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Journal Articles

Variation in fault hydraulic connectivity with depth in mudstone; An Analysis of poroelastic hydraulic response to excavation in the Horonobe URL

Ozaki, Yusuke; Ishii, Eiichi; Sugawara, Kentaro*

Geomechanics for Energy and the Environment, 31, p.100311_1 - 100311_13, 2022/09

 Times Cited Count:3 Percentile:52.76(Energy & Fuels)

This study analyzed the long-term hydraulic pressure data during the excavation of Horonobe URL to estimate the variation of effective-hydraulic-conductivity. We performed the numerical simulation with the poroelastic effect for the estimation because the observed hydraulic pressure is highly affected by the Mandel-Cryer effect. The evaluation of the observed data based on our simulation results showed that the effective-hydraulic-conductivity gradually decreases from 400 m to 500 m in depth and is as low as the intact rock at depths greater than 500 m. Not only the analysis based on our simulation results but also the analysis based on analytical solution indicate the domain with different hydraulic properties in the Wakkanai Formation. These results suggest that the fracture-hydraulic-connectivity changes not abruptly but gradually over several tens of meters around the predicted boundary.

Journal Articles

Event tree analysis for material relocation on core catcher in a sodium-cooled fast reactor

Yamano, Hidemasa; Kubo, Shigenobu; Kan, Taro*; Shibata, Akihiro*; Hourcade, E.*; Dirat, J. F.*

Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 10 Pages, 2022/08

In this paper, the approach to event tree development and the scope of the event tree analysis were described with key points on core catcher loading. For the analytical conditions, two core catcher loading conditions were given as bounding and conservative cases. For important heading of the event tree, key important phenomena were included: strong back design, fuel-coolant interaction and quench in the sodium plenum design, jet attack, criticality and coolability on the core catcher. In this paper, preliminary trial quantification was attempted using a probability ranking table which is based on engineering judgement. This event tree analysis has identified the dominant sequence, and clarified the effect of the core catcher loading and effectiveness of design measures. This study suggests that the criticality measure is very important for the core catcher study.

Journal Articles

High-spin states in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.

Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03

 Times Cited Count:4 Percentile:58.42(Physics, Nuclear)

Journal Articles

Poroelastic hydraulic-response of fractured mudstone to excavation in the Horonobe URL; As an indicator of fracture hydraulic-disconnectivity

Ozaki, Yusuke; Ishii, Eiichi; Sugawara, Kentaro*

Extended abstract of International Conference on Coupled Processes in Fractured Geological Media; Observation, Modeling, and Application (CouFrac 2020) (Internet), 4 Pages, 2020/11

We perform the numerical simulation of the response of hydraulic head observed in HDB-6 during the excavation of the Horonobe URL to verify the existence of low effective permeable domain in the subsurface. The low permeable domain as an intact rock due to the low hydraulic fracture connectivity is estimated to exist in the deep domain while the permeability of the shallow domain is relatively high due to the hydraulic fracture connectivity there. Our simulation shows that the observed hydraulic head is affected by the Mandel-Cryer effect due to the hydrogeological structure and the effect for the duration of over years requires the low permeability as an intact rock in the deep domain. These results verify the existence of the low effective permeable domain in the deep subsurface estimated by the previous study.

Journal Articles

Development of cryogenic tensile testing apparatus for lattice strain measurement using synchrotron radiation for REBCO composite conductors

Sugano, Michinaka*; Machiya, Shutaro*; Shobu, Takahisa; Shiro, Ayumi*; Kajiwara, Kentaro*; Nakamoto, Tatsushi*

Superconductor Science and Technology, 33(8), p.085003_1 - 085003_10, 2020/08

 Times Cited Count:4 Percentile:27.19(Physics, Applied)

Journal Articles

Biomolecule-assisted synthesis of hierarchical multilayered boehmite and alumina nanosheets for enhanced molybdenum adsorption

Saptiama, I.*; Kaneti, Y. V.*; Yuliarto, B.*; Kumada, Hiroaki*; Tsuchiya, Kunihiko; Fujita, Yoshitaka; Malgras, V.*; Fukumitsu, Nobuyoshi*; Sakae, Takeji*; Hatano, Kentaro*; et al.

Chemistry; A European Journal, 25(18), p.4843 - 4855, 2019/03

 Times Cited Count:14 Percentile:55.95(Chemistry, Multidisciplinary)

The effective utilization of various biomolecules for creating a series of mesoporous boehmite ($$gamma$$-AlOOH) and gamma-alumina ($$gamma$$-Al$$_{2}$$O$$_{3}$$) nanosheets with unique hierarchical multilayered structures is demonstrated. The nature and concentration of the biomolecules strongly influence the degree of the crystallinity, the morphology, and the textural properties of the resulting $$gamma$$-AlOOH and $$gamma$$-Al$$_{2}$$O$$_{3}$$ nanosheets, allowing for easy tuning. The hierarchical $$gamma$$-AlOOH and $$gamma$$-Al$$_{2}$$O$$_{3}$$ multilayered nanosheets synthesized by using biomolecules exhibit enhanced crystallinity, improved particle separation, and well-defined multilayered structures compared to those obtained without biomolecules. More impressively, these $$gamma$$-AlOOH and $$gamma$$-Al$$_{2}$$O$$_{3}$$ nanosheets possess high surface areas up to 425 and 371 m$$^{2}$$/g, respectively, due to their mesoporous nature and hierarchical multilayered structure. When employed for molybdenum adsorption toward medical radioisotope production, the hierarchical $$gamma$$-Al$$_{2}$$O$$_{3}$$ multilayered nanosheets exhibit Mo adsorption capacities of 33.1$$sim$$40.8mg-Mo/g.

