High Gamma-ray Research Articles

Ionizing Radiation Dose to the Skin Assessed after Rapid Detection of 232Th in Consumer Products.

After some consumer products indicated elevated levels of 232Th progeny by gamma-ray spectrometry, a microwave digestion and inductively coupled plasma-mass spectrometry (ICP-MS) procedure was implemented for the direct assay of 232Th content to ensure compliance with Federal regulations and guidelines. Levels of 232Th were determined by ICP-MS based on standard calibration using a 205Tl internal standard. The method had a method detection limit (MDL) of 0.15 Bq g-1 and a lower limit of quantification (LLOQ) of 0.65 Bq g-1 for 232Th, making it a suitable confirmatory method following gamma-ray spectrometry. The 232Th activity concentration calculated from the ICP-MS results ranged from 2.0-3.4 Bq g-1 for the kinesiology tape samples and 20 Bq g-1 for the silicone ion bracelet. The VARSKIN+1.0 software program was used to calculate the shallow dose equivalent of ionizing radiation from 232Th and its progeny from the ICP-MS results. The skin dose to the consumer wearing the kinesiology tape ranged from 0.48-1.6 mSv y-1. The skin dose to the consumer with constant wear of the silicone ion bracelet was estimated to be 17 mSv y-1. Although 232Th may be determined indirectly by assay of high abundance gamma rays produced by its progeny, the US Code of Federal Regulations (CFR) requires the direct assay of 232Th for confirmatory analysis. We found this ICP-MS method to be a rapid 232Th confirmatory technique compared to a chemical separation followed by alpha spectrometry procedure.

Influence of the gamma source on the radiolytic stability of N,N,N′,N′-tetra-n-octyl-diglycolamide (TODGA)

Abstract In nuclear reprocessing, hydrolytic and radiolytic stability of ligands, extractants, diluents and solvents is of particular importance. The strength of extraction systems can only be fully exploited when process conditions are predictable and essential molecules, which are in close proximity to radioactive isotopes, are resistant to the radiation. During the development of novel extraction systems, testing of the radiolytic stability is often evaluated by exposing the molecules to high energetic gamma rays. In this work, the influence of the source of gamma rays is evaluated. TODGA was irradiated from 0–500 kGy using different sources of gamma rays, and its degradation was followed using UPLC-HRMS. Pool-type gamma irradiation facilities BRIGITTE B (Co-60) and GEUSE II (spent nuclear fuel) at SCK CEN were employed to serve as gamma sources. In this work, it is found that there is no significant influence on TODGA degradation which can be attributed to the origin of the gamma source.

In-situ detection of high-energy beta ray emitter 90Sr/90Y inside the Fukushima Daiichi Nuclear Power Station Unit 3 reactor building using a liquid light guide Cherenkov counter

We have developed a method to directly detect 90Sr/90Y under a high gamma ray background using a liquid light guide Cherenkov counter. Cherenkov radiation has the characteristic that the angle of radiation varies depending on the energy of the charged particles. Using this feature, we have developed a surface contamination detector capable of discriminating between 662 keV gamma rays from 137Cs and beta rays from 90Sr/90Y through time-of-flight analysis of the Cherenkov radiation generated inside the liquid light guide. With this detector, we conducted a measurement test of 90Sr/90Y inside the Fukushima Daiichi Nuclear Power Station Unit 3 reactor building and achieved the first in-situ detection of 90Sr/90Y under a high gamma-ray background.

