Search Results (285)

Groundwater quantification is essential for sustainable water resources management, yet it is often hampered by limited data availability and difficulties in measuring spring discharges. This study investigates three carbonate aquifers in Central Italy’s Abruzzo region: the Genzana–Greco, Morrone, and Marsicano mountains. The aim is to resolve uncertainties in spring attribution, and groundwater flow patterns using isotopic analyses combined with field surveys. The Genzana–Greco aquifer was examined to clarify the sources of the Acquachiara spring and the previously unreported Germina spring, assessing whether recharge occurs locally or from the carbonate massif. In this case, the results indicate that the Germina, together with a similar known spring of Capolaia, share a common recharge sector, while the Acquachiara spring is mainly fed by higher-elevation carbonate areas, excluding significant contributions from local alluvial deposits. In the Morrone mountain aquifer, discharge gains along the Pescara River through the Gole di Popoli were quantified, and spring isotopic compositions were compared to the main basal spring Giardino to better define groundwater contributions. In this case study, the stable isotopes and tritium data confirm recharge from the central–southern massif and support the identification of basal springs and Pescara River gains as primary discharge points, with minimal influence from surface water. For the Marsicano mountain aquifer, the role of Lake Scanno in feeding the Villalago springs was investigated through isotopic analysis of inflows, downstream springs, and basal aquifer discharge points to constrain the hydrogeological water budget. The results highlight Lake Scanno’s role in the recharge of Villalago springs and delineate the Cavuto group as a major discharge system receiving inputs from central and northern sectors of the massif. Overall, the integration of isotopic tracers with hydrological measurements allowed a more precise characterization of aquifer recharge areas, Mean Residence Times, and groundwater flow paths, improving the understanding of regional water resources in a complex carbonate setting. Full article

The breeding blanket is a key component of tokamaks, primarily responsible for extracting heat from fusion reactions and for tritium breeding, which is essential to ensure a fusion reactor’s fuel self-sufficiency. Recent technological advancements have led to the development of Dual-Cooled Lead–Lithium (DCLL) breeding blankets, which employ a liquid metal (specifically a Lead–Lithium eutectic alloy) as a heat transfer medium and tritium breeder, while helium gas is used to cool the structural components of the reactor. The interaction between the moving electrically conducting fluid and the strong magnetic field in the tokamak environment leads to magnetohydrodynamic (MHD) effects. The latter are characterized by the induction of eddy currents within the fluid and resulting Lorentz forces generated by their interaction with the magnetic field, which cause additional pressure losses and reduce heat transfer efficiency. This work investigates the pressure drop experienced by a Lead–Lithium flow within a rectangular section conduit under the action of an external, uniform magnetic field of different intensities. An analytical model was developed to estimate the total MHD-induced pressure losses along the channel for different values of the external magnetic field intensity and then benchmarked against relative computational fluid dynamics (CFD) simulations carried out using COMSOL Multiphysics. This comparison allowed the validation of the analytical predictions as well as a better understanding of the influence of the applied magnetic field intensity on the overall pressure drop. Therefore, the aim of the analytical model is to provide analytical tools for reasonably accurate estimations of MHD pressure losses suitable for future preliminary design purposes. Full article

At the end of its last experimental campaign, in December 2023, the Joint European Torus (JET) became available for testing a compact and lightweight Laser-Induced Breakdown Spectroscopy (LIBS) system to be mounted on its robotic arm. The purpose of the test was the in situ chemical characterization of its internal walls and plasma-facing components (PFCs). Among the areas measured, special attention was devoted to the PFCs of the divertor, as this area is most affected by the re-deposition of material eroded from the first wall and unburned nuclear fuel (deuterium and tritium). In this article, we present the results of the LIBS characterization of a PFC of the High Field Gap Closure (HFGC), highly subjected to these phenomena. The in-depth distribution of several ITER-relevant chemical species is discussed through in-depth and correlation analyses, and the interpretation of the results is explained in terms of erosion and re-deposition of materials from the first wall. The study allowed us to estimate the thickness of the ablated layers by each laser shot, which is on the order of a few tens of nanometers, and to outline a mapping of the thickness of the re-deposited material. Full article

