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Non-evaporable getters (NEGs) are metallic compounds of the IV group, particularly titanium and/or zirconium-based alloys and are usually used as pumps in vacuum technologies since they are able to sorb, by chemical reactions, most of the active gas molecules, with particular efficacy towards hydrogen isotopes. This work suggests an alternative application of these materials to fusion nuclear reactors, where there is the need to recover small amount of tritium from the large helium flow rate composing the primary coolant loop. Starting from the tritium mass balance inside the primary coolant loop, the amount of coolant to be routed inside the coolant purification system (CPS) is identified. Then a feasibility study, based on the bulk getter theory, is presented by considering three different commercial alloys, named ST707, ST101 and ZAO. The results provide the mass, the area and the regeneration parameters of the three different alloys necessary to fulfill the requirements of the CPS unit. By comparing the features of the three alloys, the ZAO material appears the most promising for the proposed application because it requires the lower amount of material and a lower number of regeneration cycles.

This paper presents the results of a study of the distribution of the radionuclide tritium ( 3 H) and stable isotopes of hydrogen and oxygen in the Shagan River. The Shagan River flows through the territory of the ‘Balapan’ test site and is the longest watercourse on the territory of the former Semipalatinsk Test Site (STS), and is also a left-bank tributary of the Irtysh River. The isotope hydrology method ( 2 H and 18 O) was used to determine the conditions for the formation of tritium-contaminated waters in the Shagan River. The study revealed certain sections of the river, especially at distances of 5, 10 and 14 km from the source, where elevated concentrations of tritium and stable isotopes indicated a significant influx of groundwater. A combined analysis of the isotopic composition and mineralization helped to assess the role of evaporation and identify hyporheic zones that contribute to the redistribution of radionuclides. At the confluence of the Shagan and Irtysh rivers, tritium activity does not exceed the intervention level of 7600 Bq/l recommended by the World Health Organization and the International Atomic Energy Agency for drinking water.

Significance Diffusion-weighted MRI (DWI) tractography is widely used to map structural connections of the human brain in vivo and has been adopted by large-scale initiatives such as the human connectome project. Our results indicate that, even with high-quality data, DWI tractography alone is unlikely to provide an anatomically accurate map of the brain connectome. It is crucial to complement tractography results with a combination of histological or neurophysiological methods to map structural connectivity accurately. Our findings, however, do not diminish the importance of diffusion MRI as a noninvasive tool that offers important quantitative measures related to brain tissue microstructure and white matter architecture. Tractography based on diffusion-weighted MRI (DWI) is widely used for mapping the structural connections of the human brain. Its accuracy is known to be limited by technical factors affecting in vivo data acquisition, such as noise, artifacts, and data undersampling resulting from scan time constraints. It generally is assumed that improvements in data quality and implementation of sophisticated tractography methods will lead to increasingly accurate maps of human anatomical connections. However, assessing the anatomical accuracy of DWI tractography is difficult because of the lack of independent knowledge of the true anatomical connections in humans. Here we investigate the future prospects of DWI-based connectional imaging by applying advanced tractography methods to an ex vivo DWI dataset of the macaque brain. The results of different tractography methods were compared with maps of known axonal projections from previous tracer studies in the macaque. Despite the exceptional quality of the DWI data, none of the methods demonstrated high anatomical accuracy. The methods that showed the highest sensitivity showed the lowest specificity, and vice versa. Additionally, anatomical accuracy was highly dependent upon parameters of the tractography algorithm, with different optimal values for mapping different pathways. These results suggest that there is an inherent limitation in determining long-range anatomical projections based on voxel-averaged estimates of local fiber orientation obtained from DWI data that is unlikely to be overcome by improvements in data acquisition and analysis alone.

This paper reports the activity concentrations of 137 Cs, 90 Sr, 239+240 Pu, 241 Am, and 3 Н in the form of tritiated water (НТО) and organically bound tritium (ОBТ) in the tissues and organs of roe deer ( Capreolus pygargus Pal., 1771) that inhabit the ‘Degelen’ test location of the Semipalatinsk Test Site. Tissues and organs were sampled from six deer by killing. The activity concentrations of specific radionuclides in the samples were measured using γ-, α-, and β-spectrometry. The radionuclide activity concentrations in the tissues and organs showed considerable variation, for example, 0.6–170 Bq kg -1 for 137 Cs and 0.3–2.8×10 3 Bq kg -1 for 90 Sr. The activity concentrations of radionuclides in animal muscular tissue did not exceed permissible values for the meat of wild animals. The tissues and organs in the roe deer were arranged as follows in descending order of their ability to accumulate 137 Cs and 90 Sr: for 137 Cs, muscular tissue–kidneys–lungs–spleen–heart–liver–bone tissue; for 90 Sr, bone tissue–liver–lungs–muscular tissue–spleen–heart–kidneys. The activity concentrations of 241 Am and 239+240 Pu did not exceed the minimum detectable activity. Therefore, no quantitative values could be determined for 241 Am, and the 239+240 Pu activity concentration could be derived for only one sample: 0.5±0.1 Bq kg -1 (liver). The distribution pattern of these radionuclides in the tissues and organs of the roe deer could not be determined because of insufficient data. The HTO volumetric activity in the tissues and organs of the examined animals ranged from 2.6×10 −2 to 77 kBq l -1 ; activity concentration of OBT, 3.0×10 −2 to 16 kBq kg -1 ; and OBT-to-HTO ratios, 2.0×10 −3 to 5.3×10 2 . This ratio can serve as an indicator of how long the examined animals stay in radioactively contaminated ecosystems. Within the ‘Degelen’ site, the activity concentrations of 90 Sr and tritium, in the form of HTO and OBT, are expected to be high in the bone tissues, soft tissues, and organs, respectively.

