HPGe Gamma-ray Spectrometer Research Articles

Radon exhalation and emanation assessments in the Transdanubian Central Mountain in Hungary

ObjectiveTo determine the radium-226 activity concentration, the massic radon exhalation rate and emanation factor of 55 soil samples from the Central Transdanubian Mountains in Hungary as well as possible radon exhalation hotspots in the sampling area were determined. Further indoor measurements are planned to investigate the possible exposure to radon of the inhabitants. MethodsThe radium-226 activity concentration measurements were carried out with a semiconductor HPGe gamma-ray spectrometer. The massic radon exhalation rate and emanation factor were determined by measuring the radon activity concentrations using the accumulation method with a system developed by our department based on an AlphaGUARD DF2000 portable radon monitor. ResultsThe activity concentrations of radium-226 were between (11.4 ​± ​2.5) and (118.2 ​± ​3.0) Bq/kg, while their average was 39.51 Bq/kg. The massic radon exhalation rates were between (1.02 ​± ​3.64) mBq⋅kg−1⋅h−1 and (275.63 ​± ​4.05) mBq⋅kg−1⋅h−1, while their average was 39.51 mBq⋅kg−1⋅h−1. Finally, the emanation factors were between (0.01 ​± ​0.04) and (0.80 ​± ​0.03) with an average of 0.30. ConclusionsIn our study, the results recorded from the bedrock at the sampling sites were analyzed. 9 samples were taken from sites comprised of limestone bedrock, moreover, the average radium-226 activity concentrations and massic radon exhalation rates at these sampling sites were higher than average. It was also concluded that although no regional correlation can be seen from the results, a possible smaller radon hotspot was identified from our measurements where further sampling will be carried out.

Radiation source terms analysis and classification of radioactive waste for the decommissioning of the first HWRR reactor in China.

Nuclear reactors will face the problem of decommissioning at the end of their operating life due to the high radioactivity of reactor components and environmental safety considerations. The Heavy Water Research Reactor (HWRR) is the first large-scale research reactor to be decommissioned in China. The second phase of HWRR decommissioning involves the main components in the reactor block, so the radiation source terms and the radioactive waste level need to be evaluated before demolition and disposal. Based on the operating history, three-dimensional geometry, materials, and other information of the HWRR, the activity of radionuclides in the main components of HWRR is calculated and analyzed, and the MCNP/ORIGEN coupling scheme is utilized for theoretical analysis. The theoretical results indicate that 14C, 54Mn, 55Fe, 60Co, 63Ni, and 152Eu are the main radioactive nuclides. The total activity of radioactive nuclides was 2.36E + 15Bq at the end of 2007, 4.27E + 13Bq at the end of 2021, and 1.83E + 13Bq at the end of 2025. Furthermore, local sampling and radiometric analyses based on the HPGe gamma-ray spectrometer are also performed to verify the theoretical results, the ratio of theoretical activity values to the measured activity of the experimental sample is within 2.5 times, so the theoretical results are conservative. According to the classification standards for radioactive waste, the inner shell, outer shell, cooling water tank, sand layer, and heavy concrete shielding layer are all low-level waste. These results and conclusions can serve as a reference for the second phase decommissioning of the HWRR and the subsequent disposal of radioactive waste.

Thermal neutron capture cross-section and resonance integral measurements of 186W(n,γ)187W reaction using the thermal column neutron source at the Dalat research reactor

The thermal neutron radiative capture cross-section (σ0) and the resonance integral (I0) of the reaction 186W(n,γ)187W were measured by the thin foil activation method using the well thermalized neutron source at the graphite thermal column facility of the Dalat research reactor. The activities of the irradiated target and monitor samples were measured using a high resolution HPGe gamma-ray spectrometer. The recent updated values of gamma-rays intensities and decay half-life of the 187W nucleus were applied in this experiment to substantially improve the cross-section results compared to the previous measurements. The thermal neutron capture cross- section and the resonance integral of the 186W(n,γ)187W reaction were determined relative to the standard reaction 197Au(n,γ)198Au. The values obtained are 31.76 ± 0.63 and 429.2 ± 25.6 barns for σ0 and I0 respectively. Our results and previous measured values are compared, and discrepancies are discussed.

