Study on the predictive evaluation method of nonlinear sloshing wave height and load of cylindrical tanks, 4; Study on nonlinear sloshing wave height and flow velocity

Ikesue, Shunichi*; Yamamoto, Tomohiko  ; Miyazaki, Masashi; Tanaka, Masaaki  ; Yokoi, Shinobu*; Sago, Hiromi*; Morita, Hideyuki*

The design basis ground motions have been revised to improve the seismic resistance of nuclear power plants. The reduction of seismic forces not only horizontally but also vertically has required more critical than in the past to ensure the seismic resistance of components. Notably, the design of a Sodium-Cooled Fast Reactor will require reducing the seismic forces applied to the components because of the components with thin wall thickness. To overcome this problem, the authors plan to introduce a seismic isolation system. However, the natural frequency of first order sloshing may be close to the response frequency of the Sodium-Cooled Fast Reactor with the seismic isolation system, and the sloshing wave height is expected to increase. When the sloshing wave height increases, the sloshing becomes the nonlinear sloshing, which can't be evaluated by linear sloshing theory. In order to evaluate the sloshing loads, which act on the roof and the internal structure, the nonlinear sloshing liquid surface shape and the nonlinear sloshing flow velocity are necessary. Therefore, the authors studied the predictive evaluation method of the nonlinear sloshing for the liquid surface shape and the flow velocity with simplified equations. This paper reports on an overview of this predictive evaluation method.