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Provided herein are methods and devices to enrich trace quantities of impurities in gaseous mixtures, such as hydrogen fuel. The methods and devices rely on concentration of impurities so as to allow the detection of the impurities using commonly-available detection methods.
In the transmutation process, minor actinides such as neptunium, americium and curium obtained from spent nuclear fuel are incorporated into new fuel that can be placed into a fast reactor, where these elements fission into products with shorter half-lives which reduces the health and safety hazards [1]. In order to better understand the all the involved processes, fundamental physical properties of actinides should be investigated, and for that reason, high-purity materials need to be produced. One of the main challenges in characterizing these materials is the lack of pure metal available for study, and lack of analytical methods to determine the purity. Trans-uranic elements are challenging to study because of the need to be handled in specialized facilities, safeguards concerns and they are not easily purchased and/or produced. High-purity Np metal is being produced at the Materials and Fuels Complex (MFC) of Idaho National Laboratory (INL), in a process of direct oxide reduction developed by Squires and Lessing [2], with a target purity of 99.999%. The goal of this research is to develop methods to determine the impurities in the Np metal, with detection limits low enough to achieve this purity level. In this work, we have used several ICP-MS and ICP OES techniques, but the focus was the method development using a recently acquired Double-Focusing Sector Field Inductively Coupled Plasma Mass Spectrometer (SF-ICP-MS). To produce the Np metal, approximately 20 g of the neptunium oxide powder was calcined at 800 oC for 6 h in a magnesium oxide crucible, which is placed inside a stainless steel crucible, that goes into the Hot Uniaxial Press (HUP) furnace insert. After the calcining step, the Np oxide was mixed with approximately 9 g of calcium metal and 100 g of ultra-dry calcium chloride. The HUP furnace was heated in a ramp rate of 50 oC min -1 up to 1000 oC. When the reaction mixture reached 850 oC, a tantalum stirrer was activated at 100 rpm. After the tantalum stirrer was removed and the mixture cooled overnight, the MgO crucible was opened with a hammer and chisel to retrieve the Np metal button at the bottom of the reaction mixture [2]. Prior to the dissolution process, the surface contaminants of the sample were removed. The Np button was washed in 10 mL of ultra-pure water for 1 min, with a faint reaction observed on the surface, indicating the presence of Ca metal. The water-washed sample was placed in a tube with 2 M HCl for only 3 s, as a vigorous reaction in the button surface was observed. The leachates were saved for further analysis. The sample was then rinsed with ultra-pure water and air-dried prior to dissolution. The cleaned sample was placed in a PTFE beaker and 25 mL of 6 M HCl and 150 µL of 24 M HF were added. After 10 minutes of reaction, the beaker was placed on a hot plate for 1 h and 30 min, followed by the addition of 1 mL of 16 M HNO3 and allowed to react for a further 1 h and 20 min. The sample was removed from heat and 10 mL of HNO3 16 M was added to react with the HCl. The beaker was covered and left for overnight reaction, producing a solution with approximately 20 mL of final volume. A Quadrupole Inductively Coupled Plasma Mass Spectrometer (Q-ICP-MS, Perkin Elmer ELAN DRC II Q-ICP-MS) was used to obtain qualitative mass spectra for the dissolution blank, each of the leachates and the dissolved sample. In the water leachate spectrum mainly Ca and Mg were observed, while the acid wash had a similar peak pattern to the one observed for the Np metal sample, indicating that the process not only removed surface contamination, but also reacted with the sample itself. In the Np material spectrum, Ta and actinides were identified as candidates for major contaminants, as the most intense peaks corresponded to the mass-to-charge ratios of these elements. Minor contaminants included Al, Au, Ca, Cr, Fe, I, Na, Nb, Pb, Sn, Ti, Tl, V, Y. The presence of impurities in the material could have originated from several sources, such as the materials used for the casting process, the use of impure NpO2 or contamination of reagents and materials used for the analysis. Some of the isotopes listed as potential contaminants are susceptible to spectral interferences, so Double-Focusing SF-ICP-MS (Nu Instruments Attom ES HR-ICP-MS) was used for the quantitative analysis. For each isotope determined, several items were evaluated: raw signal of a blank solution, sensitivity and determination coefficient of calibration curves, possibility of interferences and comparison of results obtained for at least two resolving powers (RP): 300 and 4000. The evaluation of the signal in a blank solution can indicate if a spectral interference from the plasma gas and/or the solvent was successfully resolved (commonly observed for 52Cr+/40Ar12C+, for example). It is important to highlight that a signal reduction is expected when a higher RP is used, as the ion beam transmission is decreased by the use of na
