The radioactivity from neutron activation is overplayed a bit. Its quite manageable if you keep the shot count low. Even without careful materials choices. The real problem is the amount of shielding you need for the neutrons in the first place. Its really quite a bit if you expect +1J of neutrons in a shot. I have though that water tanks with borated water etc would be a good temporary way of dealing with neutrons. Added advantage of reducing activation since the Boron absorbs most of the neutrons.
