High-resolution Gamma-ray Spectrometry Research Articles

A baseline of natural radionuclides in water and sediment of a pristine coastal ecosystem: The Xcalak and Mahahual coral reef lagoons in the western Caribbean

In ecosystems, natural radionuclides are present in the environment and living organisms. The 238U natural decay chain produces multiple radioactive elements, such as 234U, 226Ra, 210Pb, and 210Po. These radionuclides can be found in air, water, rocks, soil, and other biotic and abiotic components, mainly derived from minerals, such as zircon and apatite. In this study, we determined the activity concentration of radionuclides from the 238U decay chain in the sediment of a coastal ecosystem on the southern Mexican coast in the western Caribbean, an ecosystem minimally affected by industrial activities. Methods included high-resolution gamma-ray spectrometry and alpha-particle spectrometry. Results showed that the sediment samples had an activity concentration range of 18.2–36.6 Bq/kg for 238U, 25.0–41.4 Bq/kg for 234U, 10.1–37.3 Bq/kg for 210Pb, and 29.9–46.0 Bq/kg for 210Po. Water samples ranged between 17.9 and 36.3 mBq/L and 27.9–66.0 mBq/L for 238U and 234U, respectively. The activity concentration of these radionuclides in the sediment and water of this area is compared with that of other coral reefs worldwide, providing a radiometric baseline for comparison purposes.

Decommissioning of a Medical Cyclotron Vault: the Case Study of the National Cancer Institute of Milano.

In the widespread use of medical cyclotrons for isotope production, radiological and economic consequences related to the decommissioning of particle accelerators are often neglected. However, decommissioning regulation and its related procedures always demand efforts and costs that can unexpectedly impact on budgets. The magnitude of this impact depends strongly on the residual radioactivity of the accelerator and of the vault, and more specifically on the kind and activity concentration of residual radionuclides. This work reports and discusses a case study that analyzes in detail the characterization activities needed for optimized management of the decommissioning of a medical cyclotron vault. In particular, this paper presents the activities carried out for assessing the activity concentrations and for guiding the disposal of the cyclotron vault of the Italian National Cancer Institute of Milano (INT). An unshielded 17 MeV cyclotron vault was characterized by high resolution gamma-ray spectrometry both in-situ and in-laboratory on extracted samples. Monte Carlo simulations were also carried out to assess the overall distribution of activation in the vault. After a few months from the final shutdown of the accelerator, activity concentrations in the concrete walls due to neutron activation exceeded the clearance levels in many regions, especially close to the cyclotron target. Due to the relatively long half-lives of some radionuclides, a time interval of about 20 y after the end of bombardment is necessary for achieving clearance in some critical positions. Far from the target or in positions shielded by the cyclotron, activation levels were below the clearance level. The comparison between Monte Carlo simulations and experimental results shows a good agreement. The in-situ measurements, simpler and economically advantageous, cannot completely replace the destructive measurements, but they may limit the number of required samples and consequently the decommissioning costs. The methodology described and the results obtained demonstrated that it is possible to obtain accurate estimations of activity concentrations with cheap and quick in-situ measurements if the concentration profile in-depth inside the wall is well known. This profile can be obtained either experimentally or numerically through suitably validated Monte Carlo simulations.

High resolution gamma-ray spectrometry for routine measurements of environmental samples

A practical and comprehensive experimental approach for radioactivity measurements of voluminous environmental samples using high-resolution gamma-ray spectrometry with High Purity Germanium (HPGe) detector is presented. The radioanalytical procedure includes sample preparation, detector calibration, implemented corrections, quality control and assurance; and it is demonstrated with the determination of natural and anthropogenic radionuclides in water and soil standard samples. The methodology is verified, and the results are validated by intercomparison with the refence values provided as part of a worldwide proficiency test.

Precision measurements of U3O8 and Ra(eU3O8) in uraniferous samples by gamma ray spectrometry using two HPGe coaxial P-type detectors (GCD30180 & GC5019 models)-a comparative study.

