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Journal Articles

Mode distribution analysis for superionic melt of CuI by coherent quasielastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Tahara, Shuta*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Maruyama, Kenji*; Yamauchi, Yasuhiro*; Kawamura, Seiko; Nakajima, Kenji

JPS Conference Proceedings (Internet), 33, p.011071_1 - 011071_6, 2021/03

CuI is a well-known superionic conductor in a high temperature solid phase where the mobile cations migrate between interstitial sites in the f.c.c. sublattice formed by iodine ions. Even in the molten state, it shows several features suggesting collective or cooperative ionic motion. MD results show that Cu diffuses much faster than I. The Cu-Cu partial structure factor have a FSDP which indicates a medium-range ordering of Cu ions. Moreover the Cu-Cu partial pair distribution deeply penetrates into the nearest neighboring Cu-I shell. To reveal origin such anomalous behaviors of molten CuI, we performed quaiselastic neutron scattering (QENS) by the disk-chopper spectrometer AMATERAS at MLF, J-PARC. To interpret the total dynamic structure factor obtained from coherent QENS, the mode distribution analysis was applied. It is found that the motion of iodine is a kind of fluctuating within an almost local area while Cu ions diffuse much faster than iodine ions.

JAEA Reports

Development of the Unified Cross-section Set ADJ2017

Yokoyama, Kenji; Sugino, Kazuteru; Ishikawa, Makoto; Maruyama, Shuhei; Nagaya, Yasunobu; Numata, Kazuyuki*; Jin, Tomoyuki*

JAEA-Research 2018-011, 556 Pages, 2019/03


We have developed a new unified cross-section set ADJ2017, which is an improved version of the unified cross-section set ADJ2010 for fast reactors. The unified cross-section set is used for reflecting information of C/E values (analysis / experiment values) obtained by integral experiment analyses; the values are stored in the standard database for FBR core design via the cross-section adjustment methodology, which integrates with the information such as uncertainty (covariance) of nuclear data, uncertainty of integral experiment / analysis, sensitivity of integral experiment with respect to nuclear data. The ADJ2017 is based on Japan's latest nuclear data library JENDL-4.0 as in the previous version of ADJ2010, and it incorporates more information on integral experimental data sets related to minor actinides (MAs) and degraded plutonium (Pu). In the creation of ADJ2010, a total of 643 integral experimental data sets were analyzed and evaluated, and 488 of the integral experimental data sets were finally selected to be used for the cross-section adjustment. In contrast, we have evaluated a total of 719 data sets, and eventually adopted 620 integral experimental data sets to create ADJ2017. ADJ2017 shows almost the same performance as ADJ2010 for the main neutronic characteristics of conventional sodium-cooled MOX-fuel fast reactors. In addition, for the neutronic characteristics related to MA and degraded Pu, ADJ2017 improves the C/E values of the integral experimental data sets, and reduces the uncertainty induced by the nuclear data. ADJ2017 is expected to be widely used in the analysis and design research of fast reactors. Moreover, it is expected that the integral experimental data sets used for ADJ2017 can be utilized as a standard database of FBR core design.

Journal Articles

Anomaly of structural relaxation in complex liquid metal of bismuth; Dynamic correlation function of coherent quasi-elastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

Physica B; Condensed Matter, 551, p.291 - 296, 2018/12

 Times Cited Count:8 Percentile:49.07(Physics, Condensed Matter)

There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

Neutron devices such as neutron detectors, optical devices including supermirror devices and $$^{3}$$He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

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

Global continuous optimization with error bound and fast convergence

Kawaguchi, Kenji*; Maruyama, Yu; Zheng, X.

Journal of Artificial Intelligence Research, 56, p.153 - 195, 2016/06

 Times Cited Count:10 Percentile:58.13(Computer Science, Artificial Intelligence)

Journal Articles

Development of a fast reactor for minor actinides transmutation; Improvement of prediction accuracy for MA-related integral parameters based on cross-section adjustment technique

Yokoyama, Kenji; Maruyama, Shuhei; Numata, Kazuyuki; Ishikawa, Makoto; Takeda, Toshikazu*

Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.1906 - 1915, 2016/05

Journal Articles

Precise determination of $$^{12}_{Lambda}$$C level structure by $$gamma$$-ray spectroscopy

Hosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08

 Times Cited Count:13 Percentile:70.14(Physics, Multidisciplinary)

Level structure of the $$^{12}_{Lambda}$$C hypernucleus was precisely determined by means of $$gamma$$-ray spectroscopy. We identified four $$gamma$$-ray transitions via the $$^{12}$$C$$(pi^{+},K^{+}gamma)$$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $$(2^{-}, 1^{-}_{1})$$ was measured to be $$161.5pm0.3$$(stat)$$pm0.3$$ (syst)keV from the direct $$M1$$ transition. Excitation energies of the $$1^{-}_{2}$$ and $$1^{-}_{3}$$ states were measured to be $$2832pm3pm4$$, keV and $$6050pm8pm7$$, keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $$Lambda$$ hypernuclei.

Journal Articles

On-site background measurements for the J-PARC E56 experiment; A Search for the sterile neutrino at J-PARC MLF

Ajimura, Shuhei*; Bezerra, T. J. C.*; Chauveau, E.*; Enomoto, T.*; Furuta, Hisataka*; Harada, Masahide; Hasegawa, Shoichi; Hiraiwa, T.*; Igarashi, Yoichi*; Iwai, Eito*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(6), p.063C01_1 - 063C01_19, 2015/06

 Times Cited Count:3 Percentile:32.69(Physics, Multidisciplinary)

The J-PARC E56 experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Science Experimental Facility (MLF). In order to examine the feasibility of the experiment, we measured the background rates of different detector candidate sites, which are located at the third floor of the MLF, using a detector consisting of plastic scintillators with a fiducial mass of 500 kg. The gammas and neutrons induced by the beam as well as the backgrounds from the cosmic rays were measured, and the results are described in this article.

Journal Articles

Application of Bayesian nonparametric models to the uncertainty and sensitivity analysis of source term in a BWR severe accident

Zheng, X.; Ito, Hiroto; Kawaguchi, Kenji; Tamaki, Hitoshi; Maruyama, Yu

Reliability Engineering & System Safety, 138, p.253 - 262, 2015/06

 Times Cited Count:7 Percentile:40.76(Engineering, Industrial)

Journal Articles

Analysis for iodine release from Unit 3 of Fukushima Dai-ichi Nuclear Power Plant with consideration of water phase iodine chemistry

Ishikawa, Jun; Kawaguchi, Kenji; Maruyama, Yu

Journal of Nuclear Science and Technology, 52(3), p.308 - 314, 2015/03

 Times Cited Count:8 Percentile:54.79(Nuclear Science & Technology)

no abstracts in English

Journal Articles

An Adaptive time-stepping scheme with local convergence verification using support vector machines

Kawaguchi, Kenji; Ishikawa, Jun; Maruyama, Yu

International Journal of Engineering and Technology, 6(2), p.104 - 108, 2014/04

JAEA Reports

Study to improve recriticality evaluation methodology after severe accident (Joint research)

Kugo, Teruhiko; Ishikawa, Makoto; Nagaya, Yasunobu; Yokoyama, Kenji; Fukaya, Yuji; Maruyama, Hiromi*; Ishii, Yoshihiko*; Fujimura, Koji*; Kondo, Takao*; Minato, Hirokazu*; et al.

JAEA-Research 2013-046, 53 Pages, 2014/03


The present report summarizes the results of a 2-year cooperative study between JAEA and Hitachi-GE in order to contribute to the settlement of the Fukushima-Daiichi Nuclear Power Plants which suffered from the severe accident on March 2011. In the present study, the possible scenarios to reach the recriticality events in Fukushima-Daiichi were investigated first. Then, the analytical methodology to evaluate the time-dependent recriticality events has been developed by modelling the reactivity insertion rate and the possible feedback according to the recriticality scenarios identified in the first step. The methodology developed here has been equipped as a transient simulation tool, PORCAS, which is operated on a multi-purpose platform for reactor analysis, MARBLE. Finally, the radiation exposure rates by the postulated recriticality events in Fukushima-Daiichi were approximately evaluated to estimate the impact to the public environment.

Journal Articles

AMATERAS; A Cold-neutron disk chopper spectrometer

Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Nakamura, Mitsutaka; Kajimoto, Ryoichi; Inamura, Yasuhiro; Takahashi, Nobuaki; Aizawa, Kazuya; Suzuya, Kentaro; Shibata, Kaoru; et al.

