Publications
Development of a new tool to simultaneously measure soil-gas permeability and CO2 concentration as important parameters for geogenic radon potential assessment
Authors: Miroslaw Janik, Christopher Gomez, Satoshi Kodaira, Dominik Grzadziel
Journal: Environmental Monitoring and Assessment
Volume: 197
Issue: 2
Pages: 124
Year: 2025
Abstract: This study assessed the geogenic radon potential using PECAME, an innovative tool designed to simultaneously measure soil-gas permeability and CO2 concentration — two key parameters for understanding radon transport in soil. Comparative field studies using the RADON-JOK device in various geological settings in Japan and Poland demonstrate the effectiveness of PECAME. These studies reveal a strong correlation between PECAME and RADON-JOK, with an R value of 0.94 for flow rate of 3.5 dm3 min-1. Since the soil-gas Rn concentration and permeability were measured simultaneously, the geogenic radon potential was calculated. Most measured points fall within the low to medium radon index zones, with two exceptions near active faults located in the high zone. Therefore, permeability and CO2 measurements using PECAME may facilitate further research in Japan to develop a comprehensive geogenic radon potential map.
Development of a new tool to simultaneously measure soil-gas permeability and CO$$_2$$ concentration as important parameters for geogenic radon potential assessment
Authors: Miroslaw Janik, Christopher Gomez, Satoshi Kodaira, Dominik Grzadziel
Journal: Environmental Monitoring and Assessment
Volume: 197
Issue: 2
Pages:
Year: 2025
Abstract: This study assessed the geogenic radon potential using PECAME, an innovative tool designed to simultaneously measure soil-gas permeability and CO concentration — two key parameters for understanding radon transport in soil. Comparative field studies using the RADON-JOK device in various geological settings in Japan and Poland demonstrate the effectiveness of PECAME. These studies reveal a strong correlation between PECAME and RADON-JOK, with an R value of 0.94 for flow rate of 3.5 dm min. Since the soil-gas Rn concentration and permeability were measured simultaneously, the geogenic radon potential was calculated. Most measured points fall within the low to medium radon index zones, with two exceptions near active faults located in the high zone. Therefore, permeability and CO measurements using PECAME may facilitate further research in Japan to develop a comprehensive geogenic radon potential map.
Radon-thoron exhalation and emanation determinations from mylonitic rock samples collected in north Abu Rusheid, Egypt
Authors: Sara Sakr, Sarata Kumar Sahoo, Kazumasa Inoue, Gehad Mohamed Saleh, Mohamed Salem Kamar, Mohamed Galal El Feky, Atef El-Taher, Miroslaw Janik
Journal: Environmental Monitoring and Assessment
Volume: 197
Issue: 5
Pages:
Year: 2025
Abstract: Mylonitic rocks in north Abu Rusheid, Egypt, contain naturally occurring radioactive materials (NORMs), making them potential sources of indoor radon (Rn) and thoron (Tn) exposure when used as building materials. Furthermore, they pose occupational exposure risks for miners. Rn mass exhalation rate (RnEX), Tn mass exhalation rate (TnEX), Rn emanation fraction (RnEM), and Tn emanation fraction (TnEM) were evaluated simultaneously in 27 mylonitic rock samples collected from three trenches (TCHA, TCHB, and TCHC) in the area. The powder sandwich technique has been carried out using a RAD7 detector to assess RnEX and TnEX. Additionally, gamma spectroscopy was used to evaluate RnEM and TnEM parameters. The RnEX and TnEX values varied from 0.10 to 1.13 and 83 to 5757 Bq kg−1 h−1, respectively, while the RnEM and TnEM values ranged from 0.055 to 0.182 and 0.017 to 0.078, respectively. The activity concentrations of 226Ra and 232Th varied from 127 to 1524 and 96 to 2420 Bq kg−1, respectively, and the mean values exceeded the worldwide average values of 33 and 45 Bq kg−1, respectively. Positive correlations between 226Ra and RnEX, and 232Th and TnEX were observed among the trenches. However, no systematic relations were identified between 226Ra and RnEM, 232Th and TnEM, or 226Ra and 232Th, which could be attributed to geological factors. The findings of this study highlighted the potential radiation hazards associated with mylonitic rock use in construction and mining, emphasizing the need for radioprotection measures.
Evaluating Soil Temperature Variations for Enhanced Radon Monitoring in Volcanic Regions
Authors: Miroslaw Janik, Mashiro Hosoda, Shinji Tokonami, Yasutaka Omori, Naofumi Akata
Journal: Atmosphere
Volume: 16
Issue: 4
Pages: 460
Year: 2025
Abstract: Soil temperature, a key factor in subsurface geochemical processes, is influenced by environmental and geological dynamics. This study analyzed hourly soil temperature variations at depths of 10 to 100 cm near the Sakurajima volcano, alongside concurrent ambient temperature measurements. By applying temperature models and statistical methods, we characterized both seasonal and short-term thermal dynamics, including soil-atmosphere thermal coupling. Our findings revealed a depth-dependent thermal diffusivity, establishing distinct thermal regimes within the soil profile. The soil’s strong thermal buffering capacity, evidenced by increasing amplitude attenuation and temporal lag with depth, allowed us to identify optimal instrument placement depths (80–100 cm) for minimal diurnal temperature influence. We also quantified the relationship between ambient temperature fluctuations and soil thermal response at various depths, as well as the impact of these temperature variations on soil permeability. These results enhance our understanding of subsurface thermal behaviour in volcanic environments and offer practical guidance for environmental monitoring and geohazard studies.
Analysis of Outdoor and Indoor Radon Concentration Time Series Recorded with RadonEye Monitors
Authors: Peter Bossew, Eleonora Benà, Scott Chambers, Miroslaw Janik
Journal: Atmosphere
Volume: 15
Issue: 12
Pages: 1468
Year: 2024
Abstract: Consumer-grade economical radon monitors are becoming increasingly popular in private and institutional use, in the contexts of both Citizen Science and traditional research. Although originally designed for screening indoor radon levels in view of radon regulation and decisions about mitigation or remediation—motivated by the health hazard posed by high radon concentrations—researchers are increasingly exploring their potential in some environmental studies. For long time, radon has been used as a tracer for investigating atmospheric transport processes. This paper focuses on RadonEye, currently the most sensitive among low-cost monitors available on the market, and specifically, its potential use for monitoring very low radon concentrations. It has two objectives: firstly, discussing issues of statistics of low count rates, and secondly, analyzing radon concentration time series acquired with RadonEyes outdoors and in low-radon indoor spaces. Regarding the first objective, among other things, the inference radon concentration reported to expected true is discussed. The second objective includes the application of autoregressive methods and fractal statistics to time series analysis. The overall result is that radon dynamics can be well captured using this “low-tech” approach. Statistical results are plausible; however, few results are available in the literature for comparison, particularly concerning fractal methods. The paper may therefore be seen as an incentive for further research in this direction.
Spectroscopic analysis of alpha particles from radioactive nuclides with CR-39 plastic nuclear track detectors
Authors: Satoshi Kodaira, Miroslaw Janik
Journal: Radiation Protection Dosimetry
Volume: 200
Issue: 16-
Pages: 1686-1691
Year: 2024
Abstract: A spectroscopy method of alpha particles with the track geometry parameters in CR-39 plastic nuclear track detectors is proposed. The relationship between the track registration sensitivity and incident angle of each etch pit is analyzed. The components of alpha particles emitted from radon, thoron and 241Am can be roughly separated when the etching level is not exceeded beyond the range in CR-39. This work aims at improving the dose assessment accuracy from exposure to indoor radon and thoron.
DOI: 10.1093/rpd/ncae068
Evaluation of an ionization chamber characteristics for 222Rn calibration
Authors: Rio Furukawa, Miroslaw Janik, Satoshi Kodaira, Hiroki Hashimoto, Yasutaka Omori, Shinji Tokonami, Masahiro Hosoda, Morihito Shimizu, Seiya Manabe, Tetsuro Matsumoto, Chihiro Shimodan, Y
Journal: Radiation Protection Dosimetry
Volume: 200
Issue: 16-
Pages: 1696-1700
Year: 2024
Abstract: The National Metrology Institute of Japan plan to use an inner-through-type ionization chamber (IC) as a working standard to calibrate radon monitors. Novel methods to calibrate the IC were described, and the calibration factor, CF [Bq m −3 A−1], of the IC with its expanded uncertainty (k = 2) was evaluated to be (2.0 ± 0.2) × 1016 Bq m−3 A−1 in the order of 10−13 A in the IC output current. In this study, the CFs, evaluated under sampling conditions between continuous gas flowing and stationary gas filled inside the IC, were in agreement within the uncertainty.
DOI: 10.1093/rpd/ncae028
Preliminary results of spatial distribution of radon and thoron with associated parameters in soil around active faults in Japan
Authors: Miroslaw Janik, Christopher Gomez, Satoshi Kodaira, Md Mahamudul Hasan
Journal: Radiation Protection Dosimetry
Volume: 200
Issue: 16-
Pages: 1726-1731
Year: 2024
Abstract: The radon (Rn) and thoron (Tn) concentrations and other environmental parameters were measured in the vicinity of active faults in two regions with different geology structure of Japan. The range of measured values was from 1.2 to 74 kBq m$^{-3}$, 1.1 to 38.9 kBq m$^{-3}$, 0% to 4.35%, and 2$\times $10$^{-13}$ to 4$\times $10$^{-11}$ m$^{2}$, for Rn, Tn, CO$_{2}$, and soil permeability, respectively. Significant differences in the measured parameters were observed, suggesting that Rn concentrations near faults are strongly influenced by geological structure and fault type. Based on statistical analysis, good correlations were found between Rn, Tn, and CO$_{2}$ (carried gas ) concentrations. It is planned to continue the study with measurements at a number of additional sites.
DOI: 10.1093/rpd/ncae117
Alpha particle spectrometry in fluorescent nuclear track detectors with an automatic 3D track reanalysis algorithm
Authors: Jun Hu, Tamon Kusumoto, Miroslaw Janik, Satoshi Kodaira
Journal: Radiation Measurements
Volume: 170
Issue:
Pages: 107051
Year: 2024
Abstract: The main obstacle to applying aluminum oxide doped with carbon and magnesium (Al2O3:C,Mg)-based fluorescent nuclear track detectors (FNTDs) in radionuclide therapy with alpha emitters is that it has not been known how to achieve an accurate and in situ dose assessment for in vitro cellular experiments. In this study, we developed an automatic 3D track reanalysis algorithm (ATRA) to analyze the alpha energy spectra in FNTDs. The algorithm provides an excellent track identification rate and an excellent track linking rate (0.961) without significant variations in various track densities. The algorithm also achieves a reliable track detection rate exceeding 0.927 for track densities at the level of in situ measurement, and it successfully measures the alpha energy spectra for obtaining the absorbed dose. We also confirmed that the track overlap clearly interferes with accurate track reconstruction for track densities beyond 1.5 × 106 tracks cm−2. We provided a correction equation that can be used to obtain the actual alpha tracks for high track densities; the equation may also correct estimations of absorbed doses due to alpha particles.
Machine learning in environmental radon science
Authors: Javier Elío, Eric Petermann, Peter Bossew, Miroslaw Janik
Journal: Applied Radiation and Isotopes
Volume: 194
Issue:
Pages: 110684
Year: 2023
Abstract: Temporal dynamic as well as spatial variability of environmental radon are controlled by factors such as meteorology, lithology, soil properties, hydrogeology, tectonics, and seismicity. In addition, indoor radon concentration is subject to anthropogenic factors, such as physical characteristics of a building and usage pattern. New tools for spatial and time series analysis and prediction belong to what is commonly called machine learning (ML). The ML algorithms presented here build models based on sample and predictor data to extract information and to make predictions. We give a short overview on ML methods and discuss their respective merits, their application, and ways of validating results. We show examples of 1) geogenic radon mapping in Germany involving a number of predictors, and of 2) time series analysis of a long-term experiment being carried out in Chiba, Japan, involving indoor radon concentrations and meteorological predictors. Finally, we identified the main weakness of the techniques, and we suggest actions to overcome their limitations.
Indoor Radon Research in the Asia-Pacific Region
Authors: Miroslaw Janik, Peter Bossew, Md Mahamudul Hasan, Giorgia Cinelli
Journal: Atmosphere
Volume: 14
Issue: 6
Pages: 948
Year: 2023
Abstract: Indoor radon is a major hazard to human health; it is one of the leading causes of lung cancer. Therefore, radon research in Asia has intensified recently due to the growing awareness of the harm that radon poses. An analysis of the collected literature data showed that in Asia–Oceania, some regions have—or are believed to have—little indoor radon problems due to climate and low Rn ground. It can be concluded that countries have their own approaches, techniques, and protocols. Data were not harmonized within each region; however, measurement techniques were compared by regional intercomparison exercises. The situation differs regarding studies on the usability of radon as a tracer or potential predictor of tectonic phenomena, as some countries are in seismically active zones, such as India, Taiwan, China, Japan, etc. India and Taiwan are global leaders in this research, as well as Italy, which is another seismically affected country. We provide an overview of radon-related surveying and research activities conducted in the western, southern, and eastern Asian regions over the past few years. Additionally, we observed that the number of indoor radon measurements per million inhabitants increases as the human development index (HDI) increases.
Preliminary population exposure to indoor radon and thoron in Dhaka city, Bangladesh
Authors: Md Mahamudul Hasan, Miroslaw Janik, Shikha Pervin, Takeshi Iimoto
Journal: Atmosphere
Volume: 14
Issue: 7
Pages: 1067
Year: 2023
Abstract: Radon, an element of natural radiation, is considered one of the leading causes of lung cancer worldwide. In Bangladesh, radon has been clarified as a foremost source of radiation exposure. Potential natural-radiation-induced elevated cancer risks were estimated in Bangladesh previously for the population. In this survey, as a very preliminary study in the country, comparative indoor radon (222Rn, Rn) and thoron (220Rn, Tn) concentration/population exposure was determined for the multistoried dwellings of south-western areas of Dhaka city. RADUET was used to assess annual Rn and Tn concentrations in determining the primary inhalation dose for the population. The annual effective dose of Rn and Tn was evaluated in this study for dwellings at 0.3 mSvy−1, constituting a Tn dose contribution of an average of 40% with a dwelling-based wide range of 10–96%. Thus, Tn should not be neglected for Bangladesh while estimating radiological inhalation dose from the indoor environment. Again, the equilibrium factors, F of Rn and Tn, were determined by short-term measurement at averages of 0.6 and 0.02, respectively. Furthermore, using questionnaire estimation by principal component analysis, PCA following the dwelling characteristics, human lifestyles, and estimated long-term indoor Rn and Tn concentrations, this paper discussed indoor atmospheric/Rn factors for the investigated multistoried dwellings in Dhaka city.
