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Zhang, Y.*; Marusawa, Kenji*; Kudo, Kohei*; Morooka, Satoshi; Gong, W.; Harjo, S.; Miyamoto, Goro*; Furuhara, Tadashi*
Journal of Materials Science & Technology, 275, p.250 - 259, 2026/12
Times Cited Count：0Hamase, Erina; Kawamura, Takumi*; Doda, Norihiro; Tanaka, Masaaki
Annals of Nuclear Energy, 236, p.112358_1 - 112358_13, 2026/10
Times Cited Count：0To ensure the reliability of analysis results from the plant dynamics analysis code Super-COPD, a validation process comprising forward uncertainty quantification (Forward UQ) and sensitivity analysis (SA) using the Sobol method was developed. Uncertainty propagation analysis of input parameters was performed for the loss of flow without scram test in the FFTF and demonstrated that encompassing test results can serve as one measure validation criterion. Furthermore, SA identified dominant input parameters affecting uncertainty and provided effective targets for reducing uncertainty. This study confirms that Forward UQ and SA using the Sobol method are applicable for the validation process.
Hironaka, Kota; Koizumi, Mitsuo; Mochimaru, Takanori*; Takahashi, Tone; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*
Nuclear Instruments and Methods in Physics Research A, 1090, p.171675_1 - 171675_7, 2026/10
Times Cited Count：0Kosuge, Atsushi; Ando, Kota*; Yamamoto, Keisuke*; Nakajima, Takashi*
Optics & Laser Technology, 201, p.115269_1 - 115269_6, 2026/09
Times Cited Count：0 Percentile：0.00(Optics)Mano, Akihiro; Yamaguchi, Yoshihito; Katsuyama, Jinya
International Journal of Pressure Vessels and Piping, 222, p.105792_1 - 105792_11, 2026/08
Times Cited Count：0 Percentile：0.00(Engineering, Multidisciplinary)A probabilistic fracture mechanics (PFM) analysis code, PASCAL-SP, has been developed by the Japan Atomic Energy Agency (JAEA) to evaluate the failure probability of piping within nuclear power plants while considering age-related degradations such as stress corrosion cracking and fatigue for both pressurized water reactor and boiling water reactor environments. To strengthen the confidence in the results of PASCAL-SP, a benchmarking study was performed with the PFM analysis code, xLPR, which was developed by the U.S.NRC in collaboration with EPRI. In this benchmarking study, deterministic and probabilistic analyses are performed using common analysis conditions. This paper presents the details of these conditions and comparisons of the results between the two aforementioned codes. Both codes were found to provide nearly the same results in both deterministic and probabilistic analyses for a dissimilar metal weld subjected to primary water stress corrosion cracking.
Ha, Yoosung; Negyesi, M.*; Hasegawa, Kunio; Lacroix, V.*
Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems, 9(3), p.031001_1 - 031001_6, 2026/08
Negyesi, M.*; Hasegawa, Kunio
Journal of Pressure Vessel Technology, 148(4), p.044501_1 - 044501_4, 2026/08
Shi, W.*; Machida, Masahiko; Okamoto, Koji*; Luo, X.*; Feng, W.*; Liu, X.*
Reliability Engineering & System Safety, 272, Part1, p.112538_1 - 112538_18, 2026/08
The reliability of emergency response in severe nuclear accidents critically depends on robust real-time monitoring of radioactive source distributions. However, this safety function is challenged by physical constraints that create monitoring blind spots and by the inadequacy of static methods in tracking dynamic releases. To enhance the reliability and robustness of source term estimation, this study proposes a dynamic reconstruction framework based on LASSO regression with temporal regularization. A sliding-window time-penalty mechanism is introduced, imposing 
-norm constraints on inter-step source variations to ensure physical continuity. The contribution matrix and measurement vector are normalized to counteract biases from radiation shielding and time-varying intensities. Validation using a two-room model with internal shielding, with PHITS Monte Carlo simulation, demonstrates accurate reconstruction of dynamic sources from remote measurements. Temporal regularization enhances situational awareness by suppressing spatial aliasing: at sliding-window width 
(no regularization), hotspot locations fluctuate significantly, with quantitative mean absolute error fluctuations at around 
, whereas 
yields improved spatial consistency and the fluctuation quantities decrease to the 
range. Comparative analysis identifies 
as optimal in balancing accuracy and computational cost. This work establishes a more reliable pathway for dynamic hazard assessment, enabling accurate localization and intensity tracking under challenging conditions. The proposed framework provides a decision-support tool enhancing the resilience and safety of emergency management in nuclear facilities.
