post by lunarminer
Both the Germans and the Japanese had advanced weapons programs. All of this information came out during the 80's and 90's well after most of the witnesses were dead.
I never heard of the German reactor, the German uranium shipments to Japan, the Japanese uranium mines, the heavy water plant in North Korea, the rumor of a successful bomb test, a Japanese bomb design. All of this came after I was in college.
At the risk of repeating what we already know, keep in mind that uranium in its natural state - yellow cake - is 99.7% U238 and the isotope U235 - the fissionable one - is 0.3%. Because it is chemically impossible to separate the two, the world was at an impasse.
The US choose to use the gaseous magnetic method. Other methods were suggested but this seemed the most likely to work. We now know that the centrifuge method also works and costs a lot less.
The major problem with the gaseous magnetic system is it needs so much electricity. The Army built the largest building under one roof in Oak Ridge, Tennessee, in which to carry on the process. Aside: copper was in short supply, so the Army called on the US Mint to furnish about 10,000 tons of silver to be made into wire for the devices. About 1,400 of the devices were connected in series.
The raw uranium was vaporized, injected into the first device and the electricity was turned on. As the vaporized uranium passed through electrically charged membranes, moving from one device to the next, the U235 would come through first. As you repeated the process endlessly, you gradually purified the uranium to a higher level of U235. They say 3% purity is OK for running a power plant but 70% or better purity is needed to make a bomb.
I have posted elsewhere that the US used 10% of ALL the electricity in America to run Oak Ridge. Neither Germany nor Japan had such a supply of electricity. They might well have known how to make a bomb, but they lacked the industrial capacity to purify enough uranium to make bombs.
Heavy Water. Heavy water is chemically the same as regular (light) water, but with the two hydrogen atoms (as in H2O) replaced with deuterium atoms (hence the symbol D2O). Deuterium is an isotope of hydrogen; it has one extra neutron. Thus the deutrium atom consists of one proton and one neutron in the atomic nucleus and one orbiting electron. It is the extra neutron that makes heavy water "heavy", about 10% heavier in fact.
Heavy water is essential to the operation of Canada's nuclear power reactors; used as both a moderator and a heat transfer agent. The function of the moderator is to slow down the emitted neutrons, which increases the fission reaction rate, thus enabling a sustained chain reaction. Ordinary water is also a good moderator, but it absorbs neutrons, which is why light water reactors must use enriched fuel. The use of D2O in CANDUs makes it possible to use non-enriched natural uranium.
Heavy water is produced at Ontario Hydro's heavy water plant 'B' at Tiverton, Ontario. The heavy water is not manufactured, but rather it is extracted from the quantity that is found naturally in lake water. The water is separated through a series of towers, using hydrogen sulphide as an agent. Canada is the world's supplier of heavy water.
It is important to note that heavy water is not radioactive, nor is it dangerous to humans or other life unless ingested in large amounts (it becomes toxic to humans at a level of roughly 10% of their body weight). The deuterium isotope occurs naturally in the ratio 1:4500; thus D2O is found at the level of about 1 in 20 million water molecules. www.sno.phy.queensu.ca...