Ultraslow wave nuclear burning of uranium–plutonium fissile medium on epithermal neutrons

Highlights: • We study the nuclear burning wave existence in a wide range of neutron energies. • The traveling wave may exist in cold, epithermal and resonance neutrons. • Ultraslow wave in uranium–plutonium media with subcritical enrichments is obtained. • We model the ultraslow wave in natural uranium for epithermal neutron energies. - Abstract: For a fissile medium, originally consisting of uranium-238, the investigation of fulfillment of the wave burning criterion in a wide range of neutron energies is conducted for the first time, and a possibility of wave nuclear burning not only in the region of fast neutrons, but also for cold, epithermal and resonance ones is discovered for the first time. For the first time the results of the investigation of the Feoktistov criterion fulfillment for a fissile medium, originally consisting of uranium-238 dioxide with enrichments 4.38%, 2.00%, 1.00%, 0.71% and 0.50% with respect to uranium-235, in the region of neutron energies 0.015 ∼ 10.00 eV are presented. These results indicate a possibility of ultraslow wave neutron-nuclear burning mode realization in the uranium–plutonium media, originally (before the wave initiation by external neutron source) having enrichments with respect to uranium-235, corresponding to the subcritical state, in the regions of cold, thermal, epithermal and resonance neutrons. In order to validate the conclusions, based on the slow wave neutron-nuclear burning criterion fulfillment depending on the neutron energy, the numerical modeling of ultraslow wave neutron-nuclear burning of a natural uranium in the epithermal region of neutron energies (0.1 ∼ 7.0 eV) was conducted for the first time. The presented simulated results indicate the realization of the ultraslow wave neutron-nuclear burning of the natural uranium for the epithermal neutrons.