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University of Notre Dame

1. Nancy Elaine Roback. Crystal Chemistry of Uranyl Sulfates and Oxalates and Perrhenate Incorporation into Uranyl Phases</h1>.

Degree: MS, Chemistry and Biochemistry, 2009, University of Notre Dame

The understanding of uranium chemistry is of increasing importance in the search for clean, renewable energy. Nuclear power can produce energy with no greenhouse gas emissions and far fewer raw materials. One ton of uranium produces power equivalent to 16,000 tons of coal or 80,000 barrels of oil (Nuclear Energy Institute, 2009). However, controversy surrounds nuclear power due to the disposal of spent nuclear fuel. There is currently no long-term storage facility in the United States. Yucca Mountain, Nevada has been proposed as a geological repository, but more information on the chemistry of spent fuel components, such as uranium and technetium is needed to ensure safety and secure a license for operation. This research expands the knowledge of uranium crystal chemistry and the ability of uranyl phases to incorporate components of spent nuclear fuel. A novel new uranyl sulfate and three new uranyl oxalate compounds are presented, along with a study of the incorporation of perrhenate (ReO4-), as a analog for pertechnetate (TcO4 ), into uranyl phases. The uranyl sulfate K2[(UO2)(SO4)2H2O]H2O crystallized in the Cmca space group and is composed of uranyl pentagonal bipyramids linked into infinite chains with sulfate tetrahedra. The uranyl oxalate Cs2(UO2)2(C2O4)3 crystallized in the P21 space group and is composed of infinite sheets of uranyl pentagonal bipyramids connected via oxalate ions. The uranyl oxalate hydroxide Cs(UO2)2(C2O4)(OH)3 crystallized in the P21/m space group and is composed of infinite sheets of uranyl pentagonal bipyramids connected via oxalate ions and edge sharing polyhedra. The uranyl oxalate K6(UO2)2(C2O4)4O2 crystallized in the space group P21/c. It is composed of isolated clusters of two uranyl hexagonal bipyramids connected via edge sharing and contains a total of four coordinated oxalate ions. All crystals were analyzed with single crystal x-ray diffraction. The structures were solved with SHELL XL software. Technetium-99 is an important dose contributor in a geological repository (Burns et al., 1997a; Chen et al., 2000). It is a potentially mobile component of spent nuclear fuel with a relatively long half-life. The uranyl mineral analogues, uranophane, Ca[(UO2)(SiO3OH)]2Ì¢�âÂå¢5H2O, sodium boltwoodite, Na(UO2)(SiO3OH)Ì¢�âÂå¢1.5H2O, and soddyite, (UO2)2(SiO4)Ì¢�âÂå¢2H2O, are known to form from spent nuclear fuel and are expected to form in a geologic repository (Finch and Ewing, 1992; Wronkiewicz et al., 1996). The extent to which Tc7+, found as pertechnetate (TcO4-), is incorporated into these uranyl phases will impact its mobility in the repository (Burns et al., 1997a; Chen et al., 2000). In this research, the above uranyl phases were hydrothermally synthesized in the presence of perrhenate (ReO4-), as a crystal chemical analog for pertechnetate (TcO4 ). The identity of the uranyl phases were verified with powder x-ray diffraction. The presence of rhenium was analyzed using inductively coupled plasma Ì¢�âÂ" optical emission spectroscopy… Advisors/Committee Members: Peter Burns, Committee Member, Kenneth Henderson, Committee Member, Marya Lieberman, Committee Member, Slavi Sevov, Committee Member.

Subjects/Keywords: technetium; sulfate; uranium; perrhenate; crystal chemistry; nuclear waste; oxalate; pertechnetate; rhenium; inorganic; chemistry; uranyl

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Roback, N. E. (2009). Crystal Chemistry of Uranyl Sulfates and Oxalates and Perrhenate Incorporation into Uranyl Phases</h1>. (Masters Thesis). University of Notre Dame. Retrieved from https://curate.nd.edu/show/hx11xd09p9j

Chicago Manual of Style (16th Edition):

Roback, Nancy Elaine. “Crystal Chemistry of Uranyl Sulfates and Oxalates and Perrhenate Incorporation into Uranyl Phases</h1>.” 2009. Masters Thesis, University of Notre Dame. Accessed June 20, 2019. https://curate.nd.edu/show/hx11xd09p9j.

MLA Handbook (7th Edition):

Roback, Nancy Elaine. “Crystal Chemistry of Uranyl Sulfates and Oxalates and Perrhenate Incorporation into Uranyl Phases</h1>.” 2009. Web. 20 Jun 2019.