Plasma Enhancement Gases (PEGs) are a set of gaseous elements studied for converting plasma thermal energy and mitigating the heat load on the plasma-facing components of a tokamak fusion power plant. In particular, PEG separation is part of the Plasma Exhaust Processing System of EU-DEMO. This work addresses issues related to the purification of Deuterium-Tritium fusion fuel, introducing ceramic membranes having a low specific area to process and purify unburned streams throughout the fuel cycle. A commercial microporous mono-channel α-Alumina membrane was considered for the evaluation of its efficacy in separating binary mixtures of H₂ with a PEG (Ar and N₂), D₂, or He. Several tests were carried out, feeding equimolar streams of H₂-Ar, H₂-N₂, D₂-Ar, and He-Ar, and the separation factor (SF) of the aforementioned binary mixtures was experimentally assessed. Finally, based on the results from the experimental campaign, the separation factors of several gas mixtures that had not been experimentally investigated were theoretically calculated and proposed. Full article

Optical fibres are considered for applications in various nuclear environments in the presence of radiation exposure. Under irradiation, the properties of the optical fibres are modified. In the present paper we investigate the influence of gamma radiation on the magneto-optical properties of the Corning SMF-28e optical fibre. The stability of the Verdet constant is an important requirement for performing current measurements under radiation, for example, in magnetic fusion installations during nuclear (deuterium–tritium) plasma operation, where radiation at MGy dose levels can be accumulated. Our results demonstrate that radiation-induced changes in the Verdet constant are within its measurement accuracy (0.56%) for gamma radiation doses up to 770 kGy. Full article

The geothermal system in the Jiaodong Peninsula is situated within a continent–ocean transition zone, where complex interactions among meteoric water, geothermal fluids, and seawater produce diverse hydrogeochemical and isotopic signatures, complicating geothermal resource assessment and sustainable development. To constrain recharge sources and seawater mixing mechanisms, geothermal water samples were systematically collected from 15 geothermal fields and analyzed using integrated hydrogeochemical methods and multi-isotope tracers (δD–δ¹⁸O, δ³⁴S-SO₄²⁻, ⁸⁷Sr/⁸⁶Sr, and ³H). The results show that geothermal waters are predominantly recharged by meteoric precipitation, with δD–δ¹⁸O values distributed along the meteoric water line, while low d-excess values indicate prolonged circulation and significant water–rock interaction. Seawater mixing exhibits marked spatial heterogeneity: only 5 of the 15 fields show detectable marine influence. Chloride-based calculations suggest apparent seawater fractions of up to ~34% in BQ and <4% in DY, whereas the remaining fields show negligible mixing. Sulfur and strontium isotopes indicate contributions from external sulfate sources and continued water–rock interaction rather than simple mixing with modern seawater. Low tritium contents further imply involvement of deeply circulated paleo-seawater. The system is therefore interpreted as a fault-controlled seawater-mixing geothermal system, providing insights into coastal geothermal evolution and resource evaluation. Full article

