Plutonium diffusivity in compacted bentonite

Kazuya Idemitsu, Katsuhiko Ishiguro, Yasuhisa Yusa, Noriaki Sasaki, Naomi Tsunoda

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Abstract

Measurements on plutonium diffusivity in water-saturated compacted bentonite were carried out. Representative specimens of sodium bentonite were taken from the Tsukinuno and Kuroishi mines situated in northeast Japan. Tsukinuno bentonite was divided into three types: raw type, purified Na-type, and H-type which was prepared by treating Na-type bentonite with hydrochloric acid. Kuroishi bentonite contained chlorite as impurity. H-type bentonite was used as reference for the convenience of profile measurement in bentonite, since plutonium diffusivity in H-type bentonite was considered to be larger than that in Na-type bentonite because of low pH and low swelling pressure of H-type bentonite. Sampled bentonite was compacted into pellets of 20 mm in diameter and 20 mm in height. Bulk densities of these specimens were 1200-1800 kg/m3 for purified Na-type and H-type bentonite and 1600 kg/m3 for raw type bentonite. Plutonium profiles obtained in H-type bentonite can be explained by diffusion equation with constant concentration source. Diffusivity ranges from 10-13 to 10 12 m2/s for H-type and Kuroishi impure sodium bentonite. Diffusivity in both raw type and purified Tsukinuno bentonite was was estimated to less than 10-14 M2/s. Diffusivity in H-type bentonite showed a tendency to decrease with increasing density. Influence of in bentonite was also studied. Quartz content up to 50% or hematite content up to 1% did not influence diffusivity significantly in H-type bentonite. The chemical species of plutonium in pore water of Na-type and H-type were estimated Pu(OH)3-; and PuO2-, respectively.

Original languageEnglish
Pages (from-to)455-462
Number of pages8
JournalEngineering Geology
Volume28
Issue number3-4
DOIs
Publication statusPublished - Jan 1 1990
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology
  • Geology

Cite this

Idemitsu, K., Ishiguro, K., Yusa, Y., Sasaki, N., & Tsunoda, N. (1990). Plutonium diffusivity in compacted bentonite. Engineering Geology, 28(3-4), 455-462. https://doi.org/10.1016/0013-7952(90)90028-Y