Study on the coupling effects between reactor coolant system and the internal structure on floor response spectrum of small modular reactor

Abstract

AbstractAccording to Chinese code and US standard review plan (US SRP), when the equipment and structure satisfy certain decoupling conditions, the seismic analysis of the structure is performed using a decoupling method, where only the mass of the equipment is considered in the structure. The reactor coolant system of small modular reactor (SMR) which is integrated is different from that of PWR, and it is more likely to affect the seismic response of the supporting structure. In this paper, a decoupling model was first constructed based on the decoupling principles in the code. Then, a coupled model is built by connecting the main loop system model with the structure. The floor response spectra of the decoupling model and the coupled model are analyzed separately using ACS SASSI software to investigate the coupling effect. By the comparison of the results, the preliminary conclusions are drawn as follows: the decoupling criteria in code are met for the internal structure and reactor coolant system. For hard rock site, the coupling effect has negligible influence on the in‐structure response spectra (ISRS) for most of the structure except the reactor pit, which shows obvious change in the high‐frequency region. For soft soil site, there is no remarkable influence on the ISRS of the structure even for the reactor pit due to the filter effect of the site to the high‐frequency component in the seismic input. For the site with shear wave velocity greater than 1100 m/s, the influence of couple effect cannot be ignored.