Gas-flow Proportional Counter Research Articles

GROSS ALPHA/BETA ACTIVITY DETERMINATIONIN DRINKING WATER PROFICIENCY TESTS

Water intended for drinking purposes has to be analyzed first for gross alpha/beta activity according to national and international standards and recommendations. According to Albanian legislation, Article 6, the gross alpha/beta radioactivity concentration in water, should be below the level of 0.1 Bq/L and 1 Bq/L respectively for human consumption. Our laboratory participated in an interlaboratory comparison organized by IAEA Terrestrial Environmental Laboratory under suggestion of ALMERA members. Proficiency Test among environmental radioactivity monitoring laboratories for the determination of gross alpha/beta activity concentration in drinking water and contaminated surfaces (2018, 2020). Independent standard methods were used for the reference value determination. Each sample was pretreated on site with nitric acid until reaching a pH level below 2. By creating relatively non-polar surfaces, this procedure avoids a loss of radionuclide fractions due to absorption into the walls of the containers.The Gross alpha/beta activity measurements were done using gas-flow proportional counter (GPC) method. The total dissolved solids should not exceed a surface density of 5 mg/cm2 for gross alpha determination and 10 mg/cm2 for gross beta determination The performance of participating laboratories was evaluated with respect to the reference values using relative deviations. The results presented from our laboratory in both inter comparisons (IAEA-TEL-2018-03) and (IAEA-TEL-2020-03) were all acceptable. The laboratory for the measurement of gross alpha/beta radioactivity and our Institute as a part of Tirana University is in the process of accreditation, so far the participation in the inter comparisons exercise is very important.

Three-dimensional surface analysis of iron-based materials using synchrotron Mössbauer source

A novel three-dimensional surface analysis system for iron-based solid materials has been developed. This system is composed of a synchrotron Mössbauer source, an X-ray focusing device, a precision stage, a gas flow proportional counter for conversion electron measurements, and multiple multichannel scalers. The performance was evidenced by determining the spatial distribution of the iron oxide abundance on a laser-ablated iron foil surface. This system can be widely utilized as a powerful analytical tool in steel science for corrosion, welding, and laser surface modification.

Assessment of radiological hazards of soils from the city of Bitola (Macedonia) and its environs

ABSTRACT To establish the radioactivity level of soils and assess the associated radiological impact on residents, 58 samples from the town of Bitola and its environs were collected. After conducting gross alpha and gross beta measurements with a gas-flow proportional counter as a preliminary screening test, subsequent gamma-spectrometry measurements reveal the presence of 40K, 226Ra, 232Th, and 137Cs in the soil samples as radionuclides with the highest impact. The absorbed gamma dose rate, the annual effective dose, radium equivalent activity, external hazard index, gamma index, excess lifetime cancer risk, and annual gonadal dose were calculated using the obtained activity concentrations of the radionuclides. Upon comparison with similar studies conducted in the Balkan countries, the obtained results for radiation hazard indices were found to be the highest in the region. Coloured maps were generated to visually represent the spatial distribution of the absorbed gamma dose rate in air and annual effective dose, clearly indicating the combined influence of geology and human activities, including the nearby thermoelectric power plant operation.

Distribution of some natural and artificial radionuclides in soil from the city of Bitola (Macedonia) and its environs.

The aim of the study is a thorough investigation of the radioactivity level in soils of the town of Bitola (Macedonia) and its environs. Topsoil samples collected from 58 locations within a 5×5 km grid were analysed. Serving as a screening, gross alpha and beta activity measurements were performed using gas-flow proportional counter. Gamma-spectrometric measurements revealed the presence of three natural (40K, 226Ra, 232Th) and one artificial radionuclide (137Cs) in the samples. The activity concentrations of these radionuclides were consistent with the results of similar studies in neighbouring areas. Spatial distribution maps and factor analyses have revealed that the activity concentrations of the natural radionuclides are strongly influenced by geology and have no significant influence from human activities. A correlation of 137Cs activity concentrations with terrain elevation was also observed. The aim of the study is a thorough investigation of the radioactivity level in soils of the town of Bitola (Macedonia) and its environs. Topsoil samples collected from 58 locations within a 5×5 km grid were analysed. Serving as a screening, gross alpha and beta activity measurements were performed using gas-flow proportional counter. Gamma-spectrometric measurements revealed the presence of three natural (40K, 226Ra, 232Th) and one artificial radionuclide (137Cs) in the samples. The activity concentrations of these radionuclides were consistent with the results of similar studies in neighbouring areas. Spatial distribution maps and factor analyses have revealed that the activity concentrations of the natural radionuclides are strongly influenced by geology and have no significant influence from human activities. A correlation of 137Cs activity concentrations with terrain elevation was also observed.

