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Journal Articles

Study on structural integrity assessment of reactor pressure vessel based on three-dimensional thermal-hydraulics and structural analyses

Katsuyama, Jinya; Katsumata, Genshichiro; Onizawa, Kunio; Watanabe, Tadashi*; Nishiyama, Yutaka

Proceedings of 2014 ASME Pressure Vessels and Piping Conference (PVP 2014) (DVD-ROM), 9 Pages, 2014/07

For structural integrity assessment on reactor pressure vessel (RPV) of pressurized water reactor during the pressurized thermal shock (PTS) events, temperature of coolant water and heat transfer coefficient between coolant water and RPV are dominant factors. These values can be determined on the basis of thermal-hydraulics (TH) analysis simulating PTS events. Using these values, structural integrity assessment of RPV is performed by thermal-structural analysis, e.g. loading that affects the crack initiation and propagation is evaluated. In this study, we performed the TH and thermal-structural analyses using three-dimensional model of cold-leg, downcomer and RPV to assess loading conditions during the PTS more accurate. We obtained the loading histories at the reactor core region of RPV where a crack is postulated in the structural integrity assessment. Through the comparison between analysis results and current evaluation method, conservatism of current method will be discussed.

Journal Articles

The Proposals relevant to seepage flow simulation in rockmass around tunnel under unsaturated condition; Method for estimating unsaturated seepage parameters of stones and setting of boundary condition on tunnel wall

Imai, Hisashi*; Amemiya, Kiyoshi*; Matsui, Hiroya; Sato, Toshinori; Saegusa, Hiromitsu; Watanabe, Kunio*

Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 69(3), p.285 - 296, 2013/07

The more accurate understanding and appropriate control of unsaturated area around tunnel excavated in deep rock-mass are required, for the geological isolation of radioactive waste project and also underground rock cavern storage project of liquefied petroleum gas. The numerical simulation of seepage flow is usually conducted to understand and evaluate the unsaturated zone around tunnel. The unsaturated parameters (such as moisture characteristic curve and relative permeability) and appropriate control of boundary condition are indispensable for the simulation. Authors developed methodology to measure unsaturated parameters utilizing the measuring method conventionally applied to soils and showed the efficiency of the method via a laboratory experiment. The idea of combining seepage face condition and flow rate fixed condition was derived, and the efficiency was shown in an model simulation. The two developments enabled the accurate estimation and understanding the evolution of unsaturated zone around tunnel.

Journal Articles

Molecular and carbon isotope compositions of hydrocarbon gas in Neogene sedimentary rocks in Horonobe area, northern Hokkaido, Japan

Funaki, Hironori; Ishiyama, Koji*; Waseda, Amane*; Kato, Susumu*; Watanabe, Kunio*

Chigaku Zasshi, 121(6), p.929 - 945, 2012/12

Molecular and carbon isotope compositions of hydrocarbon gas have information related to their generation, migration and accumulation, and serve evaluations of gas permeability in sedimentary rocks. We conducted headspace gas analysis at the cores (below 500 m depth) to evaluate gas permeability in Neogene sedimentary rocks in the Horonobe, Hokkaido, Japan. As a result, it was shown that hydrocarbon gases were almost biogenic methane. Further analysis of these data indicated that concentration and carbon isotope of methane varied carbon isotopic fractionation during anaerobic microbial oxidation and migration near the faults. A formation of high concentration and light carbon isotope of methane at present in the study area is low gas permeability and is less affected by secondary post-generic process.

JAEA Reports

Interdisciplinary approach to improve and systematize the investigation and evaluation techniques on geological environment in relation to radioactive waste repository; Japanese fiscal year, 2010 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2011-033, 126 Pages, 2012/02

JAEA-Research-2011-033.pdf:31.33MB

The next advancements for the research of radioactive waste repository was started to improve and systematize the investigation and evaluation techniques on geological environment in consideration of intra-field of science and technology. Intra-field means the various fields among each study area of (a) geological environment, (b) design and engineering, (c) safety evaluation for radioactive waste repository, here. The following items were studied and discussed this year. (1) To Reconstruct Near Field (NF) Concept in consideration of coupled phenomena on geological environment. (2) To develop systematic investigation techniques on the geological environment in consideration of intra-field among each study area above mentioned (a), (b) and (c). Regarding (1), examination of NF concept focused on the realistic crystalline rock was carried out. Also through the overall discussion in the committee, comments from the all commissioners in relation to the intra-field of their study area were made to reflect on reconstruction of NF concept. Regarding (2), the research and development in consideration of NF and intra-field among each study area were conducted.

