Herein, a nuclear forensics investigation involving a uranium ore concentrate relies on accurate and precise analysis of impurities. Analytical data defensibility requires the use of reference ...materials as part of quality control. This study presents a compilation of trace element concentration results of the CUP-2 Uranium Ore Concentrate Standard measured by 11 different laboratories. The laboratories employed various dissolution methods, analytical preparation methods, and instrumental platforms. The data presented here contain concentrations of 66 impurities with up to 138 individual data points for each impurity. Consensus values have been assigned to each impurity following a statistical analysis of the data set.
A nuclear forensics investigation involving a uranium ore concentrate relies on accurate and precise analysis of impurities. Analytical data defensibility requires the use of reference materials as ...part of quality control. This study presents a compilation of trace element concentration results of the CUP-2 Uranium Ore Concentrate Standard measured by 11 different laboratories. The laboratories employed various dissolution methods, analytical preparation methods, and instrumental platforms. The data presented here contain concentrations of 66 impurities with up to 138 individual data points for each impurity. Consensus values have been assigned to each impurity following a statistical analysis of the data set.
This work investigated the application of diffusive gradients in thin films technique (DGT) to uranium speciation measurements in natural water. Two binding phases were examined, a commercially ...available affinity membrane, Whatman DE 81 (DE 81), with amino binding functional groups and the conventionally used Chelex 100 beads imbedded polyacrylamide hydrogel (Chelex) with iminodiacetate functional groups. The DGT devices assembled with the binding phases of DE 81 (DE 81 DGT) and Chelex gel (Chelex DGT) were tested both in synthetic river water solutions and in local river water. DE 81 DGT and Chelex DGT measured 80% and 75% of the total uranium in synthetic river water solution, respectively, and measured 73% and 60% of the total uranium in St. Lawrence River, Canada, respectively. The binding properties of the DE 81 membrane and Chelex gel for uranium, and the diffusion of uranyl complexes in the polyacrylamide gel (PAM) were also studied.
Nine laboratories participated in an intercomparison exercise organised by the European Radiation Dosimetry Group (EURADOS) for emergency radiobioassay involving four high-risk radionuclides ...((239)Pu, (241)Am, (90)Sr and (226)Ra). Diverse methods of analysis were used by the participating laboratories for the in vitro determination of each of the four radionuclides in urine samples. Almost all the methods used are sensitive enough to meet the requirements for emergency radiobioassay derived for this project in reference to the Clinical Decision Guide introduced by the NCRP. Results from most of the methods meet the requirements of ISO 28218 on accuracy in terms of relative bias and relative precision. However, some technical gaps have been identified. For example, some laboratories do not have the ability to assay samples containing (226)Ra, and sample turnaround time would be expected to be much shorter than that reported by many laboratories, as timely results for internal contamination and early decisions on medical intervention are highly desired. Participating laboratories are expected to learn from each other on the methods used to improve the interoperability among these laboratories.
A novel, rapid and completely automated method for the determination of long-lived actinides in air particulate samples was developed using ion chromatography separation prior to ICP-MS analyses. U, ...Pu and Am were pre-concentrated and separated from radioactive and stable interferences through a sequential arrangement of three columns (TEVA, U/TEVA, DGA) arranged in order to allow selective retention of the radioisotope on the designated resin. Detection and quantification of the various radioisotopes were performed on-line using inductively coupled plasma mass spectrometry (ICP-MS). Detection limits of 0.0006 ( super(238)U), 0.0063 ( super(239)Pu), 0.0041 ( super(240)Pu), 0.062 ( super(241)Am) mu Bq/m super(3) were obtained for air filters (based on 3000 m super(3) of air filtered). The automated procedure has been successfully tested on SRMs and spiked samples and showed high recovery yields (>90%). A total analysis time of 18 min is required for the separation, detection, and column rinsing/regeneration for subsequent analysis.
