Long-lived Radionuclides Research Articles

The Challenge of Detecting Remote Spectroscopic Signatures from Radionuclides

The characterization of exoplanetary atmospheres through transit spectra is becoming increasingly feasible, and technology for direct detection remains ongoing. The possibility of detecting spectral features could enable quantitative constraints on atmospheric composition or even serve as a potential biosignature, with the sensitivity of the instrument and observation time as key limiting factors. This paper discusses the possibility that future remote observations could detect the presence of radioactive elements in the atmospheres of exoplanets. Such radionuclides could arise from cosmogenic or geologic sources, as well as from industrial sources, all of which occur on Earth. The detection of radionuclides in an exoplanetary atmosphere could reveal important properties about the planet’s geology or space environment and potentially could serve as a technosignature. However, many radionuclides, including those from industrial sources, attach to aerosol or other particles that cannot be remotely characterized. Limited experimental and theoretical spectral data exist for long-lived radionuclides, but the sensitivity required to detect the spectral features of some known radionuclides would be at least several orders of magnitude greater than required to detect the spectral features of molecular oxygen. Present-day remote spectroscopic observing mission concepts at ultraviolet to mid-infrared wavelengths are not sensitive to discern the presence of radionuclides in exoplanetary atmospheres. Interplanetary fly-by or probe missions may be more likely to provide such data in the future.

Long-lived Gamma-Emitting Radionuclides in Commonly Consumed Imported Coffee Brands in Lagos and the Total Committed Effective Dose using a High Purity Germanium Detector

Long-lived Gamma-Emitting Radionuclides in Commonly Consumed Imported Coffee Brands in Lagos and the Total Committed Effective Dose using a High Purity Germanium Detector

A baseline monitoring of radiological sediment quality and associated risk assessment in coastal ecosystems of the Republic of Congo.

This study presents the first data on levels of natural radioactive elements in sediments from coastal ecosystems of the Republic of Congo. Sediment samples from five coastal sites were collected and analyzed by high-resolution gamma spectrometry for determination of activities of long-lived gamma-emitting radionuclides (234Th, 238U, 226Ra, 210Pb, 228Th, 228Ra, and 40K). The specific activities were of the same order of magnitude as those measured in sediments of most countries neighboring the Republic of Congo. However, variations in activities were observed from one site to another and also from one sampling point to another within the same site without exceeding the global average reference values. It can be assumed, therefore, that no significant anthropogenic impact is perceptible in the study area. The most commonly used radiological hazard parameters, based mainly on 238U, 232Th, and 40K activities, were assessed and the ERICA tool was applied to quantify the radiation exposure burden to human and biota resulting from radionuclides in sediments. Besides being useful for future monitoring efforts, the data produced in this work could be important for the worldwide database on radioactivity in the oceans and seas (MARIS) since no data are available in the Congolese marine environment.

Assessment of metal(loid) and natural radionuclide pollution in surface sediments of an estuary affected by mining and phosphogypsum releases

The prolonged impact over the Tinto River estuary by both the significant pollution by acid mine drainage (AMD) affecting this river and the polluted releases from phosphogypsum (PG) piles has led to the severe environmental degradation of this ecosystem. The aim of this work was to assess the current environmental quality of the Tinto River estuary through the study of the spatial distribution of metal(loid)s and natural radionuclides in the surface sediments from the channel edge. The sediments contain mean concentrations 5–20 times higher than the background values for pollutants such as Zn, As, Cu, Pb, or U, and up to two orders of magnitude higher for P. The studied sediments are heavily polluted by toxic heavy metals and metalloids (Pb, Zn, Cu, and As) according to the US EPA guidelines. Most of the analyzed sediment samples are also strongly polluted by long-lived natural radionuclides, mainly U-isotopes and 210Pb with concentrations up to one order of magnitude higher than unpolluted sediments, mostly due to the contribution by the PG leachates. The enrichment factors (EF) were extremely high (EF > 50) for As and very severe enrichment (25 ≤ EF < 50) for P, Cd, Zn, Cu, and Pb.

