Structural integrity assessment of reactor assembly components of a pool-type sodium fast reactor in a core disruptive accident - II: Analysis for a 500-MW(electric) prototype fast breeder reactor

Abstract

A core disruptive accident, considered a beyond-design-basis accident, for the 500-MW(electric) capacity Prototype Fast Breeder Reactor (PFBR) is analyzed using the FUSTIN in-house computer code. In order to have a good understanding of the complicated loading mechanisms and sequences, the analysis studies the effects of introducing internals in the main vessel. Further, the structural integrity of heat exchangers - which are important for decay heat removal during postaccident conditions - was demonstrated with tests that were conducted on a 1/13th scaled-down mock-up; a suitable low-density explosive was developed and characterized to simulate nuclear energy release characteristics. The tests have indicated relatively smaller displacements and strains in the vessel, compared to numerical predictions, and the structural integrity of the decay heat exchangers including tubes was demonstrated. Thus, the reactor assembly components meet the safety criteria specified for PFBR with comfortable margins for the specified mechanical energy release of 100 MJ.