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Yoshida, Kazuo; Hiyama, Mina*; Tamaki, Hitoshi
JAEA-Research 2025-003, 24 Pages, 2025/06
JAEA-Research-2025-003.pdf:2.06MB
An accident of evaporation to dryness by boiling of high-level radioactive liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (RuO
) are released from the tanks with water and nitric-acid mixed vapor into the atmosphere. Accurate quantitative estimation of released Ru is one of the important issues for risk assessment of those facilities. RuO is expected to be absorbed chemically into water dissolving nitrous acid. Condensation of mixed vapor plays an important role for Ru transporting behavior in the facility building. The thermal-hydraulic behavior in the facility building is simulated with MELCOR code. The latent heat, which is a governing factor for vapor condensing behavior, has almost same value for nitric acid and water at the temperature range under 120 centigrade. Considering this thermal characteristic, it is assumed that the amount of nitric acid is substituted with mole-equivalent water in MELCOR simulation. Compensating modeling induced deviation by this assumption have been assembled with control function features of MELCOR. The comparison results have been described conducted between original simulation and modified simulation with compensating model in this report. It has been revealed that the total amount of pool water in the facility was as same as both simulations.
Shiina, Yasuaki; Inagaki, Terumi*
International Journal of Heat and Mass Transfer, 48(2), p.373 - 383, 2005/01
Times Cited Count：37 Percentile：73.11(Thermodynamics)Improvement of thermal conductivity of phase change medium would be one of the effective techniques to reduce phase change time in latent heat storage technology. Thermal conductivity would be improved by saturating phase change materials (PCM) in porous metals. Efficiency of effective thermal conductivity on melting time is studied by analyzing melting characteristics of a heat storage circular capsule where porous metal saturated by PCM is inserted. Results show that considerable reduction in melting time was obtained, especially for low conductivity PCMs and for high heat transfer coefficient. Trial estimation of optimum porosity was presented under the conditions of keeping high latent heat capacity and high reduction rate of melting time. Optimum porosity decreases with increase in heat transfer coefficient.
Kurihara, Ryoichi
Fusion Engineering and Design, 61-62, p.209 - 216, 2002/11
Times Cited Count：4 Percentile：28.08(Nuclear Science & Technology)To attain high fusion power density, the divertor must suffer high heat flux from the fusion plasma. It is very difficult to remove a high heat flux more than 20 MW/m
using the only solid divertor plate from the viewpoint of severe mechanical state such as thermal stress and crack growth. Therefore, a concept of liquid divertor is proposed to remove high heat flux by liquid films flowing on a solid wall. This paper mainly descries a preliminary thermofluid analysis of the free surface liquid flow, made of the FliBe molten salt, using the finite element analysis code ADINA-F. The heat flux of 25
100 MW/m was given on the free surface liquid of the flow. I explored a possibility of applying the secondary flow to enhance the heat transfer of the liquid flow suffering high heat flux. This analysis shows that the heat flux of 100 MW/m can be removed by inducing the secondary flow in the free surface liquid FLiBe. And this paper shows that the liquid divertor using solid-liquid multi-phase flow makes possible large heat removal by utilizing the latent heat of fusion of solid phase.
E.Choi*; Akino, Norio
Proc. of 11th Int. Heat Transfer Conf. (Heat Transfer 1998), 7, p.121 - 126, 1998/00
no abstracts in English
Akino, Norio
Dai-13-Kai Nihon Netsu Bussei Shimpojiumu Koen Rombunshu, p.273 - 276, 1992/00
no abstracts in English
