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Waste from resource extraction industries contains uranium and thorium decay chain radionuclides. One important radiological impact of these wastes is the release of radon into the atmosphere. Therefore, the prediction/evaluation of radon flux and the effectiveness of different covers are the major elements in radiation protection, long-term safety aspects, and the modeling of radon release into the environment for a final assessment of radiological impacts and required remediation actions. A measurement system has been designed based on the transient-diffusion method to evaluate radon exhalation by the short-time accumulation technique. The validity of the laboratory model to quickly estimate the radon release from soils, the diffusion coefficient, and the effect of covers was investigated. From the results obtained from the experimental model, it was observed that after a 0.5-m(1-m) cover layer, the radon flux reduction factor increases from 1.3(2.1) for sand to about 2(3) for clay. The results show that the effectiveness of the cover layer studied is 3, which is similar to theoretical and experimental results in uranium tailings ponds. [ABSTRACT FROM AUTHOR]

Indoor radon is one of the most significant contributors to lung cancer after smoking. Mitigation strategies based on protecting buildings with radon barrier materials, combined with home ventilation or room pressurization, are regularly used. A scale model room made from a porous ignimbrite rich in radon precursors was used as an analogue to test the efficiency of fifteen airtight membranes to reduce radon levels, also in combination with room pressurization. The results of these experiments were considered together with previous ones to propose the scale model room approach as a tool for rapidly evaluating the performance of specially designed radon barrier materials, and for radiation exposure assessment. Relative reduction of indoor radon (RIR) ranges from −20 to −94%. The most effective materials were FPO membrane, single-component silane-terminated polymer membranes and synthetic resins. The presence of additives likely modified the composition and structure of some products, improving their radon barrier capacity. The introduction of room pressurization further reduced radon levels in the model room where the membranes were applied. The overpressure necessary to reach RIRs of the order of 85–90% is very low for materials that powerfully stop radon even without ventilation, but necessarily higher for poorer membranes. [ABSTRACT FROM AUTHOR]

Indoor radon is one of the most significant contributors to lung cancer after smoking. Mitigation strategies based on protecting buildings with radon barrier materials, combined with home ventilation or room pressurization, are regularly used. A scale model room made from a porous ignimbrite rich in radon precursors was used as an analogue to test the efficiency of fifteen airtight membranes to reduce radon levels, also in combination with room pressurization. The results of these experiments were considered together with previous ones to propose the scale model room approach as a tool for rapidly evaluating the performance of specially designed radon barrier materials, and for radiation exposure assessment. Relative reduction of indoor radon (RIR) ranges from −20 to −94%. The most effective materials were FPO membrane, single-component silane-terminated polymer membranes and synthetic resins. The presence of additives likely modified the composition and structure of some products, improving their radon barrier capacity. The introduction of room pressurization further reduced radon levels in the model room where the membranes were applied. The overpressure necessary to reach RIRs of the order of 85–90% is very low for materials that powerfully stop radon even without ventilation, but necessarily higher for poorer membranes.

Radon is the second leading risk factor for lung cancer after smoking. As a public policy, radon mitigation not only involves radon control technology or its cost-benefit analysis, but also includes the decision-making process of local governments. In this study, the evolutionary game theory was used to analyse the interaction between local governments and residents based on the subsidy of the central government. Considering the practical data in China, factors influencing the behaviour of local governments and residents were discussed using numerical simulations. The results indicated that radon mitigation is a fully government-promoted action; thus, its implementation largely depends on the subsidy of the central government and the share of radon control costs borne by the local government. The financial burden for both local governments and residents is a more important determinant than long-term health effects. The relatively poor local economic situation could limit the implementation of radon control. There would be a public policy paradox wherein cities or regions with higher radon risk would have lower willingness for radon control, mainly due to the significantly higher costs of radon control. This work provides reference data for decision-making to implement radon control and is expected to offer some suggestions for local governments.

Indoor radon is the second cause of lung cancer. Mitigation strategies are based on (i) building protection with radon barrier materials, (ii) increasing home ventilation or (iii) room pressurization. A scale model room created with a porous ignimbrite rich in radon precursors was used as an analogue to test the indoor radon reduction ability of various radon barrier materials in a real room. The properties of these materials were tested with and without room pressurization by introducing outdoor air at different flow rates. The best materials reduced indoor radon up to 80% and, when the highest pressurization was applied, to 93%. [ABSTRACT FROM AUTHOR]

Canada has significant radon issues due to the underlying geology, extreme climate, and building construction. Canadians love the outdoors and value clean fresh air, but the indoor environment has the potential for high levels of radon in both homes and workplaces. However, Canada has robust programs in place to raise radon awareness, train radon professionals, and effectively reduce radon levels in all types of buildings. [ABSTRACT FROM AUTHOR]

Indoor radon is the second cause of lung cancer. Mitigation strategies are based on (i) building protection with radon barrier materials, (ii) increasing home ventilation or (iii) room pressurization. A scale model room created with a porous ignimbrite rich in radon precursors was used as an analogue to test the indoor radon reduction ability of various radon barrier materials in a real room. The properties of these materials were tested with and without room pressurization by introducing outdoor air at different flow rates. The best materials reduced indoor radon up to 80% and, when the highest pressurization was applied, to 93%.

