The geochemical environment of nuclear fuel waste disposal

1996 ◽  
Vol 42 (4) ◽  
pp. 401-409 ◽  
Author(s):  
M. Gascoyne
Keyword(s):  
Nuclear Fuel ◽  
Waste Disposal ◽  
Canadian Shield ◽  
Geochemical Environment ◽  
Research Areas ◽  
Reducing Conditions ◽  
Backfill Materials ◽  
The Stability ◽  
Underground Research Laboratory ◽  
Nuclear Fuel Waste

The concept for disposal of Canada's nuclear fuel waste in a geologic environment on the Canadian Shield has recently been presented by Atomic Energy of Canada Limited (AECL) to governments, scientists, and the public, for review. An important part of this concept concerns the geochemical environment of a disposal vault and includes consideration of rock and groundwater compositions, geochemical interactions between rocks, groundwaters, and emplaced vault materials, and the influences and significance of anthropogenic and microbiological effects following closure of the vault. This paper summarizes the disposal concept and examines aspects of the geochemical environment. The presence of saline groundwaters and reducing conditions at proposed vault depths (500–1000 m) in the Canadian Shield has an important bearing on the stability of the used nuclear fuel, its container, and buffer and backfill materials. The potential for introduction of anthropogenic contaminants and microbes during site investigations and vault excavation, operation, and sealing is described with examples from AECL's research areas on the Shield and in their underground research laboratory in southeastern Manitoba. Keywords: nuclear waste disposal, geochemistry, Canadian Shield, groundwater chemistry.

Materials Research for the Canadian Nuclear Fuel Waste Management Program

1981 ◽  
Vol 6 ◽  
Author(s):  
Donald J. Cameron
Keyword(s):  
Nuclear Fuel ◽  
Waste Disposal ◽  
Hard Rock ◽  
Technology Development ◽  
Management Program ◽  
Materials Research ◽  
Backfill Materials ◽  
Nuclear Fuel Waste ◽  
Irradiated Fuel ◽  
Selection Of

ABSTRACTNuclear fuel waste disposal research in Canada is concentrating on hard-rock disposal. The research programs concerned with the man-made components of the disposal system are reviewed. Irradiated fuel and solidified reprocessing wastes are both being researched, as are durable containers, and buffer and backfill materials. This review concentrates mainly on the more scientific aspects of the research, which contribute to the selection of preferred options for the various components of the system, and which support directly or indirectly the safety analysis of the disposal concept. Some technology development is included in the program now, and this is expected to expand as confidence in the acceptability of the disposal concept grows.

Modelling the Consumption of Oxygen by Container Corrosion and Reaction with Fe(II)

1995 ◽  
Vol 412 ◽  
Author(s):  
M. Kolář ◽  
F. King
Keyword(s):  
Nuclear Fuel ◽  
Waste Disposal ◽  
Corrosion Reaction ◽  
Crushed Granite ◽  
Backfill Materials ◽  
Nuclear Fuel Waste ◽  
Oxidation Of Organics

AbstractA model is described that predicts the rate of O2 consumption in a sealed nuclear fuel waste disposal vault as a result of container corrosion, reaction with biotite and the oxidation of organics and other oxidizable impurities in the clay. The most important reactions leading to the consumption of O2 for Cu containers in a conceptual Canadian disposal vault are container corrosion, the oxidation of dissolved Cu(I) and the oxidation of organics and other impurities in the clay. Consumption of O2 by the oxidation of dissolved Fe(II) from biotite is significant in backfill materials containing crushed granite and in the rock itself. The O2 initially trapped in the disposal vault is predicted to be consumed in between 50 and 670 a.