JAEA Reports

Study on systemizing of technology for investigation and analysis of the deep underground geological environment; Japanese fiscal year, 2009 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2010-049, 282 Pages, 2011/02

JAEA-Research-2010-049.pdf:29.88MB

This report summarizes studies that have been carried out with the aim of assessing and systemizing the technology used for the investigation and analysis of the deep underground geological environment in relation to the disposal of radioactive waste. The main studies were: (1) a study on the research and development (R&D) topics proven to have practical application for the investigation, and analysis and understanding of the deep underground geological environment, and, (2) a study on leading edge technology that can provide the advanced technical basis for the investigation, analysis and understanding of the deep underground geological environment. Regarding the R&D topics (1, above), specific investigations, measurements, numerical analyses and chemical analyses were performed and reviewed with respect to the topics, (a) Repository design, engineering technology (b) Geological environment and (c) Safety evaluation. Based on the result of the review, topics requiring collaboration research in overlapping research fields, including safety assessment, were identified. Also, the near field concept (NFC) was reconsidered in terms of its realistic construction model. Regarding advanced technology (2, above), based on the objectives of the JAEA (Japan Atomic Energy Agency) research project, the study was implemented considering previous R&D results and detailed research result at the research site and thus an assessment of the need for advanced technical basis for investigation and analysis. This study contributed to the R&D development and its practical application.

JAEA Reports

Study on systemizing of technology for investigation and analysis of the deep underground geological environment; Japanese fiscal year 2008 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2009-055, 145 Pages, 2010/02

JAEA-Research-2009-055.pdf:55.53MB

This report summarizes studies that were carried out with the aim of assessing and systemizing the technology used for the investigation and analysis of the deep underground geological environment in relation to the disposal of radioactive waste. The main studies were: (1) a study on the research and development (R&D) topics proven to have practical application for the investigation, analysis and understanding of the deep underground geological environment, and, (2) a study on leading edge technology that can provide the advanced technical basis for the investigation, analysis and understanding of the deep underground geological environment. The principal results obtained from the studies are as follows: Regarding the R&D topics (1, above), the specific investigations, measurements, numerical and chemical analyses were reviewed with respect to engineering technology and the geological environment in this year. Based on the results of the review, topics requiring collaboration research in overlapping research fields, including safety assessment, were identified. Also, the near field concept (NFC) was reconsidered in terms of both the generic model and for crystalline rock. Regarding advanced technology (2, above), based on the objectives of the JAEA (Japan Atomic Energy Agency) research project, the study was implemented considering previous R&D results and detailed research result at the research site and thus an assessment of the need for advanced technical basis for investigation and analysis. This study contributed to the R&D development and its practical application.

Journal Articles

Prediction of pore pressure change due to the shaft excavations using artificial intelligent techniques

Takeuchi, Shinji; Chinone, Tatsuya*; Mebruck, N.*; Watanabe, Kunio*

Sui Kogaku Rombunshu (CD-ROM), 54, p.409 - 414, 2010/02

Tunnel or shaft excavation in fractured rock mass brings out the pore pressure change around the site. The effect of the construction is spatially different due to the existence of high permeable fractures around the site. The precise prediction with real time of pore pressure change is very important to maintain the groundwater in good condition. In this paper, pore pressure measured by 50 sensors which was installed in 5 boreholes around two shafts that are now under construction for Mizunami underground research laboratory project of JAEA, was analysed by using Genetic Algorithm (GA) and Artificial Neural Network (ANN). It was found that the pore pressure change in this area could be divided into four patterns. The pore pressure fluctuation at an arbitrary point was precisely predicted on real time with pore pressure data obtained at other sections when the fluctuation patterns of those data are identical.

JAEA Reports

Study on reciprocal relation of pore water pressure with genetic algorithm and neural network model(Contract research)

Seno, Shoji*; Kunimaru, Takanori; Nakajima, Makoto*; Toida, Masaru*; Watanabe, Kunio*; Sohail, A. R.*

JAEA-Research 2008-126, 120 Pages, 2009/12

JAEA-Research-2008-126.pdf:29.29MB

At first, to exclude the influences of working of nature such as tide and atmospheric pressure from the source data, an analysis with Bayesian model was progressed. As the result of the estimation of these influences calculated by BAYTAP-G (Bayesian Tidal Analysis Program Grouping Model), it was found that the influence of the atmospheric pressure was comparatively large and that of tide was comparatively small.