This study explores the hydrochemical and thermal characteristics of a fault-controlled geothermal field within the Northern Qinghai Lake Coalfield Area on the northeastern Qinghai–Tibetan Plateau (QTP). This research integrates hydrochemical analyses, isotopic tracers, and the regional geological framework to define hydrochemical signatures, identify recharge sources and flow paths, assess cold–hot water mixing, estimate reservoir temperatures, determine circulation depths and residence times, and explain the geothermal system’s formation. Systematic sampling included geothermal waters, cold springs, and surface waters, followed by laboratory analysis of major ions, stable isotopes (δ²H, δ¹⁸O), radiocarbon (¹⁴C), and tritium (³H). The geothermal water is categorized as a low-temperature, weakly acidic to near-neutral HCO₃-Ca•Mg type, exhibiting temperatures from 35.6 to 46.2 °C. Isotopic analyses indicate that cold spring and river waters align with the local meteoric water line, while geothermal waters display distinct isotopic signatures, suggesting deeper circulation. A silica–enthalpy mixing model reveals substantial cold-water mixing during upwelling, with mixing ratios between 74.5% and 85.6%. The corrected recharge elevation is estimated to be 4378–4456 amsl, implying a primary recharge zone in the branch of the Qilian mountains—the middle section of Datong Mountain to the northeast. Geothermometry, employing quartz and chalcedony temperature scales and accounting for mixing, estimates reservoir temperatures of 150–202 °C. The calculated circulation depth spans 3211–4291 amsl. Low tritium levels and carbon dating suggest a deep-cycling system predating 1952, characterized by deeply circulating “ancient water”. The geothermal system’s development is associated with regional tectonics, fault systems, and the Kesuer Formation (J_xk) acting as the reservoir. This study provides a scientific foundation for the development and sustainable use of geothermal resources in the northern Qinghai Lake region and offers insights applicable to comparable fault-controlled geothermal systems across the QTP. Full article

Ice cores retrieved from the Third Pole provide invaluable information about past and present environmental changes. Here we present, for the first time, a continuous tritium and plutonium isotope profile of the Puruogangri ice field, Tibetan Plateau, China, for the last 70 years. The age-depth profile has been composed by different time anchors such as the onset of thermonuclear weapon tests, the so-called bomb peak of tritium, the Chernobyl event, and the time of ice coring. The accumulation rate of ice calculated from the age-depth relation shows a decrease after 1963. It was 57, 15, and 22 cm/year in the periods of 1954–1963, 1963–1986, and 1986–2023, respectively. The concentrations of plutonium isotopes (²³⁹Pu: up to 2.7 fg/g) are slightly lower than those of the Belukha ice core, Siberian Altai, Russia, and almost the same as the Miaoergou glacier, eastern Tien Shan, China. Contrary to this latter ice core profile, the Puruogangri plutonium profile reflects that the Chinese weapon test started in 1966. This is confirmed by the tritium time series as well. ²⁴⁰Pu/²³⁹Pu atomic ratios vary between 0.14 and 0.23, with an average of 0.177 ± 0.024. The overall obtained local fallout of ²³⁹Pu and ²⁴⁰Pu is 13.2 and 9.0 Bq/m² (4.0 and 1.1 ng/m²), respectively. Full article

Temperature Swing Absorption (TSA) is the primary candidate for the Isotope Rebalancing and Protium Removal (IRPR) system within the envisioned EU-DEMO fusion reactor fuel cycle. TSA separates a mixed hydrogen isotope stream into two product streams using a semi-continuous process. One stream, enriched in heavy isotopes, is used to re-establish the required deuterium-to-tritium fuel ratio. The second, enriched in protium, is stripped off from the fuel cycle to counteract the protium build-up. Separation is achieved by cycling an isotope mixture between two columns filled with metallic absorption materials that have opposite isotope effects of metal hydride formation. The selection of these materials, the operation parameters and the column geometry allow for adjusting the resulting enrichments. To identify suitable operation parameters, a TSA process model is developed which depicts the process dynamics and interactions between the columns. A modified process operation mode is introduced, which enables higher system throughputs and non-cryogenic operation, i.e., operational temperatures between 0 to 130 °C, while reducing the tritium inventory due to shorter cycling times by reduced amplitudes of the temperature swings. Finally, simulations of a TSA system at relevant scale confirm the suitability of TSA technology for the separation task of the EU-DEMO IRPR system. Full article

