Migration behavior of potassium and rubidium in compacted bentonite under reducing condition with iron corrosion product

Kazuya Idemitsu, Hirotomo Ikeuchi, Daisuke Akiyama, Yaohiro Inagaki, Tatsumi Arima

研究成果: Chapter in Book/Report/Conference proceedingConference contribution

抄録

Carbon steel overpack will corrode by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. The iron corrosion products can migrate in bentonite as ferrous ion through the interlayer of montmorillonite replacing exchangeable sodium ions in the interlayer. This replacement of sodium with ferrous ion may affect the migration behavior in the altered bentonite not only for redox-sensitive elements but also the other ions. Therefore the authors have carried out electromigration experiments of potassium or rubidium with source of iron ions supplied by anode corrosion of iron coupon in compacted bentonite. Five to fifteen micro liter of tracer solution containing 3.3 M of KCl or 2.2 M of RbCl was spiked on the interface between an iron coupon and bentonite, which dry density was around 1.4 Mg/m 3, before assembling. The iron coupon was connected as the working electrode to the potentiostat and was held at a constant supplied potential between - 600 and 300 mV vs. Ag/AgCl reference electrode for up to 8 days. Potassium could migrate faster and deeper in bentonite specimen than iron in each condition. On the other hand rubidium could migrate slower than iron. Migration velocity was a function of applied electrical potential and 8 to 14 nm/s for potassium, 5 to 10 nm/s for iron and 3 to 5 for rubidium, respectively. Dispersion coefficient was also a function of applied potential and 10 to 14 × 10-12 m2/s for potassium, 4 to 8 × 10 -12 m2/s for rubidium and 2 to 4 × 10-12 m2/s for iron, respectively. Diffusion experiments were also carried out for comparison. Potassium and rubidium might migrate slightly slower in the altered bentonite by iron corrosion than in ordinary compacted bentonite.

本文言語英語
ホスト出版物のタイトルScientific Basis for Nuclear Waste Management XXXIII
出版社Materials Research Society
ページ453-460
ページ数8
ISBN(印刷版)9781605111667
DOI
出版ステータス出版済み - 1 1 2009
イベント32nd Symposium on Scientific Basis for Nuclear Waste Management - St. Petersburg, ロシア連邦
継続期間: 5 24 20095 29 2009

出版物シリーズ

名前Materials Research Society Symposium Proceedings
1193
ISSN(印刷版)0272-9172

その他

その他32nd Symposium on Scientific Basis for Nuclear Waste Management
国/地域ロシア連邦
CitySt. Petersburg
Period5/24/095/29/09

All Science Journal Classification (ASJC) codes

  • 材料科学(全般)
  • 凝縮系物理学
  • 材料力学
  • 機械工学

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