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上澤 伸一郎; 永武 拓; Jiao, L.; Liu, W.; 高瀬 和之; 吉田 啓之
Proceedings of International Conference on Power Engineering 2015 (ICOPE 2015) (CD-ROM), 11 Pages, 2015/11
To understand the current status of the TEPCO's Fukushima Daiichi Nuclear Power Station, the progress of the accident has been calculated by severe accident analysis codes, for example, MAAP, SAMPSON and so on. However, effects of seawater are not considered in these calculations, although the seawater was attempted to inject into the reactors to cool down the nuclear fuels. In the present study, the objective is to understand the basic physical effect of the seawater on the thermal-hydraulic behavior without boiling. We measured and compared the thermal-hydraulic behavior in pure water, NaCl solution and artificial seawater with the concentration of 3.5wt% in a heat transfer and flow visualization experiment by using an internally heated annulus. Above Re = 2300 [-], the correlations between Nusselt number and Reynolds number in the NaCl solution and the artificial seawater were the same with that in the pure water. Moreover, the correlation can be predicted by Dittus-Boelter equation. Below Re = 2300 [-], the Nusselt numbers of each fluid correlated with the Rayleigh number. Therefore, considering physical properties of the NaCl solution and the artificial seawater, the thermal-hydraulics behavior without boiling in the NaCl solution and the artificial seawater was not different from the behavior in the pure water.
吉田 啓之; 上澤 伸一郎; 永武 拓; Jiao, L.; Liu, W.; 高瀬 和之
Proceedings of International Conference on Power Engineering 2015 (ICOPE 2015) (CD-ROM), 9 Pages, 2015/11
In the Fukushima Daiichi Nuclear Power Plant accident, seawater was injected into the reactor to cool down the nuclear fuels. The injection of the seawater may change the thermal-hydraulic characteristics. Therefore, the thermal hydraulic behavior of seawater has to be evaluated to consider the current status of Fukushima Daiiichi Nuclear Power Plants. However, there is little information about the thermal-hydraulic characteristics of seawater. In order to understand the effects of the seawater on the thermal hydraulic behaviors, a research project was started in Japan Atomic Energy Agency. In this research project, we performed two-different type experiments, one is a heat transfer and visualization experiment by using an internally heated annulus, the other is a heat transfer experiment by using a degraded core simulated test section. In this paper, the outline of the research project and examples of results are reported. For single phase flow conditions, heat transfer coefficients of evaluated by the existing correlation and thermal properties of the artificial seawater almost agreed with the experimental results. For two-phase flow conditions, the results of the artificial seawater were different from that of pure water and the NaCl solution. In the artificial seawater, small solid depositions were observed, and it was considered that these solid depositions affected the thermal hydraulic behavior of the artificial seawater.