Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.
JAEA-Research 2019-013, 276 Pages, 2020/03
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.
Miyakawa, Kazuya; Aoyagi, Kazuhei; Sasamoto, Hiroshi; Akaki, Toshifumi*; Yamamoto, Hajime*
Proceedings of 5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future (YSRM 2019 and REIF 2019) (USB Flash Drive), 6 Pages, 2019/12
The construction and operation of geological repositories require excavation and ventilation of galleries, with significant groundwater drainage. Desaturation of rock around galleries is unavoidable and may affect hydraulic properties and redox conditions. This study used numerical modeling to assess the influence of dissolved gas on the degree of saturation of rock surrounding excavated galleries, focusing on siliceous mudstone rock in the 140 m, 250 m, and 350-m-deep galleries of the Horonobe Underground Research Laboratory, Japan. Based on previous electrical survey, the degree of saturation in the 250 m gallery was higher than that in the 140 m and 350 m galleries. In the Horonobe area, deep groundwater contains high concentrations of dissolved methane, and exsolution of this methane from pore water can affect desaturation. Simple numerical modeling, including simulation of multiphase flows, was undertaken for each gallery to confirm the effect of dissolved gas and rock permeability on desaturation. A sensitivity analysis was performed by varying dissolved gas contents and permeability. Results indicate that the dissolved gas content affects both the degree of saturation and its spatial extent, whereas rock permeability affects only the latter. Higher dissolved gas concentrations result in lower degrees of saturation with a greater spatial extent of desaturation, and higher permeability leads to greater extents of desaturation. It is therefore likely that gas content, rather than rock permeability, caused the observed variations in the saturation degree.
Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki; Aoyagi, Katsuhiro; Nomura, Kazutaka; Takada, Hiroshi
Journal of Physics; Conference Series, 1021(1), p.012085_1 - 012085_4, 2018/06
Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Aoyagi, Katsuhiro*; Muto, Hideki*; Nomura, Kazutaka*; Takada, Hiroshi; Ikeda, Yujiro
JAEA-Technology 2017-021, 75 Pages, 2017/08
Liquid hydrogen is employed as a cold neutron moderator material at the spallation neutron source of Materials and Life science experimental Facility of Japan Proton Accelerator Research Complex (J-PARC). From January 2015, it became observable that the differential pressure between heat exchangers and an 80 K adsorber (ADS) in a helium refrigerator system increased with operating time. In November 2015, the differential pressure rise became more significant, leading to degrade the refrigerating performance in cooling liquid hydrogen. In order to investigate the cause of the abnormal differential pressure rise between the heat exchangers and the ADS, we carried out visual inspection inside the heat exchangers and analyzed the impurities contained in the helium gas. Unfortunately, we could not identify the impurities causing the performance degradation, but observed a trace of oil in the inlet piping of the heat exchanger. Based on investigations of the abnormal events occurred in the refrigerators with similar refrigerating capacity at other facilities, we took measures that cleaning the heat exchangers with Freon and replacing the ADS with new one. As a result, the differential pressure rise phenomenon was removed to recover the performance. We have detected oil from the Freon used for cleaning the heat exchangers and at a felt supporting charcoal packed in the ADS. In particular, oil was accumulated in membranous form onto the felt at the entrance side in the ADS. The amount of oil contained in the helium gas was about 10 ppb or so, less than the design value, in the helium refrigerator. However, the oil accumulated onto the felt in the ADS through long operating period may cause abnormal differential pressure rise, leading to the performance degradation of the helium refrigerator. Further study is needed to specify the cause more clearly.
Aoyagi, Kazuhei; Kubota, Kenji*; Nakata, Eiji*; Suenaga, Hiroshi*; Nohara, Shintaro*
JAEA-Research 2017-004, 91 Pages, 2017/06
In this study, we performed seismic tomography, seismic refraction survey, resistivity tomography, and hydraulic tests to investigate the hydro-mechanical property of the excavation damaged zone (EDZ) in the 250 m gallery of the Horonobe Underground Research Laboratory. As a result of seismic tomography, seismic velocity is significantly decreased within 1 m from the gallery wall. The decrease of seismic velocity is related to the density of fracture induced around the gallery wall as a result of the gallery excavation. Thus the extent of the fractures induced by gallery excavation, i.e., EDZ fractures is clarified to be within 1.0 m from the gallery wall. The enhanced hydraulic conductivity was detected within 0.5 to 1.0 m from the gallery wall on the basis of the result of hydraulic tests. This is almost consistent with the extent of the region that seismic velocity is significantly decreased. Therefore, it is estimated that EDZ fractures induced around the gallery leads to the increase of hydraulic conductivity. In addition, the desaturation zone around the gallery is not induced as a result of resistivity tomography. From these results, the hydro-mechanical property of the EDZ is clarified in detail. Also, the in situ tests and evaluation method applied in this study are appropriate to investigate the EDZ in detail.