Radiological health assessment of infant milk in Erbil Governorate, Iraq.

In this research, the radioactivity caused by natural radionuclides (40K, 232Th, and 226Ra) was evaluated in infant milk consumed in Erbil, Iraq. The measurements were performed using an HPGe gamma-ray spectrometer. The variation of activity concentrations in milk samples was (99.56-256.9Bqkg-1) for 40K, (BDL-0.53Bqkg-1) for 232Th, and (0.27-5.59Bqkg-1) for 226Ra, as determined by the results. The radiological parameters of Eing, Dorg, and ELCR were calculated and compared to international standards. The correlation between computed radiological hazard parameters and natural radionuclides was analyzed statistically using Pearson's correlation. Overall, the results indicate that infant milk consumption in Erbil is radiologically safe and that consumers of these brands of milk are unlikely to be directly exposed to radiological health risks.

Assessment of Radiation Levels and Potential Radiological Hazards in the Soils of Riruwai Mining Area, North-Western Nigeria

This research aimed to assess the levels of natural radionuclides in the soil of the Riruwai mining area and to evaluate the radiological hazards associated with them. A total of sixty soil samples were collected from four sampling sites during the dry and wet seasons. The concentrations of uranium-238 (238U), thorium-232 (232Th), and potassium-40 (40K) were measured using an HPGe gamma-ray spectrometer, and the measured concentrations were used to estimate the internal and external hazards and gamma dose rate. The results of the analysis indicated that the concentrations of 238U and 232Th in all sampling sites and seasons were higher than the world average. The radionuclide levels in the soils showed a significant seasonal variation, with higher concentrations obtained during the dry season. The correlation analysis revealed a very strong positive relationship between all the radionuclides, which indicates a common origin (parent material). The gamma dose rate computations revealed that only active and abandoned mining sites have a mean gamma dose rate greater than the tolerable limit of 59.00 nGy/h. The internal and external radiological hazards assessments showed that only the active mining sites had the potential to be hazardous to human health. The researchers, therefore, recommend that comprehensive monitoring of mining operations and public education about the dangers of radiation exposure in the study area be carried out.

ASSESSMENT OF NORM LEVELS AND RADIOLOGICAL HAZARDS FROM PETROLEUM EXTRACTION IN THE ONSHORE OIL FIELDS, EGYPT.

Forty-nine different samples (crude oil, surface soil, produced water and sludge) from onshore oil fields in the Western Desert of Egypt were assessed for naturally occurring radioactive material (NORM) levels using HPGe gamma-ray spectrometer. The average activity concentrations of 226Ra, 232Th and 40K were 25±1.3, 26±1.0 and 21±1.5; 9.8±0.50, 11±0.40 and 94±6.9; 130±6.6, 91±3.4 and 41±3.0; and 180±16, 70±6.9 and 1300±110Bqkg-1 for crude oil, surface soil, produced water and sludge, respectively. The obtained NORM levels are much below the International Atomic Energy Agency NORM clearance levels. Radiological parameters (radium equivalent activity, absorbed dose rate and annual effective dose) were calculated and compared with the international acceptable limits. The annual effective doses are below 1 and 20mSv, the ICRP safety limits for the public and workers, respectively. Consequently, insignificant radiological hazards could present for the workers and surrounding environment from petroleum extraction activities in the studied area.

ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIATION EXPOSURE IN NEW BUILDING MATERIALS IN SPAIN.

Novel building materials were manufactured and analyzed for 226Ra, 232Th and 40K using an HPGe gamma-ray spectrometer. The results show that the highest value of 40K was 4530 Bq per kg which was measured in a sample containing fly ashes from olive stones. The highest values of 226Ra and 232Th activities were 181 and 185 Bq per kg, which were measured in a sample with fly ashes from the co-combustion of coal and coke, respectively. On the other hand, the lowest values of 40K, 226Ra and 232Th activities were obtained for samples incorporating mussel shells. The radiological health hazard parameters, such as radium equivalent activity (Raeq), activity concentration index (I), absorbed and effective dose rates, associated with these radionuclides were evaluated. These values are within the EU recommended limits in building materials, except for samples of concrete containing fly ashes from olive stones, coal and coke. This study has contributed to the inclusion of industrial wastes that have not been collected previously in the Naturally Occurring Radioactive Material (NORM) databases on radioactivity of building materials.

