The Japanese nuclear weapons program

Discussions on all aspects of the Japanese Empire, from the capture of Taiwan until the end of the Second World War.
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williamjpellas
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Re: The Japanese nuclear weapons program

#481

Post by williamjpellas » 02 Oct 2018, 17:09

Wilcox and others have documented far greater expenditures by the Japanese on their nuclear R&D than what you mention here. They paid prodigious sums looking for uranium on the black market on the Asian mainland, for example. In any case, 40,000 yen wouldn't have built Nishina's 5 cyclotrons, or Arakatsu's Cockroft-Walton accelerator, his own cyclotron, or his ultracentrifuge, nor Suzuki's thermal diffusion separators based on NIshina's prototype. So, far more money was spent, quite obviously.

The citation for the MAGIC intercept you quoted is incorrect or at least incomplete. The complete "address" in the US National Archives includes considerable additional information, such as the Record Group (abbreviated "RG"), its physical location including the shelf where the box containing the papers is found, and so on. I know Wilcox quotes that particular document in Secret War. The complete citation is found in the index.

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Re: The Japanese nuclear weapons program

#482

Post by Genro » 05 Oct 2018, 15:42

I can only quote what is written in the document for 2nd July 1943. My estimate is based on the cost of a bath house which at the time was about 15 sen ( 100 sen = 1 yen) . This would be a very common custom, a social gathering though less so today and which is now about 450 Yen. Obento at that time was about 30 sen and most people would have made their own to take to work but today it’s about 800 yen. Based on that, 2000 yen would be equivalent to about 40,000 £ or 50,000$. If I was given a grant like that I would not turn it down unless I was being asked to make an atomic bomb.


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Re: The Japanese nuclear weapons program

#483

Post by Genro » 05 Oct 2018, 17:58

My original question was why would Japan test an atomic bomb, the USA thought it was unnecessary?
Memo from General Groves to the Chief of Staff [Marshall] ,7th August 1944, Top Secret.
Based on present knowledge we would be willing to recommend the dropping of the first bomb in combat operation without prior test.

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Re: The Japanese nuclear weapons program

#484

Post by williamjpellas » 06 Oct 2018, 21:48

Genro wrote:
05 Oct 2018, 17:58
My original question was why would Japan test an atomic bomb, the USA thought it was unnecessary?
Memo from General Groves to the Chief of Staff [Marshall] ,7th August 1944, Top Secret.
Based on present knowledge we would be willing to recommend the dropping of the first bomb in combat operation without prior test.
Assuming for the sake of inquiry that at least one or two prototypes in some form were completed and set off, I can give you several possible reasons why Japan would find it necessary to test an atomic bomb, as opposed to the the USA, which "thought it was unnecessary".

1) Maybe it was a different kind of bomb? It is known that the Germans were interested in boosted fission as a more efficient method of detonation. The Germans also explored other methods of producing a superbomb. Some of them were off the beaten path compared with the more "standard physics" being utilized in the Manhattan Project, but that doesn't necessarily mean the German approaches wouldn't have worked.

2) Did any of the German R&D make its way to Japan? Was it incorporated in some way and to some extent in the end of war crash project in Korea?

3) Was it an implosion bomb? The German Schumann-Trinks device definitely utilized implosion, or would have if it had been built (as some allege). The Manhattan Project DID test its own implosion bomb, at Alamagordo a few weeks before dropping the same model on Japan at Nagasaki.

4) Maybe the Japanese version really was a simpler gun-type device, but their scientists just had a different methodology or weren't as certain it would work.

Etc.

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Re: The Japanese nuclear weapons program

#485

Post by Genro » 07 Oct 2018, 15:22

The most probable assembly method would be the ‘gun-barrel’. This would be the obvious approach though Frisch and Peieris did initial propose the use of metal springs but it was the concept that was important. Both Serber and Heisenberg realising the importance of spontaneous fission, both came to the conclusion that an assembly velocity of 3000 ft/sec or 1000 meters/sec would be required. While Serber considers 100% U235, Heisenberg realises that it would probably be less than100% and that the spontaneous fission of the U238 content possesses a problem. For 64 Kg of 80% U235 (little boy), the spontaneous fission rate of U 238 during the 100micro-seconds of final assembly is about 0.012. Given that some neutrons would be lost at the surface so say 0.01, the chances of a failure are about one in a hundred.

While there is no mention of assembly method in the Tonizo documents the presents of spontaneous fission was understood as in Hagiwara Tokutaro paper of 30-Nov-1943.
U 238 S.F. 4x10^15 Y: U 235 S.F. 3.5x10^17 y.

