Modeling of Radionuclide Migration Through Fractured Rock in a HLW Repository With Multiple Canisters

2008 ◽  
Vol 1107 ◽  
Author(s):  
Doo-Hyun Lim ◽  
Masahiro Uchida ◽  
Koichiro Hatanaka ◽  
Atsushi Sawada
Keyword(s):  
Numerical Model ◽  
Host Rock ◽  
Fractured Rock ◽  
Current Model ◽  
Design Parameters ◽  
Radionuclide Migration ◽  
Waste Package ◽  
Tunnel Diameter ◽  
Water Saturated ◽  
Hlw Repository

AbstractAn integrated numerical model for groundwater flow and radionuclide migration analyses in a water-saturated HLW repository with a multiple-canister configuration is developed by incorporating the heterogeneity of fractured host rock based on the previous multiple-canister model (MCFT2D [1, 2]). The current model incorporates i) heterogeneity of the fractured host rock represented stochastically by discrete fractures, ii) disposal-pit vertical emplacement concept, iii) representation of the waste package consisting of a waste canister and a bentonite-filled buffer, and iv) a user-determined repository configuration of multiple canisters using the repository parameters such as disposal tunnel spacing, waste package pitch, tunnel diameter, the number of tunnels in a repository, and the number of canisters in a tunnel. The current model can facilitate investigations into the effects of heterogeneous fractured host rock on water flow and nuclide migration for the different configurations of multiple canisters, as well as optimization of the repository design parameters in terms of release of nuclides from the repository.

Radionuclide Transport in a Water - Saturated Planar Fracture with Bentonite Extrusion

2007 ◽  
Vol 1006 ◽  
Author(s):  
R. A. Borrelli ◽  
J. Ahn
Keyword(s):  
Host Rock ◽  
Numerical Results ◽  
The Other ◽  
Radionuclide Transport ◽  
Radionuclide Migration ◽  
Migration Model ◽  
Advection Diffusion ◽  
Rock Interface ◽  
Water Saturated ◽  
Radionuclide Release

AbstractThis paper presents a radionuclide migration model that incorporates bentonite extrusion. The model consists of two parts: one for movement of water and bentonite in a planar fracture and the other for radionuclide transport by taking into account advection, diffusion, and sorption with moving bentonite particles. Numerical results indicate that strongly sorbing radionuclides are contained completely within the region of bentonite extrusion. This observation suggests importance of the region in the vicinity of buffer/rock interface in terms of impact on radionuclide release to surrounding host rock.

Modelling the Prototype Repository

2018 ◽  
Vol 482 (1) ◽  
pp. 241-260 ◽  
Author(s):  
V. Tsitsopoulos ◽  
S. Baxter ◽  
D. Holton ◽  
J. Dodd ◽  
S. Williams ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Host Rock ◽  
Hard Rock ◽  
Task Force ◽  
Fractured Rock ◽  
Fracture Network ◽  
Atmospheric Conditions ◽  
Predictive Capability ◽  
Rock Laboratory ◽  
Modelling Methodology

AbstractThe Prototype Repository (PR) tunnel is located at the Äspö Hard Rock Laboratory near Oskarshamn in the southeast of Sweden. In the PR tunnel, six full-sized deposition holes (8.37 m deep and 1.75 m in diameter) have been constructed. Each deposition hole is designed to mimic the Swedish reference system for the disposal of nuclear fuel, KBS-3V. The PR experiment is designed to provide a full-scale simulation of the emplacement of heat-generating waste. There are three phases to the experiment: (1) the open tunnel phase following construction, where both the tunnel and deposition holes are open to atmospheric conditions; (2) the emplacement of canisters (containing heaters), backfill and seal in the first section of the tunnel; and (3) the emplacement of canisters, backfill and seal in the second section of the tunnel. This work describes the numerical modelling, performed as part of the engineered barrier systems (EBS) Task Force, to understand the thermo-hydraulic (TH) evolution of the PR experiment and to provide a better understanding of the interaction between the fractured rock and bentonite surrounding the canister at the scale of a single deposition tunnel. A coupled integrated TH model for predicting the wetting and the temperature of bentonite emplaced in fractured rock was developed, accounting for the heterogeneity of the fractured rock. In this model, geometrical uncertainties of fracture locations are modelled by using several stochastic realizations of the fracture network. The modelling methodology utilized information available at early stages of site characterization and included site statistics for fracture occurrence and properties, as well as proposed installation properties of the bentonite. The adopted approach provides an evaluation of the predictive capability of models, it gives an insight of the uncertainties to data and demonstrates that a simplified equivalent homogeneous description of the fractured host rock is insufficient to represent the bentonite resaturation.

