The Canadian program for sealing underground nuclear fuel waste vaults

1984 ◽  
Vol 21 (3) ◽  
pp. 593-596 ◽  
Author(s):  
R. S. Lopez ◽  
S. C. H. Cheung ◽  
D. A. Dixon
Keyword(s):  
Nuclear Fuel ◽  
Nuclear Reactor ◽  
Chemical Species ◽  
Management Program ◽  
Crushed Rock ◽  
Compacted Clay ◽  
Rock Formations ◽  
Engineered Barriers ◽  
Shaft Seals ◽  
Nuclear Fuel Waste

The general objective of the Canadian Nuclear Fuel Waste Management Program is the safety assessment of the disposal of nuclear reactor wastes in underground vaults mined in plutonic rock formations of the Canadian Shield. The isolation of waste forms from the surface environment is effected by a system of multiple additive barriers, each one engineered to a high degree of excellence. In successive order, these barriers are the container, the buffer, the backfill of vault openings, shaft and drift seals, and plugs in boreholes.The buffer is primarily a chemical barrier designed to retard the migration of chemical species that may corrode the containers, and also the outward migration of radionuclides in case of container failure. The buffer is an engineered mixture of high-purity expandable clays and sand or crushed rock. The backfill material in drifts and shafts is primarily a physical barrier, designed to stabilize the rock excavations and to retard the movement of radionuclides by advection.Specially designed drift and shaft seals are being considered, to enhance the function of the backfill. The seals are engineered barriers that may include reinforced concrete bulkheads, compacted clay and sand plugs, and grouting of the surrounding rock. Key words: nuclear fuel waste, underground disposal, engineered barriers, swelling clay, buffer, backfill, shaft seals.

Microbial Considerations and Studies in the Canadian Nuclear Fuel Waste Management Program

1994 ◽  
Vol 353 ◽  
Author(s):  
S. Stroes-Gascoyne ◽  
J.M. West
Keyword(s):  
Waste Management ◽  
Nuclear Fuel ◽  
Management Program ◽  
Gas Production ◽  
Compacted Clay ◽  
Radionuclide Migration ◽  
Survival And Growth ◽  
Nuclear Fuel Waste ◽  
Microbial Action ◽  
Microbial Effects

AbstractAECL Research is developing a concept for the permanent disposal of nuclear fuel waste. A program to address the potential effects of microbial action on the integrity of the multiple barrier system, on which the disposal concept is based has been initiated. This microbial program focusses on answering specific questions in areas such as the survival and growth of microbes in compacted clay buffer materials and the potential consequences for container corrosion and microbial gas production; microbial effects on transport of radionuclides through the buffer into the geosphere; the presence and activity of microbes in deep granitic groundwaters; and the effects of biofilms on radionuclide migration in the geosphere.

Thermal Behaviour of Backfill Material for a Nuclear Fuel Waste Disposal Vault

1989 ◽  
Vol 176 ◽  
Author(s):  
R.N. Yong ◽  
A.M.O. Mohamed ◽  
S.C.H. Cheung
Keyword(s):  
Mechanical Properties ◽  
Nuclear Fuel ◽  
Thermal Response ◽  
Management Program ◽  
Thermal And Mechanical Properties ◽  
Used Nuclear Fuel ◽  
Backfill Material ◽  
Rock Formations ◽  
Pressure Development ◽  
Nuclear Fuel Waste

ABSTRACTThe concept of disposing of used nuclear fuel in engineered rock formations is being studied in the Canadian Nuclear Fuel Waste Management Program. After the used fuel is emplaced in the vault, the vault would be backfilled. The backfill has to satisfy a number of engineering requirements. A reference backfill with satisfactory hydraulic, thermal and mechanical properties has already been selected.As the used fuel in the waste containers decays, heat will be generated and this heat will raise the temperature of the backfill material. The performance of the reference backfill material was evaluated over the temperature range 20–100°C. This paper addresses the results of experiments on thermal response and pressure development in the backfill for the period shortly after vault closure.

