The water cooled lithium lead breeding blanket (BB) stands out as one of the most promising designs for future fusion reactor BBs. However, the significant interaction between water and lithium–lead, particularly triggered by an In-Box LOCA (Loss of Coolant Accident), presents a critical safety concern. This concern has spurred the scientific community to develop a sophisticated numerical analysis tool capable of simulating such a complex interaction. The SIMMER code family from Japan Atomic Energy Agency has emerged as the most suitable tool for conducting safety analysis evaluations to aid in the design of the WCLL-BB at a system level. Extensive efforts have been devoted in recent years to enhancing the accuracy of simulations for such accidents. Specifically, the SIMMER code was modified by UNIPI to accurately model the chemical interaction between water and lithium–lead. However, further refinement of the chemical model is deemed necessary for an accurate representation of the interaction between these two fluids. This refinement involves modeling lithium–lead as a liquid alloy and monitoring the concentration of the chemically active element, namely lithium. The modification has been implemented using a feature of SIMMER capable of distinguishing between Fertile and Fissile components of liquid fuel. Moreover, an initial endeavor to introduce a chemical reaction kinetic rate controlled by diffusion has been undertaken within SIMMER, drawing on the analogy between Heat Transfer and Mass Transfer. This work shows the verification of the new chemical model against the stoichiometry and the results of a SIMMER-III simulation using the new implemented diffusion model, highlighting the importance of developing the chemical kinetic for the safety evaluation of an In-Box LOCA.
Progress towards the validation of SIMMER-III code model for lead-lithium water chemical interaction