA-Data-Code-2013-017-appendix(CD-ROM).zip:28.79MB

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, precipitation 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 2011 were complemented or corrected, and these data were compiled in data set.

JAEA Reports

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.

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

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.

Journal Articles

Technical examination on high temperature gas-cooled reactor as energy source of active carbon recycling energy system for steelmaking

Kasahara, Seiji; Sato, Hiroyuki; Inagaki, Yoshiyuki; Ogawa, Masuro

Zairyo To Purosesu (CD-ROM), 25(2), p.647 - 650, 2012/09

Application of ACRES (Active Carbon Recycling Energy System) to steelmaking process is proposed for reduction of CO$$_{2}$$ emission and security of fossil fuel supply. ACRES is the concept of reuse of carbon element in CO$$_{2}$$ from fossil fuel usage by reducting to CO using non-fosssil primary energy. Selection of the primary energy and CO$$_{2}$$ reduction technology is important for the usability evaluation. High temperature gas-cooled reactor is a candidate of the energy, which can supply electricity, hydrogen and high temperature heat usable for CO$$_{2}$$ reduction. Technical examination on high temperature gas-cooled reactor as energy source of ACRES for steelmaking was carried out. Renewable solar energy is an also promising energy source. Here, ability of HTGR to follow load change was investigated and validated for parallel use of HTGR and solar energy.

Journal Articles

Beam position monitor system of J-PARC RCS

Hayashi, Naoki; Kawase, Masato; Hatakeyama, Shuichiro; Hiroki, Seiji; Saeki, Riuji; Takahashi, Hiroki; Teruyama, Yuzo*; Toyokawa, Ryoji*; Arakawa, Dai*; Hiramatsu, Shigenori*; et al.

Nuclear Instruments and Methods in Physics Research A, 677, p.94 - 106, 2012/06

 Times Cited Count:7 Percentile:43.25(Instruments & Instrumentation)

A beam position monitor (BPM) system at J-PARC RCS is described. The J-PARC RCS is a rapid-cycling proton synchrotron and its designed beam power is 1 MW. A diameter of the BPM detector is larger than 250 mm, however the system has to measure the beam position very accurately. The system should work not only for the high intensity but also for lower intensity. There are 54 BPM around the ring and most of them are placed inside steering magnets because of quite limited space. The BPM detector is an electro static type and it has four electrodes, and a pair of electrode gives a good linear response with diagonal cut shape to detect the charge center precisely. The signal processing unit, which is equipped with 14-bit 40 MSPS ADC and 600 MHz DSP, has been developed. They are controlled via shared memory space and EPICS. It is capable to record full 25 Hz pulse data for averaged mode and it could also store whole waveform data for further analysis, like turn-by-turn position calculation.

Journal Articles

A Phase-field simulation of uranium dendrite growth on the cathode in the electrorefining process

Shibuta, Yasushi*; Unoura, Seiji*; Sato, Takumi; Shibata, Hiroki; Kurata, Masaki*; Suzuki, Toshio*

Journal of Nuclear Materials, 414(2), p.114 - 119, 2011/07

 Times Cited Count:9 Percentile:35.08(Materials Science, Multidisciplinary)

The uranium dendrite growth on cathode during pyroprocessing of uranium is investigated using a novel phase-field model, in which electrodeposition of uranium and zirconium from molten-salt is taken into account. The threshold concentration of zirconium in molten salt demarcating the dendritic and planar growth is then estimated as a function of the current density. Moreover, growth process of both the dendritic and planar electrodeposits has been demonstrated by way of varying the mobility of the phase field, which consists of the effect of attachment kinetics and diffusion.

76 (Records 1-20 displayed on this page)