> even if he had a startup neutron source In the words of my [nuclear engineering] professor: "criticality is a property of the system and is independent of an

> even if he had a startup neutron source In the words of my [nuclear engineering] professor: "criticality is a property of the system and is independent of any external source." 1kg of uranium isn't enough to form a critical mass, period. Nothing else really matters and adding a source doesn't change that. It's possible this person built something that experienced induced fissions, but a self-sustaining chain reaction (i.e., a reactor) is not.