Journal of the Physical Society of Japan, 80(Suppl.B), p.SB028_1 - SB028_6, 2011/05

 Times Cited Count:90 Percentile:94.38(Physics, Multidisciplinary)

AMATERAS is a cold-neutron disk-chopper spectrometer in MLF, J-PARC. The construction of main part of the spectrometer has been completed in spring of 2009. Soon after that, we have started the commissioning work on AMATERAS. The performance of AMATERAS has been examined by test experiments in the course of commissioning. In parallel to these works, we have started the user program on AMATERAS from December 2009 and we are getting scientific results from our spectrometer. In this presentation, we will report the current status of AMATERAS including the results of performance tests and some of examples of scientific outputs.

Journal Articles

The Fermi chopper spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Nakajima, Kenji; Kawamura, Seiko; Yokoo, Tetsuya*; Nakatani, Takeshi; Maruyama, Ryuji; Soyama, Kazuhiko; et al.

Journal of the Physical Society of Japan, 80(Suppl.B), p.SB025_1 - SB025_6, 2011/01

 Times Cited Count:71 Percentile:92.29(Physics, Multidisciplinary)

Journal Articles

Formation of nuclear "Pasta" in supernovae

Watanabe, Gentaro*; Sonoda, Hidetaka*; Maruyama, Toshiki; Sato, Katsuhiko*; Yasuoka, Kenji*; Ebisuzaki, Toshikazu*

Physical Review Letters, 103(12), p.121101_1 - 121101_4, 2009/09

 Times Cited Count:66 Percentile:90.96(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Simulation of transitions between "Pasta" phases in dense matter

Watanabe, Gentaro*; Maruyama, Toshiki; Sato, Katsuhiko*; Yasuoka, Kenji*; Ebisuzaki, Toshikazu*

Physical Review Letters, 94(3), p.031101_1 - 031101_4, 2005/01

 Times Cited Count:86 Percentile:91.85(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Development of a spin flipper for an application of a neutron magnetic device

Oku, Takayuki*; Sakai, Kenji*; Adachi, Tomohiro*; Ikeda, Kazuaki*; Shimizu, Hirohiko*; Maruyama, Ryuji*; Hino, Masahiro*; Tasaki, Seiji*; Kiyanagi, Yoshiaki*; Kamiyama, Takashi*; et al.

Physica B; Condensed Matter, 335(1-4), p.226 - 229, 2003/07

 Times Cited Count:7 Percentile:40.51(Physics, Condensed Matter)

no abstracts in English

Journal Articles

MCD study on materials without magnetic order

Miyahara, Tsuneaki*; Ishii, Hiroyoshi*; Takayama, Yasuhiro*; Hirose, Masaaki*; Maruyama, Kenichi*; Obu, Kenji*; Shinoda, Motoki*; Muro, Takayuki*; Saito, Yuji; Matsuda, Tatsuma*; et al.

Journal of the Physical Society of Japan, 70(10), p.2977 - 2981, 2001/10

 Times Cited Count:5 Percentile:38.89(Physics, Multidisciplinary)

no abstracts in English

Oral presentation

Development of advanced reprocessing system using high selective and controllable precipitants, 2; Evaluation of radiation and heat resistance of low coordinate and hydrophobic pyrrolidone derivatives

Maruyama, Koichi*; Nogami, Masanobu*; Ikeda, Yasuhisa*; Nishimura, Kenji*; Morita, Yasuji

no journal, , 

Radiation and heat resistance of low coordinate and hydrophobic pyrrolidone derivatives, NProP and NBP, which are selective precipitants for U(VI), was examined by $$gamma$$-irradiation and heating of the 3M nitric and solutions of the precipitants. Test results of radiation resistance of NProP and NBP showed that the ability to make precipitate of U(VI) was kept until 0.5 MGy of irradiation. After the heating of the 3M nitric and solutions of NProP and NBP at 50 $$^{circ}$$C, the molecular structures of NBP and NProP were changed within 4 days and 10days, respectively. It was found that the change of the structure does not weaken but reinforce the ability to make precipitate of U(VI), which would due to the increase of the hydrophobicity.

42 (Records 1-20 displayed on this page)