Safety, ease-of-mind, and safety based on risks

The concept of 'safety' is wide-ranging, and its meaning is different depending on the field, and historically the concept of 'safety' has changed. First, this paper gives a general definition of the words 'safety' and 'ease-of-mind.' 'Ease-of-mind' is a subjective emotion, and varies greatly depending on what kind of information it is based on. When considering 'ease-of-mind/safety' and 'anxiety/danger,' there are four combinations of areas, and the area of combination of danger/anxiety become a major problem. In the case of nuclear power plants, they belong to the area where anxiety is felt even though they are basically safe. Let us think about what causes anxiety, why our anxiety does not disappear, and how our anxiety diminishes. Next, this paper discusses what the safety based on risks is, and describes risk analysis, preventive measures related to risk analysis, and measures at the time of risk occurrence (mitigation measures). In addition, it shows the results of applying the risk analysis process to the structural problems of pressure facilities, and describes the probability of structural failure. (A.O.)