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Ensuring tritium fuel self-sufficiency while maintaining continuous and high-specification fuel flow to the tokamak via a low tritium inventory and controllable fuel cycle is a significant challenge to the STEP plant design. Effective and high-quality fuelling and exhaust design is required to sustain and control a stable plasma, whereas fuel sufficiency is required to prevent depletion of available tritium supply. Concerns regarding the lack of tritium availability preventing continuous tritium import are countered by breeding, where highly energetic neutrons from the core fusion reactions interact with lithium atoms suspended in the surrounding breeder blanket to produce tritium. The compact nature of STEP prohibits the integration of inboard breeder blankets posing a significant challenge for the design team looking to ensure more tritium is bred and made available than consumed within the core plasma. This paper outlines how purposeful technology selection and system architecting has converged on the outline of a conceivable and tritium-capable fuel cycle and breeder blanket design. Before introducing the STEP fuel cycle design outline and summarizing the approach undertaken to address the challenges facing plasma fuelling, key aspects of fuel self-sufficiency are discussed. This includes discussing a proposed helium-cooled liquid lithium breeder blanket and possible technology options for tritium extraction from lithium. Lastly, there is a brief process modelling overview, which emphasizes the central contribution of various employed modelling methods. Reflections on the presented fuel cycle design outline conclude that substantial development work is still required to realize a continuous tritium fuel cycle design and overcome the major challenges posed by tritium and lithium handling. Reflections on the presented breeder blanket design proposal conclude that while many substantial risks and blockers remain to achieve fuel self-sufficiency, high breeding ratios are expected to be achievable with a compact spherical tokamak configuration. Nonetheless, it is recognized that further consideration is required to ensure that the selection of liquid lithium as a breeder medium provides the overall simplest route to a self-sufficient and realizable design. This article is part of the theme issue 'Delivering Fusion Energy – The Spherical Tokamak for Energy Production (STEP)'. [ABSTRACT FROM AUTHOR]

The European DEMO (EU-DEMO) reactor studies within EUROfusion aim to develop a fusion power plant concept. The large tokamak device needs an auxiliary heating power which, at the present stage, is provided by the Electron Cyclotron (EC) heating system with up to 130 MW foreseen to reach different regions of plasma for heating, suppression of instabilities and the possibility to support ramp-up and ramp-down phases. The present conceptual design of the system is based on 2 MW coaxial-cavity gyrotron sources, a transmission line (TL) using both circular corrugated waveguides and quasi-optical evacuated multi-beam TLs, and mirror antennas located in the Equatorial Port. In order to create a modular system, the sources are grouped in 'clusters', whose powers are combined in the quasi-optical TL, up to the tokamak building, where they are split and routed as single waveguides. In the launcher, they are combined together again on the launching mirrors, to save space for the apertures in the Breeding Blanket. The present EC heating system has a certain flexibility to adapt to changing design guidelines. The development status of the system is presented. [ABSTRACT FROM AUTHOR]

In migratory animals, high mobility may reduce population structure through increased dispersal and enable adaptive responses to environmental change, whereas rigid migratory routines predict low dispersal, increased structure, and limited flexibility to respond to change. We explore the global population structure and phylogeographic history of the bar‐tailed godwit, Limosa lapponica, a migratory shorebird known for making the longest non‐stop flights of any landbird. Using nextRAD sequencing of 14,318 single‐nucleotide polymorphisms and scenario‐testing in an Approximate Bayesian Computation framework, we infer that bar‐tailed godwits existed in two main lineages at the last glacial maximum, when much of their present‐day breeding range persisted in a vast, unglaciated Siberian‐Beringian refugium, followed by admixture of these lineages in the eastern Palearctic. Subsequently, population structure developed at both longitudinal extremes: in the east, a genetic cline exists across latitude in the Alaska breeding range of subspecies L. l. baueri; in the west, one lineage diversified into three extant subspecies L. l. lapponica, taymyrensis, and yamalensis, the former two of which migrate through previously glaciated western Europe. In the global range of this long‐distance migrant, we found evidence of both (1) fidelity to rigid behavioural routines promoting fine‐scale geographic population structure (in the east) and (2) flexibility to colonise recently available migratory flyways and non‐breeding areas (in the west). Our results suggest that cultural traditions in highly mobile vertebrates can override the expected effects of high dispersal ability on population structure, and provide insights for the evolution and flexibility of some of the world's longest migrations. [ABSTRACT FROM AUTHOR]

Biphasic Li 2 TiO 3 –Li 4 SiO 4 ceramics have been proposed as advanced tritium breeder for solid-type breeding blankets of fusion reactors. However, the mechanism of tritium release from biphasic Li 2 TiO 3 –Li 4 SiO 4 ceramics remains to be elucidated. In this study, an integrated numerical model for tritium release from biphasic Li 2 TiO 3 –Li 4 SiO 4 ceramics was constructed for the first time. In the proposed model, besides the mass transfer steps for tritium release from single-phase ceramics (e.g. Li 2 TiO 3 and Li 4 SiO 4), a mass transfer step between the interfacial layers of Li 2 TiO 3 and Li 4 SiO 4 was also included to take into account the effect of two-phase interface in Li 2 TiO 3 –Li 4 SiO 4 ceramics. By using this model, numerical simulations of tritium release from Li 2 TiO 3 –Li 4 SiO 4 ceramics with different phase ratio and grain size were performed. The simulation results showed that the mass transfer of tritium atoms between the interfacial layers of Li 2 TiO 3 and Li 4 SiO 4 can effectively enhance tritium release from Li 4 SiO 4 in biphasic Li 2 TiO 3 –Li 4 SiO 4 ceramics. Furthermore, increasing phase ratio of Li 2 TiO 3 and decreasing grain size of Li 2 TiO 3 were both beneficial to tritium release from biphasic Li 2 TiO 3 –Li 4 SiO 4 ceramics at lower temperature. The modeling work consolidated the presumption that the two-phase interface could play an important role in the tritium release process of biphasic Li 2 TiO 3 –Li 4 SiO 4 ceramics. [ABSTRACT FROM AUTHOR]

Bright basal reflections from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) have been proposed to be consistent with permittivities characteristic of a wet material beneath the south polar layered deposits (SPLD). The characterization of a recently formed impact crater highlight the existence of a several meters thick ice‐poor layer associated to a unit blanketing a large portion of the SPLD. We revise the radar propagation model used to invert the basal permittivity by including a surficial thin layer. We find that the inverted basal permittivity is highly sensitive to the properties of such a layer, with solutions ranging from common dry rocks to an unambiguously wet base. We advocate toward a better characterization of the surficial cover to assess the wet or dry nature for the base, and possibly reconcile most of the literature on the topic. Plain Language Summary: A localized bright radar reflection has been detected from the base of the Southern Martian polar cap. This reflection has been attributed to salty water infiltrating the material present beneath the ice. However, this result is not yet reconciled with other radar analyses and a debate has emerged on how liquid brine could be sustained at Martian conditions. Recently a 5‐m thick layer of dust blanketing the surface of the ice cap has been detected from a recent crater excavation. This layer would act like a thin coating material that alters the apparent property of what is seen through a coated glass. At radar wavelengths, it can significantly modify the basal composition inferred from radar echoes. The bulk property of this layer is still unknown and a better characterization is necessary to inform the debate over a wet or dry base below the ice cap. Key Points: We re‐assess the radar inversion of the south polar layered deposits (SPLD) basal permittivity by incorporating the recently characterized dust layer mantling the iceThe inverted basal permittivity is highly sensitive to the property of the surficial dust layerBetter characterization of the dust layer is necessary in discriminating the nature of the SPLD bright basal reflector [ABSTRACT FROM AUTHOR]

