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Journal Articles

In situ reaction and alteration of mudstone-cement interfaces at the Horonobe URL; Comparison between ordinary Portland cement and low alkaline cement

Dei, Shuntaro; Shibata, Masahito*; Negishi, Kumi*; Sugiura, Yuki; Amano, Yuki; Bateman, K.*; Wilson, J.*; Yokoyama, Tatsunori; Kagami, Saya; Takeda, Masaki; et al.

Results in Earth Sciences (Internet), 3, p.100097_1 - 100097_16, 2025/12

Interactions between cement and host rock in geological repositories for radioactive waste will result in a chemically disturbed zone, which may potentially affect the long-term safety. This paper investigates the chemical evolution at the interface between cement (Ordinary Portland Cement: OPC and Low Alkaline Cement: LAC) and mudstone after 11 years of in situ reactions at the Horonobe Underground Research Laboratory. The study combines various analytical techniques to identify the key reactions at the cement-rock interface, including cement dissolution, precipitation of secondary minerals such as calcite and C-(A-)S-H phases, cation exchange in montmorillonite and reduced porosity in mudstone. The study also highlights the effects of cement-mudstone interactions on radionuclide migration, such as reduction of diffusivity due to reduced porosity and enhancement of sorption due to incorporation into secondary minerals in the altered mudstone.

Journal Articles

Investigating eutectic behavior and material relocation in B$$_{4}$$C-stainless steel composites using the improved MPS method

Ahmed, Z.*; Wu, S.*; Sharma, A.*; Kumar, R.*; Yamano, Hidemasa; Pellegrini, M.*; Yokoyama, Ryo*; Okamoto, Koji*

International Journal of Heat and Mass Transfer, 250, p.127343_1 - 127343_17, 2025/11

 Times Cited Count:0

Journal Articles

Influence of steam flow rate on oxidation kinetics of silicon carbide at 1400-1600 $$^{circ}$$C

Pham, V. H.; Kurata, Masaki; Nagae, Yuji; Ishibashi, Ryo*; Sasaki, Masana*

Corrosion Science, 255, p.113098_1 - 113098_9, 2025/10

 Times Cited Count:0

Journal Articles

A Simplified quantification method for seismic risk assessment of nuclear fuel cycle facilities using Clark approximation

Kubo, Kotaro; Mori, Kenji*; Muramatsu, Ken

Nuclear Engineering and Design, 442, p.114176_1 - 114176_14, 2025/10

 Times Cited Count:0

Journal Articles

High-temperature oxidation failure in reactivity-initiated accidents; An Evaluation of failure criteria based on oxygen concentration from the previous NSRR experiments

Luu, V. N.; Taniguchi, Yoshinori; Udagawa, Yutaka; Katsuyama, Jinya

Nuclear Engineering and Design, 442, p.114222_1 - 114222_15, 2025/10

 Times Cited Count:0

Journal Articles

Composition dependence of the anomalous Nernst effect in Fe$$_{4-x}$$Mn$$_{x}$$N and Fe$$_{4-y}$$Co$$_{y}$$N films

Yin, W.*; Ito, Keita*; Tsubowa, Yusuke*; Tsujikawa, Masahito*; Shirai, Masafumi*; Umetsu, Rie*; Takanashi, Koki

Journal of Magnetism and Magnetic Materials, 628, p.173157_1 - 173157_8, 2025/09

 Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)

Journal Articles

Enhanced work hardening in ferrite and austenite of duplex stainless steel at 200 K; ${it In situ}$ neutron diffraction study

Yamashita, Takayuki*; Koga, Norimitsu*; Mao, W.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Fujii, Hidetoshi*; Umezawa, Osamu*

Materials Science and Engineering A, 941, p.148602_1 - 148602_11, 2025/09

 Times Cited Count:0

Journal Articles

Microstructural evolution and mechanical instability of Mar-M509 superalloy fabricated by laser powder bed fusion under short-term thermal exposure

Cao, T.*; Wei, D.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; 10 of others*

Materials Science and Engineering A, 940, p.148534_1 - 148534_16, 2025/09

Journal Articles

Impact of molybdenum on iodine chemistry during fission product transport phenomenology

Rizaal, M.; Nakajima, Kunihisa; Suzuki, Eriko; Miwa, Shuhei

Annals of Nuclear Energy, 218, p.111433_1 - 111433_10, 2025/08

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

Journal Articles

Modeling the extraction of bound rubber from silica-filled styrene-butadiene rubber with toluene

Tamura, Yukiko*; Arakawa, Masato*; Takenaka, Mikihito*; Nakanishi, Yohei*; Fujinami, So*; Shibata, Motoki*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Yamada, Masako*; Seto, Hideki*; et al.

