Effects of temperature on deposition rate of supersaturated silicic acid on CA-type bentonite

Tsuyoshi Sasagawa, Taiji Chida, Yuichi Niibori

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

For the disposal system of high-level radioactive waste in Japan, Na-type bentonite is used as one of backfilling and buffer materials for preventing the migration of groundwater and radionuclide. However, the alteration to Ca-type bentonite will cause the degradation of the barrier performance. On the other hand, silicate minerals around the repository dissolve under the high alkaline condition of groundwater (about pH 13) altered by alkaline components leaching from cementitious materials used for the construction of the repository. Such high-concentration silicic acid becomes supersaturated with the decrease in pH by mixing with natural downstream groundwater (pH 8) because of the change in the solubility of silicic acid. So far, the authors have examined the deposition rates of supersaturated silicic acid on Ca-type bentonite under the condition of room temperature, showing the clogging effect of flow-paths with the deposition. However, the dynamic behaviors of silicic acid are much sensitive to temperature change. Therefore, the present study focuses on the effect of temperature on the deposition rate of silicic acid on Ca-type bentonite. As a result, in the range up to 323 K, the deposition of supersaturated silicic acid on Ca-type bentonite was promoted with the increase in temperature. This suggests that the deposition of silicic acid will clog the flow-paths in Ca-type bentonite in this temperature range.

Original languageEnglish
Title of host publicationStudent Paper Competition
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791850053
DOIs
Publication statusPublished - 2016
Event2016 24th International Conference on Nuclear Engineering, ICONE 2016 - Charlotte, United States
Duration: 2016 Jun 262016 Jun 30

Publication series

NameInternational Conference on Nuclear Engineering, Proceedings, ICONE
Volume5

Other

Other2016 24th International Conference on Nuclear Engineering, ICONE 2016
CountryUnited States
CityCharlotte
Period16/6/2616/6/30

ASJC Scopus subject areas

  • Nuclear Energy and Engineering

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