Migration behaviour of ferrous ion in compacted bentonite under reducing conditions controlled with potentiostat

Kazuya Idemitsu, Syeda Afsarun Nessa, Shigeru Yamazaki, Hirotomo Ikeuchi, Yaohiro Inagaki, Tatsumi Arima

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

7 Citations (Scopus)

Abstract

Carbon steel overpack is corroded by consuming oxygen introduced by repository construction after closure of the repository and then maintains the reducing environment in the vicinity of the repository. The migration of iron corrosion products through the buffer material will affect the migration of redox-sensitive radionuclides. Therefore, it is important to study the migration of iron corrosion products through the buffer material because it may affect the corrosion rate of overpack, and migration of redox-sensitive radionuclides. Electromigration experiments have been conducted with the source of iron ions supplied by anode corrosion of the iron coupon in compacted bentonite. The carbon steel coupon was connected as the working electrode to the potentiostat and was held at a constant supplied potential between - 650 to +300 mV vs. Ag/AgCl electrode for up to 168 hours. The amount of iron penetrated into a bentonite specimen was in good agreement with the calculated value from the corrosion current under the assumption that iron is dissolved as ferrous ions. A model using dispersion and electromigration could explain the measured iron profiles in the bentonite specimens. The fitted value of electromigration velocity depended on the potential supplied. On the other hand the fitted value of the dispersion coefficient did not depend on the potential supplied but a constant. This constant dispersion coefficient could be due to the much larger diffusion coefficient of ferrous ion in bentonite compared with the effect of mechanical dispersion. The experimental configurations used in this study are applicable to the examination of the migration behaviour of cations with the source of iron ions under a reducing condition controlled with a potentiostat.

Original languageEnglish
Title of host publicationMaterials Research Society Symposium Proceedings - Scientific Basis for Nuclear Waste Management XXXI
PublisherMaterials Research Society
Pages501-508
Number of pages8
ISBN (Print)9781605110790
DOIs
Publication statusPublished - 2008
Event31st International Symposium on the Scientific Basis for Nuclear Waste Management - Sheffield, United Kingdom
Duration: Sep 16 2007Sep 21 2007

Publication series

NameMaterials Research Society Symposium Proceedings
Volume1107
ISSN (Print)0272-9172

Other

Other31st International Symposium on the Scientific Basis for Nuclear Waste Management
CountryUnited Kingdom
CitySheffield
Period9/16/079/21/07

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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