Monte Carlo method for determining radon diffusion coefficients in porous media

Feng, Shaokong; Wang, Hanqing; Cui, Yu Jun; Ye, Yongjun; Li, Xiangyang; Xie, De; He, Zhengzhong; Yang, Rong

doi:10.1016/j.radmeas.2019.106130

Cited by 23 publications

(4 citation statements)

References 29 publications

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“…9) for all the three bentonite specimens with different saturations can be divided into two parts, including the intra-aggregate pores (micro-pores) having a diameter less than 137 nm, and the inter-aggregate pores (macro-pores) having a diameter larger than 137 nm. Therefore, in the micro-pores, "transition diffusion" is dominated, while in the macro-pores, "Fick diffusion" plays an important role (Feng et al 2019;Wang et al 2017). Meanwhile, curves in Figs.…”

Section: Effects Of Initial Saturation On Gas Diffusionmentioning

confidence: 96%

Gas diffusion property of compacted GMZ bentonite with consideration of saturation and gas pressure

Ye,

Ji,

et al. 2024

Preprint

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During the long-term operation of a deep geological repository, hydrogen, methane and carbon dioxide, etc. could be generated and accumulated in bentonite around canisters, threatening integrity and safety of engineering barrier systems. In this work, self-designed test apparatuses were developed. Gas diffusion tests were conducted on GMZ bentonite specimens under both rigid and flexible boundary conditions with consideration of initial saturations and gas pressures. After experienced the gas diffusion tests, the specimens were cut and submitted for the mercury intrusion porosimetry (MIP) tests. Results revealed that gas diffusion coefficient was obviously influenced by the initial saturations and gas pressures. As gas pressure increased from 1 to 4 MPa, a decrease of 55.3% ~ 58.8% and 17.7% ~ 73.4% in the diffusion coefficient were recorded for the specimens tested under rigid and flexible boundary, respectively. Compared to the rigid boundary conditions, the effective pore volume for gas molecule diffusion was further compressed under flexible boundary, resulting in a relatively poor pore connectivity and a lower gas diffusion coefficient. Meanwhile, the diffusion coefficient decreased with increasing initial saturations for the flexible boundary specimens, while an opposite trend was recorded for the rigid boundary ones. Explanations to this observation could be that under the rigid boundary conditions, specimens with higher initial saturations have larger diameter macro-pores, facilitating the gas diffusion.

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Section: Effects Of Initial Saturation On Gas Diffusionmentioning

confidence: 96%

Gas diffusion property of compacted GMZ bentonite with consideration of saturation and gas pressure

Ye,

Ji,

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…To reduce subjectivity and possible biases, a large number of replicated runs is suggested when conducting a Monte Carlo analysis [123], and several studies have recommended to run 10,000 replications [124,125]. That being said, and since the developed ABM in this research includes different uncertainties, the model was integrated with Monte Carlo analysis that was performed for 10,000 runs.…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

Optimal Preventive Maintenance, Repair, and Replacement Program for Catch Basins to Reduce Urban Flooding: Integrating Agent-Based Modeling and Monte Carlo Simulation

Assaf

Assaad

2023

Sustainability

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Urban sprawl has resulted in great losses of vegetation areas, an increase in impervious surfaces, and consequently the direct flow of stormwater into stream channels (i.e., the immediate flow of stormwater into stream channels, in comparison to the indirect flow that is represented by practices aiming to retain stormwater for a certain period of time and treat the polluted stormwater prior to flowing into the stream channels such as detention/retention basins, among others). Stormwater management systems such as catch basins (CBs) are needed to reduce the effect of stormwater runoff. Preventative maintenance, repair, and replacement of CBs are critical to achieve stormwater management best practices. Those practices prevent the blockage of the stormwater system, limit the pollutants in storm sewers, and reduce the risk of flooding. However, no preceding research studies have been conducted to model and simulate the serviceability of CBs and to determine optimal strategies for operating CBs. To that extent, this study establishes a framework to develop and validate an optimal and adaptive maintenance, repair, and overhaul (MRO) strategy for CBs. In relation to that, an agent-based model (ABM) integrated with Monte Carlo simulation was developed for all 560 CBs in New York City’s District 5 and was statistically validated using 99% confidence intervals. The MRO parameters were optimized to minimize the total cost of the system and attain the desired level of serviceability of CBs. Sensitivity analysis was conducted to guide the maintenance planning process of CBs and reveal the effect of the input parameters on the model’s behavior. In addition, ten thousand Monte Carlo iterations were simulated to derive the distributions of the defined parameters. The results proved that in order to minimize the overall cost of repair, maintenance, and replacement of CBs and attain a minimum serviceability threshold of 80%, the following optimal MRO policy needs to be implemented: having seven service crews (where service crews are human resources (i.e., MRO teams) needed to perform the required maintenance, repair, and replacement work), implementing a replacing policy, and replacing CBs after five maintenance periods. The findings revealed that the service crews represent the most critical parameter in affecting the total cost and serviceability of CBs. This research contributes to the existing literature by offering a better knowledge of the management process of CBs and devising optimal MRO strategies for properly operating them. Ultimately, this research helps decision-makers and engineers increase the lifespan of CBs and limit their risks of breakdown, increase their efficiency, and avoid unnecessary costs. The proposed model is flexible and can be implemented to any geographical area and with other model/system parameters, which makes it adaptive for any scenario and area presented by the user. Finally, maintaining stormwater management practices helps in protecting the environment by decreasing the demand on stormwater systems, reducing flooding, protecting people and properties, promoting healthier rivers, and consequently creating more sustainable communities.

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“…A RAD7 radon meter ) was used to measure the accumulated radon concentration of solidified samples via closed chamber method (Feng, et al 2019) (Fig. 4).…”

Section: Radon Exhalation Testmentioning

confidence: 99%

Physical-mechanical Properties and Radon Exhalation of Fiber-reinforced Uranium Tailings Geopolymer Solidified Bodies

Jiang

Tan

Wang

et al. 2021

Preprint

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Uranium tailing ponds are a potential major source of radioactive pollution. Solidification treatment of uranium tailings can control the diffusion and migration of radioactive elements in uranium tailings to safeguard the surrounding ecological environment. Literature review and field investigation were conducted in this study prior to fabricating 11 solidified uranium tailings samples with different proportions with PVA fiber, basalt fiber, metakaolin, and fly ash. The samples’ pore structure, volume resistivity, compressive strength, and radon exhalation rate variations were analyzed. The pore size of the solidified samples is mainly between 1–50 nm, the pore volume is between 0.726–1.750 cm3/g, the volume resistivity is between 1411.33-1937.33 Ω·m, and the compressive strength is between 20.61–36.91 MPa. The radon exhalation rate is between 0.0397–0.0853 Bq·m2·s− 1, which is lower than the national standard. Based on a comprehensive analysis of the physical and mechanical properties and radon exhalation rate of the solidified samples, the basalt fiber is found to outperform PVA fiber overall. The solidification effect is optimal when the 0.6% basalt fiber is added.

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Monte Carlo method for determining radon diffusion coefficients in porous media

Cited by 23 publications

References 29 publications

Gas diffusion property of compacted GMZ bentonite with consideration of saturation and gas pressure

Gas diffusion property of compacted GMZ bentonite with consideration of saturation and gas pressure

Optimal Preventive Maintenance, Repair, and Replacement Program for Catch Basins to Reduce Urban Flooding: Integrating Agent-Based Modeling and Monte Carlo Simulation

Physical-mechanical Properties and Radon Exhalation of Fiber-reinforced Uranium Tailings Geopolymer Solidified Bodies

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