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.

scholarly journals Depleted Uranium Oxides and Silicates as Spent Nuclear Fuel Waste Package Fill Materials

1996 ◽  
Vol 465 ◽  
Author(s):  
C. W. Forsberg
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Chemical Species ◽  
Fission Products ◽  
Depleted Uranium ◽  
Improve Performance ◽  
Waste Package ◽  
Reducing Conditions ◽  
Nuclear Fuel Waste

ABSTRACTA new repository waste package (WP) concept for spent nuclear fuel (SNF) is being investigated. The WP uses depleted uranium (DU) to improve performance and reduce the uncertainties of geological disposal of SNF. The WP would be loaded with SNF. Void spaces would then be filled with DU (∼0.2 wt % 235U) dioxide (UO2) or DU silicate-glass beads.Fission products and actinides can not escape the SNF UO2 crystals until the UO2 dissolves or is transformed into other chemical species. After WP failure, the DU fill material slows dissolution by three mechanisms: (1) saturation of WP groundwater with DU and suppression of SNF dissolution, (2) maintenance of chemically reducing conditions in the WP that minimize SNF solubility by sacrificial oxidation of DU from the +4 valence state, and (3) evolution of DU to lower-density hydrated uranium silicates. The fill expansion minimizes water flow in the degraded WP. The DU also isotopically exchanges with SNF uranium as the SNF degrades to reduce long-term nuclear-criticality concerns.

Lifetimes of Titanium and Copper Containers for the Disposal of Used Nuclear Fuel

1991 ◽  
Vol 257 ◽  
Author(s):  
Lawrence H. Johnson ◽  
D.W. Shoesmith ◽  
B.M. Ikeda ◽  
F. King
Keyword(s):  
Nuclear Fuel ◽  
Bulk Solution ◽  
General Corrosion ◽  
Compacted Clay ◽  
Used Nuclear Fuel ◽  
Buffer Material ◽  
Using Data ◽  
Long Term Performance ◽  
Term Performance ◽  
Nuclear Fuel Waste

ABSTRACTTitanium and copper have been proposed as suitable container materials for disposal of nuclear fuel waste in plutonic rock of the Canadian Shield. Studies of the corrosion of these materials have led to the development of container failure models to predict long-term performance. Crevice corrosion and hydrogen-induced cracking of titanium have been identified as potential failure mechanisms, and these two processes have been studied in detail. Using data from these studies as well as a number of conservative assumptions, titanium container lifetimes of 1200 to 7000 a have been estimated. For copper, general corrosion has been studied in detail in bulk solution and in compacted clay-based buffer material. Results indicate that the copper corrosion rate is likely to be controlled by the rate of transport of copper species away from the container surface. An assessment of copper pitting data suggests that pitting is an extremely improbable failure mechanism. The copper container failure model predicts minimum container lifetimes of 30 000 a. The results demonstrate that long lifetime containment can be provided, should performance assessment studies indicate the need for such an option.

A Review of Progress in the Canadian Nuclear Fuel Waste Management Program

1985 ◽  
Vol 50 ◽  
Author(s):  
R. B. Lyon ◽  
L. H. Johnson
Keyword(s):  
Waste Management ◽  
Nuclear Fuel ◽  
Management Program ◽  
Selection Methods ◽  
Transportation Fuel ◽  
Waste Immobilization ◽  
Fuel Storage ◽  
And Performance ◽  
Nuclear Fuel Waste ◽  
Made In

AbstractThe Canadian Nuclear Fuel Waste Management Program is reviewed, illustrating the progress that has been made in assessing the concept of disposal of nuclear fuel waste in plutonic rock of the Canadian Shield. Research is being conducted into used fuel storage and transportation, fuel waste immobilization, site characterization and selection methods, and performance assessment modelling. Details of achievements in these areas are outlined, and results of the most recent interim assessment are discussed.

Predicted Behavior of Technetium in a Geological Disposal Vault For Used Nuclear Fuel - Ramifications of a Recent Determination of the Enthalpy of Formation of TcO2(cr)

1995 ◽  
Vol 412 ◽  
Author(s):  
R. J. Lemire ◽  
D. J. Jobe
Keyword(s):  
Nuclear Fuel ◽  
Management Program ◽  
Heat Of Solution ◽  
Used Nuclear Fuel ◽  
A Value ◽  
Reducing Conditions ◽  
Congruent Dissolution ◽  
Nuclear Fuel Waste ◽  
The Enthalpy Of Formation

AbstractRecently, we reported a value of ΔH°(TcO2(cr)) = -(458 ± 6) kJ·mol-1based on heat of solution measurements. The implications of this value on the database used in the Canadian Nuclear Fuel Waste Management Program for the evaluation of the technetium released by congruent dissolution of used UO2 fuel have now been assessed.It is probable that the Tc(IV) oxides are more stable than previously predicted and, hence, they are less likely to be oxidized to TcO4(aq) under moderately reducing conditions. We have revised earlier calculations done to predict the solution concentrations of technetium species in a vault as a function of the oxidation conditions in model groundwaters.

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