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Motoshima, Takayuki*; Koike, Masashi*; Hagihara, Takeshi*; Aoyagi, Kazuhei
Dai-46-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.208 - 213, 2019/01
The short step construction method is the standard construction method for deep shaft excavation. However, considering the shaft construction in the sedimentary rock widely distributed in Japan, the support concrete stress can become excessive especially when there are bad conditions such as low rock strength, anisotropic initial stress, or high ground pressure. In this research, we introduced the dual support design to the short step construction method in order to reduce the support stress, and confirmed the validity by three dimensional numerical analysis. Validation analysis was conducted using the in-situ data in the Horonobe Underground Research Project conducted by Japan Atomic Energy Agency.
Aoyagi, Kazuhei; Kamemura, Katsumi*; Sugawara, Kentaro*; Hagihara, Takeshi*
Dai-53-Kai Jiban Kogaku Kenkyu Happyokai Happyo Koenshu (DVD-ROM), p.11 - 12, 2018/07
no abstracts in English
Kamemura, Katsumi*; Aoyagi, Kazuhei; Nago, Makito*; Sugawara, Kentaro*
Dai-45-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.43 - 48, 2018/01
In situ stress state is very important for the design of deep underground facility of high-level radioactive waste disposal repository. This study establishes a practical and effective method for estimating in situ stress state based on the measured convergence and detailed geological observations during gallery excavation. The convergence was measured in various directions of the loop gallery at 350m depth of the Horonobe URL; this allows determination of the stress state corresponding to the rock mass behavior in 120m 
200m area. In situ stress state estimated by the back analysis considering existing faults and fractures showed a good agreement with that of estimated from hydraulic fracturing method.
Igarashi, Sayaka*; Sakamoto, Shigehiro*; Ugata, Takeshi*; Nishida, Akemi; Muramatsu, Ken*; Takada, Tsuyoshi*
Transactions of the 24th International Conference on Structural Mechanics in Reactor Technology (SMiRT-24) (USB Flash Drive), 10 Pages, 2017/08
For the purpose of improving the precision of probabilistic seismic PRA for NPPs, the authors developed the methodology for generating hazard-consistent ground motions based on stochastic fault models which include seismic-source uncertainties by Monte Carlo Simulation. The PRA with HCGMs would require a lot of computer power. The optimization of ground-motions generations is one of the most important subjects for practical application of the PRA method. For optimizing the ground-motions generations, seismic sources for the generations should be selected effectively, and this can be conducted by utilizing optimal seismic index in the hazard analysis. In this study, the method for detecting the optimal seismic intensity index which corresponds with damage probabilities of the target equipment system was developed, and the validity of the proposed method was confirmed for some equipment systems, which has different weak equipment with each other.
Nago, Makito*; Motoshima, Takayuki*; Miyakawa, Kazuya; Kanie, Shunji*; Sanoki, Satoru*
Proceedings of ITA-AITES World Tunnel Congress 2017 (WTC 2017) (USB Flash Drive), 10 Pages, 2017/06
This study presents a new approach to increase construction safety under methane inflow conditions by providing the three-dimensional concentration distribution of methane in underground structures. The study was conducted at the Horonobe Underground Research Laboratory, which is located in Neogene sedimentary rock where groundwater contains dissolved methane. As conventional gas sensors are confined to measurement at a single point in time and space, a new system was developed combining a laser methane detector and a laser range finder to effectively obtain the spatial concentration distribution of methane. This system was tested in tunnel galleries located at a depth of 350 m. The results show that this system is effective for identifying unpredicted methane emissions as well as predicted emission hotspots and for examining the validity of the ventilation scheme, which ensures construction safety.
Aoyagi, Kazuhei; Kamemura, Katsumi*; Nago, Makito*; Sugawara, Kentaro*; Matsubara, Makoto*
Proceedings of ITA-AITES World Tunnel Congress 2017 (WTC 2017) (USB Flash Drive), 10 Pages, 2017/06
An in situ stress state is one of the important factors in the design of deep underground facility of high-level radioactive waste disposal repository. This study establishes a practical and effective method for estimating in situ stress state on the basis of the measured convergence during gallery excavation. The convergence was measured in various directions of the loop gallery at 350m depth of the Horonobe Underground Research Laboratory; this allows determination of the stress state corresponding to the rock mass deformation behavior in an approximately 120 m* 200 m area. To estimate in situ stress state around that area, a back analysis method considering the existence of faults and fractures around the gallery was developed. The analyzed results showed a good agreement with the trend of in situ stress state estimated from hydraulic fracturing method.
