Portable Survey Meter Research Articles

COMPARISON OF GAMMA ABSORBED DOSE RATES IN THE AIR MEASURED WITH A PORTABLE SURVEY METER AND THE SOIL RADIOACTIVITY MEASUREMENTS.

To compare the measurement results of a portable survey meter with a soil-based dose rate assessment method, the gamma absorbed dose rates in the air were measured at 27 sites. The soil-based gamma absorbed dose rates in the air were calculated using established conversion factors and the activity concentrations of 226Ra, 232Th and 40K of the soil at the sites. The gamma absorbed dose rate averages of the portable survey meter, and computing from the activity concentrations in the soil were 65.8±4.26 and 64.8±3.68 nGy⋅h-1, respectively. A significant positive correlation was found in the comparison between the evaluated gamma absorbed dose rates from soil radioactivity and in the air. Conversion factors based on the local soils converting to the absorbed dose rate were computed from the portable survey meter data and the soil activity concentrations, and it was compared with others.

Performance tests of the B-RAD radiation survey meter

This article discusses performance tests of the B-RAD by ELSE NUCLEAR. The B-RAD is a portable survey meter for γ-ray spectrometry and γ-ray dose rate measurements able to operate in the presence of a strong magnetic field. The detector uses a 15 mm right cylinder LaBr 3 crystal coupled with a 16-pixel Silicon Photomultiplier array. The crystal, the photodetector and the front-end electronics (the probe) are enclosed in a case connected with a cable to a control unit. The latter includes the main electronics, a customised battery pack, two displays and a Faraday cage.More in detail, this paper investigates the instrument performance inside magnetic field, including linearity of its response and its angular response. An operational test is also reported to demonstrate a practical application. The performed tests show that the B-RAD can operate inside magnetic fields up to 2.5 T. Two small shortcomings were observed: a pulling force is felt especially on the control unit, which becomes rather intense for values of the magnetic fields above 1 T, and a slight reduction of the signal gain with increasing magnetic field intensity when the control unit is inside the field. The latter causes a variation of the measured dose rate of less than 10% at 1.5 T. The response of the B-RAD with dose rate is linear up to 20 mSv/h with discrepancies between the reference and the measured dose rate within 10%. The response is isotropic from −120° to ＋120°; beyond this limit the measured dose rate drops by 66% probably because of the scattering of the source photons with the case and some shielding effects.

Soil radioactivity levels and radiation exposure to the population in Aswan and Abu Simbel areas, South of Egypt

Gamma-ray spectrometer and Lucas cell were used to evaluate the activity concentrations of 226Ra, 232Th, 40K, and 222Rn mass exhalation rates for 37 topsoil samples from different sites in Aswan city, Aswan-Abu Simbel highway, and Abu Simbel village, south of Egypt. The average activity concentration of 226Ra, 232Th, and 40K was 23.3 ± 1.7, 21.1 ± 1.2, and 283.4 ± 22.3; 21.2 ± 1.7, 15.2 ± 1.0, and 89.4 ± 10.5; 29.0 ± 2.2, 26.3 ± 1.5, and 79.5 ± 9.7 Bq kg−1 for soil from Aswan city; Aswan-Abu Simbel highway; and Abu Simbel village, respectively. Activity ratios for the studied radionuclides were calculated, and 232Th/226Ra ratios in most of the sampling sites were <1.1 (natural equilibrium ratio). The mass ratio of Th/K was computed, and the results showed the presence of three main types of clay minerals (montmorillonite, kaolinite, and heavy thorium-bearing minerals) in the studied areas. Radon measurements showed that soil from Aswan city has the highest average value of 222Rn mass exhalation rate (20.6 ± 1.7 mBq kg−1 h−1). The ambient dose equivalent rates were measured in situ using the portable survey meter, and the obtained values showed no significant differences between the studied areas. In general, the results indicate that the studied areas can be considered as areas with normal background radiation levels, and therefore the risks of exposure to natural radiation are minimal.