In the transmutation process, minor actinides such as neptunium, americium and curium obtained from spent nuclear fuel are incorporated into new fuel that can be placed into a fast reactor, where these elements fission into products with shorter half-lives which reduces the health and safety hazards. In order to better understand the all the involved processes, fundamental physical properties of actinides should be investigated, and for that reason, high-purity materials need to be produced. One of the main challenges in characterizing these materials is the lack of pure metal available for study, and lack of analytical methods to determine the purity. Trans-uranic elements are challenging to study because of the need to be handled in specialized facilities, safeguards concerns and they are not easily purchased and/or produced. High-purity Np metal is being produced at the Materials and Fuels Complex (MFC) of Idaho National Laboratory (INL), in a process of direct oxide reduction developed by Squires and Lessing, with a target purity of 99.999%. The goal of this research is to develop methods to determine the impurities in the Np metal, with detection limits low enough to achieve this purity level. In this work, we have used several ICP-MS and ICP OES techniques, but the focus was the method development using a recently acquired Double-Focusing Sector Field Inductively Coupled Plasma Mass Spectrometer (SF-ICP-MS). To produce the Np metal, approximately 20 g of the neptunium oxide powder was calcined at 800 oC for 6 h in a magnesium oxide crucible, which is placed inside a stainless steel crucible, that goes into the Hot Uniaxial Press (HUP) furnace insert. After the calcining step, the Np oxide was mixed with approximately 9 g of calcium metal and 100 g of ultra-dry calcium chloride. The HUP furnace was heated in a ramp rate of 50 oC min -1 up to 1000 oC. When the reaction mixture reached 850 oC, a tantalum stirrer was activated at 100 rpm. After the tantalum stirrer was removed and the mixture cooled overnight, the MgO crucible was opened with a hammer and chisel to retrieve the Np metal button at the bottom of the reaction mixture. Prior to the dissolution process, the surface contaminants of the sample were removed. The Np button was washed in 10 mL of ultra-pure water for 1 min, with a faint reaction observed on the surface, indicating the presence of Ca metal. The water-washed sample was placed in a tube with 2 M HCl for only 3 s, as a vigorous reaction in the button surface was observed. The leachates were saved for further analysis. The sample was then rinsed with ultra-pure water and air-dried prior to dissolution. The cleaned sample was placed in a PTFE beaker and 25 mL of 6 M HCl and 150 µL of 24 M HF were added. After 10 minutes of reaction, the beaker was placed on a hot plate for 1 h and 30 min, followed by the addition of 1 mL of 16 M HNO3 and allowed to react for a further 1 h and 20 min. The sample was removed from heat and 10 mL of HNO3 16 M was added to react with the HCl. The beaker was covered and left for overnight reaction, producing a solution with approximately 20 mL of final volume. A Quadrupole Inductively Coupled Plasma Mass Spectrometer (Q-ICP-MS, Perkin Elmer ELAN DRC II Q-ICP-MS) was used to obtain qualitative mass spectra for the dissolution blank, each of the leachates and the dissolved sample. In the water leachate spectrum mainly Ca and Mg were observed, while the acid wash had a similar peak pattern to the one observed for the Np metal sample, indicating that the process not only removed surface contamination, but also reacted with the sample itself. In the Np material spectrum, Ta and actinides were identified as candidates for major contaminants, as the most intense peaks corresponded to the mass-to-charge ratios of these elements. Minor contaminants included Al, Au, Ca, Cr, Fe, I, Na, Nb, Pb, Sn, Ti, Tl, V, Y. The presence of impurities in the material could have originated from several sources, such as the materials used for the casting process, the use of impure NpO2 or contamination of reagents and materials used for the analysis. Some of the isotopes listed as potential contaminants are susceptible to spectral interferences, so Double-Focusing SF-ICP-MS (Nu Instruments Attom ES HR-ICP-MS) was used for the quantitative analysis. For each isotope determined, several items were evaluated: raw signal of a blank solution, sensitivity and determination coefficient of calibration curves, possibility of interferences and comparison of results obtained for at least two resolving powers (RP): 300 and 4000. The evaluation of the signal in a blank solution can indicate if a spectral interference from the plasma gas and/or the solvent was successfully resolved (commonly observed for 52Cr+/40Ar12C+, for example). It is important to highlight that a signal reduction is expected when a higher RP is used, as the ion beam transmission is decreased by the use of narrower slits
