Thermal-hydraulic Analysis of the Upper Plenum of a SFR
Thermal-striping phenomenon is a potential safety concern in the long term operation of a Sodium Fast Reactor (SFR) due to the thermal stresses accumulated on structures and components from the impingement of poorly mixed streams of coolant flow from different sub-assemblies. Incomplete mixing out of the core has an impact on the thermal-hydraulic performance and design of both loop- and pool-type SFRs. Here, the mixing phenomenon has been numerically investigated using a Reynolds Average Navier Stokes (RANS) equation model available in commercial CFD package (COMSOL).
The design of the upper plenum against thermal striping phenomena was numerically guided using a bottom-up scaling approach with a dual-jet model. A two-jet mixing experiment for sodium has been built, but testing to date has been with water. Based on current CFD and preliminary experimental results, a correlation has been developed using variation of scales (length, energy, number, distribution, and time) to guide our understanding of nonlinear single phase thermal-hydraulics. Descriptive samples of results to date and associated efforts in the research group will be given.