A new method for quantifying 64Cu in nuclear debris samples

Quantifying 64Cu in post-detonation nuclear debris samples can provide important diagnostic information regarding the structural materials used within a nuclear device. However, this task is challenging due to the weak gamma emissions associated with the decay of 64Cu, its short half-life (12.701 h), and the presence of interfering fission product radioisotopes. Large quantities of debris sample are generally needed to accurately quantify 64Cu, which can be problematic in sample-limited scenarios where other radiometric analyses are required. Herein, we present a new method for the separation of 64Cu from solutions of mixed fission products and demonstrate the quantification of its activity through use of gas-flow proportional beta counting. The new method was validated through a series of rigorous tests and was shown to improve the detection limit of 64Cu by over two orders of magnitude, from 2.5 × 106 to 1.3 × 104 atoms/sample for 100 min measurements.

Characterization of 235U, 238U and 239Pu fission ionization chamber foils by [formula omitted] and [formula omitted]-ray spectrometry

The masses of thin, electroplated deposits of 235U, 238U and 239Pu on titanium backings have been determined to better than 1.3% precision by employing three complementary measurement techniques: α spectrometry, 2π gas counting, and γ-ray spectrometry. A dedicated α spectrometer was designed and calibrated to allow for repeatable, high-precision measurements of the absolute α activity of a sample. The isotopic composition of the sample was determined by fitting the peaks in the α spectrum, a technique which was demonstrated to be generally consistent with mass spectrometry. Independently, the total activity of the deposits were measured in a 2π gas flow proportional counter. A detailed study of the effects of α particle straggling in the actinide deposit and α particle recoil off the sample backing material was performed. The masses of these actinide deposits were also measured via γ-ray spectrometry. We found that all three systematically independent techniques produced consistent results, and could be combined into a weighted average with further reduced uncertainty. The mass ratios of these actinide deposits were determined to better than 1% precision via α spectrometry, enabling high-precision fission cross section ratio measurements.

Alternatives to NIST Cf-252 Iirradiations for Transfer Calibration of S-32 Neutron Monitors

Gas-flow proportional counting systems are used by the Radiation Metrology Laboratory (RML) at Sandia National Laboratories for reactor fluence monitoring with the 32S(n,p)32P reaction. Calibration of these systems has traditionally been accomplished by fluence-transfer irradiations at the NIST 252Cf facility. Such calibrations have become increasingly difficult as the NIST 252Cf source decayed to unusable levels. To minimize the risk to the testing programs from an inability to properly calibrate these systems, the RML has developed two alternative calibration techniques: 1) development and implementation of certified 32P sources for activity calibrations and subsequent calculation of neutron fluence, and 2) direct counting of non-certified reactor-irradiated sulfur pellets by liquid scintillation counting to determine 32P activity for the subsequent calibration of gas-flow proportional counters. Preliminary comparisons show that the several calibration methods are capable of overall uncertainties within about 5 percent.

Risk assessment of ionizing radiation and radiological thresholds to compound an environmental baseline for the unconventional gas industry.