Baseline study on radiological and mineralogical investigations of heavy mineral depositions on the south–west coast of India
Authors: Trilochana Shetty, Ateeth Shetty, A. Anil Kumar, K. G. Mohan, M. P. Mohan, N. Karunakara, Mukesh Prasad, M. Janik, K. S. Jayappa and H. M. Somashekarappa
Journal: Journal of Radioanalytical and Nuclear Chemistry
Volume:
Issue:
Pages:
Year: 2023
Abstract: Pristine depositions of beach sediments containing heavy minerals (HM) along the shorelines of Mangalore, south–west coast of India is reported in the study. Primordial radionuclide concentrations in the beach sediments collected were determined by high purity germanium (HPGe) gamma spectrometry method. The mineral identification and counting were performed using polarizing microscope. Geometric mean values (GM) [Geometric Standard Deviation (GSD)] of concentrations of 40K, 232Th and 226Ra are obtained to be 139 (2), 482 (5) and 110 (4) Bq kg−1 respectively and total heavy mineral weight percentage (TM%) of Monazite, Zircon, Ilmenite and Lithic fragments are obtained to be 0.17 (3.5), 0.51 (2.9), 5.3 (3.2) and 2.3 (2.5)% respectively. Seasonal variation studies and statistical analysis of the data are also performed to examine correlations between the origins of the radionuclides and elevated percentage of HM in these sediment depositions.
Standardization of Rn-222 concentration using the multi-electrode proportional counter
Authors: Rio Furukawa, Miroslaw Janik, Satoshi Kodaira, Seiya Manabe, Tetsuro Matsumoto, Chihiro Shimodan, Yasushi Sato, Hideki Harano
Journal: Applied Radiation and Isotopes
Volume: 202
Issue:
Pages: 110076
Year: 2023
Abstract: Standardization of the concentration of gaseous 222Rn based on a multi-electrode proportional counter (MEPC) is under development as a primary standard in Japan. In this study, the concept and evaluation of its performance are reported. The latter consists of a preliminary result for the uncertainty budget associated with the measurement of the MEPC and compensation of the electric field distortion in the MEPC. Moreover, an ionization-chamber-based gas circulation system was added for the calibration of radon monitors in the air.
A CONTRIBUTION TO THE CURRENT DEBATE ABOUT THE ADEQUACY OF THE LINEAR-NO-THRESHOLD (LNT) MODEL FOR THE RISK RESULTING FROM RADON EXPOSURE.
Authors: J. Elio, M. Janik, P. Bossew
Journal: RAP Coreference Proceedings
Volume: 8
Issue:
Pages: 65–74
Year: 2023
Abstract: The Linear-No Threshold Hypothesis (LNT) states that risk from ionizing radiation is linearly related to dose with no dose threshold below which there was no risk. The LNT is an important fundament in practical radioprotection and for assessment of population risk, e.g., of estimating lung cancer risk or incidence attributable to exposure to indoor radon. The popularity of the LNT stems largely from its mathematical simplicity and therefore, its practicability. It seems that this has obscured the question of whether it is physically true, or “only” a useful practical rule. Distribution of exposure and dose to radon through the population is strongly right-skew, with the bulk of dose low. Therefore, attribution of risk, i.e., mainly lung cancer incidence, depends strongly on the risk model for low dose. As long as no micro-dosimetric model exists which causally relates incident radiation flux or exposure to radon progeny to a sequence of effects, starting on sub-cellular level, which results in clinical evidence, it is impossible to make statements on the effect of very low doses, since it is in principle impossible to extend empirical epidemiological inference to arbitrarily small doses. Therefore, epidemiological findings are extrapolated towards low doses. The most quoted large-scale epidemiological radon meta-study is Darby et al. (2006), which concludes that the LNT model is statistically compatible with the findings. This has been essentially corroborated by newer studies. However, with availability or more data, there seems to be increasing evidence that the model may not be applicable to estimate risk for low doses, which represent the bulk of exposure, if the objective is assessment of population risk. We review literature about the strongly debated question about validity of the LNT. Data are not publicly available, therefore statistical re-analysis is impossible. However, published information in the form of graphs and statistics allows some hypotheses alternative to the LNT. The debate is so serious because of the political consequences regarding radon abatement policy. We refrain from stating any “alternative truth” but investigate the possible consequences for risk assessment and what they entail for radon regulation and policy, resulting from different risk models.
Environmental Radioactivity Monitoring and Measurements: Radon and Thoron
Authors: Miroslaw Janik
Journal: International Journal of Environmental Research and Public Health
Volume: 19
Issue: 15
Pages: 9276
Year: 2022
Abstract: We “bathe” in radiation, which is an integral part of our environment. All living beings are exposed to a flux of natural radiation, which is the primary source of human non-medical exposure to ionizing radiation. The most variable component of the population dose is exposure to naturally occurring radon and thoron gas as well as their progenies, which account for more than 50% of the total effective dose received from all sources of natural radiation (2.4 mSv annual dose) [1]. Recent epidemiological studies suggest that exposure to radon leads to an increased risk of lung cancer. An integrated strategy or action plan for national radon control is needed to reduce human exposure to radon.
Radon Exposure in the Underground Tourist Route–Historic Silver Mine in Tarnowskie Góry, Poland
Authors: Agata Grygier, Krystian Skubacz, Malgorzata Wysocka, Michal Bonczyk, Adam Piech, Miroslaw Janik
Journal: International Journal of Environmental Research and Public Health
Volume: 19
Issue: 23
Pages: 15778
Year: 2022
Abstract: An assessment of the exposure of workers and tourists to radon in the underground tourist route of the Historic Silver Mine in Tarnowskie Góry was carried out. The study was conducted over a one-year period to capture seasonal variations in radon concentrations. CR-39 track detectors were used to measure radon concentrations, which were exposed in the mine during the following periods: 9 February 2021–19 May 2021, 19 May 2021–26 August 2021, 26 August 2021–25 November 2021 and 25 November 2021–3 March 2022. The annual average radon concentration along the tourist route was 1021 Bq m−3 . The highest measured concentration was 2280 Bq m−3 and the lowest concentration was 80 Bq m−3. Based on the measured concentrations, effective doses were calculated, assuming that employees spend 1350 h a year in underground areas and that the time of visiting the mine by tourists is ca. 1 h. The average annual effective dose a worker would receive is approximately 2.5 mSv, and a tourist below 2 μ Sv. The dose limit expressed as the annual effective dose is 1 mSv for members of the general public and 20 mSv for occupational exposure.
Utilization of Computational Fluid Dynamics Simulation for Gas Exposure Chamber
Authors: Kazuki Iwaoka, Miroslaw Janik, Yuki Tamakuma, Masahiro Hosoda, Shinji Tokonami, Reiko Kanda
Journal: Radiation Environment and Medicine
Volume: 11
Issue: 2
Pages: 61-65
Year: 2022
Abstract: Testing devices and measuring physical parameters are often carried out in gas chambers. However, if the environmental conditions (e.g. gas concentration) inside the chamber is inhomogeneous, we may expect incorrect results of experiment. Confirmation of the gas distribution in various environmental conditions is an important problem in the design of the chamber. For checking the gas distribution, a theoretical approach using the computational fluid dynamics (CFD) simulation can be relatively-easily used. The article demonstrates the utilization of numerical calculations based on the CFD simulation for the analysis of gas uniformity in the virtual chamber.
Thoron Equilibrium Factor Observed around Chhatrapur Placer Deposit, a High Background Radiation Area in Odisha, India
Authors: Yasutaka Omori, Ganesh Prasad, Devulapalli Vidya Sagar, Sarata Kumar Sahoo, Atsuyuki Sorimachi, Miroslaw Janik, Tetsuo Ishikawa, Rakesh Ch Ramola, Shinji Tokonami
Journal: Radiation Environment and Medicine
Volume: 11
Issue: 2
Pages: 50-55
Year: 2022
Abstract: In thoron (220Rn)-prone areas, the contribution from thoron (including progenies) can be equal to or exceed that from radon (222Rn) during radiation exposure. The dose estimation is practically performed using the thoron concentration and thoron equilibrium factor. In the present study, thoron equilibrium factors were determined from direct measurements of thoron and its progeny concentrations for dwellings in the high background radiation area of Odisha, India. The results show that the equilibrium factor has a seasonal variation, with a minimum in winter and a maximum in summer. The frequency distributions exhibit log normality with geometric means of 0.025, 0.044, and 0.051 in winter, rainy, and summer-seasons, respectively. The annual average of 0.04 is observed to be in the order of the United Nations Scientific Committee on the Effects of Atomic Radiation recommended value (i.e., 0.02).
Status of radon exposure in Bangladeshi locations and dwellings
Authors: Md Mahamudul Hasan, Miroslaw Janik, Akihiro Sakoda, Takeshi Iimoto
Journal: Environmental Monitoring and Assessment
Volume: 193
Issue:
Pages: 1-10
Year: 2021
Abstract: Potentially higher cancer risk due to exposure from natural background radiation was indicated for the Bangladeshi population by estimations based on the countrywide study. Several regions with elevated natural background exhibited higher soil radium and thorium contents than the world average. Being the decay products of these radioactive elements, natural radon isotopes could constitute environmental risk factors for internal radiation exposure to the lungs of people living in these areas. Although lung cancer is one of the most prevalent types of cancer in Bangladesh, its status and features are still unclear. To clarify the present status of one of the potential risk factors for lung cancer in the country, this review intends to ascertain the countrywide radon exposure, and its pathways by types of local dwelling and by regions, which would provide an indication of the internal exposures in areas of elevated natural background radiation and radionuclides of soil as well as an understanding of the preliminary contribution of environmental radon on the country’s lung cancer prevalence. In this review, countrywide monitored air radon exposures for Bangladeshi dwellings and workplaces are organized from peer-reviewed published papers. Radon has been identified as one of influential sources of radiation dose in Bangladesh with its higher radon exhalation and emanation rate from soil. A novel nationwide depiction of the overall assessed indoor and soil radon levels for Bangladesh has been made through radiation maps. This would be helpful for designing future systematic radon/radiological monitoring and research on the country’s lung cancer prevalence.
Effects of storage time and pre-etching treatment of CR-39 detectors on their response to alpha radiation exposure
Authors: Miroslaw Janik, Md Mahamudul Hasan, Peter Bossew, Norbert Kavasi
Journal: International Journal of Environmental Research and Public Health
Volume: 18
Issue: 16
Pages: 8346
Year: 2021
Abstract: Radon passive monitors based on solid state nuclear track detectors (SSNTD), especially CR-39, are widely used in radon and thoron studies. They may be subjected to the influence of external factors, like changing of temperature, humidity, and pressure, both before and during the measurement. Evaluation of the exposed detectors involves chemical processing, whose conditions also influence the measurement results. The aim of this study was to check several factors, as to whether they may modify the response of CR-39 detector: concerning the phase before evaluation, storage time, and temperature during storage; and concerning the evaluation procedure, etching time, and pre-etching treatment using hot water and carbon dioxide atmosphere. Two experiments were conducted by irradiation of CR-39 detectors using alpha particles emitted from a mono-energetic 241Am source and exposed in radon atmosphere. Track density dependence of the age of production was found to be statistically not significant. On the other hand, pre-etching treatment using hot water and carbon dioxide with different etching times showed statistically significant effects on track area, track sensitivity, and roundness. It was concluded that there are simple methods to increase performance of nuclear track detectors, and that storage time is not a factor of concern.
Variable strength in thoron interference for a diffusion-type radon monitor depending on ventilation of the outer air
Authors: Yasutaka Omori, Michikuni Shimo, Miroslaw Janik, Tetsuo Ishikawa, Hidenori Yonehara
Journal: International Journal of Environmental Research and Public Health
Volume: 17
Issue: 3
Pages: 974
Year: 2020
Abstract: Thoron interference in radon measurements using passive diffusion radon detectors/monitors is a crucial problem when it comes to assessing the internal exposure to radon precisely. The present study reported, as one of the potential factors, the effects of air flow conditions on changes in thoron interference. Rates of thoron infiltration (as thoron interference) into the diffusion chamber of the monitor were evaluated. The temporal variation was obtained based on measurements of the underfloor space of a Japanese wooden dwelling using a diffusion-type radon monitor, a reference radon monitor which was not affected by thoron interference, and a thoron monitor. The thoron infiltration rate for the diffusion-type monitor varied from 0% to 20%. In particular, it appeared to increase when ventilation of the underfloor space air was forced. The variable thoron infiltration rate, with respect to ventilation strength, implied that not only a diffusive process, but also an advective process, played a major role in air exchange between the diffusion chamber of the monitor and the outer air. When an exposure room is characterized by the frequent variation in air ventilation, a variable thoron response is considered to occur in radon-thoron discriminative detectors, in which only diffusive entry is employed as a mechanism for the discrimination of radon and thoron.
Passive-type radon monitor constructed using a small container for personal dosimetry
Authors: Yuki Tamakuma, Chutima Kranrod, Takahito Suzuki, Yuki Watanabe, Thamaborn Ploykrathok, Ryoju Negami, Eka Djatnika Nugraha, Kazuki Iwaoka, Mirosław Janik, Masahiro Hosoda
Journal: International Journal of Environmental Research and Public Health
Volume: 17
Issue: 16
Pages: 5660
Year: 2020
Abstract: The International Commission on Radiological Protection (ICRP) recently recommended a new dose conversion factor for radon based on the latest epidemiological studies and dosimetric model. It is important to evaluate an inhalation dose from radon and its progeny. In the present study, a passive radon personal monitor was designed using a small container for storing contact lenses and its performance was evaluated. The conversion factor for radon (222Rn), the effect of thoron (220Rn) concentration and the air exchange rate were evaluated using the calibration chamber at Hirosaki University. The minimum and maximum detectable radon concentrations were calculated. The conversion factor was evaluated as 2.0 ± 0.3 tracks cm−2 per kBq h m−3; statistical analyses of results showed no significant effect from thoron concentration. The minimum and maximum detectable radon concentrations were 92 Bq m−3 and 231 kBq m−3 for a measurement period of three months, respectively. The air exchange rate was estimated to be 0.26 ± 0.16 h−1, whose effect on the measured time-integrated radon concentration was small. These results indicate that the monitor could be used as a wearable monitor for radon measurements, especially in places where radon concentrations may be relatively high, such as mines and caves.
