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Journal Articles

Toward mechanistic evaluation of critical heat flux in nuclear reactors, 2; Recent studies and future challenges toward mechanistic and reliable CHF evaluation

Okawa, Tomio*; Mori, Shoji*; Liu, W.*; Ose, Yasuo*; Yoshida, Hiroyuki; Ono, Ayako

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 63(12), p.820 - 824, 2021/12

The evaluation method of the critical heat flux based on the mechanism is needed for the efficient design and development of fuel in reactors and the appropriate safety evaluation. In this paper, the current researches relating to the mechanism of the critical heat flux are reviewed, and the issue to be considered in the future are discussed.

Journal Articles

Comparisons between passive RCCSS on degree of passive safety features against accidental conditions and methodology to determine structural thickness of scaled-down heat removal test facilities

Takamatsu, Kuniyoshi; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*

Annals of Nuclear Energy, 162, p.108512_1 - 108512_10, 2021/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The objectives of this study are as follows: to understand the characteristics, degree of passive safety features for heat removal were compared for RCCSs based on atmospheric radiation and based on atmospheric natural circulation under the same conditions. Next, simulations on accidental conditions, such as increasing average heat-transfer coefficient via natural convection due to natural disasters, were performed with STAR-CCM+, and methodology to control the amount of heat removal was discussed. As a result, a new RCCS based on atmospheric radiation is recommended because of the excellent degree of passive safety features/conditions, and the amount of heat removal by heat transfer surfaces which can be controlled. Finally, methodology to determine structural thickness of scaled-down heat removal test facilities for reproducing natural convection and radiation was developed, and experimental methods by using pressurized and decompressed chambers was also proposed.

Journal Articles

The $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross section from the surrogate ratio method and its effect on the $$^{60}$$Fe nucleosynthesis

Yan, S. Q.*; Li, X. Y.*; Nishio, Katsuhisa; Lugaro, M.*; Li, Z. H.*; Makii, Hiroyuki; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; Hirose, Kentaro; et al.

Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10

 Times Cited Count:0

Journal Articles

A 3D particle-based analysis of molten pool-to-structural wall heat transfer in a simulated fuel subassembly

Zhang, T.*; Morita, Koji*; Liu, X.*; Liu, W.*; Kamiyama, Kenji

Extended abstracts of the 2nd Asian Conference on Thermal Sciences (Internet), 2 Pages, 2021/10

For the Japanese sodium cooled fast reactor, a fuel subassembly with an inner duct structure (FAIDUS) was designed to avoid the re-criticality by preventing the large-scale pool formation. In the present study, using the finite volume particle method, the EAGLE ID1 test which was an in-pile test performed to demonstrate the effectiveness of FAIDUS was numerically simulated and the thermal-hydraulic mechanisms underlying the heat transfer process were analyzed.

Journal Articles

Investigation of the ground-state spin inversion in the neutron-rich $$^{47,49}$$Cl isotopes

Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; G$'o$mez-Ramos, M.*; et al.

Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10

no abstracts in English

Journal Articles

Evaluation report of Task 9B based on comparisons and analyses of modelling results for the $"A$sp$"o$ HRL LTDE-SD experiments

Soler, J. M.*; Meng, S.*; Moreno, L.*; Neretnieks, I.*; Liu, L.*; Kek$"a$l$"a$inen, P.*; Hokr, M.*; $v{R}$$'i$ha, J.*; Vete$v{s}$n$'i$k, A.*; Reimitz, D.*; et al.

SKB TR-20-17, 71 Pages, 2021/07

Task 9B of the SKB Task Force on Modelling of Groundwater Flow and Transport of Solutes in fractured rock focused on the modelling of experimental results from the LTDE-SD in situ tracer test performed at the $"A$sp$"o$ Hard Rock Laboratory in Sweden. Ten different modelling teams provided results for this exercise, using different concepts and codes. Three main types of modelling approaches were used: (1) analytical solutions to the transport-retention equations, (2) continuum-porous-medium numerical models, and (3) microstructure-based models accounting for small-scale heterogeneity (i.e. mineral grains and microfracture distributions). The modelling by the different teams allowed the comparison of many different model concepts, especially in terms of potential zonations of rock properties (porosity, diffusion, sorption), such as the presence of a disturbed zone at the rock and fracture surface, the potential effects of micro- and cm-scale fractures.

Journal Articles

Pairing forces govern population of doubly magic $$^{54}$$Ca from direct reactions

Browne, F.*; Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Ogata, Kazuyuki*; Utsuno, Yutaka; Yoshida, Kazuki; Achouri, N. L.*; Baba, Hidetada*; Calvet, D.*; et al.

Physical Review Letters, 126(25), p.252501_1 - 252501_7, 2021/06

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Direct proton-knockout reactions of $$^{55}$$Sc were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of $$^{54}$$Ca were investigated through $$gamma$$-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological inter-nucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of $$^{55}$$Sc, valence proton removals populated predominantly the ground-state of $$^{54}$$Ca. This counter-intuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.

