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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Irreversible Wash Aid Additive for Cesium Mitigation: WARRP Demonstration

This activity demonstrated, on a practical scale, the primary unit operations for building a containment structure for radioactive wash waters, washing down a hypothetically radioactively contaminated vehicle, collecting the hypothetically radioactive slurry waste water, filtering the hypothetically radioactive wash waters, disassembling the containment, and transporting the materials for final disposition.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

Irreversible Wash Aid Additive for Cesium Mitigation. Small-Scale Demonstration and Lessons Learned

The Irreversible Wash Aid Additive process has been under development by the U.S. Environmental Protection Agency (EPA) and Argonne National Laboratory (Argonne). This process for radioactive cesium mitigation consists of a solution to wash down contaminated structures, roadways, and vehicles and a sequestering agent to bind the radionuclides from the wash water and render them environmentally immobile. The purpose of this process is to restore functionality to basic services and immediately reduce the consequences of a radiologically-contaminated urban environment. Research and development have resulted in a down-selection of technologies for integration and demonstration at the pilot-scale level as part of the Wide Area Recovery and Resiliency Program (WARRP) under the Department of Homeland Security and the Denver Urban Area Security Initiative. As part of developing the methods for performing a pilot-scale demonstration at the WARRP conference in Denver in 2012, Argonne conducted small-scale field experiments at Separmatic Systems. The main purpose of these experiments was to refine the wash water collection and separations systems and demonstrate key unit operations to help in planning for the large scale demonstration in Denver. Since the purpose of these tests was to demonstrate the operations of the system, we used no radioactive materials. After a brief set of experiments with the LAKOS unit to familiarize ourselves with its operation, two experiments were completed on two separate dates with the Separmatic systems.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

Irreversible Wash Aid Additive for Cesium Mitigation: Phase II. Selection and/or Modification of COTS Field Portable Waste Water Systems

After an accidental or malicious release of radioactivity, large urban areas may be contaminated, compromising response efforts by first responders and law enforcement officials. In addition, some public services (e.g., drinking water and wastewater treatment, electrical power distribution, etc.) may be disrupted. In such an event, it may be important to deploy mitigation efforts in certain areas to restore response activities and public services (Fig. S-1). This report explores the state-of-the-art approach for a system to rapidly return critical infrastructure components to service following a cesium-137 (Cs-137) radiological dispersal device (RDD) release while avoiding the spread of Cs-137 beyond its original deposition area and minimizing the amount of Cs-137-contaminated wastewater. Specifically, we describe a wash system consisting of chemical additives added to fire hydrant water and irreversible solid sequestering agents added as the water is collected and treated for recycle in situ. The wash system is intended to be a rapidly deployable, cost-effective means of mitigating an urban setting for the purpose of restoring critical infrastructure and operational activities after a radiological release.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2016

Efficient cesiation in RF driven surface plasma negative ion source

Experiments on hydrogen negative ions production in the large radio-frequency negative ion source with cesium seed are described. The system of directed cesium deposition to the plasma grid periphery was used. The small cesium seed (∼0.5 G) provides an enhanced H{sup −} production during a 2 month long experimental cycle. The gradual increase of negative ion yield during the long-term source runs was observed after cesium addition to the source. The degraded H{sup −} production was recorded after air filling to the source or after the cesium washing away from the driver and plasma chamber walls. The following source conditioning by beam shots produces the gradual recovery of H{sup −} yield to the high value. The effect of H{sup −} yield recovery after cesium coverage passivation by air fill was studied. The concept of cesium coverage replenishment and of H{sup −} yield recovery due to sputtering of cesium from the deteriorated layers is discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

The promotional effects of cesium promoter on higher alcohol synthesis from syngas over cesium-promoted Cu/ZnO/Al2O3 catalysts

