carmendrahl writes: Tomes upon tomes have been written about the history of Germany's nuclear program in the 1940s (see Heisenberg's War, or The Making of the Atomic Bomb). Now, an international team has conducted nuclear forensic analysis of three WWII-era uranium samples from Germany. The results strongly suggest that in their wartime experiments, Germany's researchers never achieved a self-sustained nuclear chain reaction-- the chemical underpinning of atomic weaponry. The study appears in the journal Angewandte Chemie . Led by Maria Wallenius of the European Commission's in-house science service, researchers examined samples of uranium from two "Heisenberg cubes"- named for Werner Heisenberg, and a "Wirtz plate"-- named for Karl Wirtz. The team measured ratios of isotopes of the elements uranium, strontium, plutonium, and thorium. They also measured abundances of certain rare earth elements. They verified the samples as authentic, dating them to the early 1940s, and localizing the area where the uranium ore was mined to the Czech Republic (which was under Nazi control at the time). They also demonstrated that the isotopes of uranium-236 and plutonium-239 occur in levels matching what would be expected naturally. ”This suggests that the uranium samples have not been exposed to a significant neutron fluence," Wallenius said in a statement.