Overview
- A peer‑reviewed paper published Sept. 29, 2026 used material forensics, archival records, and three physics simulations to reassess Germany’s final B8 reactor experiment.
- The team measured two surviving uranium cubes and ran models benchmarked to projects like Chicago Pile 3 to recreate B8’s conditions and match Heisenberg’s original readings.
- Their simulations found B8 needed roughly two times the uranium and about 2.1–2.4 times the heavy water the pile actually held to reach criticality.
- Available heavy water was a decisive bottleneck because the study estimates the reactor would have required about twice the heavy water that Norsk Hydro produced for Germany during the war.
- The paper concludes that boron impurities in German graphite would have prevented a graphite‑moderated design from working and that these material shortfalls overturn Heisenberg’s postwar claim that a small extra supply of uranium would have let B8 succeed.