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Ono, Ayako; Sakashita, Hiroto*; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki
Mechanical Engineering Journal (Internet), 11(4), p.24-00188_1 - 24-00188_12, 2024/07
Japan Atomic Energy Agency (JAEA) is developing the evaluation method for a two-phase flow in the reactor core using simulation codes based on the Volume Of Fluid (VOF) method. JAEA started developing a Simplified Boiling Model (SBM) for the large-scale two-phase flow in the fuel assemblies. In the SBM, the motion and growth equations of the bubble are solved to obtain their diameter and time length at the detachment, of which size scale is within/around the calculation grid size of the numerical simulation. JUPITER calculates the bubble behavior with a scale of more than several 
m. In this study, the convection boiling on a vertical heating surface is simulated using the developed SBM. The comparison between the simulation and experimental results showed good reproducibility of the heat flux and velocity dependency on the passage period of the bubble.
Ono, Ayako; Yamashita, Susumu; Sakashita, Hiroto*; Suzuki, Takayuki*; Yoshida, Hiroyuki
Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-13) (Internet), 12 Pages, 2022/09
Japan Atomic Energy Agency is developing the computational fluid dynamics code, JUPITER, based on the volume of fluid (VOF) method to analyze detailed thermal-hydraulics in a reactor. The detailed numerical simulation of boiling from a heating surface needs a substantial computational cost to resolve the microscale thermal-hydraulic phenomena such as the bubble generation from a cavity and evaporation of a micro-layer. This study developed the simplified boiling model from the heating surface to reduce the computational cost, which will apply to the detailed simulation code based on the surface tracking method such as JUPITER. We applied the simplified boiling model to JUPITER, and compared the simulation results with the experimental data of the vertical heating surface in the forced convection. We confirmed the degree of their reproducibility, and the issues to be modified were extracted.
Onuki, Akira; ; Iguchi, Tadashi; Murao, Yoshio
JAERI-Research 94-012, 59 Pages, 1994/08
JAERI-Research-94-012.pdf:1.75MB
no abstracts in English
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Nihon Genshiryoku Gakkai-Shi, 18(12), p.786 - 795, 1976/12
Times Cited Count：1no abstracts in English
-ray beamsSeya, Michio; Hajima, Ryoichi*; Hayakawa, Takehito*; Koizumi, Mitsuo
no journal, ,
The NRF-base NDA using monochromatic -rays would be used in nuclear security for secure detection of NM in thick shield and also for precise checking of interior structures of detected / suspicious objects. This NDA also would be used in nuclear safeguards for precise quantification of U/Pu isotopes in high radiation background, such as spent fuel assemblies / melted fuel debris in a canister. It is also useful for precise measurement of quantities of minor actinide isotopes in ADS (Accelerator Driven Sub-critical System; for transmutation of long-half-life minor actinides (MA)) fuels before and after irradiation in the ADS reactor core. In this presentation, we show actual NRF-NDA methods for these objects.
