Radon alpha track counting on solid state nuclear track detector by an ImageJ-based software macro.

Radon (222Rn) is a radioactive gas emanating from geological materials. Inhalation of this gas is closely related to an increase in the probability of lung cancer if the levels are high. The usual methodology for the quantification of radon by passive methods is the use of etched solid-state nuclear track detectors, frequently in combination with optical microscopes or image scanning for image acquisition and software-based image processing for track counting. Currently available commercial instrumentation, as the Radosys microscopy system, is quite expensive, so the development of alternative methodologies is desirable. In this work, a simple, fast and low-cost image acquisition system for the determination of tracks in chemically etched CR-39 solid-state nuclear track detectors to quantify 222Rn alpha tracks has been proposed. The image of the detector surface is obtained by a conventional light stereoscopic microscope, transmitted by a CCD camera into the computer, and analyzed by the ImageJ open-source software. This methodology was employed to analyze 45 samples collected in dwellings and caves located in the region of Extremadura (Southwest Spain). Results show a good correlation coefficient of r2 = 0.98 between the reference and purposed methodology and excellent repeatability, demonstrating that the system enables routine counting tracks for radon measurement as an alternative to the Radosys microscopy instrument.

A case study on the correlation between radon and multiple geophysicochemical properties of soils in G island, Korea, and effects on the bacterial metabolic behaviors.

This study was conducted to assess the natural radiation intensity of radon observed from 'G' islands and its effects against Bacillus pumilus, predominantly found throughout the field survey. The physicochemical properties and microbial characteristics were simultaneously investigated and compared. From these studies, it was confirmed that the areal distribution of radon concentration varied from 920 Bq/m3 to 3367 Bq/m3 depending on the soil depth, lithology, or geophysicochemical properties (including pH, moisture content, and grain size) inherently subject to each location. Particularly, the slightly acidic (pH < 6) and low-fertility soil with a higher level of radon concentration exceeding 3000 Bq/m3 had a considerably low level of bacterial density. In contrast, the fertile soil of a relatively middle level of radon radioactivity revealed a much larger bacterial community density, dominated by Bacillus spp., Pseudomonas sp., Paenarthrobacter sp., and Microbacterium sp. Furthermore, the monitored metabolic activity and growth of Bacillus pumilus against the various radon exposure conditions clearly indicated that radon could be considered as the potential ecological risk to natural environmental habitats of microbial soil biota.

Some physicochemical parameters and 226Ra concentration in groundwater samples of North Guilan, Iran.

The 226Ra concentration and some physicochemical parameters have been measured in thermal spring waters used for medical therapy and drinking purposes in the Astara basin of North Guilan, Iran. The radon emanation method was performed using the AB-5 photomultiplier tube to measure the 226Ra concentration in water samples. Also, the physicochemical parameters of the water were measured in situ using a portable multimeter-VWR multi. The average concentrations of 226Ra were ranged between 3.4 ± 0.06 to 38.2 ± 0.08 mBq l-1. For all samples, the 226Ra concentration values range is lower than the maximum admissible value recommended by the WHO report. The relation between the physicochemical parameters and 226Ra activity concentration of groundwater was assessed. The results indicate a significant correlation coefficient between 226Ra concentration and T, as well as acidity pH. Anomalously high 226Ra concentrations in groundwater are preferentially found in high temperate and electric conductivity along with the acidic environment.

Partition Coefficients and Diffusion Lengths of 222Rn in Some Polymers at Different Temperatures.

In this work, the partition coefficients K and diffusion lengths L D of radon in some polymers are experimentally determined for several temperatures in the range T = 5-31 °C. Some of the obtained values are compared to published data available for the given temperatures. It is shown that the temperature dependencies of the partition coefficients K ( T ) , the diffusion lengths L D ( T ) , and the permeabilities P ( T ) could be described analytically for the studied temperature range 5-31 °C. This allows estimation of these quantities in the given temperature range and quantitative description of the transport of radon in the studied polymers.

