scholarly journals Vortex Target: A New Design for a Powder-in-Gas Target for Large-Scale Radionuclide Production

Instruments ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 24 ◽  
Author(s):  
Gerrie Lange
Keyword(s):  
Large Scale ◽  
Gas Flow ◽  
Nuclear Reactions ◽  
Volume Ratio ◽  
Target Material ◽  
Thick Target ◽  
Beam Power ◽  
Design Work ◽  
Radionuclide Production ◽  
Gas Target

This paper presents a design and working principle for a combined powder-in-gas target. The excellent surface-to-volume ratio of micrometer-sized powder particles injected into a forced carrier-gas-driven environment provides optimal beam power-induced heat relief. Finely dispersed powders can be controlled by a combined pump-driven inward-spiraling gas flow and a fan structure in the center. Known proton-induced nuclear reactions on isotopically enriched materials such as 68Zn and 100Mo were taken into account to be conceptually remodeled as a powder-in-gas target assembly, which was compared to thick target designs. The small irradiation chambers that were modeled in our studies for powdery ‘thick’ targets with a mass thickness (g/cm2) comparable to 68Zn and 100Mo resulted in the need to load 2.5 and 12.6 grams of the isotopically enriched target material, respectively, into a convective 7-bar pressured helium cooling circuit for irradiation, with ion currents and entrance energies of 0.8 (13 MeV) and 2 mA (20 MeV), respectively. Current densities of ~2 μA/mm2 (20 MeV), induces power loads of up to 4 kW/cm2. Moreover, the design work showed that this powder-in-gas target concept could potentially be applied to other radionuclide production routes that involve powdery starting materials. Although the modeling work showed good convective heat relief expectations for micrometer-sized powder, more detailed mathematical investigation on the powder-in-gas target restrictions, electrostatic behavior, and erosion effects during irradiation are required for developing a real prototype assembly.

Computational fluid dynamics of rectangular external loop airlift reactor

2020 ◽  
Vol 18 (5-6) ◽  
Author(s):  
Shivanand M. Teli ◽  
Channamallikarjun S. Mathpati
Keyword(s):  
Large Scale ◽  
Lift Coefficient ◽  
Volume Ratio ◽  
Reynolds Stress Model ◽  
Airlift Reactor ◽  
Experimental Results ◽  
Turbulent Dispersion ◽  
Drag Forces ◽  
External Loop ◽  
Turbulent Models

AbstractThe novel design of a rectangular external loop airlift reactor is at present the most used large-scale reactor for microalgae culture. It has a unique future for a large surface to volume ratio for exposure of light radiation for photosynthesis reaction. The 3D simulations have been performed in rectangular EL-ALR. The Eulerian–Eulerian approach has been used with a dispersed gas phase for different turbulent models. The performance and applicability of different turbulent model’s i.e., K-epsilon standard, K-epsilon realizable, K-omega, and Reynolds stress model are used and compared with experimental results. All drag forces and non-drag forces (turbulent dispersion, virtual mass, and lift coefficient) are included in the model. The experimental values of overall gas hold-up and average liquid circulation velocity have been compared with simulation and literature results. It is seemed to give good agreements. For the different elevations in the downcomer section, liquid axial velocity, turbulent kinetic energy, and turbulent eddy dissipation experimental have been compared with different turbulent models. The K-epsilon Realizable model gives better prediction with experimental results.

scholarly journals The ISOLPHARM project: A New ISOL production method of high specific activity beta-emitting radionuclides as radiopharmaceutical precursors

2018 ◽  
Vol 48 ◽  
pp. 1860103 ◽  
Author(s):  
A. Andrighetto ◽  
F. Borgna ◽  
M. Ballan ◽  
S. Corradetti ◽  
E. Vettorato ◽  
...  
Keyword(s):  
Nuclear Reactions ◽  
Specific Activity ◽  
Isotope Separation ◽  
High Specific Activity ◽  
Target Material ◽  
Mass Range ◽  
Production Method ◽  
Radioactive Isotopes ◽  
Innovative Technology ◽  
On Line