The work presented here is a study of the impurity MgOHCl in molten chloride salts, toward the eventual goal of electrochemically removing it from operational molten-chloride-based concentrating solar power (CSP) plants.1,2 Implementation of molten chloride salts as a heat transfer fluid is among the most promising pathways for decreasing the levelized cost of energy (LCOE) of CSP systems because its high thermal stability allows higher operating temperatures, and thus, greater efficiency. However, this impurity - formed when MgCl2 salts are exposed to air and moisture - cause significant corrosion of containment alloys.1 Therefore, we have developed and validated in a laboratory setting: 1) a method for the formation of MgOHCl for controlled impurity spike in molten salt for its further sensing, evaluation, and reduction; 2) evaluated its diffusion in the molten salt, and 3) began assessing its electrochemical properties. Our findings allow us to propose solutions for efficiently and instantly removing MgOHCl from an operational CSP plant.
High gradient and high quality factor superconducting radiofrequency (SRF) cavities are essential for efficient particle acceleration in next-generation accelerators. This work demonstrates that the superconducting performance of bulk niobium can be enhanced through a controlled introduction of interstitial oxygen and nitrogen. Thermal and chemical surface treatments modify the concentration and distribution of these impurities, enabling systematic tuning of SRF cavity performance. By combining cavity RF measurements with quantitative materials characterizations, we isolate the impact of impurity concentration on BCS surface resistance and identify the mechanisms by which interstitial impurities alter the superconducting properties of niobium. We find that nitrogen is an order of magnitude more effective than oxygen in reducing BCS resistance at 16 MV/m and that the reduction arises from a combination of mean free path optimization and superconducting gap enhancement. Using these insights, we develop a predictive model that estimates cavity performance directly from room temperature sample material studies, reducing the reliance on full-scale cryogenic tests for surface treatment development. We then apply this model to explore co-doping strategies, demonstrating that combining interstitial oxygen and nitrogen achieves a synergistic reduction in BCS resistance. These results establish co-doping as a viable path for the development of surface-engineered niobium for future high quality factor SRF applications.
Understanding the interfacial evolution of alloys in molten salt with different amounts of water (H 2 O) and oxygen (O 2 ) impurities is significant for applications in many fields, including concentrated solar power, molten salt reactors, and applications in pyrochemical reprocessing and electrorefining. Additionally, the impurity-driven corrosion mechanisms that lead to various morphological and chemical evolution characteristics at the interfaces of structural alloys and molten salts are not fully understood. In the present work, the three-dimensional (3D) morphological evolution of Ni-20Cr microwires in LiCl-KCl was studied at 500 °C under different moisture and oxygen conditions using in situ synchrotron transmission X-ray microscopy (TXM) and scanning transmission electron microscopy (STEM) techniques. No significant morphological changes were observed in Ni-20Cr microwires under vacuum conditions. However, the wires exhibited distinct morphological evolutions when exposed to molten salt containing H 2 O alone, as well as when both H 2 O and O 2 were present. Furthermore, Cr 2 O 3 precipitates were observed in the molten salt during corrosion with only H 2 O present, while Cr 6+ species were identified in the salt when O 2 was added. Further, these findings are crucial for understanding the corrosion mechanisms of molten salt with different amounts of H 2 O and O 2 contamination, providing insights for developing corrosion mitigation methods and improving the stability of containment alloys in molten salt applications.
