Theory of Hydraulic Stability of Boiling Channels

Analysis of Structure of Problem

抄録

A framework of boiling channel stability theory is analyzed. The fundamental equations are those of STABLE code : Three conservation laws of mass, energy and momentum applied to one-dimensional channel, together with Bankoff' slip and Marinelli-Nelson's pressure drop correlation. These equations are analyzed to yield "Void Equation", "Linear-ized Void Equation", "Volume Conservation Law" and the "Flow Impedance" R(s), defined by the dynamic response of pressure drop to the inlet flow. The impedance contains all the information such a stability index, dominant frequency and damping ratio. It is shown that R is a sum of the form R_IA + N_F^-1R_D + N_RR_R + N_OR, where N's are non-dimensional parameters and R's characteristic impedances determined by three kinds of parameters, N_X, N_s, and the power distribution parameter. Systematic edition of the characteristic imoedances according to the non-dimensional parameters will reduce the need for case-by-case STABLE calculations. Hydraulic stability of BWR channels under constant system pressure, is a phenomenon with three parameters in view of complexity. Furthermore an analysis is conducted to confirm the above stability structure and three typical instabilities are identified.