The precision measurements of U3O8 and Ra(eU3O8) concentrations were evaluated in 23 geological rock samples by high resolution gamma ray spectrometry (HPGe) using two P-type HPGe detectors. The use of Detector 2 (DET2) (GC5019) has increased the sensitivity by a factor of two for both the measurements in comparison to Detector 1 (DET1) (GCD30180). The Minimum Detection Limit (MDL) and Limit of quantification (LOQ) for U3O8 in DET2 has increased significantly because of negligible background counts in 1.001MeV ϒ energy peak (0.838% gamma yield). The MDL for Ra(eU3O8) measured by 0.609MeV and 1.760MeV has not improved significantly due to the high background counts in these energies whereas LOQ has improved appreciably. DET 2 has given higher level of confidence in reporting the analytical results with acceptable repeatability due to the decrease in uncertainty of the measurements.

Gamma-radiation levels along the main Karakorum thrust area of Northern Pakistan

Abstract In this contribution, the distribution of naturally occurring radionuclides in the area around Main Karakoram Thrust (MKT) in Karakoram Range, North Pakistan is documented. Three natural radionuclides (226Ra, 232Th, and 40K) and one anthropogenic radionuclide (137Cs) were studied for their specific activities in 30 samples. The measurements were made by high resolution gamma-ray spectrometry. The sampling area is located in Gilgit Baltistan province of Pakistan at an altitude of 1838 m/6030 ft above sea level. MKT separates the Karakoram plate from the Kohistan-Ladakh Terranes and Indian Plate to the south. The specific activity varied as 4.5–56.5 Bq kg−1, 18.2–61.4 Bq kg−1, 1.4–19.6 Bq kg−1 and 51–1640 Bq kg−1 for 226Ra, 232Th, 137Cs and 40K, respectively. The average radium equivalent activity was 127.8 ± 45.9 Bq kg−1. The external hazard index was <1 for all samples and representative level index was <1 for majority of the samples. The average air absorbed dose rate was 60.9 ± 23.2 nGy h−1 corresponding to the outdoor effective dose rate of 73.7 ± 28.0 μSv y−1. These values were slightly higher than the world average values for air absorbed dose rate (51 nGy h−1) and outdoor annual effective dose rate (70 μSv y−1). The data revealed significant positive correlation between 226Ra and 40K. Principal component analysis revealed distribution patterns within the samples and identified three distinct groups. Data was also evaluated for the concentrations of uranium, thorium and potassium and their ratios.

Application of High-Resolution Aeromagnetic and Gamma-ray Spectrometry Surveys for Litho-Structural Mapping in Southwest China

Airborne geophysical surveys serve as an effective tool for litho-structural mapping, providing extensive and high-resolution underground information. They offer vital data support for the interpretation and analysis of lithologies and structures, complementing surface geological mapping. In the study area of the Nanpanjiang-Youjiang metallogenic belt in southeast China, we obtained high-resolution aeromagnetic and gamma-ray spectrometry data covering an area of approximately 27,000 km2, which facilitated the conduct of litho-structural mapping. The total magnetic intensity, reduction to the pole, and directional derivative maps generated from the aeromagnetic data, efficiently identified concealed rocks and faults. Additionally, the total count, potassium, thorium to potassium ratio, and ternary maps generated from the airborne gamma-ray spectrometry data demonstrated advantages in distinguishing carbonate rocks from clastic rocks. They also provided more comprehensive geological information, refining the structural strike and location interpreted by the aeromagnetic data. The litho-structural map produced in this study significantly contributes to our understanding of the structures in the Nanpanjiang area and offers valuable guidance for successful mineral exploration endeavors.

Measurements of some radionuclides in coffee samples using gamma-ray spectrometry and evaluating radiological health risk to the Turkish public