The ISOLPHARM project explores the feasibility of exploiting an innovative technology to produce extremely high specific activity beta-emitting radionuclides as radiopharmaceutical precursors. This technique is expected to produce radiopharmaceuticals that are virtually mainly impossible to obtain in standard production facilities, at lower cost and with less environmental impact than traditional techniques. The groundbreaking ISOLPHARM method investigated in this project has been granted an international patent (INFN). As a component of the SPES (Selective Production of Exotic Species) project at the Istituto Nazionale di Fisica Nucleare–Laboratori Nazionali di Legnaro (INFN–LNL), a new facility will produce radioactive ion beams of neutron-rich nuclei with high purity and a mass range of 80–160 amu. The radioactive isotopes will result from nuclear reactions induced by accelerating 40 MeV protons in a cyclotron to collide on a target of UC[Formula: see text]. The uranium in the target material will be [Formula: see text]U, yielding radioactive isotopes that belong to elements with an atomic number between 28 and 57. Isotope separation on line (ISOL) is adopted in the ISOLPHARM project to obtain pure isobaric beams for radiopharmaceutical applications, with no isotopic contaminations in the beam or subsequent trapping substrate. Isobaric contaminations may potentially affect radiochemical and radionuclide purity, but proper methods to separate chemically different elements can be developed.

Study on Effective Radial Thermal Conductivity of Gas Flow through a Methanol Reactor

2015 ◽  
Vol 13 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Kun Lei ◽  
Hongfang Ma ◽  
Haitao Zhang ◽  
Weiyong Ying ◽  
Dingye Fang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Temperature Distribution ◽  
Large Scale ◽  
Gas Flow ◽  
Fixed Bed ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Particle Reynolds Number

Abstract The heat conduction performance of the methanol synthesis reactor is significant for the development of large-scale methanol production. The present work has measured the temperature distribution in the fixed bed at air volumetric flow rate 2.4–7 m3 · h−1, inlet air temperature 160–200°C and heating tube temperature 210–270°C. The effective radial thermal conductivity and effective wall heat transfer coefficient were derived based on the steady-state measurements and the two-dimensional heat transfer model. A correlation was proposed based on the experimental data, which related well the Nusselt number and the effective radial thermal conductivity to the particle Reynolds number ranging from 59.2 to 175.8. The heat transfer model combined with the correlation was used to calculate the temperature profiles. A comparison with the predicated temperature and the measurements was illustrated and the results showed that the predication agreed very well with the experimental results. All the absolute values of the relative errors were less than 10%, and the model was verified by experiments. Comparing the correlations of both this work with previously published showed that there are considerable discrepancies among them due to different experimental conditions. The influence of the particle Reynolds number on the temperature distribution inside the bed was also discussed and it was shown that improving particle Reynolds number contributed to enhance heat transfer in the fixed bed.

scholarly journals Enhanced production of 99Mo in inverse kinematics heavy ion reactions

2021 ◽  
Vol 252 ◽  
pp. 08003
Author(s):  
Justin Mabiala ◽  
Marcia R.D. Rodrigues ◽  
Georgios A. Souliotis ◽  
Victor E. Iacob ◽  
Ninel Nica ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Large Scale ◽  
Heavy Ion ◽  
Scale Production ◽  
Gas Cell ◽  
Enhanced Production ◽  
Gas Target ◽  
Large Scale Production ◽  
Cell Target ◽  
Catcher Foil

The reaction of a 100Mo beam at 12 MeV/nucleon impinging on a 4He gas-cell target was performed. The 99Mo alongside other coproduced isotopes were collected after the gas target on an aluminum catcher foil and their respective radioactivities were measured by offline γ-ray analysis. In this contribution, preliminary experimental results which are used to discuss the possibility of optimal large-scale production conditions of the produced radioisotopes are presented.

scholarly journals Prospective predictors of sustainment of multiple EBPs in a system-driven implementation context: Examining sustained delivery based on administrative claims

2021 ◽  
Vol 2 ◽  
pp. 263348952110578
Author(s):  
Anna S. Lau ◽  
Teresa Lind ◽  
Mojdeh Motamedi ◽  
Joyce H. L. Lui ◽  
Mary Kuckertz ◽  
...  
Keyword(s):  
Large Scale ◽  
Organizational Context ◽  
Scale Up ◽  
Volume Ratio ◽  
Organizational Factors ◽  
Self Report ◽  
Administrative Claims ◽  
Sustained Delivery ◽  
Cross Sectional ◽  
Program Leaders