Note;
https://en.wikipedia.org/wiki/Godiva_device
Godiva's design was inspired by a self terminating property[further explanation needed] discovered when incorrectly experimenting with the Jemima device in 1952.
Wiki does not offer an explanation for a self-terminating nuclear chain reaction but here it is in Japanese and English.

Y, Nishina, 2nd February 1944. Riken Institute, Tokyo.
計算によると________即ち反応のため発熱を伴い膨張し、従ってウランの濃度を低下することとなる。濃度うすくなれば反応が止まるまでになるのではないか。しかる場合温度低くなり、再び濃度を増す関係上反応行わる。以上は理想的の場合であって実際は未だ不明なり。
According to calculations______ that is to say the reaction will cause the temperature to rise and will simultaneously expand. Therefore the uranium density will fall, this is what will happen. * This will cause the concentration to diminish until the reaction comes to a halt. If this is correct. In this situation the temperature will fall and again, as the density is related to this, the reaction will recommence. This assumes an ideal situation and is not known for sure.

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Re: The Japanese nuclear weapons program

#486

Post by williamjpellas » 07 Oct 2018, 17:22

AginAf wrote:
13 Sep 2018, 04:53
The US AEC finally drew the conclusion that at best, the test was a low order explosion, but that is a guess
AginAf, I just now noticed your reference to the postwar AEC---the Atomic Energy Commission. Apparently they studied the WWII Japanese work? I had never encountered this assertion before, though it makes sense given the AEC's status as the successor to the Manhattan Project. Have you seen any document or report from the AEC about the Japanese bomb projects? I would love to have a copy for my files if you have anything. Feel free to PM me, and thank you.

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Re: The Japanese nuclear weapons program

#487

Post by Genro » 08 Oct 2018, 14:47

Masakaktsu Yamazaki. ( Tonizo documents)

In this document the most notable point is that Nishina had thought then that the state of an out of control nuclear reactor was equivalent to a bomb. From the article that was written by Nishina in the magazine (World) in March 1946, this fact had been expected but it was confirmed for the first time in the original wartime document (Tonizo). The authors are currently working on a document to interpret the technical aspects and plan to publish at a later date. ( Cannot find any such further publication.)
Japan times. 7 March, 2003.
Japan’s A-bomb goal still long way off in ‘45.
‘Historians say that not only had Japan’s scientists underestimated how much of the rare isotope uranium -235 they would need for the bomb, they misunderstood the mechanics of an atomic explosion’.
‘The papers show that Nishina believed he could fashion a bomb from 1 Kg of weapons grade U-235 with 1 -2 tons of natural uranium ore.’
‘But at the root of Japan’s failure was Nishina’s flawed theory about an atomic bomb’.
‘To generate an atomic explosion, Nishina knew he had to trigger a chain reaction of U-235. Experts agree that has to occur within 1/200th to 1/300th second. In the documents, Nishina says he thought he could do it in 1/20th to 1/30th second.’
“ Yamazaki said. “Only years after the war did he realize that his calculations were wrong”.
KAKEN, Tokyo Institute of Technology 1999.
The critical mass problem in both the Army and the Navy were studied in detail, and we found that the notion of Nishina's atomic bomb was a nuclear reactor out of control.
In my opinion none of this is true but neither is much of what is written by western authors.

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Re: The Japanese nuclear weapons program

#488

Post by williamjpellas » 29 Oct 2018, 02:39

In my opinion none of this is true but neither is much of what is written by western authors.

That Japan Times piece is really odd. I have no idea what Yamazaki was doing, unless he was either 1) not qualified to interpret or draw any sound conclusions about what was in the Tonizo Report / Kuroda Papers but the Times went ahead and quoted him anyway, or 2) deliberately mouthing disinformation because he, or some people in Japan, or both, thought it would be a good idea to try and publicly dismiss or downplay the idea of a WWII Japanese atomic bomb project (or more than one, as was actually the case).