ABSTRACT The current research aims to assess the radioactivity levels and radiological health risks of 28 coffee samples from 21 assorted brands obtained from different provinces of Turkey. The activity concentrations of natural radionuclides (226Ra, 232Th and 40K) and artificial radionuclide 137Cs in the samples were quantified using the high-resolution gamma ray spectroscopy technique with an HPGe detector. 137Cs could not be found in any of the samples. The activity concentrations in all coffee samples were found in the range of <MDA–2.93 Bq kg−1 with an average of 1.24 Bq kg−1 for 226Ra, <MDA–3.06 Bq kg−1 with an average of 1.51 Bq kg−1 for 232Th and 433.67–538.69 Bq kg−1 with an average of 496.24 Bq kg−1 for 40K. Radiological parameters such as annual intake of radioactivity (Yint), committed effective dose (Deff), threshold consumption rate (DIthresh), and excess lifetime cancer risk (ELCR) were evaluated to estimate human radiological risk in the coffee samples. The total committed effective dose to an individual due to the consumption of each coffee sample was less than the dose limit of 290 μSv y−1 suggested by UNSCEAR. The lowest threshold consumption rate (kg y−1 or g d−1) calculated in all coffee samples was higher than the amount of coffee consumed per year (kg y−1) and the amount of coffee consumed at the daily normal level (g d−1, cups d−1). The total lifetime cancer risks from ingestion of the sampled coffees were estimated to be less than the advised safety limit (10−3). Based on the obtained results, none of the coffee samples analysed in the present study constitute a possible radiological risk for public health. Pearson’s correlation coefficient analysis (PCCA) and discriminant analysis (DA) were used to present the relationships between the radionuclides and distinguish the group members, respectively.

Cleaner, sustainable, and safer: Green potential of alkali-activated materials in current building industry, radiological good practice, and a few tips

Alkali-activated materials were prepared from four typical precursors (coal fly ash, granulated blast furnace slag, metakaolin, and brick waste powder) characterized for granulometry, elemental composition, and microstructure. High-resolution gamma-ray spectrometry was used to determine the activity concentration of Naturally Occurring Radioactive Materials (NORM) in all the materials to assess their radiological impact. All the investigated materials have been found to comply with the European dosimetric index (I) according to Directive 2013/59/Euratom. The results suggest the need for an accurate check of radioactivity throughout the mixing phases to prevent I exceedances. The productive chains were also evaluated by principal component analysis.

Investigation of 252Cf sources with a Ge gamma-ray detector.

This study investigated the feasibility of combining high-resolution gamma-ray spectroscopy with the simulation capabilities of the Nucleonica Nuclear Science Portal with the aim to determine the properties of Cf sources. In this contribution, we present the results for a 20-month-old and a 49-year-old Cf source. In particular, the question arises whether the neutron emission rate can be determined using gamma-ray spectroscopy.

Metallic Bhasmas: A Review on Chemical Characterization, Particle Size and Toxicity

Bhasmas are unique metallic-herbal preparations of Indian origin, widely recommended for the treatment of chronic ailments. These intriguing formulations of metals are associated with organic macromolecules derived from the medicinal herbs. Bhasmas are often prepared by repeated incineration of metals with herbs and its extracts by alchemic processes and are taken along with honey, milk, butter, or ghee. Besides primary constituent of metals, bhasmas also contain other metals as minor constituent or in traces. Commercially available seventeen bhasmas based on Ca, Fe, Zn, Hg, Cu, As, Ag and Sn were characterized by instrumental neutron activation analysis (INAA) for up to 20 elements. The technique involves irradiation of the sample with thermal neutrons in a nuclear reactor followed by assay of gamma activity by high-resolution gamma ray spectrometry. Concentrations of major, minor, and trace elements vary in a wide range even in bhasmas of the same primary element depending on its preparation method. C, H, and S were also found in significant amounts suggesting the possible presence of organic macromolecules that may act as ligands. Transmission electron microscopy (TEM) studies have shown that the bhasmas as available in the market are not really nano particles contrary to claims of some literature reports. Westerners think bhasmas to be highly toxic especially those of As, Hg, and Pb, highly toxic elements. Still bhaasms of these elements are widely recommended. Clinical evidences suggest that the bhasmas taken in small doses are highly beneficial to the body system and do not cause any adverse effects. It is essential to follow quality control in the preparation of bhasmas. A review of our earlier work is also presented.