Machine learning as a tool for analysing the impact of environmental parameters on the radon exhalation rate from soil
Authors: Masahiro Hosoda, Shinji Tokonami, Takahito Suzuki, Miroslaw Janik
Journal: Radiation Measurements
Volume: 138
Issue:
Pages: 106402
Year: 2020
Abstract: Interest in radon (Rn) is not limited only to its impact on health and its dose to the public, but due to its properties, the techniques to analyse its behavior can be used in many fields such as radiotherapy, atmospheric physics, geophysics, geohazards, mineral exploration, and even planetary science. Nowadays machine learning methods provide extremely important tools for intelligent environmental data analysis, processing and visualization. We describe application of machine learning to environmental sciences with an emphasis on the radon exhalation rate in order to express responses from multivariable time-series data collected at a measuring site near the Sakurajima volcano (Kagoshima, Japan).
Comparison of radon and thoron concentration measuring systems among Asian countries
Authors: Miroslaw Janik, Shinji Tokonami, Kazuki Iwaoka, Naregundi Karunakara, Shetty Trilochana, Mandya Purushotham Mohan, Sudeep Kumara, Indaje Yashodhara, Weihai Zhuo, Chao Zhao, Fangd
Journal: International Journal of Environmental Research and Public Health
Volume: 16
Issue: 24
Pages: 5019
Year: 2019
Abstract: Comparison is an important role in the quality control and quality assurance for any measuring system. Due to the future legal regulations regarding radon levels in the air, maintaining the system quality and harmonization of results as well as validation of radon and thoron measuring systems is important. The aim of this work is to validate the degrees of equivalence and measurement precisions of the existing five radon and four thoron measuring systems located in four Asian countries (China, India, Japan and Thailand) through comparison experiment. In this project, comparison experiment was performed in order to derive the ratio between assigned value obtained from one transfer measurement device for radon and one transfer measurement device for thoron belongs to National Institutes for Quantum and Radiological Science and Technology and participants’ value from their measuring instrument. As a result, the ratio value associated with measurement uncertainty was derived for each activity concentration. Finally, measurement bias and degrees of equivalence between the assigned values and values of measurement quantity from participants’ measuring instruments were statistically analysed and presented.
Preliminary technical discussion on a new radon and its progeny continuous monitor using two-filter method
Authors: Yu Igarashi, Takahiro Nozaki, Hiroyuki Mizuno, Tomohiro Kuroki, Yuki Uchida, Miroslaw Janik, Takeshi Iimoto
Journal: Radiation Protection Dosimetry
Volume: 184
Issue: 3-4
Pages: 418-421
Year: 2019
Abstract: Focusing on the scalability of Two-Filter Method, we started to develop a monitor for the concentration of radon and its progeny. In this study, we investigated the influence of a high-humidity environment on measuring radon concentration, and the influence of the decay chamber of the monitor on the measurement. In the high-humidity test, the conversion factor of (Bqm−3)/(cpm) tends to raise with increasing humidity. On the measurement of radon progeny, existence of the decay chamber of the monitor makes measurement sensitivity lower under environments of little aerosols. Radon concentration measurement by the developed monitor could be influenced by environmental humidity, and that counting loss could occur due to deposition of radon progeny inside of the decay chamber. Correction relating these would be needed based on the data of calibration tests.
Evaluation of a radon air monitor in the measurement of radon concentration in water in comparison with a liquid scintillation counter
Authors: Shoko Higuchi, Yuuki Kamishiro, Maki Ishihara, Yumi Yasuoka, Yasunori Mori, Masahiro Hosoda, Kazuki Iwaoka, Shinji Tokonami, Rikiya Takahashi, Miroslaw Janik
Journal: Radiation Protection Dosimetry
Volume: 184
Issue: 3-4
Pages: 426-429
Year: 2019
Abstract: The World Health Organisation (WHO) recommends that the concentration of radon in water should be no more than 100 kBq m−3 (100 BqL−1) and the Codex Alimentarius Commission states that the limit of quantification (LOQ) of a method should be no more than one-fifth of this value. In this study, a degassing method with an RAD7 device was used to measure radon concentrations in water, compared to a liquid scintillation counter (LSC) method used as the reference, to investigate whether the numerical value of the LOQ of this method was more than 1/5 (20 kBq m–3) of 100 kBq m–3. The degassing method with leak prevention was shown to reach a target value of 20 kBq m−3 or less under a relative humidity of 6% or lower in the chamber of the RAD7 device. Accordingly, the RAD7 degassing method with leak prevention can be used to accurately measure radon concentrations in water within the guidance level set out by the WHO.
Characteristics of indoor radon and thoron concentrations in cave dwellings in Gansu Province, China
Authors: A. Sorimachi, S. Tokonami, S, Y. Omori, M. Janik, K. Iwaoka, T. Ishikawa, Q. Sun
Journal: Radiation Protection Dosimetry
Volume: 184
Issue: 3-4
Pages: 457-462
Year: 2019
Abstract: Short-term measurements were made in four different types of Chinese cave dwellings, ‘ground’, ‘open-cut’, ‘aboveground’ and ‘underground’, located in Gansu Province, China, in order to evaluate the diurnal and seasonal variations in indoor radon (222Rn) and thoron (220Rn) concentrations. As a result, in most of the ‘ground’ and ‘open-cut’ cave dwellings in summer, the indoor 222Rn concentrations during the nighttime were higher than those during the daytime. In the winter, such fluctuation was not observed. The daily indoor 222Rn concentrations in summer were higher than those in winter, excluding the ‘aboveground’ cave dwelling, and these concentrations depended on dwelling type, exhalation from the building materials and ventilation. In contrast with 222Rn, there seemed to be only very slight clear variations in 220Rn.
A walk-in type calibration chamber facility for 222Rn measuring devices and inter-comparison exercises
Authors: S. Trilochana, HM Somashekarappa, KS Kumara, MP Mohan, SR Nayak, RS D’Souza, SS Kamath, BK Sahoo, JJ Gaware, BK Sapra, M Janik, D Al-Azmi, YS Mayya, N Karunakara
Journal: Radiation Protection Dosimetry
Volume: 187
Issue: 4
Pages: 466-481
Year: 2019
Abstract: A walk-in type 222Rn calibration chamber of volume 22.7 m3, which has traceability to international standards, is established at the Centre for Advanced Research in Environmental Radioactivity, Mangalore University, India. It has a human–machine interface communication system, a programmable logic controller and sensor feedback circuit for controlling and data acquisition of relative humidity (RH) and temperature (T). An innovative method for the generation of desired 222Rn concentration (a few hundred Bq m−3 up to about 36 kBq m−3) using soil gas as a source was adopted. Leak rates of 222Rn from the chamber for the mixing fan ON and OFF conditions were determined to be 0.0011 and 0.00018 h−1 respectively. With the exhaust system fully turned on, the maximum clearance rate of the chamber was 0.58 ± 0.07 h−1. Excellent spatial uniformity in 222Rn concentration in the chamber was confirmed (with a mean value of relative standard deviation < 12%) through measurements at 23 locations using CR-39 film-based passive devices. Demonstration of calibration applications was performed using charcoal canister and PicoRad vials as the 222Rn adsorption devices. The study shows that gamma spectrometry is a convenient alternative approach to liquid scintillation analysis of PicoRad vials for 222Rn measurement.
Derivation and Validity Evaluation of Calibration Factors for Activated-charcoal Radon Collectors
Authors: A. Wakabayashi, Y. Yasuoka, M. Janik, H. Nagahama, N. Fukuhori, Y. Mori, Y. Arai, S. Fujii, T. Mukai
Journal: RADIOISOTOPES
Volume: 68
Issue: 5
Pages: 317-329
Year: 2019
Abstract: Radon collectors (e.g., PicoRad collectors) based on activated-charcoal have been used for screening and measuring radon. However, researchers at the U. S. Environmental Protection Agency reported that they could not verify the proper functioning of some commercially available radon detectors, including PicoRad collectors. In this study, we exposed two lots (with different expiration dates) of PicoRad collectors to the reference conditions at a controlled radon concentration within a radon chamber because the calibration factors were derived for use by a semi-empirical equation. Further, we exposed the PicoRad collectors to an uncontrolled radon atmosphere for conducting validity evaluation. The radon concentration results obtained by the PicoRad collectors using the semi-empirical equation were observed to be in good agreement with the conventional true radon concentration value. It denoted the optimal value of a quantity determined using a reference instrument. These experiments revealed that different values were required for the factors of the conversion equation of each radon collector lot with a different expiration date.
Environmentally Friendly Measurement of Airborne Radon Using a Nonvolatile Liquid Scintillation Absorbent
Authors: Takahisa Kato, Miroslaw Janik, Reiko Kanda, Tetsuo Ishikawa, Masaya Kawase, Takuo Kawamoto
Journal: Health Physics
Volume: 115
Issue: 2
Pages: 203-211
Year: 2018
Abstract: The practicality of using a liquid scintillation method with a nonvolatile liquid scintillation absorbent for the measurement of airborne 222Rn (radon) in a residence was examined. The relationship between the radioactivity absorbed by the liquid scintillation absorbent and the radon concentration in the air was investigated in a calibrated walk-in radon chamber. The equivalent radioactivity of radon was calculated for 214Po radioactivity immediately after radioactive equilibrium was attained using successive decay equations via alpha-particle spectrometry based on the 1 h, indirect, selective measurement of the 214Po alpha-particle spectrum generated after sampling radon. We confirmed that the amounts of radon absorbed in the liquid scintillation absorbent were proportional to the radon concentration in the air. The calibration curve that exhibited reliable quantitative linearity from 500 to 8,000 Bq m−3 in air was extrapolated to the region between 0 and 500 Bq m−3 using the least-squares method with data from 500 to 8,000 Bq m−3. The validity of the extrapolated curve at less than 500 Bq m−3 was confirmed by comparison of the measured radon concentrations in the room and atmosphere with those determined using an existing ionization chamber. Variations in the absorption of radon were observed due to changes in temperature and humidity. The health and environmental safety of nonvolatile liquid scintillation absorbent was also considered.
The presence and dosimetry of radon and thoron in a historical, underground metalliferous mine
Authors: Ross Kleinschmidt, Drew Watson, Miroslaw Janik, Gavin Gillmore
Journal: Journal of Sustainable Mining
Volume: 17
Issue:
Pages: 120-130
Year: 2018
Abstract: A combination of long term passive, and short term active radon-222, radon-220 and respective progeny measurements were conducted in both traverse and longitudinal axes of a historical metalliferous underground mine in North Queensland, Australia. While the passive monitor results provided average radon and thoron air concentrations over periods of 70–90 days, active measurements over a four day period provided significantly more detail into the dynamics of radon and progeny concentrations in the naturally ventilated mine environment. Passive monitor concentrations for radon and thoron ranged between 60 and 390 Bq m−3 (mean: 140 ± 55 Bq m−3 ) and 140 and 2600 Bq m−3 (mean: 1070 ± 510 Bq m−3 ) respectively, with passive thoron progeny monitors providing a mean concentration of 9 ± 5 Bq m−3 EEC. Active measurement mean concentrations for radon, thoron, radon progeny and thoron progeny in the centre of the mine drive were 130 ± 90 Bq m−3 , 300 ± 100 Bq m−3 , 20 ± 20 Bq m−3 EEC and 10 ± 10 Bq m−3 EEC respectively. It was identified that thoron passive detector placement is critical in establishing reliable monitoring data, and is the reason for the discrepancy between the active and passive thoron results in this study. Site specific progeny measurements are required for the accurate estimation of dose to persons entering the mine. Based on short term active measurements and passive thoron progeny monitor results, the dose contribution from thoron and progeny in the mine was observed to contribute up to 80% of the total radon/thoron inhalation dose, and therefore should not be underestimated in monitoring programs under similar conditions.
The screening indoor radon and preliminary study of indoor thoron concentration levels in Kuwait
Authors: M. Janik, D. Al-Azmi, SK. Sahoo
Journal: Radiation Protection Dosimetry
Volume: 181
Issue: 3
Pages: 246-254
Year: 2018
Abstract: Indoor measurements of radon and thoron in Kuwait were conducted during the years 2015 and 2016. In this study, 65 dwellings were selected for the long-term radon–thoron survey using passive nuclear track monitors. The monitors (at least one) were used at various locations in the dwellings for 83–306 days. Some measurements were also repeated at the same locations in different seasons. This current study is a preliminary thoron survey with relatively small sample size. The results showed that the range of thoron concentration was from below the lower limit of detection to 35 Bq m−3, whereas the range of radon concentration was within 10–202 Bq m−3. Furthermore, 22% of the radon results exceeded the WHO radon reference level of 100 Bq m−3. The analysis of variance showed a correlation between indoor radon concentration and the season. However, the thoron measurements were rather limited and the values were low. In addition, the relationship was investigated between radon and thoron concentrations involving the floor levels and the type of ventilation systems used.
Machine learning methods as a tool to analyse incomplete or irregularly sampled radon time series data
Authors: M. Janik, P. Bossew, O. Kurihara
Journal: Science of The Total Environment
Volume: 630
Issue:
Pages: 1155-1167
Year: 2018
Abstract: Machine learning is a class of statistical techniques which has proven to be a powerful tool for modelling the behaviour of complex systems, in which response quantities depend on assumed controls or predictors in a complicated way. In this paper, as our first purpose, we propose the application of machine learning to reconstruct incomplete or irregularly sampled data of time series indoor radon (222Rn). The physical assumption underlying the modelling is that Rn concentration in the air is controlled by environmental variables such as air temperature and pressure. The algorithms “learn” from complete sections of multivariate series, derive a dependence model and apply it to sections where the controls are available, but not the response (Rn), and in this way complete the Rn series. Three machine learning techniques are applied in this study, namely random forest, its extension called the gradient boosting machine and deep learning. For a comparison, we apply the classical multiple regression in a generalized linear model version. Performance of the models is evaluated through different metrics. The performance of the gradient boosting machine is found to be superior to that of the other techniques. By applying learning machines, we show, as our second purpose, that missing data or periods of Rn series data can be reconstructed and resampled on a regular grid reasonably, if data of appropriate physical controls are available. The techniques also identify to which degree the assumed controls contribute to imputing missing Rn values. Our third purpose, though no less important from the viewpoint of physics, is identifying to which degree physical, in this case environmental variables, are relevant as Rn predictors, or in other words, which predictors explain most of the temporal variability of Rn. We show that variables which contribute most to the Rn series reconstruction, are temperature, relative humidity and day of the year. The first two are physical predictors, while “day of the year” is a statistical proxy or surrogate for missing or unknown predictors.
