Norwegian Heavy Water Sabotage - Technical Background

Technical Background

Enrico Fermi and his colleagues studied the results of bombarding uranium with neutrons in 1934. The first person who mentioned the idea of nuclear fission in 1934 was Ida Noddack. After the Fermi publication, late in 1938, Lise Meitner, Otto Hahn and Fritz Strassman confirmed nuclear fission. Physicists everywhere realized that if chain reactions could be tamed, fission could lead to a promising new source of power. What was needed was a substance that could "moderate" the energy of neutrons emitted in radioactive decay, so that they could be captured by other fissile nuclei. Heavy water and graphite were the prime candidates for moderating the energy of neutrons.

When Nazi Germany investigated the production of an atomic bomb (see German nuclear energy project), a range of options were identified. Although historical records provide limited detail on the German decision to pursue the heavy water approach, it became clear after the war that they had explored the option. Although ultimately unsuccessful, the approach chosen has been demonstrated to be technically viable:

• Plutonium-239 (239Pu) makes an effective weapons material (although requiring an implosion-type mechanism as a simpler Thin Man gun-type bomb is not feasible).
• Heavy water has been demonstrated as an effective moderator for 239Pu production.
• Heavy water may be separated from regular water by electrolysis.