JAEA thermodynamic database for performance assessment of geological disposal of high-level and TRU wastes; Selection of thermodynamic data of molybdenum

Kitamura, Akira  ; Kirishima, Akira*; Saito, Takumi*; Shibutani, Sanae*; Tochiyama, Osamu*

Within the scope of the JAEA thermodynamic database project for performance assessment of geological disposal of high-level radioactive and TRU wastes, the selection of the thermodynamic data on the inorganic compounds and complexes of molybdenum were carried out. We focused to select thermodynamic data of aquous species and compounds which could form under repository conditions for the disposal of radioactive wastes, i.e. relatively low concentration of molybdenum and from near neutral through alkaline conditions. Selection of thermodynamic data was based on the guidelines by the Nuclear Energy Agency in the Organisation for Economic Co-operation and Development (OECD/NEA). Extensive literature survey was performed and all the obtained articles have been carefully reviewed to select the thermodynamic data for molybdenum. Thermodynamic data at 25 C and zero ionic strength were determined from accepted thermodynamic data which were considered to be reliable. We especially paid attention to select formation constant of molybdate ion with hydrogen ion.