Calculated uranium solubility in groundwater: implications for nuclear fuel waste disposal

1982 ◽  
Vol 60 (13) ◽  
pp. 1759-1766 ◽  
Author(s):  
Bruce Goodwin
Keyword(s):  
Nuclear Fuel ◽  
Waste Disposal ◽  
Chemical Equilibrium ◽  
Temperature Range ◽  
Factors Influencing ◽  
The Stability ◽  
Nuclear Fuel Waste ◽  
Equilibrium Calculations ◽  
Effect Of The Composition

Uranium solubilities of the order of 10−10 M have been calculated for a range of conditions which are considered to be representative of those expected in a Canadian nuclear fuel waste disposal vault. Factors taken into consideration include the pH and Eh range expected for deep groundwaters, the projected temperature range near a nuclear fuel waste disposal vault, the effect of the composition of two representative groundwaters, the effect of non-ideality, and the effect of the stability of several uranium solids.The model used in these calculations is based on the assumption of chemical equilibrium. Calculations show that the most important factors influencing uranium solubility under the postulated conditions are pH and Eh.These results applied to an assessment of the nuclear fuel waste disposal program suggest that uranium concentrations will be very low in the disposal vault, and that the irradiated UO2 fuel matrix will remain relatively intact for long periods of time.

Studies Of Cement Grouts And Grouting Techniques For Sealing A Nuclear Fuel Waste Disposal Vault

1988 ◽  
Vol 137 ◽  
Author(s):  
Maria Onofreic ◽  
Malcolm N. Gray ◽  
L. Douglas Keil ◽  
Roland Pusch
Keyword(s):  
Nuclear Fuel ◽  
Waste Disposal ◽  
Ionic Composition ◽  
Field Tests ◽  
Volume Ratio ◽  
Field Trials ◽  
Fracture Aperture ◽  
Underground Research Laboratory ◽  
Increasing Temperature ◽  
Nuclear Fuel Waste

AbstractA cement-based grout (90% Type 50, 10% silica fume, 0.4 < water-to-cement ratio, w/c < 0.6) has been used in field trials at AECL's Underground Research Laboratory in Canada and at the OECD/NEA Stripa Mine in Sweden, to evaluate suitable grouts and grouting techniques that could be used for sealing a nuclear fuel waste disposal vault mined deep in granite. Laboratory studies have been carried out to determine the following grout properties: hydraulic conductivity (k); resistance to piping and erosion during setting; influence of grout on the pH and chemical composition of water permeating grouted rock; and the ability of the grout to self-seal after fracturing.Laboratory tests have confirmed the low intrinsic k of these cement mixtures (10−14 m/s). Using a specially developed cone-in-cone apparatus, we have studied the effect of fracture dilation and temperature changes on the k of thin films of cement. If fractured, the grout has an ability to self-seal and the rate of self-sealing increases with increasing temperature.The pH and ionic composition of the water permeating grouted fractured granite rock were found to vary with grouted fracture aperture and grout/rock volume ratio. The field tests demonstrated that grout can penetrate and seal very fine fissures (apertures less than 50 μm).

Thermal and physical properties of candidate buffer–backfill materials for a nuclear fuel waste disposal vault

1989 ◽  
Vol 26 (4) ◽  
pp. 629-639 ◽  
Author(s):  
H. S. Radhakrishna ◽  
H. T. Chan ◽  
A. M. Crawford ◽  
K. C. Lau
Keyword(s):  
Hydraulic Conductivity ◽  
Nuclear Fuel ◽  
Waste Disposal ◽  
Management Program ◽  
Buffer Material ◽  
Backfill Materials ◽  
And Performance ◽  
Nuclear Fuel Waste ◽  
Clay Barriers ◽  
Ontario Hydro

As part of the Canadian Nuclear Fuel Waste Management Program, Ontario Hydro has, over several years, conducted research into the behaviour and performance of buffer–backfill for the proposed nuclear fuel waste disposal vault. In this paper, a review has been made of laboratory studies made at Ontario Hydro on the thermal properties, strength, hydraulic conductivity, and compactability of clay-based buffer materials. The results of this work have enabled the formulation of selection criteria for the buffer material mix for the prototype Canadian nuclear fuel waste disposal scheme. Key words: bentonites, buffer, backfill, nuclear waste disposal, thermal conductivity, clays, hydraulic conductivity, compaction, clay barriers, clay seals, shrinkage.

The surface water model for assessing Canada's nuclear fuel waste disposal concept

1993 ◽  
Vol 13 (2) ◽  
pp. 153-170 ◽  
Author(s):  
G.A. Bird ◽  
M. Stephenson ◽  
R.J. Cornett
Keyword(s):  
Surface Water ◽  
Nuclear Fuel ◽  
Waste Disposal ◽  
Water Model ◽  
Nuclear Fuel Waste
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