Most Popular Books by David Hobbs

The current design of the Salt Waste Processing Facility (SWPF) includes an auxiliary facility, the Actinide Finishing Facility, which provides a second contact of monosodium titanate (MST) to remove soluble actinides and strontium from waste if needed. This treatment will occur after cesium removal by Caustic-Side Solvent Extraction (CSSX). Although the process changes and safety basis implications have not yet been analyzed, provisions also exist to recover the MST from this operation and return to the initial actinide removal step in the SWPF for an additional (third) contact with fresh waste. A U.S. Department of Energy (DOE) request identified the need to study the following issues involving this application of MST: Determine the effect of organics from the solvent extraction (CSSX) process on radionuclide sorption by MST; Determine the efficiency of re-using MST for multiple contacts; and Examine fissile loading on MST under conditions using a waste containing significantly elevated concentrations of plutonium, uranium, neptunium, and strontium. This report describes the results of three experimental studies conducted to address these needs: (1) Addition of high concentrations of entrained CSSX solvent had no noticeable effect, over a two week period, on the sorption of the actinides and strontium by MST in a direct comparison experiment. (2) Test results show that MST still retains appreciable capacity after being used once. For instance, reused MST--in the presence of entrained solvent--continued to sorb actinides and strontium. (3) A single batch of MST was used to sequentially contact five volumes of a simulant solution containing elevated concentrations of the radionuclides of interest. After the five contacts, we measured the following solution actinide loadings on the MST: plutonium: 0.884 {+-} 0.00539 wt % or (1.02 {+-} 0.0112) E+04 {micro}g/g MST, uranium: 12.1 {+-} 0.786 wt % or (1.40 {+-} 0.104) E+05 {micro}g/g MST, and neptunium: 0.426 {+-} 0.00406 wt % or (4.92 {+-} 0.0923) E+03 {micro}g/g MST. (4) Over the duration of an experiment with the sequential strikes, the ability of MST to sorb actinides improved with additional strikes. This trend is counter-intuitive, but is confirmed by replicate experiments for plutonium, uranium, and neptunium. Conversely, over the duration of the experiment, the ability of MST to sorb strontium decreased the more it was used. This trend is confirmed by replicate experiment.

In this dissertation, I detail how capitalism has turned pollution into a generally accepted form of violence perpetuated in the name of economic health. Complete with a corps of risk managers and environmental consultants, neoliberal capitalism has fashioned pollution into a universal standard that functions as an ambient form of socialization. Pollution, I contend, serves as a social apparatus, an atmospheric example of what Jacques Rancire refers to as distributing the sensible (2004). Instead of being simply a by-product or unavoidable consequence, pollution serves as a constant reminder of the production/flow of capital and of modernitys dependency on heavy industries. But beyond its obvious emissions, spills, dumps, and tailing ponds, much of the fallout of pollution remains hidden. Thus, in mapping the social significance of pollution, the dissertation stresses these two conflicting principles: pollution is constantly present but also invisible. Pollution exists in the form of microscopic particles that travel on the wind and in waterways, penetrating ecosystems, neighbourhoods, homes, and bodies so that people are exposed to its poisons as a matter of fact, as a condition of the everyday, as an emblem of ones modernity. To counter this general acceptance of pollution, I engage in an ecological storytelling that utilizes comic book imagery, along with a mixture of archival and everyday material (government reports, tourist guides, newspaper clippings, postcards, and childrens drawings), to situate the specific harm done by the ambient toxins, chemicals emitted from specific polluting industries and imposed on specific people and ecologies. I concentrate on two ethnographic sites and two polluting industries, as half of the dissertation examines the politics of lead in Toronto (tracing its historical influence and public acceptance in two working class neighbourhoods), while the other half focuses on a massive petrochemical corridor that is located in and around the small city of Sarnia (in southwestern Ontario) and immediately adjacent to the First Nation of Aamjiwnaang. In addition to the more traditional ethnographic methods adopted in the textual chapters, the comics provide a stream of countermemories that refute neoliberal capitalism and its demand for more of the same.

Thermochemical processes are being developed to provide global-scale quantities of hydrogen. A variant on sulfur-based thermochemical cycles is the Hybrid Sulfur (HyS) Process which uses a sulfur dioxide depolarized electrolyzer (SDE) to produce the hydrogen. In FY05, testing at the Savannah River National Laboratory (SRNL) explored a low temperature fuel cell design concept for the SDE. The advantages of this design concept include high electrochemical efficiency and small volumetric footprint that is crucial for successful implementation on a commercial scale. A key component of the SDE is the ion conductive membrane through which protons produced at anode migrate to the cathode and react to produce hydrogen. An ideal membrane for the SDE should have both low ionic resistivity and low sulfur dioxide transport. These features allow the electrolyzer to perform at high currents with low potentials, along with preventing contamination of both the hydrogen output and poisoning of the catalysts involved. Another key component is the electrocatalyst material used for the anode and cathode. Good electrocatalysts should be chemically stable and low overpotential for the desired electrochemical reactions. This report summarizes results from activities to evaluate different membrane and electrocatalyst materials for the SDE. Several different types of commercially-available membranes were analyzed for ionic resistance and sulfur dioxide transport including perfluorinated sulfonic acid, sulfonated poly-etherketone-ketone, and poly-benzimidazole membranes. Of these membrane types, the poly-benzimidazole (PBI) membrane, Celtec-L, exhibited the best combination of characteristics for use in an SDE. Testing examined the activity and stability of platinum and palladium as electrocatalyst for the SDE in sulfuric acid solutions. Cyclic and linear sweep voltammetry revealed that platinum provided better catalytic activity with much lower potentials and higher currents than palladium. Testing also showed that the catalyst activity is strongly influenced by concentration of the sulfuric acid. Various cell configurations were examined with respect to the deposition of electrocatalyst and use of conductive carbon materials such as carbon cloth and carbon paper. Findings from these evaluations and the results of the membrane and electrocatalyst testing, we prepared three different membrane electrode assemblies (MEA) for electrolyzer testing. The first MEA consisted of a Nafion{reg_sign} membrane with platinum electrocatalyst deposited on carbon cloths, which were heat pressed onto the membrane, an assembly identical to those used in proton exchange membrane fuel cells. The second MEA also used a Nafion membrane with the electrocatalysts deposited directly onto the membrane. The third MEA proved similar to the second but utilized a PBI membrane in place of the Nafion{reg_sign} membrane. Tailor of the membrane and catalysts properties for the SDE system was concluded as a required step for the technology to move forward. It was also recommended the evaluation of the tested and new developed materials at conditions closer to the SDE operating conditions and for longer period of time.