Fly Bioash Ameliorates Acid Luvisol and Increases Sunflower (Helianthus annuus L.) Yield in Field Conditions without Compromising the Risk of Radioactive Contamination

Fly bioash (FBA) as a by-product of biomass-fuelled facilities exhibits alkaline properties and is enriched with phytonutrients, thereby offering the potential to effectively ameliorate acidic and nutrient-deficient soils. However, concerns about health risks due to a potential FBA radioactive contamination are still not well studied, notably under field conditions. This study examined pH changes and concentrations of natural (238U, 232Th, 226Ra, 40K) and anthropogenic (137Cs) radionuclides after application of very alkaline (pH &gt; 12) FBA in: (i) highly acid (pHKCl = 4.1) Luvisol and (ii) sunflower (Helianthus annuus L.) seeds, grown in organic farming and rain-fed conditions. FBA (originated from a modern cogeneration, fuelled on certified deciduous forest wood chips) was applied at increasing doses; 0, 4.5, 8.6, 13, and 17.2 t/ha. After 54 months of application, FBA significantly increased soil pHKCl by up to 1.8 unit and the seed yield by 15%, compared with no amended Control, without compromising soil electrical conductivity (salinity). The activity concentrations (Ac) of all observed radionuclides, measured using high-resolution gamma-ray spectrometry, were not altered under FBA application, neither in the surface (0–30 cm) Luvisol horizon nor in the sunflower seed. Moreover, the Ac of 238U, 232Th, and 137Cs in the seed were below detection limit, whereas the Ac of 40K and 226Ra were lower by up to 2.6 and 61 times, respectively, than their corresponding Ac in the soil treatments. The radiological footprint of FBA exhibited lower Ac for most of the observed radionuclides compared with both (i) Croatian non-arable topsoils (with reductions of 238U 3.6 times, 232Th 1.8 times, 226Ra 1.7 times, and 137Cs 1.5 times) and (ii) widely used mineral N/P/K fertilisers in conventional agroecosystems (with reductions of 238U 12.5 times; 226Ra 1.3 times, and 40K 2.4 times). Our findings provide evidence that the application of FBA as a soil conditioner does not pose radiological health or environmental risks, contributing to more sustainable agri-food production and circular bioeconomy. However, it is essential to conduct further studies to comprehensively investigate the effects of FBA application on soil and crop quality across diverse environmental conditions and extended spatiotemporal scales.

High resolution gamma-ray spectrometry logging applied in the interpretation of sedimentary processes and environments of the Itararé Group (Permo-Carboniferous), Paraná Basin, Santa Catarina state

Outcrop gamma-ray spectrometric logging in the upper strata of the Campo Mourão Formation and lower strata of the Taciba Formation were used to investigate: (i) the influence of lithological variation on gamma-ray patterns; (ii) its potential to discriminate and identify lithotypes; and (iii) sedimentary processes and related environments of these Permo-Carboniferous strata. The gamma-ray logs were subdivided into three gamma-ray units, according to the total count, concentrations and contents of K, eU and eTh. These gamma-ray units were associated to three depositional units: Glaciolacustrine system with thin-bedded turbidites in the Campo Mourão Formation; and two submarine fans systems (channels, overbanks and lobes) with thick-bedded turbidites systems in the Taciba Formation. Gamma-ray spectrometry allowed distinguishing 'common' shales from black shales, which are often similar in the faciological description in fieldwork. Likewise, carbonate levels were identified as a function of the decrease in gamma-ray concentrations in black shales of the Campo Mourão Formation. The relationship between the radiometric data and the grain size indicated that, in the field, the lithological heterogeneity has a great influence on the ability of the gamma-ray spectrometer to distinguish lithotypes. The eTh/K and eTh/eU ratios were used to infer sedimentary processes and related environments. Through the eTh/eU ratio, a reducing environment, responsible for the precipitation of authigenic uranium in low sedimentation rate deposicional system, was evidenced, discriminating depositional units from different environments.

Validation of efficiency transfer for high-density materials in HPGe spectrometry

Recycling and conventional reuse of lead materials and structures originating from controlled areas in nuclear facilities rely on historical knowledge and well selected characterization procedures. At the SCK•CEN, one of these procedures involves performing high-resolution gamma-ray spectrometry measurements on several cylindrical shaped test samples (50 mm diameter and approximately 5 mm thickness), obtained during the lead melting campaigns. The high density (11.3 g/cm³) of these samples is a challenge for radionuclide analysis by gamma-ray spectrometry since no such calibration sources nor reference materials are available. We used the efficiency transfer procedure, relying on regular standard sources available in our laboratory, to set up calibrations for this specific counting geometry. The method proves to be fit for purpose.

