  We present the newly obtained results of two computer simulations of the
epithermal neutron-nuclear burning in natural uranium. Each of them modeled the
period of six months of the traveling wave reactor (TWR) operation -- for two
different flux densities of an external neutron source. The simulation results
confirm the existence of a nuclear burning wave at longer time scales, and
reveal the dependence of the wave burning modes on the parameters of an
external neutron source.
