ANALYSES OF EXPERIMENTAL POWER-REACTIVITY FEEDBACK TRANSFER FUNCTIONS FOR A NATURAL CIRCULATION BOILING WATER REACTOR

ABS>Experimental power-reactivity feedback transfer functions were calculated from the EBWR power transfer function measurements. A simplified model of the EBWR kinetics was developed, using an analog computer, and an analytic expression was obtained for the feedback function. The analytic solution was fitted to the experimental functions to obtain power coefficients and time constants for various modes of operation. These data were extrapolated, and a power transfer function was predicted for 40 Mw. The reactor fumction was measured and compared with the prediction. A stability study was carried out, using open loop transfer functions containing the experimental feedback functions. Extrapolation of the gain and phase margins indicated stability to at least 66 Mw. The reactor was successfully operated at 61.7 Mw following this, with power limited by the capacity of the feedwater pumps. The use of the simplified model for parameter studies is demonstrared by a series of calculations to evaluate the effect of heat transfer time constant on stability. (auth