Intercomparisons Exercises of Radon and Thoron Monitors Provided by Four Laboratories: A Review
Authors: Miroslaw JANIK
Journal: Japanese Journal of Health Physics
Volume: 52
Issue: 2
Pages: 114-121
Year: 2017
Abstract: Indoor radon and thoron concentration measurements have been intensively carried out since the 1980s for assessment of radiation doses to workers and the general public. For example, the European Union countries established reference levels for indoor radon concentration in relation to national action plans to address long-term risk from radon exposures. Measurements done using a reliable method are the only way to investigate radon concentration levels. In order to ensure the quality of measurements, intercomparisons among laboratories are performed, as one verification method. The primary purpose of this paper is to provide a concise review of intercomparisons of radon and thoron monitors carried out by four institutions: NIRS (Japan), PHE (UK), BfS (Germany) and SURO (Czech Republic). The different measurement set-ups, evaluation methods and statistical treatments utilized by those institutions are described.
An international cooperation by using an all-encompassing passive radon monitor
Authors: L. Tommasino, J. Chen, R. Falcomer, M. Janik, R. Kanda, F. DeFelice, F. Cardellini, R. Trevisi, F. Leonardi, M. Magnoni, E. Chiaberto, G. Agnesod, M. Faure Ragani, G. Espinosa, J
Journal: Radiation Protection Dosimetry
Volume: 177
Issue: 1-2
Pages: 12-15
Year: 2017
Abstract: The recently developed radon film-badge makes it possible to measure radon indoors, in soil, in water and/or in aqueous media (e.g. mud). As a result of its wide response linearity, this monitor has been successfully used to measure radon in-water with concentrations from 10 to ~10 000 Bq/L. By exploiting the unique characteristics of this badge, a mini-survey has been carried out by Health Canada in which radon in water was measured from 12 private wells, as well as in tap water originating from the Ottawa River. Due to the widespread interest of different laboratories in using these passive monitors, laboratories were provided with plastic films to construct their own badges by using in-house CR-39 detectors. Monitors were then irradiated by a known radon concentration at the National Institute of Radiation Metrology (ENEA)'s radon chamber and sent back to each laboratory for processing and counting. Even though these laboratories have been using different etching- and counting-procedures, the film-badge responses varied only within ~12%.
Optimization of the Timepix chip to measurement of radon, thoron and their progenies
Authors: Miroslaw Janik, Ondrej Ploc, Michael Fiederle, Simon Procz, Norbert Kavasi
Journal: Applied Radiation and Isotopes
Volume: 107
Issue:
Pages: 220-224
Year: 2016
Abstract: Radon and thoron as well as their short-lived progenies are decay products of the radium and thorium series decays. They are the most important radionuclide elements with respect to public exposure. To utilize the semiconductor pixel radiation Timepix chip for the measurement of active and real-time alpha particles from radon, thoron and their progenies, it is necessary to check the registration and visualization of the chip. An energy check for radon, thoron and their progenies, as well as for 241Am and210Po sources, was performed using the radon and thoron chambers at NIRS (National Institute of Radiological Sciences). The check found an energy resolution of 200 keV with a 14% efficiency as well as a linear dependency between the channel number (cluster volume) and the energy. The coefficient of determination r2 of 0.99 for the range of 5 to 9 MeV was calculated. In addition, an offset for specific Timepix configurations between pre-calibration for low energy from 6 to 60 keV, and the actual calibration for alpha particles with energies from 4000 to 9000 keV, was detected.
An intercomparison done at NIRS, Japan on continuous monitors for measuring 220Rn concentration
Authors: Atsuyuki Sorimachi, Miroslaw Janik, Shinji Tokonami, Tetsuo Ishikawa
Journal: Applied Radiation and Isotopes
Volume: 107
Issue:
Pages: 145-151
Year: 2016
Abstract: An intercomparison for continuous monitors that measure thoron (220Rn) concentration was carried out using a 220Rn chamber of National Institute of Radiological Sciences (NIRS), Japan; eleven 220Rn monitors (four types) from nine laboratories were evaluated. The 220Rn detection principle was the same for the eleven instruments and one reference instrument, which were commercially available silicon semiconductor detectors using an electrostatic collection method. The intercomparison results showed that there was a negative deviation of more than 30% in measured 220Rn concentrations given by the laboratories relative to the reference values, which were obtained by making a decay-correction during the travel of 220Rn through the sampling assembly (sample tube, filter and drying unit) and using a calibration factor. In order to elucidate the reason for this and then to investigate factors that affect the 220Rn concentration measured with the monitors. As a result, it was necessary to make the decay-correction, in particular, when using a drying unit with a large inner volume and to use the calibration factor in order to better estimate the 220Rn concentration. It was also found to be better to determine a calibration factor inherent to an individual monitor, because the calibration factor values ranged from 0.75 to 2.32, depending on the flow rate of the monitor pump (0.37–1.02 L min−1). It was concluded from this study that a periodical calibration of the monitor and a check of the monitor flow rate during measurements are necessary to maintain a consistent quality level of the 220Rn measurement.
Analysis of simultaneous time series of indoor, outdoor and soil air radon concentrations, meteorological and seismic data
Authors: Miroslaw Janik, Peter Bossew
Journal: Nukleonika
Volume: 61
Issue: 3
Pages: 295-302
Year: 2016
Abstract: It is well known that the temporal dynamic of indoor and outdoor radon concentrations show complexpatterns, which are partly not easy to interpret. Clearly, for physical reasons, they must be related to possiblyvariable conditions of radon generation, migration and atmospheric dispersion and accumulation. The aim ofthis study was to analyse long-time series of simultaneously measured indoor and outdoor radon concentrations,together with environmental quantities, which may act as control variables of Rn. The study was performed inChiba, Japan, using two ionization chambers for parallel indoor and outdoor radon concentrations measure-ments over 4 years. Meteorological and seismic data were obtained from the Japan Metrological Agency (JMA).
Measurement of radon in air using a radon-218Po calibration curve determined by an absorptive non-volatile liquid scintillator
Authors: Takahisa Kato, Miroslaw Janik, Reiko Kanda, Tetsuo Ishikawa, Masaya Kawase, Takuo Kawamoto
Journal: Radiation Measurements
Volume: 95
Issue:
Pages: 25-30
Year: 2016
Abstract: This work reports a novel method for determining 222Rn (radon) in air using a radon-218Po calibration curve constructed by an absorbable non-volatile liquid scintillator (NVLS). The ability of this method to detect low natural concentrations of radon was confirmed from linear extrapolation of the curve between 500 and 8000 Bq/m3. The calibration curve was created from data obtained from measurements performed in a radon calibration chamber at the National Institute of Radiological Science (NIRS) by using the least-squares method. The line had high precision and stability, and the required detection time was less than that of 214Po. An absorptive NVLS was used to collect radon and was found to be highly advantageous for α-spectrometry liquid scintillation measurements. Variations of the Ostwald coefficient due to changes in temperature and humidity, which affect radon absorption, were investigated and discussed.
Influence of humidity on radon and thoron exhalation rates from building materials
Authors: M Janik, Y Omori, H Yonehara
Journal: Applied Radiation and Isotopes
Volume: 95
Issue:
Pages: 102-107
Year: 2015
Abstract: The contributions of radon and thoron from building materials to total radon (thoron) entry rates in dwellings range from almost zero to several percent. It is necessary to measure radon and thoron exhalation rates, among other things, to assess the radiological hazard to human health in a living environment. Brick and granite specimens were used to study the changes of these rates as a function of the relative and absolute humidities. Measurement results showed that radon and thoron exhalation rates change to humidity with the same trends as well as effective dose could be changed by the factor of 2 due to this.
Radon-thoron discriminative measurements in the high natural radiation areas of southwestern Cameroon
Authors: Shinji Tokonami, Miroslaw Janik, Bineng Guillaume Samuel, Ndjana Nkoulou II Joseph Emmanuel
Journal: Journal of Environmental Radioactivity
Volume: 150
Issue:
Pages: 242-246
Year: 2015
Abstract: Although indoor radon was initially measured in the uranium regions of Poli and Lolodorf using Electret Ionization Chambers, discriminative RADUET detectors were deployed in 70 houses of the high natural radiation areas of Bikoue and Ngombas in the uranium region of Lolodorf in Southwestern Cameroon. Radon and thoron concentrations were determined using Image-J and Microscope Methods for track evaluation. Radon and thoron concentrations follow lognormal distributions and ranged respectively from 27 ± 26 to 937 ± 5 Bq m−3 and from 48 ± 40 to 700 ± 128 Bq m−3. The arithmetic means of radon and thoron concentrations were found to be 92 ± 3 Bq m−3 and 260 ± 13 Bq m−3. Less than 2% of houses have indoor radon above the reference level of 300 Bq m−3 and 30% of houses have thoron concentrations above 300 Bq m−3. Inhalation doses due to radon and thoron range respectively between 0.6–17.7 mSv yr−1 and 0.2–3 mSv yr−1 with the mean values of 1.4 mSv yr−1 and 1 mSv yr−1. The contribution of indoor thoron to the total inhalation dose ranges between 15%- 78.5% with the mean value of 47%. Thus thoron cannot be neglected when assessing radiation dose.
The most recent international intercomparisons of radon and thoron monitors with the NIRS radon and thoron chambers
Authors: M Janik, H Yonehara
Journal: Radiation Protection Dosimetry
Volume: 164
Issue: 4
Pages: 595-600
Year: 2015
Abstract: The fifth international intercomparison for radon and fourth for thoron monitors were conducted at National Institute of Radiological Sciences (Japan) with the radon and thoron chambers. The tests were made under two different exposures to radon and two exposures (in two rounds due to limited space in the thoron chamber) to thoron. In these most recent intercomparisons, two new graphical methods recommended by the ISO standard, Mandel's h statistic and the Youden plot, were implemented to evaluate the consistency between laboratories and within laboratories. The presented data indicated that the performance quality of laboratories for radon measurement as expressed by the percentage difference parameter has been stable since the first international intercomparison for passive monitors carried out in 2007, and it amounted to around 50 for 10 % of the difference from the reference value. The thoron exercise showed that further development and additional studies to improve its measuring methods and reliability are needed.
Novel method for estimation of the indoor-to-outdoor airborne radioactivity ratio following the Fukushima Daiichi Nuclear Power Plant accident
Authors: Yanliang Tan, Tetsuo Ishikawa, Miroslaw Janik, Shinji Tokonami, Masahiro Hosoda, Atsuyuki Sorimachi, Kimberlee Kearfott
Journal: Science of the Total Environment
Volume: 536
Issue:
Pages: 25-30
Year: 2015
Abstract: The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan resulted in significant releases of fission products. While substantial data exist concerning outdoor air radioactivity following the accident, the resulting indoor radioactivity remains pure speculation without a proper method for estimating the ratio of the indoor to outdoor airborne radioactivity, termed the airborne sheltering factor (ASF). Lacking a meaningful value of the ASF, it is difficult to assess the inhalation doses to residents and evacuees even when outdoor radionuclide concentrations are available. A simple model was developed and the key parameters needed to estimate the ASF were obtained through data fitting of selected indoor and outdoor airborne radioactivity measurement data obtained following the accident at a single location. Using the new model with values of the air exchange rate, interior air volume, and the inner surface area of the dwellings, the ASF can be estimated for a variety of dwelling types. Assessment of the inhalation dose to individuals readily follows from the value of the ASF, the person's indoor occupancy factor, and the measured outdoor radioactivity concentration.
Simultaneous sampling of indoor and outdoor airborne radioactivity after the Fukushima Daiichi nuclear power plant accident
Authors: Tetsuo Ishikawa, Atsuyuki Sorimachi, Hideki Arae, Sarata Kumar Sahoo, Miroslaw Janik, Masahiro Hosoda, Shinji Tokonami
Journal: Environmental Science & Technology
Volume: 48
Issue: 4
Pages: 2430-2435
Year: 2014
Abstract: Several studies have estimated inhalation doses for the public because of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Most of them were based on measurement of radioactivity in outdoor air and included the assumption that people stayed outdoors all day. Although this assumption gives a conservative estimate, it is not realistic. The “air decontamination factor” (ratio of indoor to outdoor air radionuclide concentrations) was estimated from simultaneous sampling of radioactivity in both inside and outside air of one building. The building was a workplace and located at the National Institute of Radiological Sciences (NIRS) in Chiba Prefecture, Japan. Aerosol-associated radioactive materials in air were collected onto filters, and the filters were analyzed by γ spectrometry at NIRS. The filter sampling was started on March 15, 2011 and was continued for more than 1 year. Several radionuclides, such as 131I, 134Cs, and 137Cs were found by measuring the filters with a germanium detector. The air decontamination factor was around 0.64 for particulate 131I and 0.58 for 137Cs. These values could give implications for the ratio of indoor to outdoor radionuclide concentrations after the FDNPP accident for a similar type of building.