Recent Advances in Pretargeted Strategy for Cancer Theranostics.

In nuclear medicine, theranostic probes that combine nuclear imaging capabilities with therapeutic functions have shown promise for the diagnosis and treatment of cancers. Nevertheless, the development of theranostic probes may be constrained by two principal factors: (1) the discrepancy between the slow accumulation time of the probes in the tumours and the short-lived radionuclides, and (2) the suboptimal imaging/treatment effect and high radioactive toxicity caused by long-lived radionuclides. In recent years, pretargeted strategy has been proposed as a potential solution to solve these problems. In the pretargeted strategy, two components consisting of a tumour-targeting vector (e.g., antibody) and a radionuclide are injected separately, which can then couple in the tumour tissues to trap radionuclides for nuclear imaging and/or therapy. This two-step process allows for the independent optimization of the pharmacokinetics of them in vivo, benefiting to improve nuclear imaging and/or therapy of tumours in vivo. In this concept, we will discuss the principle of the pretargeted strategy, with a focus on the discussion of different tumour-targeting vectors, including antibody-mediated delivery, nanoparticle-mediated delivery, metabolic glycan labeling-mediated accumulation, and enzyme-triggered in situ self-assembly-mediated retention. Finally, we will discuss the current challenges and perspectives on their applications for cancer theranostics in clinics.

Pyrochlore-type lanthanide titanates and zirconates: Synthesis, structural peculiarities, and properties

This contribution provides a thorough examination of the structural characteristics of pyrochlore-type lanthanide titanates and zirconates Ln2Ti2O7 and Ln2Zr2O7, across various length scales. This paper also examines their processing, interesting physical properties (electrical, magnetic, and thermal characteristics), and responses to high pressure and ion irradiation. Brief sections on the elemental oxides' crystal chemistry, pertinent phase diagrams, and energetics of defect formation are also provided. Pyrochlore-type Ln2Ti2O7 and Ln2Zr2O7 stand out as truly multifunctional materials. Moreover, they have emerged as fascinating materials due to magnetic geometrical frustration, arising from the ordering of magnetic Ln3+ and non-magnetic Ti4+ (or Zr4+) cations into separate, interpenetrating lattices of corner-sharing tetrahedra. This results in a diverse array of exotic magnetic ground states, such as spin-ice (e.g., Dy2Ti2O7 or Ho2Ti2O7) or quantum spin ice (e.g., Tb2Ti2O7), observed at both low and room temperatures. They also exhibit varied electrical and electrochemical characteristics. Some members such as Gd2Zr2O7, function as fast ion conductors with a conductivity (σ) of ≈10−2 S·cm−1 at 800 °C and activation energy (Ea) ranging from 0.85 to 1.52 eV, depending on the degree of structural disorder. Others, such as Gd2TiMoO7, are mixed ionic-electronic conductors with σ ≈ 25 S·cm−1 at 1000 °C, making them promising candidate materials for applications in energy conversion and storage devices and oxygen separation membranes. Their exceptionally low thermal conductivity (e.g., κ ∼ 1.1–1.7 W·m−1·K−1 between 700 and 1200 °C for Ln2Zr2O7), close to the glass-like lower limit of highly disordered solids, positions them as valuable materials for thermal barrier coatings. They can also effectively accommodate actinides (e.g., Pu, Np, Cm, Am) in solid solutions and sustain prolonged exposure to radiation due to alpha-decay events, while preserving the integrity of the periodic atomic structure. Proposed as major components in actinide-bearing ceramics, they contribute to the long-term immobilization and disposal of long-lived waste radionuclides from nuclear programs. Some of these properties are displayed simultaneously, opening avenues for new applications. Despite the wealth of data available in the literature, this review highlights the need for a better understanding of order/disorder processes in pyrochlore-type materials and the influence of the structural length scale on their physical and chemical properties. Recent experimental evidence has revealed that pyrochlore short-range structure is far more complex than originally thought. Moreover, pyrochlore local structure is now believed to include short-range, lower symmetry, ordered domains, such as the orthorhombic weberite-type of structure. Notably, short- and long-range structures appear decoupled across different length scales and temperature regimes, and these differences persist even in well-ordered samples. We believe that the pyrochlore structure offers a unique opportunity for examining the interplay between chemical composition, defect chemistry, and properties. In Memoriam: Rodney C. Ewing, Fondly Remembered.