The studies on the development of fusion–fission hybrid reactors (FFHR) have gained consensus in recent years as an intermediate step before fusion energy. This work proposes a possible approach to FFHRs based on the coupling of a Reversed Field Pinch fusion machine and a Molten Salt Subcritical fission test bed. The proposed test bed is characterized by the coexistence of a fast-neutron fission core and a dedicated thermal-neutron zone, allowing the performing of tritium breeding and actinides transmutation studies. The neutronic design solutions and the results obtained by the irradiation of FLiBe salt (inside the thermal-neutron zone) and of an actinide target (inside the core) are shown. The outcomes of the analysis reveal the potential of FFHR systems as breeding/burner systems. In particular, the results regarding tritium breeding are very encouraging as the system is demonstrated to be able to reach a very high Tritium Breeding Ratio. [ABSTRACT FROM AUTHOR]

Firefighting units in the Slovak Republic are well prepared for extinguishing fires of vehicles with internal combustion engines. However, the expansion of electromobility is also coming to Slovakia. It is essential to pay attention to this topic from the point of view of repression. This article deals with car fire blankets. The main objective is to verify and compare the effectiveness of extinguishing internal combustion engine vehicle (ICEV) fires and high-voltage traction battery (HTB) fires using car fire blankets. The effectiveness of a car fire blanket was determined based on the analysis of temperature drops during large-scale fire tests of ICEVs and HTBs. The temperature was recorded by four thermocouples. Two thermocouples were placed at 0.7 m from the ICEV and HTB; one thermocouple was placed in the interior of the ICEV and inside the HTB; one thermocouple was placed on the roof of the ICEV and the surface of the HTB. Subsequently, the results were compared based on temperature–time curves obtained from experimental measurements. Applying the car fire blanket to the ICEV fire caused a drop in temperature on all thermocouples. The most significant temperature drop was recorded in the interior of the vehicle. Specifically, the temperature dropped from 724 °C to 140 °C. However, the application of the car fire blanket had a different effect on the HTB fire. There was a minimal temperature change in the thermocouple on the right side at a 0.7 distance. The other thermocouples identified a slight increase in temperature. [ABSTRACT FROM AUTHOR]

Understanding the tritium breeding and release behavior of ceramic breeder is crucial for the parameter design of solid blanket in deuterium-tritium (D-T) fusion reactors. Lithium titanate (Li 2 TiO 3) is commonly considered an attractive candidate tritium breeder material. Defect types and densities formed by neutron irradiation at different energies result in diverse tritium release behaviors in Li 2 TiO 3. To understand the mechanism of high-energy neutrons on the tritium release of solid-state breeders, it is crucial to elucidate the tritium production and release behavior of Li 2 TiO 3 under 14 MeV fusion neutron irradiation. In this study, the high-intensity D-T fusion neutron source (HINEG-CAS) was employed to conduct tritium production experiments on Li 2 TiO 3 ceramic breeder samples. Tritium release experiment was also performed on irradiated Li 2 TiO 3 samples using the release system to obtain the temperature-dependent pattern of tritium release induced by fusion neutrons. The results indicated that a limited but visible amount of tritium was released at room temperature. Defect self-healing behavior at RT was seemly observed. The tritium release peak occurred at ∼673 K as the temperature increased. After continuous purging for 4 h at 1073 K, no residual tritium was observed in the irradiated sample, indicating successful collection through bubblers. The total radioactivity of released tritium amounted to 1866.4 Bq, predominantly in the form of tritiated water (HTO: 79.3%). Furthermore, the preliminary analysis of the mechanism behind tritium release has been provided as well. The investigation is conducive to the design optimization of the breeding blanket. • The tritium production and release experiments of Li 2 TiO 3 were conducted using 14 MeV fusion neutron irradiation. • A limited but clearly observable amount of tritium released at room temperature due to the defect self-healing behavior. • The peak of tritium release occurred at approximately 673 K and the primary form was identified as HTO (79.3%). • The influence of water vapor, sensitive tritium measurement method, and heating rate were essential for tritium release. [ABSTRACT FROM AUTHOR]

Large‐scale photocatalytic water‐splitting panel reactor system is developed and demonstrated its commercial feasibility. However, water scarcity is one of the leading challenges for the sustainable development of photocatalytic hydrogen generation in a well‐lit area. Here, a water harvesting form air‐photothermal water evaporation‐photocatalytic hydrogen evolution (AWPH) system is devised. The hybrid system comprising carbonized wood (CWx) combined with the hygroscopic salt ZnCl2 and Pt‐modified g‐C3N4 nanosheets (Pt‐CN) as a photocatalyst is developed, in which the carbonized wood has a vertical pore structure that can provide attachment sites for the hygroscopic salt. The water adsorbed by ZnCl2 is driven along the vertical pore channels to the photocatalyst due to the photothermal conversion effect. The bi‐phase interfaces of vapor/photocatalyst/hydrogen produced by the photothermal‐photocatalytic system significantly reduce the interface barrier and substantially lower the resistance to hydrogen transport. CW550 exhibited a water uptake of 0.56 g g−1 and hydrogen yield of 21.99 µmol cm−2 under 100 mW cm−2 illumination at a flow rate of 2 mL min−1 for 5 h and a half at atmospheric pressure. [ABSTRACT FROM AUTHOR]

The Chinese space station is a complex structure with large flexible appendages. Obtaining the on-orbit response characteristics of such a structure under different working conditions is a traditional and classic challenge in the field of dynamics. To address the on-orbit dynamics of the China Space Station, the basic equations for dynamic reduction, assembly and data recovery of linear and nonlinear substructures are derived based on the reduction and recovery theory, and a fast coupling analysis framework for flexible systems with nonlinear attachments is formed. This coupling analysis framework is adopted to quickly acquire the dynamic response of the China Space Station during in-orbit operation, thereby guiding the design. Taking SZ-15 radial docking to the Chinese Space Station as the object, the substructure of six nonlinear flexible arrays is reduced, the full flexible dynamic equation of the space station is assembled, and the response of each part of the flexible wing during the docking process is analyzed and recovered. By designing a reasonable and reliable flexible wing test scheme in-orbit, the acceleration at the root and top of the flexible wing during the docking of SZ-15 is obtained. The measured data in-orbit show that the acceleration analysis results of the typical parts of the flexible wing have a good agreement, which verifies the correctness of the fast coupling analysis framework of the flexible system. Hence, the dynamic coupling characteristics analysis of the main structure of the space station and the flexible wing based on this method can better guide the rationality of the design of the dynamic characteristics of the Chinese Space Station. [ABSTRACT FROM AUTHOR]

Groundwater‐surface water interactions (GSI) connect rivers and streams with riparian areas and the adjacent aquifer. Although these interactions exert a substantial control of quantity and quality of both groundwater and surface water, knowledge on GSI along rivers at the regional scale, particularly for inland waterways, is still limited. We investigated GSI along the river Moselle, an important federal inland waterway in Germany, by using radon and tritium to identify gaining (water flux from the aquifer to the surface water) and losing (water flux from the surface water to the aquifer) stream conditions, respectively. Gaining stream conditions were identified by continuously measuring radon along the river during boat surveys with a high spatial resolution (every 2 km) during intermediate (October 2020) and near low flow conditions (August/September 2021). The tritium concentrations in surface water and groundwater and the resulting tritium inventories were used to characterize losing stream conditions Monthly tritium inventories from 2017 to 2022 revealed a mean loss for the whole period of 20.3 % and a mean gain of 21.8%. Both were probably triggered by a combination of losing stream conditions and flood‐induced mass transfer of water from the aquifer back into the river as well as discharge fluctuations. At the investigated site Lehmen there were direct indications of an influence of surface water due to elevated tritium concentrations in the groundwater (up to 13.3 Bq L−1). Using radon mass balance modelling, good agreements of simulated versus measured radon data with respect to two groundwater end‐member scenarios were obtained during intermediate flow (Spearman's ρ: 0.97 and 0.99; MAE: 10.1 and 3.4 Bq L−1) and near low flow (Spearman's ρ: 0.97 and 0.99; MAE: 11 and 6.5 Bq L−1). Considerable groundwater inflow was limited to the meander of Detzem, where cumulated groundwater inflow of about 19 m3 s−1 (9.5% of total discharge) and 4.2 m3 s−1 (3.8% of total discharge) was simulated during intermediate and near low flow, respectively. However, the groundwater inflow was relatively low compared to alpine streams, for example. The study will help to better identify and quantify GSI at the regional scale and provide methodological guidance for future studies focusing on inland waterways. [ABSTRACT FROM AUTHOR]