Experimental study of the effect of water level and wind speed on radon exhalation of uranium tailings from heap leaching uranium mines.

Water level and wind speed have important influences on radon release in particle-packing emanation media. Based on radon migration theory in porous media under three water level conditions, an experimental setup was designed to measure the surface radon exhalation rate of uranium tailings from heap leaching uranium mine at different water levels and wind speeds. When the water level was at 0.3 m (overlying depth 0.05 m), radon transfer velocities at the gas-liquid interface were also measured at different wind speeds. Results show that when the water level was equal to or lower than the surface of the sample, the radon exhalation rate increased with increasing wind speed and decreased with increasing water level. When the water level was higher than the surface of the sample, radon exhalation rate of the water surface increased with increasing surface wind speed. The wind speed, however, was less influential on the radon exhalation rate as the depth of the overlying water increased, with a dramatic decrease in radon release. That said, at different wind speeds, radon transfer velocities at the gas-liquid interface were consistent with literature. On the other hand, changes in wind speed had significant influences on the radon transfer velocity at the gas-liquid interface, with the effect less pronounced at higher wind speeds.

Large-scale experimental investigations of specified granular fill materials for radon mitigation by active and passive soil depressurisations.

A series of large-scale experimental tests were performed to examine the flow behaviour of the T1 Struc and T2 Perm specified granular fill materials with active and passive depressurisations. Granular materials were compacted and tested at various compacted thicknesses. Compaction works were performed using a field compactor and compaction degrees of the materials were found to be higher than those induced by a standardised small-scale compactor. The air permeability (kah) values of the materials were obtained with active depressurisation. It was found that the overall trend of kah tended to decrease with the increase in the compacted thickness of the materials and were found to be compatible with those determined by the small-scale test apparatus. Results from passive depressurisation tests indicated that the rotating cowls performed the best, followed by a static open pipe and a pipe with a cap.

Experimental study on radon exhalation behavior of heap leaching uranium ore column with dilute sulfuric acid.

In order to study the radon release behavior when heap leaching uranium ores with dilute sulfuric acid, unleached uranium ores from a uranium mine in southern China were selected as test samples. Adopting parameters from leaching processes commonly used in uranium mines, a laboratory experiment was carried out for 21 days with a one-dimensional acid heap leaching experimental column. The surface radon exhalation rate of uranium ore column was determined by static accumulation method while spraying with deionized water and dilute sulfuric acid. The uranium leaching rate and ore column height for all 21 days of the experiment were also measured. The results show that (1) when sprayed with a leaching agent, the surface radon exhalation rate of uranium ore column initially increased with time sharply. After a maximum value was reached, the rate gradually decreased and stabilized. When the spraying stopped, the surface radon exhalation rate of uranium ore column initially decreased, before increasing until it tended to stabilize. (2) During the entirety of the 21-day leaching experiment, the cumulative leaching rate of uranium increased gradually with time. On the other hand, the surface radon exhalation rate of uranium ore column fluctuated, but the leaching of uranium from uranium ores had almost no effect on the radon exhalation rate. (3) There was no linear correlation between the surface radon exhalation rate and the residual height of ore column during leaching, but the collapsing event of ore column was the direct inducing factor of the fluctuation of surface radon exhalation rate.

Distribution of natural radionuclides and radon concentration in the riverine environs of Cauvery, South India.

Systematic studies were carried out to understand the distribution of natural radionuclides in sediments and radon in water in the riverine environs of Cauvery, one of the major rivers of South India. The activity of radionuclides in the sediment was measured by gamma ray spectrometry. The radon emanation from the sediment was measured by the sealed 'can technique' and the radon in the water was measured using the RAD-7 instrument. The mean values of 40 K, 226Ra, and 232Th in the sediment samples were found to be 297.3 ± 4.16 Bq kg-1, 75.1 ± 2.64 Bq kg-1, and 85.5 ± 2.62 Bq kg-1, respectively. The mean activity of radon, radon exhalation rate, and radium content were found to be 135.68 Bq m-3, 327.1 mBq m-1 h-1, and 133.03 mBq kg-1, respectively. The radon in the water ranged from 0.19 kBq m-3 to 1.40 kBq m-3. The hyper pure germanium gamma spectroscopy measured via 226Ra activity and the radon activity measured by the passive can technique showed good correlation. The mean value of radon in the water was within the internationally recommended level. The sediment was considered safe for the purpose of construction, except for some extreme values, and the water was deemed safe for drinking.