The exploration of unconventional hydrocarbons may be very effective in promoting economic development and confronting energy crisis around the world. However, the environmental risks associated with this practice might be an impediment if not adequately dimensioned. In this context, naturally occurring radioactive materials and ionizing radiation are sensitive aspects in the unconventional gas industry that may compromise the environmental sustainability of gas production and they should be properly monitored. This paper provides a radioecological assessment of the São Francisco Basin (Brazil) as part of an environmental baseline evaluation regarding the Brazilian potential for exploring its unconventional gas reserves. Eleven and thirteen samples of surface waters and groundwater were analyzed for gross alpha and beta using a gas flow proportional counter. A radiological background range was proposed using the ± 2 Median Absolute Deviation method. Using geoprocessing tools, the annual equivalent doses and lifetime cancer risk indexes were spatialized. Gross alpha and beta background thresholds in surface water ranged from 0.04-0.40Bq L-1 to 0.17-0.46Bq L-, respectively. Groundwater radiological background varies from 0.006-0.81Bq L-1 to 0.06-0.72Bq L-1 for gross alpha and beta, respectively. All environmental indexes are relatively higher in the south of the basin, probably a direct response to the local volcanic formations. Traçadal fault and local gas seepages might also influence the gross alpha and beta distribution. All samples have radiological indexes below the environmental thresholds, and should remain at acceptable levels with the development of the unconventional gas industry in Brazil.

Measuring the soft x-ray quantum efficiency of a hybrid CMOS detector

Next-generation X-ray observatories, such as the Lynx X-ray Observatory Mission Concept or other similar concepts in the coming decade, will require detectors with high quantum efficiency (QE) across the soft X-ray band to observe the faint objects that drive their mission science objectives. Hybrid CMOS Detectors (HCDs), a form of active-pixel sensor, are promising candidates for use on these missions because of their fast read-out, low power consumption, and intrinsic radiation hardness. In this work, we present QE measurements of a Teledyne H2RG HCD, performed using a gas-flow proportional counter as a reference detector. We find that this detector achieves high QE across the soft X-ray band, with an effective QE of $94.6 \pm 1.1 \%$ at the Mn K$\alpha$/K$\beta$ energies (5.90/6.49 keV), $98.3 \pm 1.9 \%$ at the Al K$\alpha$ energy (1.49 keV), $85.6 \pm 2.8 \%$ at the O K$\alpha$ energy (0.52 keV), and $61.3 \pm 1.1 \%$ at the C K$\alpha$ energy (0.28 keV). These values are in good agreement with our model, based on the absorption of detector layers. We find similar results in a more restrictive analysis considering only high-quality events, with only somewhat reduced QE at lower energies.

Evaluation of Gross Alpha and Beta Radioactivity Concentrations in Tooth Samples

Objective: Teeth are used as an important data source to estimate radioactivity accumulation in individuals. This study aimed to evaluation the gross alpha (GA) and gross beta (GB) radioactivity concentrations in tooth samples.Methods: Mandibular permanent first molar teeth of individuals living in the Middle Black Sea region were used for the study to ensure standardization. The teeth samples were divided into 4 groups according to the age factor (Group 1: 6-15 years, Group 2: 16-30 years, Group 3: 31-45 years, and Group 4: 46-65 years). Each group was divided into two subgroups according to gender factor. Measurements were completed with a nuclear spectroscopic system containing a gas-flow proportional counter. Data were analyzed statistically.Results: While a statistically significant difference was detected among groups for GA radioactivity concentration (p<0.05), no significant difference was detected among groups for GB (p>0.05). Mean GA value was higher in Group 1 (6-15 years) compared to the other groups. There was no statistically significant difference between the genders in both GA and GB radioactivity concentrations for all groups (p>0.05).Conclusion: While the GA radioactivity concentration was affected by the age factor, it was not affected by the gender factor.

Evaluation of Gross Alpha and Beta Activity Concentrations and Annual Effective Dose in Drinking Waters of Misan Province-Iraq Using Low Background Gas Flow Proportional Counter (LB- 4110)

In this study, assessment of levels natural radioactivity in drinking water samples of Misan Province of Iraq was carried out. A total of 33 (Tigris river, station and Tap) water samples collected from eleven places in Misan Province of Iraq. The beta and alpha gross radioactivity of the samples water was measured and an average annual effective dose derived of drinking-water ingestion was estimation utilizing new model a LB-4110 low background gas flow proportional counter. The data indicated that the Beta and Alpha gross activities and annual effective dose in samples did not exceed WHO recommended levels (0.5 Bq/L of Alpha gross, 1.0 Bq/L of Beta gross and 0.1 mSv/y for annual effective dose).

