AbstractA series of static critical experiments has been performed on an accurate mockup of the SORA Reactor. SORA is a proposed NaK cooled, repetitively pulsed fast reactor which would be used as a high-intensity neutron source for time-of-flight experiments. The reactivity of this reactor is varied by a movable reflector. Those parameters which are related to the kinetics of the reactor have been investigated thoroughly in the critical experiments. They have been measured for both beryllium and iron reflectors of several sizes and for various core and fixed reflector configurations.The total reactivity of the movable reflectors varied from $3.7 for a 11.0-cm-wide iron reflector to $12 for a 26.2-cm-wide beryllium reflector. The reactivity of the movable reflector as a function of its position has been shown to have a parabolic dependence on position characterized by the parameterαx, which varied from 4 to 9.9¢/cm2. The prompt-neutron time decay is described by a fast decay constant which varied between 0.30 and 0.55/µsec and a slow decay constant which varied between 0.05 and 0.10/µsec. The critical mass for the various experiments was between 50.3 and 57.3 kg of uranium enriched to 93.2 wt%235U. Using space-independent neutron kinetics with one delayed-neutron group, it has been shown that with a 24-cm-high×7-cm-thick×21-cm-wide beryllium reflector the assembly will produce 100 pulses/sec∼50-µsec wide at half-maximum power with a peak-to-average power ratio of∼180.