Use of the QUasI-Stationary State Approximation to Determine the Migration of Mineral Alteration Zones at a Natural Analogue for the Disturbed Zone of a Cementitious Radioactive Waste Repository

MRS Proceedings ◽

10.1557/proc-333-639 ◽

1993 ◽

Vol 333 ◽

Author(s):

A.V. Chambers

Keyword(s):

Radioactive Waste ◽

Stationary State ◽

Radioactive Waste Disposal ◽

Natural Analogue ◽

Radioactive Waste Repository ◽

Alteration Zones ◽

State Approximation ◽

Quasi Stationary State ◽

Waste Repository ◽

Mineral Alteration

ABSTRACTCalculation of the movement of chemical fronts over long timescales could be important in underpinning performance assessments for radioactive waste disposal. A quasi-stationary state model, MARQUISS (Mineral Alteration Reactions using the QUasI-Statίonary State approximation), has been developed to achieve this objective by avoiding many of the problems encountered using more conventional approaches to coupled chemistry and transport calculations. MARQUISS simulates advective, dispersive and diffusive transport through a one-dimensional porous medium coupled with the chemical kinetics of mineral precipitation and dissolution. A description of its development and verification for simple systems is provided, together with its application in a study of the migration of mineral alteration zones at a natural analogue for a cementitious radioactive waste repository located at Maqarin in northern Jordan.

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Planning of Large-Scale In-Situ Gas Generation Experiment in Korean Radioactive Waste Repository

ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management, Volume 1 ◽

10.1115/icem2010-40020 ◽

2010 ◽

Cited By ~ 2

Author(s):

Juyoul Kim ◽

Sukhoon Kim ◽

Jin Beak Park ◽

Sunjoung Lee

Keyword(s):

Radioactive Waste ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Large Scale ◽

Radioactive Waste Disposal ◽

Gas Generation ◽

Radioactive Waste Repository ◽

Waste Repository

In the Korean LILW (Low- and Intermediate-Level radioactive Waste) repository at Gyeongju city, the degradation of organic wastes and the corrosion of metallic wastes and steel containers would be important processes that affect repository geochemistry, speciation and transport of radionuclides during the lifetime of a radioactive waste disposal facility. Gas is generated in association with these processes and has the potential threat to pressurize the repository, which can promote the transport of groundwater and gas, and consequently radionuclide transport. Microbial activity plays an important role in organic degradation, corrosion and gas generation through the mediation of reduction-oxidation reactions. The Korean research project on gas generation is being performed by Korea Radioactive Waste Management Corporation (hereafter referred to as “KRMC”). A full-scale in-situ experiment will form a central part of the project, where gas generation in real radioactive low-level maintenance waste from nuclear power plants will be done as an in-depth study during ten years at least. In order to examine gas generation issues from an LILW repository which is being constructed and will be completed by the end of December, 2012, two large-scale facilities for the gas generation experiment will be established, each equipped with a concrete container carrying on 16 drums of 200 L and 9 drums of 320 L of LILW from Korean nuclear power plants. Each container will be enclosed within a gas-tight and acid-proof steel tank. The experiment facility will be fully filled with ground water that provides representative geochemical conditions and microbial inoculation in the near field of repository. In the experiment, the design includes long-term monitoring and analyses for the rate and composition of gas generated, and aqueous geochemistry and microbe populations present at various locations through on-line analyzers and manual periodical sampling. A main schedule for establishing the experiment facility is as follows: Completion of the detailed design until the second quarter of the year 2010; Completion of the manufacture and on-site installation until the second quarter of the year 2011; Start of the operation and monitoring from the third quarter of the year 2011.

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A New Natural Analogue Study of the Interaction of Low-Alkali Cement Leachates and the Bentonite Buffer of a Radioactive Waste Repository

MRS Proceedings ◽

10.1557/proc-1107-493 ◽

2008 ◽

Vol 1107 ◽

Author(s):

W. Russell Alexander ◽

Carlo A. Arcilla ◽

Ian G. McKinley ◽

Hideki Kawamura ◽

Yoshiaki Takahashi ◽

...

Keyword(s):

Radioactive Waste ◽

Laboratory Data ◽

Construction Materials ◽

The Philippines ◽

Current Status ◽

Natural Analogue ◽

Radioactive Waste Repository ◽

Early Results ◽

Slow Kinetics ◽

Waste Repository

AbstractBentonite plays a significant barrier role in many radioactive waste repository designs, where it has been chosen due to its favourable properties such as plasticity, swelling capacity, colloid filtration, low hydraulic conductivity and its stability in relevant geological environments. However, bentonite is unstable at high pH meaning that it could lose its favourable properties if interacted with hyperalkaline leachates from concrete construction materials (e.g. tunnel liners, grouts, etc.), seals and plugs and/or cementitious wastes in a repository. This fact has forced several national programmes to assess alternative construction and sealing materials such as low alkali cements. Recently, it has been assumed that the lower pH (typically pH 10-11) leachates of such cements will degrade bentonite to a much lesser degree than ‘standard’ OPC-based cement leachates (generally with an initial pH>13).To date, few laboratory or in situ URL (underground rock laboratory) data are available to support the use of low alkali cements in conjunction with bentonites, partly because of the very slow kinetics involved. Consequently, a new project has focussed on finding an appropriate natural analogue site to provide long-term supporting data which will avoid the kinetic constraints of laboratory and URL experiments. Early results have identified an initial, very promising site at Mangatarem in the Philippines, where a quarry excavating bentonite and zeolites is found in the sedimentary carapace of the Zambales ophiolite. In the immediate vicinity of the quarry, ophiolite-derived hyperalkaline groundwaters are present and further field work (including geophysics surveys and borehole drilling) are now being planned to assess regional bentonite/hyperalkaline groundwater interaction. This paper presents an overview of the current status of the project and assesses the relevance of the study to improving understanding of low-alkali cement leachate/bentonite interaction.

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