The effectiveness of the increase in passive ventilation was studied as remedial action for high concentrations of indoor radon gas activity. The rationale has been to apply the provisions of Directive 2013/59/EURATOM, partially implemented by a regional law of Puglia Region (Southern Italy). Residential buildings were selected based on characteristics common to those of commercial premises, which are the recipients of legislative obligations. The final goal of this study was to evaluate the feasibility of carrying out the same remediation activity for both types of buildings. From a previous survey in Puglia in 2013–2014, 18 houses were selected and passive ventilation strategy was applied in order to evaluate its effect on the radon activity concentration. A specially designed protocol defined frequency and time of windows operation. The average value of the annual measurement revealed a significant reduction of the internal radon activity concentration: mitigation ranged from 21 ± 5% to 58 ± 2% with an average value of 33 ± 3%. The results of the study showed that passive ventilation is an effective method of mitigation of the internal radon concentration if correctly designed according to the local characteristics of the buildings and habits of the occupants. [ABSTRACT FROM AUTHOR]

In the near future, research on new materials for radon barriers can be expected to rise in order to meet a greater demand of radon mitigation solutions because of the increasingly lower radon levels that the EU legislation aims to. Such research would need a method for the determination of the radon diffusion coefficient and this paper presents an inexpensive method for that purpose, using affordable radon detectors and a simple experimental setup that does not require any tubing or any pumping. Besides the use of two Electronic Integration Devices as radon detectors, the experimental setup used in our method consists only in a two-chamber container made of steel and a small-sized radon source, which was produced in our lab using a 226Ra solution. The radon diffusion coefficient is determined by measuring radon levels in both chambers of the container, which are separated by a membrane made of the material whose radon diffusion coefficient is to be determined. Radon diffuses from a source chamber to a receiver chamber trough the membrane, being the amount of radon that has passed through and the rate at which it has done so the key parameters in the calculation of the radon diffusion coefficient. Our method can handily measure materials with a radon diffusion coefficient above or equal to 10-11 m2 s-1 or, provided that the sample is thin enough, verify that the coefficient is lower than 10-12 m2 s-1. Its precision is good enough to provide radon coefficient diffusion values with a good repeatability as the RSD is as low as a 35% for materials in which the coefficient is in the order of 10-11 m2 s-1. This means that our method is valid for screening materials for radon barriers and checking their compliance with technical specifications. [Display omitted] • New and inexpensive method for the determination of the radon diffusion coefficient, using a simple experimental setup. • Two Electronic Integration Devices are used as radon detectors inside an airtight container, with a small-sized radon source. • This method can measure materials with low radon diffusion coefficients, allowing the screening materials for radon barriers. [ABSTRACT FROM AUTHOR]

Abstract Radon is a gas produced from the radioactive natural disintegration of radium and uranium, which is present in soils and different building materials. Due to its gaseous nature, it emanates to the surface and penetrates both by convection and diffusion into the houses. According to recent studies, radon is considered the second leading cause of lung cancer, and it has prompted legislative changes to reduce exposure to this gas. In Spain, the current legislation -R.D. 783/2001 Regulation on Sanitary Radiation Protection and IS-33 Instruction of the Nuclear Safety Council, establishes uniform rules for workers' health protection in radioactive installations. In 2013, the European legislation was updated with Directive 2013/59/EURATOM which sets limit values and action plans for radon exposure for homes, public buildings and workplaces for any entrance roads (soil, building materials or water). This Directive must be incorporated before 18th February 2018 into Spanish legislation, so it is necessary to perform, prior to that date, appropriate protocol techniques and methodologies for the measurement radon concentrations in air. This work aims at a preventive approach to the situation. That is, to measure the concentration levels of radon exhaled prior to the design and construction of the dwellings to avoid their accumulation inside The main purpose of this work is the comparison of different radon exhalation measurement techniques in order to define the most appropriate methodology in different cases for the implementation of the new radon control Directive. Highlights • The Directive 59/EURATOM must be incorporated before 18th February 2018 into Spanish legislation. • The main purpose of this work is the comparison of different techniques of radon exhalation measurement. • The most appropriate methodology for radon exhalation measurement is defined. [ABSTRACT FROM AUTHOR]