Hole localization is a root cause of difficulties in p-type doping of aluminum nitride. Herein, the stability of localized holes in AlN and their susceptibility to self-trapping within bulk material or in the presence of isovalent elements and acceptor impurities are calculated. It is found that self-trapped holes are metastable in bulk AlN, and also exhibit a very low barrier to detrapping. However, holes become trapped in the presence of acceptor impurities as well as isovalent elements such as B, In, and Sc, and may contribute to the broad luminescence observed in AlN alloys. It is also found that hole trapping contributes to the large ionization energies for acceptors in AlN. Most acceptors can also trap a second hole, becoming positively charged and further exacerbating difficulties in doping aluminum nitride p type. Furthermore, the stability of trapped holes is found to scale with atomic size mismatch to Al.
Divertor plasma-facing components (PFCs) in a tokamak are typically designed to withstand average steady-state heat loads of about 5–10 MW/m 2 , a limit that applies to both solid and liquid lithium (LL) PFCs. Exceeding these design values can result in surface damage to tungsten PFCs or excessive lithium (Li) evaporation in liquid lithium divertor (LLD) PFCs. Since exceeding the divertor heat load limits has serious consequences, it is therefore prudent to develop a tool to reduce the divertor heat load and bring the heat load to within the design limit without affecting the plasma performance. Active low Z impurity injection such as Li has been suggested as a potential solution to mitigate excess heat flux as suggested previously, given that non-coronal radiation can be quite large ~ 20–30 MJ per mole of injected Li. Li is considered desirable for reducing the edge neutral recycling helping to improve plasma energy confinement. In this paper, we model the Impurity Power Dropper (IPD) to investigate its potential of divertor heat flux control. The IPD is typically located at the top of the tokamak device and uses a vertical drift tube of a few meters. In the 2 m drift tube case, the IPD powder is accelerated to ~ 6 m/sec before reaching the plasma with the upper divertor configuration, matching the condition for the in-board side pellet injection case. By modeling the IPD geometry we determined the IPD powder deposition profile, and thus the non-coronal radiation and ionization profiles in time as well. From the enhanced radiation power loss, it is therefore possible to reduce the divertor heat load using the divertor simulation code. In conclusion, the IPD divertor heat flux control can be tested in the facilities with IPD including ST-40, DIII-D, EAST, WEST and NSTX-U.
The present study tries to investigate Wiedemann-Franz law near and far from the critical temperatures, given the tunneling between the grains in Cooper pair fluctuation propagator and impurity vertex. By means of Dyson’s equation, the Cooper pair fluctuation propagator, L(qkΩ{sub μ}) and the Cooperon (impurity vertex), λ(q, k, ε{sub 1}, ε{sub 2}), are initially calculated in the presence of tunneling between the grains. Then, the three distinct contributions of density of states, Maki-Thompson, and Aslamazov-Larkin, are calculated in the frameworks of the Green’s functions formalism and the Kubo formula technique. The evaluation is conducted under the limited tunneling conductance between the grains. Findings show that although the tunneling is efficient near the critical temperature, it is not effective when it is far from the critical temperature Compared to that in high temperatures, moreover, the deviation from the Wiedemann-Franz law is much more evident in low temperatures.
The effect of tellurium impurities on the electrical conductivity (σ), Seebeck coefficient (α), and Hall coefficient R of extruded Bi{sub 85}Sb{sub 15} + 0.001 аt.% Pb is studied in the temperature range 77–300 K. It is found that doping with tellurium impurities up to 0.001 at. % compensating acceptor Pb atoms leads to a strong decrease in the electron density and, consequently, to an increase in σ and significant decrease in the values of α and R. The materials obtained can be used as the n-branch of thermoelements operating at temperatures of ~77 K.
