Free Hitler's Terror Weapons by Geoffrey Brooks Page B

for a minimum supply of 600 kilos of uranium oxide.
    At the end of May Diebner loaned him 50 kilos and Dr Riehl of the Auer Company brought him 135 kilos more. Heisenberg sent nothing. When the block of ice arrived at the beginning of June the experiment was doomed and the only useful information it yielded was criteria for the distribution of neutron density in certain arrangements of uranium oxide and dry ice 44 .
    Heisenberg’s non-cooperation prevented Harteck from obtaining a figure for neutron multiplication. This would have enabled Harteck to calculate the quantity of materials he needed for a working pile. Both Harteck 44 and Wirtz 45 made this point subsequently.
    A Windfall of Uranium Oxide: Harteck Tries Again
    There was no shortage of uranium oxide in German-occupied Europe. In May 1940 German forces arriving at Oolen in Belgium had discovered at the warehouses of the Union Minière Company over 1200 tons of uranium oxide and 1000 tons of other refined uranium metals. The British Government had known about this stock since early 1939 but had dropped a plan to purchase it outright and so remove it from proximity to Germany. The President of Union Minière, Edgar Sengier, appears to have made a purely business decision to leave the material for the Germans when they invaded so that his company would find favour with Hitler should he emerge victorious in the coming war in western Europe. Sengier then ordered the uranium mines at Katanga in the Belgian Congo flooded and had the mined ores shipped from Lobito to the United States. In October 1939 he transferred his offices to New York 46 .
    The Germans controlled the Joachimstal mines in Czechoslovakia and thus held virtually all the uranium in Europe. There was in fact so much uranium in their hands that Professor Harteck set about planning his ambitious second experiment, a heterogeneous design consisting of 20 tonnes of uranium oxide in a lattice of shafts embedded throughout a 30-tonne block of dry ice. As soon as he announced his intention, he ran up against the determined opposition of Heisenberg, who argued that the experiment was so big that all Harteck would learn from it was a great deal about 20 tonnes of dirty uranium oxide and 30 tonnes of dry ice. Why Harteck thought that was something worth knowing he could not imagine. He expected that it would not work, however, or at least not unless Harteck sent the uranium oxide to a factory for purification first.
    Harteck then came under growing pressure from other quarters, probably orchestrated by Heisenberg, and these argued that it was too extravagant for a first experiment to use 50 tonnes of materials to do the whole programme at once, while Heisenberg returned to the attack by remonstrating about the unprofessional approach to the experiment.
    Bitterly Harteck was forced to concede defeat, refusing to accept their opinion. He resented Heisenberg in particular, commenting that, to his knowledge, Heisenberg had never contributed a single basic idea leading to the solution of the problems of nuclear fission: he found it inexplicable that a theoretical physicist who had never been involved in a large experimental venture could be appointed as leader of a technological enterprise. It was worse than merely poor judgment. Harteck attributed Germany’s failure to produce a nuclear weapon to the antagonistic attitude existing between the theoretical physicists and the experimentalists: the former considered the latter as beneath them, “a few egoists pushed the others aside”. 47
    What seems to have been Heisenberg’s real worry over Harteck’s proposed reactor was that since it operated at sub-zero temperatures it might be easier to stabilize it with control rods when it went critical: if this sort of primitive reactor worked, it would produce the nuclear waste which Harteck wanted to use in radiological weapons. Harteck felt sure that such a programme would have brought the war to a