Subcritical water treatment of spent tannin-based uranium recovery adsorbent

Iwamoto, Toshihiro; Omori, Kohei; Arai, Yoichi; Funakoshi, Tomomasa; Watanabe, So; Nakamura, Masahiro; Watanabe, Masaru*

Proceedings of 32nd International Conference on Nuclear Engineering, Vol.13 (Internet), p.525 - 533, 2026/01

https://doi.org/10.1007/978-981-95-3409-8_44

Development of validation matrix of fuel assembly thermal-hydraulics sub-channel analysis code for sodium-cooled fast reactors

Kikuchi, Norihiro; Yoshikawa, Ryuji; Tanaka, Masaaki

Proceedings of 32nd International Conference on Nuclear Engineering, Vol.15 (Internet), p.647 - 659, 2026/01

https://doi.org/10.1007/978-981-95-3417-3_53

An in-house subchannel analysis code called ASFRE have been developed to evaluate fuel assembly (FA) thermal-hydraulics in sodium-cooled fast reactors (SFRs). In this study, models to solve the important phenomena in the FA and necessary experiments for validation were listed systematically in order to assess the reliability of the codes, through developing an importance ranking table for the phenomena and a validation matrix according to the guide-line for the verification and validation (V&V). The ranking table was developed to decide the priority for validation. In addition, a validation matrix of experimental data and numerical models in the codes for the high priority phenomena in the ranking table were developed to confirm the sufficiency of the validation process.

Machine learning techniques for the development of an , and radiation sources discrimination software using a 2d-imaging radiation detector

Laffolley, H.; Tsubota, Yoichi; Tsuji, Tomoya; Honda, Fumiya; Nitta, Ayako; Kikuchi, Riku

no journal, , 

In support of the decommissioning efforts at the Fukushima Daiichi Nuclear Power Station, the Japan Atomic Energy Agency (JAEA) is developing the TRACE software for the accurate discrimination of alpha, beta, and gamma radiation sources in radioactive samples. This new technology utilizes the MiniPIX, a commercial 2D imaging semiconductor radiation sensor. The MiniPIX provides both a spatial image of radiation interactions within its pixel matrix and quantification of the energy transferred. The TRACE software analyzes the data from the MiniPIX by examining the energy and shape of pixel clusters created by radiation events. It identifies alpha particles primarily through the higher energy transferred in their interactions. For other events, it extracts shape parameters: gamma particles, having a quasi-straight path, create very small pixel clusters, while beta particles, being more deviated, generate snake-like clusters. The software can also provide an energy spectrum split by radiation type to assist in identifying radioisotopes. A core component of TRACE is a machine learning algorithm, trained using data acquired from standard sources such as Cobalt-60, Strontium-90, Cesium-137, and Americium-241, chosen for their relevance to Fukushima samples. Planned future integration with an XYZ motorized stage aims to automate data acquisition, improve efficiency, facilitate handling of radioactive and non-flat samples, and enable real-time adjustment of acquisition duration.

Evaluation of gas entrainment flow rate by circulating annular flow model

Ito, Kei*; Odaira, Naoya*; Ito, Daisuke*; Saito, Yasushi*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki

no journal, , 

Various studies are conducted to predict the onset condition of gas entrainment by a free surface vortex in sodium-cooled fast reactors. However, there are few studies on the estimation of entrained gas flow rate. The authors have proposed a candidate evaluation model of gas flow rate based on circulating annular flow model. In this study, to confirm the applicability of the model to actual reactors, entrained gas flow rate is evaluated using the liquid velocity distribution around free surface dent of vortex (gas core), obtained by CFD data. As a result, the evaluated entrained gas flow rate shows smaller value to the measurement data, which implying the interfacial friction coefficient employed in the circulating annular is optimized for flow in suction pipe and not suitable for flow around a gas core. Then, the parameter survey on the interfacial friction coefficient is performed to find an appropriate value for a realistic evaluation of entrained gas flow rate in actual reactors.