Abe, Takumi; Suzuki, Taiga*; Okamura, Tomohiro*; Nakase, Masahiko*
Annals of Nuclear Energy, 232, p.112224_1 - 112224_7, 2026/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Saga, Ryo*; Iwamori, Kenta*; Matsuya, Yusuke; Hosokawa, Yoichiro*
Computers in Biology and Medicine, 211, p.111743_1 - 111743_10, 2026/07
This study developed a biophysical model that integrates the characteristics of cancer stem cells (CSCs), including the side population (SP), and the oxygen enhancement effect (OER) to more accurately predict radiotherapy outcomes in prostate cancer. SP and main population (MP) cells were isolated from the DU145 prostate cancer cell line, and DNA double-strand breaks and survival were evaluated under both normoxic and hypoxic conditions (
0.1% O
). The obtained data were analyzed using the IMK model incorporating MP, SP, and oxygen concentration, and the predictions were compared with clinical tumor control probability (TCP) under various fractionation regimens (2, 3, and 7 Gy/Fx). As a result, the in vitro and clinical data were well reproduced by considering the MP/SP fraction, a population-independent OER, and the intratumoral hypoxic volume. Furthermore, the initial yield of DSBs was identified as a key determinant of radiosensitivity depending on cell characteristics and oxygen levels. The developed model is expected to contribute to the optimization of prostate cancer radiotherapy, including dose escalation to hypoxic tumor regions.
Yoshida, Naoki; Amano, Yuki; Yoshida, Ryoichiro; Ono, Takuya; Tashiro, Shinsuke; Yamane, Yuichi
Journal of Hazardous Materials, 513, p.142332_1 - 142332_20, 2026/07
Volatile ruthenium tetroxide (RuO
) formed during evaporation-to-dryness accidents (EDA) of high-level liquid waste (HLLW) combines high chemical toxicity with radiotoxicity from isotopes such as 
Ru and 
Ru, making it a primary hazard in nuclear-fuel reprocessing. This study experimentally elucidates the mechanisms governing RuO formation while testing the validity of the pragmatic nitrosyl-ruthenium ([RuNO]) surrogate model, an experimental model that assumes Ru in HLLW exists as [RuNO], and evaluates gaseous Ru release using nitric acid solutions of [RuNO], commonly used in RuO release assessments by comparing it with the behavior of simulated HLLW (s-HLLW). We systematically investigated potential pathways, including oxidation by liquid-phase nitric acid (HNO
(l)), gas-phase nitric acid (HNO(g)), and oxygen (O2); thermal decomposition of [RuNO]; and matrix effects of coexisting nitrates. The results identify oxidation by activated HNO(l), oxidation by HNO(g) and thermal decomposition of [RuNO] as the principal routes to RuO, with HNO(g) playing a far more significant role than previously recognized. Crucially, the RuO release profile from s-HLLW differed markedly from that predicted by the [RuNO] surrogate model, demonstrating that this model fails to capture the complex matrix effects and time-dependent chemical changes of Ru species inherent to real HLLW. These findings have significant implications for improving the accuracy of hazard assessments related to RuO release during HLLW EDAs, particularly by highlighting the limitations of commonly used [RuNO] surrogate models.
Sun, R.; Abe, Yukiko; Atarashi-Andoh, Mariko; Koarashi, Jun
Soil Biology & Biochemistry, 218, p.110150_1 - 110150_12, 2026/07
Times Cited Count：0 Percentile：0.00(Soil Science)The role of minerals in soil carbon sequestration has been increasingly recognized. However, the mechanism by which mineral-associated organic matter (MAOM) resists microbial decomposition remains an open question. We prepared MAOM on amorphous allophane and crystalline kaolinite with different organic matter (OM) proxies, characterized the affinity strength of these associations using isothermal titration calorimetry and X-ray photoelectron spectroscopy, and quantified their microbial mineralization through aerobic incubation. We found that amorphous allophane displayed greater OM adsorption capacity due to its higher specific surface area; in contrast, crystalline kaolinite exhibited stronger binding with OM, consistent with its predominant inner-sphere complexation. Furthermore, lower MAOM mineralization was found corresponding to higher Langmuir affinity. This inverse relationship was more pronounced than the correlation with the amount of OM adsorbed by minerals. These findings suggest that the overall MAOM stability is controlled by a balance between binding strength and adsorption capacity. Namely, stronger binding affinity enhances microbial resistance of MAOM, while the abundance of mineral sites determines the amount of MAOM accessible for microbial decomposition. This study presents a novel mechanistic understanding of the MAOM dynamics and refines the prevailing perspective on MAOM persistence.