Evaluation of Gross Alpha and Gross Beta Radioactivity in Crude Oil Polluted Soil, Sediment and Water in the Niger Delta Region of Nigeria

The evaluation of gross alpha and beta activities in crude oil contaminated soil, sediment and water samples was conducted in ten oil polluted environment of Delta State using Gas-flow proportional counter. Samples were collected from the oil polluted environment in each oil field and samples were prepared and analyzed following standard procedures. The mean gross alpha and beta activities obtained are 331.4 ± 24.5 Bq kg-1 and 11,335 ± 112 Bq kg-1 respectively for soil, 259.2 ± 17.6 Bq kg-1 and 4508 ± 96 Bq kg-1 respectively for sediment, and 1.00 ± 0.09 Bq kg-1 and 20.3 ± 1.7 Bq kg-1 respectively for water. The estimated average values of the total annual effective dose equivalent (AEDET (α,β)), the total annual gonadal dose equivalent (AGDET (α,β))), and the total excess lifetime cancer risk (ELCRT (α,β)) are 10.64 mSv y-1, 0.037 μSv y-1 and 0.037 μSv y-1 respectively. The gross alpha and beta activities values obtained in soil and sediment were relatively high compared to values reported in some parts of the country and other regions and countries of the world. The radiological risk parameters examined show that AEDET (α,β) and AGDET (α,β) are above recommended permissible limits while ELCRT (α,β) is within the recommended permissible limit. The overall results obtained in this study indicate that the environmental samples have been radiologically impaired due to the crude oil spillage. An appropriate remediation technique was therefore recommended to remediate the polluted soil, sediment, and water to their near original state.

Improved sample preparation procedure for gross alpha counting on gas-flow proportional counter

Sample residue uniformity is crucial for accurate gross alpha counting using a gas-flow proportional counter, however this can be difficult to achieve using conventional procedures. An evaporation method using a 1:1 mixture of deionized water and 2-propanol yielded uniform 230Th and 241Am nitrate salt residues on metal planchets for gross alpha counting. The gross alpha efficiency and alpha:beta crosstalk behavior were studied using the evaporation procedure and a separate barium sulfate/ferric hydroxide coprecipitation method. The gross alpha efficiency data were fitted with empirical power law functions. The alpha:beta crosstalk behavior was different for the two radionuclides studied.

Primary standardization and determination of gamma ray emission intensities of Ho-166

The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN-CNEN/SP, in São Paulo, for the primary standardization of 166Ho is described. The activity of 166Ho was determined by the efficiency extrapolation technique applied to a 4πβ(PC)-γ coincidence system using a gas flow proportional counter in 4π geometry coupled to a 76 × 76 mm NaI(Tl) crystal. The results for the γ-rays intensities at 80.57 and 1379.45 keV were 0.0651(11) and 0.00904(11), respectively.

Historical inputs of polycyclic aromatic hydrocarbons in the preserved tropical estuary of the Itapicuru River, Bahia, Brazil

The aim of present study was to evaluate temporal changes in the distribution of polycyclic aromatic hydrocarbons (PAHs) in the estuary of the Itapicuru (Brazil). A sediment core was sampled in the study area. Concentrations of the 16 priority PAHs were analyzed using gas chromatography coupled to a mass spectrometry. A gas flow proportional counter was used to estimate the sedimentation rate through the determination of 210Pb. Granulometric fractions and total organic carbon (TOC) concentrations were also evaluated. Concentrations of TOC and PAHs ranged from 0.65 to 2.51% and 1.98 to 43.1 ng g−1 (dry weight), respectively. Significant correlations (p < .05) were found between the mud content in the sediment core samples and concentrations of both TOC and PAHs. Higher PAH concentrations occurred after the 1950s. The main sources of PAHs over time were local human activities on the northern coast of the state of Bahia.

Screening Level of Gross Alpha and Beta Activities in Building Materials

The objective of the present study is the screening of the gross alpha and gross beta activity of some building materials commercialized in Saudi Arabia. The measurements were carried out using a gas flow proportional counter. The study has shown that the gross alpha activity ranged between 0.21 and 8.27 Bq/kg with an average activity of about 1.96 Bq/kg, whereas the gross beta activity ranged between 6.47 and 276.47 Bq/kg with an average activity of about 65.27 Bq/kg. The obtained values of gross alpha and beta activities are in the worldwide range and no significant activity was observed that accentuate the attention, which show that no radiation risks come from these building materials and, therefore, from their origin areas.