The lognormal statistical distribution was used to present the reliable integrated data on the content of various physicochemical forms of tritium in air, natural water, and components of aquatic ecosystems at nuclear facility sites. Statistics of lognormal distributions took into account the left truncation, which reflects the effect of finite sensitivity of measurements. The statistics of lognormal distributions were used to obtain estimates for ecosystems of NPP sites at limited sets of data. Specific activities were estimated for various forms of tritium such as HTO (free water), TFWT (tissue free water tritium), and OBT (organically bound tritium). The measurement results show that the specific activity of tritium in the body in bound forms was, as a rule, higher than its specific activity in free water in the ambient environment. Equilibrium concentration ratios (CRs) (partition coefficients of hydrogen) ranged from 1 to about 20. The results obtained by the Radium Institute research team agree with those obtained by the researchers from Canada and France for the specific activity of tritium in different chemical forms in environmental samples. [ABSTRACT FROM AUTHOR]

Molten salt systems have become of growing interest in the energy industry due to a wide range of applications (concentrated solar power systems, energy storage, Generation IV fission reactors, and high magnetic field fusion reactors). Because of the high temperature that characterizes such materials, radiative heat transfer (RHT) may become a nonnegligible heat transfer mechanism in molten salt components. In this paper, an investigation of FLiBe RHT has been conducted, with a focus on Affordable, Robust, Compact (ARC)–class fusion reactors, a preconceptual design proposed by Commonwealth Fusion Systems and the Plasma Science and Fusion Center. This class of reactors largely employs FLiBe molten salt due to its thermal and neutronic properties. The reactor is characterized by high temperatures, and its 0.5-m-thick liquid immersion blanket is a component where RHT contribution to the temperature distribution is yet to be evaluated. Therefore, this study is the first work that quantifies the contribution of RHT in ARC-class reactor FLiBe systems. FLiBe optical property spectral-banding assessment is carried out, and the impact of RHT in FLiBe systems is assessed in operational ARC-class scenarios through computational fluid dynamics models by taking advantage of COMSOL® Multiphysics. Heat transfer, thermal-dependent properties, and buoyancy effects are considered in a comparison between scenarios with and without RHT modeling. The flow field in the tank is unaffected by RHT effects, even when considering buoyancy effects. The external layer of the vacuum vessel shows an average decrease in the temperature of 5.4 K and an average decrease in temperature on the surface in contact with the FLiBe tank of 8.1 K. Results indicate that for ARC-class reactors, RHT phenomena are negligible (<1% increase in heat transfer) in operational conditions. [ABSTRACT FROM AUTHOR]

To solve the main problems of designing a thermonuclear tokamak reactor, such as the experimental demonstration of quasi-stationary thermonuclear burning, generation of non-inductive quasi-stationary current; development of plasma technologies and materials of the first wall and divertor, the International Thermonuclear Experimental Reactor ITER is being designed, projects of DEMO demonstration reactors are being developed, and a Tokamak with Reactor Technologies TRT is being developed in Russia. The main components of the ITER (superconducting electromagnetic system (EMS) made of Nb3Sn and NbTi, the first wall of W coated with a low-Z material, systems for additional plasma heating, experimental modules of a breeder blanket, plasma control systems, etc.) and TRT (EMS of high-temperature superconductors, first wall options of W with B4C coating, TiB2–AlN composite and liquid metal lithium, additional heating and quasi-stationary non-inductive current drive systems, innovative divertor, experimental breeder and hybrid blanket modules, reactor-compatible diagnostics and remote plasma control systems, etc.) technology platforms are presented. The technological platforms of the ITER being under construction and the TRT being designed contain an almost complete, according to modern understanding, set of technologies for the future thermonuclear reactor. [ABSTRACT FROM AUTHOR]

This document is an editorial discussing advances in nuclear fusion energy and cross-cutting technologies. The current energy model, based on fossil fuels, is unsustainable and contributes to global warming. Nuclear fusion, specifically the use of breeding blankets, is a promising alternative energy source. The document highlights recent advancements in fusion technologies, such as the Helium-Cooled Pebble Bed (HCPB) and Water-Cooled Lithium Lead (WCLL) breeding blanket concepts. It also discusses safety systems, tritium permeation, and the development of fusion power plants. The editorial emphasizes the need for further research and development in these areas. [Extracted from the article]

The flow characteristics of purge gas helium in the pebble bed of the tritium breeding blanket are important in analyzing the tritium purging process and optimizing the design of the solid breeder blanket. Therefore, the flow characteristics of helium gas in randomly packed pebble beds are investigated experimentally with a focus on the analysis of the pressure loss distribution. The results show that gas velocity, bed dimension, and pebble diameters have an obvious influence on the helium flow characteristics in pebble beds. With the increase in the inlet helium gas velocity, the pressure drop gradient of helium in the pebble bed gradually increased. With increases in the pebble bed dimension, the pressure drop gradient of helium in the pebble bed gradually increased. With the increase in the pebble diameter, the pressure drop gradient gradually decreased. In addition, the effect of temperature on the pressure drop of helium in the pebble bed was also preliminarily investigated. The pressure drop gradient of the helium through the pebble bed obviously increased with the increase in the helium and the bed temperature. The experimentally obtained pressure loss characteristics can be used for the validation of the simulation of a blanket pebble bed and as input parameters in the thermo-hydraulic analysis of solid-tritium breeder blankets. [ABSTRACT FROM AUTHOR]

In a tritium-breeding blanket of a fusion reaction, helium, used as a tritium-purging gas, will purge the tritium breeder pebble beds to extract the tritium in blanket. The purge gas flow characteristics will affect the tritium extraction efficiency. The effect of the fixed wall on the pebble packing structures and purge gas flow characteristics was investigated by combining the discrete element method (DEM) and computational fluid dynamics (CFD) method. The results indicate that the fixed wall leads to a regular packing of the pebbles adjacent to the fixed wall in association with drastic fluctuations in the porosity of the pebble bed, which can affect the purge gas flow behaviors. Further analyses of helium flow behaviors show that the helium pressure in the pebble bed decreases in a linear manner along the flow direction, whereas the pressure drop gradient of helium increases gradually with an increase in the packing factor. The reduction in porosity in the pebble bed leads to a notable escalation in helium flow velocity. Concerning the direction perpendicular to the helium gas flow, the evolution of the cut-plane averaged velocity of helium is similar to that of the porosity, except in the region immediately adjacent to the wall. The pressure drop and flow characteristics obtained in this study can serve as input for the thermohydraulic analysis of the tritium blowing systems in the tritium-breeding blanket of a fusion reactor. [ABSTRACT FROM AUTHOR]

