Enhancing safety in molten salt reactors; Understanding how design choices affect freeze plug performance

Muhammad, I.; Indarta, A.*; Okawa, Tomio*

In molten salt reactors (MSRs), a critical safety mechanism is the freeze plug. This research aims to investigate the effects of fundamental design parameters on the complete freeze plug process, which include solidification, melting, and draining. A thicker and larger tube has longer solidification time, but has a shorter melting and draining (opening) time. Conversely, a thinner and smaller tube solidify faster but takes longer to open, indicating trade-off in selecting an efficient design. Also, an inclined tube with a novel jacket and conical design accelerates the melting process with small impact on solidification, therefore enhancing its performance. This research expected to provide useful recommendations and guidelines for designing efficient yet reliable freeze plugs in MSRs.