Seismicity and seismic response of the Soviet-designed VVER reactor plants

On March 4, 1977, a strong earthquake occurred at Vrancea, Romania, about 350 km from the Kozloduy plant in Bulgaria. Subsequent to this event, construction of the unit 2 of the Armenia plant was delayed over two years while seismic features were added. On December 7, 1988, another strong earthquake struck northwest Armenia about 90 km north of the Armenia plant. Extensive damage of residential and industrial facilities occurred in the vicinity of the epicenter. The earthquake did not damage the Armenia plant. Following this event, the Soviet government announced that the plant would be shutdown permanently by March 18, 1989, and the station converted to a fossil-fire plant. This paper presents the results of the seismic analyses of the VVER (water-cooled, water-moderated energy reactor) plants. Also presented is information concerning seismicity in the regions where VVERs are located and information on seismic design of VVERs