Abstract Activated charcoal was widely used in radon researches and mitigation applications because of good adsorption ability. In the paper, a simple model that can predict radon removal efficiency (η) for radon mitigation applications using flow-through activated charcoal system was developed based on the previous works. Experiments were conducted with a flow-through activated charcoal system to validate the model and study the influence of factors on η. The experimental results of η are consistent with the theory to within 4% at the flow rates of 1–3 L/min, but range from 2% to 14% at the flow rates of 4–5 L/min. The equilibrium time of radon linearly decreases with rising flow rate, and η decreases with rising flow rate. With moisture competing with radon for adsorption sites on the activated charcoal, radon reaches the equilibrium concentration more quickly than moisture does. As relative humidity increases, η decreases, but the radon equilibrium concentration increases. The values of η are bigger for those smaller particle sizes with the same type of activated charcoal. The results of this paper are useful for designing activated charcoal systems at indoor environmental conditions and predicting η for radon mitigation applications. Highlights • Prediction of radon removal efficiency for radon mitigation applications with activated charcoal systems. • Characteristics of radon mitigation for the flow-through activated charcoal system. • Evaluation of the effectiveness of radon mitigation for activated charcoal systems. • Enables future application to design activated charcoal systems for radon mitigation. [ABSTRACT FROM AUTHOR]

Radon is the second leading risk factor for lung cancer after smoking. As a public policy, radon mitigation not only involves radon control technology or its cost-benefit analysis, but also includes the decision-making process of local governments. In this study, the evolutionary game theory was used to analyse the interaction between local governments and residents based on the subsidy of the central government. Considering the practical data in China, factors influencing the behaviour of local governments and residents were discussed using numerical simulations. The results indicated that radon mitigation is a fully government-promoted action; thus, its implementation largely depends on the subsidy of the central government and the share of radon control costs borne by the local government. The financial burden for both local governments and residents is a more important determinant than long-term health effects. The relatively poor local economic situation could limit the implementation of radon control. There would be a public policy paradox wherein cities or regions with higher radon risk would have lower willingness for radon control, mainly due to the significantly higher costs of radon control. This work provides reference data for decision-making to implement radon control and is expected to offer some suggestions for local governments., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier Ltd.)

Design of bearing layers (granular fill material layers) is important for a house with a soil depressurisation (SD) system for indoor radon mitigation. These layers should not only satisfy the bearing capacity and serviceability criteria but should also provide a sufficient degree of the air permeability for the system. Previous studies have shown that a critical parameter for a SD system is the sub-slab pressure field extension in the bearing layers, but this issue has not been systematically investigated. A series of two-dimensional computational fluid dynamic simulations that investigate the behaviour of the sub-slab pressure field extension developed in a SD system is presented in this paper. The SD system considered in this paper consists of a granular fill material layer and a radon sump. The granular fill materials are ‘T1 Struc’ and ‘T2 Perm’, which are standard materials for building in the Republic of Ireland. Different conditions, which might be encountered in a practical situation, were examined. The results show that the air permeability and thickness of the granular fill materials are the two key factors which affect the sub slab pressure field extension (SPFE) significantly. Furthermore, the air permeability of native soil is found to be a fundamental factor for the SPFE so that it should be well understood when designing a SD system. Therefore, these factors should be considered sufficiently in each practical situation. Finally, a significant improvement of the pressure field extension can be achieved by ensuring air tightness of the SD system. [ABSTRACT FROM AUTHOR]

Abstract The noble elements, argon and xenon, are frequently employed as the target and event detector for weakly interacting particles such as neutrinos and Dark Matter. For such rare processes, background radiation must be carefully minimized. Radon provides one of the most significant contaminants since it is an inevitable product of trace amounts of natural uranium. To design a purification system for reducing such contamination, the adsorption characteristics of radon in nitrogen, argon, and xenon carrier gases on various types of charcoals with different adsorbing properties and intrinsic radioactive purities have been studied in the temperature range of 190–295 K at flow rates of 0.5 and 2 standard liters per minute. Essential performance parameters for the various charcoals include the average breakthrough times (τ), dynamic adsorption coefficients (k a) and the number of theoretical stages (n). It is shown that the k a -values for radon in nitrogen, argon, and xenon increase as the temperature of the charcoal traps decreases, and that they are significantly larger in nitrogen and argon than in xenon gas due to adsorption saturation effects. It is found that, unlike in xenon, the dynamic adsorption coefficients for radon in nitrogen and argon strictly obey the Arrhenius law. The experimental results strongly indicate that nitric acid etched Saratech is the best candidate among all used charcoal brands. It allows reducing total radon concentration in the LZ liquid Xe detector to meet the ultimate goal in the search for Dark Matter. [ABSTRACT FROM AUTHOR]