Numerical and Experimental Studies of Ballistic Compression Process in a Soft Recovery System

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Girijesh Mathur ◽  
Nachiketa Tiwari ◽  
Neha Chaturvedi
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Experimental Studies ◽  
Pressure Rise ◽  
Sensitivity Analyses ◽  
Design Parameters ◽  
Strong Positive Correlation ◽  
Compression Process ◽  
Recovery System ◽  
Two Parameters

Abstract A ballistic compression type soft recovery system can stop a free-flying supersonic projectile in a controlled manner. The moment such a projectile enters the System, a normal shock gets created and starts hurtling down, to kick off a train of events involving shock reflections, diaphragm rupture, shock merger, creation of new shocks and contact discontinuities, and expansion wave-shock interactions. A good understanding of these phenomena and sensitivity of the System's performance to changes in design parameters is needed to design an efficient soft recovery system. Unfortunately, not much information is available about this. The present work fills this gap. We have developed a numerical model for the system and conducted sensitivity analyses using four design parameters; pressure, molecular weight, the ratio of specific heats, and temperature of gas used in the system. We show that while there is a strong, positive correlation between the first two parameters and projectile deceleration, the other two parameters are less critical. We conducted experiments to corroborate our conclusions and improve our numerical model. Post such improvements, we found the difference between simulation and experimental data to be acceptable. Experiments also confirmed the findings of our sensitivity studies. Finally, we conducted a two-dimensional finite volume analysis to understand the reasons underlying the residual difference between our numerical and experimental data. We show that such differences are due to pressure-rise at a point once a shock passes by it, and such a rise in pressure is attributable to boundary layer effects.

Precisely Controlling Assembly Angle of Surface Tension Powered Self-Assembly for MEMS Microstructures

2007 ◽  
Author(s):  
Kai-Lin Pan ◽  
Yi-Lin Yan ◽  
Bin Zhou
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Self Assembly ◽  
Current Model ◽  
Three Dimensional ◽  
Design Parameters ◽  
Solder Paste ◽  
Surface Evolver ◽  
Final Assembly ◽  
The Relationship

How to integrate the microstructures which are made by various micro manufacturing methods into a functional system or device is the key to the application of MEMS technology. Solder self-assembly is based on surface tension with the properties of “self-organization”, low cost, batch processes and the compatibility with surface mount technology, which makes it be a challenging alternate technique. Solder self-assembly is based on the principle of surface energy minimization of molten solder material. During the process of minimizing the surface energy, surface tension can pull the horizontal hinged or hingeless plate up to a particular angle to achieve the minimal system energy. Finite element method is applied in this paper. MEMS self-assembly three-dimensional dynamic simulation model is developed by SURFACE EVOLVER. First, the model in this paper dynamically simulate the angle change of hinged plate during the process of evolvement of solder; second, the comparisons among the results from the current model and those from analytical two-dimensional model and three-dimensional static model are carried out; third, through Design of Experiments (DoE) with the application of the current model, the influences of design parameters such as pad size, pad geometry, and solder paste volume to the assembly angle are compared and discussed. Through changing the pad size, pad geometry and solder paste volume in SURFACE EVOLVER model, the corresponding final assembly angel from dynamic three-dimensional models are obtained. The relationship between design parameters to the assembly angle is concluded by the application of statistical analyses. The final angle can be controlled more effectively through synthetically optimize these parameters. It can provide effective guidance to the practical manufacturing of MEMS. Further research should focuses on the MEMS self-assembly experiment to intensively understand the relationship between the pad sizes, pad position, solder paste volume, hinge position, lock position and intermetallic compounds and the final assembly angle.

An Overview of the H12 Performance Assessment in Perspective

2002 ◽  
Vol 713 ◽  
Author(s):  
Kaname Miyahara ◽  
Hitoshi Makino ◽  
Tomoko Kato ◽  
Keiichiro Wakasugi ◽  
Atsushi Sawada ◽  
...  
Keyword(s):  
Performance Assessment ◽  
Host Rock ◽  
Comprehensive Evaluation ◽  
Near Field ◽  
Considerable Uncertainty ◽  
Wide Range ◽  
Safety Case ◽  
External Events ◽  
Hlw Repository ◽  
Current Stage

ABSTRACTThe H12 performance assessment (PA) provided a test for the robustness of a HLW repository system concept based on structured siting and design, taking account of a wide range of potentially suitable Japanese geological environments. The generic nature of the host rock in the H12 assessment means, however, that emphasis is placed verymuch on strong EBS performance. The assessment included a comprehensive evaluation of uncertainty and potentially detrimental factors, including perturbations due to external events and processes. Despite the considerable uncertainty at the current stage of the Japanese program, a safety case that is adequate for the aims of the assessment can be made by a strategy of employing conservatism where there is uncertainty and stressing the reliability and effectiveness of the performance of the near-field. The aim of this paper is to present the H12 PA in a way which makes the PA process clearer and the implications of the results more meaningful, both to workers within the PA field and to a wider technical audience.

scholarly journals Sorption-Capacity Limited Retardation of Radionuclides Transport in Water-Saturated Packing Materials

1984 ◽  
Vol 44 ◽  
Author(s):  
C. Pescatore ◽  
T. Sullivan
Keyword(s):  
Sorption Capacity ◽  
Retardation Factor ◽  
High Level Waste ◽  
Radionuclide Transport ◽  
Breakthrough Time ◽  
Packing Materials ◽  
Sorption Data ◽  
Waste Package ◽  
High Level ◽  
Water Saturated

AbstractRadionuclides breakthrough times as calculated through constant retardation factors obtained in dilute solutions are non-conservative. The constant retardation approach regards the solid as having infinite sorption capacity throughout the solid. However, as the solid becomes locally saturated, such as in the proximity of the waste form-packing materials interface, it will exhibit no retardation properties, and transport will take place as if the radionuclides were locally non-reactive. The magnitude of the effect of finite sorption capacity of the packing materials on radionuclide transport is discussed with reference to high-level waste package performance. An example based on literature sorption data indicates that the breakthrough time may be overpredicted by orders of magnitude using a constant retardation factor as compared to using the entire sorption isotherm to obtain a concentrationdependent retardation factor.

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