Oscillations in the Power Distribution within a Reactor1

In a reactor of sufficient size and operating at sufficiently high power density, an oscillation in the spatial distribution of power may arise because of interplay between the effect of Xe¹³⁵ on flux distribution and the fact that its appearance after fission is delayed by the decay time of I¹³⁵. By use of a very simple reactor model the conditions required to establish such an instability are studied; amplitude and frequency characteristics of the oscillation are also investigated.