In a bounded open subset Ω ⊂ R n , we study Dirichlet problems with elliptic systems, involving a finite Radon measure μ on R n with values into R N , defined by { − div A ( x , u ( x ) , D u ( x ) ) = μ in Ω , u = 0 on ∂ Ω , where A i α ( x , y , ξ ) = ∑ β = 1 N ∑ j = 1 n a i , j α , β ( x , y ) ξ j β with α ∈ { 1 , … , N } the equation index. We prove the existence of a (distributional) solution u : Ω → R N , obtained as the limit of approximations, by assuming: (i) that coefficients a i , j α , β are bounded Carathéodory functions; (ii) ellipticity of the diagonal coefficients a i , j α , α ; and (iii) smallness of the quadratic form associated to the off-diagonal coefficients a i , j α , β (i.e. α ≠ β ) verifying a r -staircase support condition with r > 0 . Such a smallness condition is satisfied, for instance, in each one of these cases: (a) a i , j α , β = − a j , i β , α (skew-symmetry); (b) | a α , β i , j | is small; (c) a i , j α , β may be decomposed into two parts, the first enjoying skew-symmetry and the second being small in absolute value. We give an example that satisfies our hypotheses but does not satisfy assumptions introduced in previous works. A Brezis's type nonexistence result is also given for general (smooth) elliptic-hyperbolic systems. [ABSTRACT FROM AUTHOR]

A series of experimental laboratory tests were conducted to quantitatively investigate the characterisation of the T1 Struc and T2 Perm specified granular fill materials for soil depressurisation systems for radon reduction under buildings. The characterisation included determination of grading curves, measurement of air permeability, porosity, and the effective particle diameter of the stone. A test apparatus was developed to measure the air permeability of the granular fill materials under different compaction degrees. Test results showed that the T1 Struc and T2 Perm specified granular fill materials could be classified as well-graded and poorly-graded granular materials, respectively. The air permeability and porosity of T1 Struc decrease with the increase in compaction degree and are strongly affected by the change of moisture content. However, the air permeability of T2 Perm was found to be independent of the compaction degree and variation of moisture content. Computational Fluid Dynamic (CFD) simulations were validated to simulate the flow behaviour of the T1 Struc and T2 Perm granular fill materials. The primary parameters for simulating the flow behaviour of the materials were confirmed to be the air permeability, porosity, and effective particle diameter. Based on the CFD simulation results, the effective particle diameter was found to vary with the compaction degree for T1 Struc , whereas that of T2 Perm was constant at 16.2 mm. [ABSTRACT FROM AUTHOR]

In order to ensure good living standards, all risk factors are considered in ensuring work and life conditions. The urban lives we live can be influenced by the quality of air both at work and at home. Amongst environmental factors, air is essential to a good quality of life. A component that demands close supervision is the radioactive gas Radon. It originates both from natural radioactive constituents of Earth's crust and construction materials. This introduces variety to the places where Radon is found, both in terms of local geological structure as well as building characteristics. Radon concentration levels in inhabited buildings can also be influenced by the tenant's daily habits. Both the presence and measures of reducing the concentration of this radioactive gas require its monitoring. The adoption of EU directive 2013/59/Euratom draw attention on protection of the population and working personnel at Radon exposure, in buildings with public access and workplaces, from any source of Radon infiltration, whether originating from the ground and/or from construction materials. The Radioecology Laboratory INCDM "Grigore Antipa" - Constanta initiated a program of methodological testing and annual Radon monitoring. Preliminary results of Radon concentration measurements through an active method range from 10-429 Bq/m3 (Fig. 1). Constant supervision is maintained in order to consolidate observations of Rn concentration variation over time, as a function of meteorological parameters, this potentially serving as a benchmark for measurements in coastal areas. [ABSTRACT FROM AUTHOR]

In this paper, we are treating the results of radon concentration in soil gas, which are obtained by a detailed study carried out during 2000-2005 years in the urban area of Tirana, Capital City of Albania. The field measurements were done by using Luk-4 equipment (Lucas method) and based on technique [12, 18-20, 21-24]. Based on the analysis of the data taken by this research, was concluded that the level of the radon concentration in soil gas of Tirana urban area depends on the soil type. The highest level of radon gas (130.0 kBqm-3) was observed in inorganic clays and very fine sands with beige-red color (soils type 1), which is extended on the second terrace of Tirana River. This paper gives conclusions of soil gas radon concentration, where its value ranges from 0.9-1.54 kBqm-3 up to 92.03-130.0 kBqm-3. The results indicate that more than 50% of Tirana urban area is made of soils, which are characterized by high soil radon gas concentration, which constitutes a real risk for the Tirana's residents. [ABSTRACT FROM AUTHOR]