Radionuclides in marine sediment

Abstract Most contaminants in the sea originate from land sources. Radionuclides in sea water are transported by sea currents. Marine sediment is a physical trap for pollutants that are introduced to the environment and play an important role in radiological studies. Radionuclides from seawater bound to particulates sink to the seabed. Their resuspension causes the reintroduction of pollutants to the water column. Remobilization and horizontal/vertical transport by various processes may occur. Long-lived radionuclides become buried in sub-surface sediment. Grain size sediment classification and sediment geochemical composition all play a significant role in the development of the radionuclide content of marine sediment. Atmospheric fallout from the Chernobyl and the Fukushima accidents, atmospheric nuclear weapon testing, releases from nuclear industry plants, river runoff, and to a lesser extent directed and submarine groundwater discharges are the major sources of radionuclides in the marine environment.

Case studies of three geological archives for rare radionuclide measurements using accelerator mass spectrometry

Long-lived radionuclides in our environment provide important information on natural and anthropogenic processes. Their presence and concentration reflect the balance of production and decay. Geological archives store such information and the nuclides can be chemically extracted from the bulk sample. Accelerator mass spectrometry (AMS) represents a sensitive method to quantify those nuclides at natural levels. Three different terrestrial archives are discussed here as examples for radionuclide extraction using various chemical separation methods for subsequent AMS measurements. We focus on sample preparation for the cosmogenic radionuclides 10Be and 26Al, various anthropogenic actinide isotopes such as U, Pu, and Am as well as the astrophysically interesting nuclides 41Ca, 53Mn, and 60Fe. The processed materials cover samples with masses between a few mg and up to a few hundred kg and protocols are presented for the quantitative extraction of some 10,000 atoms of cosmogenic or interstellar origin per sample and even as low as a few hundred actinide atoms.

Thermal Effects and Glass Crystallization in Composite Matrices for Immobilization of the Rare-Earth Element–Minor Actinide Fraction of High-Level Radioactive Waste

The current policy of managing high-level waste (HLW) derived in the closed nuclear fuel cycle consists in their vitrification into B-Si or Al-P vitreous forms. These compounds have rather limited capacity with respect to the HLW (5–20 wt%), and their properties change over time due to devitrification of the glasses. Cardinal improvement in the management of HLW can be achieved by their separation onto groups of elements with similar properties, followed by their immobilization in robust waste forms (matrices) and emplacement in deep disposal facilities. One of the possible fractions contains trivalent rare-earth elements (REEs) and minor actinides (MAs = Am and Cm). REEs are the fission products of actinides, which are mainly represented by stable isotopes of elements from La to Gd as well as Y. This group also contains small amounts of short-lived radionuclides with half-lives (T1/2) from 284 days (144Ce) to 90 years (151Sm), including 147Pm (T1/2 = 2.6 years), 154Eu (T1/2 = 8.8 years), and 155Eu (T1/2 = 5 years). However, the main long-term environmental hazard of the REE–MA fraction is associated with Am and Cm, with half-lives from 18 years (244Cm) to 8500 years (245Cm), and their daughter products: 237Np (T1/2 = 2.14 × 106 years), 239Pu (T1/2 = 2.41 × 104 years), 240Pu (T1/2 = 6537 years), and 242Pu (T1/2 = 3.76 × 105 years), which should be immobilized into a durable waste form that prevents their release into the environment. Due to the heat generated by decaying radionuclides, the temperature of matrices with an REE–MA fraction will be increased by hundreds of centigrade above ambient. This process can be utilized by selecting a vitreous waste form that will crystallize to form durable crystalline phases with long-lived radionuclides. We estimated the thermal effects in a potential REE–MA glass composite material based on the size of the block, the content of waste, the time of storage before immobilization and after disposal, and showed that it is possible to select the waste loading, size of blocks, and storage time so that the temperature of the matrix during the first decades will reach 500–700 °C, which corresponds to the optimal range of glass crystallization. As a result, a glass–ceramic composite will be produced that contains monazite ((REE,MA)PO4) in phosphate glasses; britholite (Cax(REE,MA)10-x(SiO4)6O2) or zirconolite ((Ca,REE,MA)(Zr,REE,MA)(Ti,Al,Fe)2O7), in silicate systems. This possibility is confirmed by experimental data on the crystallization of glasses with REEs and actinides (Pu, Am). The prospect for the disposal of glasses with the REE–MA fraction in deep boreholes is briefly considered.

