Thermalhydraulics analysts at CNL are once again demonstrating the value of Canada’s national nuclear laboratory with their first-of-a-kind efforts in advanced thermalhydraulics modelling for novel SMR concepts. The team is using advanced coupled computer simulations to gain detailed insights into the fluid flow and heat transfer characteristics of both microreactor and grid-scale SMRs to support their safety and performance. Their work has been instrumental in developing three-dimensional multiphysics modelling capabilities and advanced computational codes that are capable of accounting for thermalhydraulics and neutronics feedback in accident scenarios. Most recently, they successfully validated measurements attained from an integral test facility (an experimental set-up) of a scaled prismatic gas-cooled reactor concept, demonstrating greater accuracy in modelling reactor safety scenarios.
“While size and modularity contribute to the popularity of SMRs, these novel designs present scientists with some technical challenges,” says Dr. Krishna Podila, Thermalhydraulics Analyst, CNL. “One of the primary ones is ensuring computational tools and methods can be reliably used to meet design and safety objectives under accident scenarios. We’re dealing with compact, highly integrated systems with many of the concepts proposed for deployment – requiring much more computationally intensive simulation to model the multiple interacting physical processes happening simultaneously.”
The team’s development of such advanced computational code is part of Atomic Energy of Canada Limited’s Federal Nuclear Science & Technology Work Plan – the ongoing project, “Development of an innovative approach for modelling and simulation of advanced micro-reactors for safety and licensing”. As part of this particular project, they successfully paired three-dimensional computational fluid dynamics code: Siemens STAR-CCM+ with CNL’s one dimensional system thermalhydraulics code: ARIANT to execute coupled thermalhydraulics analyses. And they did this by leveraging CNL’s in-house high-performance computing facility (ATHENA), overcoming several challenges related to solution stability (the reliability of the codes) and accuracy crucial for the application of coupled simulations in optimizing design of current and next generation reactors.
“The deployment of SMRs will eventually require safety and licensing analyses, and this current work takes us that much closer to developing the reactor safety codes that can be used to better understand key phenomena and guide experiments,” says Podila. “It’s very exciting to be chartering Canada’s footprint globally in thermalhydraulics modelling of next generation reactors.”
Through the execution of these first-of-a-kind efforts, CNL has been able to increase its visibility amongst other national laboratory counterparts and experts in the field of thermalhydraulics. It’s also led to Canada’s participation as a full member in the Generation-IV Forum (GIF) Very High Temperature Computational Methods and Validation Benchmark (CMVB). GIF is an international cooperative focused on developing the research necessary to test the feasibility and performance of fourth generation nuclear systems, which includes SMRs.
As a next step, the thermalhydraulics team will be testing the coupled modelling code suite for problems that are ranked high in importance for reactor safety under an international thermalhydraulics benchmark that was co-organized by CNL and other leading international nuclear laboratories under the Organization for Economic Cooperation and Development/Nuclear Energy Agency.
