Dependence of propagation phenomena on the reactivity of a subcritical assembly

The propagation of thermal neutron pulses in the graphite region between the two cores of a Double-Core Reactor was studied. By locating neutron detectors along the line of propagation, a dependence has been noted of the time interval Δt_max, separating the time locations of the peaks of a pulse propagating from the one core to the other, on the reactivity of the two-core system. The observed phenomenon may be related with a dependence of the "lag time", a parameter of interest in the kinetics of a symmetrical two-core system, on its reactivity.