The Mini Labyrinth Benchmark for Radiation Protection and Shielding Analysis

The Mini Labyrinth experiment is a neutron and gamma shielding experiment currently being developed at the Slovak University of Technology, Bratislava (STU). The STU Mini Labyrinth consists of NEUTRONSTOP shielding blocks, water tank, PuBe neutron source, and graphite prism. This article describes the second construction version of the Mini Labyrinth experiment and presents the newest results of the neutron and gamma fields’ simulation and measurement. The PuBe neutron source with the emission rate of 1.06E7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{n}\cdot \text{s}^{-1}$ </tex-math></inline-formula> was used in the experiment. The measurement of gamma ambient dose equivalent H*(10) and neutron count rates is performed by the Thermo Scientific RadEye portable survey meter and the SNM-11 BF3-filled corona detector. The simulation part was carried out using the state-of-the-art MCNP6 and SCALE6 MONACO stochastic calculation tools, considering the detailed geometry of the Mini Labyrinth and a combined neutron and gamma source of particles. The comparisons were performed between codes and the experiment. The propagation of cross-sectional uncertainties was investigated through the shielding analysis. Almost perfect agreements between simulation codes were achieved. The comparison with measurement suggests the further needs of room effect assessment.

Development of two types of lightweight portable neutron survey meter

Development of two types of lightweight portable neutron survey meter

Characterization of stilbene and EJ-276 scintillators coupled with a large area SiPM array for a fast neutron dose rate detector

A 1-inch stilbene and EJ-276 (plastic) organic scintillators were characterized in view of their use in a portable survey meter for fast neutron detection and dose rate measurements in radiation protection. They were coupled with a large area Silicon Photomultiplier (SiPM) array and characterized in terms of neutron/γ–ray (n/γ) discrimination capability, count rate linearity, count rate saturation effects, temperature stability and neutron detection efficiency. A Pile-Up Rejection (PUR) algorithm was developed and tested to increase their count rate linearity with increasing dose rate. Results show that the stilbene exhibits better performance compared to the plastic in terms of: Pulse Shape Discrimination (PSD) with a Figure Of Merit (FOM) of 1.5 vs. 1.1, energy resolution (15% vs 20% at 662 keV) and fast neutron efficiency (12% vs. 9% with an AmBe source). For both scintillators, the dose rate response is linear up to 1 mSv/h with a 137Cs γ-ray source. With a neutron source, the response is linear, and the FOM is almost constant for dose rates up to 1.5 mSv/h. The PUR reduces the false neutron events by one order of magnitude when the detectors are irradiated with a γ-ray source up to 10 mSv/h, and it correctly works when irradiated with an AmBe source at 1.5 mSv/h together with a 137Cs source up to 60 μSv/h. The proposed PUR algorithm is promising but needs to be tested with a higher intensity mixed n/γ field. The temperature stability of both detectors was also studied in the temperature range from −10 °C to ＋40 °C. The light yield increases by around 25% for both detectors when reducing the temperature. The variation of the neutron count rate is around 10% in the same temperature range. This work provides a complete overview of the performance of these detectors and a coherent comparison between the two types of scintillators with the same experimental setup.

MEASUREMENT OF RADON CONCENTRATION IN SOIL SAMPLES OF MAZAT AND KAFI-HABU MINING SITES, PLATEAU, NIGERIA

Radon and its short-lived progenies contributed significantly to natural background radiation. Long-term exposure to such radiation increases the probability of lung cancer to persons. To assess the radiological hazards associated with the inhalation of radon gas from ore dust in Mazat and Kafi-Habu mining sites of Plateau, Nigeria, 12 soil samples from an abandoned tailing dump ground were collected and analysed for radon using RAD-7 electronic detector. The dose rate of each sampling point was directly measured using RADOS RDS -120 portable survey meter. The results gave a mean radon concentration ranging from 771.51 ± 21.9 Bq/m3 to 5666.13 ± 28.8 Bq/m3 with 3451.13 ± 42.9 Bq/m3as the average value for all measurements. The average concentration of measurements from Mazat and Kafi-Habu is 3671.6 ± 41.2 Bq/m3 and 3010.16 ± 46.5 Bq/m3 respectively. The average values obtained from the analysis are significantly higher than the upper limit of 300 Bq/m3 set by the International Commission on Radiological Protection (ICRP) suggesting quick remediation on the host communities. The geometrical mean value of Dose Rate (DR) and Annual Effective Dose Equivalent (AEDE) were 870 nGy/hr and 1.04 mSv/yr respectively. Again, these values are above the global average limits of 59 nGy/hr and 1 mSv/yr. The result indicates that miners working in those sites and dwellers of the study areas are at higher risk of getting exposed to radon and need to employ protective measures. This work is useful in monitoring and control of radon level for the on-site workers and the

