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Journal Articles

A Coupled modeling simulator for near-field processes in cement engineered barrier systems for radioactive waste disposal

Benbow, S. J.*; Kawama, Daisuke*; Takase, Hiroyasu*; Shimizu, Hiroyuki*; Oda, Chie; Hirano, Fumio; Takayama, Yusuke; Mihara, Morihiro; Honda, Akira

Crystals (Internet), 10(9), p.767_1 - 767_33, 2020/09

 Times Cited Count:1 Percentile:42.94(Crystallography)

Details are presented of the development of a coupled modeling simulator for assessing the evolution in the near-field of a geological repository for radioactive waste disposal where concrete is used as a backfill. The simulator uses OpenMI, a standard for exchanging data between simulation software programs at run-time, to form a coupled chemical-mechanical-hydrogeological model of the system. The approach combines a tunnel scale stress analysis finite element model, a discrete element model for accurately modeling the patterns of emerging cracks in the concrete, and a finite element and finite volume model of the chemical processes and alteration in the porous matrix and cracks in the concrete, to produce a fully coupled model of the system. Combining existing detailed simulation software in this way with OpenMI has the benefit of not relying on simplifications that might be necessary to combine all of the modeled processes in a single piece of software.

Journal Articles

Status of JENDL

Iwamoto, Osamu; Iwamoto, Nobuyuki; Shibata, Keiichi; Ichihara, Akira; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke

EPJ Web of Conferences, 239, p.09002_1 - 09002_6, 2020/09

 Times Cited Count:0

Journal Articles

Comparison of field data and numerical simulation of nitrate evolution in groundwater using the model of nitrate evolution

Abe, Toru*; Hirano, Fumio; Mihara, Morihiro; Honda, Akira

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(1), p.3 - 11, 2020/06

Degradation of TRU waste in a geological disposal facility may cause the formation of a nitrate plume. A Nitrate Evolution model due to mineral reactions, microbial activity, and metal corrosiON (NEON) has therefore been developed to evaluate the safety case for geological disposal of TRU waste. Small scale laboratory experiments can be reproduced satisfactorily, however, it is necessary to demonstrate the applicability of the NEON model on scales relevant to the geological disposal of TRU waste. In the current study, an industrial analogue of a nitrate plume from the pollution of groundwater from nitrate fertilizers used on Ikuchi Island, Japan was selected to test the applicability of the NEON model. Concentration profiles of nitrate ions in the groundwater were successfully reproduced over the hundreds of meters scale demonstrating the applicability of the NEON model in evaluating the chemical behavior of a nitrate plume derived from the geological disposal of TRU waste.

JAEA Reports

Survey of computational methods of cross sections for thermal neutron scattering by liquids

Ichihara, Akira

JAEA-Review 2019-046, 36 Pages, 2020/03

JAEA-Review-2019-046.pdf:1.55MB

Toward the revision of JENDL-4.0, we conducted a literature survey on how to compute the cross section of thermal neutrons scattered by a liquid. This report summarizes the computational methods for evaluating thermal neutron cross sections with molecular dynamics simulations. The cross section can be expressed with a function called as scattering law. For light and heavy water, the scattering law data instead of the cross sections have been provided in nuclear databases. In this report we review the formulations of the scattering laws. The scattering laws can be derived from both the intermediate scattering function and the space-time correlation function. Features of the derived scattering laws are briefly explained. It is shown that the scattering law data can be evaluated using a molecular dynamics simulation of the liquid that is the target of thermal neutrons.

Journal Articles

Study on characterization of colloidal silica grout for rock excavation under saline groundwater

Tsuji, Masakuni*; Nakashima, Hitoshi*; Saito, Akira*; Okihara, Mitsunobu*; Sato, Toshinori

45th Annual Waste Management Conference (WM 2019); Encouraging Young Men & Women to Achieve Their Goals in Radwaste Management, Vol.7, p.4749 - 4763, 2020/01

A rock excavation grouting technology has been recently studied as significant technology for reducing the ingress of water into the deep repository. However, it has not been studied for applying to the coastal region, where it is discussed to be a more suitable region for the geological disposal in Japan. The latest material called colloidal silica grout (CSG) is good for sealing narrow fractures but is known to be sensitive to the salinity of groundwater because of its gelling property with salt accelerator. Although the gelling of CSG can be controlled by adding an acidic pH adjuster, the methodology for delivering the appropriate grout is not well established for such conditions of saline groundwater. Therefore, this research project was established to enhance the existing rock grouting technology for deep repositories.

Journal Articles

Characterisation of colloidal silica for rock grouting under saline groundwater

Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Saito, Akira*; Aoyagi, Kazuhei; Sato, Toshinori

Dai-47-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (Internet), p.266 - 271, 2020/01

As engineering technique for geological disposal, a lot of advancement development of the grout technology has been performed. But the design, construction method in consideration of the properties of matter acquisition and mechanism of the hardening that assumed a seawater condition bottom is non-establishment. As we carried out the knowledge under saline water, the basic properties acquisition, the penetration properties acquisition, a study revue based on such situation.