Tectono-sedimentary evolution and oil-gas geological significance of first to third member of Ordovician Majiagou Formation in Ordos Basin, NW China

Based on logging, core, thin section and geochemical analysis, the tectonic-lithofacies paleogeographic pattern of first member to third member of Ordovician Majiagou Formation (O1m1–O1m3 for short) in Ordos Basin is reconstructed, and the tectono-sedimentary evolution characteristics and oil-gas geological significance are discussed. The results are obtained in four aspects. First, a set of marginal argillaceous dolomites with high gamma ray value developed steadily and diachronously at the bottom of Majiagou Formation, which distributed over the Huaiyuan Movement unconformity, with δ13C values positive drift characteristics comparable to global transgression of the Early Ordovician Floplian. Second, the global sea level rose and the ancient land was submerged into the underwater uplift in O1m1 to O1m2, and the central uplift was deposited for the first time in the Ordovician, forming a tectonic pattern of “one uplift and two depressions”. Subsequently, the subduction and extrusion outside the basin and the differentiation of uplift and depression in the basin of O1m3 resulted in the activation of the Wushenqi–Jingbian bulge. Third, the evolution of the tectonic pattern had a significant impact on the sedimentary paleoenvironment. The O1m1 overlaps westward, and saline lagoon is formed in eastern depression and influenced by the transgression. The transgression continued in O1m2 and resulted in communication with the wide sea, and the large-scale grain shoal developed around eastern depression, and the late dry shrinkage formed a small scale evaporite lagoon in upper part. Under the influence of highland sealing in O1m3, the water body gradually differentiated into dolomitic gypsum and saline lagoons to the east, and the grain shoal spread along the highs around sag. Fourth, the source rocks developed diachronously at the bottom of Majiagou Formation form a favorable source-reservoir assemblage with the shoal facies reservoir distributed around the slope of O1m2–O1m3, and they have certain exploration potential for natural gas.

Radioactive Gamma-Ray Lines from Long-lived Neutron Star Merger Remnants

The observation of a kilonova AT2017gfo associated with the gravitational wave event GW170817 provides the first strong evidence that neutron star mergers are dominant contributors to the production of heavy r-process elements. Radioactive gamma-ray lines emitted from neutron star merger remnants provide a unique probe for investigating the nuclide composition and tracking its evolution. In this work, we studied the gamma-ray line features arising from the radioactive decay of heavy nuclei in the merger remnants based on the r-process nuclear reaction network and the astrophysical inputs derived from numerical relativity simulations. The decay chain of 50126 Sn (T 1/2 = 230 kyr) → 51126 Sb (T 1/2 = 12.35 days) → 52126 Te (stable) produces several bright gamma-ray lines with energies of 415, 667, and 695 keV, making it the most promising decay chain during the remnant phase. The photon fluxes of these bright gamma-ray lines reach ∼10−5 γ cm−2 s−1 for Galactic merger remnants with ages less than 100 kyr, which can be detected by the high energy resolution MeV gamma-ray detectors like the MASS mission.

Fracture stratigraphy in oil-rich shale of the Upper Xiaganchaigou Formation (upper Eocene), western Qaidam Basin

Natural fractures in wells from oil-rich shale of the Upper Xiaganchaigou Formation in Qaidam Basin, the largest Cenozoic sedimentary basin in the Tibetan Plateau, vary systematically by stratigraphic position, allowing reconstruction of fracture generation processes during regional tectonic deformation. Compacted fractures, layer-bounded fractures, and low-angle (or bed-parallel) fractures were widely identified in oil-rich shale cores obtained from vertical wells. The layer-bounded fractures can be subdivided into two sets: one prevalent in light-colored (low gamma-ray) stiff layers and arrested by dark-colored (high gamma-ray) compliant layers, the other set primarily confined to the dark-colored compliant layers. The strikes of layer-bounded fractures, revealed by horizontal well FMI logs, are dominantly N60°-80°E and N10°-30°E within the light and dark intervals respectively. These strikes are consistent with natural hydraulic fracturing of the light layers during the Oligocene and the dark layers during the Middle Miocene-Holocene, based on a regional anticlockwise rotation of the compressional strain orientation. The abutment of layer-bounded fractures against low-angle (or bed-parallel) fractures in dark layers implies that the low-angle fractures were hydraulically fractured under a vertical least compressive stress during the Early Miocene, which produced the most intense tectonic compression. Layer-bounded fractures generally remain unmineralized in the dark layers but were mineralized in the light layers, suggesting that fractures confined in light layers would not decrease the sealing capacity of the shale oil system and fractures confined in dark layers can increase the pore space of shale oil storage. The Oligocene and Early Miocene fractures represented mechanical flaws that affected the initiation of Middle Miocene-Holocene fractures, implying that all natural fractures may alter hydraulic fracture stimulations to some extent.