In this study, the promotional effects of cesium promoter on higher alcohol (C2+OH) synthesis from syngas over Cs-Cu/ZnO/Al2O3 catalysts were investigated using a combined experimental and theoretical density functional theory (DFT) calculation method. In the presence of cesium, the C2+OH productivity increases from 77.1 g•kgcat-1•h-1 to 157.3 g•kgcat-1•h-1 at 583 K due to the enhancement of the initial C–C bond formation. Detailed analysis of chain growth probabilities (CGPs) confirms that initial C–C bond formation is the rate-determining step in the temperature range of 543-583 K. Addition of cesium promoter significantly increases the productivities of 2-methyl-1-propanol, while the CGPs values (C3* to 2-methyl-C3*) is almost unaffected. With the assistance of cesium promoter, the CGPs of the initial C–C bond formation step (C1* to C2*) could be increased from 0.13 to 0.25 at 583 K. DFT calculations indicate that the initial C–C bond formation is mainly contributed by the HCO+HCO coupling reaction over the ZnCu(211) model surface. In the presence of the Cs2O, the stabilities of key reaction intermediates such as HCO and H2CO are enhanced which facilitates both HCO+HCO and HCO+H2CO coupling reaction steps with lower activation barriers over the Cs2O-ZnCu(211) surface. The promotional effects of cesium on the C2+OH productivity are also benefited from the competitive CH+HCO coupling reaction over CH hydrogenation that leads to lower alkane formation. In addition, Bader charge analysis suggests that the presence of cesium ions would facilitate the nucleophilic reaction between HCO and H2CO for initial C–C bond formation. This work was supported by the National Natural Science Foundation of China (No. 91545114 and No. 91545203). We appreciate the joint PhD scholarship support from the China Scholarship Council. The authors would also like to thank the support from Collaborative Innovation Center of Chemistry for Energy Materials (2011-iChEM). DM was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Computing time was granted by the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility located at Pacific Northwest National Laboratory (PNNL) and sponsored by DOE’s Office of Biological and Environmental Research. PNNL is a multiprogram national laboratory operated for DOE by Battelle Memorial Institute. We also appreciate the support from Sinochem Quanzhou Petrochemical Co. Ltd.

cesium↗
DOE OSTI2015

Maintenance and operation procedure, and feedback controls of the J-PARC RF-driven H{sup −} ion source

In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) second stage requirements of an H{sup −} ion beam of 60mA within normalized emittances of 1.5πmm•mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of longer than 1month, the J-PARC cesiated RF-driven H{sup −} ion source was developed by using an internal-antenna developed at the Spallation Neutron Source (SNS). The maintenance and operation procedure to minimize the plasma chamber (PCH) replacement time on the beam line, which is very important to maximize the J-PARC beam time especially for an antenna failure, is presented in this paper. The PCH preserved by filling argon (Ar) gas inside after pre-conditioning including pre-cesiation to produce the required beam at a test-stand successfully produced the required beam on the beam line with slight addition of cesium (Cs). The methods of the feedback controls of a 2MHz-RF-matching, an H{sup −} ion beam intensity and the addition of Cs are also presented. The RF-matching feedback by using two vacuum variable capacitors (VVCs) and RF-frequency shift produced the almost perfect matching with negligibly small reflected RF-power. The H{sup −} ion beam intensity was controlled within errors of ±0.1mA by the RF-power feedback. The amount of Cs was also controlled by remotely opening a Cs-valve to keep the RF-power lower than a settled value.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Negative hydrogen ion production mechanisms

Negative hydrogen/deuterium ions can be formed by processes occurring in the plasma volume and on surfaces facing the plasma. The principal mechanisms leading to the formation of these negative ions are dissociative electron attachment to ro-vibrationally excited hydrogen/deuterium molecules when the reaction takes place in the plasma volume, and the direct electron transfer from the low work function metal surface to the hydrogen/deuterium atoms when formation occurs on the surface. The existing theoretical models and reported experimental results on these two mechanisms are summarized. Performance of the negative hydrogen/deuterium ion sources that emerged from studies of these mechanisms is reviewed. Contemporary negative ion sources do not have negative ion production electrodes of original surface type sources but are operated with caesium with their structures nearly identical to volume production type sources. Reasons for enhanced negative ion current due to caesium addition to these sources are discussed.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

Enhancement of persistent luminescence of ZnTa{sub 2}O{sub 6}:Pr{sup 3+} by addition Li{sup +}, Na{sup +}, K{sup +} and Cs{sup +} ions

Graphical abstract: The incorporation of the alkali metals (Li, Na, K and Cs) as co-dopants in ZnTa{sub 2}O{sub 6}:Pr{sup 3+} phosphor improved the lifetime of the persistent emission by increasing the quantity of the electron trapping centres. - Highlights: • ZnTa{sub 2}O{sub 6}:Pr{sup 3+} was co-doped with Li{sup +}, Na{sup +}, K{sup +} or Cs{sup +} ions. • Phase pure samples were synthesised. • Enhancement of the persistent emission was achieved by co-doping. • Corresponding electron trapping centres were quantified by a TL reader. - Abstract: Enhancement of the persistent emission was achieved by co-doping ZnTa{sub 2}O{sub 6}:Pr{sup 3+} with Li{sup +}, Na{sup +}, K{sup +} or Cs{sup +} ions. Phase pure samples were synthesised and it was confirmed by the X-ray diffraction pattern which matches that of the standard data. Incorporation of the co-dopant ions introduced strain into the phosphor, which increased with an increase in the ionic radius of the co-dopant ion. The scanning electron microscope image shows that the particles were agglomerated, and the surface images obtained using the Time of flight secondary ion mass spectroscopy showed that the dopant and the co-dopant ions in the phosphor were homogeneously distributed. The persistent emission was enhanced by the co-dopant ions as shown by the lifetime values calculated from the phosphorescence decay curves, and the corresponding electron trapping centres were quantified by thermoluminescence reader.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

