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Empirical error field control at JET in preparation of ITER start-up
No full textThis work reports on error field identification and control studies carried out at JET and insights on the development of the empirical EF controller for ITER. The empirical EF controller has been included in the JET real-time central controller following the execution of the non-disruptive compass scan method (Paz-Soldan C. et al., Nuclear Fusion 62 (2022) 126007), which allowed the identification of the EF source and the currents for error field compensation. When testing the empirical EF controller, born locked n = 1 modes have been observed to spin-up and a lower density regime has been explored in the 1.8 MA plasma current, 2.1 T toroidal magnetic field scenario than otherwise achievable. These experimental results demonstrate the benefits of EF correction. In preparation of EF correction studies in ITER, the empirical EF controller for ITER has been developed and integrated in the plasma control system database
Experimental analysis of flow boiling heat transfer in multimicrochannel evaporators
Get PDFThis paper provides an experimental analysis of flow boiling heat transfer in four finned evaporators with different aspect ratio and heated length have been tested. R245fa was the refrigerant chosen as working fluid for its good thermal characteristics. The imposed heat flux at the footprint covered a range from 30 to 330 kW/m2, while the fluid mass fluxes within the channel varied in a range between 17 and 225 kg/m2 s. The hydraulic diameters of the investigated evaporators were 1.15 mm and 2.09 mm, with aspect ratio (channel width/channel height) respectively of 0.3 and 0.72. Thanks to the measuring apparatus, heat transfer data were collected and then processed to calculate the local heat transfer coefficients, using the fin array heat transfer model. These local values of the heat transfer coefficient were then compared with those calculated from existing correlations for mini-micro channels flow boiling and the Mean Absolute Percent Error was finally assessed
Preliminary Configuration of a Robotic Arm for Pipeline Maintenance in the DTT Reactor
No full textThe maintenance of the DTT nuclear fusion reactor will be operated by a remote handling system which includes a number of specifically designed manipulators and robotic arms. This work aims to disclose the preliminary consideration for the design of a robotic system intended to handle pipes that must be periodically substituted in port 4 of the vacuum vessel. As the port appears as a narrow duct with a trapezoidal section, the arm must satisfy strict requirements in term of incumbrance and, at the same time, it must ensure the capability to remove and reposition the pipes which are displaced al around the perimeter of the section. The configuration is analyzed considering the geometrical constraints and the requirements for the workspace. The paper proposes a first design for the manipulator and shows the obtained workspace
Techno-Economic Assessment of Electrolytic Hydrogen Production for Refuelling Stations: Case Studies in Italy
No full textIn this paper a technical-economic feasibility study of electrolytic hydrogen production plants from non-programmable renewable sources (PV, wind) is presented. Grid-connected configurations in three different locations (North, Centre and South) in Italy have been analysed by considering different electrolysis technologies (alkaline electrolysis and solid oxide electrolysis) and by applying different plant management strategies
The Renewable Energy Communities: An Innovative Application to a Small Mountain Italian Municipality
No full textRenewable Energy Communities are novel virtuous models that aim to increase the penetration of renewable production technologies and ensure, at the same time, sustainable social and economic development. The recent European policy framework defined the Renewable Energy Communities as new actors in the electricity market and as entities sharing common goals in terms of sustainability. This paper investigates a case study based on a small mountain municipality in southern Italy. Results showed that the self-consumption and the benefit deriving from the incentivization of the shared energy generate the most relevant incomes. Then, two different strategies for the maximization of these two terms were proposed. Furthermore, the capacity expansion of the photovoltaic generation system was investigated, to align the local municipal policies to the goals of the Italian National Energy and Climate Plan
Advancements in the Genetic-Driven Optimisation of the Few-Group Structures for Lead Fast Reactors Analysis
No full textThe definition of the few-group structure for the analysis of fast spectrum reactors is still an open issue in reactor physics.Recent works have demonstrated that heuristic search algorithms, such as the evolutionary ones, are promising techniques for choosing the group boundaries.In this work, some advancements in this field are reported in the frame of lead fast reactors analysis, thanks to the development of a flexible, application-independent genetic a lgorithm.The exploration of the optimal group structures for the EU ALFRED core design is carried out by coupling the genetic algorithm with the FRENETIC nodal diffusion c ode, w hich h as b een d eveloped w ith t he computationally efficient si mulation of li quid-metal co oled re actors.Th e se arch fo r th e ne arly-optimal few-group representation is carried out by comparing the output of FRENETIC with the reference keff, flux and power density computed with the Serpent Monte Carlo code.Two possible chromosomic representations of the group structures are introduced and tested in the genetic optimisation process, showing different convergence performances
