News Navigator: Did Japan also conduct research to create atomic weapons?

The Mainichi Shimbun answers some common questions readers may have about whether Japan ever had a nuclear research program.

Question: I watched the film “Oppenheimer,” which won seven Academy Awards. Did Japan also conduct research into building atomic weapons?

Answer: Although far from having reached the production stage, a renowned physicist has conducted research to create atomic weapons in great secrecy. In 1938, German scientists announced the fission of the atom. It was learned that by impacting uranium atoms with neutrons, the atomic nucleus is torn away and a chain reaction produces enormous amounts of energy. The following year, Nazi Germany invaded Poland, starting World War II. The United States and Britain began researching atomic weapons out of fear that the Nazis would develop a new form of weapon, and Japan also began military-related research.

Q: Who participated in the research?

A: The Imperial Army brought in Yoshio Nishina, known as the “father of modern physics in Japan,” to Riken, which is now Japan's largest scientific research institute. The “Ni-go” research program was partly named in his honor. At the same time, the Imperial Navy sought help from Professor Bunsaku Arakatsu of Kyoto Imperial University (now Kyoto University) and others, calling their program “F research,” the “F” standing for “fission,” or splitting of the atomic nucleus. Hideki Yukawa, Japan's first Nobel Prize winner, also worked on this research.

Q: Why did it fail?

A: The main reason was the lack of uranium ore. Natural uranium contains only about 0.7% of the isotope 235, uranium that can be easily cracked. It appears that researchers have failed to develop the technology needed to enrich the substance. During this time, the United States used this technology to drop atomic bombs and devastate the cities of Hiroshima and Nagasaki. After the war, Yukawa became involved in anti-nuclear and pro-peace activism.

(Japanese original by Tomohiro Ikeda, Lifestyle News, Science and Environment Department)