This article presents research findings on tritium ( 3 H) in plants at the Semipalatinsk Test Site (STS), including the perimeter of the ‘Degelen’ site, the riverside zone of the Shagan River, and a conditionally ‘background’ area—the southeastern part of the STS (SEP). The 3 H content in plants was determined in tritiated free water (TFWT) and organically bound 3 H (OBT). Plant samples were measured using an ultra-low-level liquid scintillation spectrometer. Maximum 3 H concentrations in plants were detected at the ‘Degelen’ site (TFWT up to 51 ± 5 kBq/kg, ОBТ up to 15 ± 1 kBq/kg) and Shagan River (TFWT up to 39 ± 4 kBq/kg, ОBТ up to 13 ± 1 kBq/kg). The presence of 3 H was recorded not only at underground nuclear sites but also in the conditionally ‘background’ area (TFWT up to 0.18 ± 0.02 kBq/kg, ОBТ up to 0.088 ± 0.028 kBq/kg). Research suggests that water plays a key role in 3 H migration processes in the natural system of interest. The OBT/TFWT values for the study area varied on average from 0.3 to 0.7. The dose rate of internal irradiation of the studied plants varied from 6.3 × 10 −6 (SEP) to 1.2 × 10 −2 µGy/day (at the boundary of the ‘Degelen’ site), which is significantly lower than the safe exposure level for biota.

Coat proteins (CP) of the potato virus A virions (PVA) contain partially disordered N-terminal domains, which are necessary for performing vital functions of the virus. Comparative analysis of the structures of coat proteins (CPs) in the intact PVA virions and in the virus particles lacking N-terminal 32 amino acids (PVAΔ32) was carried out in this work based on the tritium planigraphy data. Using atomic-resolution structure of the potato virus Y potyvirus (PVY) protein, which is a homolog of the CP PVA, the available CP surfaces in the PVY virion were calculated and the areas of intersubunit/interhelix contacts were determined. For this purpose, the approach of Lee and Richards [Lee, B., and Richards, F. M. (1971) J. Mol. Biol., 55, 379-400] was used. Comparison of incorporation profiles of the tritium label in the intact and trypsin-degraded PVA∆32 revealed position of the ΔN-peptide shielding the surface domain (a.a. 66-73, 141-146) and the interhelix zone (a.a. 161-175) of the PVA CP. Presence of the channels/cavities was found in the virion, which turned out to be partially permeable to tritium atoms. Upon removal of the ∆N-peptide, decrease in the label incorporation within the virion (a.a. 184-200) was also observed, indicating possible structural transition leading to the virion compactization. Based on the obtained data, we can conclude that part of the surface ∆N-peptide is inserted between the coils of the virion helix thus increasing the helix pitch and providing greater flexibility of the virion, which is important for intercellular transport of the viruses in the plants.

During the period from 2019 to 2021, a series of experiments were carried out to study the uptake of tritium by crops in an area heavily contaminated with atmospheric tritium oxide (HTO), at the former Semipalatinsk test site in Kazakhstan. A quantitative assessment is given of the tritium uptake by typical crops (lettuce, tomatoes, peppers and beans) cultivated all over Kazakhstan in the case of a short-term tritium oxide vapor exposure. The plant samples were collected during and after exposure and analyzed for the tritium concentration in two chemical forms: tissue-free water tritium (TFWT) and organically bound tritium (OBT). During the entire series of experiments, the tritium concentration in free water from leaves and ambient air was of the same order of magnitude. The tissue water tritium concentrations of stems and edible parts was 1 to 2 orders of magnitude lower than in the surrounding air. The average value of the TFWT/HTO atm ratio in the leaves and the edible part was (0.73±0.2) and (0.04±0.002), respectively. The organically-bound tritium concentration is 1–2 orders of magnitude lower than the tissue water tritium and ambient air concentrations. Under aerial tritium oxide uptake, the distribution of tritium in non-leafy crops was as follows: leaf–stem–fruit (in decreasing order). After exposure, a non-significant amount of tritium is firmly retained in plants for a long time. The tissue water tritium concentrations correlate closely with atmospheric tritium oxid ( r = 0.76), correlate weakly with temperature ( r = 0.43) and relative humidity ( r = -0.43), and correlate moderately with solar radiation intensity ( r = 0.56). There was no reliable correlation between the concentration of tritium in organic matter and in ambient air. The concentration of tritium in the free water of leaves is closely correlated with the concentration in the free water of the stems ( r = 0.95) and fruits ( r = 0.78). The organically-bound tritium concentration in leaves is closely correlated with the organically-bound tritium concentration in stems ( r = 0.99) and fruits ( r = 98). The results of the study should be considered when evaluating the impact of tritium oxide emissions on the population living near nuclear power.