Assessment of Natural Occurring Radioactive Materials and Radiological Hazards Exposure in Soil of Ohia in Umuahia South Abia State Nigeria, Using High Purity Germanium (HPGe) Gamma Ray Spectrometry

Evaluation of natural occurring radioactive materials (NORMs) and radiological exposure are important. The main goal of this work was to determine the NORMs level and radiological exposure risk in Umuahia, using High Purity Germanium Gamma Ray Spectrometry at IPEN, Brazil. The radionuclides (RDNs) such as: 40K, 226Ra and 232Th and radiological parametric indices (RPIs) such as: Absorbed Dose Rate in Air (D), Outdoor and Indoor Annual Effective Dose Equivalent (AEDE), Radium Equivalent Activity (Raeq), Annual Gonadal Equivalent Dose (AGED) and Activity Concentration Index (I) were determined. The mean values of 40K, 226Ra and 232Th in Bq kg-1 were: 147, 28, and 31 while the RPIs mean values for D, ,, AGED, Raeq, and I are: 37 nGy h-1, 0.05 mSv y-1, 0.18 mSv y-1, 260 y-1, 83 Bq kg-1 and 0.29 respectively. Mean value of RDNs were found to be lower than 412 Bq kg-1, 32 Bq kg-1 and 35 Bq kg-1 average value while RPIs were also lower than 59 nGy h-1, 0.08 mSv y-1 for , 0.42 mSv y-1, 300 y-1 for AGED, 370 Bq kg-1 for Raeq, and 1 mSv y-1 respectively global safe limit or mean values. It is concluded that the soil is radiological safe for agriculture, building and construction purposes.

Assessment of Natural Occurring Radioactive Materials and Radiological Hazards Exposure in Soil of Ohia in Umuahia South Abia State Nigeria, Using High Purity Germanium (HPGe) Gamma Ray Spectrometry

Evaluation of natural occurring radioactive materials (NORMs) and radiological exposure are important. The main goal of this work was to determine the NORMs level and radiological exposure risk in Umuahia, using High Purity Germanium Gamma Ray Spectrometry at IPEN, Brazil. The radionuclides (RDNs) such as: 40K, 226Ra and 232Th and radiological parametric indices (RPIs) such as: Absorbed Dose Rate in Air (D), Outdoor and Indoor Annual Effective Dose Equivalent (AEDE), Radium Equivalent Activity (Raeq), Annual Gonadal Equivalent Dose (AGED) and Activity Concentration Index (I) were determined. The mean values of 40K, 226Ra and 232Th in Bq kg-1 were: 147, 28, and 31 while the RPIs mean values for D, ,, AGED, Raeq, and I are: 37 nGy h-1, 0.05 mSv y-1, 0.18 mSv y-1, 260 y-1, 83 Bq kg-1 and 0.29 respectively. Mean value of RDNs were found to be lower than 412 Bq kg-1, 32 Bq kg-1 and 35 Bq kg-1 average value while RPIs were also lower than 59 nGy h-1, 0.08 mSv y-1 for , 0.42 mSv y-1, 300 y-1 for AGED, 370 Bq kg-1 for Raeq, and 1 mSv y-1 respectively global safe limit or mean values. It is concluded that the soil is radiological safe for agriculture, building and construction purposes.

Curvature in the very-high energy gamma-ray spectrum of M 87

The radio galaxy M 87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares, which were reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is not yet fully understood. In this study, we investigate the VHE gamma-ray spectrum of M 87 during states of high gamma-ray activity, utilizing 20.2 h of H.E.S.S. observations. Our findings indicate a preference for a curved spectrum, characterized by a log-parabola model with extra-galactic background light (EBL) model above 0.3 TeV at the 4σ level, compared to a power-law spectrum with EBL. We investigate the degeneracy between the absorption feature and the EBL normalization and derive upper limits on EBL models that are mainly sensitive in the wavelength range of 12.4 μm–40 μm.

