Hitler's Terror Weapons by Brooks, Geoffrey (life books to read .txt) 📗

part of the boat gave uniform Geiger counter readings over its entire surface? Men lived for months in close proximity to this radioactive contamination, yet none complained of radiation sickness. How was this to be explained?

Lt Colonel Richard Thurston, a former member of the Manhattan Project radiological team, supplied the answer137: the radiation could not have been gamma radiation. What occurred to him was that all the reported conditions could only be met if the substance detected was radon gas, which is notoriously difficult to contain. It would seep through the containers and steel tubes and adhere to exposed surfaces but not be particularly dangerous to humans.

Radon gas would imply the presence within the containers of radium in some form. A radium-beryllium source within a small sphere of heavy water at the centre of uranium oxide in a gold-lined cylinder would amount to a sub-reactor in miniature and meet the request of the Japanese for “a quantity of uranium oxide” in connection with their atomic research into the fissile isotopes including plutonium.

Pfaff’s warning that the material must be handled like crude TNT indicates that the same precautions apply to the material as for the most unstable explosive. This is because the substance within the small cylinders becomes sensitive and dangerous on exposure to air. If these gold-lined cylinders were miniature sub-reactors, then the following dangers would present themselves when the cylinders were opened:

(1) Plutonium particles from the irradiated uranium oxide would rise into the atmosphere. The inhalation or ingestion of 1mg of plutonium will result in the lingering death of the victim within weeks and even a microgram results in a later high susceptibility to pulmonary cancer.

(2) Dangerous neutron radiation would be emitted from the reaction of the radium-beryllium source as would gamma and corpuscular radiation from the products of fission decay in the uranium powder.

This was why it was so dangerous to open the cylinders. The use of a gold lining in addition to the lead shielding is the clearest possible indication that a reaction process was continuing in the cylinders, and Professor Nishina of the Imperial Japanese Army nuclear project would have received, on the arrival of U-234 in Tokyo, ten cases of uranium oxide containing precisely what had been requested in the Magic signals.

The cylinders though dangerous were basically nothing more than an elementary research material for the laboratory and would not have led the Americans to panic and suspect that Japan was on the verge of developing an atom bomb.

The Eighty Small Heavy Cases

To the exclusion of everything else aboard U-234, these eighty small containers in the custody of Major Vance, the tests performed on them by the Manhattan Project, and their ultimate disposal, are the obvious basis for further research.

They were removed from their loading tube at the end of May. Aboard the submarine there was no mystery as to where they had been stowed for probably half the crew had worked on the loading that day in February and the contents excited interest by their unusual weight. Portentous omens have been read into the meaning of the symbol “U-235” painted by Tomonaga on the wrapping of each of the small containers, but probably it served merely to identify the consignment as being uranium. I have no idea what the correct chemical formula is for natural uranium enriched with plutonium isotopes, and I doubt if Tomonaga would have known either: if on the other hand the cases actually had contained the isotope, it is unlikely in the extreme that the fact would have been advertised to all and sundry on the quayside: the Japanese, past masters of deception, even disguised their initial interest in uranium as being a sort of “catalyst”.

The New Hampshire evening paper Portsmouth Herald announced in the week following the capture of U-234 that the submarine had been “headed for Japan for the purpose of aiding Japan’s air war with rocket and jet planes and other German V-type bombs”. This is the first reference from a source well-connected to the US Navy to a “V-type bomb” and a “jet plane”, neither of which feature on the Unloading Manifest. And in June the same newspaper claimed that there had been sufficient uranium aboard U-234 to produce an explosion to eradicate all of Portsmouth and its surrounding suburbs from the face of the earth. Newspaper reports must, of course, not be awarded too much credence as historical documents, but they are nevertheless useful pointers. The Portsmouth Herald knew about a “jet plane” aboard U-234 which is claimed by the German crew to have been shipped, but as to which the official record on the American side is silent. And to what extent before the first Trinity test in July 1945 was the effect of fantastic explosives openly discussed, and where did the idea come from that such a substance was aboard the German submarine?

Lt-Col John Lansdale, chief of atomic security and intelligence for the Manhattan Project, admitted that he handled the disposal of the small cases aboard U-234.138 He recalled that the American military authorities reacted with panic when they discovered the cargo aboard the U-boat. Lansdale went on to say that the German material was sent to Oak Ridge where the isotopes were separated and put into the pot of material used to make America’s first atom bombs.

Obviously Lansdale did not mean U235 isotopes here since they are the final result of the separation process. The only fissile isotopes which can be separated from irradiated uranium are the range of plutonium isotopes from fissioned material bred in a working reactor or sub-reactor assembly. This would have made them panic, particularly if they knew how a small-scale German atom bomb was constructed. All that was needed for detonation would be an effective implosion fuse.

Natural uranium powder in its natural state is highly pyrophorous and ignites spontaneously on contact with air, but this would not require it to be packed in eighty small radioisotope containers. It is, however, the manner in which plutonium-enriched