The Mini Labyrinth – a Simple Benchmark for Radiation Protection and Shielding Analysis

The Mini Labyrinth experiment is a simple neutron and gamma shielding experiment developed at STU, inspired by the ALARM-CF-AIR-LAB-001 ICSBEP benchmark experiment. The STU Mini Labyrinth is approximately ten times smaller and consists of NEUTRONSTOP shielding blocks. This paper describes the second version of the Mini Labyrinth experiment and presents the results of the neutron and gamma fields simulation and measurement. The PuBe neutron source with the emission rate of 1.0E7 n.s-1 was utilized in the experiment. The measurement of gamma ambient dose equivalent H*(10) and neutron count rates is performed by the Thermo Scientific RadEye portable survey meter. The simulation part was carried out using the state-of-the-art MCNP6 and SCALE6 MONACO stochastic calculation tools taking into account the detailed geometry of the labyrinth and a combined neutron and gamma source of particles. The comparisons were performed between codes and an experiment, based on the dose rate in the unique detection positions and using a 2D map of neutron and photon fluxes. The propagation of cross-section uncertainties was investigated through the shielding analysis. Partial agreement between codes and measurement was achieved, however serious discrepancies near the PuBe source were identified.

Vertical distribution of the radon concentration at Batu Pahat district, Johor, Malaysia

This study investigated the vertical distribution of radon, 222Rn concentrations in soil gas for different soil types and found the relation between the measured gamma dose rates and radon concentrations. The 222Rn concentrations in soil gas were measured at depth of 20 cm, 60 cm, 80 cm and 100 cm using semiconductor detector (RAD7) coupled with soil gas probe. The overall activity concentrations of 222Rnin soil were ranged from Minimum Detectable Activity (MDA)to 54000 ± 3000 Bq m−3 in Batu Pahat District. The results showed that the overall highest concentration of 222Rn was recorded at 40 cm depth for most of the soil types, which could be the most reliable for taking the radon measurements than other depths. Soil type 32 (Dystric Nitosolse Orthic Ferrasols-Rengam Jerangau) has the highest radon concentration, which was 12,462 ± 5237 Bq m-3. The gamma dose rates (GDR) above 1 m were measured using portable survey meters (Ludlum 19). A good relationship between radon concentrations in soil gas and the measured gamma dose rates was observed using Pearson Correlation. The results of 222Rn concentration in soil gas obtained from this study were in agreement with results reported by other researchers.

Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera.

We present experimental protocols for visualizing various low-level gamma radiation sources in the ambient environment. Experiments were conducted by using a low-cost, high-sensitivity, omnidirectional, gamma-ray imaging Compton camera. In the laboratory, the position of a sub-MeV gamma radiation source such as 137Cs can easily be monitored via omnidirectional gamma-ray imaging obtained by the Compton camera. In contrast, a stationary, wall-mounted dose rate monitor cannot always successfully monitor such a source. Furthermore, we successfully demonstrated the possibility of visualizing the radioactivity movement in the environment, for example, the movement of a patient injected with 18F-fluorodeoxyglucose (18F-FDG) in a nuclear medicine facility. In the Fukushima field, we easily obtained omnidirectional gamma-ray images concerned with the distribution on the ground of low-level radioactive contamination by radioactive cesium released by the Fukushima Daiichi nuclear power plant accident in 2011. We demonstrate clear advantages of using our procedure with this camera to visualize gamma-ray sources. Our protocols can further be used to discover low-level gamma radiation sources, in place of stationary dose rate monitors and/or portable survey meters used conventionally.

