Methods of xenon stability analysis in nuclear reactors

Abstract

The subject of this study is the constsuction of some sufficiernt conditions for Xenon stability in therinal reactors during operation, and the approximate time behaviour of the point kinetics system with feedback. The same topic had been investigated by J, Chernick, G. Lellouche and W. Wollmann[7] in 1961. It had been shown that Xenon instability remains a serious concern in the preseace of temperature damping. Later A. Z. Akpasu and P. Akhtar studied the problem in 1966 [2]. They approached the problem as one of asymptotic stability in the large for point reactors with non-linear feedback; and gave a new criterion for boundedaess of Xenon oscillations in the presence of temperature feedback, In the first three chapters basic kinetic equations are derived for the point reactor model, mainly to emphasize the extent of careful work required to obtain the mean neutron generation time. Then global stability analysis of Xenon is examined and the region of asymptotic stability in the large in the plane of equilibrium flux vs, temperature coeffioient is determined. In chapter four linear stability analysis is considered a d conditions for linear stability are determined with and without delayed neutrons; and the results axe compared. In constructing the stability conditions, various approximations arid combinations of parameters were utilized, Further, point kinetics equations are solved for certain reactor operating conditions and the time behaviour of the flux is observed in order to assess some properties such as period and amplitude of oscillations in the region of stability and instability. The results are compared with that of other workers in the field[2]. Results, plots and the discussions are given in the last chapler. Computer programs used in this work are also provided in the appendices.