Estimate of the boundary resonance effects in fast reactors with a steel or nickel reflector

The number of interfaces in the reactor is small but the size of the near-boundary region in which the resonance structure of the neutron spectrum is established is quite large by comparison with the size of the core, and the boundary resonance effect has an appreciable effect on the integral characteristics of the reactor. A calculation was performed for the ZPR-III/54 critical assembly, in which the subgroup approximation was used only for describing the propagation of the neutrons in the iron reflector, the core itself was calculated in group approximation. The value of k/sub eff/.0.981 determined in this case, is in all only (0.5/plus or minus/0.5)% lower than for the full subgroup calculation