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永武 拓; Jiao, L.; 上澤 伸一郎; 高瀬 和之; 吉田 啓之
no journal, ,
In the 2011 Fukushima Daiichi nuclear disaster, seawater was injected into the reactors to cool down the nuclear fuels. The seawater provided a potential to affect the heat transfer due to the changes of the physical properties of the coolant. Therefore, in this study, measurement of the basic thermal-hydraulic data of the salt solutions was performed. The experimental parameters adopted in this study were the salinity, Reynolds number, the mass flux, the inlet temperature and the heat flux of the inner wall. In the experiment, the salinity effect on the heat transfer ability and the hydraulic characters were observed. In a non-dimensional analysis of the single phase cases at high mass flux, all of the measured cases can be predicted well by the Sider-Tate correlation, no obvious changes of the heating ability was found. Hence, in single phase cases without boiling, it is thought that salt solution owns similar heat transfer ability of water except the influence of the fluid property difference.
永瀬 文久; 吉田 啓之; 加治 芳行; 天谷 政樹
no journal, ,
福島第一原子力発電所の廃止措置を適切かつ確実に行うためには、事故進展と炉内状況の推定の精度を高める必要がある。このことは、シビアアクシデント防止及び緩和に関する既存炉の安全対策の有効性を確認するためにも、さらに我が国が事故事象を高精度で再現する予測手法を準備するためにも重要である。このため原子力機構は、BWRにおける炉内熱水力挙動、燃料損傷及び崩落過程、構造材及び圧力容器挙動、事故解析、下部支持板と下部ヘッド間の下部プレナムにおける溶融物移動などに関する研究及び開発を実施している。本報告では、主な研究の進捗及び成果について述べる。
Mascari, F.*; 中村 秀夫; De Rosa, F.*; D'Auria, F.*
no journal, ,
In the development and safety evaluation of LWRs, thermal hydraulic analysis of the reactor, containment and their coupling is essential to understand the accident phenomena. To reproduce the behavior in a scaled model, it is necessary to properly characterize thermal hydraulics both in the local and integral responses. The facility geometry and test conditions should then be correctly derived according to scaling laws to avoid scaling distortions that could compromise the target phenomena identified by PIRT process. Many scaling approach and methods have thus been developed. Together with the scaling analysis, computer codes may be used in supporting the design of test facilities, assessing the scale distortions, and verifying the selected scaling method. However, since the closure laws in the computer code are mainly based on scaled test data, the extrapolation of code results remains a challenging and open issue. This paper provides some insights about the methods used in the scaling.