Invited Article: In situ comparison of passive radon-thoron discriminative monitors at subsurface workplaces in Hungary
Authors: Norbert Kávási, Tamás Vigh, Csaba Németh, Tetsuo Ishikawa, Yasutaka Omori, Miroslaw Janik, Hidenori Yonehara
Journal: Review of Scientific Instruments
Volume: 85
Issue: 2
Pages:
Year: 2014
Abstract: During a one-year long measurement period, radon and thoron data obtained by two different passive radon-thoron discriminative monitors were compared at subsurface workplaces in Hungary, such as mines (bauxite and manganese ore) and caves (medical and touristic). These workplaces have special environmental conditions, such as, stable and high relative humidity (100%), relatively stable temperature (12°C–21°C), low or high wind speed (max. 2.4 m s−1) and low or elevated aerosol concentration (130–60 000 particles m−3). The measured radon and thoron concentrations fluctuated in a wide range among the different workplaces. The respective annual average radon concentrations and their standard deviations (in brackets) measured by the passive radon-thoron discriminative monitor with cellulose filter (CF) and the passive radon-thoron discriminative monitor with sponge filter (SF) were: 350(321) Bq m−3 and 550(497) Bq m−3 in the bauxite mine; 887(604) Bq m−3 and 1258(788) Bq m−3 in the manganese ore mine; 2510(2341) Bq m−3 and 3403(3075) Bq m−3 in the medical cave (Hospital Cave of Tapolca); and 6239(2057) Bq m−3 and 8512(1955) Bq m−3 in the touristic cave (Lake Cave of Tapolca). The respective average thoron concentrations and their standard deviation (in brackets) measured by CF and SF monitors were: 154(210) Bq m−3 and 161(148) Bq m−3 in the bauxite mine; 187(191) Bq m−3 and 117(147) Bq m−3 in the manganese-ore mine; 360(524) Bq m−3 and 371(789) Bq m−3 in the medical cave (Hospital Cave of Tapolca); and 1420(1184) Bq m−3 and 1462(3655) Bq m−3 in the touristic cave (Lake Cave of Tapolca). Under these circumstances, comparison of the radon data for the SF and CF monitors showed the former were consistently 51% higher in the bauxite mine, 38% higher in the manganese ore mine, and 34% higher in the caves. Consequently, correction is required on previously obtained radon data acquired by CF monitors at subsurface workplaces to gain comparable data for SF monitors. In the case of thoron, the data were unreliable and no significant tendency was seen during the comparison therefore comparison of previously obtained thoron data acquired by either CF or SF is doubtful. There was probable influence by relative humidity on the detection response; however, the effects of the high wind speed and elevated aerosol concentration could not be excluded. The results of this study call attention to the importance of calibration under extreme environmental conditions and the need for using reliable radon-thoron monitors for subsurface workplaces.
Preface: Radon-thoron instrumentation and measurement
Authors: Miroslaw Janik, Norbert Kavasi, James R Matey
Journal: Review of Scientific Instruments
Volume: 85
Issue: 2
Pages:
Year: 2014
Abstract: The noble gases conventionally referred to as radon and thoron are both isotopes of the radioactive element radon(symbol Rn, atomic number 86). There are at least 36 isotopes of radon that have been identified and characterized. The two longest lived and most important isotopes are: 222Rn: 3.82 days, 238U decay chain,conventionally called radon; 220Rn: 55.6 seconds, 232Th decay chain, conventionally called thoron. These isotopes are both produced (primarily) by alpha decay from corresponding isotopes of radium. These isotopes and means for measuring them are of great practical importance because these isotopes are important sources of radiation exposure in the environment – radon isotopesare continuously produced by the decay of radioactive materials in the soil, rocks, and building materials around us. These isotopes contribute to radiation exposure in environments as diverse as mines and houses. One effect of exposure – lungcancer – was noted in mine workers long before we understood the mechanisms of the effect – or even knew of the existence of radioactivity. Becker reviewed the history of environmental radon in his 2003 paper;1 he provided examples tracing likely effects of radon exposure back into the 13th century and he suggested that the earliest measurements of indoor radon were carried out by Schmidt in Joachimstall on the German/Czech border around 1907. In the latter part of the 20th century, radon became a concern in many regions of the world – a prominent example is the Reading Prong region of the United States which was the subject of much discussion in the popular press in the 1980–1990s. Though primary interest had long been in radon, in recent years, investigations have shown that the dose from environmental thoron and its progeny may account for up to 10% of the overall dose from environmental radon. Hence both of these isotopes are important. This special issue presents advances in the instrumentation and measurement science associated with radon and thoron metrology. The papers discuss the interaction of radon and thoron measurements with other environmental parameters, including pressure, temperature, humidity, and CO2concentration as well as the applicability of various types of instrumentation – track detectors,activated carbon detectors, electret detectors, and photo-diode detectors – in different settings. These papers are an example of a new feature for Review of Scientific Instruments: a short collection of papers on a single topic, headed by one or more invited papers, a mini-special-issue. Anyone interested in organizing future short collections should contact the editor in chief directly at the RSI editorial office: rsieo@aip.org.
Invited Article: Radon and thoron intercomparison experiments for integrated monitors at NIRS, Japan
Authors: M Janik, T Ishikawa, Y Omori, N Kavasi
Journal: Review of Scientific Instruments
Volume: 85
Issue: 2
Pages:
Year: 2014
Abstract: Inhalation of radon (222Rn) and its short-lived decay products and of products of the thoron (220Rn) series accounts for more than half of the effective dose from natural radiation sources. At this time, many countries have begun large-scale radon and thoron surveys and many different measurement methods and instruments are used in these studies. Consequently, it is necessary to improve and standardize technical methods of measurements and to verify quality assurance by intercomparisons between laboratories. Four international intercomparisons for passive integrating radon and thoron monitors were conducted at the NIRS (National Institute of Radiological Sciences, Japan). Radon exercises were carried out in the 24.4 m3 inner volume walk-in radon chamber that has systems to control radon concentration, temperature, and humidity. Moreover, the NIRS thoron chamber with a 150 dm3 inner volume was utilized to provide three thoron intercomparisons. At present, the NIRS is the only laboratory world-wide that has carried out periodic thoron intercomparison of passive monitors. Fifty laboratories from 26 countries participated in the radon intercomparison, using six types of detectors (charcoal, CR-39, LR 115, polycarbonate film, electret plate, and silicon photodiode). Eighteen laboratories from 12 countries participated in the thoron intercomparisons, using two etch-track types (CR-39 and polycarbonate) detectors. The tests were made under one to three different exposures to radon and thoron. The data presented in this paper indicated that the performance quality of laboratories for radon measurement has been gradually increasing. Results of thoron exercises showed that the quality for thoron measurements still needs further development and additional studies are needed to improve its measuring methods. The present paper provides a summary of all radon and thoron international intercomparisons done at NIRS from 2007 to date and it describes the present status on radon and thoron passive, one-time cycle monitors.
Comparative analysis of radon, thoron and thoron progeny concentration measurements
Authors: Miroslaw Janik, Shinji Tokonami, Chutima Kranrod, Atsuyuki Sorimachi, Tetsuo Ishikawa, Masahiro Hosoda, James Mclaughlin, Byung-Uck Chang, Yong Jae Kim
Journal: Journal of Radiation Research
Volume: 54
Issue: 4
Pages: 597-610
Year: 2013
Abstract: This study examined correlations between radon, thoron and thoron progeny concentrations based on surveys conducted in several different countries. For this purpose, passive detectors developed or modified by the National Institute of Radiological Sciences (NIRS) were used. Radon and thoron concentrations were measured using passive discriminative radon-thoron detectors. Thoron progeny measurements were conducted using the NIRS-modified detector, originally developed by Zhuo and Iida. Weak correlations were found between radon and thoron as well as between thoron and thoron progeny. The statistical evaluation showed that attention should be paid to the thoron equilibrium factor for calculation of thoron progeny concentrations based on thoron measurements. In addition, this evaluation indicated that radon, thoron and thoron progeny were independent parameters, so it would be difficult to estimate the concentration of one from those of the others.
Radon concentration of outdoor air: measured by an ionization chamber for radioisotope monitoring system at radioisotope institute
Authors: Yukari Tajika, Yumi Yasuoka, Hiroyuki Nagahama, Toshiyuki Suzuki, Yoshimi Homma, Tetsuo Ishikawa, Shinji Tokonami, Takahiro Mukai, Miroslaw Janik, Atsuyuki Sorimachi, Masahiro Ho
Journal: Journal of Radioanalytical and Nuclear Chemistry
Volume: 295
Issue:
Pages: 1709-1714
Year: 2013
Abstract: Gas-flow ionization chambers for radioisotope (RI) monitoring systems at RI institutes throughout Japan are commonly used to measure RIs which leak from the RI institutes. Before the Japan’s 2011 Tohoku earthquake [11 March 2011, moment magnitude (M w) 9.0], ionization current data measured with a gas-flow ionization chamber at the RI institute of Fukushima Medical University were found to change. The question we must raise is whether the variation ionization current can be considered to the variation of outdoor radon concentration. The conversion factors (from ionization current to radon concentration in air) of the gas-flow ionization chamber can be obtained by measuring four levels of radon concentration (outdoor air, indoor air, high level and radon-free gas) with an AlphaGUARD monitor and the chamber itself. The two gas-flow ionization chambers consist of the air intake and terminal exhaust duct of the RI institute. It was found that the radon concentration in the exhaust air was the same as that in the air intake. This study provided evidence that variations of outdoor radon concentration could be determined using gas-flow ionization chambers for RI monitoring systems.
Technical report on the 4th international intercomparisons for integrating radon/thoron detectors with the NIRS radon/thoron chambers
Authors: M Janik, T Ishikawa, Y Omori, N Kavasi
Journal: NIRS
Volume: 0
Issue:
Pages:
Year: 2012
Abstract: Technical report on the 4th international intercomparisons for integrating radon/thoron detectors with the NIRS radon/thoron chambers
Intercomparison measurements of 222Rn concentration in water samples in Poland
Authors: Krzysztof Kozak, Beata Kozłowska, Tadeusz A Przylibski, Jadwiga Mazur, Anna Adamczyk-Lorenc, Kalina Mamont-Cieśla, Olga Stawarz, Jerzy Dorda, Barbara Kłos, Mirosław Janik, Elżbie
Journal: Radiation Measurements
Volume: 47
Issue: 1
Pages: 89-95
Year: 2012
Abstract: The paper presents the results of intercalibration measurements of 222Rn concentration in water samples. The aim of the experiments was to evaluate the different measurement methods of radon determination in water samples performed by eleven laboratories in Poland and to test these methods in field work. In the years 2001–2003 three national intercomparison experiments were organized. The results allowed the participating laboratories to improve their measurement methodologies and to achieve better, i.e. more convergent results of determining radon concentration in water samples. The results show that the use of liquid-scintillation technique seems to be the best measurement method. It should be emphasized that comparative experiments are essential for all laboratories and they should be carried out as often as possible, based both on prepared samples with known concentration values of 222Rn and natural water samples, the most commonly used in laboratory practice.
Determination of thoron equilibrium factor from simultaneous long-term thoron and its progeny measurements
Authors: Jing Chen, Deborah Moir, Atsuyuki Sorimachi, Miroslaw Janik, Shinji Tokonami
Journal: Radiation Protection Dosimetry
Volume: 149
Issue: 2
Pages: 155-158
Year: 2012
Abstract: With 3-month simultaneous measurements of thoron and its progeny concentrations in the lowest floors of 109 homes, the geometric mean (GM) of thoron equilibrium factor was determined to be 0.019 with a geometric standard deviation (GSD) of 3.63. Combined with the analysis from results obtained from a previous study in 138 homes, the GM of thoron equilibrium factor was determined to be 0.022 with a GSD of 3.02. The results indicate that the F value of 0.02 for thoron recommended by UNSCEAR is a reasonable value for those Canadian homes tested.
Levels of thoron and progeny in high background radiation area of southeastern coast of Odisha, India
Authors: RC Ramola, GS Gusain, BS Rautela, D Vidya Sagar, G Prasad, SK Shahoo, T Ishikawa, Y Omori, M Janik, A Sorimachi, S Tokonami
Journal: Radiation Protection Dosimetry
Volume: 152
Issue: 1-3
Pages: 62-65
Year: 2012
Abstract: Exposure to radon, 222Rn, is assumed to be the most significant source of natural radiation to human beings in most cases. It is thought that radon and its progeny are major factors that cause cancer. The presence of thoron, 220Rn, was often neglected because it was considered that the quantity of thoron in the environment is less than that of radon. However, recent studies have shown that a high thoron concentration was found in some regions and the exposure to 220Rn and its progeny can equal or several time exceed that of 220Rn and its progeny. The results of thoron and its progeny measurements in the houses of high background radiation area (HBRA) of the southeastern coast of Odisha, India presented here. This area is one of the high background radiation areas in India with a large deposit of monazite sand which is the probable source of thoron. Both active and passive methods were employed for the measurement of thoron and its progeny in cement, brick and mud houses in the study area. Thoron concentration was measured using RAD-7 and Raduet. A CR-39 track detector was employed for the measurement of environmental thoron progeny, both in active and passive modes. Thoron and its progeny concentrations were found to be comparatively high in the area. A comparison between the results obtained with various techniques is presented in this paper.
Determination of the minimum measurement time for estimating long-term mean radon concentration
Authors: M Janik, J Łoskiewicz, S Tokonami, K Kozak, J Mazur, T Ishikawa
Journal: Radiation Protection Dosimetry
Volume: 152
Issue: 1-3
Pages: 168-173
Year: 2012
Abstract: Radon measurements, as do any measurements, include errors in their readings. The relative values of such errors depend principally on the measurement methods used, the radon concentration to be measured and the duration of the measurements. Typical exposure times for radon surveys using passive detectors [nuclear track detectors, activated charcoal, electrostatic (E-perm), etc.)] may extend from a few days to months, whereas, in the case of screening methods utilising active radon monitors (AlphaGUARD, RAD7, EQF, etc.), the measurements may be completed quickly within a few hours to a few days. Thus, the latter may have relatively large error values, which affect the measurement accuracy significantly compared with the former measurements made over long time periods. The method presented in this paper examines the uncertainty of a short-term radon measurement as an estimate of the long-term mean and suggests a minimum measurement time to achieve a given margin of uncertainty of that estimate.
Effects of air exchange property of passive-type radon–thoron discriminative detectors on performance of radon and thoron measurements
Authors: Y Omori, M Janik, A Sorimachi, T Ishikawa, S Tokonami
Journal: Radiation Protection Dosimetry
Volume: 152
Issue: 1-3
Pages: 140-145
Year: 2012
Abstract: Pairs of diffusion chambers with different air exchange rates are used in a large-scale survey to determine radon and thoron, separately. When they are enclosed in radon-proof bags for keeping after the exposure, since radon does not escape out immediately from the low-diffusion chamber, it leads to further exposure in the bags and disturbs the estimation of radon and thoron concentrations. In this study, the effects of the different air exchange properties of the radon–thoron discriminative detectors with CR-39 chips on the estimations of radon and thoron concentrations were investigated. The commercially available and frequently used detectors, Raduet, are examined in this study. The result shows that radon escapes out in 10 h. When degassing is not enough after the exposure in a calibration experiment or high-background radiation area, the residual radon causes the overestimation of the radon concentration and increase in the uncertainty in the thoron concentration, i.e. a low-performance quality of radon and thoron measurements.