As there are direct and indirect impacts of feed material purity on the aluminum production process and metal grade, there is a high demand on the so-called pure smelter grade alumina (SGA)—the main feedstock for aluminum production. In this work, impurities within the precursor gibbsite used for SGA production and SGA are studied using NanoSIMS and XPS with a focus on sodium—the most abundant impurity. Although the industry trend is towards minimizing sodium due to the well-known negative impacts on the process, high sodium is also correlated with relatively attrition-resistant calcined products. Here, we show that this relationship is indirect and arises from sodium’s role in inhibiting α-alumina formation. Alpha alumina formation in SGA has previously been demonstrated to induce a macro-porous and therefore attrition-prone microstructure. Sodium distribution within the precursor gibbsite and its migration during the calcination process are proposed to be most likely responsible for the spatial distribution of α-alumina within the calcined product grain. This in turn determines the behavior of the product during its transportation and handling (i.e., attrition). Therefore, tolerance of a certain amount of sodium within the precursor material does demonstrate a net benefit while balancing its negative impacts on the process.
The corrosion of materials in molten fluoride salts is largely influenced by the presence of impurities in the salt. Very few studies have been done on the effect of oxide impurities on the corrosion of structural alloys in molten fluoride salts. In this study, corrosion behavior of selected alloys was studied in molten FLiNaK with the addition of different oxides such as Li 2 O, NiO, and Cr 2 O 3 . The results show that addition of oxides can lead to significant effects on this corrosion, depending on the type and amount of oxide added and the alloy being used.
Graphite has been used in large volumes as a structural material and neutron moderator since the earliest days of nuclear fission. However, no international consensus exists on the disposal of irradiated graphite, leaving much of the historic radioactive graphite inventory in interim vault or silo storage. With several new graphite-moderated reactors planned or under construction, the issue of graphite waste management is becoming increasingly urgent. This paper reviews and quantifies impurities in both historic and modern nuclear graphite, with emphasis on nitrogen—responsible for much of the 14 C inventory—and chlorine, which plays a critical role in repository performance and design. Modern graphites, benefitting from stringent quality-control measures developed for non-nuclear industries, meet or exceed the ASTM Ultra-High Purity nuclear standards, even without halide purification. Both chlorine and nitrogen concentrations have declined over time. For chlorine, identified as a key impurity influencing U.S. waste repository design, we propose a target of 0.1 appm in as-fabricated billets as a reasonable benchmark. Nitrogen sources are traced throughout the graphite production process, with surface and bulk concentrations characterized for all materials studied. Modern graphites commonly exhibit nitrogen levels below 5 appm, with values approaching 1 appm achievable. Using such reduced-nitrogen grades is critical to keeping graphite-induced radioactivity below the greater-than-Class-C waste threshold, thereby avoiding disposal cost penalties of nearly an order of magnitude.
Metal corrosion from exposure to supercritical fluids is a long-standing challenge lacking atomistic understanding for effective corrosion prevention in diverse important applications. Here, in this work, reactions relevant to corrosion in supercritical CO 2 (sCO 2 ), with H 2 O and NO 2 as impurities, are revealed using ab initio molecular dynamics and enhanced sampling methods. While little reactivity is observed in bulk sCO 2 , the iron surface is found to play a crucial almost-catalytic role in its own corrosion, activating the inert CO2 and hence facilitating $\ast$HCO 3 – and $\ast$CO 3 2– formation at the interface. Moreover, the hydrogen bond network of $\ast$H 2 O assists the H shuttling to the activated CO 2 and impurities, forming reactive species observed in experiments. Such atomistic insight elucidates the reaction mechanisms of metal corrosion in aqueous and supercritical fluids and can point to possible remedies.
Ultrasonic sensing is a non-invasive technique for monitoring impurity gas composition in various industrial applications where safety and regulatory compliance are crucial. In this study, ultrasonic sensing and neural networks were used to analyze impurity gases (i.e., air and argon) in helium. An experimental platform was established to acquire ultrasonic data. In the forward problem, an artificial neural network (ANN) model was used to forecast the response and time-of-flight (TOF) based on the excitation, and argon and air concentrations. The inverse problem was solved using a convolutional neural network (CNN) to predict the argon and air concentrations given the ultrasonic response and excitation. The results showed that the ANN accurately predicted the ultrasonic response and the change in TOF with concentration. As the air concentration was increased from 0 to 9.8%, the TOF sensitivity to detect argon decreased by 39.8% and 16.1% from ANN and sound speed theory, respectively. The CNN demonstrated high accuracy in predicting concentrations for inputs in the testing dataset. The application of the trained CNN indicated that it over-predicts air concentration while under-predicting the argon concentration. To improve accuracy, the predicted air and argon concentrations should be corrected by -0.992% and 1.027% bias, respectively.
