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Journal Articles

Superior TRIP effect in a duplex stainless steel and its mechanism studied by ${it in situ}$ neutron diffraction experiments

Tsuchida, Noriyuki*; Fujita, Akinori*; Hirakawa, Naoki*; Hamada, Junichi*; Ishimaru, Eiichiro*; Gong, W.; Kawasaki, Takuro; Harjo, S.

Materials Characterization, 236, p.116436_1 - 116436_13, 2026/06

 Times Cited Count:1 Percentile:80.99(Materials Science, Multidisciplinary)

JAEA Reports

Re-evaluation of nuclear criticality characteristics for infinite and finite heterogeneous lattice systems composed of uranium-zirconium hydride fuel rods used in the TRIGA annular core pulse reactor NSRR

Yanagisawa, Hiroshi; Motome, Yuiko

JAEA-Research 2025-010, 197 Pages, 2025/11

JAEA-Research-2025-010.pdf:3.5MB

For understandings of nuclear criticality risks of TRIGA fuel rods and review of safety measures for handling them, nuclear criticality characteristics for infinite and finite heterogeneous lattice systems composed of the NSRR fuel rods were re-evaluated with the use of a detailed computational model for the fuel rod. The MVP version 3 code was used with the JENDL libraries including the latest version, JENDL-5, for the re-evaluation. As the criticality characteristics, variations of neutron multiplication factors of the infinite and water-reflected finite systems were examined in detail with parameters of the lattice pitch and density of moderator water. From the results of the re-evaluated criticality characteristics, the minimum critical number of fuel rods for the water-reflected hexagonal shaped lattice system was obtained to be 46.8 $$pm$$ 0.2 using the JENDL-5 library. Moreover, the attainability of criticality without the water as moderator and reflector was examined because the zirconium hydride moderator and graphite reflector are equipped with the TRIGA fuel rod. It was found that the criticality is possible to be attained by 115.7 $$pm$$ 0.6 of the number of fuel rods, which is the smaller number of fuel rods than loaded in the NSRR standard core, even though no water exists.

Journal Articles

Microscopic insights into the mechanical behavior of a Ni-Co-based superalloy through ${it in-situ}$ neutron diffraction

Liu, Y.*; Yan, Z.*; Gao, Y.*; Li, Y.*; Gan, B.*; Harjo, S.; Gong, W.; Kawasaki, Takuro; Li, S.*; Wang, Y.-D.*

Microstructures (Internet), 5(4), p.2025096_1 - 2025096_15, 2025/10

Journal Articles

Large magnetic Bragg peak enhancement by ultrasound injection on FeTiO$$_3$$

Shamoto, Shinichi; Shin, K.*; Akatsu, Mitsuhiro*; Imai, Masaki; Ueta, Daichi*; Yokoo, Tetsuya*; Nemoto, Yuichi*; Hassan, A. M. A.*; Chang, L.-J.*; Ieda, Junichi; et al.

Applied Physics Letters, 127(13), p.132403_1 - 132403_5, 2025/09

 Times Cited Count:0 Percentile:0.00(Physics, Applied)

Journal Articles

Experiments on central reaction rate ratios and fission distributions in the FCA-XXII-1 assembly simulating highly enriched MOX-fueled tight lattice LWR cores

Fukushima, Masahiro; Ando, Masaki; Nagaya, Yasunobu

Nuclear Science and Engineering, 199(6), p.1029 - 1043, 2025/06

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

Experiments on criticality and reactivity worths in the FCA-XXII-1 assembly simulating highly enriched MOX fueled tight lattice LWR cores

Fukushima, Masahiro; Ando, Masaki; Nagaya, Yasunobu

Nuclear Science and Engineering, 199(1), p.18 - 41, 2025/01

 Times Cited Count:2 Percentile:36.47(Nuclear Science & Technology)

A series of integral experiments were conducted at FCA of JAEA, simulating LWR cores with a tight lattice cell of highly enriched MOX fuel containing more than 15% fissile plutonium. The three experimental configurations were constructed using foamed polystyrene with different void fractions to clarify the prediction accuracy of neutronic calculation codes and nuclear data among various neutron spectra. The nuclear characteristics measured in the experiments were criticality, moderator void reactivity worths, and sample reactivity worths. The preliminary analyses on experiments were conducted using a deterministic calculation code conventionally used for fast reactors with JENDL-4.0. Most reactivity worth calculations correlated well with the experimental values. Specifically for the softer neutron spectra configurations, the treatment of ultrafine energy groups obviously improved the prediction accuracy of the deterministic calculations. Furthermore, reference calculations were performed with MVP3 code by modeling the experimental setup in detail, confirming the validity of the deterministic calculations.

