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Neutron spectrometry of a 241Americium-Boron neutron source using the NCT-WES single-moderator neutron spectrometer
Full text link241Americium-boron (α,n) neutron sources have been produced for various application from nuclear industry to well logging or radiation protection. Compared to 241Americium–beryllium sources their specific emission rate is lower, but their spectrum is narrower, and their production cycle uses boron, which is less toxic than beryllium. Very few data are available in literature about the energy distribution of this neutron source: the 2001 version of Standard ISO 8529-1 reported a reference spectrum derived from 1970s data, exhibiting a single peak from about 1 to 6 MeV. Other spectra are available in recent works from PTB and NPL, based on high-resolution spectrometers and Bonner spheres. ENEA Frascati owns a 241Am-B neutron source with nominal emission rate 3.5 × 106 s−1. Knowing its spectrum is important, as this source is used to feed the HOTNES (Homogeneous Thermal Neutron Source) facility. A spectrometry experiment was organized relying on the recently developed NCT-WES neutron spectrometer. Belonging to the family of the Single Moderator Neutron Spectrometers, NCT-WES is a convenient alternative to Bonner spheres as it derives the whole spectrum from a single exposure. The experimental data were elaborated in comparison with the existing literature spectra. As a main results of the study, the spectrum of the ENEA 241Am-B neutron source nearly perfectly agrees with that derived at NPL
Measurement of tritium production in the helium cooled pebble bed test blanket module mock-up at JET during DTE2
Full text linkQuite often, detectors for measuring nuclear performance and radiation quantities of relevance in fusion experiments are requested to withstand harsh working conditions due to intense neutron and gamma radiation fields. High temperature constitutes a further harsh element in some locations of the machine, where it is necessary to perform some on-line measurements, as expected in the breeding blanket. This is an essential component in future fusion power plants to provide tritium self-sufficiency and its performance must be continuously monitored. Some Test Blanket Modules (TBMs) will be installed in ITER to provide the first experimental data to validate the predictions on tritium production and recovery. In the meantime, within EUROfusion program, the mock-up of the Helium Cooled Pebble Bed Test Blanket Module (HCPB TBM), previously used for the TBM experiment at the Frascati Neutron Generator (FNG), had been installed at JET to test some detectors and for benchmarking numerical codes used for breeding blanket assessment during DTE2 campaign. A diamond detector, calibrated to measure the tritium production through neutron detection inside the HCPB TBM mock-up, was tested during some plasma pulses of the DTE2 campaign at JET. The main outcome is that, as far as neutron emission rate is below 1015 s−1, neutrons are properly detected along the plasma discharge evolution by TBM diamond detector, consistently with the JET neutron monitor KN1. Moreover, the amount of tritium measured (E) is 1.40 × 10–12 tritons per source neutron and the comparison with MCNP radiation transport simulation (C) gives a ratio C/E = 0.77. Such measurements, considered promising, and their comparison with calculations are discussed in the present work. Criticalities emerged are analyzed and some improvements proposed with the main purpose of speeding up signal processing to make the system capable of working at higher plasma neutron emission rates
I Neuropterida italiani nel progetto di community science di iNaturalist: prospettive e confronti con i database nazionali ufficiali
No full textIn questa comunicazione vengono presentati in dettaglio i risultati di questo triennio di osservazioni sulla piattaforma iNaturalist, mettendo in risalto il valore di questa modalità di collaborazione tra comunità scientifica e cittadinanza attiva per integrare ed arricchire le conoscenze sviluppate negli anni dagli specialisti che si sono dedicati allo studio faunistico italiano di questi insetti
Gravure-Printed Anodes Based on Hard Carbon for Sodium-Ion Batteries