Journal Articles

Hydration and degradation of High content Fly ash Silica fume Cement (HFSC)

Anraku, Sohtaro; Walker, C.*; Oda, Chie; Mihara, Morihiro; Honda, Akira

Proceedings of 15th International Congress on the Chemistry of Cement (ICCC 2019) (Internet), 11 Pages, 2019/09

Journal Articles

Formation of metal ion complexes in cementitious porewaters and leachates

Walker, C.*; Anraku, Sohtaro; Oda, Chie; Mihara, Morihiro; Honda, Akira

Proceedings of 15th International Congress on the Chemistry of Cement (ICCC 2019) (Internet), 11 Pages, 2019/09

Journal Articles

Radiochemical research for the advancement of $$^{99}$$Mo/$$^{rm 99m}$$Tc generator by (n,$$gamma$$) method

Fujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

KURNS Progress Report 2018, P. 155, 2019/08

no abstracts in English

Journal Articles

Transient ionization of the mesosphere during auroral breakup; Arase satellite and ground-based conjugate observations at Syowa Station

Kataoka, Ryuho*; Nishiyama, Takanori*; Tanaka, Yoshimasa*; Kadokura, Akira*; Uchida, Herbert Akihito*; Ebihara, Yusuke*; Ejiri, Mitsumu*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Sato, Kaoru*; et al.

Earth, Planets and Space (Internet), 71, p.9_1 - 9_10, 2019/01

 Times Cited Count:5 Percentile:32.16(Geosciences, Multidisciplinary)

Transient ionization of the mesosphere was detected at around 65 km altitude during the isolated auroral expansion occurred at 2221-2226 UT on June 30, 2017. A general-purpose Monte Carlo particle transport code PHITS suggested that significant ionization is possible in the middle atmosphere due to auroral X-rays from the auroral electrons of $$<$$10 keV.

Journal Articles

Status of development on LaB$$_6$$ filament arc-driven multi-cusp ion source for iBNCT

Shibata, Takanori*; Takagi, Akira*; Ikegami, Kiyoshi*; Sugimura, Takashi*; Nammo, Kesao*; Naito, Fujio*; Kobayashi, Hitoshi*; Kurihara, Toshikazu*; Honda, Yosuke*; Sato, Masaharu*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.385 - 387, 2018/10

Journal Articles

Theoretical calculation of neutron cross sections for $$^{90,91,92,94,96}$$Zr in the incident energy range between 200 keV and 20 MeV

Ichihara, Akira

Journal of Nuclear Science and Technology, 55(9), p.1087 - 1098, 2018/09

 Times Cited Count:1 Percentile:100(Nuclear Science & Technology)

Toward the revision of JENDL-4.0, neutron cross sections of $$^{90,91,92,94,96}$$Zr were calculated in the energy range between 200 keV and 20 MeV. The calculation was carried out by using nuclear reaction models such as the spherical optical model, the distorted wave Born approximation, preequilibrium models, and the multi-step statistical model. The obtained results were almost consistent with the experimental data. The cross sections were also estimated for the metastable states which had not been considered in the JENDL-4.0 evaluation. The experimental cross sections for the reactions $$^{90}$$Zr$$(n,2n)$$$$^{89m}$$Zr, $$^{91}$$Zr$$(n,x)$$$$^{90m}$$Y and $$^{91}$$Zr$$(n,nalpha)$$$$^{87m}$$Sr were well reproduced by the present calculation.

Journal Articles

Revising the 4${it f}$ symmetry in CeCu$$_{2}$$Ge$$_{2}$$; Soft X-ray absorption and hard X-ray photoemission spectroscopy

Aratani, Hidekazu*; Nakatani, Yasuhiro*; Fujiwara, Hidenori*; Kawada, Moeki*; Kanai, Yuina*; Yamagami, Kohei*; Fujioka, Shuhei*; Hamamoto, Satoru*; Kuga, Kentaro*; Kiss, Takayuki*; et al.

Physical Review B, 98(12), p.121113_1 - 121113_6, 2018/09

AA2018-0352.pdf:1.16MB

 Times Cited Count:3 Percentile:70.39(Materials Science, Multidisciplinary)

Journal Articles

Neutron irradiation effect of high-density MoO$$_{3}$$ pellets for Mo-99 production

Fujita, Yoshitaka; Nishikata, Kaori; Namekawa, Yoji*; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Zhang, J.*

KURRI Progress Report 2017, P. 126, 2018/08

no abstracts in English

Journal Articles

Evidence for momentum-dependent heavy fermionic electronic structures; Soft X-ray ARPES for the superconductor CeNi$$_{2}$$Ge$$_{2}$$ in the normal state

Nakatani, Yasuhiro*; Aratani, Hidekazu*; Fujiwara, Hidenori*; Mori, Takeo*; Tsuruta, Atsushi*; Tachibana, Shoichi*; Yamaguchi, Takashi*; Kiss, Takayuki*; Yamasaki, Atsushi*; Yasui, Akira*; et al.