JAEA Reports

Study on systemizing technology on investigation and analysis of deep underground geological environment; Japanese fiscal year, 2007 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2008-099, 171 Pages, 2009/03

JAEA-Research-2008-099-1.pdf:28.65MB
JAEA-Research-2008-099-2.pdf:49.14MB

In this year, the following studies were carried out with the aim of systemizing the technology on the investigation and analysis to understand the deep underground geological environment in relation to the radioactive waste disposal. (1) The study on the research and development (R&D) subjects which turned to the practical investigation and analysis of deep underground geological environment. (2) The study on the advanced technical basis for the investigation and analysis of deep underground geological environment. The results obtained from the studies are as follows: Regarding (1), the specific investigations, measurements, numerical and chemical analyses were performed particularly for research subjects: (a) the repository design and engineering technology and (b) geological environment. Based on the results on (1), (c) tasks of collaboration research on niche area between the research fields, including the safety assessment field, were selected. Also subject's items of the NFC (Near Field Concept) redefinition were discussed. Regarding (2), based on the extraction tasks of JAEA (Japan Atomic Energy Agency) research project, the study was implemented with applying previous R&D results and detailed research at the research field was carried out. This study contributed to the R&D development for its practical application.

Journal Articles

Evaluation of uncertainties originating from the different modeling approaches applied to analyze regional groundwater flow in the Tono area of Japan

Ijiri, Yuji*; Saegusa, Hiromitsu; Sawada, Atsushi; Ono, Makoto*; Watanabe, Kunio*; Karasaki, Kenji*; Doughty, C.*; Shimo, Michito*; Fumimura, Kenichi*

Journal of Contaminant Hydrology, 103(3-4), p.168 - 181, 2009/01

 Times Cited Count:7 Percentile:27.71(Environmental Sciences)

Qualitative evaluation of the effects of uncertainties originating from scenario development, conceptual models, and parameter values is an important subject in the area of safety assessment for high-level nuclear waste disposal. In this study, regional-scale groundwater flow analyses for the Tono area, Japan were conducted using three continuous models which were designed to handle heterogeneous porous media. We evaluated the simulation results to quantitatively analyze uncertainties originating from conceptual models. We found that uncertainties originating from conceptual models (1) greatly depend on boundary conditions and hydrological structures to be modeled, which are assigned by modelers, and (2) are larger than uncertainties originating from the variance in realizations of the Monte Carlo method in stochastic modeling.

Journal Articles

Classification of water level fluctuation data in wells using linear regression models and genetic algorithm

Wakamatsu, Naonori*; Watanabe, Kunio*; Takeuchi, Shinji; Saegusa, Hiromitsu

Oyo Chishitsu, 49(3), p.126 - 138, 2008/08

A method to evaluate similarities of water level fluctuation between wells is proposed. Linear regression models with independent variable for meteorological condition such as rainfall and atmospheric pressure etc. are developed, and well similarity is estimated from model parameters (regression coefficients and model fitness) calculated by Genetic Algorism. The method was applied to the twelve wells in Tono area, central Japan. Although groundwater level fluctuation is primarily affected by rainfall and pumping conditions, different geological conditions would cause different types of water level response to the factors. Models using preceding rainfalls and atmospheric pressure and models using water level in other wells suggested that water level fluctuation data of the wells are classified into groups which reflect difference in pressure propagation for rain infiltration among the geological units.

JAEA Reports

Study on systemizing technology on the investigation and analysis of deep underground geological environment; Japanese fiscal year, 2006 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2008-042, 236 Pages, 2008/04

JAEA-Research-2008-042.pdf:23.43MB

The following study was done with the aim of systemizing the technology on the investigation and analysis to grasp deep underground geological environment in relation to the radioactive waste disposal. (1) The study on the research and development (R&D) subjects which turned to the practical investigation and analysis of deep underground geological environment. (2) The study on the advanced technical basis of the investigation and analysis of deep underground geological environment. It continued in the former year and got the following results. Concerning (1), the concrete investigation, measurements, numerical analyses and chemical analyses were enforced about the following item and extracted some subjects with the viewpoint of radioactive waste disposal. Concerning (2), the evaluation of the results and a way to the practical use were discussed on the R&D activities of the following item. The R&D activities of the study group concerning (2) are related to the fundamental and elemental technology. It was discussed if these results could be taken into the practical investigation programs which characterize the geological environment and engineering technology in the Tono Geoscience Center. The Study group also discussed and gave the comment on the 2nd phase (the shaft construction phase of the MIU (Mizunami Underground Research Laboratory) research program in the JAEA.