Kamemura, Katsumi*; Aoyagi, Kazuhei; Nago, Makito*; Sugawara, Kentaro*; Matsubara, Makoto*
Dai-14-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), 6 Pages, 2017/01
In the design of deep underground structures such as high-level radioactive waste disposal repositories, the estimation of rock mass stress state is important as well as the estimation of mechanical characteristics of rock mass. This study establishes a practical and effective method for estimating in situ stress based on the convergence measurement results obtained during gallery construction of URL. The convergence was measured in various directions of the URL loop gallery at 350 m depth, and this will allow determination of the stress state over a large area using a back analysis method. In order to improve the accuracy of initial stress estimation, the relationship between convergence measurement results and geological situation of existing fractures were studied. The analysis results show good agreement with the in situ stress state results reported in previous studies and confirm the applicability of the proposed method.
Nishida, Akemi; Igarashi, Sayaka*; Sakamoto, Shigehiro*; Uchiyama, Yasuo*; Yamamoto, Yu*; Muramatsu, Ken*; Takada, Tsuyoshi*
Nuclear Engineering and Design, 295, p.875 - 886, 2015/12
Times Cited Count：2 Percentile：17.57(Nuclear Science & Technology)Most probabilistic risk assessments (PRA) of structures involve the use of probabilistic schemes such as the scheme using probabilistic seismic hazard and fragility curves. Even when earthquake ground motions are required in Monte Carlo Simulations (MCS), they are generated to fit the specified response spectra, such as uniform hazard spectra at a specified exceedance probability. These ground motions, however, are not directly linked with corresponding seismic source characteristics. In this paper, the authors propose a methodology based on MCS to reproduce a set of input ground motions to develop an advanced PRA scheme that can explain the exceedance probability and sequence of functional loss in a nuclear power plant. These generated motions are consistent with the seismic hazard for the target site and their seismic source characteristics can be recognized in detail.
Nishida, Akemi; Igarashi, Sayaka*; Sakamoto, Shigehiro*; Muramatsu, Ken; Takada, Tsuyoshi*
Dai-8-Kai Kozobutsu No Anzensei, Shinraisei Ni Kansuru Kokunai Shimpojiumu (JCOSSAR 2015) Koen Rombunshu (CD-ROM), p.108 - 113, 2015/10
Research and development on next-generation seismic probabilistic risk assessment by using 3D vibration simulators is ongoing to evaluate the seismic safety performance of nuclear plants with high reliability. Most structural PRA uses probabilistic schemes such as the scheme that uses probabilistic seismic hazard and fragility curves. Even when earthquake ground motions are required in Monte Carlo Simulations (MCS), they are generated to fit the specified response spectra, such as uniform hazard spectra at a specified exceedance probability. However, these ground motions are not directly linked with their corresponding seismic source characteristics. In this context, the authors propose a methodology based on MCS to reproduce a set of input ground motions to develop an advanced PRA scheme. This paper describes the methodology to reproduce a set of input ground motions briefly and the analytical results of a nuclear plant building and equipment using the set of input ground motions.
Igarashi, Sayaka*; Sakamoto, Shigehiro*; Nishida, Akemi; Muramatsu, Ken; Takada, Tsuyoshi*
Dai-8-Kai Kozobutsu No Anzensei, Shinraisei Ni Kansuru Kokunai Shimpojiumu (JCOSSAR 2015) Koen Rombunshu (CD-ROM), p.535 - 541, 2015/10
In this study, building function loss induced by hazard-consistent ground motions (HCGMs), which are consistent with seismic hazard of the reference site and are associated with seismic source characteristics, was evaluated in order to confirm the influence by the variance and/or inter-period correlation of response spectra of ground motions on the resulted damage probabilities of equipment system. Firstly, the statistics values of the response spectra of HCGMs were evaluated, and 3 cases of simulated ground-motions sets are generated so that they fit to the median response spectra of HCGMs. The authors conducted structural response analysis with these ground motions set, and calculated annual damage frequency of equipment system. As a result, it was found that the variance of response spectra was more important factor on damage probability evaluation of systems than inter-period correlation.