Polymer, 333, p.128662_1 - 128662_8, 2025/08

 Times Cited Count:0

JAEA Reports

Analysis of the radioactivity concentrations in radioactive waste stored at the Waste Storage Facility L as compressed packages

Aono, Ryuji; Goto, Katsunori*; Kinase, Akari; Sato, Yoshiyuki; Haraga, Tomoko; Iseda, Hirokatsu

JAEA-Data/Code 2025-006, 24 Pages, 2025/07

JAEA-Data-Code-2025-006.pdf:1.05MB

Radioactive wastes generated from nuclear research facilities in Japan Atomic Energy Agency are planned to be buried in the near surface disposal field as trench and pit. Therefore, it is required to establish the method to evaluate the radioactivity concentrations of radioactive wastes until the beginning of disposal. In order to contribute to this work, we collected and analyzed the samples stored at the waste storage facility L. In this report, we summarized the radioactivity concentrations of 12 radionuclides ($$^{3}$$H, $$^{14}$$C, $$^{60}$$Co, $$^{90}$$Sr, $$^{94}$$Nb, $$^{137}$$Cs, $$^{152}$$Eu, $$^{154}$$Eu, $$^{238}$$Pu, $$^{239}$$Pu, $$^{240}$$Pu, $$^{241}$$Am) which were obtained from radiochemical analysis of the samples in fiscal year 2020.

Journal Articles

Integrated thermal power measurement in the modified STACY for the performance inspections

Araki, Shohei; Aizawa, Eiju; Murakami, Takahiko; Arakaki, Yu; Tada, Yuta; Kamikawa, Yutaka; Hasegawa, Kenta; Yoshikawa, Tomoki; Sumiya, Masato; Seki, Masakazu; et al.

Annals of Nuclear Energy, 217, p.111323_1 - 111323_8, 2025/07

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

JAEA has modified the STACY from a homogeneous system using solution fuel to a heterogeneous system using fuel rods in order to obtain criticality characteristics of fuel debris. The modification of the STACY was completed in December 2023. A series of performance inspections were conducted for the start of experimental operations. A new thermal power calibration is required for the performance inspections in order to operate at less than 200 W, which is the permitted thermal power. However, the thermal power measurement method and calibration data used in the former STACY is no longer available due to the modification of the modified STACY. We measured the thermal power of the STACY using the activation method that was improved to adapt to the measurement condition and calibrated the power meter system. Since the positions where activation foils could be installed were very limited, the thermal power was evaluated using numerical calculations supplemented by experimental data. Neutron flux data at the positions of the activation foil was measured by the activation method. Neutron distribution in the core was calculated by the Monte Carlo code MVP. A response function of the activation foil was calculated using the PHITS. The uncertainty of the thermal power measurement was conservatively estimated to be about 15%. Four operations were conducted for the thermal power measurement. The power meter was calibrated by using three operational data and tested with the one operational data. It was found that the indicated value of the meter adjusted by the STACY before the modification work would tend to overestimate the actual output by about 40%. In addition, the current calibration was able to calibrate the meter to within 3% accuracy.

Journal Articles

Long-term changes in the chemical, microstructural, and transport properties of a low-pH cement shotcrete during operation of the Horonobe Underground Research Laboratory, Japan

Mochizuki, Akihito; Matsui, Hiroya; Nakayama, Masashi; Sakamoto, Ryo*; Shibata, Masahito*; Motoshima, Takayuki*; Jo, Mayumi*

Case Studies in Construction Materials, 22, p.e04648_1 - e04648_20, 2025/07

 Times Cited Count:0 Percentile:0.00(Construction & Building Technology)

The properties of low-pH cement used in the geological disposal of radioactive waste may change through atmospheric carbonation and degradation caused by groundwater during the long-term operation of a repository. In this study, we investigated the effects of atmospheric carbonation and groundwater contact on the chemical, microstructural, and transport properties of shotcrete made from low-pH, high-fly-ash silica-fume cement (HFSC) over a period of 16 years in an underground research laboratory. In both carbonated and degraded zones of the HFSC shotcrete, capillary porosity increased for pores of $$<$$300 nm in diameter, and the total porosity was higher than in undegraded zones. These changes in porosity may be associated with the decalcification of calcium-silicate-hydrate and decomposition of ettringite. Such changes were minor in altered zones of OPC shotcrete, indicating that HFSC shotcrete is less resistant to atmospheric carbonation and groundwater leaching under the studied conditions. However, the hydraulic conductivity in HFSC was low enough to fulfill the specific functional requirements of low-pH cements for geological disposal.