Thoron experimental room at the national institute of radiological sciences (NIRS), Japan
Authors: N Kavasi, M Janik, G Prasad, Y Omori, T Ishikawa, H Yonehara
Journal: Radiation Protection Dosimetry
Volume: 152
Issue: 1-3
Pages: 150-153
Year: 2012
Abstract: A new thoron (220Rn) experimental room (TER) was established at National Institute of Radiological Sciences in 2011 to respond to the appearance of new passive devices for 220Rn and its progeny (212Pb, 212Bi) measurement. The room volume is 21.7 m3 with a low air exchange rate, 0.016 h−1. Environmental parameters, such as temperature, relative and absolute humidities, wind speed, aerosol distribution and concentration, are monitored, but not controlled. Commercially available lantern mantles (500 pcs), which can generate maximum concentrations of 6000 Bq m−3 of 220Rn and 2000 Bq m−3 of its progeny, are used as a 220Rn source. Based on preliminary results from the TER, stable and homogenised concentrations of 220Rn and its progeny can be ensured; therefore, in the near future the room will be used for testing measuring instruments.
International symposium on the natural radiation exposures and low-dose radiation epidemiological studies
Authors: Shinji Tokonami, Miroslaw Janik, Jing Chen, Atsuyuki Sorimachi, Tetsuo Ishikawa
Journal: Radiation Protection Dosimetry
Volume: 152
Issue: 1-3
Pages: 1-1
Year: 2012
Abstract: This special issue of Radiation Protection Dosimetry constitutes the Proceedings of the International Symposium on the Natural Radiation Exposures and Low Dose Radiation Epidemiological Studies (NARE2012), organised by the Hirosaki University and National Institute of Radiological Sciences (NIRS), Japan, and held at Hirosaki University, 29 February–3 March 2012. The symposium was supported by the Aomori Prefecture Government as well as the Japan Science and Technology Agency (JST) through the grant-in-aid entitled ‘Construction of Natural Radiation Exposure Study Network’ which commenced in 2009 and was managed by NIRS.
Estimation of radon diffusion coefficients in soil using an updated experimental system
Authors: Ganesh Prasad, Tetsuo Ishikawa, Masahiro Hosoda, Atsuyuki Sorimachi, Miroslaw Janik, Sarata Kumar Sahoo, Shinji Tokonami, Shigeo Uchida
Journal: Review of Scientific Instruments
Volume: 83
Issue: 9
Pages:
Year: 2012
Abstract: Radon diffusion through soil is strongly affected by the degree of water saturation of the soil pores. Methods have been developed by many researchers to measure radon diffusion coefficient. We developed an updated experimental system to estimate radon diffusion coefficients for typical types of soil in Japan and applied it to a typical loam with different water saturation levels (0–0.82). The system consists of a passive-type scintillation cell, soil column, accumulation tank, and radon source. The radon concentration in the accumulation tank is kept stable, and radon diffused through the soil column is continuously measured with the passive-type scintillation cell. We found the radon diffusion coefficients vary from 9.60 × 10−6 m2 s−1 to 1.27 × 10−7 m2 s−1 for the loam samples. Generally, the diffusion coefficients are almost constant for a water saturation range of 0–0.4 and decrease with increasing water saturation from 0.4 to 0.82.
Simultaneous measurement of radon and thoron released from building materials used in Japan
Authors: Nabil M Hassan, Masahiro Hosoda, Kazuki Iwaoka, Atsuyuki Sorimachi, Miroslaw Janik, Chutima Kranrod, Sarata K Sahoo, Tetsuo Ishikawa, Hidenori Yonehara, Masahiro Fukushi, Shinji
Journal: Progress in Nuclear Science and Technology
Volume: 1
Issue:
Pages: 404-407
Year: 2011
Abstract: Common building materials used in constructing dwellings are a major source of radon and thoron gases emanation into the indoor environment. Concentrations of the radionuclides 226Ra and 232Th and radon/thoron exhalation rates are important parameters for characterizing radon and thoron sources in building materials and comparing the relative contribution of different materials to the total radiation dose. In the present study, concentrations of the radionuclides 226Ra, 232Th and 40K in different kinds of granite used as building materials in Japan were determined by γ-ray spectroscopy, and a common hazard index, the radium equivalent index, was evaluated on the basis of those results. Exhalation rates of radon and thoron were measured by using an accumulation chamber equipped with a solid-state alpha particle detector. The influence of chamber leakage and back diffusion time decay constants on radon exhalation rate was also estimated, and the correlations between radon/thoron exhalation rates and their parent nuclide (radium/thorium) concentrations were examined.
The effect of water content on the radon emanation coefficient for some building materials used in Japan
Authors: Nabil M Hassan, Tetsuo Ishikawa, Masahiro Hosoda, Kazuki Iwaoka, Atsuyuki Sorimachi, Sarata K Sahoo, Miroslaw Janik, Chutima Kranrod, Hidenori Yonehara, Masahiro Fukushi, Shinji
Journal: Radiation Measurements
Volume: 46
Issue: 2
Pages: 232-237
Year: 2011
Abstract: Building materials used in Japan were collected from several companies and their radionuclide concentrations were measured. Fifteen granite samples with high activity concentrations were selected for the present study. To investigate the effect of water content on the radon emanation coefficient, the coefficient was measured under 3 different conditions (dry, normal, and wet). The emanation coefficients were then used to calculate the alpha equivalent dose (dose from indoor radon generated from building materials), assuming a simple room model. The radon emanation coefficient for the dry condition ranged from (3.7 ± 0.1)% to (27.2 ± 3.9)%, with an average value of (10.5 ± 1.4)%. The emanation coefficients were 2–5 times that size for the wet condition. Similarly, the alpha dose became larger, owing to its proportion to the emanation coefficient, indicating that water content in building materials is an important factor for the emanation coefficient as well as the radiation dose. The radon exhalation rate was also measured for the dry samples. Radon exhalation rate and radium concentration had a relatively low correlation (R2 = 0.40). However, the correlation between radon exhalation rate and “emanated radon concentration” (radium concentration × emanation coefficient) was much higher (R2 = 0.84). Therefore, emanated radon concentration could be a useful index for exhalation rate and alpha equivalent dose, but radium concentration in building materials alone is not.
An update on thoron exposure in Canada with simultaneous 222Rn and 220Rn measurements in Fredericton and Halifax
Authors: Jing Chen, Deborah Moir, Toon Pronk, Terry Goodwin, Miroslaw Janik, Shinji Tokonami
Journal: Radiation Protection Dosimetry
Volume: 147
Issue: 4
Pages: 541-547
Year: 2011
Abstract: Naturally occurring isotopes of radon in indoor air are identified as the second leading cause of lung cancer after tobacco smoking. Radon-222 (radon gas) and radon-220 (thoron gas) are the most common isotopes of radon. While extensive radon surveys have been conducted, indoor thoron data are very limited. To better assess thoron exposure in Canada, radon/thoron discriminating detectors were deployed in 45 homes in Fredericton and 65 homes in Halifax for a period of 3 months. In this study, radon concentrations ranged from 16 to 1374 Bq m−3 with a geometric mean (GM) of 82 Bq m−3 and a geometric standard deviation (GSD) of 2.56 in Fredericton, and from 4 to 2341 Bq m−3 with a GM of 107 Bq m−3 and a GSD of 3.67 in Halifax. It is estimated that 18 % of Fredericton homes and 32 % of Halifax homes could have radon concentrations above the Canadian indoor radon guideline of 200 Bq m−3. This conclusion is significantly higher than the previous estimates made 30 y ago with short-term radon measurements. Thoron concentrations were below the detection limit in 62 % of homes in both cities. Among the homes with detectable thoron concentrations, the values varied from 12 to 1977 Bq m−3 in Fredericton and from 6 to 206 Bq m−3 in Halifax. The GM and GSD were 86 Bq m−3 and 3.19 for Fredericton, and 35 Bq m−3 and 2.35 for Halifax, respectively. On the basis of these results, together with previous measurements in Ottawa, Winnipeg and the Mont-Laurier region of Quebec, it is estimated that thoron contributes ∼8 % of the radiation dose due to indoor radon exposure in Canada.
Long-term measurements of thoron, its airborne progeny and radon in 205 dwellings in Ireland
Authors: J McLaughlin, M Murray, L Currivan, D Pollard, V Smith, S Tokonami, A Sorimachi, M Janik
Journal: Radiation Protection Dosimetry
Volume: 145
Issue: 2-3
Pages: 189-193
Year: 2011
Abstract: Long-term (circa 3 months) simultaneous measurements of indoor concentrations of thoron gas, airborne thoron progeny and radon were made using passive alpha track detectors in 205 dwellings in Ireland during the period 2007–09. Thoron progeny concentrations were measured using passive deposition monitors designed at the National Institute of Radiological Sciences (NIRS), Japan, whereas thoron gas concentrations were measured using Raduet detectors (Radosys, Budapest). Radon concentrations were measured in these dwellings by means of NRPB/SSI type alpha track radon detectors as normally used by the Radiological Protection Institute of Ireland (RPII). The concentration of thoron gas ranged from <1 to 174 Bq m−3 with an arithmetic mean (AM) of 22 Bq m−3. The concentration of radon gas ranged from 4 to 767 Bq m−3 with an AM of 75 Bq m−3. For radon, the estimated annual doses were 0.1 (min), 19.2 (max) and 1.9 (AM) mSv y−1. The concentration of thoron progeny ranged from <0.1 to 3.8 Bq m−3 [equilibrium equivalent thoron concentration (EETC)] with an AM of 0.47 Bq m−3 (EETC). The corresponding estimated annual doses were 2.9 (max) and 0.35 (mean) mSv y−1. In 14 or 7% of the dwellings, the estimated doses from thoron progeny exceeded those from radon.
Measurements of radon, thoron and their progeny at Rare-Earth Research and Development Center, Thailand
Authors: C Kranrod, S Tokonami, M Janik, A Sorimachi, S Chanyotha, N Kritsananuwat, P SripIoy, C Chayavadhanangkur
Journal: Proceedings of the seventh international conference on high levels of natural radiation and radon areas: abstracts
Volume:
Issue:
Pages:
Year: 2010
Abstract: Radon, thoron and their progeny were measured using active methods at rare-earth research and development center, Phathumthani Province, ThaiIand. The facility consists of the uranium and thorium extraction building, rare-earth extraction building, and monazite storage building. It was found that thoron concentration in all buildings is higher than radon concentration. The highest concentration of radon and thoron were found at the monazite storage building (442 ± 49 Bq m-3 and 5150 ± 168 Bq m-3 respectively). In addition, equilibrium equivalent radon and thoron concentrations in this building were 41 ± 5 and 10 ± 1 Bq m-3.
Radon and thoron levels in high radiation background area of Orissa, India
Authors: A Sorimachi, S Tokonami, SK Sahoo, T Ishikawa, M Janik, M Furukawa, S Akiba, H Yamazawa, J Moriizumi, RC Ramola
Journal: Proceedings of the seventh international conference on high levels of natural radiation and radon areas: abstracts
Volume:
Issue:
Pages:
Year: 2010
Abstract: Measurements of natural radiation were made in the houses of Chhatrapur area of southeastern coastal of Orissa, India, where is one of the high radiation background areas in India. Indoor radon, thoron and their decay products were measured using passive and active techniques. As a result of duration concentrations using an electrostatic collection method, indoor thoron concentrations were observed to be more than 200 Bq m-3. On the other hand, the radon concentrations in all the houses investigated in this study were less than 30 Bq m-3, which was the almost same tendency as a pulse ionization chamber. Thus this investigation showed the thoron concentrations in dwellings seemed to be higher than the values for radon. This study describes radon and thoron levels in dwellings in high radiation background area of Orissa, India.
Thoron and its airborne progeny in Irish dwellings
Authors: JP Mc Laughlin, Michael Murray, Lorraine Currivan, David Pollard, Veronica Smith, Shinji Tokonami, Atsuyuki Sorimachi, Miroslaw Janik
Journal: Proceedings of the Third European IRPA Congress
Volume:
Issue:
Pages: 2607-2612
Year: 2010
Abstract: During the period 2007-2009 long term indoor concentrations of thoron gas and airborne thoron progeny were measured using passive detectors in 205 dwellings in Ireland. Passive alpha track detectors of different types were used to make these measurements in the indoor air over a typical exposure period of at least three months. Thoron concentrations were measured using Raduet detectors supplied by Radosys, Budapest while thoron progeny concentrations were measured using passive detectors designed by the National Institute of Radiological Sciences (NIRS), Chiba, Japan. Radon concentrations were also measured in these dwellings using the standard alpha track detectors employed by the Radiological Protection Institute of Ireland (RPII). The main results obtained are given below. It should be noted that these results are based on the actual measurements made and are not seasonally adjusted. The estimated annual doses for thoron progeny (ThP) and radon (Rn) were calculated using dose conversion factors (DCF). The DCFThP used was based on the dosimetry models of Kendall and Phipps (2007) and of Ishikawa et al (2007). Exposure to indoor air containing thoron decay products at a concentration of 1 Bq/m3 EETC (Equilibrium Equivalent Thoron Concentration) was estimated to result in an annual effective dose of 0.75 mSv. For radon a DCFRn of 1 mSv/year for indoor exposure under standard conditions to 40 Bq/m3 was used.
Quality assurance and quality control for thoron measurement at NIRS
Authors: A Sorimachi, T Ishikawa, M Janik, S Tokonami
Journal: Radiation Protection Dosimetry
Volume: 141
Issue: 4
Pages: 367-370
Year: 2010
Abstract: The National Institute of Radiological Sciences (NIRS) has developed passive radon (222Rn)–thoron (220Rn) discriminative detectors for a large-scale survey and has established a thoron chamber to calibrate such detectors. In order to establish quality assurance and quality control for the 220Rn measurement at NIRS, intercomparison studies have been carried out. The intercomparisons using a scintillation cell method, which has been used as a standard for 220Rn measurement at NIRS, were conducted at New York University (NYU, USA) and Physikalisch-Technische Bundesanstalt (PTB, Germany). As a result, it was found that the result from the NIRS was in good agreement with that from the NYU. On the other hand, it was observed that the relative discrepancy between the 220Rn concentrations from the NIRS and PTB monitors was, on average, >50 %. Using the NIRS 220Rn chamber, the international intercomparison experiment for passive 220Rn detectors started in 2008.
