This is an awesome read, and likely correct in the narrative, but the cubes they have at hand to study have a bit of a provenance problem - how do we know they were the ones used for the German research?

At any rate, getting a reactor running still was a long way from the industrial capacity the Americans used to get a working device. Industrial capacity Germany just didn't have late in the war. And after Afrika Korps' defeat, they weren't getting any easily accessible materials anymore.