Plutonium mobility and reactivity in a heterogeneous clay rock barrier accented by synchrotron-based microscopic chemical imaging

The long-term safe disposal of radioactive waste corresponds to a challenging responsibility of present societies. Within deep geological waste disposal concepts, host rocks correspond to the ultimate safety barrier towards the environment. To assess the performance of such barriers over extended time scales, mechanistic information on the interaction between the radiotoxic, long-lived radionuclides like plutonium and the host rock is essential. Chemical imaging based on synchrotron microspectroscopic techniques was used to visualize undisturbed reactive transport patterns of Pu within pristine Opalinus Clay rock material. Pu+V is shown to be progressively reduced along its diffusion path to Pu+IV and Pu+III due to interaction with redox-active clay rock constituents. Experimental results and modeling emphasize the dominant role of electron-transfer reactions determining the mobility of Pu in reactive barrier systems. The effective migration velocity of Pu is controlled by the kinetic rates of the reduction to Pu+IV and Pu+III and the redox capacity of the involved electron donor pools. To advance our predictive capabilities further, an improved understanding of the nature and capacity of redox-active components of the reactive barrier material is fundamental. The findings represent an essential contribution to the evaluation of the long-term safety of potential nuclear waste repositories and have implications regarding the development of effective geological disposal strategies.

Lithium extraction from geothermal brines: Adsorption-desorption studies on 226Ra (228Ra) and 210Pb on lithium-titanium-oxides (LTO)

Extracting lithium from geothermal brines contributes to meet the growing demand for lithium-ion batteries and other energy applications. Deep geothermal brines of the Upper Rhine Graben (URG) contain up to 200 mg L−1 of lithium and a wide range of dissolved elements, including Th–U series radionuclides. This study presents data from a radiochemical monitoring conducted as part of pilot tests for lithium extraction at the Bruchsal geothermal site under site-specific thermodynamic conditions (T = 60 °C; p = 18 bar). The results show an uptake of the long-lived radionuclides 226Ra (228Ra) and 210Pb by the granulated lithium-titanium-oxide (LTO) sorbent employed. Increasing pH values favor the adsorption of the naturally occurring radionuclide, due to increasing negative charge of the LTO surface. The radioactive uptake of radium was found to be nearly in adsorption equilibrium state after 12 extraction cycles performed. In contrast, 210Pb is permanently removed from the Bruchsal brine by more than 96 % reflecting its high capability to approach the adsorbent surface during adsorption compared to the competing cations. Radioactive load of both radium and lead isotopes on the LTO adsorbent could be reduced using 0.5 M HCl as desorption agent. In this context, desorption percentages ranging from 50 to 100 % per extraction cycle were obtained.