An extensive assessment of the impacts of BaO on the mechanical and gamma-ray attenuation properties of lead borosilicate glass

The current work deals with the synthesis of a new glass series with a chemical formula of 5Al2O3–25PbO–10SiO2–(60-x) B2O3–xBaO; x was represented as 5, 10, 15, and 20 mol%. The FT-IR spectroscopy was used to present the structural modification by rising the BaO concentration within the synthesized glasses. Furthermore, the impacts of BaO substitution for B2O3 on the fabricated borosilicate glasses were investigated using the Makishima-Mackenzie model. Besides, the role of BaO in enhancing the gamma-ray shielding properties of the fabricated boro-silicate glasses was examined utilizing the Monte Carlo simulation. The mechanical properties evaluation depicts a reduction in the mechanical moduli (Young, bulk, shear, and longitudinal) by the rising of the Ba/B ratio in the fabricated glasses. Simultaneously, the micro-hardness boro-silicate glasses was reduced from 4.49 to 4.12 GPa by increasing the Ba2+/B3+ ratio from 0.58 to 3.18, respectively. In contrast, the increase in the Ba/B ratio increases the linear attenuation coefficient, where it is enhanced between 0.409 and 0.448 cm−1 by rising the Ba2+/B3+ ratio from 0.58 to 3.18, respectively. The enhancement in linear attenuation coefficient decreases the half-value thickness from 1.69 to 1.55 cm and the equivalent thickness of lead is also reduced from 3.04 to 2.78 cm, at a gamma-ray energy of 0.662 MeV. The study shows that the increase in the Ba2+/B3+ ratio enhances the radiation shielding capacity of the fabricated glasses however, it slightly degrades the mechanical properties of the fabricated glasses. Therefore, glasses with high ratios of Ba2+/B3+ have high gamma-ray shielding ability to be used in hospitals as a shielding material.

Using N-I-N Photodiodes Made of Perovskite Single Crystals for Low Noise Gamma-Ray Spectroscopy.

Solution-processed lead halide perovskite single crystals (LHPSCs) are believed to have great potential in gamma-ray spectroscopy. However, obtaining low-defect LHPSCs from a solution at low temperatures is difficult compared to obtaining Bridgman single crystals such as CdTe and Si. Herein, noise from the intrinsic defects of LHPSCs is considered as the main problem hindering their gamma-ray detection performance. By isolating the defect-induced holes in LHPSCs via energy barriers, we show that NIN photodiodes based on three types of LHPSCs, i.e., MAPbBr3 (MA = CH3NH3), MAPbBr2.5Cl0.5, and cascade LHPSCs, have demonstrated good energy resolution in the range of 6.7-10.3% for 662 keV 137Cs gamma-ray photons. The noise for >10 mm3 devices is low, in the order of 340-860 electrons, and the electron collection efficiency reaches 23-43%. These results pave the way for obtaining low-cost, large, high energy-resolution gamma-ray detectors at room temperature (300 K).

Influence of various metal oxides (PbO, Fe2O3, MgO, and Al2O3) on the mechanical properties and γ-ray attenuation performance of zinc barium borate glasses

The current work aims to fabricate metal oxide-doped (PbO, Fe2O3, MgO, and Al2O3, each of which boasts a purity of 99%) zinc barium borate glasses through the melt quenching technique at the 1000 °C melting temperature. The results showed that adding 5 mol.% of metal oxides PbO, Fe2O3, Al2O3, and MgO increases the density of the zinc barium borate glasses. Additionally, the fabricated glasses' mechanical properties were determined based on the Makishima-Mackenzie model, which proved that the highest mechanical properties were achieved for glasses doped with Al2O3 compounds. The mechanical moduli for the glasses doped with Al2O3 reach 80.95 GPa (Young), 59.90 GPa (bulk), 31.75 GPa (shear), and 102.23 GPa (longitudinal). Additionally, the Al2O3-doped glasses' microhardness reaches 4.77 GPa. Moreover, estimation of the fabricated glasses' gamma-ray shielding capacity utilized Monte Carlo simulation. The highest linear attenuation coefficients are 29.132, 19.906, 19.243, and 18.923 cm−1 obtained at 0.033 MeV for glasses dopped by PbO, Fe2O3, MgO, and Al2O3, respectively. Therefore, glasses doped with 5 mol.% of PbO have high gamma-ray shielding capacities followed by glasses doped by Fe2O3.