Radiological characterization of the irt-5000(14-Tammuz) research nuclear reactor at Al-Tuwaitha nuclear center in Iraq

Measurements were made at the destroyed nuclear reactor IRT-5000 (14-Tammuz research nuclear reactor at AL-Tuwaitha Nuclear Center in Iraq) to provide a basic comprehensive radiological characterization and to assess risk and dose for the workers in the workplace. Samples were collected from the site and analyzed, as well as using a portable survey meter to determine the external exposure dose rates. The quantity and quality of radionuclides were determined using gamma spectrometry techniques. The dose rate measured within the reactor core body ranged from 55 to 1250 mSv/h. The maximum dose was recorded in the middle of the corner near the horizontal experimental channel number seven, with activity concentration of 19.97 GBq estimated from Co-60 isotope. Most samples were contaminated with Cs-137, Co-60, and Eu-152 isotopes. The highest activity concentration of Cs-137 is 14772.41 ± 99.91 Bq/L and Co-60 is 7642.22 ± 40.02 Bq/kg, were found in slag from reactor tank. Two scenarios were developed based on the water level of the reactor tank. Assuming there are three locations for workers on the reactor surface. The annual dose of workers on the surface of the reactor (when the reactor tank is empty) ranges from 116 to 153 mSv, which is higher than the annual dose limit for workers. Therefore, workers will be subjected to the principle of As Low As Reasonable Achievable (ALARA) during all phases of dismantling nuclear reactor IRT-5000 (14-Tammuz) as recommended by International Atomic Energy Agency (IAEA).

Natural Radioactivity and Radiological Impact Assessment of Soil, Food and Water around Iron and Steel Smelting Area in Fashina Village, Ile-Ife, Osun State, Nigeria

This study assessed the natural radioactivity and radiological health impact of thirty-eight (38) samples of soil, food and water in Fashina village, Ile-Ife, Osun State, Nigeria using portable survey meter with a Global Positioning System (GPS) and well-calibrated NaI(Tl) detector system The mean exposure rates in the study area were 0.14 μSv hr -1 and 0.12 μSv hr -1 in soil/food and water samples respectively. The mean radioactivity content obtained for 238 U, 232 Th and 40K were 12.14 ± 4.17Bq kg -1 , 23.23 ± 7.67 Bq kg -1 and 270.14 ± 61.79Bq kg -1 respectively in soil samples and 8.56 ± 2.80Bq kg -1 , 13.17 ± 4.48Bq kg -1 and 89.41 ± 24.15Bq L -1 respectively for 238 U, 232 Th and 40K in water samples. The mean values of 30.91, 15.64 and 12.47 nGy h -1 were obtained for the absorbed dose rate in soil, food and water, respectively, while 37.90, 178.79 and 1085.23 μSv y -1 were obtained for the Annual Effective Doses (AED). Similarly, the Radium equivalent (Raeq) were 66.16 Bq kg -1 , 34.28Bq kg -1 and 27.31BqL -1 , in soil, food and water, respectively. The external and internal radiation hazard indices were 0.18 and 0.21, 0.09 and 0.12, 0.07 and 0.09, respectively for soil, food and water. The values obtained for the Excess Lifetime Cancer Risk (ELCR) in (x 10 -3 ) were also 0.13, 0.63 and 3.80 for the soil, food and water samples, respectively. It was found that the values of some exposure rate, radioactivity contents and radiological impact parameters in the study area which were higher than those of the control area and the world average values poses a serious health risk to the environment and its inhabitants. Keywords : Radioactivity, Scrap Metal, Gamma Spectrometry, Radiological Impact Parameter

ASSESSMENT OF RADIOACTIVITY LEVELS AND TRANSFER FACTOR OF NATURAL RADIONUCLIDES AROUND IRON AND STEEL SMELTING COMPANY LOCATED IN FASHINA VILLAGE, ILE-IFE, OSUN STATE, NIGERIA