Lithium recovery from geothermal brines: An investigation into radioactive nuclide uptake on lithium‑manganese-oxide (LMO) granules

Due to the growing demand for lithium, the exploitation of non-conventional lithium sources such as Li-bearing geothermal brines is currently on the rise. These brines contain up to 200 mg L−1 of lithium along with a diverse range of other dissolved elements, including naturally occurring radionuclides. In this study, data from a radiochemical monitoring process performed during the pilot plant testing of direct lithium extraction (DLE) at a geothermal site in the Upper Rhine Graben (URG) are presented. The tests were conducted under thermodynamic p-T conditions of the geothermal plant (T = 60 °C, p = 18 bar). The results present an uptake of the long-lived radionuclides 226Ra (228Ra) and 210Pb by the granulated lithium‑manganese-oxides (LMO) sorbent employed. Elevated pH values enhance the sorption of nuclides formed in the Th-U decay series, due to the increased negative charge on the LMO surface. The radioactivity uptake on the sorbent was found to be time-dependent. Experiments with a 5-min contact time resulted in relatively low sorption capacities, while extending the sorption time to 30 min significantly increased the accumulation of Ra isotopes and 210Pb on the sorbent surface. During the regeneration phase, the radioactive load on the LMO sorbent could be reduced using 0.5 M HCl. The mass balance analysis of the investigated radionuclides demonstrates desorption percentages ranging from 16% to 100% per extraction cycle.

M-FISH evaluation of chromosome aberrations to examine for historical exposure to ionising radiation due to participation at British nuclear test sites

Veterans of the British nuclear testing programme represent a population of ex-military personnel who had the potential to be exposed to ionising radiation through their participation at nuclear testing sites in the 1950s and 1960s. In the intervening years, members of this population have raised concerns about the status of their health and that of their descendants, as a consequence. Radiation dose estimates based on film badge measurements of external dose recorded at the time of the tests suggest any exposure to be limited for the majority of personnel, however, only ∼20% of personnel were monitored and no measurement for internalised exposure are on record. Here, to in-part address families concerns, we assay for chromosomal evidence of historical radiation exposure in a group of aged nuclear test (NT) veterans, using multiplex in situ hybridisation (M-FISH), for comparison with a matched group of veterans who were not present at NT sites. In total, we analysed 9379 and 7698 metaphase cells using M-FISH (24-colour karyotyping) from 48 NT and 38 control veteran samples, representing veteran servicemen from the army, Royal Airforce and Royal Navy. We observed stable and unstable simple- and complex-type chromosome aberrations in both NT and control veterans’ samples, however find no significant difference in yield of any chromosome aberration type between the two cohorts. We do observe higher average frequencies of complex chromosome aberrations in a very small subset of veterans previously identified as having a higher potential for radiation exposure, which may be indicative of internalised contamination to long-lived radionuclides from radiation fallout. By utilising recently published whole genome sequence analysis data of a sub-set of the same family groups, we examined for but found no relationship between paternal chromosome aberration burden, germline mutation frequency and self-reported concerns of adverse health in family members, suggesting that the previously reported health issues by participants in this study are unlikely to be associated with historical radiation exposure. We did observe a small number of families, representing both control and NT cohorts, showing a relationship between paternal chromosome aberrations and germline mutation sub-types which should be explored in future studies. In conclusion, we find no cytogenetic evidence of historical radiation exposure in the cohort of nuclear veterans sampled here, offering reassurance that attendance at NTs sites by the veterans sampled here, was not associated with significant levels of exposure to radiation.

TRU utilization and MA transmutation in thorium-based fluorinated molten salt fast reactor

