Gas Migration in Low- and Intermediate-Level Waste (LILW) Disposal Facility in Korea

2013 ◽  
Author(s):  
Jae-Chul Ha ◽  
Jeong-Hwan Lee ◽  
Haeryong Jung ◽  
Juyub Kim ◽  
Juyoul Kim
Keyword(s):  
Gas Permeability ◽  
Hydrogen Gas ◽  
Intermediate Level ◽  
Gas Migration ◽  
Gas Generation ◽  
Reference Case ◽  
Disposal Facility ◽  
Entry Pressure ◽  
Under Construction ◽  
Different Gases

The first low- and intermediate-level waste (LILW) disposal facility is under construction in saturated granite in Korea. The safety assessment report (SAR) identified that different gases, such as hydrogen, carbon dioxide, and methane are generated at the disposal facility due to the corrosion of metal wastes and steel drum, and microbial degradation of organic matters. Reinforced concrete plays a role as an engineered barrier at the disposal facility, so its properties with regard to gas migration were evaluated in laboratory-scale experiments. Then modeling of gas migration was carried out to evaluate gas pressure build-up in the disposal facility. The gas entry pressure and relative gas permeability of the concrete was determined to be 0.97±0.15 bar, and the relative gas permeability decreased exponentially with increasing water content. The results of the modeling showed that most of hydrogen gas was dissolved in groundwater and did not significantly influence pressure build-up inside the disposal facility based on the reference case of gas generation.

scholarly journals Gas Migration in Low- and Intermediate-Level Waste (LILW) Disposal Facility in Korea

2014 ◽  
Vol 12 (4) ◽  
pp. 267-274
Author(s):  
Jaechul Ha ◽  
Jeong-Hwan Lee ◽  
Haeryong Jung ◽  
Juyub Kim ◽  
Juyoul Kim
Keyword(s):  
Intermediate Level ◽  
Gas Migration ◽  
Disposal Facility

Study on Gas Pressure Characteristics in Multi-Layered Landfills of Municipal Solid Waste

2012 ◽  
Vol 518-523 ◽  
pp. 3507-3511
Author(s):  
Fu Liang Mei ◽  
Gui Ling Li
Keyword(s):  
Pressure Distribution ◽  
Soil Cover ◽  
Gas Permeability ◽  
Gas Pressure ◽  
Generation Rate ◽  
Distribution Characteristics ◽  
Gas Migration ◽  
Gas Generation ◽  
Msw Landfill ◽  
Gas Generation Rate

In this treatise one-dimensional mathematical model of gas migration in multi-layered landfills of MSW on seepage mechanics of multi-pore media and Darcy’s seepage law. Analysis of gas migration in multi-layered landfills is carried out for three different cases. The gas pressure distribution characteristics in multi-layered landfills of MSW, the effects of final/internal soil cover, the permeability and thickness of the final soil cover, the permeability and gas generation rate of MSW on the gas pressure distributions are investigated. Results show that the bigger is the ratio of gas generation rate to gas permeability of MSW, the bigger is the gas pressure in a uniform MSW landfill. The gas generation rate of MSW mainly controls the size of gas pressure, and the gas permeability of MSW dominates the gas pressure distribution characteristics in a uniform MSW landfill with a final soil cover. The smaller is the gas permeability of the final soil cover or the bigger is the gas generation rate of MSW the bigger is the gas pressure gradient inside the final soil cover

Gas Migration Mechanism of Saturated Highly-Compacted Bentonite and Its Modeling

2010 ◽  
Author(s):  
Yukihisa Tanaka ◽  
Michihiko Hironaga ◽  
Koji Kudo
Keyword(s):  
Gaseous Phase ◽  
Gas Flow ◽  
Hydrogen Gas ◽  
Radioactive Waste Disposal ◽  
Gas Migration ◽  
Void Space ◽  
Gas Generation ◽  
Compacted Bentonite ◽  
Migration Mechanism ◽  
Engineered Barrier

In the current concept of repository for radioactive waste disposal, compacted bentonite will be used as an engineered barrier mainly for inhibiting migration of radioactive nuclides. Hydrogen gas can be generated inside the engineered barrier by anaerobic corrosion of metals used for containers, etc. If the gas generation rate exceeds the diffusion rate of gas molecules inside of the engineered barrier, gas will accumulate in the void space inside of the engineered barrier until its pressure becomes large enough for it to enter the bentonite as a discrete gaseous phase. It is expected to be not easy for gas to entering into the bentonite as a discrete gaseous phase because the pore of compacted bentonite is so minute. Therefore the gas migration tests are conducted in this study to investigate the mechanism of gas migration. On the basis of the experimental facts obtained through the gas migration tests, possible gas migration mechanism is proposed. A simplified method for calculating gas pressure at large breakthrough, which is defined as a sudden and sharp increase in gas flow rate out of the specimen is also proposed.

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.

Preliminary Test on Gas Migration Through Bentonite-Sand Mixture

1994 ◽  
Vol 353 ◽  
Author(s):  
T. Hokari ◽  
T. Ishii ◽  
T. Nagasawa ◽  
R. Tomita ◽  
M. Nakajima
Keyword(s):  
Hydraulic Conductivity ◽  
Gas Permeability ◽  
Preliminary Test ◽  
Gas Migration ◽  
Overburden Pressure ◽  
Sand Mixture ◽  
Groundwater Flux ◽  
Disposal Facility ◽  
Gas Volume ◽  
Breakthrough Pressure

AbstractThe Low-Level Radioactive Disposal facility [1] is planned to cover the vaults with impermeable bentonite-sand mixture in order to minimize groundwater flux through the facility. In case that metal wastes are to be disposed of in the burial facility in the future, it is essential to confirm that bentonite mixture should have gas permeability enough for the gas volume which would be expected to be generated due to an aerobic corrosion of metals[2]. This report performed a preliminary test with a bentonite-sand mixture whose aggregate was Japanese Standard sand. Results are the followings;(l)Gas breakthrough pressure of the mixture was less than the overburden pressure. The gas permeability was estimated to be of order of 10-2 md. (2)The mixture did not deteriorate in hydraulic conductivity after gas breakthrough.

The Gas Permeability of Plasma Sprayed Ceramic Coatings

1997 ◽  
Author(s):  
A.C. Fox ◽  
T.W. Clyne
Keyword(s):  
Gas Permeability ◽  
Test Procedure ◽  
Ceramic Coatings ◽  
Hydrogen Gas ◽  
Steady State Flow ◽  
Flow Rates ◽  
Specific Permeability ◽  
Measured Flow ◽  
Flow Through ◽  
Plasma Sprayed

Abstract A simple test procedure, based on steady state flow through a membrane, has been developed for measurement of the gas permeability of specimens over a range of temperature. The reliability of this equipment has been verified by testing solid disks containing single perforations and comparing the measured flow rates with those expected on the basis of laminar flow. Coatings of yttria-stabilised zirconia have been produced by plasma spraying in vacuum and in air. The specific permeability of these coatings has been measured at temperatures ranging up to 600°C, using hydrogen gas. It has been found that permeability is increased for coatings produced with longer stand-off distances and at higher pressures. Porosity levels have been measured using densitometry and microstructural features have been examined using SEM. A model has been developed for prediction of the permeability from such microstructural features, based on percolation theory. Agreement between predicted and measured permeabilities is good, although it is clear that more comprehensive data are needed in order to validate the model systematically.

Sign in / Sign up

Export Citation Format

Share Document