... [N]ew evidence has emerged about the Japanese military's own secret program to build a nuclear weapon.
A retired professor at the state-run Kyoto University recently discovered a blueprint at the school's former Radioisotope Research lab, Japan's Sankei newspaper and other local media reported recently.
The notebooks were related to research work by Bunsaku Arakatsu, a professor at the university whom Sankei said was asked by the Japanese navy to develop an atomic bomb during the war.
Also found were drawings of a turbine-based centrifuge apparently to be used for the study of uranium enrichment. It was dated March 1945. Another blueprint was found of a centrifuge that a Japanese company, Tokyo Keiki, was producing, with a notation indicating the device was scheduled to be completed Aug. 19, 1945 — four days after Japan announced that it was surrendering.
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"These drawings are more confirmation of the Japanese atomic bomb effort, something many in Japan do not want to admit," said Robert K. Wilcox, the L.A. based- author of "Japan's Secret War: Japan's Race Against Time to Build Its Own Atomic Bomb."
Wilcox, who has been researching the program for decades, said Japan's problem was not a lack of know-how.
"They knew the physics needed for creating the bomb and the engineering needed to build it," he said. "It was lack of element resources like uranium that was the real problem for them."
Such supplies were not readily available in Japan so its leaders looked toward occupied territories.
"In 1945, the Japanese navy alone spent a fortune to gather uranium," Wilcox said. "They needed a win-the-war weapon and an atomic bomb was seen as one of those."
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... Wilcox and Japanese scholars who have since studied the matter say there were two programs to produce a nuclear weapon.
The first plan was commissioned by the Japanese navy and code-named F Research, which involved Arakatsu, the professor. The Japanese army carried out the other program, known as the Nigo Research project, headed by Yoshio Nishina, a physicist at the Riken Institute in Tokyo.
Some scholars believe Japan could have made a nuclear bomb if it had succeeded in acquiring uranium and been able to enrich it. Two major setbacks delayed progress, researchers and those involved in the programs have said.
Masa Takeuchi, who had played a central role in researching thermal diffusion under Nishina, said in the 1960s that Japanese researchers had completed a thermal diffusion device that would have allowed extraction of uranium 235 as early as 1944, but U.S. bombings destroyed their secret facilities.
The other problem was that Japan couldn't get enough uranium to move forward, another researcher, Kunihiko Higoshi of Gakushuin University, said in 2013.
"Nishina told us that a U-boat from Germany would bring us the uranium. It never arrived," Higoshi said.
On May 19, 1945, a Nazi submarine was captured and discovered to be delivering 1,200 pounds of uranium oxide to the Japanese military. The vessel was dispatched for Japan shortly after Adolf Hitler committed suicide, a time when the Germans wanted to dispose of their large amounts of uranium. Two Japanese officers were aboard the submarine; both committed suicide upon being captured.
In an article published in October 1946, the Atlanta Constitution cited an unidentified Japanese officer as saying that U.S. air raids on Japan forced the military to move its bomb plant to Japanese-occupied territory in what is now North Korea, delaying Tokyo's bomb development schedule by three months.
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The uranium seized from the German submarine ended up in the American atom bombs, John Lansdale Jr., head of security for the Manhattan Project, said in a 1995 New York Times interview.
Chieko Takeuchi, widow of the atomic scientist, recalled her husband saying, "If we'd built the bomb first, of course we would have used it. I'm glad, in some ways, that our facilities were destroyed."