CO2 Conversion into Methane Over Ru/CeO2 Catalysts Prepared From Different Metal Ion Precursors
No full textAnthropogenic CO2 from aerospace cabin, or CO2 from outdoor atmosphere, such as the Martian atmosphere, may be converted into methane and water by the Sabatier reaction. Ru-based materials are suitable catalysts for methanation due to their high activity and selectivity. A previous study of a Ru/CeO2 catalyst prepared by one-pot hydrothermal synthesis from metal nitrate solutions, showed good activity for CO2 methanation with very high selectivity towards CH4 against CO (98 % at 350 °C), and high stability over time-on-stream, appearing as a promising and reliable Sabatier catalyst for in-situ resource utilization of CO2. In this study, four Ru/CeO2 catalysts were synthesized by one-pot hydrothermal method starting from different metal ions precursors, such as ruthenium(III) chlorine or nitrosyl nitrate salts, and cerium(III) nitrate or ammonium cerium(IV) nitrate salts. The catalytic tests showed that the nature of the metal precursor strongly affects the catalytic performances of the Ru/CeO2 system. The two catalysts prepared starting from RuCl3 showed higher activity than those prepared from the most used Ru(NO)(NO3)3 precursor, whereas one formulation produced an inactive material. The time-on-stream test (TOS), carried out for 40 hours in the range of 300-500 °C, revealed no activity nor selectivity loss. To understand the effect of the precursor nature on the material, a deep physical-chemical characterization of samples is needed. Some preliminary results on the surface morphology and Ru reducibility and dispersion obtained by XRD, BET-BJH, H2-TPR and H2-TPD, RAMAN and XPS are reported
Advanced Studies for the Dynamics of High Brightness Electron Beams with the Code MILES
Get PDFHigh brightness electron beams enable a wide spectrum of applications ranging from short wavelength radiation sources to high gradient wakefield acceleration. The rich dynamics that are intrinsic in charged particles accelerated in complex systems require a careful description in the analysis and design of a given machine, particularly regarding its stability. Numerous computer codes are in use by the accelerator community for such purposes. In particular, MILES is a simple tracking code we have developed that allows fast evaluations of collective effects in RF linacs. In this paper we extend the simple models previously developed to describe specific, diverse applications that can benefit from the fast simulation tools developed in MILES. Examples of this kind include particle driven acceleration schemes in a plasma where driver and witness beams propagate in the "comb"pulse-train configuration. Specifically, we investigate the self-induced fields excited within the X-band rf-linac stage of EuPRAXIA@SPARCLAB. Further, we discuss additional advanced topics such as resistive wall wakefield effects in planar FEL undulators and their impact on the radiation emitted
Direct radiative capture calculations on 56Fe
No full textThe theoretical description of the 56Fe neutron induced reaction cross sections is the subject of many studies within the nuclear data community. Based on these studies, issues were discovered in the evaluated cross sections of the 56Fe(n,γ) reaction. Those issues were addressed by implementing changes in the ENDF/B-VIII.0 evaluation. The aim of this work is to provide a physical interpretation for these changes by exploring the direct radiative capture mechanism for 56Fe. For the calculations, a dedicated code (PDIX) was utilized. The first results of the direct capture cross section of 56Fe are presented and discussed
Performance, Reliability and Economy of DFIGs for Micro-hydropower Applications: A Case Study
No full textToday, the Doubly Fed Induction Generator (DFIG) is widely used in wind power systems, thanks to its great versatility in regulation. In the last two decades, DFIGs diffused also in large hydropower applications, and more recently there is an increasing interest in micro-hydroelectric applications. To evaluate technical, economical and reliability aspects of the latter, a tool has been developed on purpose. An accurate mathematical model, including the losses of the real machine in operating conditions, has been developed and validated with experimental data. The proposed model, integrated with the calculation of reliability and cost parameters, has been applied to a paradigmatic real case study of a micro-hydroelectric power generator. With a DFIG, the reliability is increased with respect to other conventional solutions. Indeed, the Mean Time Between Failure (MTBF) of the whole system results 38% higher. As to the economy, the system allows savings between 20% and 35% over the whole lifecycle, with respect to the conventional solution. The obtained results show the economic feasibility and reduced maintenance needs of a DFIG for micro-hydroelectric applications