First generation commercial fusion energy plants are being designed to operate on a deuterium-tritium (D-T) fuel cycle. The fuel component tritium, a radioactive hydrogen isotope with a half-life of 12.3 years, and deuterium, a stable, naturally occurring constituent of water, are "burned" in a D-T plasma. To enable sustained, efficient commercial fusion energy plant designs, technology advancements are needed in the processes and engineered systems for tritium production (blanket breeding and extraction), and for its handling as a gas including isotopic-separation and impurity-removal processing. Modeling of the processes and improvements in accountancy methods will facilitate low in-process inventories of tritium for plant efficiencies and to meet any safety, environmental insult, and nonproliferation regulations that would be established. As the U.S. lead laboratory for tritium and light isotope science and technology, and for engineered processing systems for the nation's defense mission, the Savannah River National Laboratory is leveraging its competencies in the hydrogen gas handling, isotopic-separation, and purification technologies in the design/build of the Tokamak Exhaust Processing (TEP) system, the main processing system for the D-T fuel cycle used in ITER. The competencies and experiences used in these missions are applied in work with the U.S. Department of Energy in public-private partnerships to develop sustainable D-T fuel cycle designs to foster commercialization of fusion energy for the U.S. [ABSTRACT FROM AUTHOR]

Past waste-disposal activities at Naval Air Station Whiting Field (NASWF) have led to elevated concentrations of contaminants in the underlying sand and gravel aquifer. Contaminants include two of the most commonly detected chemicals in groundwater in many countries (benzene and trichloroethylene (TCE)) and the "forever chemicals" per- and poly-fluoroalkyl substances (PFAS) such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). A MODFLOW model (the Whiting Field Groundwater Model (WFGM)) was previously developed for NASWF and the surrounding area to simulate groundwater flow. To obtain insight into groundwater flow pathways for the identification of potential source areas, the MODPATH particle-tracking application was applied to the WFGM for three public supply wells and three monitoring wells at NASWF. The travel time to recharge areas was estimated using concentrations of the groundwater age-dating solutes tritium (as helium ingrowth) and chlorofluorocarbons detected in the monitoring wells. Simulated travel times agree with the groundwater ages and indicate that the calibrated WFGM reasonably represents groundwater flow velocities and pathways. The MODPATH simulations confirm suspected on-base source areas to explain chemical detection in the monitoring wells. In contrast, the particle-tracking simulations indicate that potential source areas to the public supply wells include both on- and off-base sources. This is important because PFAS chemicals can have multiple sources, including land application of sludge-based fertilizers. This approach that combines groundwater age dating with particle-tracking simulations can be applied at similar sites characterized by benzene-, TCE-, and PFAS-contaminated groundwater. [ABSTRACT FROM AUTHOR]

The relevance of the engineering and technical solutions implemented at the Branch of Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCh RAS), in the 1980s when designing a laboratory building with a vivarium and a nursery of specific pathogen-free (SPF) laboratory animals was discussed. SPF-status laboratory animals are used when performing non-clinical studies according to the OECD principles of Good Laboratory Practice (GLP). [ABSTRACT FROM AUTHOR]

Fluoride-salt-cooled high-temperature reactors (FHRs) are a promising reactor class that combines prominent attributes from the Gen-Ⅳ reactors, raising attractive interests of the international community. However, tritium control has been a major challenge in FHRs because of the neutron reactions of lithium. It's necessary to study the transport characteristics of tritium in the fluoride-salt-cooled high-temperature advanced reactor (FuSTAR) and to provide theoretical support for appropriate tritium control measures and safe operation of the FHRs. In this paper, the inclusive transport characteristics of production, graphite adsorption, diffusion, dissolution, and permeation on tritium in the primary loop are analyzed. The mathematical and physical model of the tritium transport phenomenon is established, and an analysis model of tritium transport characteristics is also developed. Then, the tritium transport characteristics in the FuSTAR primary loop are analyzed. The results show that the tritium in the FuSTAR primary loop mainly exists in the form of Diatomic Tritium (T 2), and it's found that Tritium Fluoride (TF) and T 2 are adsorbed by graphite after being generated in the core, and this process reaches saturation in about 150 Effective Full Power Days (EFPDs). It also indicates that almost 48% of tritium penetrates the secondary loop through the heat exchanger, and only about 3.8% of tritium is adsorbed on the core graphite. TF makes the corrosion of the heat exchanger and downcomer more serious. Finally, the safety of tritium transport in FuSTAR is conservatively estimated, with a tritium emission dose of 0.1674 mSv/a. This study can provide a theoretical reference for the structural design, tritium recycling, and radiation protection of FHRs. • A mathematical and physical model of the tritium transport phenomenon in FHR is established. • Tritium mainly exists in the form of T 2 in the primary loop of FuSTAR. • Tritium penetration and corrosion should be focused on the downcomer and PCHE. • The tritium release dose to the environment of FuSTAR is assessed. [ABSTRACT FROM AUTHOR]

Tritium permeation constitutes a key issue for the future EU-DEMO, especially in the Breeding Blanket (BB) where fusion energy must be delivered to the Primary Heat Transport System (PHTS) and where tritium must be bred. Currently, the mitigation strategy of the tritium permeation from BB into primary coolant is based on the adoption of anti-permeation barriers and on the operation of the Coolant Purification System (CPS). This system must ensure a tritium removal rate from the primary coolant equal to the BB permeation rate at a target tritium-specific activity inside the PHTS. In the case of the Water-Cooled Lithium Lead (WCLL) BB, water distillation was selected as the most promising technology for the primary coolant detritiation due to its intrinsic simplicity and safety. Nevertheless, power consumption was recognized as a relevant concern. For this reason, the present work aims at investigating possibilities to reduce power consumption of the water CPS implementing Heat Pump-Assisted Distillation (HPAD) concepts. To do this, a review of the HPADs developed in the chemical industry was carried out, and the best options for the water CPS were identified based on qualitative considerations. Then, a quantitatively assessment of the best solution in terms of power consumption and tritium inventory was performed with the commercial numerical tool Aspen Plus. Finally, the Mechanical Vapor Recompression (MVR) concept was recognized as the most promising solution, ensuring a power saving of around 80% while keeping a limited tritium inventory. [ABSTRACT FROM AUTHOR]

Li 4 SiO 4 ceramic pebble is deemed as the most attractive tritium breeder for fusion reactor blanket. In this work, we fabricated a novel Li 4 SiO 4 pebble with micrometer-scale pore structure by digital light processing to verify the feasibility of complex pore structure manufacturing for future breeders. The effects of processing parameters on printing accuracy, microstructure and mechanical properties of Li 4 SiO 4 pebbles were investigated. For synthesizing the pure Li 4 SiO 4 phase, the optimal stoichiometric ratio of Li 2 SiO 3 to Li 2 CO 3 was 1:1.09 in the premixed powder. The photosensitivity of dual-phase ceramic suspension was investigated according to an attenuation model, and the overgrowth was reduced to ∼50 μm by using the dimension formula. After optimizing the post-processing, the radial pore structure Li 4 SiO 4 pebbles with excellent crush load (50.3 N, standard deviation = 4.4 N) and suitable open porosity (18.3 %) can be yielded. This work provides a fresh solution to control the pore structure of tritium breeding pebbles in an unprecedented micrometer scale. [Display omitted] • Radial pore Li 4 SiO 4 pebble was designed, and fabricated by vat photopolymerization. • Dual-phase premixed powder (Li 2 CO 3 –Li 2 SiO 3) was used to yield high purity Li 4 SiO 4. • Dimension modal was built, and the overgrowth was effectively reduced to 54.1 μm. • Optimized post-process led to higher crush load (50.3 N) and proper microstructures. [ABSTRACT FROM AUTHOR]

