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Gunji, Satoshi; Araki, Shohei; Izawa, Kazuhiko; Suyama, Kenya
Annals of Nuclear Energy, 209, p.110783_1 - 110783_7, 2024/12
Since the compositions and properties of the fuel debris are uncertain, critical experiments are required to validate calculation codes and nuclear data used for the safety evaluation. For this purpose, the Japan Atomic Energy Agency (JAEA) has been modifying a critical assembly called "STACY." The first criticality of the modified STACY is scheduled for spring 2024. This paper reports the consideration results of the specifications of the basic core configurations of the modified STACY at the first criticality. We prepared two types of gird plates with different neutron moderation conditions (their intervals are 1.50 cm and 1.27 cm). However, there is a limitation on the number of available UO
fuel rods. The core configurations for the first criticality satisfying these experimental constraints were designed by computational analysis. A cylindrical core configuration with a 1.50 cm grid plate close to the optimum moderation condition needs 253 fuel rods to reach criticality. As to the 1.27 cm grid plate, we considered core configurations with 2.54 cm intervals by using doubled pitches of the grid plate. It will need 213 fuel rods for the criticality. In addition, we considered the experimental core configuration with steel/concrete simulant rods to simulate fuel debris conditions. This paper shows these core configurations and their evaluated specifications.
Fukuda, Kodai
Annals of Nuclear Energy, 208(1), p.110748_1 - 110748_10, 2024/12
Miura, Taito*; Miyamoto, Shintoro*; Maruyama, Ippei*; Aili, A.*; Sato, Takumi; Nagae, Yuji; Igarashi, Go*
Case Studies in Construction Materials, 21, p.e03571_1 - e03571_14, 2024/12
Sm synchrotron-radiation-based M
ssbauer and 
SR studies of Sm
Ru
Ge
Tsutsui, Satoshi; Ito, Takashi; Nakamura, Jin*; Yoshida, Mio*; Kobayashi, Yoshio*; Yoda, Yoshitaka*; Nakamura, Jumpei*; Koda, Akihiro*; Higashinaka, Ryuji*; Aoki, Dai*; et al.
Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12
Sm synchrotron-radiation-based Mssbauer spectroscopy of Sm-based heavy fermion compoundsTsutsui, Satoshi; Higashinaka, Ryuji*; Mizumaki, Masaichiro*; Kobayashi, Yoshio*; Nakamura, Jin*; Ito, Takashi; Yoda, Yoshitaka*; Matsuda, Tatsuma*; Aoki, Yuji*; Sato, Hideyuki*
Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12
Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Sunagawa, Hikaru*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Fujihara, Masayoshi; Tampo, Motonobu*; Kawamura, Naritoshi*; et al.
Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12
)
(SrAl
TaO)
with 
Ito, Takashi; Higemoto, Wataru; Koda, Akihiro*; Nakamura, Jumpei*; Shimomura, Koichiro*
Interactions (Internet), 245(1), p.25_1 - 25_7, 2024/12
SR studies on copper mineralsFujihara, Masayoshi; Okabe, Hirotaka*; Koda, Akihiro*
Interactions (Internet), 245(1), p.13_1 - 13_6, 2024/12
Quantum states are difficult to observe experimentally. In addition, ideal model materials have not been found for some of the lattice systems in which exotic quantum states are predicted to be realized. Numerous candidates for low-dimensional quantum magnets are hidden in copper minerals, and the number of candidates is increasing every year. We succeeded to synthesize seven copper minerals by imitating the environment where they are discovered and reported their quantum states. The properties of pulsed muons are very suitable for investigating the spin state of artificial copper minerals.
