As a part of safety assessment, fission product (FP) behavior along with specific accident scenarios has been focused on, not only in the licensing preparation stage but also in the design process of advanced reactors, especially to provide and present its robust safety architecture to achieve higher safety level than the current reactor fleets. It has been pointed out for sodium-cooled fast reactor that most of the FP, which are potentially released from fuel pins under design basis accident and design extension condition, will remain in its reactor primary coolant system because sodium as an alkali metal chemically reacts with iodine as a halogen into a solid-state stable salt (i.e. NaI). Sodium coolant easily dissolves cesium also as an alkali metal and other metallic FP elements under typical operational and accident conditions where sodium does not boil due to its high boiling point under atmospheric pressure. To quantify the migration behavior of FP after being released from fuel pins due to failures or breaches, it is essential to accumulate experimental knowledge for improving physical, chemical, and fluid dynamics models in combination with FP-containing gas bubble behavior known as so-called “scrubbing” of non-condensable gaseous FPs of xenon and krypton. JAEA has developed a mechanistic source term analysis code, TRACER, for assessing such FP behavior in the primary coolant system of sodium-cooled fast reactor. This report introduces aerosol behavior models newly incorporated into the TRACER code and presents the results of a benchmark analysis on in-sodium experiments of gas bubbles containing simulated aerosol materials.
Okano et al. (Wed,) studied this question.