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HTGR TRISO Fuel and Graphite Waste Management Strategies
No full textThis paper presents a review of possible high-temperature gas-cooled reactor (HTGR) fuel and graphite cycle back-end routes performed in the Euratom GEMINI 4.0 project based on previous European, International Atomicc Energy Agency, Nuclear Energy Agency, and diverse national research programs. It considers different variants of tristructural-isotropic (TRISO) fuel (enriched uranium, Pu, Th/233U fissile and fertile to fissile cycles, with oxide or oxicarbide fuel material options) for block-type cores. It identifies the remaining research and development issues. As the Finnish ONKALO® (Posiva Oy) repository is currently almost operable (i.e. operating license application submitted by Posiva), being therefore the first high-level waste disposal facility worldwide, its waste acceptance criteria are taken as a reference for the direct disposal of HTGR fuel elements. Spent fuel management for HTGRs is strongly impacted by the large graphite and coating volumes compared to the small portion of the fissile kernel. Therefore, a separation of the fuel compacts from the graphite block has been investigated. Disposal of spent fuel compacts separately from the graphite blocks is indeed expected to significantly reduce the HLW volumes. Processes for separating the TRISO particles from the compacts are also considered, as well as the packages for disposal of compacts or TRISO particles. For the direct disposal or disposal of separated compacts or particles, the corrosion leach resistance of the fuel kernels and of the TRISO coating layers has a crucial impact on the performance assessment of TRISO fuel disposal. Specific leach and corrosion tests on irradiated TRISO particles and fuel compacts are indispensable for establishing an optimized disposal concept. An ultimate step of separation can be to extract the fuel kernels from the TRISO coatings. It can be considered as a head-end step for reprocessing, the feasibility of which is examined. On the other hand, irradiated graphite management is a specific challenge for all graphite-moderated reactors due to the large associated volume, the specific contamination, and the degradation caused by neutron irradiation. Long-lived activation products, such as 14C and 36Cl, lead to the categorization of irradiated graphite as an intermediate-level waste in most countries. Therefore, treatment methods for reducing and/or stabilizing such isotopes for achieving a lower waste category, at a much lower disposal cost, are assessed. Reuse and refabricating options for irradiated graphite would be an interesting strategy toward a closed HTGR graphite cycle.</p
Introducing OpenTextile-NIR: Near-infrared hyperspectral imaging and photography dataset for optical identification of textiles
No full textThis dataset presents the first open-access collection of near-infrared hyperspectral imaging (NIR-HSI) data for the optical identification of textiles, with a focus on supporting research in sensor-based textile sorting and recycling. The dataset comprises hyperspectral images, RGB photographs, and detailed metadata, including fibre composition and colour, for 71 post-industrial textile samples, collected in Finland. Over 11 million spectra are included in the hyperspectral images, with more than 6 million annotated, providing a robust foundation for machine learning and data analysis. In addition, we provide a single representative NIR spectra and RGB value for each sample in order to accommodate classic spectroscopic analysis.Used garments were sourced from a partner company specializing in end-of-life textile management, with ground truth information on fibre composition obtained from suppliers. Small pieces of each garment were measured using Specim SWIR 3 hyperspectral camera and photographed with high-resolution mobile phone camera (Samsung Galaxy A52). The dataset is organized into folders containing raw and processed data, including ENVI-format hyperspectral images, RGB images, as well as CSV files with mean spectra, mean RGB values, and sample metadata. An example Python script is provided to facilitate data access and processing.Potential reuse scenarios include classification of textiles by material or colour, prediction of natural fibre content, image segmentation, algorithm development for spectral classification, and use as a reference spectral library. The dataset’s comprehensive structure and open availability address the limitations of previous research, which often relied on small or non-public datasets, and is intended to accelerate advances in optical identification technologies for textile recycling
From Leaves to Breezes: Machine learning based prediction of nitrogen dioxide concentration from surrounding urban greenery and meteorological, spatial, and traffic characteristics in Berlin, Germany
No full textThis study compares two machine learning models, a Random Forest (RF) and a spatial Graph Neural Network (GNN), for predicting nitrogen dioxide (NO) concentrations across diverse urban conditions in Berlin, Germany. Therefore, both models use information on local land-use characteristics, meteorological conditions, and seasonal greenery, which enables a post-hoc analysis of high-concentration scenarios under varying environmental factors. Unlike most previous approaches to air-pollution estimation, this study explicitly considers the interaction between urban greenery and its seasonal variation. The analysis is based on a self-curated, high-resolution site-level environmental dataset that captures hourly NO observations from sixteen monitoring stations across Berlin in 2023 with detailed land-use, traffic, and architectural data obtained from the Berlin Geoportal. This dataset is supplemented with multiple meteorological records from the Deutscher Wetterdienst (DWD). While both models achieve comparable accuracy (R 0.6), the GNN shows a tendency toward less variation of predictive accuracy across test sites, suggesting potential spatial robustness. For explainability, only the RF model allows for local interpretability via Shapley values, which indicate that urban greenery helps mitigate NO levels depending on seasonal changes in leaf area. However, additional statistical testing does not support this observed trend. Beyond the conducted assessment, this research contributes a comprehensive environmental dataset that links air quality, land-use, and meteorological variables at hourly resolution. This resource supports future investigations into how environmental and spatial factors jointly influence pollutant dispersion and decomposition in urban environments
