JAEA's R&D on the thermochemical hydrogen production IS process

Kasahara, Seiji  ; Tanaka, Nobuyuki ; Noguchi, Hiroki  ; Iwatsuki, Jin ; Takegami, Hiroaki ; Yan, X. ; Kubo, Shinji  

Japan Atomic Energy Agency (JAEA) has studied iodine-sulfur (IS) process, a thermochemical cycle to produce hydrogen by water splitting. This process is a candidate application of high temperature heat from high temperature gas-cooled reactors (HTGRs). This paper outlines the IS process study in JAEA, in particular recent situation of the R&D. Reactor components and a total process facility are tested to evaluate their integrity. A Bunsen reactor, a HSO decomposer and a HI decomposer made of industrial materials have been examined separately as reactor components. A semi-batch test and a thermal cycle test were operated in the Bunsen reactor. HSO decomposition test is in a bayonet type reactor and HI decomposition test in an adiabatic radial flow type reactor are now under way. An experimental apparatus of the total IS process has just been constructed to verify integrity of process components and continuous hydrogen production. Electro-electrodialysis (EED) cells to concentrate HI before distillation is applied in the facility. Performance data of EED cells has been collected aiming to estimate H production thermal efficiency. Influence of temperature, composition in solution and existence of impurities on the cell properties has been investigated. Reduction of heat input to HI separation step by applying the results of the study was shown by a process flow simulation.