Background System-driven scale-up of multiple evidence-based practices (EBPs) is an increasingly common method used in public mental health to improve care. However, there are little data on the long-term sustained delivery of EBPs within these efforts, and previous studies have relied on retrospective self-report within cross-sectional studies. This study identified prospective predictors of sustained EBP delivery at the EBP-, therapist-, and organizational-levels using survey and administrative claims data within a large-scale system-driven implementation effort. Methods 777 therapists and 162 program leaders delivering at least one of six EBPs of interest completed surveys assessing perceptions of EBPs and organizational context. These surveys were linked to administrative data to examine prospective predictors of therapists’ EBP delivery over 33 months. Results Five of the six EBPs implemented showed sustained delivery in the system, with volume varying by EBP. Although total EBP claim volume per therapist decreased over time, the volume ratio (ratio of EBP-specific claims to total EBP and non-EBP claims) stayed relatively stable. Multilevel models revealed that EBPs that required consultation, had unstructured content, higher therapist self-efficacy with the EBP, and more positive program leader perceptions of the EBP were associated with greater sustained volume and volume ratio of the EBP. Therapists who were trained in fewer EBPs, who were unlicensed, and who worked in agencies rated by program leaders as lower on organizational staff autonomy and stress showed greater sustained EBP volume and volume ratio. Finally, more direct service hours per week provided by therapist predicted greater sustained EBP volume, but lower volume ratio. Conclusions The results point to the importance of EBP, therapist, and organizational factors that may be targeted in implementation strategies to promote the sustainment of EBPs.

Ultrasonic Nondestructive Testing for In-Line Monitoring of Wire-Arc Additive Manufacturing (WAAM)

2020 ◽  
Author(s):  
Md Shahjahan Hossain ◽  
Hossein Taheri ◽  
Niraj Pudasaini ◽  
Alexander Reichenbach ◽  
Bishal Silwal
Keyword(s):  
Quality Assurance ◽  
Additive Manufacturing ◽  
Nondestructive Testing ◽  
Large Scale ◽  
Gas Flow ◽  
Complex Structure ◽  
Process Condition ◽  
Process Conditions ◽  
Ultrasonic Signals ◽  
Wire Arc Additive Manufacturing

Abstract The applications for metal additive manufacturing (AM) are expanding. Powder-bed, powder-fed, and wire-fed AM are the different kinds of AM technologies based on the feeding material. Wire-Arc AM (WAAM) is a wire-fed technique that has the potential to fabricate large-scale three-dimensional objects. In WAAM, a metallic wire is continuously fed to the deposition location and is melted by an arc-welding power source. As the applications for WAAM expands, the quality assurance of the parts becomes a major concern. Nondestructive testing (NDT) of AM parts is necessary for quality assurance and inspection of these materials. The conventional method of inspection is to perform testing on the finished parts. There are several limitations encountered when using conventional methods of NDT for as-built AM parts due to surface conditions and complex structure. In-situ process monitoring based on the ultrasound technology is proposed for WAAM material inspection during the manufacturing process. Ultrasonic inline monitoring techniques have the advantages of providing valuable information about the process and parts quality. Ultrasonic technique was used to detect the process condition deviations from the normal. A fixture developed by the authors holds an ultrasonic sensor under the build platform and aligned with the center of the base plate. Ultrasonic signals were measured for different process conditions by varying the current and gas flow rate. Features (indicators) from the radio frequency (RF) signal were used to evaluate the difference in signal clusters to identify and classify different build conditions. Results show that the indicator values of the ultrasonic signals in the region of interest (ROI) changes with different process conditions and can be used to classify them.

scholarly journals Solid Target System with In-Situ Target Dissolution

Instruments ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 14 ◽  
Author(s):  
William Z. Gelbart ◽  
Richard R. Johnson
Keyword(s):  
Target Material ◽  
Incident Beam ◽  
Chemistry Laboratory ◽  
Target System ◽  
Beam Power ◽  
New Approach ◽  
Target Station ◽  
Production Target ◽  
Design Construction

