The February 6, 2023 Magnitude 7.8-7.5 earthquake in Turkey with the peak ground acceleration (PGA) close to 1.0g has shown and confirm a general efficiency of base seismic isolation (BI) for protection of buildings and structures against seismic motion. However, the information regarding behaviour of the seismic isolated structures subjected to PGA over 0.5 g is quite limited. The Akkuyu NPP, which is in the final construction phase and is located not so far from the epicentre, was also shaken by this earthquake, but without consequences due to PGA lower 0.05g.

At the same time recent investigations during Tohoku Earthquake 2011 and at the world’s biggest E-Defence 1500 tons shaking table in Japan have demonstrated inconsistent results for conventional isolation systems with an essential seismic amplification in the vertical direction and limited overall efficiency.

This contribution presents results of analysis, natural scale testing and application of the first of such a kind passive Base Control System (BCS) consists of the spatial (3D) coil spring isolators and separately located 3D viscodampers. The efficiency of the BCS system were confirmed by a comparative analytical study, natural scale testing and behaviour under real earthquake.