Activation cross sections of proton-induced reactions on natural platinum up to 30 MeV

Activation cross sections of proton-induced reactions on natural platinum were measured. The stacked-foil activation technique and high-resolution gamma-ray spectrometry were used. The production cross sections of 198, 196, 196m2, 195, 194, 193, 192, 191Au, 191Pt, and 192, 190Ir were determined up to 30 MeV. The experimental results were compared with previous experimental data and theoretical calculations in the TENDL-2019 library.

Ultra-low-level measurements of airborne fission products from the Fukushima Daiichi reactor accident using high volume collection systems at Savannah River National Laboratory

Ultra-low-level measurements of radionuclides in air have been conducted at the Savannah River National Laboratory (SRNL) to determine the atmospheric concentration of fission products released following the Fukushima Daiichi reactor accident on March 11, 2011. Air filter samples were acquired from two high-volume collection systems (a traditional filter-based system and an electrostatic precipitator-based system) to monitor airborne radionuclide concentrations in the period covering from 2 weeks to 3 years after the disaster. The world-wide spread of low-level concentrations of airborne fission products from the Fukushima event provided a unique opportunity to demonstrate SRNL's electrostatic particle collection technology and other improvements in environmental monitoring developed at the Savannah River Site (SRS). Detecting and analyzing the release allowed a comprehensive test of SRS systems for monitoring environmental radioactivity. Gamma-ray-emitting fission products (131,132I, 134,136,137Cs, and 129,132Te) and cosmogenic isotopes (7Be and 22Na) in air were detected and quantified by high-resolution gamma-ray spectroscopy at concentrations as low as 0.07 μBq per standard cubic meter (SCM) (50 mBq total 137Cs), while plutonium content was quantified by thermal ionization mass spectrometry (TIMS) at concentrations as low as 6.5 × 10−21 g/SCM (3.0 fg 239+240Pu). Isotope concentrations measured at SRNL from gamma-ray spectroscopy were compared to independent measurements from Chapel Hill, NC, located approximately 370 km (230 mi) NE of SRNL. Meteorological modeling was also used to predict radionuclide transport from the location of release to both measurement locations.

The occurrence of 40K and 137Cs radioactivity in mosses during 2015-2019 in the Djerdap National Park (E. Serbia).

The radiation status of the national park (NP) Djerdap (Eastern Serbia) is characterized using bioindicators (mosses). Mosses (16 species, 156 samples) were collected randomly within the area of NP Djerdap during the month of June, periodically from 2015 to 2019. Samples were collected in the regions of Dobra, Donji Milanovac, and Tekija. Within the mosses, the presence of 40K and 137Cs is regarded as a good indicator of radionuclides present in the environment due to their easy interchangeability with 39K highly present in living moss organisms. The activity concentrations of gamma ray-emmiting radionuclides in samples were determined using high-resolution gamma ray spectrometry, an HPGe-ORTEC/Ametek detector. The determining activity concentrations of 40K and 137Cs in collected samples were as follows: for 40K from 31.4 to 721Bqkg-1and for 137Cs varied from 2.6 to 908Bqkg-1. The average activity concentrations of 40K and 137Cs (Bq kg-1) in mosses in the period 2015-2019 were the lowest in moss samples collected in the Dobra region, and the highest in the area of Donji Milanovac. The most prevalent collected moss species within the Djerdap National Park was Hypnum cupressiforme. The determined activity concentrations in H. cupressiforme of 137Cs for the whole region of NP Djerdap for all 5years was 78.1 ± 70.3Bqkg-1 and of 40K was 181 ± 86.1Bqkg-1.

