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Intercomparison of diffusion coefficient derived from the through-diffusion experiment using different numerical methods.

Chen CL, Wang TH, Lee CH, Teng SP - J Radioanal Nucl Chem (2014)

Bottom Line: Diffusion is a dominant mechanism regulating the transport of released nuclides.The combinations involve four distinct models (i.e., the CC-CC model, CC-VC model, VC-CC model, and the VC-VC model).Studies discussing the VC-CC model are scant.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan ; Division of Chemical Engineering, Institute of Nuclear Energy Research, Taoyuan, Taiwan.

ABSTRACT

Diffusion is a dominant mechanism regulating the transport of released nuclides. The through-diffusion method is typically applied to determine the diffusion coefficients (D). Depending on the design of the experiment, the concentrations in the source term [i.e., inlet reservoir (IR)] or the end term [i.e., outlet reservoir (OR)] can be fixed or vary. The combinations involve four distinct models (i.e., the CC-CC model, CC-VC model, VC-CC model, and the VC-VC model). Studies discussing the VC-CC model are scant. An analytical method considering the decay effect is required to accurately interpret the radioactive nuclide diffusion experiment results. Therefore, we developed a CC-CC model and a CC-VC model with a decay effect and the simplified formulas of these two models to determine the diffusion coefficient (i.e., the CC-CC method and CC-VC method). We also proposed two simplified methods using the VC-VC model to determine the diffusion coefficient straightforwardly based upon the concentration variation in IR and OR. More importantly, the best advantage of proposed method over others is that one can derive three diffusion coefficients based on one run of experiment. In addition, applying our CC-VC method to those data reported from Radiochemica Acta 96:111-117, 2008; and J Contam Hydrol 35:55-65, 1998, derived comparable diffusion coefficient lying in the identical order of magnitude. Furthermore, we proposed a formula to determine the conceptual critical time (Tc), which is particularly beneficial for the selection of using CC-VC or VC-VC method. Based on our proposed method, it becomes possible to calculate diffusion coefficient from a through-diffusion experiment in a shorter period of time.

No MeSH data available.


Related in: MedlinePlus

The Case_D+ concentration distribution in the OR of CC–CC, CC–VC and VC–VC models
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Fig7: The Case_D+ concentration distribution in the OR of CC–CC, CC–VC and VC–VC models

Mentions: With a higher diffusion coefficient (Case_D+), the concentration distributions in the OR seem to depart from each numerical experiment (Fig. 7). After arranging for linear regression against time, the differences are obvious between each experiment (Fig. 8). A higher deviation obtained using an unsuitable analysis method is displayed clearly, as shown in Table 6.Fig. 7


Intercomparison of diffusion coefficient derived from the through-diffusion experiment using different numerical methods.

Chen CL, Wang TH, Lee CH, Teng SP - J Radioanal Nucl Chem (2014)

The Case_D+ concentration distribution in the OR of CC–CC, CC–VC and VC–VC models
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4514585&req=5

Fig7: The Case_D+ concentration distribution in the OR of CC–CC, CC–VC and VC–VC models
Mentions: With a higher diffusion coefficient (Case_D+), the concentration distributions in the OR seem to depart from each numerical experiment (Fig. 7). After arranging for linear regression against time, the differences are obvious between each experiment (Fig. 8). A higher deviation obtained using an unsuitable analysis method is displayed clearly, as shown in Table 6.Fig. 7

Bottom Line: Diffusion is a dominant mechanism regulating the transport of released nuclides.The combinations involve four distinct models (i.e., the CC-CC model, CC-VC model, VC-CC model, and the VC-VC model).Studies discussing the VC-CC model are scant.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan ; Division of Chemical Engineering, Institute of Nuclear Energy Research, Taoyuan, Taiwan.

ABSTRACT

Diffusion is a dominant mechanism regulating the transport of released nuclides. The through-diffusion method is typically applied to determine the diffusion coefficients (D). Depending on the design of the experiment, the concentrations in the source term [i.e., inlet reservoir (IR)] or the end term [i.e., outlet reservoir (OR)] can be fixed or vary. The combinations involve four distinct models (i.e., the CC-CC model, CC-VC model, VC-CC model, and the VC-VC model). Studies discussing the VC-CC model are scant. An analytical method considering the decay effect is required to accurately interpret the radioactive nuclide diffusion experiment results. Therefore, we developed a CC-CC model and a CC-VC model with a decay effect and the simplified formulas of these two models to determine the diffusion coefficient (i.e., the CC-CC method and CC-VC method). We also proposed two simplified methods using the VC-VC model to determine the diffusion coefficient straightforwardly based upon the concentration variation in IR and OR. More importantly, the best advantage of proposed method over others is that one can derive three diffusion coefficients based on one run of experiment. In addition, applying our CC-VC method to those data reported from Radiochemica Acta 96:111-117, 2008; and J Contam Hydrol 35:55-65, 1998, derived comparable diffusion coefficient lying in the identical order of magnitude. Furthermore, we proposed a formula to determine the conceptual critical time (Tc), which is particularly beneficial for the selection of using CC-VC or VC-VC method. Based on our proposed method, it becomes possible to calculate diffusion coefficient from a through-diffusion experiment in a shorter period of time.

No MeSH data available.


Related in: MedlinePlus