Construction of Microbial Kinetics Database for PA of HLW disposal
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Construction of Microbial Kinetics Database for PA of HLW disposal Hideki Yoshikawa1, Tsuyoshi Ito2, Kotaro Ise1 and Yoshito Sasaki1 1 Geological Isolation Research and Development Directorate, Japan Atomic Energy Agency 4-33, Muramatsu, Tokai-mura, Naka-gun, Ibaraki 319-1194, Japan. 2 Visible Information Center Inc., Tokai-mura, Naka-gun, Ibaraki 319-1112, Japan ABSTRACT To evaluate a change of chemical species of groundwater composition by the metabolism of microbes, which will be introduced to deep underground from the surface and be in a deep underground, is important for the discussion of the microbial effects on the performance assessment of the high-level radioactive waste repository. The purpose of this study is to develop of a microbial kinetics database to evaluate their activities in the deep underground environment. Some microbial metabolism data were collected and constructed their kinetics database for aerobic, denitrifying, manganese reducing, iron reducing, sulfate reducing, methanogenic and acetogenic bacteria to evaluate above groundwater chemistry. About 1260 data were selected by literature survey for some journals and books published from 1960s and summarized in this microbial kinetics database. Some sensitivity analyses were performed for some parameter of metabolism of microbes. INTRODUCTION The microbial effect on groundwater evolution present as an important issue in safety assessment of geological disposal of high-level radioactive waste (HLW). For example, some microbes consume dissolved oxygen, change chemical species from NO3- to N2, and reduce charge valence of iron or manganese from oxidizing to reducing condition in groundwater. The authors have been investigating the microbial growth rate of each microbe metabolism group in order to predict the quantitative evaluation of microbial activity affect on the groundwater component, and developing an evaluation method by using PHREEQC code to calculate the chemical composition in groundwater under the microbial effect. The microbial growth rate is represented generally by the Monod equation which is empiric formula. Value of the each parameter of the Monod equation varies due to differences microorganism type, growing environment, and the metabolic reaction. In addition, there is little information about the microbial activity present in the deep geological environment, such as their detail metabolism and death. Previous paper has shown that the microbial activity parameters related to the rate equation for microbe metabolisms and death from existing literature, and were collected and a microbial kinetic parameter database was constructed [1]. In this paper, moreover, a sensitivity analysis of each parameter and the comparison of their values for each parameter were performed for aerobes. A proposal to set the appropriate parameters to calculate the microbial activity are described in this paper for the potential use of the database for geological disposal.
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STRUCTURE OF MICROBIAL PARAMETER DATABASE Some calculation example of microbia
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