This article discusses tritium concentrations in monthly precipitation in part of the Difficult-to-Return Zone in Namie Town during 2012–2021. The tritium concentrations, which were measured with a low background liquid scintillation counter after carrying out an enrichment procedure, fluctuated seasonally from 0.10 ± 0.02 to 0.85 ± 0.02 Bq L−1. This range of concentrations is concluded to not be unusual based on comparisons with the concentrations at other sites and estimates of the past range of the concentrations. Moreover, no significant variations in observed tritium concentrations were observed due to decommissioning work at the Fukushima Dai-ichi Nuclear Power Plant. These results contribute to understanding the background level of tritium concentration in precipitation before the oceanic discharge of treated water from the Fukushima plant. In addition, this article evaluates the amount of tritium supplied to the ocean by terrestrial rainwater pouring into the Pacific Ocean via Ukedo River, which flows through Namie Town; this information will contribute to the discussion on the impact of the oceanic discharge of treated water. [ABSTRACT FROM AUTHOR]

Plant stress is a significant challenge that affects the development, growth, and productivity of plants and causes an adverse environmental condition that disrupts normal physiological processes and hampers plant survival. Epigenetic regulation is a crucial mechanism for plants to respond and adapt to stress. Several studies have investigated the role of DNA methylation (DM), non-coding RNAs, and histone modifications in plant stress responses. However, there are various limitations or challenges in translating the research findings into practical applications. Hence, this review delves into the recent recovery, implications, and applications of epigenetic regulation in response to plant stress. To better understand plant epigenetic regulation under stress, we reviewed recent studies published in the last 5–10 years that made significant contributions, and we analyzed the novel techniques and technologies that have advanced the field, such as next-generation sequencing and genome-wide profiling of epigenetic modifications. We emphasized the breakthrough findings that have uncovered specific genes or pathways and the potential implications of understanding plant epigenetic regulation in response to stress for agriculture, crop improvement, and environmental sustainability. Finally, we concluded that plant epigenetic regulation in response to stress holds immense significance in agriculture, and understanding its mechanisms in stress tolerance can revolutionize crop breeding and genetic engineering strategies, leading to the evolution of stress-tolerant crops and ensuring sustainable food production in the face of climate change and other environmental challenges. Future research in this field will continue to unveil the intricacies of epigenetic regulation and its potential applications in crop improvement. [ABSTRACT FROM AUTHOR]

Research and development of the DEMOnstration power plant (DEMO) breeder blanket (BB) has been performed in recent years based on a predefined DEMO tritium breeding ratio (TBR) requirement, which determines a loss of wall surface due to non-breeding in-vessel components (IVCs) which consume plasma-facing wall surface and do not contribute to the breeding of tritium. The integration of different IVCs, such as plasma limiters, neutral beam injectors, electron cyclotron launchers and diagnostic systems, requires cut-outs in the BB, resulting in a loss of the breeder blanket volume, TBR and power generation, respectively. The neutronic analyses presented here have the goal of providing an assessment of the TBR losses associated with each IVC. Previously performed studies on this topic were carried out with simplified, homogenized BB geometry models. To address the effect of the detailed heterogeneous structure of the BBs on the TBR losses due to the inclusion of the IVCs in the tokamak, a series of blanket geometry models were developed for integration in the latest DEMO base model. The assessment was performed for both types of BBs currently developed within the EUROfusion project, the helium-cooled pebble bed (HCPB) and water-cooled lead–lithium (WCLL) concepts, and for the water-cooled lead and ceramic breeder (WLCB) hybrid BB concept. The neutronic simulations were performed using the MCNP6.2 Monte Carlo code with the Joint Evaluated Fission and Fusion File (JEFF) 3.3 data library. For each BB concept, a 22.5° toroidal sector of the DEMO tokamak was developed to assess the TBR and nuclear power generation in the breeder blankets. For the geometry models with the breeder blanket space filled only with blankets without considering IVCs, the results of the TBR calculations were 1.173, 1.150 and 1.140 for the HCPB, WCLL and WLCB BB concepts, respectively. The TBR impact of all IVCs and the losses of the power generation were estimated as a superposition of the individual effects. [ABSTRACT FROM AUTHOR]

Background: Hemerocallis citrina Baroni (Huang hua cai in Chinese) is a perennial herbaceous plant grown for its flower buds that are eaten fresh or dried and is known as the vegetarian three treasures. The nuclear genome of H. citrina has been reported, but the intraspecific variation of the plastome (plastid genome) has not yet been studied. Therefore, the panplastome of this species collected from diverse locations is reported here for the first time. Results: In this study, 65 H. citrina samples were resequenced, de novo assembled, and aligned with the published plastome of H. citrina to resolve the H. citrina panplastome. The sizes of the 65 newly assembled complete plastomes of H. citrina ranged from 156,048 bp to 156,263 bp, and the total GC content ranged from 37.31 to 37.34%. The structure of the complete plastomes showed a typical tetrameric structure, including a large single copy (LSC), a small single copy (SSC), and a pair of inverted repeat regions (IRA and IRB). Many nucleotide variants were identified between plastomes, among which the variants in the intergenic spacer region were the most abundant, with the highest number of variants concentrated in the LSC region. Based on the phylogenetic tree constructed using the ML method, population structure analysis, and principal component analysis (PCA), the panplastome data were subdivided into five genetic clusters. The C5 genetic cluster was mostly represented by samples from Qidong, Hunan Province, while samples from Shanxi and Shaanxi Provinces were classified into the C4 genetic cluster. The greatest genetic diversity was found in the C1 genetic cluster, and the greatest genetic distance between any two clusters was found between the C4 and C5 clusters. Conclusion: The resolution of the panplastome and the analysis of the population structure of H. citrina plastomes provide important data for future breeding projects and germplasm preservation. [ABSTRACT FROM AUTHOR]

Dwarfing and the selection of optimal plant types constitute the primary focus of sorghum breeding. However, the lack of clarity regarding the gene types associated with plant height genes Dw1-Dw4 in the primary breeding materials has led to increased plant heights in improved offspring of the same plant height type, resulting in unsatisfactory morphological traits. This study aimed to elucidate the gene types related to plant height in breeding materials, validate the regulatory mechanisms, and establish a material improvement system. The goal was to achieve molecular-marker-assisted dwarf breeding through the detection of plant height genes and the test cross verification of main Chinese sorghum materials. Using 38 main male sterile lines and 57 main restorer lines of grain sorghum as materials, three plant height genes were detected and classified. Ninety-five F1 generation hybrids of these materials, along with typical materials, were measured at the wax maturity stage. Test cross results demonstrated that the variation in dw1-dw3 genes in the breeding materials significantly influenced the plant height of hybrid offspring. The main male sterile lines in Chinese sorghum predominantly exhibited the "three-dwarf" type of Kafir and its improved lines, characterized by the genotype (Dw1-Dw2-dw3-dw4). On the other hand, restorer lines mainly showcased the improved "two-dwarf" (Dw1-Dw2-dw3-dw4) genotype of the Kaoliang/Caudatum subspecies, along with the "three-dwarf" type of some Kafir and its improved lines. The test materials predominantly contained dw3 genes, with relatively fewer dw1 genes in the restorer lines. The primary restorer materials lacked the dw2 gene, and dw2 significantly influenced plant type. The increased plant height in improved offspring of the same plant height type material was attributed to differences in gene types. Therefore, the enhancement of plant height in breeding materials should prioritize the use of different methods in conjunction with Dw1 and Dw2 classification. [ABSTRACT FROM AUTHOR]