Journal Articles

Spin caloritronics in metallic superlattices

Seki, Takeshi*; Uchida, Kenichi*; Takanashi, Koki

Journal of Physics; Condensed Matter, 36(33), p.333001_1 - 333001_11, 2024/05

 Times Cited Count:3 Percentile:4.62(Physics, Condensed Matter)

Journal Articles

Ionic radii in fluorites

Vauchy, R.; Hirooka, Shun; Murakami, Tatsutoshi

Materialia, 32, p.101934_1 - 101934_12, 2023/12

Journal Articles

Ionic radii in halites

Vauchy, R.; Hirooka, Shun; Murakami, Tatsutoshi

Materialia, 32, p.101943_1 - 101943_8, 2023/12

Journal Articles

X-ray free electron laser observation of ultrafast lattice behaviour under femtosecond laser-driven shock compression in iron

Sano, Tomokazu*; Matsuda, Tomoki*; Hirose, Akio*; Terai, Tomoyuki*; Kakeshita, Tomoyuki*; Inubushi, Yuichi*; Sato, Takahiro*; Yabashi, Makina*; Shobu, Takahisa; 22 of others*

Scientific Reports (Internet), 13, p.13796_1 - 13796_10, 2023/08

 Times Cited Count:5 Percentile:28.39(Multidisciplinary Sciences)

Journal Articles

The Investigations of the $$P$$-wave $$B_s$$ states combining quark model and lattice QCD in the coupled channel framework

Yang, Z.*; Wang, G.-J.*; Wu, J.-J.*; Oka, Makoto; Zhu, S.-L.*

Journal of High Energy Physics (Internet), 2023(1), p.058_1 - 058_19, 2023/01

 Times Cited Count:12 Percentile:69.53(Physics, Particles & Fields)

Combining the quark model, the quark-pair-creation mechanism and $$B^{(*)}bar K$$ interaction, we have investigated the near-threshold $$P$$-wave $$B_s$$ states in the framework of the Hamiltonian effective field theory. With the heavy quark flavor symmetry, all the parameters are determined in the $$D_s$$ sector by fitting the lattice data. The masses of the bottom-strange partners of the $$D^{*}_{s0}(2317)$$ and $$D^{*}_{s1}(2460)$$ are predicted, which are well consistent with the lattice QCD simulation. The two $$P$$-wave $$B_s$$ states are the mixtures of the bare $$bar b s$$ core and $$B^{(*)}bar K$$ component. Moreover, we find a crossing point between the energy levels with and without the interaction Hamiltonian in the finite volume spectrum in the $$0^+$$ case, which corresponds to a CDD (Castillejo-Dalitz-Dyson) zero in the $$T$$-matrix of the $$Bbar K$$ scattering. This CDD zero will help deepen the insights of the near-threshold states and can be examined by future lattice calculation.

Journal Articles

Experimental evidence for the significance of optical phonons in thermal transport of tin monosulfide

Wu, P.*; Murai, Naoki; Li, T.*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Kofu, Maiko; Nakajima, Kenji; Xia, K.*; Peng, K.*; Zhang, Y.*; et al.