Journal Articles

Experimental and modeling studies on the oxygen ingression behavior at the crevices of stainless steels in high-temperature water

Soma, Yasutaka; Komatsu, Atsushi; Kaji, Yoshiyuki; Yamamoto, Masahiro*; Igarashi, Takahiro

Corrosion Science, 251, p.112897_1 - 112897_15, 2025/07

 Times Cited Count:1 Percentile:0.00(Materials Science, Multidisciplinary)

Experimental and modeling studies of the oxygen ingression at the crevices of stainless steels were conducted in high-temperature water (288$$^{circ}$$C). The limiting distance of oxygen ingression, $$d_{rm lim}$$, was defined as the point beyond which the primary surface oxide changed (hematite $$rightarrow$$ magnetite), regardless of crevice gap, oxygen concentration, and time. In situ measurements revealed increased electrical conductivity around the $$d_{rm lim}$$ position indicating ion enrichment due to a differential oxygen concentration cell. $$d_{rm lim}$$ increased with increasing crevice gap, oxygen concentration, and immersion time. Modeling study suggested that oxide layer growth reduced anodic dissolution and slowed oxygen consumption, allowing oxygen ingression with time.

Journal Articles

Which radionuclides contribute most to seafood ingestion dose?

Johansen, M. P.*; Gwynn, J. P.*; Carpenter, J. G.*; Charmasson, S.*; Mori, Airi; Orr, B.*; Simon-Cornu, M.*; Osvath, I.*; McGinnity, P.*

Journal of Environmental Radioactivity, 287, p.107706_1 - 107706_8, 2025/07

 Times Cited Count:0 Percentile:0.00(Environmental Sciences)

Journal Articles

Temperature-dependent deformation behavior of dual-phase medium-entropy alloy; In-situ neutron diffraction study

Gu, G. H.*; Jeong, S. G.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Cho, J.*; Kim, H. S.*; 4 of others*

Journal of Materials Science & Technology, 223, p.308 - 324, 2025/07

 Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)

Journal Articles

Unique deformation behavior of ultrafine-grained 304 stainless steel at 20 K

Mao, W.*; Gong, W.; Kawasaki, Takuro; Gao, S.*; Ito, Tatsuya; Yamashita, Takayuki*; Harjo, S.; Zhao, L.*; Wang, Q.*

Scripta Materialia, 264, p.116726_1 - 116726_6, 2025/07

 Times Cited Count:0 Percentile:0.00(Nanoscience & Nanotechnology)

Journal Articles

Complementary layer thickness effects of Q235 and SUS304 layers of multilayered steels for improving of tensile strength and plasticity simultaneously

Lin, Z. M.*; Liu, B. X.*; Ming, K. S.*; Xu, P. G.; Yin, F. X.*; Zheng, S. J.*

Scripta Materialia, 263, p.116692_1 - 116692_7, 2025/07

 Times Cited Count:0 Percentile:0.00(Nanoscience & Nanotechnology)

Journal Articles

Grain refinement of dual phase steel maximizes deformation ability of martensite, leading to simultaneous enhancement of strength and ductility

Park, M.-H.*; Shibata, Akinobu*; Harjo, S.; Tsuji, Nobuhiro*

Acta Materialia, 292, p.121061_1 - 121061_13, 2025/06

 Times Cited Count:1 Percentile:84.88(Materials Science, Multidisciplinary)

Journal Articles

Methods for regulating depth of corrosion fissures in simulated fastener holes of 7050-T7451 aluminum alloy

Aoyama, Takahito; Choudhary, S.*; Pandaleon, A.*; Burns, J. T.*; Kokaly, M.*; Restis, J.*; Ross, J.*; Kelly, R. G.*

Corrosion, 81(6), p.609 - 621, 2025/06

42828 (Records 1-20 displayed on this page)