Measurement of the 7Li(p,p'γ)7Li reaction cross-section and 478 keV photon yield from a thick lithium target at proton energies from 0.7 to 1.85 MeV

The 7Li (p,p'γ)7Li reaction cross section and photon yield from a thick lithium target at proton energies from 0.7 to 1.85 MeV have been measured with a HPGe gamma-ray spectrometer. The spectrometer is calibrated on total and relative sensitivity by reference radionuclide sources of photon radiation. The measurement results are compared with those presented in the EXFOR nuclear reaction database and with other data published in open sources. The reliability of the results of previous studies is analyzed.

TANGRA multidetector systems for investigation of neutron-nuclear reactions at the JINR Frank Laboratory of Neutron Physics

In the framework of TANGRA-project at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear research in Dubna (Russia), two experimental setups (Fig. 1) have been designed and tested for investigation of 14-MeV neutron-induced nuclear reactions on a number of important for nuclear science and engineering isotopes. As a source of 14-MeV “tagged” neutrons we are using the VNIIA ING-27 steady-state portable neutron generator with embedded in its vacuum tube 64-pixel charge-particle detector. The “Romashka” system is an array of up-to 24 hexagonal NaI(Tl)-crystal scintillation probes, while the “Romasha” array consists of 18 cylindrical BGO-crystal detectors of neutrons and gamma-rays. In addition to these detectors there is a HPGe gamma-ray spectrometer and a number of Stilbene detectors that can be added for high-resolution gamma-ray spectrometry and neutron-gamma detection. The main characteristics of the neutron-induced nuclear reaction products can be investigated by commissioning the detectors in suitable for these experiments’ geometries. Both setups can be used for doing basic and applied scientific research, because they permit simultaneously to measure the energy, angle and multiplicity distributions of gamma-rays and neutrons, produced in the competitive neutron-induced nuclear reactions (n, n’γ), (n,2n), (n, xnγ) and (n, f) in pure or complex substances.

Validation of Full Energy Peak Efficiency Calibration of HPGe Gamma-Ray Spectrometer Using Empirical Efficiency Curve Transfer

Validation of Full Energy Peak Efficiency Calibration of HPGe Gamma-Ray Spectrometer Using Empirical Efficiency Curve Transfer

Transfer of40K,226Ra and210Pb from soil to plants in various locations of El-Jadida agricultural area (north-western Morocco)

The present study examines the radionuclides (40K,226Ra and210Pb) concentrations in soil and plants collected from El Jadida agricultural area. The transfer factors of radionuclides from the soil to different components of the plants (stems, roots, leaves, and fruits) was also determined and assessed. The plants include various vegetable crops, including pumpkin, zucchini, beans, fennel, potato, sunflower, broccoli, onion, carrot, cabbage, tomato, and mallow from three different locations. A wide-range HPGe gamma-ray spectrometer is used for radionuclide activity measurement. The radionuclides activities of soil samples display a wide range of variability from one location to another. The concentrations of226Ra vary between 18 ± 1 Bq.Kg-1and 80 ± 4 Bq.Kg-1, the concentrations of210Pb range from 49.7 ± 4.4 Bq.Kg-1to 269 ± 16 Bq.Kg-1, and the40K values fluctuate between 94,1 ± 6,5 and 286,1 ± 15,3 Bq.Kg-1. The study showed that the transfer factor for K-40 is more significant than Pb-210 and Ra-226, mainly related to the use of fertilizers rich in potassium in the agricultural areas, leading to its concentrations increase.

Measurement of Natural Radionuclides and Assessment of Radiation Hazard in Coal from Parts of China.