Discrimination of phosgene from cyanogen chloride in recovered chemical munitions using tagged neutron interrogation with high-resolution gamma-ray spectroscopy

The associated particle (AP) technique has recently been used with a high-purity germanium γ-ray spectrometer to assess its capability to improve field identification of recovered chemical warfare (CW) materiel through prompt gamma-ray neutron activation analysis (PGNAA) measurements. A particularly challenging pair of CW agents commonly found in recovered munitions are phosgene (CG) and cyanogen chloride (CK), which have two of three elements in common, i.e. chlorine and carbon, but differ in the third being either oxygen or nitrogen. The detection of both latter elements is complicated by high oxygen concentration in the field environment which interferes with the small signal produced from the chemical agents. The matter is further complicated by the precautionary field practice of overpacking recovered munitions with vermiculite in larger steel multiple round containers (MRCs), which places additional oxygen-rich material in contact with the munition while further attenuating an already weak signal emitted from the munition center. This work reports quantitative results from realistic field measurements of CG and CK simulants in mock 4.2-inch (11 cm) mortar rounds overpacked with vermiculite in a large MRC. Results obtained with the AP technique are compared to those obtained with the traditional PGNAA approach for both overpacked- and bare-munition measurements. The AP technique is shown to provide a much more confident discrimination between the two chemicals, particularly for the more challenging field-relevant overpacked measurements, where a significant gain in sensitivity to all the key elements (chlorine, carbon, nitrogen and oxygen) is achieved.

Role of neutron attenuators for gamma-ray measurements in deuterium-tritium magnetic confinement plasmas.

The Joint European Torus (JET) is the only tokamak in the world able to operate in Deuterium-Tritium (DT) plasmas. A successful DT experimental campaign, the DTE2, has recently been carried out, providing unique opportunities for studying both physics and technological aspects. In particular, it allowed us to investigate and benchmark the solutions adopted to attenuate the significant 14MeV neutron flux, needed to enable high-resolution gamma-ray spectroscopy measurements on a tokamak. While in inertial confinement experiments, gamma-rays and neutrons are discriminated through time-of-flight techniques; in magnetic confinement experiments, the neutron attenuators are a key element to allow gamma-ray measurements in order to reestablish the 1 × 105 to 1 background to signal ratio. In this paper, the role of the reference neutron attenuators at JET, based on LiH, has been analyzed and described.

Study of activation cross sections of proton induced reactions on natBa and natCe near their threshold energy regions

Abstract Activation cross-sections of the nuclear reactions natBa(p,x)135,132gLa, 135mBa and natCe(p,x)142,139,138mPr, 141,139,137mCe have been measured experimentally at the MGC-20 cyclotron, Cairo, Egypt, from their respective threshold energies up to about 14.7 MeV. Stacked foil irradiation technique and high-resolution gamma-ray spectroscopy were used. A comparison between the experimental and theoretical data derived from the nuclear model codes EMPIRE and TALYS (in the form of the TENDL library) was performed. The agreement in the low-energy region is fairly good. Integral yields of the produced radioisotopes were estimated from the present cross-section data and the results are discussed in terms of their production possibilities.

Measuring of natural and artificial radioactivity in Al-Dakhiliya governorate, Sultanate of Oman

Soil and sand samples were collected from eight different locations in the Al-Dakhiliya governorate, Sultanate of Oman to determine and evaluate the natural and artificial radioactivity levels. The activity concentrations of radionuclides 137Cs, 226Ra, 40K, 235U and 228Ac were measured using high resolution gamma-ray spectroscopy detectors (HPGe detectors). In addition, radiation hazard indexes were evaluated in order to measure radioactive risk for human beings and the environment. The activity concentrations of 137Cs, 226Ra, 40K, 235U and 228Ac were found as 0.82 ± 0.04, 29.01 ± 1.37, 290.14 ±2.79, 5.88 ± 0.65 and 39.57 ± 3.85 Bq/Kg respectively. Radium-equivalent activity Raeq was obtained and varied in the range from 340 to 43 Bq/Kg with a mean value of 108.3 Bq/Kg. The study found that the gamma indexes, external indexes and internal indexes in most sites were less than 1, which indicates a low radioactive dose. The study concludes that seven sites contain relatively low radioactivity, whereas one site requires more investigation in future as the results show a sort of rise in the radioactivity rate on its samples.