We have this modelling of a Frascati Neutron Generator (FNG) irradiation and benchmark case. (This is in preparation for actual measurements.)
There is a neutron source, some LiPb, steel, plastic etc. next to the neutron source, as well as 7 pairs (up+down) of locations for activation measurements at various depths of LiPb b/w the source and the tally location. In each location, there are 10 reactions tallied as well as the neutron flux as a function of energy.
Both codes are using mostly Jeff3.3 cross sections. MCNP uses IRDFF 1.05 for most activation tallies, while Serpent uses Jeff3.3 except for the Nb and In reactions IRDFF-II is used.
The bottom of the post shows the results. One can notice that:
- The neutron flux matches within a couple of % at energies below ~1MeV
- The activation calculations show that Serpent overestimates the activation by 10%-15%, increasingly so while the moving deeper into the material.
- Above ~1MeV Serpent seems to consistently overestimate the flux, more the deeper one is in the material.
- Simppa -