SEISMIC ASSESSMENT OF CROSSOVER PIPING ON A SODIUM COOLED FAST REACTOR WITH THREE-DIMENSIONAL ISOLATION SYSTEM

A three-dimensional seismic isolation system is planed for application to the conceptual design of a sodium-cooled fast reactor in Japan. The main steam crossover piping is laid between the nuclear building with the isolation system and the turbine building without the isolation system. A large displacement of the nuclear building with the isolation system is imposed on the crossover piping, which situation is a particular seismic issue because of the isolation system employment. Furthermore, because the SFR operates at elevated temperatures compared with light water reactors, the crossover steam piping design must comply with the design code for elevated temperature components. In this study, seismic evaluation using an example of a crossover piping layout was performed in accordance with the elevated temperature code of Japan Society of Mechanical Engineers. According to the evaluation results and the up to date technologies such as knowledge obtained from existing dynamic failure tests of piping components, an appropriate seismic evaluation method for the crossover piping was studied to realize the sodium- cooled fast reactor with a three-dimensional isolation system.