Mcnp5 Theory Manual ^hot^

Section 2.10 (Fission Neutron Production). TOTNU uses total (prompt + delayed) neutrons per fission; NONU is non-fission mode. For steady-state reactors, you want TOTNU . For pulse reactors, you need PHYS:N cards.

See Section 5.7, "Tally Energy Balance." Because of non-analog techniques (weight windows), the statistical estimates of heating (F6) and flux (F4) are independent, and their ratio does not necessarily equal the cross-section. This is normal. mcnp5 theory manual

However, the MCNP5 (Monte Carlo N-Particle version 5) code is a black box without its manual. While the user manual tells you how to format an input file, the tells you why a particle behaves a certain way, how the code tallies uncertainty, and what approximations are being made under the hood. Section 2