Journal Articles

First spectroscopic study of $$^{51}$$Ar by the ($$p$$,2$$p$$) reaction

Juh$'a$sz, M. M.*; Elekes, Z.*; Sohler, D.*; Utsuno, Yutaka; Yoshida, Kazuki; Otsuka, Takaharu*; Ogata, Kazuyuki*; Doornenbal, P.*; Obertelli, A.*; Baba, Hidetada*; et al.

Physics Letters B, 814, p.136108_1 - 136108_8, 2021/03

 Times Cited Count:1 Percentile:74.98(Astronomy & Astrophysics)

The nuclear structure of $$^{51}$$Ar was studied by the ($$p$$,2$$p$$) reaction using $$gamma$$-ray spectroscopy for the bound and unbound states. Comparing the results to our shell-model calculations, two bound and six unbound states were established. The low cross sections populating the two bound states of $$^{51}$$Ar could be interpreted as a clear signature for the presence of significant sub-shell closures at neutron numbers 32 and 34 in argon isotopes.

Journal Articles

Suppressed lattice disorder for large emission enhancement and structural robustness in hybrid lead iodide perovskite discovered by high-pressure isotope effect

Kong, L.*; Gong, J.*; Hu, Q.*; Capitani, F.*; Celeste, A.*; Hattori, Takanori; Sano, Asami; Li, N.*; Yang, W.*; Liu, G.*; et al.

Advanced Functional Materials, 31(9), p.2009131_1 - 2009131_12, 2021/02

 Times Cited Count:1 Percentile:24.67(Chemistry, Multidisciplinary)

The soft nature of organic-inorganic halide perovskites renders their lattice particularly tunable to external stimuli such as pressure, undoubtedly offering an effective way to modify their structure for extraordinary optoelectronic properties. However, these soft materials meanwhile feature a general characteristic that even a very mild pressure will lead to detrimental lattice distortion and weaken the critical light-matter interaction, thereby triggering the performance degradation. Here, using the methylammonium lead iodide as a representative exploratory platform, we observed the pressure-driven lattice disorder can be significantly suppressed via hydrogen isotope effect, which is crucial for better optical and mechanical properties previously unattainable.

Journal Articles

Comparison between passive reactor cavity cooling systems based on atmospheric radiation and atmospheric natural circulation

Takamatsu, Kuniyoshi; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*

Annals of Nuclear Energy, 151, p.107867_1 - 107867_11, 2021/02

 Times Cited Count:1 Percentile:81.22(Nuclear Science & Technology)

A new RCCS with passive safety features consists of two continuous closed regions. One is a region surrounding RPV. The other is a cooling region with heat transferred to the ambient air. The new RCCS needs no electrical or mechanical driving devices. We compared the RCCS using atmospheric radiation with that using atmospheric natural circulation in terms of passive safety features and control methods for heat removal. The magnitude relationship for passive safety features is heat conduction $$>$$ radiation $$>$$ natural convection. Therefore, the magnitude for passive safety features of the former RCCS can be higher than that of the latter RCCS. In controlling the heat removal, the former RCCS changes the heat transfer area only. On the other hand, the latter RCCS needs to change the chimney effect. It is necessary to change the air resistance in the duct. Therefore, the former RCCS can control the heat removal more easily than the latter RCCS.

Journal Articles

Stacking fault driven phase transformation in CrCoNi medium entropy alloy

He, H.*; Naeem, M.*; Zhang, F.*; Zhao, Y.*; Harjo, S.; Kawasaki, Takuro; Wang, B.*; Wu, X.*; Lan, S.*; Wu, Z.*; et al.

Nano Letters, 21(3), p.1419 - 1426, 2021/02

 Times Cited Count:3 Percentile:0(Chemistry, Multidisciplinary)

Journal Articles

Numerical simulation of heat transfer behavior in EAGLE ID1 in-pile test using finite volume particle method

Zhang, T.*; Funakoshi, Kanji*; Liu, X.*; Liu, W.*; Morita, Koji*; Kamiyama, Kenji

Annals of Nuclear Energy, 150, p.107856_1 - 107856_10, 2021/01

 Times Cited Count:1 Percentile:81.22(Nuclear Science & Technology)

Journal Articles

Formation of $$alpha$$ clusters in dilute neutron-rich matter

Tanaka, Junki*; Yang, Z.*; Typel, S.*; Adachi, Satoshi*; Bai, S.*; Van Beek, P.*; Beaumel, D.*; Fujikawa, Yuki*; Han, J.*; Heil, S.*; et al.

Science, 371(6526), p.260 - 264, 2021/01

 Times Cited Count:8 Percentile:99.26(Multidisciplinary Sciences)

By employing quasi-free $$alpha$$-cluster-knockout reactions, we obtained direct experimental evidence for the formation of $$alpha$$ clusters at the surface of neutron-rich tin isotopes. The observed monotonous decrease of the reaction cross sections with increasing mass number, in excellent agreement with the theoretical prediction, implies a tight interplay between $$alpha$$-cluster formation and the neutron skin.

