Temperature dependence of long-term alteration rate for aqueous alteration of P0798 simulated waste glass under smectite forming conditions

Y. Inagaki, T. Saruwatari, K. Idemitsu, T. Arima, A. Shinkai, H. Yoshikawa, M. Yui

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

5 被引用数 (Scopus)

抄録

Several kinetic models have been proposed to evaluate the aqueous dissolution/ alteration rate of nuclear waste glass for long-term. However, reaction processes controlling the long-term rate are much more subjected to controversy. Temperature dependence of the long-term alteration rate is an essential issue to understand the rate controlling processes. In the present study, the static aqueous alteration tests were performed with a Japanese simulated waste glass P0798 as a function of temperature from 60°C to 120°C, and the temperature dependence of the long-term alteration rate was evaluated to understand the rate controlling processes. The tests were performed in 0.001M NaOH solution to maintain a constant solution pH of around 10 during the test period and to provide smectite forming conditions where smectite forms as the major secondary phase without zeolite formation. From the test results on dissolution of boron, the alteration rate at each temperature was analyzed by use of a water-diffusion model, The water-diffusion model used is based on a simple assumption; the glass alteration is controlled by water diffusion with ion-exchange between water (hydronium ion; H3O +) and soluble elements (B, Na, Li, etc) at the glass surface layer with the apparent diffusion coefficient Di. A good agreement was observed between the model analysis and the test results, and the value of Di was evaluated to be 1.2 × 10-22 m2/s at 60°C to 1.8 × 10-21 m2/s at 120°C. The Arrhenius plot of Di showed a good linearity to give the activation energy of 49 kJ/mol, which value is close to that for the residual dissolution rate of French waste glass (53 kJ/mol) by Gin [1], and is very close to that for ion-exchange in sodium aluminosilicate glass (49 kJ/mol) by McGrail [2]. These results suggest that water diffusion with ion-exchange can be the dominant process controlling the alteration rate under smectite forming conditions. At elevated temperatures (100°C and 120°C), however, the model-predicted boron releases deviated from the experimental data at the later stage beyond 50-80 days, which suggests that the alteration layer developing at the glass surface may evolve to be protective against the water diffusion to depress the alteration rate as the alteration proceeds.

本文言語英語
ホスト出版物のタイトル29th International Symposium on the Scientific Basis for Nuclear Waste Management XXIX
出版社Materials Research Society
ページ321-328
ページ数8
ISBN(印刷版)1558998896, 9781558998896
DOI
出版ステータス出版済み - 2006
イベント29th International Symposium on the Scientific Basis for Nuclear Waste Management XXIX - Ghent, ベルギー
継続期間: 9 12 20059 16 2005

出版物シリーズ

名前Materials Research Society Symposium Proceedings
932
ISSN(印刷版)0272-9172

その他

その他29th International Symposium on the Scientific Basis for Nuclear Waste Management XXIX
Countryベルギー
CityGhent
Period9/12/059/16/05

All Science Journal Classification (ASJC) codes

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

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