Taniguchi, Yoshinori; Luu, V. N.; Tasaki, Yudai; Udagawa, Yutaka; Katsuyama, Jinya
Annals of Nuclear Energy, 231, p.112177_1 - 112177_16, 2026/06
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Luu, V. N.; Taniguchi, Yoshinori; Udagawa, Yutaka; Tasaki, Yudai; Katsuyama, Jinya
Annals of Nuclear Energy, 230, p.112114_1 - 112114_14, 2026/06
Times Cited Count：1 Percentile：94.63(Nuclear Science & Technology)Nguyen, H. H.
Annals of Nuclear Energy, 230, p.112171_1 - 112171_13, 2026/06
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)This study examined the effects of the moderator-to-fuel volume ratio, fuel debris shape, and the number of damaged fuel assemblies on the neutronic characteristics of a partially damaged reactor model, where the fuel assemblies at the core center melt to fuel debris while the fuel assemblies at the outer region remain intact. The investigations were conducted using the Serpent code and the JENDL-5 library. The results show that when fuel debris is surrounded by intact fuel assemblies, the k
can be classified into two groups based on the shape of the fuel debris. Conversely, in scenarios where the fuel debris is not fully encircled by intact fuel assemblies, the shape of the fuel debris has a negligible impact on the k. Additionally, the relationship between the number of neutrons entering and leaving the fuel debris determines how the shape of the fuel debris affects the k.
Soma, Yasutaka; Komatsu, Atsushi; Igarashi, Takahiro
Corrosion Science, 265, p.113182_1 - 113182_13, 2026/06
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Takai, Shizuka; Sanga, Tomoji*; Shimada, Taro; Takeda, Seiji
Earth Surface Dynamics, 14(3), p.417 - 432, 2026/06
Understanding river incision model is crucial for predicting long-term landscape evolution. For the bedrock channel incision model (detachment-limited (DL) model: erosion rate 
where 
is drainage area, 
is channel gradient), parameters (
, 
, and 
), can be estimated via slope-area analysis if 
is known. Using 
Be denudation rate, previous studies globally compiled the parameter values for variable lithology. However, limited data availability for soft sedimentary rock restricts the applicability of global compilation. In addition, measuring the Be concentration in sedimentary rock is challenging in humid and tectonically active regions. To address this, slope-area analysis was conducted in the Kamikita Coastal Plain, Japan, where lithology (Miocene to Pleistocene sedimentary rocks) and uplift rate (
0.2 mm y
for the past 300 ka) are assumed to be uniform. River incision rates were derived approximately from widely distributed marine terraces (MIS 5e-11). For six target rivers, DL-like behaviour was confirmed in the limited areas located upstream of the alluvium distribution. The reference concavity 
was 0.44 
0.10, typical for steady-state channels. Across the range of 0.4-0.6, the exponent consistently exhibited nonlinearity ranging between 1.14 to 1.34, which is consistent with the previous global compilations. This observed nonlinearity likely reflects transient landscape responses to past sea-level changes, which generated slope-break knickpoints at similar elevations. Finally, the estimated erosion coefficient (10
-10
) agreed with the global relationship with unconfined compressive strength 
(
), supporting the significant influences of bedrock lithology on .
Segawa, Mariko; Nishinaka, Ichiro*; Maeda, Makoto; Toh, Yosuke
Isotope News, (805), p.7 - 10, 2026/06
no abstracts in English
Sakuma, Kazuyuki; Yoshimura, Kazuya
Journal of Environmental Radioactivity, 297, p.108055_1 - 108055_4, 2026/06
Tritium (
H) is the principal radionuclide remaining in ALPS-treated water discharged from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), and its potential environmental impact has drawn considerable attention. To evaluate possible terrestrial effects, H concentrations were monitored in precipitation, groundwater, and river water in the upper Ota River catchment in Fukushima Prefecture. Monthly samples were collected before and after the initiation of oceanic discharge in August 2023. Time-series comparison showed no discernible increase in H concentrations after the start of discharge for any water type. Non-parametric statistical analysis further confirmed the absence of significant differences for groundwater and river water. Observed variations were consistent with natural background levels and known seasonal patterns in precipitation in Japan. These results indicate that ALPS-treated water discharge has had no detectable impact on terrestrial waters in the study area.
Miyazaki, Kanako*; Fueda, Kazuki*; Kadowaki, Masanao; Terada, Hiroaki; Kozai, Naofumi; Iwata, Hajime; Horie, Kenji*; Takehara, Mami*; Yamasaki, Shinya*; Grambow, B.*; et al.
Journal of Hazardous Materials, 511, p.142180_1 - 142180_17, 2026/06
Times Cited Count：0