Preliminary indoor thoron measurements in high radiation background area of southeastern coastal Orissa, India
Authors: RC Ramola, G Prasad, GS Gusain, BS Rautela, VM Choubey, D Vidya Sagar, S Tokonami, A Sorimachi, SK Sahoo, M Janik, T Ishikawa
Journal: Radiation Protection Dosimetry
Volume: 141
Issue: 4
Pages: 379-382
Year: 2010
Abstract: This paper presents the preliminary results of radon and thoron measurements in the houses of Chhatrapur area of southeastern coast of Orissa, India. This area is one of the high radiation background radiation areas in India, which consists of monazite sand as the source of thoron. Both active and passive methods were employed for the measurements. Radon and thoron concentrations were measured in the houses of Chhatrapur area using twin cup radon dosemeters, RAD7 and radon–thoron discriminative detector (Raduet). Thoron progeny concentration was also measured in the houses using deposition rate measurements. Radon and thoron concentrations in the houses of study area were found to vary from 8 to 47 Bq m−3 and the below detection level to 77 Bq m−3, respectively. While thoron progeny concentration in these houses ranges between 0.17 and 4.24 Bq m−3, preliminary investigation shows that the thoron concentration is higher than radon concentration in the houses of the study area. The thoron progeny concentration was found to be comparatively higher, which forms a base for further study in the area. The comparison between the results of various techniques is presented in this paper.
Influence of soil environmental parameters on thoron exhalation rate
Authors: M Hosoda, S Tokonami, A Sorimachi, T Ishikawa, SK Sahoo, M Furukawa, Y Shiroma, Y Yasuoka, M Janik, N Kavasi, S Uchida, M Shimo
Journal: Radiation Protection Dosimetry
Volume: 141
Issue: 4
Pages: 420-423
Year: 2010
Abstract: Field measurements of thoron exhalation rates have been carried out using a ZnS(Ag) scintillation detector with an accumulation chamber. The influence of soil surface temperature and moisture saturation on the thoron exhalation rate was observed. When the variation of moisture saturation was small, the soil surface temperature appeared to induce a strong effect on the thoron exhalation rate. On the other hand, when the variation of moisture saturation was large, the influence of moisture saturation appeared to be larger than the soil surface temperature. The number of data ranged over 405, and the median was estimated to be 0.79 Bq m−2 s−1. Dependence of geology on the thoron exhalation rate from the soil surface was obviously found, and a nationwide distribution map of the thoron exhalation rate from the soil surface was drawn by using these data. It was generally high in the southwest region than in the northeast region.
International intercomparisons of integrating radon/thoron detectors with the NIRS radon/thoron chambers
Authors: M Janik, S Tokonami, C Kranrod, A Sorimachi, T Ishikawa, NM Hassan
Journal: Radiation Protection Dosimetry
Volume: 141
Issue: 4
Pages: 436-439
Year: 2010
Abstract: Intercomparisons of radon/thoron detectors play an important role not only for domestic radon/thoron survey but also for international or interregional discussion about radon/thoron mapping in dwellings as well as that in the soil. For these purposes, it is necessary to improve and standardise technical methods of measurement and to verify quality assurance by intercomparisons between laboratories. Therefore, the first thoron international intercomparison was provided at the NIRS (National Institute of Radiological Sciences, Japan) thoron chamber with a 150 dm3 inner volume. In addition, a second intercomparison of radon detectors was conducted at NIRS with a 24.4 m3 inner volume walk-in radon chamber. Only etched-track detectors were used during thoron intercomparison as well as three types for the radon intercomparison: etched-track, charcoal and electret. In general, 45 % results for thoron experiment do not differ more than 20 % from the reference value of thoron concentration and 69 % for radon.
A comparative study of thorium activity in NORM and high background radiation area
Authors: SK Sahoo, T Ishikawa, S Tokonami, A Sorimachi, C Kranrod, M Janik, M Hosoda, NM Hassan, S Chanyotha, VK Parami, H Yonehara, RC Ramola
Journal: Radiation Protection Dosimetry
Volume: 141
Issue: 4
Pages: 416-419
Year: 2010
Abstract: Several industrial processes are known to enrich naturally occurring radioactive materials (NORM). To assess such processes with respect to their radiological relevance, characteristic parameters describing this enrichment will lead to interesting information useful to UNSCEAR. In case of mineral treatment plants, the high temperatures used in smelting and refining processes lead to high concentrations of 238U and 232Th. Also due to thermal power combustion, concentration of U and Th in the fly ash increases manifold. NORM samples were collected from a Thailand mineral treatment plant and Philippine coal-fired thermal power plants for investigation. Some studies are initiated from a high background radiation area near Gopalpur of Orissa state in India. These NORM samples were analysed by gamma-ray spectrometry as well as inductively coupled plasma mass spectrometry. The radioactivity in case of Orissa soil samples is found to be mainly contributed from thorium. This study attempts to evaluate levels of thorium activity in NORM samples.
Separately measuring radon and thoron concentrations exhaled from soil using alphaguard and liquid scintillation counter methods
Authors: Y Yasuoka, A Sorimachi, T Ishikawa, M Hosoda, S Tokonami, N Fukuhori, M Janik
Journal: Radiation Protection Dosimetry
Volume: 141
Issue: 4
Pages: 412-415
Year: 2010
Abstract: It was shown that radon and thoron concentrations exhaled from soil were separately measured using the AlphaGUARD and liquid scintillation counter (LSC) methods. The thoron concentrations from the RAD 7 were used to create the conversion equation to calculate thoron levels with the AlphaGUARD. However, the conversion factor was found to depend on the air flow rate. When air containing thoron of ∼60 kBq m−3 was fed to the scintillation cocktail, thoron and thoron progeny could not be measured with the LSC method. The radon concentration of about 10 kBq m−3 was measured with three methods, first with the LSC method and then with two AlphaGUARDs (one in the diffusion mode and the other in the flow mode (0.5 l min−1)). There were no significant differences between these results. Finally, it was shown that the radon and thoron concentrations in air could be measured with the AlphaGUARD and LSC methods.
Long-term determination of airborne radon progeny concentrations using LR 115 detectors and the effects of thoron
Authors: VWY Choi, CKM Ng, RKK Lam, M Janik, A Sorimachi, C Kranrod, Dragoslav Nikezic, S Tokonami, KN Yu
Journal: Radiation Protection Dosimetry
Volume: 141
Issue: 4
Pages: 404-407
Year: 2010
Abstract: The 'proxy equilibrium factor' (Fp) method has been developed for long-term determination of airborne radon progeny concentrations using LR 115 solid-state nuclear track detectors. In this paper, the effects of 220Rn on the Fp method have been studied. The correction to the track density was related to a parameter α which was the ratio of the sum of activity concentrations of alpha-particle emitting radionuclides in the 220Rn decay chain to the activity concentration of 220Rn alone. Under commonly encountered circumstances, α could not be smaller than 2. An attempt was made to verify this using the exposure chamber at the National Institute of Radiological Sciences (NIRS), Chiba, Japan. A most interesting observation of α < 2 for very high 220Rn concentrations and very low equilibrium factors for 220Rn in the exposure chambers was made. A possible explanation was the substantial deposition of 216Po under the extreme conditions inside the exposure chambers.
Evaluation of Radon Exhalation Rate by Support Tool for Environmental Parameter Estimation (in Japanese)
Authors: Masahiro HOSODA, Shinji TOKONAMI, Tetsuo ISHIKAWA, Sarata K. SAHOO, Atsuyuki SORIMACHI, Miroslaw JANIK, Norbert KAVASI, Shigeo UCHIDA
Journal: Radioisotopes
Volume: 59
Issue: 7
Pages: 423-428
Year: 2010
Abstract: In this study, we applied support tool(Impara) for environmental parameter estimation to evaluation of radon and thoron exhalation rates from soil surface. This support tool was developed for estimation of soil-to-soil solution distribution coefficient(Kd) and soil-to-plant transfer factor(TF). As a result of multiple linear regression analysis, radium content in the soil, emanation coefficient, volumetric water content and soil temperature were important parameters for estimation of radon and thoron exhalation rates from soil surface. Comparisons of measured and estimated radon/thoron exhalation rates showed relatively good agreement.
Report on the First Meeting on "Construction of Natural Radiation Exposure Study Network" by Special Coordination Funds for Promoting Science and Technology of Ministry
Authors: Atsuyuki SORIMACHI, Shinji TOKOMAMI, Miroslaw JANIK, Tetsuo ISHIKAWA, Sarata K. SAHOO, Shinji YOSHINAGA, Hidenori YONEHARA, Kazuo SAKAI, Hiromi YAMAZAWA, Suminori AKIBA, Masahide
Journal: Japanese Journal of Health Physics (保健物理)
Volume: 45
Issue: 1
Pages: 15-18
Year: 2010
Abstract: Report
International intercomparisons of integrating radon detectors in the NIRS radon chamber
Authors: Miroslaw Janik, Shinji Tokonami, Tibor Kovács, Norbert Kávási, Chutima Kranrod, Atsuyuki Sorimachi, Hiroyuki Takahashi, Nobuyuki Miyahara, Tetsuo Ishikawa
Journal: Applied Radiation and Isotopes
Volume: 67
Issue: 9
Pages: 1691-1696
Year: 2009
Abstract: An international intercomparison of integrating detectors was conducted at NIRS (National Institute of Radiological Science, Japan) with a 24.4 m3 inner volume walk-in radon chamber that has systems to control radon concentration, temperature and humidity. During the first intercomparison (05.2007) four groups participated from four countries and for the second intercomparison (10.2007) 17 participants were involved from 11 countries. Most of detectors are in good agreement with each other when compared to the radon level provided by the radon chamber. It appeared that the 70% of detectors are unified within the 20% margin of uncertainty.
Mitigation of the effective dose of radon decay products through the use of an air cleaner in a dwelling in Okinawa, Japan
Authors: Chutima Kranrod, Shinji Tokonami, Tetsuo Ishikawa, Atsuyuki Sorimachi, Miroslaw Janik, Reina Shingaki, Masahide Furukawa, Supitcha Chanyotha, Nares Chankow
Journal: Applied Radiation and Isotopes
Volume: 67
Issue: 6
Pages: 1127-1132
Year: 2009
Abstract: Field measurements were conducted to assess the effects of an air cleaner on radon mitigation in a dwelling with a high radon concentration in Okinawa, Japan. The measurements included indoor radon concentration, individual radon progeny concentration, equilibrium equivalent concentration of radon (EECRn), unattached fraction, and size distribution of aerosol-attached radon progeny. These measurements were conducted in a 74 m3 room with/without the use of an air cleaner. The results showed that the mean radon concentration during the measurement was quite high (301 Bq m−3). The operation of air cleaner decreased the radon progeny activity concentration, EECRn and equilibrium factor by 33%, 57% and 71%, respectively, whereas the unattached fraction increased by 174%. In addition, the activity concentration of attached radon progeny in the accumulation mode (50–2000 nm) was obviously deceased by 42%, when the air cleaner was operated. According to dosimetric calculations, the operation of air cleaner reduced the effective dose due to radon progeny by about 50%.
Natural and artificial sources of radioactivity in Poland
Authors: Miroslaw Janik, Shinji Tokonami
Journal: Japanese Journal of Health Physics
Volume: 44
Issue: 1
Pages: 116-121
Year: 2009
Abstract: In Poland there are some special regions in which the natural background radiation is obviously higher than in neighboring areas. This paper presents a review of recent radiation measurements taken in the Polish environment. Natural sources including radon, potassium, uranium and thorium as well as artificial sources such as cesium are characterized. Their contribution to the annual radioactivity dose rate is described.
Field experience with soil gas mapping using Japanese passive radon/thoron discriminative detectors for comparing high and low radiation areas in Serbia (Balkan Region)
Authors: Zora S Žunić, Miroslaw Janik, Shinji Tokonami, Nenad Veselinović, Ilia V Yarmoshenko, Michael Zhukovsky, Tetsuo Ishikawa, Rakesh C Ramola, Giancarlo Ciotoli, Peter Jovanović, Krz
Journal: Journal of Radiation Research
Volume: 50
Issue: 4
Pages: 355-361
Year: 2009
Abstract: Based on results of fieldwork in the Balkan Region of Serbia from 2005 to 2007, soil gas radon and thoron concentrations as well as gamma dose rates were measured. Campaigns were conducted in two different geological regions: Niška Banja, considered a high natural radiation area, and Obrenovac around the TentB Thermal Power Plant (TPP), a low natural radiation area. Radon and thoron gas measurements were made by using two types of Japanese passive radon/thoron detectors, which included GPS data and gamma dose rates. The concentrations of soil radon gas in Niška Banja ranged from 1.8 to 161.1 kBq m–3, whereas the concentrations for soil thoron gas ranged from 0.9 to 23.5 kBq m–3. The gamma dose rates varied from 70 to 320 nGy h–1. In the TentB area, radon concentration was found to range from 0.8 to 24.9 kBq m–3 and thoron from 0.6 to 1.9 kBq m–3. The gamma dose rate ranged from 90 to 130 nGy h–1. In addition, the natural radioactivity of the soil was investigated at the low background area. The radium and thorium contents in collected soil samples ranged from 23 to 58 and 33 to 67 Bq kg–1, respectively. As a result of correlation analyses between the measured values, the highest correlation coefficient (R> 0.95) was found for thorium in the soil and the thoron gas concentration.
Anomalously high radon concentrations in a dwelling in Okinawa, Japan
Authors: Chutima KRANROD, Miroslaw JANIK
Journal: Radioisotopes
Volume: 58
Issue: 12
Pages: 807-813
Year: 2009
Abstract: Short-term measurements of indoor radon concentrations were made in a dwelling in Okinawa, Japan, in which high radon concentrations had been observed in a previous nationwide indoor survey. Measurements were carried out in 4 locations:the bedroom, living room and outdoors. In this study, anomalously high radon concentrations were observed in the 1st-floor bedroom and the mean radon concentration averaged about 400Bq m-3 during the observation period, much higher than Japan's annual average of 15.5Bq m-3. A diurnal pattern of extreme fluctuation was found. Furthermore, there was a noticeable spatial distribution of indoor radon concentrations.