Geochemical Cycle of Radon and its Bioremediation Opportunity from Water Environment: A Review.

BACKGROUND: The waterborne or airborne radon causes carcinogenesis in the human bodies due to the continuous decay of α- and ß- particles. The health risks related to radioactive radon instigate to develop an advanced technology for its removal from the environment. There are two standard techniques, such as aeration and activated carbon filtration, available for its removal. However, both of them face different technological drawbacks resulting in the processes either inefficient or inappropriate for the purpose. CONCLUSION: There are several technologies utilizing either algae or microorganisms that could be useful in the bioremediation of radon. Some of the algae and microorganisms are examined and found to be tolerated and decontaminated various ionization radiations like α-, ß-, and γ- radiations. In a US patent, the microalgae Coccomyxa actinabiotis isolated from a nuclear facility showed the properties of bioremediation towards radionuclides. They overcome the physiological stress in the extreme environment for their growth due to the evolution under the prolonged influence of high energy radiation. Further, they are stimulated by the process of cloning, genetic transformations and adaptations for the purpose of enhancing the tolerance and decontamination power. Therefore, biotechnological researches have lots of prospects to remove radon from the water environment using algae and microorganisms.

Detailed effects of particle size and surface area on 222Rn emanation of a phosphate rock.

The dependency of radon emanation on soil texture was investigated using the closed chamber method. Ground phosphate rock with a large specific surface area was analyzed, and the presence of inner pores, as well as a high degree of roughness and heterogeneity in the phosphate particles, was found. The average radon emanation of the dry phosphate was 0.145 ± 0.016. The emanation coefficient was highest (0.169 ± 0.019) for the smallest particles (<25 µm), decreasing to a constant value (0.091 ± 0.014) for the larger particles (>210 µm). The reduction rate followed an inverse power law. As expected, a linear dependence between the emanation coefficient and the specific surface area was found, being lower than predicted for the large specific surface area. This was most likely due to an increase in the embedding effect of radon atoms in adjacent grains separated by micropores. Results indicate that knowledge of grain radium distribution is crucial to making accurate emanation predictions.

DEVELOPMENT OF THE CHARCOAL ADSORPTION TECHNIQUE FOR DETERMINATION OF RADON CONTENT IN NATURAL GAS.

A technique for the determination of the radon concentration in natural gas using charcoal adsorption has been developed to study the effects of parameters that influence the adsorption efficiency of radon onto activated charcoal. Several sets of experiments were conducted both in the laboratory and in an actual natural gas field for comparison. The results show that the adsorption capability of radon onto activated charcoal varies inversely with temperature, hydrocarbon concentration and the humidity contained within the natural gas. A technique utilizing dry ice as a coolant was found to be the most effective for trapping radon in natural gas samples at the production site. A desiccant can be used to remove moisture from the sampling gas. The technique described here increases the adsorption efficiency of activated charcoal by 10-20% compared to our previous study.

222Rn, 220Rn and Their Progenies Measured in the Air of Different Dwellings and Workplaces and Resulting Alpha Radiation Doses to the Eyes of Individuals.

