In modern times, the use of nuclear energy and radiation are inseparable. The size of two wheels can be measured and compared by the term economic scale, which in this case refers to the revenue of electricity at terminal and production costs associated with radiation applications at a factory. The magnitude ofnuclear(nuclear energy+radiation) between Japan and the United States of America (the U.S. or U.S.A.) was hereinafter compared for the year 1997. Results obtained are: (1) The economic scale of nuclear use in the U.S. was 158b$ (billion dollars), 119b$ (75%) of which was attributed to radiation applications with a further 39b$ (25%) due to nuclear energy. In the case of Japan, the total of 99b$ was composed of 52b$ (53%) radiation with a further 47b$ (47%) on nuclear energy. (2) The economic scale fornuclearuse in the U.S. is larger than that of Japan by a factor of 1.6, due primarily to its larger economic scale of industry and medicine. The economic scale of nuclear energy in the U.S. is relatively smaller than that for Japan. The U.S. as opposed to Japan, which depends highly on nuclear energy, depends more highly on the use of coals for power generation. This in itself is the main reason for the smaller economic scale of nuclear energy in the U.S.
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