CeOx-functionalized Pd nanoparticles on single-walled carbon nanotubes for alkaline hydrogen oxidation reaction
No full textThe sluggish kinetics of hydrogen oxidation reaction (HOR) in alkaline electrolytes highlight the strong need to develop next-generation catalyst materials for anion-exchange membrane fuel cells (AEMFC) anodes. In this study, CeOx is sequentially deposited on Pd nanoparticles supported on single-walled carbon nanotubes (SWNT) via atomic layer deposition (ALD). The obtained Pd@CeOx SWNT16 ALD cycles catalyst shows an excellent alkaline HOR performance with a specific exchange current of 166 mA mg−1Pd. This is three times higher than the commercially available Pd catalyst and the highest among reported Pd/CeOx catalyst materials with different CeOx overlayer coverages. By combining the X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and high-resolution scanning transmission electron microscopy, we confirm that the activity improvement is due to the highly conductive SWNT support enabling the fabrication of high surface area Pd clusters and CeOx overlayer. These methods reveal that the oxidation state of Ce is varying from Ce3+ to Ce4+ in relation to the CeOx overlayer thickness and the number of ALD cycles. Density functional theory calculations show that the presence of Ce/CeOx increases the diversity and population of Pd active sites with improved activity in its vicinity leading to enhanced overall catalytic performance. Moreover, this work provides a new perspective to develop highly active alkaline HOR catalysts for AEMFC
A state-of-the-art review of R&D for the supercritical water-cooled reactor technology. Part II materials & chemistry
No full textThis document presents a summary of the most relevant research and development (R&D) carried out to support the development of the only generation IV water-cooled reactor endorsed by the Generation IV International Forum (GIF).The coolant of the proposed reactor operates at supercritical water conditions, allowing for an increase in thermodynamic efficiency of the plant and the production of high-grade process heat. Several collaborations have been established to support this technology under the GIF umbrella as well as through other international avenues; as a result, the development work is bolstered by a collective effort between numerous R&D institutions across Asia, Europe, and North America. The Joint European Canadian Chinese development of Small Modular Reactor Technology (ECC-SMART) collaborative project was established to encompass the design and pre-licensing requirements as well as a roadmap demonstrating the safe operation of the supercritical water small modular reactor (SCW-SMR). One of the main challenges in the material and component aspect is the selection and qualification of a fuel cladding material that can withstand supercritical water conditions (beyond 374 °C and 22.1 MPa). The aim of the materials testing work package (WP2) in the ECC-SMART project is to achieve a deep understanding of the corrosion behavior of selected candidate cladding materials. Over 750 corrosion specimens were tested including those under nominal SCW-SMR operating conditions and also at simulated accident conditions. This article summarizes the findings from the study of corrosion behavior of non-irradiated and pre-irradiated candidate materials and from the study of the effect of chemistry and changes in the chemical properties of SCW.</p
Analysis of elastic and plastic behaviour in untreated pine wood under scratch test loads combining X-ray computed tomography and finite element simulations
No full textWood is an anisotropic material, which affects its performance under different loading conditions. To understand the origin of surface failures occurring in wood under mechanical disintegration loads, an accurate investigation of its elastic and plastic behaviour is required. This study introduces a methodology that integrates experimental scratch testing, X-ray micro-computed tomography (μCT), and finite element simulations to examine the elastic and plastic deformation and failure behaviour of untreated pine wood under scratch loading. In the existing literature, scratch testing is primarily employed to assess coating adhesion or material abrasion resistance; its use for probing the mechanical response of wood remains limited. In the present study, scratches were applied to pine specimens in the radial, tangential, and longitudinal directions of wood using a diamond indenter under constant normal loads perpendicular to the scratched surface. The permanent residual depths measured by μCT were compared with FE-predicted deformations. The selected methodology enables quantification of the relationship between wood structure, loading conditions, and scratch performance. The results demonstrated that the regions with higher density favoured elastic deformation, whereas the residual scratch depth, reflecting plastic deformation, provided a reliable indicator of scratch resistance, exhibiting higher scratch resistance for the higher density wood. In particular, the wood with higher density showed residual depths in the range of 53–144 µm in radial direction scratches, whereas the less dense wood showed values between 90 and 300 µm. μCT imaging also revealed detailed deformation mechanisms and fracture pathways that develop under scratch-type loading. By coupling μCT with FE modelling for wood scratch mechanics, the work deepens the understanding of how wood microstructure responds to different scratch loading conditions. The findings can serve as a scientific reference for future experimental and numerical investigations of scratching, cutting and other disintegration loads in untreated wood and wood-based composites at the microscale.</p
