Nazi nukesHow close was Nazi Germany to the bomb?

Published 20 June 2019

How close did Nazi Germany get to a working nuclear reactor? Researchers exploring the German quest and failure to build a working nuclear reactor during the Second World War say that Germany was close – but that the effort was hampered by decentralization and lack of scientific communication. “If the Germans had pooled their resources, rather than keeping them divided among separate, rival experiments, they may have been able to build a working nuclear reactor,” says an expert.

Back in 2013, Timothy Koeth, an associate research professor at the University of Maryland, received a rather extraordinary birthday gift: a little cloth lunch pouch containing a small object wrapped in brown paper towels. As Koeth peeled back the layers, his eyes grew wide with astonishment. He immediately asked, “Where did you get that?”

Inside he found a heavy metal cube and a crumpled message, a provocative note wrapped around a stone that came crashing through the window of history. It read, “Taken from Germany, from the nuclear reactor Hitler tried to build. Gift of Ninninger.”

Koeth’s friend grinned, picked up the 5-pound block of uranium metal and handed it to him. Though modest in size, the cube was heavy, dense and steeped in lost history. Koeth accepted the cube and its note as an invitation to the adventure of a lifetime.

In the May 2019 issue of Physics Today, Koeth and Miriam Hiebert, a doctoral candidate working with him on this project at UMD’s A. James Clark School of Engineering, describe what they’ve discovered while exploring the German quest and failure to build a working nuclear reactor during the Second World War.

Uranium is weakly radioactive, and this particular cube measures about 2 inches on each side. “It’s surprisingly heavy, given its size, and it’s always a lot of fun to watch people’s reaction when they pick it up for the first time,” said Hiebert.

A chandelier of nuclear elements
AIP notes that this cube represents one of 664 uranium metal components that were strung together in a form reminiscent of a chandelier to comprise the core of a nuclear reactor experiment that a team of German scientists attempted to build toward the end of the World War II, including Werner Heisenberg — a theoretical physicist and one of the key visionaries of quantum mechanics. The chandelier was submerged in heavy water to regulate the rate of fission.