In the final stages of World War II, Nazi scientists had tried to build a nuclear reactor, the B-VIII, in Berlin yet eventually relocated to the small town of Haigerloch to continue the project.
As many as 664 uranium cubes, each measuring two inches on all sides like the one received by Koeth, were strung together like a chandelier. The uranium cubes were placed at the core of the B-VIII reactor and were surrounded by metal-encased graphite shell. The shell itself was located inside a concrete-lined water tank.
If the chandelier reactor was hung in heavy water, the water would act as a regulator for the nuclear reaction. But the project stalled due to a shortage of uranium for the reactor.
Among the German scientists who famously worked on the reactor was Werner Heisenberg, the theoretical physicist who is also credited with the development of the field of quantum mechanics. The Allied forces captured Heisenberg in 1945, while the nuclear reactor — or what had been built of it — was dismantled by U.S. troops at the end of the war.
The 664 cubes of uranium, so the story goes, were shipped to unknown locations in America.
According to Science News, the researchers looked through archival documents from the National Archives in College Park and found references to another 400 or so cubes that existed, yet were held by a different German research group. The scientists concluded that had the different groups combined forces, Germany would have had enough uranium to make a reactor.
As for the fate of the extra 400 cubes, they went onto the black market after the war with many of their locations lost to time.