Methodology Development and Determination of Solubility-limiting Solid Phases for a Performance Assessment of Geological Disposal of High-level Radioactive and TRU Wastes

• Published in: Journal of Nuclear Fuel Cycle and Environment Vol. 27; no. 2; pp. 58 - 71
• Main Authors: GOTO, Takahiro, SHIBUTANI, Sanae, YOSHIDA, Yasushi, KITAMURA, Akira
• Format: Journal Article
• Language: English
• Published: Division of Nuclear Fuel Cycle and Environment, Atomic Energy Society of Japan 15.12.2020
• Subjects: geological disposal; high-level radioactive waste; solubility; solubility-limiting solid phase; thermodynamic database; TRU waste
• ISSN: 1884-7579; 1884-7579
• DOI: 10.3327/jnuce.27.2_58

  Evaluation and estimation of solubility values are required for a performance assessment of geological disposal of high-level radioactive and TRU wastes. Selection of solubility-limiting solid phases (SSPs) that control the solubility of radionuclides is necessary for the evaluation and estimation of solubility values. The authors have developed a methodology for selection of the SSP through a calculation of saturation indices (SIs) using thermodynamic database to show a transparent procedure for the selection. Literature survey has been performed to confirm decision of the SSP from candidate SSPs which generally have larger SIs from realistic point of view for precipitation and solubility control. The authors have selected the SSPs for the elements of interest for the latest Japanese performance assessment in bentonite and cement porewaters after grouping various water compositions.