Exposure to indoor radon is of great concern because it is an environmental hazard for developing lung cancer. 210Pb, a radon decay product, was measured in home dust samples from the city of Ottawa, ...Canada. The 210Pb level in dust ranged from 33 to 352 Bq kg(-1), with the geometric mean and median values of 105 and 110 Bq kg(-1), respectively. Despite the complexity of the formation of 210Pb in the indoor environment, an encouraging correlation between 210Pb concentrations in home dust and radon levels in indoor air was observed when the measurement data were grouped according to four geographic regions of the city. This observation could lead to the development of 210Pb in home dust as a potential marker for indoor radon exposure.
This study helps fill in the literature relative to inland trade corridors and their effect on the space economy. Texas’ ‘Trade corridors’ provide an ideal framework for studying these relationships ...because of the state’s proximity to Mexico. Additionally, the passage of the North American Free Trade Agreement (NAFTA) provides a natural experiment to estimate how the increase in trade flows resulting from the enactment affected local economies along the trade corridors. The data set used to study these relationships is a spatial-temporal panel data set consisting of 254 counties over a 15 year time period The relationships are modeled using a fixed effects estimation with clustered robust standard errors. This study confirms NAFTA did have a positive effect on local trade-related employment especially along the dominant I35 corridor. Each 1 percent increase in the number of trucks traveling along I35 has created a .13 percent increase in trade-related employment along the corridor counties, ceteris paribus. Other variables affect trade-related employment. The model results indicate that for every 1 percent increase in manufacturing output in a Texas county, trade-related employment increases by 0.17 percent, but as the U.S. dollar increases in value, trade-related jobs are lost in Texas. A one point increase in the peso/US dollar exchange rate results in Texas trade-related employment declining by 1.7 percent as jobs move south. The model also enable us to estimate county-level gains and losses from future increases in trade volume and proposed changes in the state’s corridor structure. Federal Highway Administration forecasts through 2035 indicate trade-related jobs would increase by 32.1 percent on average in the counties along the I35 corridor. However, traffic diverted from I35 to the new Trans Texas Corridor (TTC) will negatively affect Denton, Tarrant, Johnson, Hays, and Comal counties as jobs shift, for example to Rockwall County.
Investigations into the complex interaction between combustion chemistry and the hydrodynamic flow field have been performed in both laminar and turbulent flames. Lifted turbulent spray flames were ...studied to gain insight into the role of oxidizer entrainment and mixing in the development of double flame structures in polydisperse ethanol sprays. OH Planar Laser-Induced Fluorescence (PLIF) has been used to demarcate reaction zone contours, while smoke visualization illuminates the dynamics between entrained oxidizer and the evaporating fuel spray. Results show that the double flame structure consists of an outer diffusion flame with an inner structure that transitions from mixing controlled to partially premixed combustion downstream of the leading edge. The flame stabilizes in the low-speed flow just outside the periphery of the spray cone, where flame propagation against the incoming flow is possible. The second phase of the research analyzed the response of laminar hydrocarbon-air flames to unsteady stretch via flame kernel-vortex interactions. A spark-ignited laminar premixed flame kernel, interacting with a single vortex toroid of variable strength, was investigated to quantify the transient coupling of flame chemistry and stretch. High-speed (4500 frames/second) broadband chemiluminescence imaging of natural CH*/OH* flame emission was utilized to map the available parameter space and probe both flame-flow and flame-flame interactions. Both methane and propane fuels were used with nitrogen diluent to carefully control flame speed. Emphasis was placed on propane-air flames since the heavier hydrocarbon fuel is considered more suited to fundamental studies related to internal combustion engine applications. Three vortex strengths, corresponding to different rotational or translational velocities, were chosen to interact with the growing flame surface. In the weakest flames, the strongest vortex has the ability to penetrate all the way through the flame kernel and essentially initiate a second propagating flame which is connected to the original flame surface. The ability to control the relative timing of ignition and vortex generation allows different interactions to be observed for a given set of experimental parameters. The effect of the vortex has been shown to greatly augment flame propagation in these laminar premixed flames with both local and global extinction possible under certain conditions.