Fabrication of slag/CKD one-mix geopolymer cement reinforced by low-cost nano-particles, mechanical behavior and durability performance

CKD is a byproduct of the cement industry, and its accumulation in the surrounding represents one of many issues associated with this industry. In this study, CKD was utilized in the fabrication of one-mix geopolymer cement (GP) composite as an economical and environmental solution for disposal of this byproduct. The mechanical properties and durability behavior during various deterioration actions were inspected. The obtained findings demonstrated that, replacing slag by CKD in the fabricated GP could cause an elongation in the setting times and reduction in the compression strength of approximately 50%. However, GPs containing CKD offered an accepted resistance to irradiation by γ-rays and to firing action. Reinforcing the GPs with nano Fe3O4 (NF) or nano TiO2 (NT) accelerated the geopolymerization reaction and offered mechanical properties surprising the control mix, this was related to the micro-filling and catalytic actions of the NPs which supported the formation of symmetrical and organized clusters of CSHs and CASH gel as shown in SEM micrographs. The reinforcing mixes surpassing the control mix in the protection against intrusion of sulfate ions which they could retain about 92% of their strength after 4 months of exposure while the control mix retained 80%. Furthermore, they showed a superior resistance to the destructive effect of irradiation by high dose gamma rays up to 1500 kGy and they retained ~ 75% of their strength after irradiation while the control mix was kept at only 35%. The fabricated composites are recommended for usage in many applied construction fields.

Exploring one giga electronvolt cosmic gamma rays with a Cherenkov plenoscope capable of recording atmospheric light fields, Part 1: Optics

Detecting cosmic gamma rays at high rates is the key to time-resolve the acceleration of particles within some of the most powerful events in the universe. Time-resolving the emission of gamma rays from merging celestial bodies, apparently random bursts of gamma rays, recurring novas in binary systems, flaring jets from active galactic nuclei, clocking pulsars, and many more became a critical contribution to astronomy. For good timing on account of high rates, we would ideally collect the naturally more abundant, low energetic gamma rays in the domain of one giga electronvolt in large areas. Satellites detect low energetic gamma rays but only in small collecting areas. Cherenkov telescopes have large collecting areas but can only detect the rare, high energetic gamma rays. To detect gamma rays with lower energies, Cherenkov-telescopes need to increase in precision and size. But when we push the concept of the –far/tele– seeing Cherenkov telescope accordingly, the telescope’s physical limits show more clearly. The narrower depth-of-field of larger mirrors, the aberrations of mirrors, and the deformations of mirrors and mechanics all blur the telescope’s image. To overcome these limits, we propose to record the –full/plenum– Cherenkov-light field of an atmospheric shower, i.e. recording the directions and impacts of each individual Cherenkov photon simultaneously, with a novel class of instrument. This novel Cherenkov plenoscope can turn a narrow depth-of-field into the perception of depth, can compensate aberrations, and can tolerate deformations. We design a Cherenkov plenoscope to explore timing by detecting low energetic gamma rays in large areas.