This study assessed the radioactivity levels and transfer factor of natural radionuclides around iron and steel smelting company located in Fashina village, Ile-Ife, Osun State, Nigeria. This was with a view to evaluate the exposure rate of the study area, determine the radionuclides present and activity concentration (238U and 232Th and 40K) in the samples and evaluate the soil-to-food transfer ratio of the radionuclides. A portable survey meter with a Global Positioning System (GPS) were used for in-situ investigation and a well-calibrated NaI(Tl) detector system was used for the radioactivity measurement of the samples. A total of 38 samples comprising soil, food and water were collected at the study area (Fashina) and control area (Opa) in Osun state, Nigeria for spectrometry analysis. The soil and food samples were oven dried, pulverized and sieved while water samples were acidified with 10 mL of 11 M HCl per litre to prevent adsorption of radionuclides with the wall of the container. All the samples were then sealed and kept for at least 28 days in radon impermeable cylindrical container so as to reach secular equilibrium. The mean exposure rates in the study area were 0.14 µSv hr-1 and 0.12 µSv hr-1 for the control environment. The mean radioactivity content obtained for 238U, 232Th and 40K were 12.14 ± 4.17 Bq kg-1, 23.23 ± 7.67 Bq kg-1 and 270.14 ± 61.79 Bq kg-1 respectively in soil samples and 8.56 ± 2.80 Bq kg-1, 13.17 ± 4.48 Bq kg-1 and 89.41 ± 24.15 Bq kg-1 respectively in food samples. Similarly it was 7.64 ± 2.95 Bq L-1, 10.04 ± 3.43 Bq L-1 and 69.04 ± 15.49 Bq L-1 respectively for 238U, 232Th and 40K in water samples. The transfer factor from soil to food for 238U, 232Th and 40K were calculated from the activity concentrations of soil and food, while the means were 0.73, 0.61, and 0.39 respectively in the study area.

Comparison of Gamma Dose Levels in Assessed by Various Methods

Abstract Indoor and outdoor gamma dose rates were evaluated along the coastal regions of Thangasherry, Kollam district, Kerala through direct measurements using a GM based gamma dose survey meter, time integrated measurement using CaSO4:Dy based thermo luminescent dosimeters (TLDs) and theoretically gamma spectrometry of soil samples. The mean values of indoor and outdoor Annual Effective dose rates observed were 1.26±1 mSv/yr and 0.378±0.08 mSv/yr, respectively with an indoor to outdoor dose ratio of 0.86. The radioactivity content in the soil samples, the absorbed dose rate, annual effective dose equivalent, radium equivalent activity, internal and external hazard indices , the representative gamma index and alpha index (Igamma and Ialpha), the annual gonad dose equivalent (AGDE) and the excess lifetime cancer risk (ELCR) were determined and compared with recommended values. Correlation study showed that the dose estimated from the TLDs is better correlated with that measured directly using the portable survey meter. The results of natural radioactivity levels in the soil samples has been compared with the levels reported in other Indian cities as well as other parts of the world.

Health Risk Implications of Terrestrial Gamma Radiation Dose Rate in Central Jakarta, Indonesia: Short Communications

Terrestrial gamma radiation dose (TGRD) rate measurement has been conducted around downtown region of Central Jakarta Indonesia. The real time count data was taken 1 m above the ground in eight sub district locations by using a portable gamma Surveymeter of Exploranium GR-135 Plus Model. The reading position was detemined using Garmin GPSMAP 62s. The average value of TGRD rate of (47.76 ± 18.24) nSv h-1 ranged from 6.40 nSv h-1 to 120.90 nSv-1, it is higher than Indonesia. The annual effective dose rate of 0.058 mSv. Its contributes to fatal cancer risk of about 3.22 x 10-5 per year for each individual in Central Jakarta. For the subdistrict TGRD rate value was variated, however all the result is not high enough to cause for alarm.

Design and construction of portable survey meter

This work was aimed to design and construction of portable survey meter for radiation dose measuring. The designed system consists of 4 main parts consisting of low voltage power supply, radiation detection, radiation measurement and data display part on android phone. The test results show that the ripple voltage of low voltage power supply is less than 1%, the maximum integral counts are found to be 104 counts per second and the maximum distance of wireless commination between the server and the client is about 10 meter. It was found that the developed system had small size and light weight for portable instrument.

Image Quality Assessment and Radiation exposure in Intra Oral Dental Radiography

In this study, an intra oral dental unit (Siemens-70) at King Abdul Aziz University (KAU) Dental Hospital was selected and investigated for visual image quality assessment and radiation protection purposes. Radiation dosimetry for determining the optimum image quality with the lowest radiation exposure to the patient was carried out. A DXTTR dental radiography trainer phantom head and neck, portable survey meter Model RAD EYE-B20, and radiation dosimetry system RADCAL Acuu-pro were used in this study. RADCAL Accu-pro is a non-invasive kV system, reliable instruments to measure and diagnose all X-ray machines including dental units. The radiation exposure to patients in (mGy) was measured using RADCAL ionization chamber Model 10×6-6. The best image quality with the lowest exposure dose was assessed for conventional intraoral X-ray film (Kodak type E) and the digital processing sensor (RVG 5200). Radiation survey level was done during this study for safety and protection purposes.

