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Journal Articles

Using natural systems evidence to test models of transformation of montmorillonite

Savage, D.*; Wilson, J.*; Benbow, S.*; Sasamoto, Hiroshi; Oda, Chie; Walker, C.*; Kawama, Daisuke*; Tachi, Yukio

Applied Clay Science, 195, p.105741_1 - 105741_11, 2020/09

 Times Cited Count:1 Percentile:0.02(Chemistry, Physical)

Safety functions for the clay buffer in a repository for high-level radioactive waste (HLW) are fulfilled if the presence of montmorillonite with high swelling capacity and low permeability is maintained in the long-term. The transformation of montmorillonite to the non-swelling mineral likely illite is addressed in most safety assessments by using simple semi-empirical kinetic models, but this approach contrasts with more complex reactive-transport simulations. In the present study, reactive-transport simulations are compared with simple semi-empirical kinetic models. Results suggest that reactive-transport simulations err on the side of conservatism, but may produce unrealistic estimates of illitization. This comparison demonstrates that reactive-transport models may be carefully applied to simulate the long-term evolution of near field environment for HLW disposal.

Journal Articles

Natural systems evidence for the effects of temperature and the activity of aqueous silica upon montmorillonite stability in clay barriers for the disposal of radioactive wastes

Savage, D.*; Wilson, J.*; Benbow, S.*; Sasamoto, Hiroshi; Oda, Chie; Walker, C.*; Kawama, Daisuke*; Tachi, Yukio

Applied Clay Science, 179, p.105146_1 - 105146_10, 2019/10

 Times Cited Count:5 Percentile:57.36(Chemistry, Physical)

Natural systems evidence for the effects of temperature and the activity of aqueous silica upon montmorillonite stability was evaluated. Thermodynamic modeling using three different TDBs shows that stability fields for montmorillonite exist from 0 to 140$$^{circ}$$C, but at low values of silica activity, a stability field for illite replaces that for montmorillonite. Pore fluid chemical and mineralogical data for sediments from ODP sites from offshore Japan show a trend from montmorillonite + amorphous silica stability at temperatures up to 60$$^{circ}$$C to that for illite + quartz at higher temperatures. However, even over very long timescales ($$gg$$ 1 Ma), smectite does not transform to illite under thermodynamically-favourable conditions at temperatures less than 80$$^{circ}$$C.

Journal Articles

Implication for long-term behavior of radionuclides in deep underground on the basis of natural analogue phenomena

Nagano, Tetsushi; Nakayama, Shinichi

Genshiryoku Bakkuendo Kenkyu, 8(1), p.81 - 88, 2001/09

Japan Atomic Energy Research Institute has studied to predict the long-term migration of radionuclides in geosphere in terms of radioactive waste disposal. The research activity was introduced to junior high and high school students at a seminar of the Mineralogical Society of Japan. The content of the lecture was summarized.

Journal Articles

SHRIMP measurements of U and Pb isotopes in the Koongarra secondary ore deposit, northern Australia

Nagano, Tetsushi; Sato, Tsutomu*; Williams, I. S.*; Zaw, M.*; Payne, T. E.*; Airey, P. L.*; Yanase, Nobuyuki; Isobe, Hiroshi*; Onuki, Toshihiko

Geochemical Journal, 34(5), p.349 - 358, 2000/10

 Times Cited Count:4 Percentile:14.24(Geochemistry & Geophysics)

no abstracts in English

JAEA Reports

Analogue studies in the alligator rivers region; In-situ measurement of uranium series nuclides with SHRIMP

Nagano, Tetsushi; Sato, Tsutomu*; Yanase, Nobuyuki; Isobe, Hiroshi*; Onuki, Toshihiko; I.S.Williams*; M.Zaw*; T.E.Payne*; P.L.Airey*

JAERI-Research 99-024, 52 Pages, 1999/03

JAERI-Research-99-024.pdf:3.3MB

no abstracts in English

JAEA Reports

Progress report on safety research on radioactive waste management for the period April 1995 to March 1996

Sekine, Keiichi; Muraoka, Susumu; Bamba, Tsunetaka

JAERI-Review 97-007, 61 Pages, 1997/03

JAERI-Review-97-007.pdf:2.18MB

no abstracts in English

JAEA Reports

Progress report on safety research on radioactive waste management for the period April 1993 to March 1995

Sekine, Keiichi; Muraoka, Susumu; Bamba, Tsunetaka

JAERI-Review 96-005, 97 Pages, 1996/03

JAERI-Review-96-005.pdf:2.88MB

no abstracts in English

Oral presentation

Use of natural analogues to develop and test models of radionuclide release and transport in uplift / erosion scenarios

Klein, L.*; Hardie, S.*; McKinley, I.*; Tachi, Yukio; Shibata, Masahiro; Amano, Yuki; Takase, Hiroyasu*

no journal, , 

The uplift / erosion is treated as a special perturbation scenario for the safety assessment of the geological disposal, due to the Japanese tectonic setting, the impact of uplift must be considered as part of "likely" repository evolution. In an initial study, a simple uplift and erosion scenario was assessed with resultant changes in solubility and sorption of key radionuclides. A special challenge here is development of models and associated databases to quantify the impact of rock mechanical, hydrogeological and bio-geochemical changes on radionuclide migration both in the EBS and in the geosphere. There are great uncertainties with any laboratory studies to investigate the processes involved and therefore natural analogues have great potential here. The paper will list and discuss the key safety-relevant processes and potential analogue studies by considering both data mining of existing knowledge bases and also new projects that are specifically focused on this application.

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