Geographical background and dispersal ability may strongly influence assemblage dissimilarity; however, these aspects have generally been overlooked in previous large-scale beta diversity studies. Here, we examined whether the patterns and drivers of taxonomic beta diversity (TBD) and phylogenetic beta diversity (PBD) of breeding birds in China vary across (1) regions on both sides of the Hu Line, which demarcates China’s topographical, climatic, economic, and social patterns, and (2) species with different dispersal ability. TBD and PBD were calculated and partitioned into turnover and nestedness components using a moving window approach. Variables representing climate, habitat heterogeneity, and habitat quality were employed to evaluate the effects of environmental filtering. Spatial distance was considered to assess the impact of dispersal limitation. Variance partitioning analysis was applied to assess the relative roles of these variables. In general, the values of TBD and PBD were high in mountainous areas and were largely determined by environmental filtering. However, different dominant environmental filters on either side of the Hu Line led to divergent beta diversity patterns. Specifically, climate-driven species turnover and habitat heterogeneity-related species nestedness dominated the regions east and west of the line, respectively. Additionally, bird species with stronger dispersal ability were more susceptible to environmental filtering, resulting in more homogeneous assemblages. Our results indicated that regions with distinctive geographical backgrounds may present different ecological factors that lead to divergent assemblage dissimilarity patterns, and dispersal ability determines the response of assemblages to these ecological factors. Identifying a single universal explanation for the observed pattern without considering these aspects may lead to simplistic or incomplete conclusions. Consequently, a comprehensive understanding of large-scale beta diversity patterns and effective planning of conservation strategies necessitate the consideration of both geographical background and species dispersal ability. [ABSTRACT FROM AUTHOR]

With the ever-increasing number of large-span shield tunneling projects and the extended operational time, their distinctive internal component issues are becoming more pronounced and exhibiting unique characteristics. In order to reveal the cracking mechanism of concrete on the top of the middle partition wall, based on a large-span shield tunnel section of Nanjing Metro, the crack mode, distribution characteristics, and cracking process of concrete inside tunnel structure were studied by combined field investigation and extended finite element analysis. The results showed that: (1) there were 96 cracks of concrete on the top of the middle partition wall in the interval. Based on the propagation path, number, and shape of cracks, they could be divided into type I, II, III, Y, and Z, with type-Y and type-Z being subtypes of type-I. (2) The crack started at the opposite side of horizontal differential displacement of the flue plate. The development curves of the length and end width of type-I and type-II cracks showed the significant characteristics of three stages. The relationship between crack end width and length was nonlinear, showing that 250 and 225 mm, respectively, were the critical crack lengths growing with the rapid growth of the end width of type-I and type-II cracks. (3) In type-II cracks, the propagation curves of two cracks under the same working condition were consistent, and the spacing of plate joints greatly influenced the length and slope of each stage of the curve. For type-III cracks, the first crack propagation process was basically consistent with type-I and type-II cracks, and the propagation of the other two cracks had obvious brittle characteristics. [ABSTRACT FROM AUTHOR]

The PIK reactor at NRC "Kurchatov Institute"—PNPI is going to be equipped with a high-flux Ultra Cold Neutron (UCN) source for fundamental physics researches. The UCN source will use superfluid helium, which will make possible to achieve the density of UCN 2.2 × 103 cm–3, that has not yet been achieved anywhere in the world. The UCN source will be installed on the GEK-4 channel, which will make possible to obtain a low value of heat influx to cryogenic vessels from reactor radiation. The heat removal from the UCN source vessel will be implemented by using a heat exchanger. The calculated UCN density in the EDM spectrometer chamber at the PIK is going to be 200 cm–3, which is 20 times higher than the existing UCN densities in the world. For a new UCN source based on superfluid helium, an extensive research program has been developed in field of the physics of fundamental interactions, including the search for a nonzero neutron EDM, precision measurement of the neutron lifetime, and search for mirror dark matter. [ABSTRACT FROM AUTHOR]

In the case of loss-of-coolant accidents (LOCAs) at a tokamak fusion reactor (TFR) due to the outflow of water from the cooling system of the first wall/blanket or the divertor into the vacuum vessel, free hydrogen can be released as a result of high-temperature oxidation of beryllium and, to a lesser extent, tungsten and carbon that make up the surface of the vacuum vessel walls and divertor. In a number of accident scenarios, air from the containment rooms can also enter the vacuum vessel. At sufficiently high concentrations of hydrogen in the resulting steam–gas mixture in the vacuum vessel, a fire or explosion can occur, which threatens the structural integrity of the reactor. The most important phenomenon affecting the formation of the region with an increased hydrogen concentration is hydrogen stratification. Therefore, the safety analysis of a TFR, including the promising Russian TFR, should include numerical estimates of the possibility of stratification of hydrogen released during an accident. The article presents a physical model that makes it possible to estimate the characteristic parameters and location of the region with an increased hydrogen content in the LOCA accompanied by the entry of air into the vacuum vessel. [ABSTRACT FROM AUTHOR]

A nuclear fuel-breeding blanket of a hybrid fission-fusion reactor is considered in this work. The blanket design uses the tight layout of cylindrical heat-generating elements. The neutronic analysis of nuclear fuel breeding in a blanket is performed for source materials (metallic uranium and thorium, uranium dioxide, thorium dioxide, uranium nitride, and thorium nitride) in combination with various coolants—lead, sodium–potassium eutectic, carbon dioxide, water, steam–water mixture, and heavy water. The 239Pu breeding rate is about 6 kg/(m2 yr) at the neutron wall load of 0.4 MW/m2 or 15 kg/(MW yr) being normalized to the neutron power on the first wall in front of the fuel part of a blanket (for the most efficient combinations of initial material and coolant). The 233U breeding rate is about 3.5 kg/(m2 yr) at the neutron wall load of 0.4 MW/m2 or 9 kg/(MW yr) being normalized to the neutron power on the first wall in front of the fuel part of a blanket (for the most efficient combinations of initial material and coolant). [ABSTRACT FROM AUTHOR]

The tritium fuel cycle (FC) is one of the main systems of a fusion plant. Currently, active work is under way in Russia and worldwide to improve FC technologies in order to increase its efficiency and safety. Another area of work is demonstration and testing of technologies for large-scale systems of future fusion plants, which are characterized by large fuel flows and significant amounts of tritium in the systems. In order to plan work on the design and construction of fusion plants, it is necessary to analyze existing technologies and their readiness for use in FC. This article continues the analysis of the readiness of FC technologies of the DEMO-FNS facility in Russia started by the authors earlier. The Technology Readiness Level (TRL) methodology is used for the analysis, according to which technologies in the target application area correspond to different readiness levels from TRL 1 (basic principles observed and reported) to TRL 9 (actual system "flight proven" through successful mission operations). The article analyzes the technologies of tokamak pumping, tritium safety, and creation of materials for tritium handling. It is shown that in Russia vacuum technologies are poorly developed (TRL 2) and critically depend on the use of imported equipment. Methods for the analysis of tritium and its compounds, including technically complex ones, are actively used in Russia at various enterprises, but serial production of the necessary equipment exists for a small list of relatively simple methods, other methods are represented only by prototypes (often single samples), and the application of many analytical methods critically depends on the supply of foreign high-tech equipment. The technologies for creating multilevel protection and for capturing and processing of tritium waste are largely developed (TRL 6 and TRL 5), are applied in tritium laboratories and production facilities, and generally correspond to the world level. The level of readiness of materials for tritium handling (TRL 7) makes it possible to utilize existing technologies to produce equipment, components, and piping for FC systems outside the reactor vacuum vessel while operating at elevated temperatures. In the case of in-vessel components operating under severe neutron irradiation conditions, structural and functional materials should be appropriately tested (TRL 2–3). The level of readiness of the listed technologies is insufficient for application in the FC of the DEMO-FNS facility. It is necessary to increase the level of technology readiness within research and development programs, to create specialized stands for testing and demonstration of technologies, and to create experimental fusion plants for testing and integration of technologies. [ABSTRACT FROM AUTHOR]