The Radiological Contamination in AL-Tahreer Tower Building at Baghdad City

In this study, evaluation of the radioactivity for AL-Tahreer Tower Building (the Turkish restaurant previously) which located in the center of Baghdad city was implemented. The contamination resulted from bombing the Building by the depleted uranium projectiles. The building consists of 14 floors besides the basement. Radiological characterization was implemented using field and laboratory measurements. The results of radiological surveys by using portable survey meter (CAB-counts per second (cps)) indicated the presence of contaminated soil reached to 60 cps (more than 120 the background radiation level) in addition to the presence of small particles of depleted uranium shells with high levels of contamination reached to 90 cps, compare with (0.5 cps) the background level. While the results of maximum exposure dose rates were 0.6 µSv/hr when the detector of survey meter (Ludlum) put on the contaminated regions at a distance about (0.5 cm). The natural background level of the building at distance one meter was 0.9 µSv/hr. Soil samples had been collected and prepared for measuring according to the international standards and specifications, using gamma spectrometry system which consist of High-purity Germanium Detector with efficiency of 40% and resolution 2.0 keV for Energy 1.332 MeV of ⁶⁰Co, The laboratory results indicated the presence of high concentrations of Th-234 and Pa-234m isotopes (1550.1 & 3179 Bq/kg respectively) in the soil samples taken from the floors, while the concentrations of Th-234 in natural background soil sample were nearly 40 Bq/kg, Pa-234m not detected. According to the results of radiological characterization (field and laboratory), which showed an increase in radioactivity in the AL-Tahreer Tower Building the protective procedures had been adopted, where the contaminated soil and wastes resulted from decontamination processes collected in the 26 drum of capacity 220 liter, after the transfer of drums to the temporary storage at Tuwaitha site with cooperation of the Directorate of Radioactive Waste Management & Treatment at (MOST). Now the building within the background radiation levels and released by the regulatory body “Radiation Protection Center (RPC)/ Ministry of Environment (MOEN)”.

A comparative study of terrestrial gamma dose rate in air measured by thermoluminescent dosimeter, portable survey meter and HPGe gamma spectrometer

In this paper, three different widely-used measurement techniques for environmental gamma dose rate were studied and compared, i.e., the thermoluminescent dosimeter, the portable survey meter and the spectrometric analysis. Thirteen investigation sites were selected, and the TLDs were arranged to accumulate the radiation signals during an interval of about one quarter, the instant dose rates by using a portable survey meter were collected around the site, and top surface soils were sampled in the surroundings for radionuclides analyzing in laboratory. The results from these methods were compared, which revealed high correlations. The differences and possible uncertainties for the three methods were analyzed, inspired a further study should be conducted to have more successful estimation of dose rate in surface air.

Assessment of a relative contribution of terrestrial background radiation in the test field by using RADIAGEMTM 2000 portable survey meter

This study is focused on the radiological investigation of terrestrial gamma radiation in the test field with soil samples from different minefields in the Federation of Bosnia and Herzegovina. Measurements of ambient dose equivalent rate, commonly referred to as ?air dose rate?, in the test field located in the Tuzla Canton, were performed by RADIAGEMTM 2000 portable survey meter, based on energy-compensated Geiger-Muller counter. Its performances were tested in the laboratory conditions with gamma point sources. Since all the samples in the test field were exposed to the same cosmic radiation, there was a possibility to assess a relative contribution of terrestrial gamma radiation due to soil samples of different composition. One set of measurements in the test field was performed with RADIAGEMTM 2000, at a height of about one meter above the ground and basic statistical parameters indicated that there was no significant difference of terrestrial gamma radiation from different soil samples. The other set of measurements was carried out with the same device placed on the ground in the test field. Processing of experimental data on terrestrial gamma radiation has shown that it was possible to make a difference between relative contributions of terrestrial gamma radiation from individual soil samples. The results of investigation could be useful for multiple purposes of public interest.