GEN-IV LFR development: Status & perspectives

Since Lead-cooled Fast Reactors (LFR) have been conceptualized in the frame of Generation IV International Forum (GIF), great interest has focused on the development and testing of new technologies related to Heavy Liquid Metal (HLM) nuclear reactors. In this frame, ENEA developed one of the larger European experimental fleet of experimental facilities aiming at investigating HLM thermal-hydraulics, coolant chemistry control, corrosion behavior for structural materials, and at developing components, instrumentations and innovative systems, supported by experiments and numerical tools. The present work aims at highlighting the capabilities and competencies developed by ENEA so far in the frame of the liquid metal technologies for GEN-IV LFR. In particular, an overview on the ongoing R&D experimental program will be depicted considering the actual fleet of facilities: CIRCE, NACIE-UP, LIFUS5, LECOR and HELENA. CIRCE (CIRColazione Eutettico) is the largest HLM pool facility presently in operation worldwide. Full scale component tests, thermal stratification studies, operational and accidental transients and integral tests for the nuclear safety and SGTR (Steam Generator Tube Rupture) events in a large pool system can be studied. NACIE-UP (NAtural CIrculation Experiment-UPgraded) is a loop with a HLM primary and pressurized water secondary side and a 250 kW power Fuel Pin Simulator working in natural and mixed convection. LIFUS5 (lithium for fusion) is a separated effect facility devoted to the HLM/Water interaction. HELENA (HEavy Liquid metal Experimental loop for advanced Nuclear applications) is a pure lead loop with a mechanical pump for high flow rates experiments. LECOR (LEad CORrosion) is a corrosion loop facility with oxygen control system installed. All the experiment actually ongoing on these facilities are described in the paper, depicting their role in the context of GEN-IV LFR development

An investigation on the effect of different multi-step heat treatments on the microstructure, texture and mechanical properties of the DED-produced Ti-6Al-4V alloy

This work deals with the effect of different heat treatments on directed energy deposition (DED)-produced Ti- 6Al-4V samples. Annealing treatments at 1050 ◦C followed by different cooling rates were conducted to allow a complete recrystallization of the microstructure and remove the columnar prior-β grains, thus increasing the overall isotropy of the material. An agine treatment at 540 ◦ C was also performed for further microstructural stabilization. The microstructures, textures and mechanical properties were then assessed. Due to the heat treatments, greatly differing microstructures were achieved in an equiaxed grain morphology. However, a “grain memory” effect was detected which resulted in the grains size increasing along the height of the samples. This effect was correlated to the intrinsic prior-β grain width variation along Z on the as-printed specimens, typical of the DED technology. Electron backscatter diffraction analyses proved that the intensity of the preferential di- rections increased after the heat treatments, likely due to the crystallographic variant selection mechanisms taking place when the samples cool down from the annealing temperature. This effect is also influenced by the significant difference in terms of prior-β grains sizes between the heat-treated and the as-printed specimens. To sum up, a complete homogenization of the material via heat treatment above the β-transus temperature proved to be challenging. In fact, the data suggest that the intrinsic texture-related anisotropy granted by the manufacturing process is very difficult to be eliminated

Effect of Aging and Cooling Path on the Super β-Transus Heat-Treated Ti-6Al-4V Alloy Produced via Electron Beam Melting (EBM)

This work focuses on the effect of different heat treatments on the Ti-6Al-4V alloy processed by means of electron beam melting (EBM). Super beta-transus annealing was conducted at 1050 degrees C for 1 h on Ti-6Al-4V samples, considering two different cooling paths (furnace cooling and water quenching). This heat treatment induces microstructural recrystallization, thus reducing the anisotropy generated by the EBM process (columnar prior-beta grains). Subsequently, the annealed furnace-cooled and water-quenched samples were aged at 540 degrees C for 4 h. The results showed the influence of the aging treatment on the microstructure and the mechanical properties of the annealed EBM-produced Ti-6Al-4V. A comparison with the traditional processed heat-treated material was also conducted. In the furnace-cooled specimens consisting of lamellar alpha+beta, the aging treatment improved ductility and strength by inducing microstructural thickening of the alpha laths and reducing the beta fraction. The effect of the aging treatment was also more marked in the water-quenched samples, characterized by high tensile strengths but limited ductility due to the presence of martensite. In fact, the aging treatment was effective in the recovery of the ductility loss, maintaining high tensile strength properties due to the variation in the relative number of alpha/alpha' interfaces resulting from alpha' decomposition. This study, therefore, offers an in-depth investigation of the potential beneficial effects of the aging treatment on the microstructure and mechanical properties of the EBM-processed super beta-transus heat-treated Ti-6Al-4V alloy under different cooling conditions

Notes from the Suburb: the Image of Helsinki in the works by Kjell Westö

My doctoral thesis aims at analysing the suburbs of Helsinki as the urban space where the social, economic, cultural and linguistic transformations of the Finnish post-war society took place. Starting with the neo-marxist discourse elaborated by Marshall Berman in his essay "All that is solid melts into air", and taking into account contributions from the neo-marxist school, such as Pierre Bourdieau's, Terry Eagleton's and Rickard Graneau's, my thesis explores a selection of the works by the Finnish-Swedish writer Kjell Westö (1961), where the transformations of Helsinki during the second half of the century seem to reflect the country's opening to post-war capitalism. After a survey about Finnish modern history,my study focuses on the linguistic contraposition between the Finnish-speaking majority and the the Swedish-speaking minority as it has evolved during the Nineteenth and Twentieth century, trying to re-consider the concept of official language as a reliable means to help different communities to live side by side in the same space

“Chiamalo come diavolo vuoi” – l’affermazione della lingua degli immigrati nella letteratura svedese contemporanea

During the last decade, a new generation of writers with foreign background have appeared in Swedish Literature. The major feature of their works is the use of invandrarsvenska, the “immigrant Swedish”, a language widely outspread in the suburbs of Stockholm, Malmö and Göteborg. As scholars have pointed out, this “dialect” can be regarded both as an interim language spoken by immigrants unable to express themselves in fluent Swedish, or as a sociolect used by second generation immigrants, who deliberately speak with broken Swedish. After a brief outlook of the history of immigration in Sweden, the analysis concentrate on two short stories by Alejandro Lleiva Wenger and on the novel Ett öga rött by Jonas Hassen Khemiri, where immigrant Swedish is primarily used as slang. The last part is devoted to Khemiri’s second novel Montecore, and to Marjaneh Bakhtiari’s Kalla det vad fan du vill, where the writers describe the situation of their family in the suburbs of Stockholm and Malmö, giving special attention to the interim language spoken by their parents. This new generation has opened the way to a new urban realism, both linguistic and social, and has given us a critical portrait of contemporary Sweden

AI: profili giuridici. Intelligenza Artificiale: criticità emergenti e sfide per il giurista

The research aims at exploring the main legal issues triggered by the implementation of Artificial Intelligence systems, with a view to identifying possible solutions for regulators and lawmakers at national and supranational level. The study moves from a comprehensive overview covering the existing soft law instruments, the core areas captured in academic speculation and the latest developments in case law. It then separately addresses selected sensitive issues that should be on public and private policymakers’ agenda, most notably: the governance of AI; the impact of AI systems on public law; the relationship between AI systems and private and criminal law as well as procedural law. For each of these areas, the research analyzes how the rise of AI systems calls into question well established legal categories and which remedies lawmakers and regulators should take into account to reconcile the need to foster technological developments and that of protecting fundamental rights