New Journal of Physics (Internet), 25(1), p.013032_1 - 013032_11, 2023/01

 Times Cited Count:3 Percentile:35.66(Physics, Multidisciplinary)

Journal Articles

Free-surface flow simulations with floating objects using lattice Boltzmann method

Watanabe, Seiya*; Kawahara, Jun*; Aoki, Takayuki*; Sugihara, Kenta; Takase, Shinsuke*; Moriguchi, Shuji*; Hashimoto, Hirotada*

Engineering Applications of Computational Fluid Mechanics, 17(1), p.2211143_1 - 2211143_23, 2023/00

 Times Cited Count:21 Percentile:86.36(Engineering, Multidisciplinary)

In tsunami inundations or slope disasters of heavy rain, a lot of floating debris or driftwood logs are included in the flows. The damage to structures from solid body impacts is more severe than the damage from the water pressure. In order to study free-surface flows that include floating debris, developing a high-accurate simulation code of free-surface flows with high performance for large-scale computations is desired. We propose the single-phase free-surface flow model based on the cumulant lattice Boltzmann method coupled with a particle-based rigid body simulation. The discrete element method calculates the contact interaction between solids. An octree-based AMR (Adaptive Mesh Refinement) method is introduced to improve computational accuracy and time-to-solution. High-resolution grids are assigned near the free surfaces and solid boundaries. We conducted two kinds of tsunami flow experiments in the 15 and 70 m water tanks at Hachinohe Institute of Technology and Kobe University to validate the accuracy of the proposed model. The simulation results have shown good agreement with the experiments for the drifting speed, the number of trapped wood pieces, and the stacked angles.

Journal Articles

Antiferromagnetism and mixed valency in the new Kondo lattice compound Ce$$_{3}$$Rh$$_{4}$$Sn$$_{7}$$

Opletal, P.; Duverger-N$'e$dellec, E.*; Miliyanchuk, K.*; Malick, S.*; Hossain, Z.*; Custers, J.*

Journal of Alloys and Compounds, 927, p.166941_1 - 166941_7, 2022/12

 Times Cited Count:6 Percentile:30.08(Chemistry, Physical)

Journal Articles

Quantum critical spin-liquid-like behavior in the $$S$$ = $$frac{1}{2}$$ quasikagome-lattice compound CeRh$$_{1-x}$$Pd$$_x$$Sn investigated using muon spin relaxation and neutron scattering

Tripathi, R.*; Adroja, D. T.*; Ritter, C.*; Sharma, S.*; Yang, C.*; Hillier, A. D.*; Koza, M. M.*; Demmel, F.*; Sundaresan, A.*; Langridge, S.*; et al.

Physical Review B, 106(6), p.064436_1 - 064436_17, 2022/08

 Times Cited Count:13 Percentile:62.69(Materials Science, Multidisciplinary)

Journal Articles

Novel coupled channel framework connecting the quark model and lattice QCD for the near-threshold $$D_s$$ states

Yang, Z.*; Wang, G.-J.*; Wu, J.-J.*; Oka, Makoto; Zhu, S.-L.*

Physical Review Letters, 128(11), p.112001_1 - 112001_6, 2022/03

 Times Cited Count:68 Percentile:97.17(Physics, Multidisciplinary)

A novel framework is proposed to extract near-threshold resonant states from finite-volume energy levels of lattice QCD and is applied to elucidate structures of the positive parity $$D_s$$. The quark model, the quark-pair-creation mechanism and $$D^{(*)}K$$ interaction are incorporated into the Hamiltonian effective field theory. The bare $$1^+$$ $$cbar s$$ states are almost purely given by the states with heavy-quark spin bases. The physical $$D^*_{s0}(2317)$$ and $$D^*_{s1}(2460)$$ are the mixtures of bare $$cbar s$$ core and $$D^{(*)}K$$ component, while the $$D^*_{s1}(2536)$$ and $$D^*_{s2}(2573)$$ are almost dominated by bare $$cbar{s}$$. Furthermore, our model well reproduce the clear level crossing of the $$D^*_{s1}(2536)$$ with the scattering state at a finite volume.