Physical Review B, 97(11), p.115160_1 - 115160_7, 2018/03

AA2018-0003.pdf:1.65MB

 Times Cited Count:1 Percentile:90.33(Materials Science, Multidisciplinary)

JAEA Reports

Study on characterisation of colloidal silica grout under condition of sea water

Toguri, Satohito*; Okihara, Mitsunobu*; Tsuji, Masakuni*; Nakashima, Hitoshi*; Sugiyama, Hirokazu*; Saito, Akira*; Sato, Toshinori; Aoyagi, Kazuhei; Masunaga, Kosuke

JAEA-Research 2017-013, 131 Pages, 2018/02

JAEA-Research-2017-013.pdf:8.49MB

The discussions on scientifically promising site for the geological disposal has been made at the council of studying group on techniques for geological disposal of radioactive wastes, which is held by Resources and Energy Agency. From the aspect of ensuring safety during the transportation of disposal waste, the coastal area is discussed to be a more suitable area. This report shows the result of the first year of this project as following items; Study on the state-of-art technology and remain tasks; laboratory tests on characterization of colloidal silica grout under sea water; Study on the development of grouting technology (design and the evaluation method of influence on the rock mass).

Journal Articles

Evaluation of neutron resonance parameters for Zr isotopes

Ichihara, Akira

JAEA-Conf 2017-001, p.103 - 108, 2018/01

In the Nuclear Data Center of Japan Atomic Energy Agency (JAEA-NDC), we are engaged in the evaluation activity for the next version of the Japanese Evaluated Nuclear Data Library, JENDL-4.0. Zirconium is an important structural material in nuclear reactors, and zircaloys are being employed in fuel rods. Also, $$^{93}$$Zr is a long-lived fission product (LLFP) with a half-life of 1.61$$times$$10$$^{6}$$ years. At present we are investigating resonance parameters of Zr isotopes using experimental data published after the evaluation of JENDL-4.0. Through this work, a negative resonance of $$^{93}$$Zr in JENDL-4.0 was removed to reproduce the J-PARC/MLF/ANRRI experiment. The resonance parameters for other natural Zr isotopes will be altered by adopting the data obtained at CERN n-TOF experiments.

Journal Articles

Status of the JENDL project

Iwamoto, Osamu; Shibata, Keiichi; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Ichihara, Akira; Nakayama, Shinsuke

EPJ Web of Conferences, 146, p.02005_1 - 02005_6, 2017/09

 Times Cited Count:0 Percentile:100

Journal Articles

Pyroelectric power generation with ferroelectrics (1-x)PMN-xPT

Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.

Ferroelectrics, 512(1), p.92 - 99, 2017/08

 Times Cited Count:6 Percentile:54.89(Materials Science, Multidisciplinary)

Journal Articles

Experimental observation of temperature and magnetic-field evolution of the 4${it f}$ states in CeFe$$_{2}$$ revealed by soft X-ray magnetic circular dichroism

Saito, Yuji; Yasui, Akira*; Fuchimoto, Hiroto*; Nakatani, Yasuhiro*; Fujiwara, Hidenori*; Imada, Shin*; Narumi, Yasuo*; Kindo, Koichi*; Takahashi, Minoru*; Ebihara, Takao*; et al.

Physical Review B, 96(3), p.035151_1 - 035151_5, 2017/07

AA2017-0611.pdf:0.36MB

 Times Cited Count:1 Percentile:90.81(Materials Science, Multidisciplinary)

We revisit the delocalized character of the 4$$f$$ states of CeFe$$_2$$ in the ferromagnetically ordered phase by X-ray magnetic circular dichroism (XMCD) in X-ray absorption spectroscopy (XAS) with improved data quality using single crystals. Surprisingly, the Ce $$M_{4,5}$$ XMCD spectral shape changes significantly as a function of temperature and applied magnetic field, with no concomitant changes in the spectral shape of the Ce $$M_{4,5}$$ XAS as well as the Fe $$L_{2,3}$$ XAS and XMCD. This unusual behavior is characterized by the $$J=7/2$$ states in a 4$$f^1$$ configuration mixed into the $$J=5/2$$ ground state. Such extreme sensitivity of the Ce 4$$f$$ states to the external perturbations can be related to the magnetic instability toward an antiferromagnetic phase in CeFe$$_2$$. Our experimental data presented here provide valuable insights into the underlying physics in strongly-hybridized ferromagnetic Ce compounds.

311 (Records 1-20 displayed on this page)