560 kilos of uranium oxide was shipped to Japan in the U-234. That amount of uranium oxide contained about 3.5 kilos of U-235. That is about 1/5th-1/3rd the amount needed to make a nuclear bomb. The material certainly found its way to Oakridge but there is no way of knowing specifically what device it was used in.
The Japanese had a substantial amount already gleaned from scouring China for their nuclear research facility in North Korea. They had developed gas centrifuges to refine uranium back in the 1930s. The Germans got into that technology about 1942. The benefit was the lack of heavy water needed. Decrypts of messages point to Germany/Japan transfering this technology and material in 1943-44. When Italy capitulated in 1943 a sub with uranium oxide bound for Japan was surrendered in South Africa.
Also on board the U-234 was lots of cargo. Cargo containers were built to fit in the original mine shafts forward, midships and astern. Four cargo containers were carried topside. 240 tons of cargo were loaded for departure March 25,1945. Cargo included three crated Messershmitt Me-262 jet fighters and an ME-163 rocket-propelled fighter, Henschel HS-293 glider-bomb, extra Junkers jet engines, 10 canisters of uranium oxide, a ton of diplomatic mail, and over 3 tons of technical drawings, plus other technology (torpedo, fuses, armor piercing shells, etc.) Passengers were 9 high technical officers (one general) and civilian scientists.
U-219 and U-195 had delivered 12 V-2s to Japan in 1944. U-859 sunk in 1944 was carrying uranium. The U-219 was turned over to the Imperial Navy to become the I.505. The U-195 became the I.506. There were something like 98 known attempts or successful voyages to Japan so we can only imaging what goodies were sent. Certainly the uranium oxide was not the 1st shipment.
