Anti-Earthquake Design of Industrial Facilities

In Japan two sets of guidelines pertaining to modern aseismic design are being prepared. One is the guideline for the aseismic design of petrochemical plants and oil refineries, and the other is the code of aseismic design of nuclear power plants. The International Atomic Energy Agency also established its own guideline very recently. Several other countries also provide their own codes or guidelines. Among these, the regulatory guides of the United States are well known and quoted often; however some of them seem to be too sophisticated, for example, the three dimensional input problem. The reason for this is that the requirement of safety for a nuclear power plant is so severe that all events which have even a very low probability of occurrence should be considered. Therefore, if the results of theoretical study indicate an event which may occur even in very low probability, then from the viewpoint of conservatism, the designer must consider that event in this design. Although for the design of a nuclear power plant this might be partly true, the author feels that the probability of occurrence of the event should be evaluated in relation to the potential hazard of the design object. As well as this, he believes that proper understanding of the event in relation to the actual record of failures during past destructive earthquakes should be taken into consideration.