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Re: The Japanese nuclear weapons program

#489

Post by Tiger B » 14 Nov 2018, 02:16

Genro wrote:
28 Sep 2018, 20:20
To clarify this neutron attenuation by gold the neutron capture cross-section for fission neutrons is given as 0.077 barns and for the scatter As 4.3 barns. ( 1 barn = 10^-24 cm2) Neglecting capture which is small in comparison, the attenuation No/Ni with thickness d is given by e^-d N As were N is the number of atoms cm3. N = p Av/Aw, p = density 19.3, Av = Avogadro’s constant 6.022 x 10 ^23 and Aw the atomic weight 197. Putting these together for d = 10 cm gives No/Ni = 0.08 about 10%.
What is the reaction of high energy neutrons to a salt water environment? Doesn't gold change the nature of the capture ratio to something like an X-Ray scatter? If you don't want the 'U234' reacting to the salt water in/around the mine tubes, with accelerated corrosion and/or reactive (boiling?) chemistry effects, doesn't it make sense that you would use gold to alter the refractory index of the actual case materials?

I had read that the actual value of the gold was only about 50,000 dollars. Could Pfaff and the navy welder have even manipulated casks with a 10cm lining?

In any case, surely this price is rather unimportant compared to benefits of giving Japan the weapons which could have prevented Eisenhower from enacting the horror of Rhineland Camps which mass murdered nearly 1.5 million German POWs?

Is this not what 'five minutes past midnight' means?

I also believe that when Pfaff talks about 'crude TNT' you are discussing the known pyrophoric and explosive properties of the precursor DNT which, of by the way, is also highly toxic. He would not be making light of handling such a chemical in proximity to a blow torch, even simply to cut away the seals.

IMO, this has reference, not to U234 or even U235 but to Plutonium. Five hundred sixty kilograms of Yellow Cake doesn't get you a single weapon. Five hundred sixty kilograms of Pu239 or Pu240 is a whole arsenal. Japan didn't have time to refine even weapons grade material, by the time U234 would have reached Jakarta, it would have been late June at best. Another IJN submarine trip to the home islands and you are talking weeks, at most, before the USAAF is dropping more than incendiaries on you.

Plutonium has two problems however: First you pack it safely and then you must initiate it in a way that doesn't explosively dissemble before critical. That's a boosted system. That's what Von Arden was working on, at the end of the war with his 'lithium iodides for medical purposes' from salt brine and feldspar. That is LD6 before we even knew what that meant.

The alternative is that Pfaff's translation is also messed up and what they are talking about is an LMCT binding agent as a charge transfer salt.

What is noteable about these ligand-metal bindings is that they have a very weak covalent bond (they are low level plasmoids acting as temporary binding agents with a charge transfer) and thus have a very intense optical color discharge.

And where have we heard that before? Oh, that's right, Xerum 525, 'Red Mercury' and a few other labels for a brilliant cherry red substance with enormous capacity to energize conventional explosives, most likely through a higher isomer metastable state condition.

There are more ways to get a nuclear reaction than simply slapping radiomaterial together with sufficient mass to get an RCR. Fusion weapons are boosted weapons which have flipped back to fission excitement with the THERMAL COMPRESSION of heavy hydrogen causing a massive jump in neutron production. As is released from Tritium or LD6 packets which have a thermal index boosted beyond conventional chemical explosive boundaries to energetics release rates.

If this is the case, and given Plutonium is a handful to transfer under the best of conditions, Pfaff did not say 'like' TNT. He said _TNT_. And he meant Pu-239.

Uranium, as you yourself state, is radiologically harmless until well above 50% concentration. You can contain the alpha/beta with a cloth sack.

Plutonium means that the Germans had a functional reactor of their own. Which makes sense since one of the components on the U-234 lading list was 'Haspekerne' or Core Clamps which generally refers to ceramo metallic oxide clamps for wiring bundles in or near the core of a (breeder) reactor that don't produce X-Rays which mess with instrumentation readings when exposed to particle radiation. The Germans would not have those, nor would the Japanese need them, if their atomic programs were not a LONG ways further down the road than 'untested theory'. Or if they were gun-focused.

When will we wake up and put the clues together? The good guys did not win the race to atomic weapons. The bad guys figured out a way to make them smaller, hotter and less radio fuel dependent.

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Re: The Japanese nuclear weapons program

#490

Post by williamjpellas » 22 Dec 2018, 07:03

When will we wake up and put the clues together? The good guys did not win the race to atomic weapons. The bad guys figured out a way to make them smaller, hotter and less radio fuel dependent.

I think this is a distinct possibility, but I need to see more evidence. Just a guess, but if the German devices you describe existed, I get the impression that they had more to do with fusion than with fission (though they appear to have utilized both) and to have had lower explosive yields than the more crude devices produced by the Manhattan Project. Unfortunately a great deal of paper and other evidence was destroyed or suppressed after the war. Some has trickled out, enough to confirm that there were a number of black projects having to do with nuclear weapons going on in both Germany and Japan. In general, it appears to me---as Derek de Solla Price and Eri Yagi indicated in their 1962 Bulletin of the Atomic Scientists letter---that "the German projects were along significantly different lines" compared with the Japanese version. Japan, ironically, appears to have been much closer to what we might call "Oppenheimer Physics" or "The Oppenheimer Tech Tree" than they were with whatever Germany was doing.