Journal Articles

Estimation of in situ stress based on the measurement of convergence during gallery excavation

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

Journal Articles

Development of in situ stress estimation method based on the measured convergence and geological observations

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 $$times$$ 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.

Journal Articles

Electron heat diffusivity in radially-bounded ergodic region of toroidal plasma

Kanno, Ryutaro*; Nunami, Masanori*; Satake, Shinsuke*; Matsuoka, Seikichi; Takamaru, Hisanori*

Nuclear Fusion, 58(1), p.016033_1 - 016033_7, 2018/01

 Times Cited Count:0 Percentile:0.01(Physics, Fluids & Plasmas)

The electron heat transport in a torus plasma which involves a radially-bounded ergodic region, where flux surfaces are partially destroyed by perturbative magnetic fields, is studied. In this paper, we have demonstrated that the radial heat conduction by the particles' parallel motion is reduced by trapped particles.

Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:3 Percentile:86.59

Journal Articles

Development of a back analysis method for the estimation of in situ stress based on the measured convergence in the Horonobe Underground Research Laboratory

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.

Journal Articles

Model verification and validation procedure for a neutronics design methodology of next generation fast reactors

Ohgama, Kazuya; Ikeda, Kazumi*; Ishikawa, Makoto; Kan, Taro*; Maruyama, Shuhei; Yokoyama, Kenji; Sugino, Kazuteru; Nagaya, Yasunobu; Oki, Shigeo

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 10 Pages, 2017/04

Journal Articles

Core performance requirements and design conditions for next-generation sodium-cooled fast reactor in Japan

Oki, Shigeo; Maruyama, Shuhei; Chikazawa, Yoshitaka; Ohtaki, Akira; Kubo, Shigenobu; Hibi, Koki*; Kan, Taro*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 9 Pages, 2017/04

Journal Articles

Core design of the next-generation sodium-cooled fast reactor in Japan

Kan, Taro*; Ogura, Masashi*; Hibi, Koki*; Oki, Shigeo; Maeda, Seiichiro; Maruyama, Shuhei; Ohgama, Kazuya

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 10 Pages, 2017/04

Journal Articles

Benchmark of the local drift-kinetic models for neoclassical transport simulation in helical plasmas

Huang, B.*; Satake, Shinsuke*; Kanno, Ryutaro*; Sugama, Hideo*; Matsuoka, Seikichi

Physics of Plasmas, 24(2), p.022503_1 - 022503_19, 2017/02

 Times Cited Count:11 Percentile:54.45(Physics, Fluids & Plasmas)

The drift kinetic equation describes the collisional (neoclassical) transport in plasmas. Recently, a novel radially-local approximation of the drift kinetic equation, which is called the zero orbit width (ZOW) model, is proposed. In this work, as a numerical verification of the neoclassical transport based on the ZOW model, we perform a series of benchmarks of the neoclassical transport and the parallel flow in three helical magnetic configurations using various types of radially-local approximation models including the ZOW model. We found that the neoclassical transport of the ZOW model can reproduce that based on the other models when the radial electric field and thus the $$E times B$$ drift is large. Also, it is demonstrated that an unphysical large radial transport, which arises in the neoclassical transport of the other models when the $$E times B$$ drift is small and compared to the magnetic drift, can be mitigated in the ZOW model.

Journal Articles

Estimation of rock mass stress state based on the convergence measurement result during tunnel excavation

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.

Journal Articles

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 Times Cited Count:7 Percentile:91.29

Journal Articles

Estimation of rock mass stress state based on convergence measurement during gallery excavation

Aoyagi, Kazuhei; Nago, Makito*; Kamemura, Katsumi*; Sugawara, Kentaro*

Proceedings of 9th Asian Rock Mechanics Symposium (ARMS-9) (USB Flash Drive), 10 Pages, 2016/10

Journal Articles

Development of a drift-kinetic simulation code for estimating collisional transport affected by RMPs and radial electric field

Kanno, Ryutaro*; Nunami, Masanori*; Satake, Shinsuke*; Matsuoka, Seikichi; Takamaru, Hisanori*

Contributions to Plasma Physics, 56(6-8), p.592 - 597, 2016/08

 Times Cited Count:2 Percentile:11.69(Physics, Fluids & Plasmas)

A drift-kinetic $$delta f$$ simulation code is developed for estimating collisional transport in quasi-steady state of toroidal plasma affected by resonant magnetic perturbations and radial electric field. In this paper, validity of the code is confirmed through several test calculations. It is found that radial electron flux is reduced by positive radial-electric field, although radial diffusion of electron is strongly affected by chaotic field-lines under an assumption of zero electric field.

Journal Articles

Radially local approximation of the drift kinetic equation

Sugama, Hideo*; Matsuoka, Seikichi; Satake, Shinsuke*; Kanno, Ryutaro*

Physics of Plasmas, 23(4), p.042502_1 - 042502_11, 2016/04

 Times Cited Count:5 Percentile:27.5(Physics, Fluids & Plasmas)

A novel radially local approximation of the drift kinetic equation is presented. The new drift kinetic equation that includes both $$rm E times B$$ and tangential magnetic drift terms is written in the conservative form and it has favorable properties for numerical simulation that any additional terms for particle and energy sources are unnecessary for obtaining stationary solutions under the radially local approximation. These solutions satisfy the intrinsic ambipolarity condition for neoclassical particle fluxes in the presence of quasisymmetry of the magnetic field strength. Also, another radially local drift kinetic equation is presented, from which the positive definiteness of entropy production due to neoclassical transport and Onsager symmetry of neoclassical transport coefficients are derived while it sacrifices the ambipolarity condition for neoclassical particle fluxes in axisymmetric and quasi-symmetric systems.

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