Molybdenum effects on iodine chemistry during severe accident, 2; Molybdenum-induced iodine revaporization test in a reproduction experimental facility for FP release and transport behavior

Rizaal, M.   ; Nakajima, Kunihisa  ; Miwa, Shuhei  

The interaction of gaseous species with fission product deposits, such as Cs and I, on the surface of reactor coolant system (RCS) materials is considered a contributing factor to the late-phase release of gaseous iodine (revaporization), potentially impacting the containment atmosphere. In this study, the reaction of CsI deposits formed on stainless steel type 304L with molybdenum containing gas flow was investigated. Experiments simulating the RCS temperature gradient within the range of 1050-450 K demonstrated a depletion of CsI deposits previously formed in the temperature range of 950-800 K. This was associated with formation of cesium molybdates on that specific temperature and the release of gaseous iodine that was subsequently trapped at lower temperature locations.