Studies of the effects of chelates on the leaching of radionuclides from cement.

Persistent Link:
http://hdl.handle.net/10150/185491
Title:
Studies of the effects of chelates on the leaching of radionuclides from cement.
Author:
Ferrara, Daro Mitchell.
Issue Date:
1991
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:
To evaluate the release of some important radionuclides from cement waste forms, a variety of studies have been completed. Leach rates and equilibrium concentrations of some complexing agents and radionuclides were measured, and the effect of a simulated waste form on these values was determined. Complexing agent concentrations were evaluated. Tests in deionized water showed ethylenediaminetetraacetic acid (EDTA) was leached from a simulated waste form more rapidly than nitrilotriacetic acid (NTA) which was released more rapidly than citric acid. Equilibrium concentrations were measured in deionized water, saturated sodium chloride, 24% magnesium chloride and Q-brine which is a simulated groundwater based on magnesium chloride. At equilibrium, the EDTA release fraction was independent of the amount of EDTA in the cement. The citric acid concentration was constant at less than 10⁻⁵ M. Finally, NTA concentrations and release fractions were both dependent on the cement loading. To evaluate the effect of complexing agents on some radionuclides, leach rates of cesium and cobalt and equilibrium concentrations of cobalt and uranium were studied. The effects of EDTA, NTA and citric acid on release rates of cesium and cobalt were studied, and the effects of several complexing agents on the equilibrium concentrations of cobalt and uranium were examined. Complexing agents had no effect on cesium leach rates. In water and in sodium chloride, cobalt and uranium concentrations in the presence of cement did not vary with any complexing agent. In Q-brine in the presence of cement, tartaric acid, EDTA and NTA increased the soluble cobalt concentration two orders of magnitude, and citric acid had a much smaller effect. Uranium concentrations in Q-brine were increased in EDTA, tartaric acid and citric acid when cement was in the system.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic; Nuclear engineering.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Nuclear and Energy Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Wacks, Morton E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleStudies of the effects of chelates on the leaching of radionuclides from cement.en_US
dc.creatorFerrara, Daro Mitchell.en_US
dc.contributor.authorFerrara, Daro Mitchell.en_US
dc.date.issued1991en_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.abstractTo evaluate the release of some important radionuclides from cement waste forms, a variety of studies have been completed. Leach rates and equilibrium concentrations of some complexing agents and radionuclides were measured, and the effect of a simulated waste form on these values was determined. Complexing agent concentrations were evaluated. Tests in deionized water showed ethylenediaminetetraacetic acid (EDTA) was leached from a simulated waste form more rapidly than nitrilotriacetic acid (NTA) which was released more rapidly than citric acid. Equilibrium concentrations were measured in deionized water, saturated sodium chloride, 24% magnesium chloride and Q-brine which is a simulated groundwater based on magnesium chloride. At equilibrium, the EDTA release fraction was independent of the amount of EDTA in the cement. The citric acid concentration was constant at less than 10⁻⁵ M. Finally, NTA concentrations and release fractions were both dependent on the cement loading. To evaluate the effect of complexing agents on some radionuclides, leach rates of cesium and cobalt and equilibrium concentrations of cobalt and uranium were studied. The effects of EDTA, NTA and citric acid on release rates of cesium and cobalt were studied, and the effects of several complexing agents on the equilibrium concentrations of cobalt and uranium were examined. Complexing agents had no effect on cesium leach rates. In water and in sodium chloride, cobalt and uranium concentrations in the presence of cement did not vary with any complexing agent. In Q-brine in the presence of cement, tartaric acid, EDTA and NTA increased the soluble cobalt concentration two orders of magnitude, and citric acid had a much smaller effect. Uranium concentrations in Q-brine were increased in EDTA, tartaric acid and citric acid when cement was in the system.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academicen_US
dc.subjectNuclear engineering.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, Morton E.en_US
dc.contributor.committeememberFreiser, Henryen_US
dc.contributor.committeememberDenton, M.B.-
dc.identifier.proquest9127708en_US
dc.identifier.oclc710835114en_US
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