High count rate gamma ray pile-up correction method of NaI(Tl) detector based on deconvolution method

The output pulses of NaI(Tl) detectors have long tails due to the long decay constant of their output circuits, and these pulses easily pile up in high-count-rate environments. In this study, we used digital deconvolution combined with a digital filtering algorithm to restore piled-up pulses as separate, narrow, Gaussian-like pulses. Radioactive isotopes were used to calibrate the amplitudes of the signals processed by the proposed method. The gamma spectra with different methods were obtained to verify the proposed methods. Count rates were tested at various source-detector distances, and Monte Carlo simulation data verified that the error was within 14.60 % for count rates up to 1661 kHz. Compared to a commercial digitizer, for event rates up to 851 kHz, the proposed method increased the count rate by a factor of 53 and increased the energy resolution from 21.44 % to 15.50 %, while the energy resolution without pile-up was the same as that of the digitizer.

Stratigraphic architecture of the Belly River Group (Campanian, Cretaceous) in the plains of southern Alberta: Revisions and updates to an existing model and implications for correlating dinosaur-rich strata.

The Upper Cretaceous (Campanian) Belly River Group (BRG) of southern Alberta has a complex internal stratigraphic architecture derived from differential geometries of its component formations that resulted from regionalized tectonic influences and shifting source areas. A full understanding of BRG architecture has been compromised heretofore by a limited understanding of subsurface data in southwestern- and southeastern-most Alberta. In this study outcrop exposures throughout southern Alberta are tied to reference well logs and subsurface cross-sections allowing a more precise understanding of BRG architecture and how it relates to well-known vertebrate fossil producing areas. Modifications to an existing stratigraphic model of the BRG show that the Oldman and the Dinosaur Park formations have reciprocal north-to-south wedge-shaped geometries and a diachronous contact that become prominently expressed south of Twp 12. The updated model also demonstrates that the Oldman Formation thickens stratigraphically up-section to the south, and that the Foremost-Oldman contact is, essentially, a datum across much of southern Alberta. Identification of the Oldman Formation in the subsurface remains based on its relatively high gamma-ray response in mudstone successions, but it is also recognized that many of its sandstones exhibit relatively low gamma-ray responses like those in underlying and overlying formations. Nomenclature and subdivisions of the Oldman Formation are revised to accommodate this updated understanding, and modifications are also made to the definition of the Judith River-Belly River discontinuity, a newly recognized surface that marks the onset of accommodation and eustatic rise in sea-level in the northern Western Interior Basin at ~76.3 Ma.

An investigation of the state changes of PSR J2021+4026 and the Vela pulsar

ABSTRACT We report on long-term evolution of gamma-ray flux and spin-down rate of two bright gamma-ray pulsars, PSR J2021+4026 and Vela (PSR J0835−4510). PSR J2021+4026 shows repeated state changes in gamma-ray flux and spin-down rate. We report two new state changes, a first one from a low gamma-ray flux to a high flux that occurred around MJD 58910, and a second one from high to low flux that occurred around MJD 59510. We find that the flux changes associated with these two state changes are smaller than those determined in the previous events, and the waiting time of the new state change from the high gamma-ray flux to low gamma-ray flux is significantly shorter than previous events. Since the waiting time-scale of the quasi-periodic state changes of PSR J2021+4026 is similar to the waiting time-scale of the glitch events of the Vela pulsar, we search for the state change of the gamma-ray emission of the Vela pulsar to investigate the possibility that the glitching process is the trigger of the state change of PSR J2021+4026. For the Vela pulsar, the flux of the radio pulses briefly decreased around the 2016 glitch, suggesting that the glitch may have affected the structure of the magnetosphere. Nevertheless, we could not find any significant change of the gamma-ray emission properties using 15 yr of Fermi-LAT data. Overall, it seems inconclusive that a glitch-like process similar to that occurred to the Vela pulsar triggers the structure change of the global magnetosphere and causes state changes of PSR J2021+4026. Further and deep investigations to clarify the mechanism of the mode change for PSR J2021+4026 are required.