Northwestern Jiangxi Province is rich in metasilicic acid (as H₂SiO₃) mineral water resources. Investigating their hydrogeochemical characteristics and formation mechanism is crucial for the rational utilization of water resources and the sustainable development of the local mineral water industry. Taking the Taoping water source area in northwestern Jiangxi as a case study, 11 sets of groundwater and surface water samples were systematically collected. By comprehensively applying mathematical statistics, ionic ratios, and isotopic analyses, the hydrogeochemical characteristics and formation processes of metasilicic acid-type mineral water were examined. The results indicate that: (1) The mineral waters in the area are weakly alkaline and belong to the metasilicic acid type, with concentrations ranging from 22.0 to 67.0 mg/L, of which 75% exceed 30 mg/L. (2) The primary hydrochemical types are HCO₃⁻–Ca·Na, HCO₃⁻–Ca·Mg, and HCO₃⁻–Ca. Analysis of stable isotopes (δ¹⁸O and δ²H) and tritium (³H) indicates that metasilicic acid mineral water is primarily recharged by atmospheric precipitation, with an apparent groundwater age of approximately 60 years. (3) The enrichment of metasilicic acid primarily results from the weathering and leaching of silicate minerals, coupled with cation exchange. K⁺ and Na⁺ are mainly derived from silicate minerals such as feldspars and halite, whereas Ca²⁺ and Mg²⁺ originate primarily from carbonate minerals like calcite and dolomite. During recharge, atmospheric precipitation infiltrates the aquifer, dissolving aluminosilicate and siliceous minerals in the surrounding rocks, thereby releasing metasilicic acid into the groundwater and ultimately forming the metasilicic acid-type mineral water. Full article

Tritium (³H) is a low-energy β emitter commonly found in environmental water samples, and its routine monitoring requires highly sensitive techniques capable of achieving low detection limits. Liquid scintillation counting (LSC) is the standard method for low-level ³H analysis; however, quenching significantly affects detection efficiency and minimum detectable activity (MDA), and systematic evaluations across different quench levels and measurement approaches remain limited. This study evaluates quench-related uncertainties in low-level ³H measurement using two ultra-low background liquid scintillation counters, Quantulus 1220 and GCT 6220. High- and low-quench conditions were created by varying sample-to-cocktail ratios, and performance was assessed through detection efficiency, minimum detectable activity (MDA), and stability. Under the relative measurement method with limited quench variation, GCT 6220 achieved higher efficiency, lower background, and lower detection limits. Under the internal standard method with broader quench spans, Quantulus 1220 produced smoother efficiency–quench curves and more stable results. Thus, GCT 6220 is advantageous for sensitivity-demanding scenarios, while Quantulus 1220 is better suited for quench-correction applications. Full article

Specifically engineered heavy liquid metals are proposed as candidate coolants and tritium breeders for advanced nuclear applications. Understanding the wetting behaviours of these liquids on relevant substrate configurations is crucial to tackle the challenges associated with corrosion protection and flow diagnostics development. However, detailed investigations are scarce in the literature. In this experimental study, an apparatus is designed to measure contact angles of different liquid metals over a mirror-polished horizontal SS-304 substrate. This paper presents design aspects of the developed test facility, as well as initial results obtained using direct imaging and the Low-Bond Axisymmetric Drop Shape Analysis algorithm-based image processing technique. Methodological validation is achieved through surrogate liquids/liquid metals (H₂O, Hg, Ga, GaInSn), prior to taking measurements from molten lead (Pb) droplets at 425 °C. Estimated contact angles obtained using the two techniques lie within ±10% deviation. Towards the end, the paper lays out plans for future upgrades for studies of wetting behaviours of molten Pb/Pb alloys on substrates with relevant surface properties, including bare P-91 and reduced-activation ferritic–martensitic steels, along with Al₂O₃/Er₂O₃-coated versions of these materials, to generate a database for Gen-IV fission reactors and fusion power plants. Full article