Journal Articles

GPU optimization of lattice Boltzmann method with local ensemble transform Kalman filter

Hasegawa, Yuta; Imamura, Toshiyuki*; Ina, Takuya; Onodera, Naoyuki; Asahi, Yuichi; Idomura, Yasuhiro

Proceedings of 13th Workshop on Latest Advances in Scalable Algorithms for Large-Scale Heterogeneous Systems (ScalAH22) (Internet), p.10 - 17, 2022/00

The ensemble data assimilation of computational fluid dynamics simulations based on the lattice Boltzmann method (LBM) and the local ensemble transform Kalman filter (LETKF) is implemented and optimized on a GPU supercomputer based on NVIDIA A100 GPUs. To connect the LBM and LETKF parts, data transpose communication is optimized by overlapping computation, file I/O, and communication based on data dependency in each LETKF kernel. In two dimensional forced isotropic turbulence simulations with the ensemble size of $$M=64$$ and the number of grid points of $$N_x=128^2$$, the optimized implementation achieved $$times3.85$$ speedup from the naive implementation, in which the LETKF part is not parallelized. The main computing kernel of the local problem is the eigenvalue decomposition (EVD) of $$Mtimes M$$ real symmetric dense matrices, which is computed by a newly developed batched EVD in EigenG. The batched EVD in EigenG outperforms that in cuSolver, and $$times64$$ speedup was achieved.

Journal Articles

Tree cutting approach for domain partitioning on forest-of-octrees-based block-structured static adaptive mesh refinement with lattice Boltzmann method

Hasegawa, Yuta; Aoki, Takayuki*; Kobayashi, Hiromichi*; Idomura, Yasuhiro; Onodera, Naoyuki

Parallel Computing, 108, p.102851_1 - 102851_12, 2021/12

 Times Cited Count:10 Percentile:53.91(Computer Science, Theory & Methods)

The aerodynamics simulation code based on the lattice Boltzmann method (LBM) using forest-of-octrees-based block-structured local mesh refinement (LMR) was implemented, and its performance was evaluated on GPU-based supercomputers. We found that the conventional Space-Filling-Curve-based (SFC) domain partitioning algorithm results in costly halo communication in our aerodynamics simulations. Our new tree cutting approach improved the locality and the topology of the partitioned sub-domains and reduced the communication cost to one-third or one-fourth of the original SFC approach. In the strong scaling test, the code achieved maximum $$times1.82$$ speedup at the performance of 2207 MLUPS (mega- lattice update per second) on 128 GPUs. In the weak scaling test, the code achieved 9620 MLUPS at 128 GPUs with 4.473 billion grid points, while the parallel efficiency was 93.4% from 8 to 128 GPUs.

JAEA Reports

Evaluation of the minimum critical amount for heterogeneous lattice systems composed of fuel rods utilized in low-power water-moderated research and test reactors by using continuous-energy Monte Carlo code MVP with JENDL-4.0

Yanagisawa, Hiroshi

JAEA-Technology 2021-023, 190 Pages, 2021/11

JAEA-Technology-2021-023.pdf:5.25MB

Computational analyses on nuclear criticality characteristics were carried out for heterogeneous lattice systems composed of water moderator and fuel rods utilized in low-power research and test reactors, in which the depletion of fuel due to burnup is relatively small, by using the continuous-energy Monte Carlo code MVP Version 2 with the evaluated nuclear data library JENDL-4.0. In the analyses, the minimum critical number of fuel rods was evaluated using calculated neutron multiplication factors for the heterogeneous systems of the uranium dioxide fuel rod in the Static Experiments Critical Facility (STACY) and the Tank-type Critical Assembly (TCA), and the uranium-zirconium hydride fuel rod in the Nuclear Safety Research Reactor (NSRR). In addition, six sorts of the ratio of reaction rates, which are components of neutron multiplication factors, were calculated in the analyses to explain the variation of neutron multiplication factors with the ratio of water moderator to fuel volume in a unit fuel rod cell. Those results of analyses are considered to be useful for the confirmation of reasonableness and validity of criticality safety measures as data showing criticality characteristics for water-moderated heterogeneous lattice systems composed of the existing fuel rods in research and test reactors, of which criticality data are not sufficiently provided by the Criticality Safety Handbook.

Journal Articles

Anisotropic thermal lattice expansion and crystallographic structure of strontium aluminide within Al-10Sr alloy as measured by in-situ neutron diffraction

Liss, K.-D.*; Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya; Xu, P. G.

Journal of Alloys and Compounds, 869, p.159232_1 - 159232_9, 2021/07

AA2020-0822.pdf:1.94MB

 Times Cited Count:7 Percentile:28.62(Chemistry, Physical)

207 (Records 1-20 displayed on this page)