Cesium Chemistry in the LWR severe accident and towards the decommissioning of Fukushima Daiichi Nuclear Power Station

Researches on the fission product chemistry made after severe accident of Fukushima Daiichi Nuclear Power Station were reviewed with focus Cs in terms two regimes, namely, accidental source term and long-term via aqueous phase toward decommissioning. For term, chemical interaction Mo, B, Si under steam atmosphere greatly affect behavior release from fuel revaporization deposit structural material surface reactor coolant system. Regarding unique issue phase, penetration into concrete debris leaching mentioned as main sources FPs. Efforts preparation thermodynamic data for complex oxides described. All these behaviors should be modelled validated/verified through analysis evaluation actual samples including that would taken near future.