Host: The Japan Society of Mechanical Engineers
Name : The 30th International Conference on Nuclear Engineering (ICONE30)
Date : May 21, 2023 - May 26, 2023
Previous work has shown in-core printed circuit heat exchange can provide substantial benefits for molten salt fueled reactors. Reductions in overall salt volume and corrosion/deposition cycles due to loop temperature gradients can be achieved. Excore delayed neutron losses are drastically reduced or eliminated, power density is substantially increased, and hot leg/cold leg corrosion is eliminated along with gaining a nearly flat axial temperature profile across the core. In this analysis, a gas cooled, molten salt fueled core is directly coupled to a Brayton cycle and peak core temperature is tracked over the course of a pump failure transient to determine if safe temperature levels are maintained. An NTU-effectiveness calculation is coupled with a point kinetics model as well as feedback to coolant flow rate and heat exchange to model the overall behavior of the system over time. These feedbacks are used to estimate the power and temperature response for a molten salt reactor at steady state and during a primary flow loss transient. Peak temperature conditions are of particular interest in the transient case to determine if the temperature feedback response is sufficient to prevent the system from achieving high temperatures that are incompatible with standard structural materials such as SS-316H or nickel/molybdenum alloys such as Hastelloy-N. While the strongly negative temperature reactivity coefficients inherent to molten salt fuels aid in preventing high temperatures, the passive nature of the coolant flow through the power cycle allows for excellent safety performance in the event of loss of off-site power accidents or pump failures. Safe temperatures can be maintained in an accident scenario, and as much as a third of nameplate electrical power can continue to be produced during a primary pump failure or loss of offsite power accident. The concept promises not only to be “walk-away-safe” but to be a resilient source of power production in the face of accident conditions. This may offer advantages in terms of grid stability in unforeseen circumstances.
