On pulsed reactor power oscillations and stability limit

The reactivity-power relations in the case of reactivity periodic oscillations in a pulsed reactor are derived with reactivity temperature effect taken into consideration. The results show amplification of oscillations by the negative temperature coefficient, if the oscillation frequency is 0.25-0.50 of the reactor power pulse frequency. When the nondimensional parameter of a feedback is -1, the amplification goes to infinity, i.e. a reactor became unstable (in linear approximation). The analysis of ''free'' oscillations of a reactor power when the reactor is linearly unstable is given also. The limit of power nonstability for the IBR-2 reactor is estimated to be equal to 10 MW; that limit for pulsed reactors with selfquenching of power pulses is much lower (about two-order of magnitude)