Soil-to-organic Sangyod rice grain transfer factors (TF values) of natural and anthropogenic radionuclides in Phatthalung province, Thailand

The specific activities of natural (40K 226Ra and 232Th) and anthropogenic (137Cs) radionuclides in paddy soil and organic Sangyod rice grain were measured and analyzed in this study with an aim to determine the soil-to-organic Sangyod rice grain transfer factors (TF values) of all required radionuclides in Don Pradu sub-district, Pak Phayun district in Phatthalung province in the south of Thailand. The high purity germanium (HPGe) detector and gamma-ray spectrometry analysis system which were installed and used in advanced laboratory at TINT were used to conduct experiments to measure and analyze of all required radionuclides in this research. The average concentrations of 40K 226Ra, 232Th, and 137Cs in paddy soil were found to have a value of 657.30 ± 23.03, 180.01 ± 4.39, 162.02 ± 3.84 and < 1.81 Bq/kg respectively while in organic Sangyod rice grain, their values were 24.11 ± 2.01, 0.28 ± 0.07, 0.17 ± 0.06 and 0.10 ± 0.03 Bq/kg respectively. For TF values were calculated and found to be 0.037, 0.002, 0.001, and 0.055 for 40K, 226Ra, 232Th, and 137Cs, respectively. Furthermore, four important radiological hazard indices which are gamma-absorbed dose rate (D), radium equivalent activity (Raeq), external hazard index (Hex) and annual external effective dose rate (AEDout) were also evaluated by using the average values of 40K, 226Ra and 232Th. In addition, by using the AEDout value, the excess lifetime cancer risk (ELCR (outdoor)) in paddy soil in the study area would be also studied, evaluated and presented. Moreover, the evaluated TF values of required radionuclides were higher than that reported by the International Atomic Energy Agency (IAEA) in 2010 but the values were much lower than those in the study in Malaysia.

Outstanding effect of cost-saving heavy nano-ferrites on the physico-mechanical properties, morphology, and gamma radiation shielding of hardened cement pastes

The purpose of this study is to synthesize heavy nano-ferrites (e.g. nano-CaFe2O4 and nano-CuFe2O4) using facile and economical sol–gel method to investigate their effect on the physico-mechanical, morphological, and gamma radiation shielding of hardened cement pastes. After the synthesis process, the nano-ferrites were characterized using transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive X-ray (SEM/EDX), X-ray diffraction (XRD) and particle size distribution analyses and then admixed to ordinary Portland cement (OPC) with different doses (e.g., 0, 0.25, 0.5, 1, and 2 mass%). The physico-mechanical characteristics of the cement pastes containing different ratios of heavy nano-materials were investigated at various hydration times. SEM/EDX and FTIR techniques were employed in addition to TGA/DTG to describe the microstructure and phase composition of the different hardened pastes. Gamma linear attenuation coefficients for Cs137 (662 keV) and Co60 (1173 and 1332 keV), as well as the most essential gamma transmission characteristics (half-value layer, HVL; tenth-value layer, TVL; and mean free path, MFP), were determined for selected pastes. The results revealed that the EDX spectrum of nano-CaFe2O4 clarifies that the Fe, Ca, and O elements are clearly observed at their corresponding keV values. Moreover, EDX spectrum of nano-CuFe2O4 properly reveals the presence of Cu, Fe, and O elements. These results confirm that the obtained product was of high purity. In addition, TEM photos indicate that the particle size of nano-CaFe2O4 is in the range of 7–22 nm, while the particle size range of nano-CuFe2O4 is 8–27 nm. It was found that the cement pastes containing 1% nano-CaFe2O4 and 1% nano-CuFe2O4 were the pastes that improved the physico-mechanical properties and high gamma ray shielding properties compared to the other prepared pastes. These nano-materials have high efficiency and economic feasibility.

An automated and robotic complex based on a xenon gamma-ray spectrometer for performing tasks for decommissioning nuclear and radiation hazardous facilities and monitoring the development of radioactive waste

The article focuses on a robotic gamma-ray spectrometric complex designed for decommissioning nuclear and radiation-hazardous objects and monitoring radioactive waste. The complex includes various components, such as radiation monitoring and regular observations to determine the object’s radiation parameters. The control of nuclear and radiation-hazardous objects performed using a High Pressure Xenon gamma-ray spectrometer that installed on a remotely controlled platform.