This study was aimed to calculate the radon gas emitted from inner walls of buildings using twenty-six different paint types of different origin (Iraq, Jordan, Turkey, Greece, Norway, Egypt, Germany, United States and Emirates) for environmental protection. The Radon-Scout detector was placed in a plastic container and placed at painted wall samples. The range of radon exposure was between 9±1 and 57 ± 4 Bq • m-3. Radon exposures decreased to +74% when they were measured in terms of radon shield percentage (RSP). Radon exposures increased when the RSP dropped to -68%. This study concluded that the relationship between radon concentration and RSP depends on the type and structure of paints used. [ABSTRACT FROM AUTHOR]

Ingesting waters holding high levels of natural occurring radioactive element like Radon would contribute to increase in the effective dose received by people followed by an increased prevalence of cancer. The current study is an attempt to describe the extent of contribution of222Rn to natural background radiation and the resultant effective dose to public of different age groups. In order to do so, 65 groundwater samples from selected parts of Bangalore city were collected and analyzed for radon activity using RAD7 radon monitor coupled with RAD H2O accessories. The radon activity was in the range of 3.05–696 Bq/L (mean: 91.39 Bq/L) and 92.31% of the groundwater samples recorded elevated radon concentration above the United States environmental protection agency (USEPA's) Maximum Contaminant Level (MCL) value of 300 pCi/L, corresponding to 11.1 Bq/L. The mean annual effective dose contribution of people falling under different age groups (viz., infants, children, teens: males and females, adults: males and females, pregnant and lactating women) due to ingestion of water-borne222Rn ranged from 0.082 to 0.444 mSv/y and was found to be higher in all the age groups of males compared to respective female age groups, but well within the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and World Health Organization (WHO) proposed limit of 1 mSv/y. [ABSTRACT FROM PUBLISHER]

Exposure to radon gas is the second leading cause of lung cancer worldwide. Radon can accumulate unnoticed within buildings, so it is vital that properties at risk are tested and action is taken to reduce high concentrations where present. Many people remain unaware of radon and only learn about it when purchasing a property, as it is covered in various conveyance documents. High radon levels in existing buildings can be mitigated and new properties can be protected from radon intrusion with careful design and workmanship. This paper discusses why it is important to protect people from radon exposure, the laws that exist to limit exposure in certain situations and the methods that can be employed in both existing and newbuilds to do so. The impact of modern energy-efficient building designs is also addressed. [ABSTRACT FROM AUTHOR]

We analyze in this paper a Waste Water Pre-Treatment Plant (WWTP) located at the Mediterranean coast with air radon concentration above Spanish action level (600 Bq per cubic meter). This paper presents a method for radon equilibrium determination by gamma spectrometry measuring of the radon progeny concentrations in the air, in order to estimate WWTP workers effective dose more exactly. The method is based on simultaneous sampling of air through a filter paper and alpha spectrometry measurement of radon activity concentration in the air. According to the measured radon activity concentration in the air of 368±45 Bq/m 3 the equilibrium factor between radon and progenies is estimated to be F=0.27, which is in good agreement with expected values. [ABSTRACT FROM AUTHOR]

A number of international health organizations consider the exposure to residential radon as the second main cause of lung cancer after cigarette smoking. For this, it was found that there is no data base on radon concentrations for the Kufa Technical Institute buildings in literature. This therefore triggers a special need for radon measurement in some Kufa Technical Institute buildings. This study aims to investigate the indoor radon levels inside the Kufa Technical Institute buildings for the first time using different radon measurement methods such as active (RAD-7) and passive methods (LR-115 Type II). Seventy eight of Solid-State Nuclear Track Detectors (SSNTDs) LR-115 Type II was distributed at four buildings within the study area. The LR-115 Type II detectors were exposed in the study area for three months period. In parallel to the latter, seventy two active measurements were conducted using RAD-7 in the same buildings for correlation investigation purposes between the two kinds of measurements (i.e. passive and active).The results demonstrate that the radon concentrations were generally low, which are ranging from 38.4 to 77.2 Bq/m3, with a mean value of 50 Bq/m3. The mean of the equilibrium equivalent radon concentration and annual effective dose were assessed to be 19.9 Bq/m3 and 1.2 mS/y respectively; the excess lifetime lung cancer risk was approximately 11.6 per million personal. A high correlation was found between the methods of measurements (i.e. LR-115 Type II and RAD-7), R2 = 0.99 which is significant at P < 0.001. The results of this work revealed that that Radon concentration was below the action level set by the United States Environmental Protection Agency of 148 Bq/m3. This therefore indicates that no radiological health hazard exists. However, the relatively high concentrations in some classrooms can be addressed by the natural ventilation or the classrooms being supplied with suction fans. [ABSTRACT FROM AUTHOR]