In this paper, a thorium-based fluorinated molten salt fast neutron reactor is taken as the research object, and the utilization of thorium resources, reuse of transuranic waste (TRU), and transmutation of minor actinide (MA) in fast reactor are the research purpose. The fast reactor adopts a multi-layer core structure, in which the fuel is divided into an inner fission fuel zone and an outer breeding fuel layer, respectively loaded with fluorinated molten salts LiF+ThF4+XF4 (where X is 233U, TRU, or 233U+MA) and LiF+ThF4. In addition to serving as nuclear fuel, these two molten salts also act as coolants in the primary circuits.Through the cross sections of nuclear reactions, transmutation chain of actinide nuclides, and the particle population density formula of actinide nuclides in nuclear reaction equilibrium, the possible nuclear reactions of actinide nuclides in thorium-based fast reactors are analyzed. The calculated results show that the thorium-based fast reactor has the following characteristics: fast neutron energy spectrum, negative temperature reactivity coefficient, effective utilization of thorium resources, the ability to breed fissle fuel such as 233U, production of high-purity radioisotope 238Pu material, and the ability to incinerate Pu and MAs in the TRU spent fuel.In the 233U fuel scheme, the 233U fuel is breeded, breeding ratio of fissile fuels is 1.21, the reaction products contain very little Np, and almost no Pu, Am, and Cm long-lived radionuclides. In the TRU fuel scheme, the annual capacity to incinerate MAs and Pu is 1072.6 kg, while producing a large amount of 233U and 233Pa fuel (together 1162.5 kg/year).In the 233U+2.0 wt% TRU-MAs fuel scheme, 127.35 kg of MA waste can be incinerated annually, and their transmutation rate is 15.95%, which is equivalent to the annual production of MA nuclear waste from 4.9 conventional 1000 MWe light water reactors. Here, TRU-MAs is the mixtured MA fuels after separation of Pu from the TRU fuel. At the same time, radioactive fuel 238Pu, which can be used for space nuclear power, is produced with an annual yield of 87.89 kg and an isotopic abundance of 87.57%. If the added TRU-MAs fuel is replaced with 2.0 wt% 237Np fluorinated salt, the annual yield and isotope abundance of 238Pu are further increased to 130.24 kg and 95.4%.

A practical method for assessing quantitative scanner accuracy with long-lived radionuclides: The ARTnet insert.

To address the problem of using large volumes of long-lived radionuclides in test phantoms to check calibration accuracy of PET and SPECT systems we have developed a test object which (a) contains less radioactivity, (b) has a low total volume, and (c) is easier to store than currently used phantoms, while still making use of readily-available "standardised" test objects. We have designed a hollow acrylic cylindrical insert compatible with the NEMA/IEC PET Body Image Quality (IQ) phantom used in NU 2 performance testing of PET systems. The insert measures 90 mm internal diameter and 70 mm internal height and so is sufficiently large to not be subject to partial volume effects in PET or SPECT imaging. The volume of the insert is approximately 500 mL. It has been designed as a replacement for the standard long cylindrical "lung insert" in the IQ phantom without needing to remove the fillable hollow spheres of the phantom. The insert been tested with 18F, 68Ga and 124I PET/CT and 99mTc, 131I and 177Lu SPECT/CT on scanners that had previously been calibrated for these radionuclides. The scanners were found to produce accurate image reconstructions in the insert with 5% of the true value without any confounding uncertainty from partial volume effects when compared to NEMA NU 2-2018 Phantom measurement. The "ARTnet Insert" is simple to use, inexpensive, compatible with current phantoms and is suitable for both PET and SPECT systems. It does not suffer from significant partial volume losses permitting its use even with the poor spatial resolution of high-energy imaging with 131I SPECT. Furthermore, it uses less radioactivity in a smaller volume than would be required to fill the entire phantom as is usually done. Long-term storage is practical while allowing radioactive decay of the insert contents.

Investigation of RPV samples of the Greifswald NPP with focus on retrospective dosimetry

Reactor pressure vessel (RPV) samples of units 1 and 4 of the Greifswald NPP were investigated with focus on retrospective dosimetry. Specific activities of long-lived radionuclides 63Ni, 93mNb, 94Nb and 99Tc as well as the concentrations of the producing elements were measured. Investigated samples comprise base metal, welding metal and cladding of the RPV. Neutron fluences obtained with the M onte-Carlo codes TRAM O and M CNP were used to calculate specific activities. The gamma-emitter 94Nb appears as a promising candidate due to the large Nb concentration in the cladding of the VVER RPVs. For 93mNb, a very good agreement of measured und calculated activities was found for the RPV cladding samples where 93mNb is primarily produced by the threshold reaction 93Nb(n,n’)93mNb. A strong scatter of the ratios of calculated and experimental activities is observed for 63Ni which is primarily produced by slow neutrons. For 99Tc, a good agreement of calculated and measured activities was found for the majority of the base metal and welding metal samples but not for the cladding samples. Updated reaction cross section data for 62Ni(n,γ) and 92M o(n,γ) lead to a better agreement of calculated and measured activities for 63Ni and 93mNb.

