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Hamase, Erina; Ohgama, Kazuya; Kawamura, Takumi*; Doda, Norihiro; Yamano, Hidemasa; Tanaka, Masaaki
no journal, ,
Validation of an analysis model for a plant dynamic analysis code named Super-COPD including neutronics calculation of a one-point reactor kinetics model necessitates the further work on the beyond design basis accident. Therefore, JAEA participated in IAEA benchmark for Loss of Flow without Scram (LOFWOS) test No.13 performed at the Fast Flux Test Facility (FFTF), and the transient analysis at the first blind phase considering with major reactivity feedback mechanisms was carried out. It was observed that the whole plant dynamics analysis could follow the measured data. As a future work, the gap conductance model for transient, the upper plenum of reactor vessel with dividing several regions or multi-dimensional modeling, and the core model that can evaluate the radial heat transfer rate more accurately will be refined.
Uchibori, Akihiro; Shiina, Yoshimi*; Watanabe, Akira*; Takata, Takashi*
no journal, ,
A computational fluid dynamics code, SERAPHIM, for sodium-water reaction has been developed. An unstructured mesh-based analysis method was integrated into this code for a complex-shaped domain including multiple heat transfer tubes. In this study, both structured- and unstructured-mesh analyses of the experiment on sodium-water reaction in a tube bundle domain was performed to investigate. The analyses showed that non-physical flow behavior in the case of the coarse structured mesh was improved by the unstructured mesh.
Nagata, Sho*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Igarashi, Takahiro; Miyake, Shugo*
no journal, ,
A spot periodic heating method is a highly accurate, non-contact method for evaluation of anisotropy and relative thermophysical property distribution. However, accurately evaluating thermal diffusivity is difficult due to the influence of temperature wave reflection from the whole surface of the sample. In a previous paper, we proposed a method to derive thermal diffusivity using a parameter table based on heat transfer equations using the concept of optimum distance between of heating-point and measurement point considering the finite sample size, sensitivity distribution of infrared ray detector, intensity distribution of heating laser and sample thickness. In these results, the obtained thermal diffusivity of pure copper was in good agreement with some literature values. However, in the measurement of pure copper with different thicknesses, the temperature response was different from that obtained by the analytical solution. The effect of reflection of temperature waves is significant and needs to be verified by numerical analysis using the finite element method.
Terada, Atsuhiko; Hino, Ryutaro; Nagaishi, Ryuji
no journal, ,
In the storage of water-containing radioactive waste such as fuel debris, it is important to reduce the risk of explosion and combustion due to hydrogen generated to radiolysis of water. In this study, as part of the development of simulation technologies for verification of reduction measures, the hydrogen concentration behavior of the packed bed in the storage container was simulated using CFD code. A trial simulation was conducted and it was found that the hydrogen concentration distribution was affected by the flow path structure of vent pipe.