Within the EUROfusion roadmap for the technological development of the European-DEMOnstration (EU-DEMO) reactor, a key point has been identified in the discontinuous operation (pulse-dwell-pulse) of the machine. Water Cooled Lithium Lead (WCLL) Breeding Blanket (BB) Primary Heat Transfer Systems (PHTSs) adopt technology and components commonly used in nuclear fission power plants, whose performances could be negatively affected by the above mentioned pulsation, as well as by low-load operation in the dwell phase. This makes mandatory a full assessment of the functional feasibility of such components through accurate design and validation. For this purpose, ENEA Experimental Engineering Division at Brasimone R.C. aims at realizing STEAM, a water operated facility forming part of the multipurpose experimental infrastructure Water cooled lithium lead -thermal-HYDRAulic (W-HYDRA), conceived to investigate the water technologies applied to the DEMO BB and Balance of Plant systems and components. The experimental validation has the two main objectives of reproducing the DEMO operational phases by means of steady-state and transient tests, as well as performing dedicated tests on the steam generator aiming at demonstrating its ability to perform as intended during the power phases of the machine. STEAM is mainly composed of primary and secondary water systems reproducing the thermodynamic conditions of the DEMO WCLL BB PHTS and power conversion system, respectively. The significance of the STEAM facility resides in its capacity to amass experimental data relevant for the advancement of fusion-related technologies. This capability is attributable to the comprehensive array of instruments with which the facility will be equipped and whose strategic location is described in this work. The operational phases of the STEAM facility at different power levels are presented, according to the requirements of the experiments. Furthermore, a preliminary analysis for the definition of the control strategy for the OTSG mock-up was performed. In particular, two different control strategies were identified and tested, both keeping the primary mass flow constant and regulating the feedwater mass flow to follow a temperature set-point in the primary loop. The obtained numerical results yielded preliminary feedback on the regulation capability of the DEMO steam generator mock-up during pulsed operation, showing that no relevant overtemperature jeopardized the facility integrity, thanks to the high system responsivity to rapid load variations. [ABSTRACT FROM AUTHOR]

The WCLL Breeding Blanket of DEMO and the Test Blanket Module (TBM) of ITER require accurate R&D activities, i.e., concept validation at a relevant scale and safety demonstrations. In view of this, the strategic objective of the Water Loop (WL) facility, belonging to the W-HYDRA experimental platform planned at C.R. Brasimone of ENEA, is twofold: to conduct R&D activities for the WCLL BB to validate design performances and to increase the technical maturity level for selection and validation phases, as well as to support the ITER WCLL Test Blanket System program. Basically, the Water Loop facility will have the capability to investigate the design features and performances of scaled-down or portions of breeding blanket components, as well as full-scale TBM mock-ups. It is a large-/medium-scale water coolant plant that will provide water coolant at high pressure and temperature. It is composed by single-phase primary (designed at 18.5 MPa and 350 °C) and secondary (designed at 2.5 MPa and 220 °C) systems thermally connected with a two-phase tertiary loop acting as an ultimate heat sink (designed at 6 bar and 80 °C). The primary loop has two main sources of power: an electrical heater up to about 1 MWe, installed in the cold side, downstream of the pump and upstream of the test section, and an electron beam gun acting as a heat flux generator. The WL has unique features and is designed as a multi-purpose facility capable of being coupled with the LIFUS5/Mod4 facility to study PbLi/water reaction at a large scale. This paper presents the status of the Water Loop facility, highlighting objectives, design features, and the analyses performed. [ABSTRACT FROM AUTHOR]

The Water-Cooled Lithium–Lead blanket concept is a candidate breeding blanket concept for the EU DEMO reactor and it is going to be tested as one of the Test Blanket Modules (TBM) inside the ITER reactor. A major safety issue for its design is the interaction between PbLi and water caused by a tube rupture in the breeding zone, the so-called in-box LOCA (Loss of Coolant Accident) scenario. This issue has been investigated in the framework of FP8 EUROfusion Project Horizon 2020 and is currently ongoing in FP9 EUROfusion Horizon Europe, defining a strategy for addressing and solving WCLL in-box LOCA. This paper discusses the efforts pursued in recent years to deal with this key safety issue, providing a general view of the approach, a timeline, research and development, and experimental activities. These are conducted to master dominant phenomena and processes relevant to safety aspects during the postulated accident, to enhance the predictive capability and reliability of selected numerical tools, and to validate and qualify models and codes and the procedures for their applications, including coupling and chains of codes. [ABSTRACT FROM AUTHOR]

The limited tritium resources available for the first fusion power plants (FPPs) make fuel self-sufficiency and tritium inventory minimization leading issues in FPP design. This work builds on the model proposed by Abdou et al (2020 Nucl. Fusion 61 013001), which analyzed the fuel cycle (FC) of a DEMOnstration nuclear FPP-class FPP with a time-dependent system-level model. Here, we use a modified version of their model to analyze the FC of an Affordable, Robust, Compact (ARC)-class tokamak and two versions of a Spherical Tokamak for Energy Production (STEP)-class tokamak. The ARC-class tokamak breeds tritium in a 2LiF + BeF2 liquid immersion blanket, while the STEP-class tokamak breeds tritium utilizing either a liquid-lithium blanket design or an encapsulated breeding blanket. A time-dependent system-level model is developed in Matlab Simulink® to simulate the evolution of tritium flows and tritium inventories in the FC. The main goals of this work are to assess tritium self-sufficiency of the ARC- and STEP-class designs and to determine quantitative design requirements that can be used to analyze the adequacy of a proposed FC system. These design requirements are aimed at achieving a low tritium inventory doubling time ( t d ) and a low start-up inventory ( I s t a r t u p ) while keeping the required tritium breeding ratio (TBR r ) as low as possible. We also consider how improvements in FC technology and POs affect TBR r and I s t a r t u p . The model results show that TBR r for ARC- and STEP-class FPPs should be achievable if the tritium burn efficiency (TBE) reaches 0.5%–1% (TBR r < 1.2). This assumes significant, but attainable, improvements over current abilities. However, the model results indicate that an FPP must achieve ambitious performance targets, including FPP availability > 70%, tritium processing time < 4 h, and the implementation of direct internal recycling (DIR). If future research yields major improvements to achievable TBE, it may be possible to achieve tritium self-sufficiency while operating at lower availability and without implementing DIR. [ABSTRACT FROM AUTHOR]

low-temperature, abiotic stress, molecular responses, plant biodesign, breeding, genome-editing, membrane lipids [ABSTRACT FROM AUTHOR]

Liquid metal lithium can cause severe corrosion on the surface of fusion reactor blankets and first-wall metal materials. Oxidized erbium ceramic has been widely studied as a candidate material for the self-cooling blanket system of tokamak fusion reactors. In this study, time-resolved picosecond laser-induced breakdown spectroscopy (ps-LIBS) was used to investigate the time evolution process of laser-induced plasma (LIP) of Er 2 O 3 samples in air at different pressures. The pressure-time windows with high signal-to-background ratio and high signal-to-noise ratio under LTE conditions were determined. The composition depth distribution of the Er 2 O 3 ceramic after static corrosion by lithium was analyzed. The number of laser pulses were linearly proportional to the laser ablation depth as measured by a three-dimensional profilometer. As the number of pulses increased, the relative intensities of the 610.353 nm and 812.645 nm characteristic lines of the corroding element Li gradually decreased, while the relative intensities of the 405.547 nm and 405.951 nm characteristic lines of the base element Er gradually increased. The laser pulse number at which the relative peak intensities of Er and Li reached a steady state showed a trend of first increasing and then decreasing with increasing pressure. In addition, the results of laser ablation depth under different environmental pressures indicated that the depth resolution of the analysis of anti-corrosion Er 2 O 3 ceramic materials can be controlled by the environmental gas pressure. [ABSTRACT FROM AUTHOR]