Understanding the hydrogeological regime and identifying the sources of salinity in mine pits are crucial for effective groundwater management and mining operations. This study investigates the hydrogeochemistry of the Golgohar Mines in south-central Iran, focusing on Mine Pit No. 2 and the Kheirabad Salt Pan, using a multi-proxy approach that includes Self-Organizing Maps (SOM), Hierarchical Clustering Analysis (HCA), hydrochemical diagrams, and stable isotopic analysis (δ 2 H, δ 18 O) and tritium. 20 sampling points were selected for hydrogeochemical analyses, 16 sampling points for stable isotopes of δ 18 O and δ 2 H, and 4 samples for the tritium radioisotope, with sampling conducted during both wet and dry seasons. Based on ionic ratio diagrams, halite dissolution is the predominant process contributing to salinity, with additional influences from reverse cation exchange and gypsum dissolution. The main type and facies of all groundwater samples in the region are Na-Cl and Ca-Cl. The alignment of self-organizing maps with HCA and the hydrochemical classification identified four distinct water clusters: Cluster I is associated with the Kheirabad Salt Pan, Cluster II originates from the hard rock aquifer, Cluster III results from the mixing of multiple sources, including the alluvial aquifer, hard rock aquifer, and brine from the Kheirabad Salt Pan, and Cluster IV is linked to the alluvial aquifer. A hydraulic and hydrogeochemical relationship was observed between the Kheirabad Salt Pan and Mine Pit No. 2, while the main source of salinity in the hard rock aquifer appears to be unrelated to the Kheirabad Salt Pan, potentially involving extensive mixing with other waters. The study highlights the effectiveness of SOM and HCA in elucidating hydrochemical processes in complex mining environments, offering valuable insights for groundwater management.

During the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March 11, 2011, radionuclides such as tritium were released into the environment across Japan, obscuring the natural background signal of tritium in precipitation. This anthropogenic component was rapidly washed out by precipitation according to measurements in Japan. However, the impact of the accident on the natural tritium-based estimation of water system transit times in Fukushima and other prefectures in Japan remains uncertain. For the first time, anthropogenic tritium from the FDNPP accident together with natural tritium were simulated in an atmospheric general circulation model with a good ability to represent tritium variations in daily and monthly precipitation. For the FDNPP accident, we estimate the maximum tritium atmospheric emission of 0.815 PBq with a tritium in precipitation peak of 68.7 Bq/L (582 tritium units) on March 2011 at Fukushima, which are consistent with previous estimations. Using our modeled outputs with tritium measurements, we improve tritium-tracer application for estimating mean transit times of Fukushima surface and groundwater systems impacted by the anthropogenic tritium from the FDNPP accident. While the anthropogenic impact of the FDNPP accident was limited compared to the tritium peak due to the thermonuclear testing, globally modeled tritium in precipitation is useful to apply for other areas of tritium-tracer studies.

Abstract Investigation on tritium (3H) washout process in a tropical region at Kakrapar Atomic Power Station (KAPS), Gujarat, India was carried out. 3H concentration in air as well as that in rainwater is estimated near KAPS Site having Pressurized Heavy Water Reactors (PHWRs) operational. Samples were collected covering the four rainy seasons from 2016 to 2019. The corresponding meteorological parameters of relative humidity, ambient temperature, wind speed, wind direction, and atmospheric stability were measured. The rain spectral characteristics such as raindrop diameter, fall velocity, liquid water content (LWC) in raindrops and average rain rate are also studied. Site-specific wet deposition rate (Bq m−2 s−1) and washout coefficient for 3H (s−1) is observed to be in the range of 1.4E-05 to 4.8E-01 (Geometric Mean = 5.3E-03) and 1.1E-07 to 3.6E-02 (Geometric Mean = 4.1E-05) respectively. Significant and positive correlation was observed between average rain rate and washout coefficient (R2 = 0.73). Significant and negative correlation was observed between raindrop diameter of different rain events and 3H activity in rainwater (R2 = 0.70).