Active seismic response control systems for nuclear power plant facilities

The original concept of an “Active Seismic Response Control System” has been presented by the first author in the latter half of the 1950’s, when the nuclear power plants were just going to be adopted into Japan. While the earthquake-resistant approach to them, in the field of civil engineering, had still important problems then, the first author(1957) proposed several kinds of the supporting systems for the reactor and the steam generater. These ideas were deduced from his investigations on the non-linear vibration theory in which the characteristics of the non-linear hardening restoring force emphasized the efficiency for suppressing the nonstationary resonant responses of structures. In consequence of the theoretical and analytical researches, the four principles were proposed (Kobori 1960); P1 cut off the seismic energy transmission source, if possible. p2 use an energy absorption mechanism. p3 isolate the natural frequencies of a controlled structure against the dominant frequencies of seismic disturbance as possible. P4 control a structure to cause nonstationary and unresonant states by applying its variable non-linear property actively.