The State of the Science and Technology in Deep Borehole Disposal of Nuclear Waste

Mallants, Dirk; Travis, Karl P.; Chapman, Neil; Brady, Patrick V.; Griffiths, Hefin

doi:10.3390/en13040833

Cited by 17 publications

(15 citation statements)

References 11 publications

(29 reference statements)

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“…(3) Update pressure with the updated density (4) Step 2 is repeated until the results converge Allowing the viscosity (and density) to depend on temperature across the 3000 m deep depth profile resulted in a curvi-linear decrease from 12 × 10 −4 Pa:S at the top of the model to 4 × 10 −4 Pa:S at 3000 m depth. The temperature increase over this distance is 60 °C.…”

Section: Conceptual Model Setup and Scenariosmentioning

confidence: 99%

“…Underground nuclear waste disposal may occur in mined tunnels and caverns at a depth of a few hundred meters [1,2] or in vertical boreholes at depths up to several kilometres [3,4]. The host rock in which these geologic disposal facilities (GDF) are being developed may be either a lower strength sedimentary rock such as clay [5] or a higher strength rock such as granite [6].…”

Section: Introductionmentioning

confidence: 99%

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Coupled Heat-Mass Transport Modelling of Radionuclide Migration from a Nuclear Waste Disposal Borehole

Lari

Mallants

2022

Geofluids

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Disposal of radioactive waste originating from reprocessing of spent research reactor fuel typically includes stainless steel canisters with waste immobilised in a glass matrix. In a deep borehole disposal concept, waste packages could be stacked in a disposal zone at a depth of one to potentially several kilometres. This waste will generate heat for several hundreds of years. The influence of combining a natural geothermal gradient with heat from decaying nuclear waste on radionuclide transport from deep disposal boreholes is studied by implementing a coupled heat-solute mass transport modelling framework, subjected to depth-dependent temperature, pressure, and viscosity profiles. Several scenarios of waste-driven heat loads were investigated to test to what degree, if any, the additional heat affects radionuclide migration by generating convection-driven transport. Results show that the heat output and the calculated radioactivity at a hypothetical near-surface observation point are directly correlated; however, the overall impact of convection-driven transport is small due to the short duration (a few hundred years) of the heat load. Results further showed that the calculated radiation dose at the observation point was very sensitive to the magnitude of the effective diffusion parameter of the host rock. Coupled heat-solute mass transport models are necessary tools to identify influential processes regarding deep borehole disposal of heat-generating long-lived radioactive waste.

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Section: Conceptual Model Setup and Scenariosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Coupled Heat-Mass Transport Modelling of Radionuclide Migration from a Nuclear Waste Disposal Borehole

Lari

Mallants

2022

Geofluids

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“…Nuclear power plays a great role in promoting energy transition, and the safety, maintenance, and overhaul of nuclear power facilities are crucial links in the nuclear power industry (Larsen and Babineau, 2020 ; Liu et al, 2020 ; Mallants et al, 2020 ; Park and Lee, 2020 ; Zhao et al, 2020 ). In recent years, more and more robots have been developed to serve nuclear power plants (Kim et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Neural network aided flexible joint optimization with design of experiment method for nuclear power plant inspection robot

Wang

Li²,

Ma³

et al. 2023

Front. Neurorobot.

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IntroductionThe flexible joint is a crucial component for the inspection robot to flexible interaction with nuclear power facilities. This paper proposed a neural network aided flexible joint structure optimization method with the Design of Experiment (DOE) method for the nuclear power plant inspection robot.MethodsWith this method, the joint's dual-spiral flexible coupler was optimized regarding the minimum mean square error of the stiffness. The optimal flexible coupler was demonstrated and tested. The neural network method can be used for the modeling of the parameterized flexible coupler with regard to the geometrical parameters as well as the load on the base of the DOE result.ResultsWith the aid of the neural network model of the stiffness, the dual-spiral flexible coupler structure can be fully optimized to a target stiffness, 450 Nm/rad in this case, and a given error level, 0.3% in the current case, with regard to the different loads. The optimal coupler is fabricated with wire electrical discharge machining (EDM) and tested.DiscussionThe experimental results demonstrate that the load and angular displacement keep a good linear relationship in the given load range and this optimization method can be used as an effective method and tool in the joint design process.

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“…Briefly, in such facilities, the waste is placed in conditioned galleries buried in deep geological repositories in specific host-rock environments. For instance, depending on the country and available options in saline, clay, or granitic formations, different options are considered concerning the host-rock [2][3][4][5]. This disposal strategy involves an Engineered Barrier System (EBS) designed to mitigate the potential release of radionuclides from the repository to the nearand far-field.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

Garcia

Lützenkirchen

Huguenel³

et al. 2021

Minerals

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In this work, the adsorption behavior of Sr onto a synthetic iron(III) oxide (hematite with traces of goethite) has been studied. This solid, which might be considered a representative of Fe3+ solid phases (iron corrosion products), was characterized by X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS), and its specific surface area was determined. Both XRD and XPS data are consistent with a mixed solid containing more than 90% hematite and 10% goethite. The solid was further characterized by fast acid-base titrations at different NaCl concentrations (from 0.1 to 5 M). Subsequently, for each background NaCl concentration used for the acid-base titrations, Sr-uptake experiments were carried out involving two different levels of Sr concentration (1·10−5 and 5·10−5 M, respectively) at constant solid concentration (7.3 g/L) as a function of −log([H+]/M). A Surface Complexation Model (SCM) was fitted to the experimental data, following a coupled Pitzer/surface complexation approach. The Pitzer model was applied to aqueous species. A Basic Stern Model was used for interfacial electrostatics of the system, which includes ion-specific effects via ion-specific pair-formation constants, whereas the Pitzer-approach involves ion-interaction parameters that enter the model through activity coefficients for aqueous species. A simple 1-pK model was applied (generic surface species, denoted as >XOH−1/2). Parameter fitting was carried out using the general parameter estimation software UCODE, coupled to a modified version of FITEQL2. The combined approach describes the full set of data reasonably well and involves two Sr-surface complexes, one of them including chloride. Monodentate and bidentate models were tested and were found to perform equally well. The SCM is particularly able to account for the incomplete uptake of Sr at higher salt levels, supporting the idea that adsorption models conventionally used in salt concentrations below 1 M are applicable to high salt concentrations if the correct activity corrections for the aqueous species are applied. This generates a self-consistent model framework involving a practical approach for semi-mechanistic SCMs. The model framework of coupling conventional electrostatic double layer models for the surface with a Pitzer approach for the bulk solution earlier tested with strongly adsorbing solutes is here shown to be successful for more weakly adsorbing solutes.

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The State of the Science and Technology in Deep Borehole Disposal of Nuclear Waste

Cited by 17 publications

References 11 publications

Coupled Heat-Mass Transport Modelling of Radionuclide Migration from a Nuclear Waste Disposal Borehole

Coupled Heat-Mass Transport Modelling of Radionuclide Migration from a Nuclear Waste Disposal Borehole

Neural network aided flexible joint optimization with design of experiment method for nuclear power plant inspection robot

Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

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