Vancouver:

Roback NE. Crystal Chemistry of Uranyl Sulfates and Oxalates and Perrhenate Incorporation into Uranyl Phases</h1>. [Internet] [Masters thesis]. University of Notre Dame; 2009. [cited 2019 Jun 20]. Available from: https://curate.nd.edu/show/hx11xd09p9j.

Council of Science Editors:

Roback NE. Crystal Chemistry of Uranyl Sulfates and Oxalates and Perrhenate Incorporation into Uranyl Phases</h1>. [Masters Thesis]. University of Notre Dame; 2009. Available from: https://curate.nd.edu/show/hx11xd09p9j

2. [No author]. The role of secondary aluminosilicate minerals in technetium-99 immobilization in radioactive waste .

Degree: 2014, Washington State University

Corroding waste tanks at select U.S. Department of Energy's nuclear waste facility have leaked highly alkaline tank waste solutions containing radionuclides and other contaminants into subsurface sediments. These tank wastes react with subsurface sediments to form secondary mineral phase(s) (feldspathoids), which may play key role in the transport of contaminants through the vadose zone and aquifers. Although transformation of secondary precipitates in subsurface sediments has been extensively studied, however, there is lack of knowledge about the role of feldspathoid selectivity in controlling the long-term fate and transport of key anionic radionuclides in the subsurface. The overarching objectives of this dissertation were to (1) determine secondary mineral transformation with aging time, alkalinity, anion identity and selectivity, and (2) quantify the competitive incorporation of ReO4⁻ (a chemical analogue for Tc-99) into mineral phase(s) as a function of anion composition, size and selectivity under simulated waste leaks. The key results of this work showed that alkalinity, time and anion composition play important role in mineral transformation that control the mobility of key radionuclide species in the environment. Nitrite and chloride anions predominantly promote sodalite phase(s) formation. Nitrate in high NaOH solution favored cancrinite phase(s) while in low NaOH fostered mixed cancrinite/sodalite phase(s) formation. The sequestering capacity of sodalite for ReO4⁻ was ~5 times higher than that of cancrinite. The immobilized ReO4⁻ in the sodalite cages was not easily exchangeable with other competing anions. Due to the less distortion to the β-cage, sodalite displayed stronger preference for smaller competing anions relative to the larger ReO4⁻ anion. The selectivity of the mixed sodalite cage for ReO4⁻ was largely driven by the difference in anion radii (DIR) and increases in the series as follows: Cl⁻<CO₃²⁻<NO₃⁻<SO₄²⁻<<MnO₄⁻<WO₄²⁻. Similar valency and DIR of ≤15% facilitate significant ReO4⁻ immobilization into sodalite β-cages. Advisors/Committee Members: Harsh, James B (advisor).

Subjects/Keywords: Geochemistry; Environmental science; Nuclear chemistry; anion competition; zeolite; cancrinite; sodalite; technetium; perrhenate; selectivity; incorporation; feldspathoids; waste tanks; caustic solution; remediation; feldspathoids

Perrhenate Incorporation into Binary Mixed Sodalites… …52 Immobilization and Exchange of Perrhenate in… …67 4.3.2 Perrhenate exchange with NO2− and NO3… …objectives are: 1. To quantify the extent of ReO4− incorporation into mixed perrhenate/nitrate… …W.W.; Pierce, E.M. (2014), Competitive incorporation of perrhenate and nitrate… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

author], [. (2014). The role of secondary aluminosilicate minerals in technetium-99 immobilization in radioactive waste . (Thesis). Washington State University. Retrieved from http://hdl.handle.net/2376/5191

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

author], [No. “The role of secondary aluminosilicate minerals in technetium-99 immobilization in radioactive waste .” 2014. Thesis, Washington State University. Accessed June 20, 2019. http://hdl.handle.net/2376/5191.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

author], [No. “The role of secondary aluminosilicate minerals in technetium-99 immobilization in radioactive waste .” 2014. Web. 20 Jun 2019.

Vancouver:

author] [. The role of secondary aluminosilicate minerals in technetium-99 immobilization in radioactive waste . [Internet] [Thesis]. Washington State University; 2014. [cited 2019 Jun 20]. Available from: http://hdl.handle.net/2376/5191.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

author] [. The role of secondary aluminosilicate minerals in technetium-99 immobilization in radioactive waste . [Thesis]. Washington State University; 2014. Available from: http://hdl.handle.net/2376/5191

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.