Did Germany really come close to making an atomic bomb?

In the final weeks of World War II, a team of Germany’s most talented scientists launched a last-ditch effort to make an atomic weapon.

It was known as the B8 battery, a landmark experiment founded on years of research under the direction of none other than renowned Nobel laureate Werner Heisenberg.

Heisenberg stated in a 1947 report Nature The document said B8’s uranium-heavy water reactor was simply “insufficient,” unable to ignite in a self-sustaining chain reaction for lack of a little more uranium.

A study led by materials scientist Timothy Koeth of the University of Maryland now claims that Heisenberg’s project had virtually no hope of success, requiring 20% ​​more uranium and 80% more heavy water than was available in Germany at the time.

Without developing a god-like level of coordination and supervision, Hitler would have been far from creating the weapon of weapons during the conflict.

Long before the famous Manhattan Project was established in early August 1942, another effort was already underway to weaponize half a century of advances in physics. Within months of the first experimental observations of nuclear fission in 1939, Germany was investigating its practical applications in what would become known as Uranprojekt.

The outbreak of war in September led to more destructive research results, and numerous initial reactors, or “stacks,” were built in Leipzig, Berlin and Gottow to study the phenomenon.

Berlin Stack Number 8, or B8, was a chandelier of 664 uranium cubes arranged in concentric rings within a pool of heavy water, surrounded by a wall of graphite.

The theory was quite simple. Natural uranium contains a mixture of isotopes, only a small fraction of which can withstand an explosive chain reaction. The insertion of neutrons into the uranium mixture forces some of them to transform into a more reactive material, such as the isotope plutonium-239.

Huge uranium nuclei emit neutrons simply when they decay. Each neutron released can potentially trigger further decay in surrounding atoms, but only when they move slowly enough for the nuclei to grab hold. Hydrogen atoms with an extra neutron (the kind found in “heavy” water) provide enough of an obstacle course to slow down accelerating particles without absorbing them all. Surrounding the setup with graphite sends stray neutrons back into the game.

To produce plutonium, this process must be self-sustaining, meaning that the release of each neutron must trigger the release of at least one more.

Despite being Germany’s most advanced nuclear stack, B8 failed to reach the critical 100% mark even as Allied forces marched toward the German capital.

For Heisenberg, it may have been a question of needing more materials. Its heavy water supply came from a single plant in Norway which was destroyed in 1944.

However, Germany’s scant amount of uranium ore had been divided between different piles at the project.

“In practice… for more [heavy water] If it were not available, uranium would also be introduced into the graphite reflector, which would probably have been sufficient to achieve criticality,” Heisenberg speculated in his letter to Nature.

Since then, researchers have asked…what if?

Most of Uranprojekt’s cubes have disappeared over the years, disappearing into the post-war black market. But not all. In 2013, Koeth received one as a birthday gift. Intrigued by her story, he and fellow researcher Miriam Hiebert did the math on Germany’s reserves and calculated that there might have been enough there to reach criticality, if they had been pooled in one place.

After further research, Koeth isn’t so sure.

A more thorough study involving two of the cubes and historical documentation showed that Heisenberg’s sums were accurate: B8’s neutron multiplication factor was a few short of the 100 needed for a self-sustaining reaction. The entire experiment would have required twice as much uranium to operate and more than twice the volume of heavy water.

The team discovered that there simply wasn’t enough of either scattered among the piles. Even a few adjustments to the experiment to replace a layer of graphite with heavy water would have failed, given the purity of the materials available.

Did Germany ever have the opportunity to build an atomic bomb? Perhaps that is a more difficult question to answer. In another universe, with different mindsets and higher project prioritization, some might argue that it was possible.

Fortunately, that is not the universe we live in now.

This research was published in PNAS Nexus

Source: Eurekalert