APPLICATION OF MULTI-GROUP DIFFUSION THEORY TO MECHANISTIC MODELLING OF LEACHING BEHAVIOR OF SOLIDIFIED LOW-LEVEL RADIOACTIVE WASTE FORMS.

Persistent Link:
http://hdl.handle.net/10150/184088
Title:
APPLICATION OF MULTI-GROUP DIFFUSION THEORY TO MECHANISTIC MODELLING OF LEACHING BEHAVIOR OF SOLIDIFIED LOW-LEVEL RADIOACTIVE WASTE FORMS.
Author:
NIMNUAL, SOMKID.
Issue Date:
1987
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The application of multi-concentration group mathematical modelling to the leaching of radionuclide waste-forms which have continuous porous matrix such as cemented waste form is described. The modelling is illustrated analysing a hypothetical of some transport mechanisms such as molecular diffusion, ionic migration and convective flow for release of interest radionuclide from a solidified waste form which contains discrete particles of radioactive Sr-85 nuclides into the aqueous environment. The group parameters are derived from the classical electrochemistry concept of ion transport in dilute electrolytic solution. The numerical analysis is based on the Crank-Nicolson Implicit Methods which assures the stability of the solution at a practical time step. The results show that, for a short-time period of leaching in demineralized water the leaching behavior follows the predominating diffusion mechanism. After this point, the role of other processes apparent and continue until all radionuclides in the cement waste are leached out when compared to the Semi-Infinite Diffusion model which is based on pure diffusion mechanism. The multi-concentration group model can also be applied to long-term prediction of complicated release mechanisms of the radionuclides in the waste form of a particular disposal environment, unless the variables of interest such as the corrosion rate, the chemical reaction, erosion rate and etc. are determined by experiment or theoretical hypothesis. The appropriate differential equation then can be solved by the same general numerical approach. Also, the results of the modelling indicate which parameters should be measured experimentally in order to provide a quantitative test of the hypothetical release mechanism.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Low-level radiation.; Radioactive wastes.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Nuclear and Energy Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Wacks, M. E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleAPPLICATION OF MULTI-GROUP DIFFUSION THEORY TO MECHANISTIC MODELLING OF LEACHING BEHAVIOR OF SOLIDIFIED LOW-LEVEL RADIOACTIVE WASTE FORMS.en_US
dc.creatorNIMNUAL, SOMKID.en_US
dc.contributor.authorNIMNUAL, SOMKID.en_US
dc.date.issued1987en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe application of multi-concentration group mathematical modelling to the leaching of radionuclide waste-forms which have continuous porous matrix such as cemented waste form is described. The modelling is illustrated analysing a hypothetical of some transport mechanisms such as molecular diffusion, ionic migration and convective flow for release of interest radionuclide from a solidified waste form which contains discrete particles of radioactive Sr-85 nuclides into the aqueous environment. The group parameters are derived from the classical electrochemistry concept of ion transport in dilute electrolytic solution. The numerical analysis is based on the Crank-Nicolson Implicit Methods which assures the stability of the solution at a practical time step. The results show that, for a short-time period of leaching in demineralized water the leaching behavior follows the predominating diffusion mechanism. After this point, the role of other processes apparent and continue until all radionuclides in the cement waste are leached out when compared to the Semi-Infinite Diffusion model which is based on pure diffusion mechanism. The multi-concentration group model can also be applied to long-term prediction of complicated release mechanisms of the radionuclides in the waste form of a particular disposal environment, unless the variables of interest such as the corrosion rate, the chemical reaction, erosion rate and etc. are determined by experiment or theoretical hypothesis. The appropriate differential equation then can be solved by the same general numerical approach. Also, the results of the modelling indicate which parameters should be measured experimentally in order to provide a quantitative test of the hypothetical release mechanism.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectLow-level radiation.en_US
dc.subjectRadioactive wastes.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineNuclear and Energy Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWacks, M. E.en_US
dc.identifier.proquest8712902en_US
dc.identifier.oclc698474691en_US
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