As dctoedt pointed out it appears that I might be wrong in this case, I had assumed that the fallout was producing significant neutron radiation which interacte

As dctoedt pointed out it appears that I might be wrong in this case, I had assumed that the fallout was producing significant neutron radiation which interacted with its surroundings to produce greater amounts of radiation. Adding a moderator in that circumstance should have reduced the burden a bit in theory.