Okada, Kazuho*; Shibata, Akinobu*; Kimura, Yuji*; Yamaguchi, Masatake; Ebihara, Kenichi; Tsuji, Nobuhiro*
Acta Materialia, 280, p.120288_1 - 120288_14, 2024/11
= 0.01-600
C, 
= 1-3000 bars, 
= 0.35-1.1 g cm
, and 
= 0
Walker, C. S.*; Arthur, R. C.*; Anraku, Sohtaro; Sasamoto, Hiroshi; Mihara, Morihiro
Applied Geochemistry, 175, p.106086_1 - 106086_17, 2024/11
The thermodynamic properties and revised Helgeson-Kirkham-Flowers equation of state (r-H-K-F EoS) parameters of the hydrated (Si(OH)
(aq), SiO(OH)
and SiO(OH)
) and fictive dehydrated (SiO(aq), HSiO and SiO) monomeric silicon species are used extensively to describe the pH, composition, temperature, and pressure dependence of formation/breakdown reactions of all silicon-bearing compounds globally. Experimental log10 equilbrium constant, K values describing the formation reactions of the hydrated and dehydrated monomeric silicon species were therefore compiled from the literature, extrapolated to zero ionic strength by specific ion interaction theory as required and used to derive their thermodynamic properties and r-H-K-F EoS parameters. Consideration of all formation reactions in the same study provides a collective, internally consistent update to the thermodynamic properties and r-H-K-F EoS parameters of the monomeric silicon species that can provide a satisfactory match to the experimental log10 K values at = 0.01-600C, = 1-3000 bars, = 0.35-1.1 g cm, and zero ionic strength. These temperature and pressure limits comfortably bracket t=0.01-100C and P =1-270 bars relecant to the geological disposal of radioactive wastes at depths of up to 1 km.
-HO system using deep neural networkTanaka, Nobuyuki; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Myagmarjav, O.; Ono, Masato; Sugimoto, Chihiro
Chemical Engineering Science, 299, p.120479_1 - 120479_11, 2024/11
We developed a deep neural network method to predict the composition of the iodine-sulfur process of thermochemical water-splitting hydrogen production using measurable properties. Unlike conventional titration analysis, this approach allows a quick understanding of fluid composition, providing essential information for controlling operating conditions. This study focused on the HI-I-HO three-component system within the IS process. Using Gibbs phase rule, the DNN model was constructed using online measurable parameters, such as temperature, pressure, and density, as input conditions. The model was trained with experimental data, and the structural parameters were tuned. Composition prediction using actual trend data demonstrated good correlation with titration analysis measurements. Furthermore, the local interpretable model-agnostic explanations method was incorporated to gain insights into the significance of input parameters for compositions from the DNN model, providing valuable information on crucial parameters for effective composition control.
Abe, Yosuke; Sasaki, Taisuke*; Yamashita, Shinichiro; Okubo, Nariaki; Ukai, Shigeharu
Journal of Nuclear Materials, 600, p.155271_1 - 155271_12, 2024/11
To investigate the formation behavior of Cr-rich precipitates (CrRP) in Fe-Cr-Al (ODS) alloys being developed as accident tolerant fuel cladding for light water reactors, 14 Fe-Cr-Al alloys with systematically varied Cr and Al compositions were irradiated with 10.5 MeV Fe
at 
C at three damage levels. A three-dimensional atom probe analysis showed that the CrRP number density, volume fraction, and Cr concentration increase with increasing Cr composition, decreasing Al composition, and decreasing dose rate. The result of the multiple regression analysis on CrRP volume fractions indicates that in addition to the primary effects of these variables, there are several important interactions. It was also highlighted that to understand the dose rate effect on the CrRP formation behavior under neutron irradiation, it is useful to examine the irradiation time dependence, including the effective use of thermal aging data as a limit to the zero dose rate.
Oguri, Kaori; Hagura, Naoto*; Yamaguchi, Akiko; Okumura, Masahiko; Matsuura, Haruaki*; Tsunashima, Yasumichi; Aoki, Katsumi; Arai, Yoichi; Watanabe, So
Nuclear Instruments and Methods in Physics Research B, 556, p.165516_1 - 165516_8, 2024/11
Ningyo-toge is the uranium mine that has been operated in Japan. Various radioactive elements such as Uranium (U), and Radium (Ra) are still present in the mine ground water with very small amount, and behavior of those elements is not fully understood. In this study, we investigated the composition of metal oxides and clay minerals in a soil of slag deposit at the mine, and systematics of adsorption structure of various ions were examined. Identifying the composition and chemical forms of minerals present in the soil of slag can provide useful information for the safety assessment and evaluation of influence on the surrounding environment.