In order to assess radiation doses to the eyes of individuals, concentrations of Rn, Rn and their decay products were measured in different dwelling rooms, café rooms and vehicle repair shops by using two different types of solid state nuclear track detectors (SSNTDs). The influence of building materials, pollution and ventilation rate on radon and thoron alpha-activities inside the studied locations has been investigated. A new dosimetric model was developed for evaluating radiation doses to the eyes of individuals due to alpha particles emitted by the radon and thoron series in the air of the studied dwelling rooms, café rooms, and vehicle repair shops. The influence of the radon and thoron activities in the air of the studied locations, as well as exposure time on committed equivalent dose to the eyes of individuals, was investigated. A maximum value of the committed equivalent dose to the eyes of individuals due to alpha particles emitted by the radon and thoron series was found equal to 0.1 mSv y cm. Committed equivalent dose to the eyes of individuals due to the diffusion of the Rn and Rn gases present in ambient air of the studied locations has been evaluated.

The experimental study on the emanation power of a flow-through thoron source made from incandescent gas mantles.

To improve the quality of the calibration of thoron concentration activity measurement, an experimental study on the emanation power of a flow-through thoron source based on incandescent gas mantles was carried out in this paper. The thoron activity concentrations of the outflowed air from the flow-through source were measured using RAD7, and the quantitative relationship between thoron concentrations and flowrates was studied through theoretical analysis, and the thoron emanation powers were obtained from the fitting of the relationship above. Results show that the thoron concentration decreased with the increasing flowrate in the gas path, and the thoron emanation powers of three batches of gas mantles obtained by fitting were 1.33% ± 0.17%, 0.77% ± 0.10% and 0.57% ± 0.07% respectively in low humidity condition. Those results were checked using the gamma spectroscopy method, and were consistent within the error range.

100 Years of Radiation Research in the Footsteps of Failla.

Gioacchino Failla was initially appointed to operate the radon plant at Memorial Hospital in 1916. What to most people would have been a part-time temporary position was to him a career. He was not satisfied to simply fabricate radon seeds, he wanted to understand the physics and biology of the radiation emitted by the progeny of radium. His was not the first medical physics group in the United States, though it was one of the earliest, but it was the first to put such emphasis on the biological effects. After more than 28 years at Memorial Hospital, Failla moved his research group to Columbia University Medical Center and his pioneering work, blending physics and biology, has continued to date at Columbia by those that he trained or inspired, under three directors that followed him.

Geographical Correlations between Indoor Radon Concentration and Risks of Lung Cancer, Non-Hodgkin's Lymphoma, and Leukemia during 1999-2008 in Korea.

Indoor radon is the second most important risk factor for lung cancer and may also be a risk factor for hematopoietic cancers, particularly in children and adolescents. The present study measured indoor radon concentration nationwide at 5553 points during 1989-2009 and spatially interpolated using lognormal kriging. The incidences of lung cancer, non-Hodgkin's lymphoma (NHL), and leukemia, stratified by sex and five-year age groups in each of the 234 administrative regions in the country during 1999-2008, were obtained from the National Cancer Registry and used to calculate the standardized incidence ratios. After considering regional deprivation index values and smoking rates by sex in each region as confounding variables, the cancer risks were estimated based on Bayesian hierarchical modeling. We found that a 10 Bq/m³ increase in indoor radon concentration was associated with a 1% increase in the incidence of lung cancer in male and a 7% increase in NHL in female children and adolescents in Korea aged less than 20 years. Leukemia was not associated with indoor radon concentration. The increase in NHL risk among young women requires confirmation in future studies, and the radon control program should consider children and adolescents.

Development of a preclinical 211Rn/211At generator system for targeted alpha therapy research with 211At.