Full text linkPrinted batteries are increasingly being investigated for feeding small, wearable devices more and more involved in our daily lives, promoting the study of printing technologies. Among these, gravure is very attractive as a low-cost and low-waste production method for functional layers in different fields, such as energy, sensors, and biomedical, because it is easy to scale up industrially. Thanks to our research, the feasibility of gravure printing was recently proved for rechargeable lithium-ion batteries (LiBs) manufacturing. Such studies allowed the production of high-quality electrodes involving different active materials with high stability, reproducibility, and good performance. Going beyond lithium-based storage devices, our attention was devoted on the possibility of employing highly sustainable gravure printing for sodium-ion batteries (NaBs) manufacturing, following the trendy interest in sodium, which is more abundant, economical, and ecofriendly than lithium. Here a study on gravure printed anodes for sodium-ion batteries based on hard carbon as an active material is presented and discussed. Thanks to our methodology centered on the capillary number, a high printing quality anodic layer was produced providing typical electrochemical behavior and good performance. Such results are very innovative and relevant in the field of sodium-ion batteries and further demonstrate the high potential of gravure in printed battery manufacturing
Overview of the EUROfusion Tokamak Exploitation programme in support of ITER and DEMO
Full text linkWithin the 9th European Framework programme, since 2021 EUROfusion is operating five tokamaks under the auspices of a single Task Force called ‘Tokamak Exploitation’. The goal is to benefit from the complementary capabilities of each machine in a coordinated way and help in developing a scientific output scalable to future largre machines. The programme of this Task Force ensures that ASDEX Upgrade, MAST-U, TCV, WEST and JET (since 2022) work together to achieve the objectives of Missions 1 and 2 of the EUROfusion Roadmap: i) demonstrate plasma scenarios that increase the success margin of ITER and satisfy the requirements of DEMO and, ii) demonstrate an integrated approach that can handle the large power leaving ITER and DEMO plasmas. The Tokamak Exploitation task force has therefore organized experiments on these two missions with the goal to strengthen the physics and operational basis for the ITER baseline scenario and for exploiting the recent plasma exhaust enhancements in all four devices (PEX: Plasma EXhaust) for exploring the solution for handling heat and particle exhaust in ITER and develop the conceptual solutions for DEMO. The ITER Baseline scenario has been developed in a similar way in ASDEX Upgrade, TCV and JET. Key risks for ITER such as disruptions and run-aways have been also investigated in TCV, ASDEX Upgrade and JET. Experiments have explored successfully different divertor configurations (standard, super-X, snowflakes) in MAST-U and TCV and studied tungsten melting in WEST and ASDEX Upgrade. The input from the smaller devices to JET has also been proven successful to set-up novel control schemes on disruption avoidance and detachment
Self-Cleaning Solar Mirror Coatings: From the Laboratory Scale to Prototype Field Tests
Full text linkFeatured Application: This work could be applied for producing self-cleaning solar mirrors. In this study, a low-cost, scalable and robust process is proposed as an innovative method for coating solar mirrors with a self-cleaning, transparent in the full solar range and versatile material based on auxetic aluminum nitrides, previously obtained at the laboratory scale. This work presents the scaling-up of the fabrication process from the laboratory to prototypal scale and the preliminary results of outdoor self-cleaning solar mirror field tests in the demonstrative concentrating solar power (CSP) plant ENEASHIP located in Casaccia (Rome) ENEA Research Center. Prototypes with a size of 50 × 40 cm have shown stability in external conditions: no coating degradation occurred during the test campaign. Their washing restores the initial reflectance affected by soiling and the self-cleaning performance allows for the utilization of a reduced quantity of water for cleaning operations with respect to the uncoated glass of back surface mirrors. A similar self-cleaning AlN coating could be utilized on other solar components affected by soiling, such as the glass envelopes in heat-collecting elements, PV panels and other parts where a self-cleaning performance combined with an optical one is required
Metabolic engineering of crocins and picrocrocin apocarotenoids in potato group phureja