This study was conducted to provide fundamental data on the distribution of radon concentrations in child day-care facilities in South Korea and to help establish radon mitigation strategies. For this study, 230 child-care centers were randomly chosen from all child-care centers nationwide, and alpha track detectors were used to examine cumulative radon exposure concentrations from January to May 2015. The mean radon concentration measured in Korean child-care centers is approximately 52 Bq m −3 , about one-third of the upper limit of 148 Bq m −3 , which is recommended by South Korea's Indoor Air Quality Control in Public Use Facilities, etc. Act and the U.S. Environmental Protection Agency (EPA). Furthermore, this concentration is about 50% lower than 102 Bq m −3 , which is the measured concentration of radon in houses nationwide from December 2013 to February 2014. Our results indicate that the amount of ventilation, as a major determining factor for indoor radon concentrations, is strongly correlated with the fluctuation of indoor radon concentrations in Korean child-care centers. [ABSTRACT FROM AUTHOR]

In many countries, assessment programmes are carried out to identify areas where people may be exposed to high radon levels. These programmes often involve detailed mapping, followed by spatial interpolation and extrapolation of the results based on the correlation of indoor radon values with other parameters (e.g., lithology, permeability and airborne total gamma radiation) to optimise the radon hazard maps at the municipal and/or regional scale. In the present work, Geographical Weighted Regression and geostatistics are used to estimate the Geogenic Radon Potential (GRP) of the Lazio Region, assuming that the radon risk only depends on the geological and environmental characteristics of the study area. A wide geodatabase has been organised including about 8000 samples of soil-gas radon, as well as other proxy variables, such as radium and uranium content of homogeneous geological units, rock permeability, and faults and topography often associated with radon production/migration in the shallow environment. All these data have been processed in a Geographic Information System (GIS) using geospatial analysis and geostatistics to produce base thematic maps in a 1000 m x 1000 m grid format. Global Ordinary Least Squared (OLS) regression and local GeographicalWeighted Regression (GWR) have been applied and compared assuming that the relationships between radon activities and the environmental variables are not spatially stationary, but vary locally according to the GRP. The spatial regression model has been elaborated considering soil-gas radon concentrations as the response variable and developing proxy variables as predictors through the use of a training dataset. Then a validation procedure was used to predict soil-gas radon values using a test dataset. Finally, the predicted values were interpolated using the kriging algorithm to obtain the GRP map of the Lazio region. The map shows some high GRP areas corresponding to the volcanic terrains (central-northern sector of Lazio region) and to faulted and fractured carbonate rocks (central-southern and eastern sectors of the Lazio region). This typical local variability of autocorrelated phenomena can only be taken into account by using local methods for spatial data analysis. The constructed GRP map can be a useful tool to implement radon policies at both the national and local levels, providing critical data for land use and planning purposes. [ABSTRACT FROM AUTHOR]

Radon exposure is considered to cause several hundred fatalities from lung-cancer each year in Norway. A national map identifying areas which are likely to be exposed to elevated radon concentrations would be a useful tool for decision-making authorities, and would be particularly important in areas where only few indoor radon measurements exist. An earlier Norwegian study (Smethurst et al. 2008) produced radon hazard maps by examining the relationship between airborne gamma-ray spectrometry, bedrock and drift geology, and indoor radon. The study was limited to the Oslo region where substantial indoor radon and airborne equivalent uranium datasets were available, and did not attempt to test the statistical significance of relationships, or to quantify the confidence of its predictions. While it can be anticipated that airborne measurements may have useful predictive power for indoor radon, airborne measurement coverage in Norway is at present sparse; to provide national coverage of radon hazard estimates, a good understanding of the relationship between geology and indoor radon is therefore important. In this work we use a new enlarged (n ¼ 34,563) form of the indoor radon dataset with national coverage, and we use it to examine the relationship between geology and indoor radon concentrations. We use this relationship to characterise geological classes by their radon potential, and we produce a national radon hazard map which includes confidence limits on the likelihood of areas having elevated radon concentrations, and which covers the whole of mainland Norway, even areas where little or no indoor radon data are available. We find that bedrock and drift geology classes can account for around 40% of the total observed variation in radon potential. We test geology-based predictions of RP (radon potential) against locally-derived estimates of RP, and produce classification matrices with kappa values in the range 0.37 e0.56. Our classifier has high predictive value but suffers from low sensitivities for radon affected areas. We investigate an alternative classification method based on a Naïve Bayes classifier which results in similar overall performance. The work forms part of an ongoing study which will eventually incorporate airborne equivalent uranium data, as and when new airborne data become available. [ABSTRACT FROM AUTHOR]