Salting out of americium-241 in the sorption process using a solid-phase extractant based on TODGA

Today, the «Proryv» project is developing effective methods of reprocessing irradiated nuclear fuel (SNF) to return long-lived radionuclides to the fuel cycle to close it. One of the challenges of closed fuel cycle development is the reprocessing of highly active nitric acid raffinates from the PUREX-process. To achieve this task, it is necessary to separate americium-241 from liquid radioactive waste. When processing and fractionating liquid radioactive waste, extraction and sorption technologies for the extraction, purification and concentration of radionuclides are widely used. The highest efficiency and selectivity in the extraction processes of actinoids (III) and lanthanides (III) with rare earth elements (REE) and transplutonium elements (TPE) from nitric acid solutions of spent nuclear materials reprocessing were shown by extractants based on N, N, N', N'-tetraoctyldiglycolamide (TODGA). Before using a solid-phase extractant based on TOGDA, the ions of the substance in solution must be converted to neutral complexes or other non-dissociated compounds. This can be achieved by adding neutral salts to the solution, which reduce the solubility of the elements to be separated, shift the extraction distribution and significantly increase the extraction efficiency. The extracted substance is extracted in the form of a new phase - solid precipitate, liquid or gas phase, and in the case of liquid extraction there is an increase in the capacity of the extractant for the target component. Therefore, the addition of salts-salting agents to the aqueous phase to increase the ionic strength of the solution increases the distribution coefficients of extracted substances, which in turn increases the capacity of sorbents. The purpose of this work is to study the process of salting out of americium-241 during sorption using an experimental modified sample of solid-phase extractant based on TODGA in the studied model solutions of liquid radioactive waste with a uranium macrocomponent for different NaNO3 contents. The study revealed that the highest distribution coefficients for the sorption of americium-241 and uranium were obtained in a solution containing 100 g/l NaNO3, but for uranium this effect is much less pronounced than for americium-241. During the study of the sorption kinetics of americium-241 and uranium, the salting effect was revealed, which is confirmed by the values of the equilibrium concentrations of americium-241 and uranium in solution at the same time point but with different NaNO3 concentrations. The difference in the equilibrium concentrations for americium-241 was an order of magnitude towards its decrease when NaNO3 concentration was increased up to 100 g/litre. The use of this effect makes it possible to obtain the maximum capacity for americium-241 in the system with uranium macrocomponents

Comparison of external dose estimates using different retrospective dosimetry methods in the settlements located near Semipalatinsk Nuclear Test Site, Republic of Kazakhstan.

For correct assessment of health risks after low-dose irradiation, calculation of radiation exposure estimates is crucial. To verify the calculated absorbed doses, instrumental methods of retrospective dosimetry are used. We compared calculated and instrumental-based estimates of external absorbed doses in the residents of Dolon, Mostik and Cheremushki villages, Kazakhstan, affected by the first nuclear weapon test performed at the Semipalatinsk Nuclear Test Site (SNTS) on August 29, 1949. The 'instrumental' doses were retrospectively estimated using the Luminescence Retrospective Dosimetry (LRD) and Electron Spin Resonance (ESR) methods. Correlation between the calculated individual cumulative external absorbed whole-body doses based on typical input data and ESR-based individual doses in the same people was strong (r = 0.782). It was even stronger between the calculated doses based on individual questionnaires' input data and the ESR-based doses (r = 0.940). Application of the LRD method is useful for validation of the calculated settlement-average cumulated external absorbed dose to air. Reconstruction of external exposure can be supplemented with the data from later measurements of soil contamination with long-lived radionuclides, such as, 137Cs. Our results show the reliability of the calculational method used for the retrospective assessment of individual external doses.