However, there is always the possibility that German technology and R&D made its way to Japan, either during the war in Europe, or immediately after it. Thus it may be that the last gasp effort centered in Korea might have been attempting to replicate a bomb or type of bomb along German lines. It is another line of inquiry to be pursued.

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Re: The Japanese nuclear weapons program

#491

Post by Ironmachine » 22 Dec 2018, 11:39

Tiger B wrote:When will we wake up and put the clues together? The good guys did not win the race to atomic weapons. The bad guys figured out a way to make them smaller, hotter and less radio fuel dependent.
If the good guys are the Western Allies, then they did win the race to atomic weapons: They were the first to use them in combat... :lol: :lol: :lol: :lol: :lol:

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Re: The Japanese nuclear weapons program

#492

Post by williamjpellas » 05 Jan 2019, 03:28

There is actually one MAGIC intercept of a Japanese radio transmission which claims that the Germans were the first to use some form of nuclear weapon, on the Eastern Front.

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Re: The Japanese nuclear weapons program

#493

Post by Genro » 07 Feb 2019, 12:12

‘However, there is always the possibility that German technology and R&D made its way to Japan.’

I have always wondered just how much cooperation existed during the alliance between Germany, Italy and Japan. The following would give the idea of a somewhat ’frosty’ relationship, certainly at a diplomatic level.

In the early part of 1938, several thousand Jewish refugees congregated at Otpor, a railway station on the Russian Manchuria border requesting permission to travel to Shanghai and Japan. General Kichiro Higuchi who was in charge of the army in Manchuria forwarded the request to Tojo on humanitarian grounds and Tojo agreed. Hitler was furious and instructed Ribbentrop the foreign minister to demand that Higuchi be punished but Tojo did nothing for a few months and then promoted Higuchi.

Then in 1940 Matsuoka the foreign minister gave the following speech (he was fluent in English):-
” I am the man responsible for the alliance with Adolf Hitler, but nowhere have I promised that we would carry out his anti-Semitic policies in Japan. This is not simply my personal opinion, it is the opinion of Japan, and I have no compunction about announcing it to the world”.

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Re: The Japanese nuclear weapons program

#494

Post by Genro » 09 Feb 2019, 15:29

Information on direct cooperation in atomic science between Germany and Japan during the war period is difficult to find. Nishina and Heisenberg were fellow students and prior to the outbreak of war Heisenberg did visit Japan for a lecture tour at Nishina’s invitation.

In the Farm Hall transcripts Bagge and Korsching do discuss the work of Yukawa but this is a very esoteric subject compared with that of an atomic bomb. In the conversation between Heisenberg, Hahn and Hartek. Hahn mentions Nishina’s discovery of U237 and symmetric fission, “ In this instance the Japanese for once published something original, it appeared as if these Japanese elements, as we called them came out.”
This is of course a translation of the German recording and may be a little garbled if the translatorwas not familiar with the subject

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Re: The Japanese nuclear weapons program

#495

Post by Genro » 11 Feb 2019, 15:18

Takeo Yasuda.
From Wikipedia.
Between 1942 and 1944, Yasuda was commander of the Tokyo-based IJA 1st Air Army, head of the Army Aeronautical Department and Inspectorate General of Aviation, being relieved of duty in April 1944. He was a strong advocate of the use of suicidal ramming tactics against American bombers. Serving as a member of the Supreme War Council during the final years of the war, Yasuda also returned to command of the IJN 1st Air Army as part of the preparations for the final defense of the Japanese home islands against Allied invasion, however, he retired shortly before the war's end.

From the Japanese text we find that Yasuda was NOT a strong advocate of suicide missions but instead opposed them. The phrase ‘e-wo tonareru’ meaning to opposed but has the nuance of a strong vocal form. Tojo personally had him ‘ kotetsu sarata ’ meaning reassigned as opposed to ‘sareru’ is dismissed. ( ‘ kotetsu’ has a somewhat negative nuance.) .
Yasuda’s position was then taken over by Ushroku Jun who was eventually capture by the Russian while in China. He was found guilty by the Russian court as a class A war criminal and sent to a prison in Siberia, eventually returning to Japan 11 years later.

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