Modelling Multi-Phase Flow Phenomena in Concrete Barriers Used for Geological Disposal of Radioactive Waste

2007 ◽  
Author(s):  
Dirk Mallants ◽  
Diederik Jacques ◽  
Janez Perko
Keyword(s):  
Radioactive Waste ◽  
Hydrogen Gas ◽  
Phase Flow ◽  
Gas Generation ◽  
Boom Clay ◽  
In Situ Experiments ◽  
Production Of Hydrogen ◽  
Multi Phase Flow ◽  
Engineered Barriers ◽  
Multi Phase

Gas generation and gas transport phenomena occur in geological repositories of radioactive waste. This has been extensively studied over the past ten years, usually within the framework of international projects (MEGAS, PROGRESS, etc.). These studies indicate that the production of hydrogen by anaerobic corrosion of metals is the most important source for gas generation. Laboratory and in situ experiments carried out at SCK•CEN indicate that, in the presence of Boom Clay (the reference geologic formation for deep disposal studies in Belgium), carbon steel suffers generalised corrosion estimated conservatively at 1 μm y−1. Simulations with the finite difference multi-phase flow code TOUGH2 were carried out in an attempt to quantify the effects of hydrogen gas generation on desaturation of initially saturated concrete components of the disposal gallery and the concomitant expulsion of cementitious pore-water into the surrounding host formation. Several simulation cases were considered and addressed differences in initial water saturation degree of concrete, hydrogen gas generation rate, and material porosity. Several conceptual models have been developed to better understand the phenomena at work in the transport of gas in the cementitious engineered barriers and Boom Clay. Multi-phase flow modelling was found to be helpful to get insight into the phenomenology of coupled water-gas flow in the cementitious engineered barriers. However, modeling the discontinuous variation in the conductivity of the clay relative to the gas (creation of preferential pathways) requires incorporation of geomechanical processes in conventional models based on the laws of two-phase flow.

Implementation of a Geological Disposal Facility (GDF) in the UK by the NDA Radioactive Waste Management Directorate (RWMD): Coupled Modelling of Gas Generation and Multiphase Flow Between the Co-Located ILW/LLW and HLW/SF Components of a GDF

2009 ◽  
Author(s):  
Alex Bond ◽  
George Towler ◽  
Alan Paulley ◽  
Simon Norris
Keyword(s):  
Radioactive Waste ◽  
Multiphase Flow ◽  
White Paper ◽  
Phase Flow ◽  
Gas Generation ◽  
Geological Disposal ◽  
Disposal Facility ◽  
Multi Phase Flow ◽  
The Uk ◽  
Multi Phase

In June 2008 the UK government published a ‘White Paper’ as part of the “Managing Radioactive Waste Safety” (MRWS) programme to provide a framework for managing higher activity radioactive wastes in the long-term through geological disposal. The White Paper identifies that there are benefits to disposing all of the UK’s higher activity wastes (Low and Intermediate Level Waste (LLW and ILW), High Level Waste (HLW), Spent Fuel (SF), Uranium (U) and Plutonium (Pu)) at the same site, and this is currently the preferred option. It also notes that research will be required to support the detailed design and safety assessment in relation to any potentially detrimental interactions between the different modules. Different disposal system designs and associated Engineered Barrier Systems (EBS) will be required for these different waste types, i.e. ILW/LLW and HLW/SF. If declared as waste U would be disposed as ILW and Pu as HLW/SF. The Geological Disposal Facility (GDF) would therefore comprise two co-located modules (respectively for ILW/LLW and HLW/SF). A study has recently been undertaken by NDA RWMD to identify the key Thermo-Hydro-Mechanical-Chemical (THMC) interactions which might occur during both the operational and post-closure phases in order to assess the potential implications of co-location in a range of host rocks. This paper presents supporting modelling work used to help understand the potential interactions between the modules. A multi-phase flow and coupled gas generation model was used to help investigate the potential groundwater and gas fluxes between the modules, in particular considering the operational phase and resaturation behaviour of the different modules. These early phases are important because gas generation rates and hydraulic gradients will be at their maximum, and the pressure gradients associated with GDF operations will, at least initially, dominate over the background hydraulic gradient. The gas generation and multi-phase flow study considered a mudstone host rock in which gas pressurisation might significantly influence resaturation behaviour, or drive water from one module to the other. The results of the multiphase flow modelling show that although gas generation affects pressure recovery in the ILW/LLW module, the smaller size of the HLW/SF excavations compared with the ILW/LLW excavations, and the operational timings, mean that in general the groundwater pressure gradient in the GDF is from the HLW/SF module (higher pressure) to the ILW module (lower pressure). Transport of solutes from the HLW/SF module towards the ILW module is not expected to result in any deleterious interactions, indicating that hydraulic interactions during the resaturation period are unlikely to pose a fundamental barrier to co-location.