Groundwater recharge sources and residence times in the Sulaimani–Warmawa Sub-basin, located in the Kurdistan Region of Iraq, were assessed through an integrated hydrogeological, hydrochemical, and isotopic investigation. The study area, located around Sulaimani City, is characterized by a semi-arid climate with precipitation predominantly occurring during winter and early spring. Hydrochemical results indicate groundwater types ranging from Ca–HCO₃ to Mg–Ca–HCO₃, accompanied by a progressive increase in electrical conductivity along the regional flow path. Stable isotope signatures (δ²H and δ¹⁸O) show that groundwater is primarily recharged by winter precipitation derived from both Eastern Mediterranean and Persian Gulf air masses. Two groundwater groups were identified based on isotopic composition and tritium content: recently recharged groundwater and older groundwater, represented by two samples. Tritium values ranging from 0.8 to 4.9 TU correspond to minimum residence times from less than 10 years to approximately 40 years. Higher tritium concentrations near recharge zones reflect recent infiltration, whereas lower values indicate older groundwater with limited modern recharge. The piston flow model provided the best fit for tritium data, suggesting limited mixing and relatively rapid subsurface flow. Samples with higher salinity likely reflect reduced flushing in low-permeability zones, resulting in elevated dissolved solids. Hydraulic-data-based estimated groundwater flow velocities yielded lower values compared to tritium-based estimates, implying preferential flow in karstified formations. The relatively short groundwater residence times mean there is high vulnerability to contamination, emphasizing the need for careful land-use planning and groundwater protection strategies. Full article

Groundwater and water supply systems are increasingly vulnerable to contamination, yet most assessments consider either hydrogeological or infrastructure risks. This study introduces the Total Integrated Network (TIN) approach, a framework designed to evaluate vulnerability comprehensively from source to tap. Field investigations were conducted in Varaždin County, Croatia, focusing on the Belski Dol spring, Briška reservoir, and PS Filipići. Hydrochemical analyses, stable isotope of water (δ¹⁸O, δ²H), tritium, noble gases, and radon concentrations were monitored and combined with system-level assessments. Results show that the Belski Dol spring exhibits high stability and low vulnerability, with a TIN index of approximately 25%, supported by long groundwater residence times and consistent water quality. PS Filipići displayed moderate vulnerability (35%), while the Briška reservoir showed the highest index (53%), linked to elevated radon and nitrate concentrations and infrastructure-related risks. These findings indicate that natural hydrogeological protection alone cannot ensure safe drinking water. The TIN approach highlights the importance of integrating aquifer conditions with distribution system performance to identify critical control points and prioritize interventions. This integrated methodology offers a more realistic basis for water safety management, supporting proactive measures to safeguard supply resilience and public health. Full article

Concrete-lined river channels are generally assumed to prevent groundwater exchange, functioning as inert conduits that isolate surface flow. Along the Upper Los Angeles River of Southern California, United States, however, field observations show that during dry summer months, groundwater seepage contributes nearly half of the dry-weather flow to a 9.5-km concrete-lined reach above Sepulveda Basin. This baseflow substantially modifies river chemistry, diluting some solutes while enriching others. To characterize these interactions, hydrochemical sampling was conducted in summer 2022, with additional selenium and tritium analyses from 2024 to 2025, covering tributaries, river sites, groundwater seeps, wastewater discharges, and tap water. Analyses included major ions, nutrients, selenium, and tritium. Upstream tributaries were highly saline (TDS ≈ 1670 mg/L; sulfate up to 980 mg/L; chloride ≈ 280 mg/L), whereas groundwater was moderately saline (TDS 990 to 1765 mg/L) but contained elevated nitrate-nitrogen (5.8 to 12.9 mg/L) and selenium (4.5–44.0 µg/L). Mixing analysis indicated that approximately 45% of the river’s dry-weather flow (~70.5 L/s) originated from groundwater, increasing riverine selenium above the 5 µg/L aquatic-life criterion. Downstream, where the concrete lining ends, wastewater inflows from the Donald C. Tillman Water Reclamation Plant reduced salinity but introduced additional nitrate-nitrogen. The results reveal a three-part sequence; saline tributary inputs at the headwaters, groundwater-driven nitrate and selenium enrichment within the lined reach, and effluent dilution downstream. These findings demonstrate that even concrete-lined channels can host active groundwater–surface water exchange, highlighting the need to incorporate such interactions in urban river management and channel design. Full article