Abstract
At first in this review, a brief history from the discovery of nuclear fission to the development of nuclear reactors is given. And then, nuclear fission and neutron capture reactions which occur in nuclear reactors are explained by stressing on nuclear transformations. The structure of nuclear power reactors, mainly pressurized water reactors(PWR)is briefly described. In the main part of this review, advantageous points in nuclear power for electric production are demonstrated. And then, several dangerous points in nuclear power are shown by a table and countermeasures against them are also given. Thereafter, the safety and the reliability of nuclear power reactors are defined and research activities how to improve them are explained. In the last part, introduced are several examples of related research works being carried out at the Institute of Nuclear Safety System, Inc. (INSS)as follows:(1)Recent activities of collecting and analyzing adverse events occurred in nuclear power plants in the world and of giving related proposals for improvement to all electric power companies in Japan, which possess PWRs. (2)Framework of research activities for countermeasures against ageing of nuclear power plants. (3)Two examples of measured results, atomic mappings of impurity elements in a specimen of reactor vessel steel after neutron irradiation and at a tip of stress corrosion crack in stainless steel which is mainly used for the main part of the primary water system of PWR. Both microscopic analyses are performed to elucidate the mechanisms of neutron irradiation embrittlement and stress corrosion cracking. (4)Analysis of severe accidents of PWR plants for the preparedness of nuclear disasters. Application of the calculated results to the exercise of nuclear disasters.