A Review of Public Funding for Agri-Food Exports, 2020–2025
No full textThis report examines the public funding supporting Finnish food exports and internationalization from 2020 to 2025. The study maps key funding sources – including Business Finland, European structural funds, the Rural Development Fund, the European Maritime, Fisheries and Aquaculture Fund (EMFAF), and EU promotion programs – and analyzes their support in fostering food sector growth. The analysis highlights the multi-stage export pathway for food companies, from local business development to international market entry and scaling, emphasizing the complementary roles of innovation funding, regional development, and sectoral collaboration. The report focuses on two themes: export promotion and internationalization, and food tourism. Results show that 48.2 million euros in public support were granted, with the majority directed at companies and also to research and education organisations. Municipalities, city actors and non-profit organizations had a smaller share of the funding. The study also addresses the challenges of data comparability and the need for unified terminology and impact metrics. Recommendations include improving data systems, harmonizing concepts, and developing better impact assessment tools to support the ambitious national goal of doubling food exports by 2031
Superbases as Organocatalysts in Low Temperature Glycolytic Depolymerization of Polyethylene Terephthalate (PET)
No full textChemical recycling offers a prospective solution for valorizing the vast amount of diverse polyethylene terephthalate (PET) waste generated from various streams. Rigid and flexible packaging such as bottles, and films, or textiles, optionally containing also comonomers like polypropylene terephthalate (PPT) and polybutylene terephthalate (PBT), are essential materials to be considered. In this study, low temperature depolymerization of PET was investigated by implementing glycolysis as the chemical recycling method. In glycolysis of PET, the polymer is depolymerized in excess ethylene glycol and presence of catalyst into bis(2-hydroxyethyl) terephthalate (BHET) monomer. The monomer can be re-utilized as feedstock for the manufacturing of recycled virgin-like PET. Herein we report utilization of novel mTBN guanidine superbase (mixture of two isomers, 7-methyl-1,5,7-triazabicyclo-[4.3.0]non-5-ene & 5-methyl-1,5,7-triazabicyclo-[4.3.0]non-6-ene) as efficient organocatalyst for glycolysis of virgin and post-consumer PET materials. Three guanidine compounds were screened as catalyst under various conditions and their efficiency was compared to zinc acetate, which is a conventionally applied transesterification catalyst. All superbases achieved high PET conversions of over 90 % at low reaction temperature of 140 °C within 2 h, while Zn(OAc) 2 showed only 18 % conversion. Moreover, mTBN superbase was the most efficient by depolymerizing PET powder in just 20 min. Industrially viable conversions of over 90 % resulted in BHET monomer recovery of over 40 % determined by mass. Size-exclusion chromatography (SEC) results indicate that reaction temperature has significant influence on the depolymerization reaction depth. Furthermore, experiments with different PET feedstocks demonstrate the significance of materials’ surface area towards depolymerization efficiency.</p
Enzyme-Directed Assembly of Antiparallel Cellulose II Nanocrystals:Unraveling the Mechanism Beyond Spontaneous Crystallization
No full textHumans have long utilized cellulose II, known as regenerated cellulose, for fibers like rayon and Cupra and films like cellophane. While cellulose I, found in nature, consists of parallel molecular chains, cellulose II is characterized by the stable arrangement of molecules in an antiparallel orientation. Enzymatic synthesis of cellulose in vitro also affords cellulose II with various morphologies, from monolayer lamellae crystals to gels, but its formation mechanism remains obscure. Here, we demonstrate that cellodextrin phosphorylase (CDP) catalyzes the synthesis and orchestrates the antiparallel self-assembly of cellulose II nanocrystals, exceeding the paradigm of spontaneous crystallization. High-resolution structural analysis reveals CDP’s key role in dictating crystal size and alignment, bridging the gap between enzymatic catalysis and biodirected material architecture. Our research unveils a unique protein-templated assembly process for advanced cellulose materials, paving the way for enzyme-guided construction of next-generation functional nanostructures.</p
Scientific assessment for urban air mobility (UAM)
No full textThis review article is the revised and expanded version of the Scientific Assessment for UAM document that the urban air mobility (UAM) working group of the International Forum for Aviation Research (IFAR) developed at the request of the International Civil Aviation Organization (ICAO). The assessment began with a study of the industry landscape, which includes an overview of existing market studies, proposed aircraft designs and concepts, and potential paths for industry evolution. The subsequent scientific assessment, developed through cooperative efforts among international domain experts, captures 17 focus areas relevant to UAM. Each focus area presents opportunities for further research. The assessment was delivered to the ICAO in 2023. This revised and expanded version reflects the UAM domain’s status quo, incorporating the most recent developments and trends identified in 2024. Key takeaways include: the need for further study of the impact of autonomous systems on the industry; infrastructure requirements (including vertiports and weather sensing) to support the industry sector; and data requirements (covering domains such as cybersecurity, emissions, and safety) to ensure safe and scalable UAM operations.</p