Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
堀口 直樹; 吉田 啓之; 山村 聡太*; 藤原 広太*; 金子 暁子*; 阿部 豊*
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 14 Pages, 2022/03
In severe accidents of nuclear reactors, molten fuel and structural materials leak out of the pressure vessel into the water pool on the pedestal floor. If the water pool is shallow, the molten material enters the shallow pool as a liquid jet, disperses as debris, spreads over the floor, and it cooled by fuel-coolant interaction (FCI). Numerical simulations and experiments with state-of-the-art visualization techniques are developed and used to consider the thermal-hydraulic behavior of the liquid jet as a debris jet. By performing these simulations and experiments, we obtain detailed 3-dimensional shapes of the liquid jet interfaces. However, to evaluate the thermal-hydraulic behavior of the liquid jet, we require not only 3-dimensional shapes but also the velocity and size of dispersed liquid. We have developed a dispersed phase tracking method by using time-series data of 3-dimensional shapes of the melt interface obtained by numerical simulations or experiments to obtain these data. Firstly, we verified the applicability of the developed method by applying a simple system. Next, we applied the method to the numerical results of a liquid jet entering a shallow pool by TPFIT. The results show that the liquid jet entering the shallow pool reproduces the dispersion behavior of the fragments. The generated fragments were quantitively confirmed to have curved and rotational trajectories with complex nonlinear motions. In the relationship between the volume equivalent diameter of the fragments and the magnitude of velocity, it was confirmed that the larger the equivalent diameter, the smaller the velocity fluctuation.
外池 幸太郎; 山本 俊弘; 渡辺 庄一; 三好 慶典
Journal of Nuclear Science and Technology, 41(2), p.177 - 182, 2004/02
被引用回数:14 パーセンタイル:66.01(Nuclear Science & Technology)未臨界度監視システムの開発の一環として、検出器信号を時系列データとして収録する機能とファインマン・アルファ法によりアルファ値を評価する機能を一つのシステムとして構築し、STACYの非均質体系の動特性パラメータ(アルファ値)の測定を行った。本システムには橋本の階差フィルターが組み込まれており、臨界状態における測定も可能である。本システムによる測定結果はパルス中性子法による測定と一致した。