Sato, Toshinori; Sasamoto, Hiroshi; Ishii, Eiichi; Matsuoka, Toshiyuki; Hayano, Akira; Miyakawa, Kazuya; Fujita, Tomo*; Tanai, Kenji; Nakayama, Masashi; Takeda, Masaki; et al.
JAEA-Research 2016-025, 313 Pages, 2017/03
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formations at Horonobe, northern Hokkaido. This report summarizes the results of the Phase II investigations carried out from April 2005 to June 2014 to a depth of 350m. Integration of work from different disciplines into a "geosynthesis" ensures that the Phase II goals have been successfully achieved and identifies key issues that need to made to be addressed in the Phase II investigations Efforts are made to summarize as many lessons learnt from the Phase II investigations and other technical achievements as possible to form a "knowledge base" that will reinforce the technical basis for both implementation and the formulation of safety regulations.
Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Onoe, Hironori; Sato, Toshinori; Fujita, Tomo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Takeda, Masaki; Aoyagi, Kazuhei; et al.
JAEA-Review 2016-014, 274 Pages, 2016/08
We synthesized the research results from the Mizunami/Horonobe Underground Research Laboratories (URLs) and geo-stability projects in the second midterm research phase. This report can be used as a technical basis for the Nuclear Waste Management Organization of Japan/Regulator at each decision point from siting to beginning of disposal (Principal Investigation to Detailed Investigation Phase).
Hama, Katsuhiro; Mizuno, Takashi; Sasao, Eiji; Iwatsuki, Teruki; Saegusa, Hiromitsu; Sato, Toshinori; Fujita, Tomo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Yokota, Hideharu; et al.
JAEA-Research 2015-007, 269 Pages, 2015/08
We have synthesised the research results from Mizunami/Horonobe URLs and geo-stability projects in the second mid-term research phase. It could be used as technical bases for NUMO/Regulator in each decision point from sitting to beginning of disposal (Principal Investigation to Detailed Investigation Phase). High quality construction techniques and field investigation methods have been developed and implemented and these will be directly applicable to the National Disposal Program (along with general assessments of hazardous natural events and processes). It will be crucial to acquire technical knowledge on decisions of partial backfilling and final closure by actual field experiments in Mizunami/Horonobe URLs as main themes for the next phases.
Kaji, Yoshiyuki; Kondo, Keietsu; Aoyagi, Yoshiteru; Kato, Yoshiaki; Taguchi, Taketoshi; Takada, Fumiki; Nakano, Junichi; Ugachi, Hirokazu; Tsukada, Takashi; Takakura, Kenichi*; et al.
Proceedings of 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (CD-ROM), p.1203 - 1216, 2011/08
In order to investigate the effect of neutron dose rate on tensile property and irradiation assisted stress corrosion cracking (IASCC) growth behavior, the crack growth rate (CGR) test, tensile test and microstructure observation have been conducted with type 304 stainless steel specimens. The specimens were irradiated in high temperature water simulating the temperature of boiling water reactor (BWR) up to about 1dpa with two different dose rates at the Japan Materials Testing Reactor (JMTR). The radiation hardening increased with the dose rate, but there was little effect on CGR. Increase of the yield strength of specimens irradiated with the low dose rate condition was caused by the increase of number density of frank loops. Little difference of radiation-induced segregation at grain boundaries was observed in specimens irradiated by different dose rates. Furthermore, there was little effect on local plastic deformation behavior near crack tip in the crystal plasticity simulation.
Suzuki, Yoshio; Tatekawa, Takayuki; Kim, G.; Kino, Chiaki; Miyamura, Hiroko; Teshima, Naoya; Hayashi, Sachiko*; Aoyagi, Tetsuo; Takemiya, Hiroshi; Nakajima, Norihiro
Keisan Kogaku Koenkai Rombunshu, 15(2), p.1051 - 1054, 2010/05
We have developed the Atomic Energy Grid InfraStructure (AEGIS) for establishing computational infrastructure for nuclear field. In this R&D we have inherited the knowledge and skills in ITBL Infrastructure developed in the national project ITBL (Information Technology Based Laboratory), which aims at establishment of virtual research environment where supercomputers and data bases are connected by network. Here we have focused on two issues: improvements of safety and usability. For the safety, we have made the authentication mechanism double with both the personal certification and the machine certification. For the usability, we have developed the grid-enabled client API to use grid functions on a user terminal. By those R&Ds, we have successfully contributed to various nuclear researches, such as "full scale 3D vibration simulator for an entire nuclear power plant", "simulation for predicting quake-proof capability of nuclear power plants", and so on.
