Economic Rationality and International Humanitarianism: Ryōkichi Sagane's Advocacy Regarding the Introduction of Foreign Nuclear Reactors to Japan**

The 2011 Fukushima Daiichi Nuclear Power Plant accident underscored the crucial role of nuclear engineering experts. However, the specific arguments and motivations of scientists advocating for the introduction of foreign reactors remain unclear. This study delves into the contribution of Ryōkichi Sagane (1905-1969), a prominent figure during their introduction, and analyzes the specifics of his arguments for the importation of reactors examining his motivations and background. Sagane, who studied nuclear physics in the U.S., gained expertise in nuclear experiments and became acquainted with American scientists. In the late 1950s, with the period of Japan's adoption of nuclear power, he understood the arguments of foreign and domestic experts and disseminated this information to the public. His claims for importation of reactors rested predominantly on the ground of economic and managerial rationality. Beyond mere rationalism, Sagane's drive for reactor introduction was rooted in international humanitarianism based on personal friendships that transcended national borders. The rhetoric of promoting nuclear power for the sake of humanity resonated with the nuclear energy policy of the U.S. during the early Cold War. However, unlike the motivation of the U.S. to suppress opposition to the development of nuclear weapons, Sagane's motivation arose from his scientific practice.