AginAf wrote: ↑13 Sep 2018, 04:53
As I understand it, we discovered at the onset of occupation in 1945, that the Japanese had had two nuclear weapon development programs on going at surrender. As was typical of them, one was conducted by the Imperial Army, and was based at several sites in Tokyo. The other was the Imperial Navy's, and was based in the port Wonsan Korea near the source of uranium in Manchuria.
Our experts were able to determine that the Army program was not very well along - years away from test. But we were unable to determine what the Navy had going because Wonsan and all of North Korea were occupied by the Soviets at the end of hostilities.
Then, in 1950, a Japanese nuclear physicist was granted an exchange with the University of Arkansas in the US' He disclosed that he had worked on the IJN's program during the war, and that they had successfully tested a breadboard bomb in the week between our first strike on Hiroshima, and our second on Nakasaki. US intelligence was unable to confirm this, and the Soviets, out to develop their own bomb thanks to secret data passed them by US & UK communist traitors, were not going to enlighten us.
The US AEC finally drew the conclusion that at best, the test was a low order explosion, but that is a guess
IF this is all factual, and the Japanese were enriching Manchurian U-235, then the IJN would have had no need of the U-234's cargo, because the Sons of Nippon were on the cusp of developing a weapon made from East Asian sources. One wonders how long it would have taken them to develop a weapon they could have loaded in one of their newly developed jet powered Baka kamikaze planes or their new 6 engine heavy bomber, or one of their suicide submarines and popped it in in the 7th fleet anchorage, thus turning the tide of the war.
This is a pretty accurate summary. I have a few "down in the weeds" details to add if it's not too pedantic.
I would generally agree that the IJA's nuclear weapons program was located largely on the Japanese mainland. However, there is also a slim tendril of documentation alleging that the Kwantung Army in mainland Asia / Manchuria was itself working on nuclear weapons. This was as a direct result of Japan's defeat-in-detail at the hands of the Russians at the Battle of Khalkin Gol, during the undeclared border war in 1939, When I visited the US National Archives in person at the Suitland, MD, headquarters, I found exactly one (1) document that made a brief mention of the Kwantung Army project. This came directly from Yoshio Nishina, who was himself the lead scientist of the Army's mainland nuclear weapons project under the supervision of the Tokyo Arsenal and its related Army bureaucracy. Naturally, I had just one photo of this one page document and it was the one that I lost (accidentally deleted from my laptop), out of more than 200 that I took. I do, however, remember the names of two National Archives Record Groups, and Nishina's statement is in one of them. It was either G-2 US Army Far East Intelligence Summaries from the very end of the war and the years immediately afterward, or it was in the files of the 5250th, which was a technical intelligence investigation unit whose members included a certain Captain or Major Kelly. Kelly's interrogation via interpreter of a Japanese technician who had escaped or defected from the Hungnam area is included in the 2nd edition of Robert Wilcox's book,
Japan's Secret War.
Anyway, Nishina's statement is in one of those two boxes, if anyone reading this wants to make the trip to the Archives themselves and dig it out again. Nishina was telling US Occupation authorities that he personally knew another Japanese scientist who, during the war, had been working on the atomic bomb for the Japanese Army in Manchuria---presumably for the Kwantung Army---and that this scientist, who is not named in the document, was now working on nuclear weapons for the Chinese Communists. Given that the Communists won the Chinese civil war in 1949 and that Nishina died of cancer in 1951, it would put his statement between 1949 and 1951. There is exactly one (1) OSS document that I know of which alleges some kind of Japanese nuclear test in the Gobi Desert, apparently connected to the Kwantung Army project. It is my understanding at this time that the effort in Manchuria was separate from the mainland Project
Ni, though Nishina's knowledge might indicate that the two centers of R&D were somehow connected, since Nishina himself was working for the IJA. It's difficult to say because although the Kwantung formation was nominally subordinate to the IJA high command, in practice it functioned more like a state within a state, similar to what the SS ultimately became in Nazi Germany. According to "machinga", an occasional poster on this forum and in this thread who is himself a very well-informed researcher in this subject, the OSS document is found in a larger group of papers known as "Project Verona". Note that this is not the same as "Project Venona", the US Army counterintelligence program that outed a large number of communist moles, spies, and sympathizers in the US government of that era.
As for Japan enriching U-235, my tentative summary at this time is that I don't think they had enough machinery to produce enough of it, fast enough, to complete enough bombs soon enough to turn the tide of the war. Unless they had a reactor (which would mean U-233 or P-239 rather than U-235), or one or more large separation - enrichment installations buried in the mountains in North Korea, they would have needed help---obviously from Germany---to acquire sufficient amounts of fissile material. As to how much they needed, my initial idea, as I described more than a decade ago in the very early days of this now gargantuan thread, was that Nishina's concept was probably for a gun-type bomb broadly similar to the US Little Boy device, as this would have been far and away the easiest to engineer and to build. However, that was an assessment I made before I got the chance to read a complete translation of the Kuroda Papers, aka the Tonizo Report. The original documents reveal that Nishina was certainly thinking about a U-235 bomb and performed a number of advanced calculations concerning it, but some of his wording---at least as it appears in the English translation I have read---might indicate he had in mind an implosion bomb rather than a gun-type weapon. J. Robert Oppenheimer sent a memo to General Groves immediately after the Little Boy bomb was dropped in which he urged the immediate junking of that design in favor of building modified, U-235 Fat Man bombs. Nishina was certainly and easily a good enough physicist to have realized the same advantages inherent in a much more efficient implosion bomb.
I am curious as to the identity of the Japanese nuclear physicist "granted an exchange with the University of Arkansas". If you mean Dr. Kazuo "Paul" Kuroda, he in fact served on the faculty of that school for many years and was involved in the WWII Japanese nuclear weapons effort, but he worked with Nishina for the Army, not the Navy. If there was another scientist who also came to the University of Arkansas other than Kuroda, that is news to me and I would like to know who that was.