JAEA Reports

Study on systemizing the technology on the investigation and analysis of deep underground geological environment; Japanese fiscal year, 2006 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2007-060, 210 Pages, 2007/09

JAEA-Research-2007-060-1.pdf:43.82MB
JAEA-Research-2007-060-2.pdf:41.2MB
JAEA-Research-2007-060-3.pdf:6.42MB

The following study was done with the aim of systemizing the technology on the investigation and analysis to grasp deep underground geological environment in relation to the radioactive waste disposal. (1) The study on the research and development (R&D) subjects which turned to the practical investigation and analysis of deep underground geological environment. (2) The study on the advanced technical basis of the investigation and analysis of deep underground geological environment. It continued in the former year and got the following results. Concerning (1), the concrete investigation, measurements, numerical analyses and chemical analyses were enforced about the following item and extracted some subjects with the viewpoint of radioactive waste disposal. More over, the way to make the co-operative program among each field of the following (a), (b) and (c) was discussed. (a) The subjects extracted with the viewpoint of the repository design and engineering technology. (b) The subject extracted with the viewpoint of the safety assessment. (c) The subjects extracted with the viewpoint of the geological environment. The joint research subjects among each field of (a), (b), (c) were also discussed. Concerning (2), the evaluation of the results and a way to the practical use were discussed on the R&D activities. The Study group also discussed and gave the comment on the 2nd stage of the MIU (Mizunami Underground Research Laboratory) research program in the JAEA.

Journal Articles

${it In situ}$ hydraulic tests in the active fault survey tunnel, Kamioka mine, excavated through the active Mozumi-Sukenobe fault zone and their hydrogeological significance

Nohara, Tsuyoshi; Tanaka, Hidemi*; Watanabe, Kunio*; Furukawa, Noboru*; Takami, Akira*

Island Arc, 15(4), p.537 - 545, 2006/12

 Times Cited Count:3 Percentile:11.96(Geosciences, Multidisciplinary)

The spatial hydrogeological and structural character of the active Mozumi-Sukenobu Fault (MSF) was investigated along a survey tunnel excavated through the MSF in the Kamioka Mine, Central Japan. Major groundwater conduits on both sides of the MSF are recognized. One is considered to be a sub-vertical conduit between the tunnel and the surface, the other is estimated to be a major reservoir of old meteoric water alongside the MSF. Studies indicate that part of the MSF is a sub-vertical continuous barrier that obstructs younger meteoric water observed in the southeastern part of the Active Fault Survey Tunnel (AFST) and recharge to the rock mass intersected by the northwestern part of the AFST. It is considered that the MSF is a continuous barrier resulting in the storage of a large quantity of older groundwater to the northwest. The observations indicate that the major reservoir is not the fault breccia associated with the NE-SW oriented faults of the MSF. Rather, the reservoir is considered to be the zone in which blocks of fractured rocks occur beside high angle faults corresponding to X shears that coincide in orientation with the present-day regional stress field and antithetic Riedel shears of the MSF. It is considered that secondary porosity is developed in the major reservoir by the destruction of filling minerals and fracture development beside these shears. The results of borehole investigations in the AFST indicate that increase in hydraulic conductivity is not directly related to increased density of fractures around the MSF. Our results suggested that minor conduits are sporadically distributed in the sedimentary rocks around the MSF in the AFST.

Journal Articles

Stream flow forecasting by artificial neural network (ANN) model trained by real coded genetic algorithm (GA); A Case study when role of groundwater flow component in surface runoff is small

Sohail, A. R.*; Watanabe, Kunio*; Takeuchi, Shinji

Chikasui Gakkai-Shi, 48(4), p.233 - 262, 2006/11

Runoff analysis for precise prediction of discharge was carried out by artificial neural network model with real coded genetic algorithm (GAANN), back propagation artificial neural network model (BPANN) and multivariate autoregressive moving average model (MARMA). It was found that for very small catchments seasonal effect on the runoff is dominant. It was also found that estimation by ANN models was better than MARMA model for analyzing the responses to intense rainfalls in summer. The accuracy of the forecasts after several time periods in future was also investigated and found to decrease as time period is increased.

JAEA Reports

Study on Sysytemizing the Technology on the Investigation and Analysis of Deep Underground Geological Environment, 2005.

