Development of a statistical evaluation method for core hot spot temperature in sodium-cooled fast reactor under natural circulation conditions

摘要

To enhance the safety of a sodium-cooled fast reactor (SFR), natural circulation must be able to remove the decay heat in the core, even if the AC power supply to the forced circulation equipment is lost. Under natural circulation conditions, deterministically evaluating the core hotspot temperature considering the effects of un-certainty on the sodium flow and heat is difficult because the flow is driven by buoyancy, and the flow rate and the temperature distribution influence each other. This study develops a statistical evaluation method for the core hot spot temperature by propagating the uncertainty through the input of the analysis to the output using the Monte Carlo sampling method. The core hot spot evaluation method is applied to three representative events during the natural circulation decay heat removal operations in a loop-type SFR.