Laboratory and in-situ examinations of microbial abundance, composition and activity in compacted bentonite buffer materials

圧縮ベントナイト緩衝材における微生物現存量, 種組成および活性についての室内試験および原位置試験

天野 由記   ; 別部 光里*; 大野 宏和 ; 谷口 直樹 ; 平野 伸一*; 松本 伯夫*; 長岡 亨*

Amano, Yuki; Beppu, Hikari*; Ono, Hirokazu; Taniguchi, Naoki; Hirano, Shinichi*; Matsumoto, Norio*; Nagaoka, Toru*

Microbial activity in bentonite buffer materials in deep geological repository is of concern for microbiologically influenced corrosion which could affect the longevity of metallic containers. Data has been collected regarding microbial corrosion of carbon steel or cupper using compacted bentonite. However, there is not enough data collected under Japanese geological disposal concept, using Kunigel V1 and silicate sand. To evaluate microbial effects on corrosion of metallic containers and activity in bentonite buffer materials with Kunigel V1, we have conducted laboratory-scale and in-situ experiments. From the result of the experiments, it is demonstrated that a sufficiently high dry density is one of the important key factors to suppress microbial activity in buffer materials surrounding metal containers, because of the physical characteristics such as small pores, low water activity, less nutrient supply caused by low hydraulic conductivity. However, microbial cells were heterogeneously detected in the bentonite buffer materials of in-situ experiment. This seems to result from nonuniformity in dry density, water content, and swelling pressure etc., in the engineering scale experiment. These results also demonstrate that the heterogeneous repository conditions would be possibly occurred.