Anomalously High Radon Concentrations in a Dwelling in Okinawa, Japan (沖縄県で観測された室内における高ラドン濃度)
Authors: Atsuyuki SORIMACHI, Chutima KRANROD, Shinji TOKONAMI, Tetsuo ISHIKAWA, Masahiro HOSODA, Miroslaw JANIK, Reina SHINGAKI, Masahide FURUKAWA
Journal: Radioisotopes
Volume: 58
Issue: 12
Pages: 807-813
Year: 2009
Abstract: Short-term measurements of indoor radon concentrations were made in a dwelling in Okinawa, Japan, in which high radon concentrations had been observed in a previous nationwide indoor survey. Measurements were carried out in 4 locations:the bedroom, living room and outdoors. In this study, anomalously high radon concentrations were observed in the 1st-floor bedroom and the mean radon concentration averaged about 400Bq m-3 during the observation period, much higher than Japan's annual average of 15.5Bq m-3. A diurnal pattern of extreme fluctuation was found. Furthermore, there was a noticeable spatial distribution of indoor radon concentrations.
Experimental system to evaluate the effective diffusion coefficient of radon
Authors: Masahiro Hosoda, Shinji Tokonami, Atsuyuki Sorimachi, Miroslaw Janik, Tetsuo Ishikawa, Yoshinori Yatabe, Junya Yamada, Shigeo Uchida
Journal: Review of Scientific Instruments
Volume: 80
Issue: 1
Pages:
Year: 2009
Abstract: The effective diffusion coefficient of radon is a very important factor in estimating the rate of radon exhalation from the ground surface. In this study, we developed an experimental system that overcomes technical problems in previous studies to accurately evaluate the effective diffusion coefficient. The radon source used for this system was the National Institute of Radiological Sciences radon chamber. This chamber is a calibrated international standard facility that can produce stable radon concentrations for long periods of time. Our tests showed that leakage of radon from the system was negligible. After the leakage test, we evaluated the effective diffusion coefficient in free-space and in dry porous materials at porosities of 35% and 45%. To ensure that the porous material in the column was as homogeneous as possible, we filled the column with an artificial soil with controlled grain size and grain composition. The measured values and theoretical calculations agreed well, which indicate that the proposed system can be used to accurately and quickly evaluate the effective diffusion coefficient.
A campaign of discrete radon concentration measurements in soil of Niška Banja town, Serbia
Authors: Zora S Žunić, K Kozak, G Ciotoli, RC Ramola, E Kochowska, Predrag Ujić, I Čeliković, J Mazur, M Janik, A Demajo, A Birovljev, Francesco Bochicchio, Ilia V Yarmoshenko, D Kryeziu,
Journal: Radiation Measurements
Volume: 42
Issue: 10
Pages: 1696-1702
Year: 2007
Abstract: The first radon soil gas survey in Serbia, using passive detectors (SSNTD, CR-39), was carried out in June 2005 at field sites in Niška Banja town. The aim of the survey was to identify risk zones characterised by high levels of this radioactive gas. Radon measurements were made at the depth of 50 cm, in the ground according to a systematic grid pattern. Furthermore, at all 48 measurement points, the surface gamma dose rates in the air was also measured at the same locations and soil samples were collected for gamma spectrometric analysis for the radionuclides 226Ra, 228Th and 40K.
High natural radiation exposure in radon spa areas: a detailed field investigation in Niška Banja (Balkan region)
Authors: Zora S Žunić, I Kobal, Janja Vaupotič, K Kozak, J Mazur, A Birovljev, M Janik, I Čeliković, Predrag Ujić, A Demajo, G Krstić, Bajram Jakupi, Maria Quarto, Francesco Bochicchio
Journal: Journal of Environmental Radioactivity
Volume: 89
Issue: 3
Pages: 249-260
Year: 2006
Abstract: The measurement campaigns have been done in the rural community of Niška Banja, a spa town located in southern Serbia, to evaluate population exposure to natural radioactivity. After a screening survey in 200 houses, annual radon and thoron concentrations were measured in 34 houses, and in 2004 a detailed investigation was carried out at six houses with elevated indoor radon concentrations. The paper presents the results of these detailed measurements. The complementary techniques were applied to determine radon and thoron concentrations in indoor air, in soil gas, radon exhalation from soil, soil permeability, and indoor and outdoor gamma doses. Soil and water samples were collected and analysed in the laboratory. Indoor radon and thoron concentrations were found to be more than 1 kBq m−3 and 200 Bq m−3, respectively. Extremely high concentrations of soil-gas radon (>2000 kBq m−3) and radon exhalation rates (1.5 mBq m−2 s−1) were observed. These results will be utilised to set up the methodology for a more systematic investigation.
Field work in Niska Banja—methods and preliminary results of soil measurements
Authors: J Mazur, K Kozak, M Janik, ZS Žunić, I Kobal, J Vaupotič, I Čeliković, P Ujić, G Krstić, B Jakupi
Journal: Book of abstracts of the second Vinca ECE Lab advanced research international workshop—the new perspectives for thoron survey and dosimetry, Niška Banja
Volume:
Issue:
Pages: 24
Year: 2005
Abstract: One part of field measurements in Niska Banja spa encompassed measurements of radon and thoron concentration in soil gas, radon exhalation rate and soil permeability. A team from Natural Radioactivity Laboratory, Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland, carried out this type of radon investigation. The professional radon monitor AlphaGUARD PQ2000 PRO and the special soil probe (designed and made at IFJ PAN) were applied for the determination of radon and thoron concentration in soil gas and soil permeability. For measurements of radon exhalation rate from soil we used also the AlphaGUARD monitor and the accumulating container, which was put on the soil surface.
Radon concentration in soil gas around local disjunctive tectonic zones in the Krakow area
Authors: J Swakoń, K Kozak, M Paszkowski, R Gradziński, J Łoskiewicz, J Mazur, M Janik, J Bogacz, T Horwacik, P Olko
Journal: Journal of Environmental Radioactivity
Volume: 78
Issue: 2
Pages: 137-149
Year: 2005
Abstract: The purpose of this study was to investigate radon in the vicinity of geologic fault zones within the Krakow region of Poland, and to determine the influence of such formations on enhanced radon concentrations in soil. Radon (222Rn and 220Rn) concentration measurements in soil gas (using ionization chamber AlphaGUARD PQ2000 PRO and diffusion chambers with CR-39 detectors), as well as radioactive natural isotopes of radium, thorium and potassium in soil samples (using gamma ray spectrometry with NaI(Tl) and HPGe detectors), were performed. Site selection was based on a geological map of Krakow. Geophysical methods (ground penetrating radar and shallow acoustic seismic) were applied to recognize the geological structure of the area and to locate the predicted courses of faults. Elevated levels of radon and thoron in soil gas were found in the study area when compared with those observed in an earlier survey covering Krakow agglomeration. For 222Rn, the arithmetic mean of registered concentration values was 39 kBq/m3 (median: 35.5 kBq/m3). For 220Rn, the arithmetic mean was 10.8 kBq/m3 and median 11.8 kBq/m3.
Correlation between radon concentration and geological structure of the Kraków area
Authors: K Kozak, J Swakoń, M Paszkowski, R Gradziński, J Łoskiewicz, M Janik, J Mazur, J Bogacz, T Horwacik, P Olko
Journal: Radioactivity in the Environment
Volume: 7
Issue:
Pages: 464-469
Year: 2005
Abstract: This chapter investigates the influence of the geological structure of bedrock on the concentration of radon in soil gas and in the buildings. The radon (222Rn and 220Rn) concentration in soil gas was measured using the Alpha GUARD PQ2000PRO ionization chamber and CR-39 detectors. In addition, natural radioactive isotopes (radium, thorium and potassium) in soil samples were determined using gamma spectrometry with NaI and HPGe detectors. The selection of measurement areas was based on the study of geological maps of Kraków. Geophysical methods (ground penetrating radar and shallow acoustic seismic) were applied to detail the geological structures. The chapter presents identification of the mechanisms that are responsible for higher radon concentrations and the determination of radon migration routes in shallow geological layers require further research in situ as well as a more complete investigation of the physical characteristics of the ground.
Radon in well waters in the Kraków area
Authors: Elzbieta Kochowska, Jadwiga Mazur, Krzysztof Kozak, Miroslaw Janik
Journal: Isotopes in Environmental and Health Studies
Volume: 40
Issue: 3
Pages: 207-212
Year: 2004
Abstract: The method and the results of radon concentration measurements in water samples are presented. Since May 2000, measurements of radon concentration in well waters in the Kraków area have been carried out – both in urban wells (depth above 50 meters) and in other private wells (depth of several meters). The ionisation chamber AlphaGUARD PQ 2000PRO along with the additional special equipment AquaKIT were used for determination of radon concentration in water samples. A total of 45 wells were examined for radon concentration in water—19 urban wells, 21 private ones (from Nowa Huta, Ojcowska, Wola Justowska area – parts of Kraków) and 5 mineral water sources. Wola Justowska is a region where tectonics faults occur and radon can easily migrate from deep basement structure. All the obtained values of radon concentration are below 12 Bq/l. These preliminary results do not show a direct correlation between geological structure and radon concentration in water samples. However, further investigation is needed and is planned to be undertaken.
Calibration of soil probe for in situ permeability measurement
Authors: M Janik, K Kozak
Journal: Prace Naukowe GIG. Górnictwo i Środowisko/Główny Instytut Górnictwa
Volume:
Issue: 1
Pages: 58-59
Year: 2004
Abstract: Soil permeability is one of the important physical soil parameters for modeling radon transport from soil to indoor. Permeability relates flow (v) through the soil pores to the pressure gradient (dp). For in situ permeability measurement we applied a soil probe that was designed and made at the INP, PAS. Because permeability depends on velocity we calibrated our probe in laboratory conditions. For calibration we applied semi-empirical formula for permeability, depending on porosity, particle-size and soil water saturation fraction. We used two types of sand, because it is almost isotropic and homogenous medium.
Radon chambers-technical design and some calibration problems
Authors: Krzysztof Kozak, Jadwiga Mazur, Mirosław Janik, Ryszard Haber
Journal: Prace Naukowe GIG. Górnictwo i Środowisko/Główny Instytut Górnictwa
Volume:
Issue: 1
Pages: 57-58
Year: 2004
Abstract: In the Natural Radioactivity Laboratory (at the H. Niewodniczański Institute of Nuclear Physics, PAS in Kraków) the special stand was designed and made for the calibration of radon detectors and for other research activities. The stand is equipped with two calibration chambers: IFJ-KR-200 (volume of 200 dm3) and IFJ-KR-600 (volume of 600 dm3), two certificated radon sources (226Ra activities: 21.6 and 52.3 kBq), a pump, a flow meter, a manometer and a control panel. The range of possible radon concentrations is from 45 Bq/m3 to 244 kBq/m3. The computer software has been elaborated for planning and controlling the calibration procedure.
Asymptotic solutions of neutron transport equation and the limits of correct use of diffusion approximation for rocks
Authors: D Dworak, J Łoskiewicz, M Janik
Journal: Applied Radiation and Isotopes
Volume: 54
Issue: 5
Pages: 845-848
Year: 2001
Abstract: The diffusion approximation solution for neutron transport has been used in well-logging geophysics for calculating tool responses in boreholes, sometimes with success. The problem of the dimension of different materials to which it can be applied with success is important for the borehole environment. The results obtained show that the diffusion approximation can be used for distances greater than a few millimetre in some rock types. For iron, barium, and other highly absorbing media the use of the diffusion approximation is inappropriate even for large distances.
The calibration of activated charcoal detectors in a small 222Rn exposure chamber
Authors: J Bogacz, J Mazur, J Swakoń, M Janik
Journal: Radiation Measurements
Volume: 33
Issue: 6
Pages: 873-878
Year: 2001
Abstract: Passive methods for radon measurements, especially those based on radon adsorption, require observation of proper calibration methods. The calibration method for diffusion-barrier charcoal detectors in a small radon chamber has been proposed. The theoretical dependence of radon concentration vs. time inside the chamber during the exposure of charcoal detectors has been obtained and verified experimentally. For this purpose, the chamber volume as well as diffusion and adsorption parameters of the detector were taken into consideration. For two types of detectors the conformity of calibration factors obtained in two ways: calculated from theoretical points and from experimental points was achieved. The proposed method makes it possible to calibrate different kinds of radon-adsorbing detectors (not only charcoal canisters) in small chambers without the necessity of using any reference, active device.
Pomiary stężenia radonu w powietrzu glebowym
Authors: J Swakon, M Paszkowski, T Horwacik, M Janik, D Mazur, J Loskiewicz, P Olko
Journal: Sesja Naukowa Radon w Środowisku, IFJ, Kraków
Volume:
Issue:
Pages:
Year: 2000
Abstract: No data
DOI: NULL
Measurements of radon concentration in soil gas by CR-39 detectors
Authors: D Mazur, M Janik, J Łoskiewicz, P Olko, J Swakoń
Journal: Radiation Measurements
Volume: 31
Issue: 1-6
Pages: 295-300
Year: 1999
Abstract: A miniature diffusion chamber with a 25 × 4 × 0.5 mm CR-39 track etch detector (Pershore Moulding Ltd.), mounted on the 1.1 m long pole has been developed for radon gas measurements at 1 meter depth in the soil. For chemically etched CR-39 (7h, 70°C NaOH) and automatic track analysis the lowest detection limit of the chamber was found to be 0.5 MBq h m−3 and the useful exposure range from 2 to 20 MBq h m−3. The typical exposure time in the soil is between 2 to 14 days. The chamber was tested against the active AlphaGUARD PQ-2000 (Genitron Instruments GmbH) probe. The test yielded consistent results for soils with typical values of permeability and which are not miniature with water. The pilot measurements of radon gas in soil conducted with the miniature diffusion chambers around 48 buildings in Kraków and Silesia regions yielded an average radon concentration of 13 kBq m−3. The chambers are to be applied to measure radon concentration in soil before constructing new houses in order to avoid high radon risk areas.