Igarashi, Sayaka*; Sakamoto, Shigehiro*; Uchiyama, Yasuo*; Yamamoto, Yu*; Nishida, Akemi; Muramatsu, Ken; Takada, Tsuyoshi*
Transactions of the 23rd International Conference on Structural Mechanics in Reactor Technology (SMiRT-23) (USB Flash Drive), 10 Pages, 2015/08
In the preceding study, the methodology to generate ground-motion time histories for advanced PRA of NPPs was proposed by Nishida et al.. They are consistent with seismic hazard at reference site, and incorporate uncertainties of seismic-source characteristics. The ground motions utilized in conventional PRA are generated to fit to specified spectra such as UHS, and they are often generated without considering the variation of spectra. Even if it is considered, their inter-period correlations are generally assumed to be 1.0. In this paper, the authors prepared some cases of ground-motions sets. Ground motions are generated to fit to the response spectra calculated from hazard-consistent ground motions. While the target response spectra have the same median for all case, they have different variation and inter-period correlation. The response analyses of general RC structure and PWR building are conducted and the damage frequencies of simplified equipment system are compared.
Igarashi, Sayaka*; Sakamoto, Shigehiro*; Nishida, Akemi; Muramatsu, Ken; Takada, Tsuyoshi*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 10 Pages, 2015/05
In the preceding study, the ground-motion time histories consistent with seismic hazard were generated by Nishida et al.. In this study, structural response analyses of general RC structure are conducted with the 2,736 waves of ground motions which were generated from one seismic source, minami-kanto earthquakes. These ground motions incorporate the differences of their seismic-source characteristics. The multi-regression analyses are also conducted with the results of response analysis. As a result, the seismic moment, stress drop and Q-value coefficient showed clear positive correlation with seismic intensities and maximum structural responses. This can be expressed by the relationship between the Fourier spectra of seismic source and seismic-source characteristics. On the other hand, asperity location showed negative correlation with seismic intensities and maximum structural responses. The trend can be expressed by the relationship of location between reference site and faults.
Ijiri, Yuji*; Noda, Masaru*; Nobuto, Jun*; Matsui, Hiroya; Mikake, Shinichiro; Hashizume, Shigeru
JAEA-Technology 2013-047, 819 Pages, 2014/03
JAEA-Technology-2013-047-01.pdf:41.49MBJAEA-Technology-2013-047-02.pdf:25.26MB
The researches on engineering technology in the Mizunami Underground Research Laboratory plan consists of (1) research on engineering technology at a deep underground, and (2) research on engineering technology as abasis of geological disposal. The former research mainly aimed in this study are categorized in (a) development of design and construction planning technologies, (b) development of construction technology, (c) development of countermeasure technology, (d) development of technology for security. In this study, the researches on engineering technology are proceeded in these four categories by using data measured down to GL-460m during construction as a part of the second phase of the MIU plan.
Yokota, Hideharu; Amano, Kenji; Maekawa, Keisuke; Kunimaru, Takanori; Naemura, Yumi*; Ijiri, Yuji*; Motoshima, Takayuki*; Suzuki, Shunichi*; Teshima, Kazufumi*
JAEA-Research 2013-002, 281 Pages, 2013/06
JAEA-Research-2013-002.pdf:13.03MB
To evaluate permeable heterogeneity in a fracture and scale effects which are problems to be solved based on the 
mass transportation data of fractures in hostrock, a number of tracer tests are simulated in a fictitious single plate fracture generated on computer in this study. And the transport parameters, e.g. longitudinal dispersion length, true velocity and dilution rate, are identified by fitting one- and two-dimensional models to the breakthrough curves obtained from the simulations in order to investigate the applicability of these models to the evaluation of tracer test. As a result, one-dimensional model yields larger longitudinal dispersion length than two-dimensional model in the both cases of homogeneous and heterogeneous hydraulic conductivity fields of the fictitious fracture. And, the longitudinal dispersion length identified from a tracer test is smaller and/or larger than the macroscopic longitudinal dispersion length identified from whole fracture. It is clarified that these are occurred by shorter or longer distance between boreholes compare to the correlation length of geostatistical heterogeneity of fictitious fracture.
Ijiri, Yuji*; Noda, Masaru*; Sasakura, Takeshi*; Nobuto, Jun*; Matsui, Hiroya; Mikake, Shinichiro; Hashizume, Shigeru
JAEA-Technology 2012-018, 288 Pages, 2012/07
JAEA-Technology-2012-018.pdf:19.13MB
The researches on engineering technology in the Mizunami Underground Research Laboratory plan consists of (1) research on engineering technology at a deep underground, and (2) research on engineering technology as a basis of geological disposal. The former research mainly aimed in this study are categorized in (a) development of design and construction planning technologies, (b) development of construction technology, (c) development of countermeasure technology, (d) development of technology for security. In this study, the researches on engineering technology are proceeded in these four categories by using data measured down to GL-300m during construction as a part of the second phase of the MIU plan.