To study the content of radionuclides in coal and to assess its associated radiological impact on the environment for potential radiological risk assessment, a total of 40 coal samples were collected from various mining areas in eight provinces of China. The specific activities of 226Ra, 232Th, 40K, 210Pb, and 238U were measured in all samples using an HPGe gamma-ray spectrometer, and results were compared with available data from other similar studies. The results reveal that the radium equivalent activity was 74.20 Bq kg-1, external hazard index was 0.20, internal hazard index was 0.27, representative gamma index was 0.52, and indoor and outdoor annual effective dose rates were 0.16 nSv y-1 and 0.04 nSv y-1, respectively. Absorbed gamma dose rate in air was 32.87 nGy h-1. In general, these values are lower than the respective threshold limits recommended by UNSCEAR, and the radiation risk to the public is extremely small.

Standardization of krypton-85 and its calibration on HPGe gamma-ray spectrometer

In this paper, standardization of the activity concentration of gaseous beta-emitting radionuclide 85Kr is introduced. The measurement was performed at the recent-established primary standard at the National Institute of Metrology of China (NIM), which consists of a set of internal gas proportional counters of different length. Samples suitable for High Purity Germanium gamma-ray spectrometry measurement were also prepared, and efficiency calibration at an energy of Eγ = 514 keV with standardized 85Kr source in a given geometrical container is presented.

Measurement of natural radioactivity in Kufa River, Iraq

The levels of natural radioactivity for 226Ra, 228Ra and 40K were measured for 28 water samples taken from Kufa River inside Governorate of Al-Najaf Al-Ashraf in Iraq. Measurements were performed using a HPGe gamma-ray spectrometer system. The activity concentration (mBq/l) varied from 17.70 ± 1.83 to 58.90 ± 3.34, 4.60 ± 0.86 to 37.10 ± 2.44 and 142.56 ± 07.96 to 652.67 ± 17.03 for 226Ra, 228Ra and 40K, respectively. The average values of activity concentration for 226Ra, 228Ra and 40K were 35.14 (mBq/l), 19.13 (mBq/l) and 352.84 (mBq/l), respectively. Annual effective dose in (nSv/y) was also calculated and all the annual effective dose values are much lower than the recommended values. So the water of Kufa River in Najaf Governorate, Iraq is safe to be used by humans either as drinking water or for daily routine activity.

RADIATION EXPOSURE FROM NATURAL RADIONUCLIDES IN BUILDING MATERIALS.

Building materials from Iberian Peninsula (Portugal and Spain) were collected and analysed for 226Ra, 232Th and 40K using HPGe gamma-ray spectrometers. The results show that the highest mean value of 226Ra and 232Th activities are 2168 and 390 Bq kg-1, respectively, measured in zircon. For 40K, this value is 1290 Bq kg-1, measured in granite. The mean concentrations of the three radionuclides in the different building materials, excluding the zircon and the industrial by-products (ashes, gypsum and phosphogypsum), are 62, 31 and 519 Bq kg-1 for 226Ra, 232Th and 40K, respectively. The radiological health hazard parameters: radium equivalent activity (Raeq), activity concentration index (I) absorbed and effective dose rates, associated with these radionuclides, were evaluated. These values are within the EU recommended limits in building materials, except for same samples of aggregates, granites, ceramics, phosphogypsum and zircon. This study will contribute for the worldwide data pooling on the radioactivity of the building materials.

Assessment of natural radioactivity levels in the Ajali Formation, Enugu, South Eastern Nigeria

Activity concentrations of the radionuclides (238U, 232Th and 40K) were analysed using high resolution co-axial HPGe gamma ray spectrometer system to know the implication where groundwater is sourced from Enugu, South-East Nigeria. The activity concentration of 238U ranges from 37 ± 4 to 74 ± 6 Bq kg−1 with the highest value of 74 ± 6 Bq kg−1 noted in the thin coal sample. The 232Th activity level in the rock samples ranges from 58 ±5 to 85 ± 7 Bq kg−1 with the higher value of 89 ± 7 Bq kg−1 reported in the coal sample. For 40K, the activity concentration varies from 140 ± 19 to 293 ± 25 Bq kg−1 with the highest value of 293 ± 25 Bq kg−1 reported in coal samples whereas lowest value of 140 ± 19 Bq kg−1 was noted in Ajali sandstone in the study area (Enugu State). The higher activity levels of 238U, 232Th and 40K reported in coal samples may be due to the closer clusters of weathered surface of Ajali sandstone that overlays the thin coal layer with an escarpment being spread out, implying higher permeability towards deeper direction. All the values are within the recommended level when compared with United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2000). Further research on groundwater activity concentration and rock geochemistry is required within the study area. This will allow for a comprehensive conclusion to be drawn on the level of exposures to the inhabitants relying on groundwater for consumption.

