Award Date

5-1-2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry and Biochemistry

First Committee Member

Kenneth Czerwinski

Second Committee Member

Daniel Koury

Third Committee Member

Frederic Poineau

Fourth Committee Member

William Culbreth

Number of Pages

225

Abstract

Melt glass formed from the explosion of a nuclear device is a unique post-detonation material that can aid in the ensuing forensics investigation. Trapped in the melt glass are chemical and isotopic signatures that can provide diagnostic and source information about the weapon by comparison with documentation of previous detonations. A nuclear terrorist attack would likely take place in an urban environment and as such, the melt glass formed would consist of a complex matrix including urban materials like cement and glass, activation products from the large neutron flux that will be seen, and fission products from the detonation. The preparation and study of a synthetic urban melt glass can aid in the understanding and analysis of real-world samples by being able to properly devise analysis protocols. In this dissertation, synthetic melt glass and synthetic urban melt glass are prepared. Each melt glass matrix is studied for its interactions with iron and uranium species. Elements that are of interest as forensics markers that can be doped into a synthetic urban melt glass are investigated for their extraction characteristics on TRU resin. As many radiochemical analysis methods require a sample to be in solution, dissolution methods for synthetic urban melt glass are also studied.

A silicon dioxide-based synthetic melt glass matrix modeled on the standard reference material SRM612 is synthesized. Based upon studies of the debris analyzed in the wake of the collapse of the World Trade Center, a synthetic urban melt glass is manufactured with a 1:1 mass ratio of glass and cement. The synthetic glass matrices are created in both monolith and pellet form. The interactions of iron and uranium species with synthetic melt glass and synthetic urban melt glass are studied with diffusion couples in oxidizing, inert, and reducing atmospheric conditions over a range of temperatures. The species Fe, FeO, Fe3O4, Fe2O3, U, UO2, UO3, and U3O8 are studied to understand how initial speciation of elements can impact the melt glass product. Both the atmosphere and the iron or uranium species has an impact on the reactions with the synthetic melt glass matrices. For some of the interfaces and conditions studied, activation energies of the iron or uranium diffusion into the glass matrix are determined. The formation of fayalite, Fe2SiO4, and a uranium-silicate species by chemical reaction leads to the appearance of non-Arrhenius diffusion behavior from reaction fronts that prevent activation energies from being determined for all conditions, studies with larger temperature ranges would make it possible to exclude these outliers.

The adsorption characteristics of gold, iridium, platinum, and tungsten on the extraction chromatography TRU resin, hydrochloric and nitric acid are examined. These elements are of interest for their incorporation in synthetic melt glass to order to study and separate gold, iridium, and tungsten, from their respective (n, p) activation products platinum, osmium, and tantalum. In the conditions studied, only gold and tungsten exhibited any significant sorption to TRU resin. Separation schemes of these elements are possible with a TRU column, adjusting the matrix to elute one element at a time.

The complex matrix of synthetic urban melt glass will inhibit traditional dissolution methods like acid digestion. As such, microwave digestion, salt fusion, and sequential extraction are studied. Microwave digestion is observed to qualitatively dissolve synthetic urban melt glass in less than 2 hours. Sodium hydroxide-based salt fusion is capable of recovery up to 75 % of the activity in synthetic urban melt glass in 2 hours. A sequential extraction procedure targeting water-soluble, exchangeable, reducible oxide, acid-soluble, and residual fractions is performed on irradiated uranium dioxide doped synthetic melt glass. The majority of the activity is released with the dissolution of the glass matrix in the residual fraction. Each method studied shows promise for the dissolution of urban melt glass, decreasing traditional melt glass digestion methods from over 3 days to as little as 2 hours.

Keywords

Iron; Nuclear Melt Glass Dissolution; Radiochemistry; Synthetic Nuclear Melt Glass; TRU Resin; Uranium

Disciplines

Agricultural Science | Animal Sciences | Chemistry | Radiochemistry

File Format

pdf

File Size

6.9 MB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

Download


Share

COinS