Study on Mechanical Influence of Gas Generation and Migration on Engineered Barrier System in Radioactive Waste Disposal Facility

2010 ◽  
Author(s):  
Mamoru Kumagai ◽  
Shuichi Yamamoto ◽  
Kunifumi Takeuchi ◽  
Yukihisa Tanaka ◽  
Michihiko Hironaga
Keyword(s):  
Radioactive Waste ◽  
Time Evolution ◽  
Mechanical Stability ◽  
Water Saturation ◽  
Hydrogen Gas ◽  
Gas Pressure ◽  
Radioactive Waste Disposal ◽  
Gas Generation ◽  
Disposal Facility ◽  
Engineered Barriers

In Japan, some radioactive waste with a relatively higher radioactivity concentration from nuclear facilities is to be packaged in rectangle steel containers and disposed of in subsurface disposal facilities, where normal human intrusion rarely occurs. After the closure of a facility, its pore is saturated with groundwater. If the dissolved oxygen of the pore water is consumed by steel corrosion, hydrogen gas will be generated from the metallic waste, steel containers, and reinforcing bars of concrete mainly by anaerobic corrosion. If the generated gas accumulates and the gas pressure increases excessively in the facility, the facility’s barrier performance might be degraded by mechanical influences such as crack formation in cementitious material or deformation of bentonite material. Firstly, in this study, we assessed the time evolution of the gas pressure and the water saturation in a sub-surface disposal facility by using a multi-phase flow numerical analysis code, GETFLOWS, in which a pathway dilation model is introduced and modified in order to reproduce the gas migration mechanism through the highly compacted bentonite. Next, we calculated the stress applied to the engineered barriers of the facility from the results of the time evolution of the pressure and the saturation. Then, we conducted a mechanical stability analysis of the engineered barriers by using a nonlinear finite element code, ABAQUS, in order to evaluate their performances after the closure of the facility.

Evaluation of the impact of multi-phase flow on reservoir signatures in the Wolfcamp shale

2020 ◽  
Vol 76 ◽  
pp. 103187
Author(s):  
C.R. Clarkson ◽  
B. Yuan ◽  
Z. Zhang ◽  
F. Tabasinejad ◽  
H. Behmanesh ◽  
...  
Keyword(s):  
Phase Flow ◽  
Multi Phase Flow ◽  
Multi Phase ◽  
The Impact

scholarly journals Global existence of solutions for a multi-phase flow: A drop in a gas-tube

2016 ◽  
Vol 13 (02) ◽  
pp. 381-415
Author(s):  
Debora Amadori ◽  
Paolo Baiti ◽  
Andrea Corli ◽  
Edda Dal Santo
Keyword(s):  
Global Existence ◽  
Existence Of Solutions ◽  
Inviscid Fluid ◽  
Phase Flow ◽  
Lagrangian Coordinates ◽  
Large Initial Data ◽  
Initial Value ◽  
Global Existence Of Solutions ◽  
Multi Phase Flow ◽  
Multi Phase

In this paper we study the flow of an inviscid fluid composed by three different phases. The model is a simple hyperbolic system of three conservation laws, in Lagrangian coordinates, where the phase interfaces are stationary. Our main result concerns the global existence of weak entropic solutions to the initial-value problem for large initial data.

scholarly journals Study of Multi-phase Flow in Porous Media: Comparison of SPH Simulations with Micro-model Experiments

2015 ◽  
Vol 114 (2) ◽  
pp. 581-600 ◽  
Author(s):  
P. Kunz ◽  
I. M. Zarikos ◽  
N. K. Karadimitriou ◽  
M. Huber ◽  
U. Nieken ◽  
...  
Keyword(s):  
Porous Media ◽  
Flow In Porous Media ◽  
Phase Flow ◽  
Micro Model ◽  
Model Experiments ◽  
Media Comparison ◽  
Multi Phase Flow ◽  
Multi Phase
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