A Study on the applicability of uncertainty quantification and sensitivity analysis in validation process for fast reactor plant dynamics analysis code

Hamase, Erina; Kawamura, Takumi*; Doda, Norihiro; Tanaka, Masaaki

Annals of Nuclear Energy, 236, p.112358_1 - 112358_13, 2026/10

https://doi.org/10.1016/j.anucene.2026.112358

To 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.

Nanoplastics reprogram fungal metabolism to reshape extracellular microenvironments and manganese biomineralization

Wu, C.*; Qiu, X.*; Tanaka, Kazuya; Tani, Yukinori*; Lloyd, J. R.*; Yu, Q.*

Bioresource Technology, 456, p.134916_1 - 134916_9, 2026/09

https://doi.org/10.1016/j.biortech.2026.134916

no abstracts in English

Evaluation of deuteron nuclear data on iron isotopes

Nakayama, Shinsuke

Fusion Engineering and Design, 230, p.115866_1 - 115866_6, 2026/09

https://doi.org/10.1016/j.fusengdes.2026.115866

In fusion reactors beyond the experimental reactor stage, reactor materials are exposed to a large flux of high-energy neutrons. The International Fusion Materials Irradiation Facility (IFMIF) is a material irradiation testing facility that utilizes an accelerator-based neutron source to assess the integrity of such reactor materials. In IFMIF, neutrons are generated by irradiating a liquid lithium target with a 40 MeV deuteron beam. For evaluating radioactivity production and designing radiation shielding in IFMIF and various precursor facilities, nuclear data on deuteron-induced reactions for iron, a primary structural material of accelerators, are required. These data include the production cross-sections of radioactive isotopes such as Mn-54, Co-56, and Co-57, as well as the energy and angular distributions of emitted neutrons. However, high-precision deuteron nuclear data for iron isotopes have not been available until now. We have previously evaluated and compiled deuteron nuclear data for light nuclei (Li-6,7, Be-9, C-12,13) for neutron source design and released them as JENDL/DEU-2020. Subsequently, we incorporated data for Al-27, Cu-63,65, and Nb-93 into the above data and published it as the deuteron sublibrary of the Japanese general-purpose nuclear reaction library JENDL-5. In this study, we evaluated deuteron nuclear data for the stable isotopes of iron (Fe-54,56,57,58). The evaluation was conducted using DEURACS, a nuclear reaction calculation code specifically designed for deuteron-induced ones, as in our previous work. As a result, the evaluated data successfully reproduced not only the residual nucleus production cross-sections but also the neutron emission spectra. In this presentation, we will provide an overview of the evaluation methodology and discuss the obtained results.

Measuring the velocity of fragments produced by high-repetition-rate nanosecond laser pulses; A Technique to visualize the fragments for laser decontamination

Kosuge, Atsushi; Ando, Kota*; Yamamoto, Keisuke*; Nakajima, Takashi*

Optics & Laser Technology, 201, p.115269_1 - 115269_6, 2026/09

https://doi.org/10.1016/j.optlastec.2026.115269

Probabilistic fracture mechanics benchmarking study of PASCAL-SP code with xLPR code regarding primary water stress corrosion cracking

Mano, Akihiro; Yamaguchi, Yoshihito; Katsuyama, Jinya

International Journal of Pressure Vessels and Piping, 222, p.105792_1 - 105792_11, 2026/08

https://doi.org/10.1016/j.ijpvp.2026.105792

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.

Applicability of instrumented indentation for assessing allowable flaw sizes of circumferentially flawed stainless steel piping

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

https://doi.org/10.1115/1.4071687

Real-time inversion of radioactive source distribution using air dose rate measurements via least absolute shrinkage and selection operator method

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

http://doi.org/10.1016/j.ress.2026.112538

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.

Prediction of tumor control probability in prostate cancer radiotherapy using a biophysical model incorporating cancer stem cell and hypoxia

Saga, Ryo*; Iwamori, Kenta*; Matsuya, Yusuke; Hosokawa, Yoichiro*

Computers in Biology and Medicine, 211, p.111743_1 - 111743_10, 2026/07

https://doi.org/10.1016/j.compbiomed.2026.111743

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.

NMR evidence for full-gap spin-triplet superconducting state in UBe

Minami, Shoko*; Matsuno, Haruki*; Morita, Kyohei*; Matsuki, Rintaro*; Kotegawa, Hisashi*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Tou, Hideki*

Journal of the Physical Society of Japan, 95(7), p.074711_1 - 074711_11, 2026/07

https://doi.org/10.7566/JPSJ.95.074711

Experimental evaluation of high-temperature fuel-coolant thermal interaction behavior using unirradiated fuel powder

Mihara, Takeshi; Urano, Kenta; Udagawa, Yutaka; Kakiuchi, Kazuo

JAEA-Technology 2026-009, 15 Pages, 2026/06

JAEA-Technology-2026-009.pdf:1.15MB

Mechanical energy generated during fuel failure under reactivity-initiated accident (RIA) conditions, such as pressure pulse and water hammer, strongly depends on the fragmentation state and temperature of the fuel. When failure caused by pellet/cladding mechanical interaction (PCMI) occurs rapidly at low temperature, fission gas release drives pellet fragments to move at high velocity in water, leading to extremely efficient heat transfer between the fuel and coolant. This results in rapid vapor generation and the production of impulsive mechanical energy. These observations indicate that both the particle surface area and the highly efficient heat transfer associated with high-velocity fragment motion are key influencing factors. In the 264-2 and 264-24 experiments, test conditions were designed to simulate fuel-coolant interaction under conditions where the driving force for pellet fragment motion, which is characteristic of RIA events, is absent. In the 264-24 test, the specific surface area of the pellet particles (surface area per unit mass) was designed to exceed that of previously tested high-burnup fuels. In addition, the fuel enthalpy (thermal energy per unit mass) was set based on prior observations to conditions where significant mechanical energy generation is expected. As a result, both the pressure pulse and water hammer energies were significantly lower than those observed in high-burnup fuel failure cases, where the driving force for pellet fragment motion is considered to be present. This clearly demonstrates the critical importance of the driving force for pellet fragment motion in the generation of mechanical energy.