Dynamic analysis of a primary reactor coolant system subjected to seismic and LOCA loads, including shield building interaction

Abstract

This paper is intended to describe the development of a unique method of analysis for a primary reactor coolant piping system to evaluate its adequacy and the need for structural support system optimisation under hypothetical seismic and loss-of-coolant-accident loading conditions. An integrated approach is presented for a linear three-dimensional dynamic analysis of a typical 900 MWe PWR nuclear reactor coolant loop, accommodating dynamic coupling and interaction effects of shield building, including soil-foundation springs and damping parameters. Also included are major influences on sensitive equipment due to their variable support boundary conditions and rigid restraints. Due to the vital nature of reactor coolant systems, important dynamic design criteria have to be established in order to estimate natural frequencies, damping characteristics and overall system behaviour during LOCA and strong motion earthquakes as well as to optimise the structural design of various components.