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Eichi*

JNC TJ7400 2005-081, 337 Pages, 2005/02

JNC-TJ7400-2005-081.pdf:39.72MB

The following study was done in this year with the aim of syatemizing the technology on the investigation and analysis to grasp deep underground geological environment in relation to the radioactive waste disposal. The study to extract the research and development (R&D) subjects turned to the practical investigation and analysis of deep undergruound geological environment. The study on the advanced technical basis of the investigation and analysis of deep underground geological environment.

JAEA Reports

Study on Geological and Hydrogeological Modeling in Fractured Rock Masses

Osada, Masahiko*; Watanabe, Kunio*

JNC TJ7400 2005-033, 176 Pages, 2004/03

JNC-TJ7400-2005-033.PDF:7.11MB

This research is high, and what of the possibility forming water Michi aiming to develop the modeling technique of geologic structure/Mizcotowari geological features structure examined about Step structure the main crack system.

JAEA Reports

Study on Systemizing the Technology on the Investigation and Analysis of Deep Underground Geological Environment, 2003

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*

JNC TJ7400 2004-008, 234 Pages, 2004/02

JNC-TJ7400-2004-008.pdf:11.02MB

The following was done in this year with the aim of systemizing the technology on the investigation and analysis to grasp deep underground geological environment in relation to the radioactive waste disposal. (1) The study to extract the research and development (R&D) subjects turned to the practical investigation and analysis of deep underground geological environment. (2) The study on the advanced technical basis of the investigation and analysis of deep underground geological environment. It continued in the former year and got the following results. Concerning (1), the concrete investigation, measurement and numerical / chemical analysis were enforced about the following item and extracted some subjects with the viewpoint of radioactive waste disposal. 1: The subjects extracted with the viewpoint of the repository design and engineering technology. *The evaluation technique of the excavation disturbed zone (EDZ) by acoustic emission (AE) or micro seismicity measurement. *Fracture sealing technique such as vibration grouting toward low permeable rock mass. 2: The subject extracted with the viewpoint of the safety assessment. *Precipitation of the metal hydroxide (non-crystallized) through migration process in rock mass and change to the crystallized oxide.3: The subjects extracted with the viewpoint of the geological environment. *Fracture distribution characteristics around the fault, it can think to meet in the underground facilities and the prediction of long term activities of the fault. *Natural sealing process by the secondary filling materials (iron oxide and carbonate etc.) in the fracture of rock mass and that influence which may be given to the long-term migration and release of nuclides. The advanced research subjects among the each field of 1, 2, 3 were also discussed. Concerning (2), the evaluation of the results and a way to the practical use were discussed on the R&D activities of the following item.

JAEA Reports

A Stydy of Groundwater Monitoring Data Analysis Using Artifical Neural Network Model

Watanabe, Kunio; Gautam, M. R.*; Saegusa, Hiromitsu

JNC TY7400 2003-002, 68 Pages, 2003/05

JNC-TY7400-2003-002.pdf:2.32MB

The results of groundwater flow modeling are to be justified using groundwater monitoring data in the hydrogeological characterization. On the other hand, hydraulic continuities of the geological structures, all of which are considered to have great effect on groundwater flow and/or groundwater quality, are to be estimated using the groundwater flow monitoring data with hydraulic response to some impacts such as borehole drilling, pumping test and so on. Therefore, the groundwater monitoring is important for characterizing the geological and hydrogeological environments. In order to characterize of hydrogeological environment using the monitoring data, it is important to evaluate the influence of artifical and natural impact on the monitoring data. In this study, the following three research works were carried out based on the groundwater monitoring data collected at the Tono area. Artifical Neural Network (ANN) was adopted as the tool for monitoring data analysis.Runoff analysis for assessment of importance of soil moisture on runoff estimation in a catchment Analysis of water level fluctuation for determination influence factors in the water level fluctuation and for filtering out the influence factors from the water level data Analysis of hydraulic pressure fluctuation in deep geological formations for hydrogeological characterization and assessment of human influence on the pore pressure in deep formation Through this study, applicability of ANN for analysis and interpretation of the groundwater monitoring data could be confirmed and methodology for utilization the monitoring data for understanding and characterization of hydrogeological environment could be developed.

JAEA Reports

A study on Geological Modeling for Fractured Rock (2)

Osada, Masahiko*; Watanabe, Kunio*

JNC TJ7400 2005-025, 203 Pages, 2003/03

JNC-TJ7400-2005-025.pdf:18.42MB

The purpose of this study is to develop how to model the fractures that act as the major conduits of groundwater.

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