Full text linkThe stigmas of Crocus sativus accumulate the exclusive apocarotenoids crocin and picrocrocin, which are dried and desiccated to make commercial saffron. In addition to providing characteristic organoleptic qualities, saffron apocarotenoids are valuable compounds in the pharmaceutical and health industries. Previously, we developed Desirée potato tubers enriched with these apocarotenoids which also showed increased potential benefits for human health. In the current study, Solanum tuberosum (S. tuberosum) Group Phureja 01H15 which accumulates high levels of zeaxanthin, was engineered to produce saffron apocarotenoids to increase the levels of these metabolites in potato tubers using a construct namely O6, which contains the CsCCD2L, UGT74AD1, and UGT709G1 genes necessary for the biosynthesis of crocin and picrocrocin under the control of the patatin promoter. Here, we obtained transgenic S. tuberosum Group Phureja 01H15 lines with high concentrations of crocins and picrocrocin (up to 3.648 mg/g DW, 2.345 mg/g DW, respectively), which were up to 10 and 3 times higher than those obtained in the Desirée background, respectively. Furthermore, we performed transcriptome analyses of tubers from Desirée and 01H15 wild type and carrying O6 construct. Differentially expressed gene analysis revealed transcript changes not only on tuber carotenoid and apocarotenoid genes but also in other related pathways, suggesting a possible role in isoprenoid metabolism remodeling. Thus, this heterologous system serves as a robust platform for the production of these valuable metabolites
Effects of Differential Displacements Between the Ground Anchors in Suspension Bridges
Full text linkA simple model to evaluate the effects of relative displacements between the ground anchors of a suspension bridge is proposed. An equation system is defined, which allows for the evaluation of the structural response under a general displacement set of the ground anchor points. Then, the most interesting and likely cases are analyzed in detail with reference to a suspension bridge having geometrical and mechanical characteristics typical of a long-span bridge. A simple procedure for the assessment of variation in cable stress is also given, which can be used to choose the optimum values for stress in cables under dead loads, as a percentage of their strength. The results obtained showed that expected movements do not significantly impact the structure in its lifetime and that the effects become negligible for very long-span bridges. Finally, the results obtained can be easily used for the condition monitoring of suspension bridges
Recent advance progress of HL-3 experiments
Full text linkSince the first plasma realized in 2020, a series of key systems on HL-3 (known as HL-2M before) tokamak have been equipped/upgraded, including in-vessel components (the first wall, lower divertor, and toroidal cryogenic/water-cooling/baking/glow discharge systems, etc.), auxiliary heating system of 11 MW, and 28 diagnostic systems (to measure the plasma density electron temperature, radiation, magnetic field, etc.). Magnet field systems were commissioned firstly for divertor plasma discharges. During the 2nd experimental campaign of HL-3 tokamak, several great progresses have been achieved. Firstly, the successful operation with plasma current larger than 1 MA was achieved under a divertor configuration. Secondly, the advanced divertor concept with two distinct snowflake configurations was realized. It is found that the distribution of ion saturation current and heat flux on bottom plate becomes wide due to magnetic surface expansion, demonstrating the advantage of such configuration in the heat flux mitigation. In addition, using the combination of NBI, ECRH and LHCD, the standard sawtoothing high confinement mode of megampere plasma was firstly accessed on the HL-3. The successful commissioning of HL-3 is beneficial for the initial operation of ITER
Stability analysis of plasma waves driven by runaway electrons in tokamak hot plasmas
Full text linkThe local stability analysis of plasma waves driven by runaway electrons (REs) has been performed considering hot plasma Maxwellian background, with electron and ion temperatures of the order of 1 keV. It is shown that hot plasma waves, namely electron plasma waves (EPWs) and ion Bernstein waves (IBWs) can be driven unstable by RE at their coalescence frequency via Cherenkov resonance by RE with energy distribution peaked at about 8 MeV. A skew-normal distribution is used as a model of the RE energy distribution. The EPW and IBW couples of waves occur between any successive ion-cyclotron harmonics frequencies nf ci, above the lower hybrid resonance. At their confluence, the perpendicular group velocity vanishes and significant RF emissions are expected. The frequency gap between two successive confluences is ∼f ci. Groups of RF line emissions, separated by almost constant frequency gap ∼f ci/2 are detected during various quiescent runaway plasma discharges in the FTU tokamak. The analysis of a specific discharge suggests that the frequencies of the line emissions observed and the frequencies occurring at the EPW-IBW confluences are in reasonable agreement. A possible explanation of the line emissions with ∼f ci/2 gap in terms of nonlinear mode coupling is proposed