CsI-Antisolvent Adduct Formation in All-Inorganic Metal Halide Perovskites

The excellent optoelectronic properties shown by hybrid organic/inorganic metal halide perovskites are all predicated on precisely controlling the exact nucleation and crystallization dynamics that occur during film formation. In general, high-performance thin films are obtained by a method commonly called solvent engineering (or antisolvent quench) processing. The solvent engineering method removes excess solvent, but importantly leaves behind solvent that forms chemical adducts with the lead-halide precursor salts. These adduct-based precursor phases control nucleation and the growth of the polycrystalline domains. There has not yet been a comprehensive study comparing the various antisolvents used in different perovskite compositions containing cesium. In addition, there have been no reports of solvent engineering for high efficiency in all-inorganic perovskites such as CsPbI 3 . In this work, inorganic perovskite composition CsPbI 3 is specifically targeted and unique adducts formed between CsI and precursor solvents and antisolvents are found that have not been observed for other A-site cation salts. These CsI adducts control nucleation more so than the PbI 2 -dimethyl sulfoxide (DMSO) adduct and demonstrate how the A-site plays a significant role in crystallization. The use of methyl acetate (MeOAc) in this solvent engineering approach dictates crystallization through the formation of a CsI-MeOAc adduct and results in solar cells with a power conversion efficiency of 14.4%.

14 SOLAR ENERGY↗
DOE OSTI2017

High-performance formamidinium-based perovskite solar cells via microstructure-mediated δ-to-α phase transformation

The δ → α phase transformation is a crucial step in the solution-growth process of formamidinium-based lead triiodide (FAPbI 3 ) hybrid organic–inorganic perovskite (HOIP) thin films for perovskite solar cells (PSCs). Because the addition of cesium (Cs) stabilizes the α phase of FAPbI 3 -based HOIPs, here our research focuses on FAPbI 3 (Cs) thin films. We show that having a large grain size in the δ-FAPbI 3 (Cs) non-perovskite intermediate films is essential for the growth of high-quality α-FAPbI 3 (Cs) HOIP thin films. Here grain coarsening and phase transformation occur simultaneously during the thermal annealing step. A large starting grain size in the δ-FAPbI 3 (Cs) thin films suppresses grain coarsening, precluding the formation of voids at the final α-FAPbI 3 (Cs)–substrate interfaces. PSCs based on the interface void-free α-FAPbI 3 (Cs) HOIP thin films are much more efficient and stable in the ambient atmosphere. This interesting finding inspired us to develop a simple room-temperature aging method for preparing coarse-grained δ-FAPbI 3 (Cs) intermediate films, which are subsequently converted to coarse-grained, high-quality α-FAPbI 3 (Cs) HOIP thin films. As a result, this study highlights the importance of microstructure meditation in the processing of formamidinium-based PSCs.

14 SOLAR ENERGY↗
DOE OSTI2019

Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites

The role of the alkali metal cations in halide perovskite solar cells is not well understood. Using synchrotron-based nano–x-ray fluorescence and complementary measurements, we found that the halide distribution becomes homogenized upon addition of cesium iodide, either alone or with rubidium iodide, for substoichiometric, stoichiometric, and overstoichiometric preparations, where the lead halide is varied with respect to organic halide precursors. Halide homogenization coincides with long-lived charge carrier decays, spatially homogeneous carrier dynamics (as visualized by ultrafast microscopy), and improved photovoltaic device performance. We found that rubidium and potassium phase-segregate in highly concentrated clusters. Alkali metals are beneficial at low concentrations, where they homogenize the halide distribution, but at higher concentrations, they form recombination-active second-phase clusters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Thermal Variance Investigation and Scintillation Mechanisms of Cs 2 LiLaBr 6-x Cl x :Ce (CLLBC) and Cs 2 LiYBr 6 :Ce (CLYB)

We perform an investigation into the scintillation processes and performance of elpasolites Cs 2 LiLaBr 6-x Cl x :Ce (CLLBC) and Cs 2 LiYBr 6 :Ce (CLYB) using a thermal cycle over a range of -20 to +50º C. At 10º increments, we acquire data with both a waveform digitizer and charge-integrating electronics. We identify decay components and evaluate decay times, thermal neutron gamma-equivalent energy (GEE), and pulse shape discrimination (PSD) performance. Results are compared to common Cs 2 LiYCl 6 :Ce (CLYC).

