The Japanese program to develop nuclear weapons was conducted during World War II. Like the German nuclear weapons program, it suffered from an array of problems, and was ultimately unable to progress beyond the laboratory stage before the atomic bombings of Hiroshima and Nagasaki and the Japanese surrender in August 1945.
Today, Japan's nuclear energy infrastructure makes it capable of constructing nuclear weapons at will. The de-militarization of Japan and the protection of the United States' nuclear umbrella have led to a strong policy of non-weaponization of nuclear technology, but in the face of nuclear weapons testing by North Korea, some politicians and former military officials in Japan are calling for a reversal of this policy.
In 1934, Tohoku University professor Hikosaka Tadayoshi's "atomic physics theory" was released. Hikosaka pointed out the huge energy contained by nuclei and the possibility that both nuclear power generation and weapons could be created. In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to Naturwissenschaften reporting that they had detected the element barium after bombarding uranium with neutrons; simultaneously, they communicated these results to Lise Meitner. Meitner, and her nephew Otto Robert Frisch, correctly interpreted these results as being nuclear fission and Frisch confirmed this experimentally on 13 January 1939. Physicists around the world immediately realized that chain reactions could be produced and notified their governments of the possibility of developing nuclear weapons.
The leading figure in the Japanese atomic program was Yoshio Nishina, a close associate of Niels Bohr and a contemporary of Albert Einstein. Nishina had co-authored the Klein–Nishina formula. Nishina had established his own Nuclear Research Laboratory to study high-energy physics in 1931 at RIKEN Institute (the Institute for Physical and Chemical Research), which had been established in 1917 in Tokyo to promote basic research.
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On 6 and 9 August 1945, the United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki. The bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the only use of nuclear weapons in an armed conflict. Japan surrendered to the Allies on 15 August, six days after the bombing of Nagasaki and the Soviet Union's declaration of war against Japan and invasion of Japanese-occupied Manchuria. The Japanese government signed the instrument of surrender on 2 September, effectively ending the war.
The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, bringing the war's hostilities to a close. By the end of July 1945, the Imperial Japanese Navy (IJN) had become incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of the Japanese armed forces in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction".
Substantial debate exists over the ethical, legal, and military aspects of the atomic bombings of Hiroshima and Nagasaki on 6 August and 9 August 1945 at the close of World War II (1939–45). On 26 July 1945, United States President Harry S. Truman, British Prime Minister Winston Churchill and President of China Chiang Kai-shek issued the Potsdam Declaration, which outlined the terms of surrender for the Empire of Japan as agreed upon at the Potsdam Conference.
The Japan Atomic Energy Agency (JAEA) developed ITER TF Nb3Sn conductors that fulfill ITER requirements and has commenced fabricating the conductors to be used in the ITER TF coils. As a qualification of conductor fabrication, two full-size conductor sampl ...
Japan Atomic Energy Agency (JAEA) has fabricated and tested the four conductor samples composed of high performance strands manufactured by the bronze-route process for the ITER Central Solenoid (CS) conductor. The current sharing temperature (Tcs) electri ...
Japan Atomic Energy Agency (JAEA) is procuring 100% of the ITER Central Solenoid (CS) conductors. The CS conductor is required to maintain the performance under 60000 pulsed electromagnetic cycles. JAEA tested two internal-tin Nb3Sn conductors for the CS a ...