Environmental radionuclides as contaminants of HPGe gamma-ray spectrometers: Monte Carlo simulations for Modane underground laboratory

The main limitation in the high-sensitive HPGe gamma-ray spectrometry has been the detector background, even for detectors placed deep underground. Environmental radionuclides such as 40K and decay products in the 238U and 232Th chains have been identified as the most important radioactive contaminants of construction parts of HPGe gamma-ray spectrometers. Monte Carlo simulations have shown that the massive inner and outer lead shields have been the main contributors to the HPGe-detector background, followed by aluminum cryostat, copper cold finger, detector holder and the lead ring with FET. The Monte Carlo simulated cosmic-ray background gamma-ray spectrum has been by about three orders of magnitude lower than the experimental spectrum measured in the Modane underground laboratory (4800 m w.e.), underlying the importance of using radiopure materials for the construction of ultra-low-level HPGe gamma-ray spectrometers.

Studies on distribution of radionuclides and behavior of clay minerals in the soils of river environs

In the present investigation, the activity concentrations of radionuclides in the soils of Cauvery river environs were measured using HPGe gamma ray spectrometer. FTIR spectroscopy was used to find minerals present in soil samples. The mean values of 40K, 226Ra and 232Th in the soil samples was found to be 132.9, 22.95 and 26.88 Bq kg−1 respectively. The estimated absorbed dose rate and hazard indices were found to be within the safety limits. The extinction coefficients for quartz, sepiolite and kaolinite in soil varied from 0.64 to 37.24, 0.39 to 34.47 and 9.66 to 35.81 respectively. The correlation matrix showed that the clay mineral like kaolinite influences the increase in activity concentration of radionuclides.

Soil-to-plant transfer factors of natural radionuclides (226Ra and 40K) in selected Thai medicinal plants

A soil-to-plant transfer factor (TF) is an important parameter that could be used to estimate radionuclides levels in medicinal plants. This work reports concentrations of natural radionuclides (226Ra and 40K) and TFs in six Thai medicinal plants grown in central Thailand using an HPGe gamma ray spectrometer. Either root, leaf, or flower parts of each medicinal plant were selected for use in the investigation according to their practical uses in traditional medicine. The results showed that due to K being essential in plants, 40K had higher arithmetic means of activity concentrations and geometric means of TFs (geometric standard deviations in parentheses) of 610 ± 260 Bq kg−1 dry weight (DW) and 2.0 (1.4), respectively, than 226Ra, which had the activity concentrations and TFs of 4.8 ± 2.6 Bq kg−1 DW and 0.17 (1.8), respectively. The results also showed that the leaves of medicinal plants had higher activity concentrations and TFs than root and flower parts, probably due to higher metabolic activities in leaves. Furthermore, there was good agreement between the results from the current work and other similar reports on medicinal plants. The information obtained from this work could strengthen knowledge of natural radionuclides in plants and particularly increase available TF data on Thai medicinal plants.

Natural Radioactivity Measurement and Assessment of Radiological Hazards in Some Building Materials Used in Bangladesh

The radioactivity concentrations of 226Ra, 232Th and 40K in 24 samples of natural and manufactured building materials commonly used in Bangladesh were measured using HPGe gamma ray spectrometer. The results in the present study were compared with the world average and also with the reported data available in literature. The radium equivalent activity, the absorbed dose rate, annual effective dose, external and internal hazard indices, gamma index, alpha index, annual gonadal dose equivalent and excess lifetime cancer risk were also evaluated to assess the potential radiation hazards associated with these building materials. All samples under investigation were found to be within the recommended safety limit and do not pose any significant radiation hazards. This study can be used as a reference for more extensive studies of the same subject in future.