36 MATERIALS SCIENCE↗
DOE OSTI2015

Response of Cs 2 LiYCl 6 :Ce (CLYC) to High Energy Protons

Cs 2 LiYCl 6 :Ce (CLYC) is a promising new inorganic scintillator for gamma and neutron detection. As a gamma-ray detector, it exhibits bright light output and better resolution and proportionality of response than traditional gamma-ray scintillators such as NaI. It is also highly sensitive to thermal neutrons through capture on 6 Li, and recent experiments have demonstrated sensitivity to fast neutrons through interactions with 35 Cl. The response of CLYC to other forms of radiation has not been reported. We have performed the first measurements of the response of CLYC to several-hundred MeV protons. We have collected digitized waveforms from proton events, and compare to those produced by gammas and thermal neutrons. Finally, we discuss the potential for pulse shape discrimination between them.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Preliminary Evaluation of Cesium Distribution for Wet Sieving Process Planned for Soil Decontamination in Japan - 13104

For the purpose of decontaminating radioactive cesium from a huge amount of soil, which has been estimated to be 1.2x10{sup 8} m{sup 3} by excavating to a 5-cm depth from the surface of Fukushima Prefecture where a severe nuclear accident occurred at TEPCO's power generating site and has emitted a significant amount of radioactive materials, mainly radioactive cesium, a wet sieving process was selected as one of effective methods available in Japan. Some private companies have demonstrated this process for soil treatment in the Fukushima area by testing at their plants. The results were very promising, and a full-fledged application is expected to follow. In the present study, we spiked several aqueous samples containing soil collected from an industrial wet sieving plant located near our university for the recycling of construction wastes with non-radioactive cesium hydroxide. The present study provides scientific data concerning the effectiveness in volume reduction of the contaminated soil by a wet sieving process as well as the cesium distribution between the liquid phase and clay minerals for each sub-process of the full-scale one, but a simulating plant equipped with a process of coagulating sedimentation and operational safety fundamentals for the plant. Especially for the latter aspect, the study showed that clay minerals of submicron size strongly bind a high content of cesium, which was only slightly removed by coagulation with natural sedimentation (1 G) nor centrifugal sedimentation (3,700 G) and some of the cesium may be transferred to the effluent or recycled water. By applying ultracentrifugation (257,000 G), most of submicron clay minerals containing cesium was removed, and the cesium amount which might be transferred to the effluent or recycled water, could be reduced to less than 2.3 % of the original design by the addition of a cesium barrier consisting of ultracentrifugation or a hollow fiber membrane. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Effect of Annealing in a Ferromagnetic State on the Structure of an Fe–18 at % Ga Alloy

The atomic structure of the iron–gallium alloy containing 18 at % Ga has been studied by X-ray diffraction. The samples were annealed in the paramagnetic (T > T{sub C}) and ferromagnetic (T < T{sub C}) state. In the first case, the structural state was fixed by quenching from the annealing temperature into water; in the second case, the structural state was obtained by slow cooling. The structural studies of the single-crystal samples were conducted on a four-circle X-ray diffractometer at room temperature. From the X-ray diffraction data, it follows that the alloy, independently on the heat treatment, contains B2 clusters, i.e., locally ordered regions with the CsCl-type structure observed in alloys of iron with silicon (to 10 at % Si) and aluminum (7 at % Al) before. In addition to the B2‑clusters, regions with the D0{sub 3} short-range order are observed in the quenched sample; the sizes of these regions significantly increases after annealing in the ferromagnetic state, i.e., a long-range order forms. The relation of the fine structural changes in the alloy due to various heat treatments with its magnetoelastic and magnetostriction properties is discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Characterization of Infrequent Samples from the Concentration, Storage, and Transfer Facility: F-Area Pump Pit 3 (FPP-3) Sump Sample: December 2021 Sample

In December 2021, SRR-E sent an ~185 mL sample identified as FPP-3 from a F-Area pump pit sump to SRNL for analysis. The sample was pale yellow in color and contained a small amount of suspended solids visually estimated to be less than 1% by volume. SRNL analysis indicated that the sample contained 4.4 E+05 dpm/mL Cs-137, 6.2 E+05 dpm/mL total beta activity, 9.3 E+02 dpm/mL beta activity following cesium removal, and below detectable levels of alpha activity following cesium removal. In addition, the sample contained 0.015 M free OH- and 947 μg total organic carbon/mL.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