It is estimated that exposure to radon in Norwegian dwellings is responsible for as many as 300 deaths a year due to lung cancer. To address this, the authorities in Norway have developed a national action plan that has the aim of reducing exposure to radon in Norway (Norwegian Ministries, 2010). The plan includes further investigation of the relationship between radon hazard and geological conditions, and development of map-based tools for assessing the large spatial variation in radon hazard levels across Norway. The main focus of the present contribution is to describe how we generate map predictions of radon potential (RP), a measure of radon hazard, from available airborne gamma ray spectrometry (AGRS) surveys in Norway, and what impact these map predictions can be expected to have on radon protection work including land-use planning and targeted surveying. We have compiled 11 contiguous AGRS surveys centred on the most populated part of Norway around Oslo to produce an equivalent uranium map measuring 180 km x 102 km that represents the relative concentrations of radon in the near surface of the ground with a spatial resolution in the 100 s of metres. We find that this map of radon in the ground offers a far more detailed and reliable picture of the distribution of radon in the sub-surface than can be deduced from the available digital geology maps. We tested the performances of digital geology and AGRS data as predictors of RP. We find that digital geology explains approximately 40% of the observed variance in ln RP nationally, while the AGRS data in the Oslo area split into 14 bands explains approximately 70% of the variance in the same parameter. We also notice that there are too few indoor data to characterise all geological settings in Norway which leaves areas in the geology-based RP map in the Oslo area, and elsewhere, unclassified. The AGRS RP map is derived from fewer classes, all characterised by more than 30 indoor measurements, and the corresponding RP map of the Oslo area has no unclassified parts. We used statistics of proportions to add 95% confidence limits to estimates of RP on our predictive maps, offering public health strategists an objective measure of uncertainty in the model. The geological and AGRS RP maps were further compared in terms of their performances in correctly classifying local areas known to be radon affected and less affected. Both maps were accurate in their predictions; however the AGRS map out-performed the geology map in its ability to offer confident predictions of RP for all of the local areas tested. We compared the AGRS RP map with the 2015 distribution of population in the Oslo area to determine the likely impact of radon contamination on the population. 11.4% of the population currently reside in the area classified as radon affected. 34% of ground floor living spaces in this affected area are expected to exceed the maximum limit of 200 Bq/m3, while 8.4% of similar spaces outside the affected area exceed this same limit, indicating that the map is very efficient at separating areas with quite different radon contamination profiles. The usefulness of the AGRS RP map in guiding new indoor radon surveys in the Oslo area was also examined. It is shown that indoor measuring programmes targeted on elevated RP areas could be as much as 6 times more efficient at identifying ground floor living spaces above the radon action level compared with surveys based on a random sampling strategy. Also, targeted measuring using the AGRS RP map as a guide makes it practical to search for the worst affected homes in the Oslo area: 10% of the incidences of very high radon contamination in ground floor living spaces (⩾800 Bq/m3) are concentrated in just 1.2% of the populated part of the area. [ABSTRACT FROM AUTHOR]

Precise radon measurements are a requirement for various applications, ranging from radiation protection over environmental studies to material screening campaigns for rare-event searches. All of them ultimately depend on the availability of calibration sources with a known and stable radon emanation rate. A new approach to produce clean and dry radon sources by implantation of 226Ra ions into stainless steel has been investigated. In a proof of principle study, two stainless steel plates have been implanted in collaboration with the ISOLDE facility located at CERN. We present results from a complete characterization of the sources. Each sample provides a radon emanation rate of about 2 Bq, which has been measured using electrostatic radon monitors as well as miniaturized proportional counters. Additional measurements using HPGe and alpha spectrometry as well as measurements of the radon emanation rate at low temperatures were carried out. • Production of 222Rn emanating stainless steel sources by implantation of 226Ra. • Measurement of the implanted activity (8 Bq) with HPGe- and alpha-spectrometry. • Radon emanation rate (2 Bq) measured by radon monitor and proportional counter. • Recoil dominated emanation without significant dependence on temperature and pressure. [ABSTRACT FROM AUTHOR]

The results of monitoring radon emanations in the territory of Gorno-Altaisk due to seismic activity and their influence on human health are considered. It is shown that the level of activity of subsoil radon in the vicinity of the fault zone in the territory of Gorno-Altaisk exceeds such a level recorded in Moscow by 3-4 times. There is ambiguity in the behavior of radon as a precursor of a seismic event. Some radon anomalies are synchronous with moments of earthquakes and others correspond to quiet periods. The radon activity is more closely associated with the earthquakes localized in the aftershock zone of the Chuya earthquake. This is assumed to be caused by the network of fluid-conducting channels within the active fault between this region and the observation station. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the effects of radon emissions from uranium ore processing by David Comey in the September 1975 issue.