Modifications of the drift-kinetic transport code XGC0 to include the transport, ionization, and recombination of individual charge states, as well as the associated radiation, are described. The code is first applied to a simulation of an NSTX H-mode discharge with carbon impurity to demonstrate the approach to coronal equilibrium. The effects of neoclassical phenomena on the radiated power profile are examined sequentially through the activation of individual physics modules in the code. Orbit squeezing and the neoclassical inward pinch result in increased radiation for temperatures above a few hundred eV and changes to the ratios of charge state emissions at a given electron temperature. As a result, analogous simulations with a neon impurity yield qualitatively similar results.
Uhlirova et al. reported superconductivity in LuBe 13 and assigned it tentatively to be BCS-type, with specific heat measurements down to 0.45 K showing the partial onset of a bulk transition. In order to check LuBe13 for unconventional behavior, as well as to further characterize the unconventional superconductivity in UBe 13 , we have prepared and characterized down to 0.40 K three arc-melted samples each of MBe 13 , M = Lu, U, using three different purities (99.999%, 99.96%, and 99.8%) of Be but with the same high purity M (Lu or U) for all three. The measurements down to 0.40 K allow the detection of the maximum in the specific heat in all three LuBe 13 samples. The resulting superconducting properties strongly depend on impurity level in UBe 13 (40% decrease in ΔC/T c , 15% decrease in T c mid ) while the three LuBe 13 samples exhibit significantly smaller changes (10% and 5% respectively) with purity. The comparison of properties at the first two levels of purity (99.999% vs 99.96%) is even more disparate: 12% decrease in T c mid in UBe 13 vs no change in LuBe 13 . Furthermore, these results are consistent with previous results that argue for unconventional superconductivity in UBe 13 and are consistent with Uhlirova et al.‘s assignment of LuBe 13 as a conventional, BCS superconductor. More generally, this example of comparing superconducting properties vs-controlled gradations in impurity levels with two compositionally and structurally “matched” superconducting compounds (one conventional and one of to-be-determined coupling behavior) offers a new method for determining unconventional behavior.
Cefoperazone (CFP) is a potent antibacterial agent that is widely used for the treatment of bacterial infections. Previously, we found that both the C-7 and C-3 substituents of CFP are toxic functional groups, and two groups could affect gene expression in zebrafish embryos, thereby resulting in variable abnormal phenotypes. (6R, 7S)-cefoperazone (7S-CFP) is the 7-epimer of CFP and 1-methyl-1H-tetrazole-5-thiol (MTT) is the C-3 substituent of CFP. Both molecules are impurities isolated from CFP that can induce adverse effects. Transcriptome analysis was performed in the present study to identify differentially expressed genes (DEGs), coupled with Raman mapping of individual organ regions to detect changes in the biochemical composition of zebrafish embryos, which reflect the differences in distribution of the compounds. CFP, 7S–CFP, and MTT exposure altered the expression of 254, 368, and 1153 genes, respectively. Gene ontology analysis revealed that various processes related to development, growth, and morphology of tissues were significantly enriched with DEGs. We integrated seven co-DEGs with protein-protein interaction networks and identified various developmental processes that were regulated by the three compounds, including vasodilation, eye, brain, melanogenesis, and heart looping. Our findings suggested that Calca and Ptger4a may be potentially utilized as novel biomarkers for CFP, which causes bleeding. Raman analysis indicated that CFP, 7S-CFP, and MTT exhibited abnormal maps in tissues, which coincided with changes in their expression and morphological features. This study may provide bioinformatics and spectral information that may be used in further investigations on the relationship between structure and toxicity of drugs and impurities. - Highlights: • We studied the relationship between the structure and toxicity of cefoperazone. • Transcriptome strategy was performed to identify differentially expressed genes. • We integrated seven co-DEGs with protein-protein interaction networks. • Our results founded the novel biomarkers for cefoperazone, which causes bleeding. • Raman analysis indicated that three compounds exhibited abnormal maps in tissues.