A significant number of medical radioisotopes use solid, often metallic, parent materials.These materials are deposited on a substrate to facilitate the cooling and handling of the targetduring placing, irradiation, and processing. The processing requires the transfer of the target to aprocessing area outside the irradiation area. In this new approach the target is processed at theirradiation site for liquid only transport of the irradiated target material to the processing area. Thedesign features common to higher energy production target systems are included in the targetstation. The target is inclined at 14 degrees to the beam direction. The system has been designed toaccept an incident beam of 15 to 16 mm diameter and a beam power between 2 and 5 kW. Thermalmodeling is presented for targets of metals and compounds. A cassette of five or 10 preparedtargets is housed at the target station as well as a target dissolution assembly. Only the dissolvedtarget material is transported to the chemistry laboratory so that the design does not requireadditional irradiation area penetrations. This work presents the design, construction, and modelingdetails of the assembly. A full performance characterization will be reported after the unit is movedto a cyclotron facility for beam related measurements.

scholarly journals Synergistic Effect and Characterization of Graphene/Carbon Nanotubes/Polyvinyl Alcohol/Sodium Alginate Nanofibrous Membranes Formed Using Continuous Needleless Dynamic Linear Electrospinning

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 714 ◽  
Author(s):  
Ting-Ting Li ◽  
Yanqin Zhong ◽  
Mengxue Yan ◽  
Wei Zhou ◽  
Wenting Xu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Synergistic Effect ◽  
Polyvinyl Alcohol ◽  
Sodium Alginate ◽  
Large Scale ◽  
Volume Ratio ◽  
Electrospinning Technique ◽  
Large Scale Preparation ◽  
Scale Preparation ◽  
Nanofibrous Membranes

In this study, a self-made continuous needleless dynamic linear electrospinning technique is employed to fabricate large-scale graphene (Gr)/carbon nanotubes (CNT)/polyvinyl alcohol (PVA)/sodium alginate (SA) nanofibrous membranes. The synergistic effect of Gr and CNT fillers in the PVA/SA membrane is explored in depth by changing the volume ratio (v/v) of Gr and CNT as 10:0, 8:2, 6:4, 4:6, 2:8, and 0:10. Microstructure, functional group, conductivity, and hydrophilicity of PVA/SA/Gr/CNT membranes was characterized. Results show that the linear electrode needleless electrospinning technique can be spun into 200-nm diameter fibers. The PVA/SA/Gr/CNT fibrous membrane has good hydrophilicity and thermal stability. A Gr/CN ratio of 6:4 possessed the optimal synergistic effect, which showed the lowest surface resistivity of 2.53 × 103 Ω/m2. This study will provide a reference for the large-scale preparation of nanofibrous membrane used as a artificial nerve conduit in the future.

Influence of CGD structure on burden descending behavior in COREX shaft furnace

2019 ◽  
Vol 116 (3) ◽  
pp. 304 ◽  
Author(s):  
Xingsheng Zhang ◽  
Zongshu Zou ◽  
Zhiguo Luo
Keyword(s):  
Large Scale ◽  
Gas Flow ◽  
Shaft Furnace ◽  
Three Dimensional ◽  
Interaction Force ◽  
Flow Patterns ◽  
Solid Flow ◽  
Reducing Gas ◽  
A New Technique ◽  
Actual Size

For improving the reducing gas flow in the center of a large-scale shaft furnace, the central gas distribution (CGD) device, a new technique, is proposed and installed in the shaft furnace. Because of its less-developed history, the solid flow in the shaft furnace with CGD is unclear. In this work, a three-dimensional cylindrical model of COREX-3000 shaft furnace in actual size is established based on DEM. Four types of burden, including pellet, lump ore, coke and flux, are taken into consideration in the model. The model is validated by experiment and then it is used to investigate the influence of CGD structure on solid flow patterns, burden descending velocity, interaction force and abrasive wear. The results show that the CGD structure has some effects on the solid flow patterns and burden descending velocity. As the CGD diameter increases, the interaction force between particles is decreased but the total abrasion energy on CGD is increased. As the CGD height increases, both the interaction force between particles and the total abrasion energy on CGD are decreased.

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