Simultaneous Determination of Gross Alpha/Beta Activities in Groundwater for Ingestion Effective Dose and its Associated Public Health Risk Prevention

This paper presents information on the gross alpha and gross beta activity concentrations of two hundred twenty-six groundwater samples collected by gas flow proportional counters in southern Vietnam. The gross alpha results in the water samples ranged from 0.024 to 0.748 Bq L−1 with a mean of 0.183 ± 0.034 Bq L−1, and the gross beta results in the water samples ranged from 0.027–0.632 Bq L−1 with a mean of 0.152 ± 0.015 Bq L−1. The values obtained in this work were compared with those previously published for various regions or countries. Next, untreated and treated groundwater samples were analyzed to assess their influences on the treatment process. The results showed that there were differences in the minimum detection concentrations and the mean activity values between the untreated and treated groundwater samples (The p-value of the mean comparison tests is significant with p < 0.05). In both sample groups, there was a strong positive correlation of the gross alpha versus the gross beta results (r > 0.6). This means that among the radionuclides, the major sources of beta radiation are uranium and thorium decay series radionuclides. Finally, the annual effective dose for adults (>17 years) was calculated based on the assumption that major radionuclides have the highest effective dose conversion factors. In general, the results for Pb-210, Ra-226, and Ra-228 were observed to be lower than the recommended reference values established by the World Health Organization and the International Atomic Energy Agency, except for the value of Po-210.

Accurate integral counting using multi-channel analyzers

Many techniques in radionuclide metrology rely on accurate measurement of the total count rate, that is integral counting, from a detector. We present the design and results from integral counting using a live-timed multi-channel analyzer (MCA) based on a list-mode digitizer and a live-timed scalar, both with imposed, extending dead times. These systems were benchmarked against an existing NIST anti-coincidence counting system. Both systems were used to determine correction factors to an MCA that uses Gedcke-Hale dead-time corrections. Tests were performed for a large-area gas-flow proportional counter and a NaI(Tl) detector for count rates up to 80 000 s−1. The results were used to create correction factors suitable for alpha- and beta-particle emission rate calibrations.

Tracking Hg historical inputs by Pb-210 geochronology for the Itapessoca Estuarine Complex, Pernambuco, Brazil

The application of geochronology for tracking mercury contamination was remarkably demonstrated in the Itamaraca Estuarine Ecosystem, Pernambuco State, Brazil. Here, two sediment cores were sampled, layered and analyzed by the Gas Flow Proportional Counter technique for determining 210Pb, radionuclide applied to geochronology. Mercury was quantified in sediment samples by Cold Vapor Atomic Absorption Spectrometry, varying from 0.17 to 1.29 mg kg−1 in deep sediments. From 210Pb results, the sedimentation rates of 0.84 (0.07) cm year−1 and 1.03 (0.22) cm year−1 confirmed Hg contamination in Itamaraca since mid-1965. Events of extreme precipitation and drought have been also related to the distribution pattern for Hg concentrations in deep sediments.

Characterization of an array of gas-flow proportional counters for determination of gross alpha and gross beta in drinking water

The performance of an array of gas proportional counters (Model LB4200TM) was characterized for assessing gross radioactivity in drinking water. Among others, the examined parameters included detection efficiency and minimal detectable activity concentration. The study of the system parameters was conducted using water samples with known activities of 230Th and 90Sr and known salinity levels that were prepared according to the co-precipitation and evaporation methods. The detection efficiencies for alpha and beta in water samples were found to be 16% and 37%, respectively. In addition, the extraction efficiencies of radionuclides in water samples using the co-precipitation and evaporation methods were found to be approximately 90%. Minimal detectable concentrations for gross alpha and gross beta were found to be typically 0.02 Bq/L and 0.13 Bq/L, respectively. Results demonstrate that although the system detectors as well as the prepared water samples have relatively small diameters (40–49 mm), the system and methods used meet the criteria for determining gross alpha and gross beta in drinking water.