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Advanced reactor technologies are being considered for the next-generation of nuclear power plants. These plants are designed to have a smaller footprint, run more efficiently at higher temperatures, have the flexibility to meet specific power or heating needs, and have lower construction costs. This paper offers a perspective on molten salt reactors, promoted as having a flexible fuel cycle and close-to-ambient pressure operation. A complexity introduced by reducing the reactor footprint is that it may require low-enriched fuel for efficient operation, available from enrichment of the feed salt or by reusing actinides from existing used nuclear fuel (UNF). Recycling UNF has the potential to reduce high-level waste, if done correctly. Release limits from UNF processing are stringent, and processes for waste reduction, fission gas trapping, and stable waste-form generation are not yet ready for commercial deployment. These complex processes are expensive to develop and troubleshoot because the feed is highly radioactive. Thus, fuel production and supply chain development must keep abreast of reactor technology development. Another aspect of reactor sustainability is the non-fuel waste streams that will be generated during operation and decommissioning. Some molten salt reactor designs are projected to have much shorter operational lifetimes than light-water reactors: less than a decade. A goal of the reactor sustainability effort is to divert these materials from a high-level waste repository. However, processing of reactor components should only be undertaken if it reduces waste. Economic and environmental aspects of sustainability are also important, but are not included in this perspective.

In this paper, a novel experimental setup to quantify the particle deposition during a lithium-ion battery thermal runaway (TR) is proposed. The setup integrates a single prismatic battery cell into an environment representing similar conditions as found for battery modules in battery packs of electric vehicles. In total, 86 weighing plates, positioned within the flow path of the vented gas and particles, can be individually removed from the setup in order to determine the spatial mass distribution of the deposited particles. Two proof-of-concept experiments with different distances between cell vent and module cover are performed. The particle deposition on the weighing plates as well as the particle size distribution of the deposited particles are found to be dependent on the distance between cell vent and cover. In addition, the specific heat capacity of the deposited particles as well as the jelly roll remains are analyzed. Its temperature dependency is found to be comparable for both ejected particles and jelly roll remains. The results of this study help researches and engineers to gain further insights into the particle ejection process during TR. By implementing certain suggested improvements, the proposed experimental setup may be used in the future to provide necessary data for simulation model validation. Therefore, this study contributes to the improvement of battery pack design and safety.

The advantages of fast-spectrum reactors consist not only of an efficient use of fuel through the breeding of fissile material and the use of natural or depleted uranium, but also of the potential reduction of the amount of actinides such as americium and neptunium contained in the irradiated fuel. The first aspect means a guaranteed future nuclear fuel supply. The second fact is key for high-level radioactive waste management, because these elements are the main responsible for the radioactivity of the irradiated fuel in the long term. The present study aims to analyze the hypothetical deployment of a Gen-IV Sodium Fast Reactor (SFR) fleet in Spain. A nuclear fleet of fast reactors would enable a fuel cycle strategy different than the open cycle, currently adopted by most of the countries with nuclear power. A transition from the current Gen-II to Gen-IV fleet is envisaged through an intermediate deployment of Gen-III reactors. Fuel reprocessing from the Gen-II and Gen-III Light Water Reactors (LWR) has been considered. In the so-called advanced fuel cycle, the reprocessed fuel used to produce energy will breed new fissile fuel and transmute minor actinides at the same time. A reference case scenario has been postulated and further sensitivity studies have been performed to analyze the impact of the different parameters on the required reactor fleet. The potential capability of Spain to supply the required fleet for the reference scenario using national resources has been verified. Finally, some consequences on irradiated final fuel inventory are assessed. Calculations are performed with the Monte Carlo transport-coupled depletion code SERPENT together with post-processing tools.

In this study, Distribution of Relaxation Times (DRT) was successfully demonstrated in the analysis of the impedance spectra of High-Temperature Polymer Electrolyte Membrane Fuel Cells (HT-PEMFC) doped with phosphoric acid. Electrochemical impedance spectroscopy (EIS) was performed and the quality of the recorded spectra was verified by Kramers-Kronig relations. DRT was then applied to the measured spectra and polarization losses were separated on the basis of their typical time constants. The main features of the distribution function were assigned to the cell’s polarization processes by selecting appropriate experimental conditions. DRT can be used to identify individual internal HT-PEMFC fuel cell phenomena without any a-priori knowledge about the physics of the system. This method has the potential to further improve EIS spectra interpretation with either equivalent circuits or physical models.

Herein, guidelines are provided for the dispersion of conductivity additive in nickel‐manganese‐cobalt‐oxide‐based lithium‐ion battery (LIB) cathodes with respect to its influence on electrochemical performance. The contrasting design strategies and operating conditions applicable to high‐power and high‐energy cathodes lead to significant differences in performance limiting factors for the respective microstructures. Hence, a generalization of the optimum dispersion of the conductivity additive that enhances cell performance in all cases is not possible. In this work, four distinct distributions of conductivity additive agglomerate/aggregate sizes resulting from varying mixing conditions are investigated with respect to their compatibility with cathode microstructures intended for different LIB applications with the help of spatially resolved electrochemical simulations. It is found that in the case of high‐power cathodes, wherein ionic transport is the dominant performance limiting factor, a more significant proportion of agglomerates that are bigger in size leads to improved diffusion and intercalation conditions. Conversely, in the case of high‐energy electrodes wherein the conductivity additive content is minimized, a larger fraction of smaller aggregates, produced by the fragmentation of the agglomerates during the mixing process are essential to ensure sufficient electrical conductivity.

The average antimony concentration in municipal solid waste is estimated to be about 10-60 ppm. Thermodynamical models predict a volatile behavior for antimony compounds, yet literature mass balances show that about 50% of the antimony input remains in the grate ashes. This fact can be explained by the formation of thermally stable antimonates in the fuel bed due to interactions with alkali or earth-alkali metals. Thermogravimetric experiments revealed an increased thermal stability for antimony oxide in presence of oxygen and calcium oxide. Spiking experiments on the test incinerator TAMARA showed that chlorination processes have a strong effect on antimony volatilization whereas high fuel-bed temperatures and addition of antimony oxide only have a moderate effect. In the grate ashes, antimony shows a pH-depending leaching property, which is typical for anionic species. This fact supports the thesis that antimony is present in the grate ashes in an anionic speciation.

AbstractUpgrading bio-oils for the production of transport fuel and chemicals is a challenge that has recently attracted a lot of attention. As one of the most prominent approaches, hydrodeoxygenation (HDO) was used in this work to upgrade the light phase of a pyrolysis oil produced from straw in the bioliq® pilot plant in Karlsruhe. A mild hydrotreatment was performed in a batch autoclave at 250 °C under hydrogen atmosphere (8.0 MPa at room temperature) in the presence of various nickel-based catalysts using different loadings and supports. Their catalytic performances, measured in term of hydrogen consumption, were similar but inferior to Ru/C (used as benchmark). The oxygen content was significantly decreased in the upgraded oils (20–26 wt%) as result of hydrodeoxygenation reactions and of the repartition of more apolar compounds in the upgraded oil. Using gas chromatography, the typical biomass platform molecules were detected and some reaction trends were identified. The conversion of phenol and the product selectivity was different whether this molecule was investigated in the pyrolytic mixture or as model compounds, indicating that the complex composition of the light phase or the probable deactivation of the catalyst plays a significant role. Quantitative 1H-NMR analysis was a useful method for gaining an overview about the reactivity of the different molecular functional groups present in the bio-oil.