Sodium cooled Fast Reactors (SFRs) are built with several engineered safety features to prevent and mitigate core melt accidents. Core catcher is a passive mitigation device, which enables retention of core debris resulting from hypothetical core melt accidents in a subcritical and coolable geometry. The core catcher of Prototype Fast Breeder Reactor (PFBR) uses Austenitic Stainless Steel (ASS) as structural material. Future designs shall consider large thermal loads resulting from melting of whole core in the view of enhanced safety requirements. Provision of suitable refractory material&nbsp;as protection layer for Austenitic Stainless Steel made core catcher plate can be one of the promising option to enhance the melt retention capability. However, thermal stability of protective layer in presence of high temperature sodium and during impact of high temperature molten corium is to be ensured for its satisfactory performance. Based on preliminary studies, sintered magnesia has been chosen as candidate material and experiments were carried out to investigate its stability in liquid sodium. Accelerated sodium compatibility tests were carried out at 850 oC by exposing magnesia specimens in sodium for 240 h. Tests were also carried out to assess its corium load withstanding capability in sodium at 850 oC under mechanical loading. Sodium exposed magnesia specimens were subjected to XRD and SEM analysis to assess material degradation. The experimental results are discussed in the paper.

Investigation on Thermal Stability of Sintered Magnesia in Sodium for Core Catcher Application in SFRs

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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