INTRODUCTION: The availability of 211At for targeted alpha therapy research can be increased by the 211Rn/211At generator system, whereby 211At is produced by 211Rn electron capture decay. This study demonstrated the feasibility of using generator-produced 211At to label monoclonal antibody (BC8, anti-human CD45) for preclinical use, following isolation from the 207Po contamination also produced by these generators (by 211Rn α-decay). METHODS: 211Rn was produced by 211Fr electron capture decay following mass separated ion beam implantation and chemically isolated in liquid alkane hydrocarbon (dodecane). 211At produced by the resulting 211Rn source was extracted in strong base (2N NaOH) and purified by granular Te columns. BC8-B10 (antibody conjugated with closo-decaborate(2-)) was labeled with generator-produced 211At and purified by PD-10 columns. RESULTS: Aqueous solutions extracted from the generator were found to contain 211At and 207Po, isolated from 211Rn. High radionuclidic purity was obtained for 211At eluted from Te columns, from which BC8-B10 monoclonal antibody was successfully labeled. If not removed, 207Po was found to significantly contaminate the final 211At-BC8-B10 product. High yield efficiencies (decay-corrected, n=3) were achieved for 211At extraction from the generator (86%±7%), Te column purification (70%±10%), and antibody labeling (76%±2%). CONCLUSIONS: The experimental 211Rn/211At generator was shown to be well-suited for preclinical 211At-based research. ADVANCES IN KNOWLEDGE: We believe that these experiments have furthered the knowledge-base for expanding accessibility to 211At using the 211Rn/211At generator system. IMPLICATIONS FOR PATIENT CARE: As established by this work, the 211Rn/211At generator has the capability of facilitating preclinical evaluations of 211At-based therapies.

211Rn/211At and 209At production with intense mass separated Fr ion beams for preclinical 211At-based α-therapy research.

Mass-separated francium beams (211Fr or 213Fr) were implanted into solid targets for producing 211Rn (14.6h half-life) or 209At (5.41h), in situ. 211Rn was transferred to dodecane and isolated from contaminants, providing sources for 211At (7.21h) production by 211Rn decay (73%). 209At was recovered with high radionuclidic purity in aqueous solutions, directly. These experiments demonstrated Fr beam implantations as a novel method for producing preclinical quantities of 211Rn/211At (for therapy) and 209At (for imaging).

Radon Release and Its Simulated Effect on Radiation Doses.

One of the main factors that affect the uncertainty in calculating the gamma-radiation absorbed dose rate inside a room is the variation in the degree of secular equilibrium of the considered radioactive series. A component of this factor, considered in this paper, is the release of radon (Rn) from building materials to the living space of the room. This release takes place through different steps. These steps are represented and mathematically formulated. The diffusion of radon inside the material is described by Fick's second law. Some of the factors affecting the radon release rate (e.g. covering walls, moisture, structure of the building materials, etc.) are discussed. This scheme is used to study the impact of radon release on the gamma-radiation absorbed dose rate inside a room. The investigation is carried out by exploiting the MCNP simulation software. Different building materials are considered with different radon release rates. Special care is given to Rn due to its relatively higher half-life and higher indoor concentration than the other radon isotopes. The results of the presented model show that the radon release is of a significant impact in some building materials.

Assessment of indoor radon, thoron concentrations, and their relationship with seasonal variation and geology of Udhampur district, Jammu & Kashmir, India.

Background The inhalation doses resulting from the exposure to radon, thoron, and their progeny are important quantities in estimating the radiation risk for epidemiological studies as the average global annual effective dose due to radon and its progeny is 1.3 mSv as compared to that of 2.4 mSv due to all other natural sources of ionizing radiation. Objectives The annual inhalation dose has been assessed with an aim of investigating the health risk to the inhabitants of the studied region. Methods Time integrated deposition based 222Rn/220Rn sensors have been used to measure concentrations in 146 dwellings of Udhampur district, Jammu and Kashmir. An active smart RnDuo monitor has also been used for comparison purposes. Results The range of indoor radon/thoron concentrations is found to vary from 11 to 58 Bqm-3 with an average value of 29 ± 9 Bqm-3 and from 25 to 185 Bqm-3 with an average value of 83 ± 32 Bqm-3, respectively. About 10.7% dwellings have higher values than world average of 40 Bqm-3 prescribed by UNSCEAR. The relationship of indoor radon and thoron levels with different seasons, ventilation conditions, and different geological formations have been discussed. Conclusions The observed values of concentrations and average annual effective dose due to radon, thoron, and its progeny in the study area have been found to be below the recommended level of ICRP. The observed concentrations of 222Rn and 220Rn measured with active and passive techniques are found to be in good agreement.