Maesako, Hiroshi*; Suzuki, Yoshio; Aoyagi, Tetsuo; Nakajima, Norihiro
Fujitsu, 55(2), p.109 - 115, 2004/03
ITBL (Information Technology Based Laboratory) project is promoted under the "e-Japan national priority program" by six research institutions. The project aims to construct a virtual laboratory which aid collaborative studies amongst researchers by allowing for sharing of intellectual properties and resources such as supercomputer hardware, software, data, etc. In order to realize this virtual laboratory environment, the Japan Atomic Energy Research Institute is developing an ITBL system infrastructure software system. Some of the highlighted functions offered by the ITBL infrastructure are: authentication for connecting to the supercomputers, parallel and distributed communication, job execution on the connected supercomputers, and formation of communities for aiding communication amongst researchers. In this passage, besides the introduction of the ITBL infrastructure, a brief introduction of the Quantum Bioinformatics and the Numerical Environmental Systems will be given as examples of the applications developed on the ITBL infrastructure.
Kitatsuji, Yoshihiro; Aoyagi, Hisao; Kimura, Takaumi; Yoshida, Zenko; Kudo, Hiroshi*; Kihara, Sorin*
Journal of Nuclear Science and Technology, 39(Suppl.3), p.259 - 262, 2002/11
Controlled-potential electrolysis (CPE) method for the transfer of an ion at the interface of two immiscible electrolyte solutions has been developed. The CPE method was applied to the transfer of actinide ions such as UO and Am between aqueous (W) and nitrobenzene (NB) solutions. The transfer of actinide ions from W to NB facilitated by bis(diphenyl-phosphoryl)methane (BDPPM) was studied, and it was found that CPE was successfully applied to the electrolytic separation of U(VI) and Am(III) from W to NB containing BDPPM.
Kawai, Mikito; Aoyagi, Tetsuo; Ohara, Hiroshi; Honda, Atsushi; Ito, Takao; Kuriyama, Masaaki
Proc. of 17th IEEE/NPSS Symposium Fusion Engineering (SOFE'97), 1, p.531 - 534, 1998/00
no abstracts in English
Kawai, Mikito; Aoyagi, Tetsuo; Ohara, Hiroshi; Honda, Atsushi; Kuriyama, Masaaki
JAERI-Tech 97-012, 69 Pages, 1997/03
no abstracts in English
Watanabe, Kazuhiro; ; Aoyagi, Tetsuo; ; Fujiwara, Yukio; Honda, Atsushi; Inoue, Takashi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; et al.
Radiation Physics and Chemistry, 49(6), p.631 - 639, 1997/00
no abstracts in English
Kuriyama, Masaaki; Aoyagi, Tetsuo; ; *; Ito, Takao; Inoue, Takashi; Usami, H*; Usui, Katsutomi; ; Oshima, Katsumi*; et al.
Nihon Genshiryoku Gakkai-Shi, 38(11), p.912 - 922, 1996/00
no abstracts in English
Fujii, Tsuneyuki; Kimura, Haruyuki; Saigusa, Mikio; Akiba, Masato; Ando, Toshiro; ; Aoyagi, Tetsuo; ; Azumi, Masafumi; Fukuda, Takeshi; et al.
Plasma Physics and Controlled Nuclear Fusion Research 1988, Vol.1, p.605 - 610, 1989/00
no abstracts in English
Nakatani, Takeshi; Inamura, Yasuhiro; Ito, Takayoshi; Kajimoto, Ryoichi; Aoyagi, Tetsuo; Ohara, Takashi; Otomo, Toshiya*; Yasu, Yoshiji*; Suzuki, Jiro*; Morishima, Takahiro*; et al.
no journal, ,
We have started the commissioning of the neutron scattering experiment instruments since May 2008 in MLF, J-PARC. Simultaneously, we have started the commissioning of the data acquisition and analysis software. Experimental users operate this software through the software framework which we have developed. The software framework was developed based on Python which is an object oriented script language. The system implemented with the software framework can seamlessly measure, analyze and visualize with some modules which are experimental control and data analysis. In this presentation, we report the process of the construction and the current status of the software.
Nakajima, Kohei; Suzuki, Yoshio; Aoyagi, Tetsuo; Takemiya, Hiroshi
no journal, ,
We propose that the new approach to use safely and easily the data output by the experimental facility and the parallel computer. In addition, experimentation results are also reported in the case of handle the huge simulation data output by PC cluster.
Nakatani, Takeshi; Inamura, Yasuhiro; Ito, Takayoshi; Kajimoto, Ryoichi; Harjo, S.; Arai, Masatoshi; Ohara, Takashi; Nakagawa, Hiroshi; Aoyagi, Tetsuo; Otomo, Toshiya*; et al.
no journal, ,
We have developed the software framework in MLF computing environment from 2006 to 2008. The software framework is the fundamental software for neutron and muon experimental instruments in J-PARC/MLF. Currently, the software framework is installed at 4D Space Access Neutron Spectrometer (BL01), IBARAKI Biological Crystal Diffractometer (BL03), Cold-Neutron Disk-Chopper Spectrometer (BL14), Engineering Materials Diffractometer (BL19) and High Intensity Total Diffractometer (BL21). The features of experimental control, analysis, visualization and authorization are already implemented in the software framework. In this year, we will start the development to introduce the feature of database. We will present the current status and future plan of the software framework.