Burning natural gas in power plants may emit radon (222Rn) into the atmosphere. On the University Park campus of The Pennsylvania State University, atmospheric radon enhancements were measured and modeled in the vicinity of their two power plants. The three-part study first involved measuring ambient outdoor radon concentrations from August 2014 through January 2015 at four sites upwind and downwind of the power plants at distances ranging from 80 m to 310 m. For each plant, one site served as a background site, while three other sites measured radon concentration enhancements downwind. Second, the radon content of natural gas flowing into the power plant was measured, and third, a plume dispersion model was used to predict the radon concentrations downwind of the power plants. These predictions are compared to the measured downwind enhancements in radon to determine whether the observed radon concentration enhancements could be attributed to the power plants’ emissions. Atmospheric radon concentrations were consistently low as compared to the EPA action level of 148 Bq m−3, averaging 34.5 ± 2.7 Bq m−3around the East Campus Steam Plant (ECSP) and 31.6 ± 2.7 Bq m−3around the West Campus Steam Plant (WCSP). Significant concentrations of radon, ranging from 516 to 1,240 Bq m−3, were detected in the natural gas. The measured enhancements downwind of the ECSP averaged 6.2 Bq m−3compared to modeled enhancements of 0.08 Bq m−3. Measured enhancements around the WCSP averaged −0.2 Bq m−3compared to the modeled enhancements of 0.05 Bq m−3, which were not significant compared to observational error. The comparison of the measured to modeled downwind radon enhancements shows no correlation over time. The measurements of radon levels in the vicinity of the power plants appear to be unaffected by the emissions from the power plants. Implications: Radon measurements at sites surrounding power plants that utilize natural gas did not indicate that the radon concentrations originated from the plants’ emissions. There were elevated radon concentrations in the natural gas supply flowing into the power plants, but combustion dilution puts the concentration below EPA action levels coming out of the stack, so no hazardous levels were expected downwind. Power plant combustion of natural gas is not likely to pose a radiation health hazard unless very different gas radon concentrations or combustion dilution ratios are encountered. [ABSTRACT FROM AUTHOR]

The health risk from thoron (Rn-220) is usually ignored owing to its short half-life (55.6 s), but the generated thoron decay products can cause a significant dose contribution. In this study, altogether 51 Slovenian soil samples were investigated using an accumulation chamber technique to obtain information about thoron exhalation features. The obtained (massic) thoron exhalation results varied between 6.9 and 149 mBq·kg−1·s−1 (average: 55.2 mBq·kg−1·s−1). The Th-232 content was determined using HPGe gamma spectrometry. The Th-232 activity concentration ranged between 9.3 and 161.7 Bq·kg−1 (average: 64.6 Bq·kg−1). The thoron emanation features were also calculated from the obtained results (2.9 to 21.2% with an average of 8.6%). The thoron exhalation and emanation properties were compared with the radon exhalation and emanation features determined in a previous study. It was found that there was no correlation between the radon and thoron emanation features, according to the obtained data. This can be explained by the different Ra-224 and Ra-226 distributions in the soil grains. As a result, the thoron emanation factor cannot be predicted from radon emanation and vice versa. [ABSTRACT FROM AUTHOR]

Previous experimental studies showed that the variation of Radon (Rn) emission is closely related to the development of rock deformation: Rn emission has a rapid increase with the growth of cracks and their surface areas (i.e. onset of fracture coalescence point), and reaches the maximum at rock failure. In this study, the stress level at the onset of fracture coalescence λ is predicted with the renormalization group theory. It is assumed that rock is a strain-softening medium whose strength can be described by Weibull's distribution. Result shows that λ depends mainly on the homogeneity index or shape parameter m in the Weibull's distribution for the rock. Both experimental and analytical results show that this point of rapid increase in Rn emission on the Rn-strain curve corresponds to the critical point on the stress-strain curve; for rock compression, the stress at this point is approximately 70-80 % of the peak strength. Hence a generalized crack damage threshold is proposed in the present study based on the characteristics of Rn emission during the loading process, for recognizing the critical point of rock fracture. [ABSTRACT FROM AUTHOR]

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Voltage source converter (VSC)-based high voltage direct current (VSC-HVDC) interconnectors can realize accurate and fast control of power transmission among AC networks, and provide emergency power support for AC networks. VSC-HVDC interconnectors bring exclusive fault characteristics to AC networks, thus influencing the performance of traditional protections. Since fault characteristics are related to the control schemes of interconnectors, a fault ride-through (FRT) strategy which is applicable to the interconnector operating characteristic of working in four quadrants and capable of eliminating negative-sequence currents under unbalanced fault conditions is proposed first. Then, the additional terms of measured impedances of distance relays caused by fault resistances are derived using a symmetrical component method. Theoretical analysis shows the output currents of interconnectors are controllable after faults, which may cause malfunctions in distance protections installed on lines emanating from interconnectors under the effect of fault resistances. Pilot protection is also inapplicable to lines emanating from interconnectors. Furthermore, a novel pilot protection principle based on the ratio between phase currents and the ratio between negative-sequence currents flowing through both sides is proposed for lines emanating from the interconnectors whose control scheme aims at eliminating negative-sequence currents. The validity of theoretical analysis and the protection principle is verified by PSCAD/EMTDC simulations. [ABSTRACT FROM AUTHOR]