Development of seismic analysis method of fast reactor core

Abstract

To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Sophisticated analysis method has been developed to study the seismic response of FR core. The fast reactors consist of several hundred core assemblies which are hexagonal flexible beams embedded at the lower support plate in hexagonal arrangement, separated by small gaps, and immersed in a fluid. Core assemblies have no support for fixing to avoid the influence of thermal expansion and swelling. So a nonlinear analytical model needs to contain the collision and the friction between adjacent core assemblies and the fluid-structure interaction in horizontal direction, and behavior of raising from the lower support plate in vertical direction. If a big earthquake occurs, large displacement and impact force of each core assembly may cause a trouble in control rod insertability and core assembly strength. Therefore, it is very important to understand the behavior of core assemblies. This paper summarizes the details of the core assembly vibration analysis code in three dimensions (REVIAN-3D) to calculate three dimensional displacement and impact force of core assemblies.