Okita, Shoichiro; Abe, Yutaka*; Tasaki, Seiji*; Fukaya, Yuji
Radioisotopes, 73(3), p.233 - 240, 2024/11
Fujimura, Yuki; Ishikawa, Norito; Kondo, Keietsu
JAEA-Technology 2024-012, 26 Pages, 2024/10
JAEA-Technology-2024-012.pdf:3.03MB
While ceramic materials exhibit high temperature strength and corrosion resistance, they are also chemically stable. Specifically, aluminum oxide (AlO) is recognized as one of the highly radiation resistant materials. On the other hand, the precise evaluation of irradiation damage in these materials poses a significant challenge because detecting radiation damage induced in highly radiation-resistant ceramics is difficult. The objective of this study is to evaluate irradiation-induced lattice strain using Electron BackScatter Diffraction (EBSD), a technique commonly employed for damage analysis in metals. Ion irradiation tests were conducted on AlO, a representative highly radiation-resistant ceramic, at various doses. Through lattice strain analysis using EBSD, we successfully identified irradiation-induced lattice strain in the direction parallel to the irradiation, consistent with previous XRD analysis results. Lattice strain in the direction perpendicular to the irradiation was also detected. It was observed that the lattice strain tends to increase with increasing irradiation damage. In conclusion, lattice strain analysis using EBSD proves to be an effective method for assessing the irradiation effects on ceramics.
Aoki, Kazuhiro; Imai, Hirotaro; Seshimo, Kazuyoshi; Kimura, Megumi; Kirita, Fumio; Nakanishi, Ryuji
JAEA-Research 2024-005, 177 Pages, 2024/10
This study presents a method for evaluating displacements on active faults that lack clear markers of fault offset. The method uses geological surveys, core studies, and chemical analyses along with hydraulic and mechanical tests. We applied this method to three test sites along the Shionohira Fault (Shionohira and Betto sites) and the Kuruma Fault (Minakamikita site). Laboratory friction tests on the fault gouge using a variable-speed, rotating shear friction apparatus were conducted. The samples from the Shionohira and Betto sites showed velocity weakening or strengthening, but no velocity dependence was observed at the Minakamikita site. A small-scale test to induce fault slip was conducted using the SIMFIP method. At the Shionohira site, fault slip can be modeled as a Coulomb rupture and shows a frictional dependence on slip velocity. On the other hand, at the Minakamikita site, a complex response using multiple fractures and slip planes was observed. Based on the water pressure response, the hydraulic properties of the area between the faults were evaluated. The transmissivity and specific storage are larger at Shionohira than at Minakamikita. Fault slip data such as shear plane attitude or shear sense were obtained from core samples and stress inversion analysis was performed. We attempted to elucidate the history of the movement and stress that formed the fracture zone. The results reconstructed five activity stages at Shionohira site and two stages at Minakamikita site. As shown in this report, the frictional properties, fault rupture mode, hydraulic properties and the history of fault motion were found to be different between the Shionohira and Kuruma sites. However, the results are based on a few locational data, so case studies at other sites and more applications to other faults should be considered to improve the reliability of the evaluation.
Mao, W.*; Gao, S.*; Gong, W.; Kawasaki, Takuro; Ito, Tatsuya; Harjo, S.; Tsuji, Nobuhiro*
Acta Materialia, 278, p.120233_1 - 120233_13, 2024/10
Imaizumi, Yuya; Kamiyama, Kenji; Matsuba, Kenichi
Annals of Nuclear Energy, 206, p.110658_1 - 110658_10, 2024/10
Sato, Yuki
Applied Radiation and Isotopes, 212, p.111421_1 - 111421_8, 2024/10
Cl on Cu oxide Surfaces; CuO(111) and bulk CuO precursor "29"; Structure on Cu(111)Hayashida, Koki*; Tsuda, Yasutaka; Murase, Natsumi*; Yamada, Takashi*; Yoshigoe, Akitaka; Di
o, W. A.*; Okada, Michio*
Applied Surface Science, 669, p.160475_1 - 160475_6, 2024/10