Investigation of the Effect on the Albumin Binding Moiety for the Pharmacokinetic Properties of 68Ga-, 205/206Bi-, and 177Lu-Labeled NAPamide-Based Radiopharmaceuticals.

Although radiolabeled alpha-melanocyte stimulating hormone-analogue NAPamide derivatives are valuable melanoma-specific diagnostic probes, their rapid elimination kinetics and high renal uptake may preclude them from being used in clinical settings. We aimed at improving the pharmacokinetics of radiolabeled DOTA-NAPamide compounds by incorporating a 4-(p-iodo-phenyl)-butanoic acid (IPB) into the molecules. Followed by 68Ga-, 205/206Bi-, and 177Lu-labelling, the radiopharmaceuticals ([68Ga]Ga-DOTA-IPB-NAPamide, [205/206Bi]Bi-DOTA-IPB-NAPamide, [177Lu]Lu-DOTA-IPB-NAPamide) were characterized in vitro. To test the imaging behavior of the IPB-containing probes, B16F10 tumor-bearing C57BL/6 mice were subjected to in vivo microPET/microSPECT/CT imaging and ex vivo biodistribution studies. All tracers were stable in vitro, with radiochemical purity exceeding 98%. The use of albumin-binding moiety lengthened the in vivo biological half-life of the IPB-carrying radiopharmaceuticals, resulting in elevated tumor accumulation. Both [68Ga]Ga-DOTA-IPB-NAPamide (5.06 ± 1.08 %ID/g) and [205/206Bi]Bi-DOTA-IPB-NAPamide (4.50 ± 0.98 %ID/g) exhibited higher B16F10 tumor concentrations than their matches without the albumin-binding residue ([68Ga]Ga-DOTA-NAPamide and [205/206Bi]Bi-DOTA-NAPamide: 1.18 ± 0.27 %ID/g and 3.14 ± 0.32; respectively), however; the large amounts of off-target radioactivity do not confirm the benefits of half-life extension for short-lived isotopes. Enhanced [177Lu]Lu-DOTA-IPB-NAPamide tumor uptake even 24 h post-injection proved the advantage of IPB-based prolonged circulation time regarding long-lived radionuclides, although the significant background noise must be addressed in this case as well.

The presence of NORMs and toxic heavy metals in talcum baby powder

Baby talcum powder is one of the popular baby care products used for keeping the baby's skin dry and preventing diaper rash. In the past few years, there has been a growing concern on the presence of toxic heavy metals within the baby talcum powder due to its potential threat to human health and environmental effects. However, its natural radioactivity content is much less considered where it may pose similar health risks to the consumers. The present study examines the radioactivity and heavy metals concentration towards the commonly used baby powders in Malaysia, including Pureen, Johnson's, Carrie Junior and Zwitsal, utilizing the High Purity Germanium (HPGe) gamma-ray spectrometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Individual health risk assessment has been conducted through the estimation of absorbed dose rate due to the exposure of ionizing radiation from the three long-lived primordial radionuclides of 226Ra, 228Ra and 40K through the usage of baby powders. The assessment revealed that an individual might be exposed to an average radiation dose rate of 0.518 pGy h−1, albeit lower than the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) reference exposure dose limit of 59 nGy h−1 for terrestrial radionuclides. In regards to heavy metals toxicity, all baby powders are within the permissible limits of heavy metals concentration recommended by the National Pharmaceuticals Regulatory Agency (NPRA), ASEAN Cosmetic Scientific Body (ACSB) and the United States Food and Drug Administration (FDA) except for Ni where its concentrations were slightly above the permissible value of 0.6 ppm outlined by FDA. Prolonged use of baby powders contaminated with such heavy metal may pose a significant risk to human health and the environment due to its toxic metal loading. These results emphasize the need for periodic monitoring and quality control of baby powders to ensure they meet safety standards and minimize potential risks to human health and the environment.