Journal Articles

General synthesis of single-atom catalysts for hydrogen evolution reactions and room-temperature Na-S batteries

Lai, W.-H.*; Wang, H.*; Zheng, L.*; Jiang, Q.*; Yan, Z.-C.*; Wang, L.*; Yoshikawa, Hirofumi*; Matsumura, Daiju; Sun, Q.*; Wang, Y.-X.*; et al.

Angewandte Chemie; International Edition, 59(49), p.22171 - 22178, 2020/12

 Times Cited Count:16 Percentile:89.25(Chemistry, Multidisciplinary)

Journal Articles

$$N$$ = 32 shell closure below calcium; Low-lying structure of $$^{50}$$Ar

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Men$'e$ndez, J.*; Ogata, Kazuyuki*; Schwenk, A.*; Shimizu, Noritaka*; Simonis, J.*; et al.

Physical Review C, 102(6), p.064320_1 - 064320_9, 2020/12

 Times Cited Count:1 Percentile:35.83(Physics, Nuclear)

Low-lying excited states in the $$N$$ = 32 isotope $$^{50}$$Ar were investigated by in-beam $$gamma$$-ray spectroscopy following proton- and neutron-knockout, multinucleon removal, and proton inelastic scattering at the RIKEN Radioactive Isotope Beam Factory. The energies of the two previously reported transitions have been confirmed, and five additional states are presented for the first time, including a candidate for a 3$$^{-}$$ state. The level scheme built using $$gamma$$ $$gamma$$ coincidences was compared to shell-model calculations in the $$sd-pf$$ model space and to ${it ab initio}$ predictions based on chiral two- and three-nucleon interactions. Theoretical proton- and neutron-knockout cross sections suggest that two of the new transitions correspond to 2$$^{+}$$ states, while the previously proposed 4$$^{+}_{1}$$ state could also correspond to a 2$$^{+}$$ state.

Journal Articles

Element effects of Mn and Ge on the tuning of mechanical properties of high-entropy alloys

Lam, T.-N.*; Tsai, C.-W.*; Chen, B.-K.*; Lai, B.-H.*; Liu, H.-C*; Kawasaki, Takuro; Harjo, S.; Lin, B.-H.*; Huang, E.-W.*

Metallurgical and Materials Transactions A, 51(10), p.5023 - 5028, 2020/10

 Times Cited Count:3 Percentile:59.43(Materials Science, Multidisciplinary)

Journal Articles

Shell evolution of $$N$$ = 40 isotones towards $$^{60}$$Ca; First spectroscopy of $$^{62}$$Ti

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Men$'e$ndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.

Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01

 Times Cited Count:13 Percentile:97.21(Astronomy & Astrophysics)

Excited states in the $$N$$ = 40 isotone $$^{62}$$Ti were populated via the $$^{63}$$V($$p$$,$$2p$$)$$^{62}$$Ti reaction at $$sim$$200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using $$gamma$$-ray spectroscopy. The energies of the $$2_1^+ rightarrow 0_{rm gs}^+$$ and $$4_1^+ rightarrow 2_1^+$$ transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring $$^{64}$$Cr and $$^{66}$$Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.

Journal Articles

Fine structure in the $$alpha$$ decay of $$^{223}$$U

Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.

Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01

 Times Cited Count:6 Percentile:89.19(Astronomy & Astrophysics)

Journal Articles

Comparative methodology between actual RCCS and downscaled heat-removal test facility

Takamatsu, Kuniyoshi; Matsumoto, Tatsuya*; Liu, W.*; Morita, Koji*

Annals of Nuclear Energy, 133, p.830 - 836, 2019/11

 Times Cited Count:2 Percentile:42.44(Nuclear Science & Technology)

A RCCS having passive safety features through radiation and natural convection was proposed. The RCCS design consists of two continuous closed regions: an ex-reactor pressure vessel region and a cooling region with a heat-transfer surface to ambient air. The RCCS uses a novel shape to remove efficiently the heat released from the RPV through as much radiation as possible. Employing air as the working fluid and ambient air as the ultimate heat sink, the RCCS design can strongly reduce the possibility of losing the working fluid and the heat sink for decay-heat-removal. Moreover, the authors started experiment research with using a scaled-down heat-removal test facility. Therefore, this study propose a comparative methodology between an actual RCCS and a scaled-down heat-removal test facility.

Journal Articles

Quasifree neutron knockout from $$^{54}$$Ca corroborates arising $$N=34$$ neutron magic number

Chen, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Chazono, Yoshiki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Raimondi, F.*; et al.

Physical Review Letters, 123(14), p.142501_1 - 142501_7, 2019/10

AA2019-0306.pdf:0.57MB

 Times Cited Count:21 Percentile:92.26(Physics, Multidisciplinary)

no abstracts in English

173 (Records 1-20 displayed on this page)