Water is a vital resource providing multiple services to many organisms, including birds. Eleonora's falcon is an iconic, long-distance migrant bird of the Palearctic region. While various aspects of its life history have been thoroughly studied, its dependence on water sources has been poorly documented. In this study, we examine for the first time the species' visitation patterns at a complex of small, natural ponds of karstic water on a Greek island and provide a detailed description of its bathing and drinking behaviour using visual observations and camera traps. Our results indicate that the species visits the ponds systematically from spring until autumn to bathe and drink. Water visitation patterns suggest communal behaviour, most probably benefitting from increased vigilance in greater numbers. In spring, male falcons prevail during water sessions and the reverse pattern is observed in autumn, whereas morph ratio remains stable, close to the expected 3:1 ratio. Temperature, affecting the falcons' foraging activity and/or their heat dissipation requirements, together with seasonal differences in labour division between sexes can explain a significant amount of the observed variability in water visitation patterns. Freshwater sources in most islets hosting breeding colonies are scarce, thus natural ponds in nearby larger islands are an important resource many falcons could rely on while at their breeding grounds. The identification and preservation of bathing and drinking spots where falcons gather in numbers across its breeding range is thus highly recommended. Considering the forecasted impact of climate change on karstic water we also encourage an in-depth analysis of the role of water in the adaptation of Eleonora's falcon to a life in insular environments experiencing global warming. Last but not least, further investigation of the species' communal behaviour regarding water use can also offer interesting insights in the species' natural history. [ABSTRACT FROM AUTHOR]

Two-phase lithium ceramic Li2TiO3-Li4SiO4 is considered as a tritium multiplier for use in the solid blanket of fusion reactors. To date, the most accurate understanding of the processes of tritium and helium production and release occurring in the breeder blanket materials under neutron irradiation can only be obtained from experiments in fission research reactors. At that, irradiations in vacuum give the possibility to register even very fast gas release processes (bursts) from the ceramics' voids and pores, although it reduces the thermal conductivity of the pebble bed. The purpose of this work was to simulate the heating of mono-sized pebble bed (1 mm in diameter) of two-phase lithium ceramic 25 mol%Li2TiO3+75 mol%Li4SiO4 in an ampoule device during neutron irradiation at the WWR-K research reactor under vacuum conditions, and to determine experimental parameters in order to prevent heating of the lithium ceramics up to the Li4SiO4-Li2SiO3 phase transition temperatures (>900 °C). For the first time, it was obtained that the effective thermal conductivity of a 1 mm mono-sized pebble bed of 25 mol%Li2TiO3+75 mol%Li4SiO4 significantly decreases (four times) when it is irradiated with neutrons in a vacuum (at a helium pressure of approximately 10 Pa), compared to a similar calculation at 100 kPa of helium (when the He sweep is used). It was concluded that it is difficult to evaluate the maximal temperature of the ceramics in the capsule by measuring the temperature of its outer metal wall (according to thermocouple readings) without using the results of thermophysical calculations for each type of ceramic, taking into account its quantity, specific heat release and pebble size(s). To control the temperature of the ceramics during an irradiation experiment in a vacuum, an in-capsule thermocouple should be used, placed in the center of the pebble bed. Measuring the temperature of the pebble bed based on the capsule wall temperature can lead to overheating of the ceramics and phase changes. [ABSTRACT FROM AUTHOR]

Numerical simulations have been carried out in support of an experimental campaign conducted in the MEKKA laboratory at KIT. The aim is investigating liquid metal heat transfer with an imposed magnetic field in a model geometry relevant for the study of water cooled lead lithium blankets for fusion reactors. In the breeding zone of this blanket concept, cooling pipes are immersed in the liquid metal in which convective motion occurs due to significant temperature gradients. The test-section features a rectangular box containing two horizontal cylinders kept at constant differential temperatures in order to establish a temperature gradient that drives the buoyant flow. A magnetic field B is applied parallel to gravity. The magneto-convective flow, which results from the presence of electromagnetic forces and temperature gradients in the fluid, is relatively complex, since the liquid metal has to move around the cylinders. For weak magnetic fields, a convective recirculation is fed by a jet-like flow formed by the boundary layers that detach from the pipe walls and recombine behind the obstacles. For sufficiently strong B , the thermal field resembles that of a conductive regime with vertical isotherms and the fluid is nearly stagnant in most of the cavity except in layers parallel to magnetic field lines and tangent to the cylinders. The rate of convective heat transfer decreases with an increase of the magnetic field. Numerical simulations complement experimental results and give insight into phenomena that cannot be directly analyzed by means of measured quantities. [ABSTRACT FROM AUTHOR]

An idealized design of a silicon betavoltaic battery with a tritium source is considered, in which a thin layer of tritiated silicon is sandwiched between two intrinsic silicon slabs of equal width, and the excess charge carriers are collected by thin interdigitated n+ and p+ electrodes. The opposite sides of the device are covered with a reflecting coating to trap the photons produced in radiative recombination events. Due to photon recycling, radiative recombination is almost ineffective, so the Auger mechanism dominates. An analytical expression for the current–voltage curve is obtained, from which the main characteristics of the cell, namely, the open-circuit voltage, the fill factor, and the betaconversion efficiency, are found. The analytical results are shown to agree with the numerical ones with better than 0.1% accuracy. The optimal half-thickness of this device is found to be around 1.5 μm. The maximal efficiency increases logarithmically with the surface activity of the beta-source and has the representative value of 12.07% at 0.1 mCi/cm2 and 14.13% at 10 mCi/cm2. [ABSTRACT FROM AUTHOR]

A large amount of Li‐containing ceramic breeder pebbles is packed in the solid breeding blanket of a nuclear fusion reactor. Several pebble fabrication technologies have been proposed in previous studies, including wet process, emulsion method, extrusion spheronization, additive manufacturing, and melt process. However, a simple, energy‐effective, and scalable fabrication technology remains to be developed for the automated mass production and reprocessing of used radioactive pebbles post‐operation. Selective laser melting potentially enables the quick and automated fabrication of breeder pebbles. Herein, we employ a high‐power density pulse laser to produce ceramic breeder pebbles. A pulsed YAG laser was irradiated over a lithium metatitanate (Li2TiO3) powder bed in air, and the corresponding temperature was monitored using fiber‐type infrared pyrometers. Spherical Li2TiO3 pebbles were successfully fabricated in a single step with an average diameter of 0.78 ± 0.13 μm and the sintering density of 87.4% ± 5.6% (input power: 7.9 J/pulse). The irradiated Li2TiO3 powder melted and turned spherical under surface tension and rapidly solidified, resulting in uniaxial fine grains and a decrease in the degree of long‐range cation ordering. [ABSTRACT FROM AUTHOR]

Tritium levels in the groundwater of arid regions are very low; in most cases, these low tritium levels cannot be detected using a conventional liquid scintillation counter (LSC). To measure the tritium activity concentration, low-level tritium in groundwater needs to be enriched by a known factor so that the scintillation counter can detect it. An electrolysis process with electrolytic cells was designed and fabricated in our laboratory following the International Atomic Energy Agency (IAEA) instructions. Nine spiked samples with a known quantity of tritium were enriched, and the tritium activity concentration was measured using the scintillation counter. The enriched water exhibits a comparable level of spiked samples, albeit with some degree of uncertainty. A correlation was drawn among the tritium activity, enrichment factor, and the required time for the electrolysis procedure. This study confirmed that an enrichment process of approximately ten- to fortyfold of the initial concentration of the tritium could be achieved using the electrolysis process with the fabricated electrolytic cells. The simple design and fabrication of the electrolysis process by controlling various parameters make it affordable to measure low-level tritium using a conventional LSC. Various statistical analyses confirmed the accuracy and precision of the data obtained by the electrolysis process. This enrichment technique would prove valuable in regions where tritium levels in groundwater are extremely low, making them challenging to detect using conventional liquid scintillation counter. [ABSTRACT FROM AUTHOR]