Matsui, Hiroya; Ijiri, Yuji*; Kamemura, Katsumi*
Proceedings of ITA-AITES World Tunnel Congress 2012 (WTC 2012)/38th General Assembly (CD-ROM), 8 Pages, 2012/05
JAEA has been conducting research and development at two underground research laboratory projects, in crystalline and sedimentary rock at Mizunami, Gifu and Horonobe, Hokkaido respectively. In this report, individual risk assessment methods are shown based on existing studies on general underground construction projects and complementary data and experience obtained from the Mizunami URL project. The results suggest that risk assessments on geological disposal projects can utilize this methodology to assess risk in establishing the site description model for design and safety assessment of a repository, as was done in Phase I of the Mizunami URL. Thus the proposed methodology should have broad application and additional special investigations for risk management are not likely needed.
Kunimaru, Takanori; Ota, Kunio; Alexander, W. R.*; Yamamoto, Hajime*
JAEA-Research 2011-010, 52 Pages, 2011/06
JAEA-Research-2011-010.pdf:2.29MB
Work has been currently ongoing to establish an appropriate quality management system (QMS), which is applicable to all aspects of the site characterisation process, in the Horonobe Underground Research Laboratory project. A quality assurance (QA) audit of hydrochemical datasets for JAEA's deep boreholes HDB-1 to HDB-8 was carried out, along similar lines to that of the previous study for boreholes HDB-9 to HDB-11, by applying both the groundwater QA methodology employed in the recent site assessments in Sweden and a porewater QA regime proposed in this study. The results of the QA audit indicated that data were classified into low QA categories because mainly of a lack of relevant information, such as the records of groundwater sampling, which are necessary for more fully assessing the data quality. As such, a formalised field manual for hydrochemical sampling was developed. In addition, work to further improve the site characterisation QMS progressed.
Shimo, Michito*; Kumamoto, So*; Ito, Akira*; Karasaki, Kenji*; Sawada, Atsushi; Oda, Yoshihiro; Sato, Hisashi
JAEA-Research 2010-040, 57 Pages, 2010/11
JAEA-Research-2010-040.pdf:5.12MB
In safety analysis of geological disposal of the high-level nuclear waste, it is important to evaluate appropriately the mass transport characteristics of the bedrock as the natural barrier. Especially, it has been found that the porosity of the rock matrix is high and fractured zones are developing and therefore the mass transport characteristics will be the mixture of those for porous media and the fractured media. In this work, we conducted, (1) a study on the method to mine out the rock block sample of tens of-centimeter to maximum 1 m scale, (2) a study on a method of the tracer test using a rock block sample and a series of scoping analysis. We also examined the uncertainty associated the hydrogeological model using a method combining a forward and inverse analysis, based on the various type of data sets obtained at Horonobe site, such as the temperature distribution and hydraulic head and salinity distribution.
Sanada, Hiroyuki; Matsui, Hiroya; Ogawa, Toyokazu*; Kinomura, Koji*; Aoki, Tomoyuki*; Yamamoto, Takuya*
JAEA-Research 2009-050, 57 Pages, 2010/01
JAEA-Research-2009-050.pdf:8.14MB
It is important to understand EDZ in assessing performance of repository and designing of plug. It is known that it remains possible that the large-scale EDZ is generated due to strain localization from boring investigations and tunnel excavation analyses and rock properties changes with increase of depth. Excavation analysis of vertical shaft in sedimentary rock taken into account strain softening, depth variation of rock properties and the actual construction procedure had been done in order to understand EDZ of Horonobe URL. The large-scale EDZ due to strain localization was generated around the border between Koetoi formation and Wakkanai formation. From result obtained from excavation analysis, scale of EDZ obtained from excavation analysis is from 60 cm to 120 cm. And it was estimated that seismic velocity changed by 20 percent, elastic modulus changed by 30 percent and hydraulic conductivity changed by 0.1 m/s order.
Noda, Masaru*; Suyama, Yasuhiro*; Nobuto, Jun*; Ijiri, Yuji*; Mikake, Shinichiro; Matsui, Hiroya
JAEA-Technology 2009-009, 194 Pages, 2009/07
JAEA-Technology-2009-009.pdf:44.14MB
In construction phase in MIU, the study on engineering technology consist of following four subjects, which are Demonstration of design methodology of a greatly deepr underground structure, Demonstration of excavation and supplymentary methods of a greatly deepr underground structure, Demonstration of the countermeasure during excavation of a greatly deepr underground structure and Demonstration of the safe construction for a greatly deepr underground structure. In the study in FY2007, the design methodlogy in Phase 1 is verified until 200 m depth on excavation of ventilation shaft. A plan, countermeasure and concept for influence of differential water pressure, long-term maintenance and risk management in the view of geological disposal project were proposed.
