Difficulties encountered in the japanese performance assessment programme using thermodynamic data

The Japan Nuclear Cycle Development Institute (JNC) published a second progress report (the H12 report) concerning HLW disposal in Japan in November 1999. This report was instrumental in establishing confidence in the concept of a high-level radioactive waste (HLW) disposal system and paved the way for the creation of an implementation body in 2000. JNC developed an in-house thermodynamic database of radioactive elements (JNC-TDB) for the performance analysis of the H-12 report. The database development was focused on the repository condition, reducing and various CO2 conditions. This paper presents the difficulties encountered to increase confidence in JNC-TDB for performance analysis learned from studies undertaken for the H12 report. Those are related to increase reality, reliability and the relevant amount of data under expected repository conditions. (author)