PEER has just published Report No. 2017/11 titled “Preliminary Studies on the Dynamic Response of a Seismically Isolated Prototype Gen-IV Sodium-Cooled Fast Reactor (PGSFR).” It was authored by Benshun Shao, Andreas Schellenberg, Matthew Schoettler, and Stephen Mahin.
The KEPCO Engineering and Construction Company, Inc. (KEPCO E&C) is developing a Prototype Gen-IV Sodium-Cooled Fast Reactor (PGSFR). Preliminary evaluations of the behavior of the isolated PGSFR when subjected to seismic and aircraft impact loading conditions were conducted to support design efforts by KEPCO E&C. Results and key findings of these analyses are as follows: (i) because isolator deformations are typically quite small for the considered seismic excitation levels, the benefit of seismic isolation could be enhanced with revised isolator designs that reduce the apparent yield strength and permit greater displacement demands; (ii) the amplitudes of acceleration and displacement responses resulting from the impact of a large aircraft are similar to or exceed the demands imposed by a seismic event based on the NRC hazard with a peak ground acceleration of 0.3g, and (iii) as provided, the isolator initial stiffness is poorly conditioned since it leads to fundamental isolation frequencies that are not well separated from the plant’s superstructure frequencies, and triggers some resonance that significantly increases floor acceleration response spectra.