Pin-hole Dosimeters Research Articles

Indoor radon and thoron levels in some residences of Sri Renga Narayana Puram Village, Tirunelveli, India, using solid-state nuclear track detectors

The indoor radon and thoron measurements were carried out at Sri Renga Narayana Puram village, Tirunelveli district, Tamil Nadu, which is located nearer to the Nuclear Power Plant, Kudankulam. The survey was performed using a single-entry pin-hole dosimeter with a solid-state nuclear track detector for a period of 90 days. In the present study, the radon and thoron levels have been measured initially for 10 residences using LR-115 Type II films as a detector. The dose assessment due to radon and thoron is calculated. The effective dose of radon and thoron in the corresponding residences has been found to vary from 0.516 to 0.660 mSvy−1 and 0.010 to 0.144 mSvy−1. The total effective dose due to radon and thoron has been calculated which found to vary from 0.545 to 0.791 mSvy−1 with an average value of 0.655 mSvy−1.

Estimation of Radon/Thoron and their progeny concentration in some dwellings and exhalation rates from soils of Samana city, Patiala

The study of indoor pollutants and radioactive nuclides imposes importance on human health as we spend most of our time indoors. Out of all the natural radioactive elements, Radon-222 and Radon220 are present in large abundance indoors. Both are radioactive and decay to various short-lived progenies by emitting high-energy alpha particles, so inhalation of such gases can harm the human body in various ways. In the present report, the concentration of Rn-222 and Rn-220 and its progenies are estimated from some dwellings of Samana city of Patiala district, Punjab. Pin-hole dosimeters with DRPS and DTPS were employed in 15 houses in the study area to measure indoor Rn-222 and Rn-220 concentrations. The concentration of Rn-222 ranges between 401.96 Bq/m3 and 27.36 Bq/m3 with mean value of 138.82 Bq/m3, and the concentration of Rn-220 varies from 222.2 Bq/ m3 to 50 Bq/m3 with the mean weight of 131.12 Bq/m3. The average inhalation dose was also calculated from the results and was found to have an average value of 2.19 mSv per year. The average weight of radon concentration was below the ICRP recommendation of 200-300 Bq/m3 but the value is above these limits at some locations. Radon and thoron emission rates from soil samples near to the dwellings was also calculated.

Annual effective dose due to inhalation of indoor radionuclides and their progeny measured by track etched techniques using pinhole dosimeter and deposition-based progeny sensors

Annual effective dose due to inhalation of indoor radionuclides and their progeny measured by track etched techniques using pinhole dosimeter and deposition-based progeny sensors

Dosimetry of indoor alpha flux belonging to seasonal radon, thoron and their EECs.

Radon (222Rn) and thoron (220Rn) are ubiquitous radioactive noble gases present in the earth's crust. The source term for these gases includes soil and building materials as well. The radiological impact of radon/thoron gases and their decay products on human life is a matter of concern and has been given due attention in research and policy. The present study aims to measure and quantify residential radon/thoron gas and the decay product's concentration and to discuss the associated interpretations for Ludhiana district of Punjab, India. Passive measurement techniques employing a single-entry pinhole dosimeter for gases and direct progeny sensors for the decay product's concentration have been used in this work. The obtained data from these measurements have been analysed using appropriate statistical techniques. The variations have been linked with the changes in the ventilation conditions, building material, room type and altitude. A higher concentration of radon and thoron gas was observed in the winter season for the study region. It was estimated that the contribution of radon and thoron decay products towards the annual average inhalation dose is 75% and 25%, respectively.

Estimation of indoor 222 Rn and 220 Rn concentration and annual inhalation dose in the indoor environment around Kolar district of Karnataka state, India

The indoor 222Rn and 220Rn were measured by using deposition progeny sensors and single-entry pinhole dosimeter around Kolar Gold Fields of Karnataka state, India. The thirty different places were identified and fixed the dosimetry cups for the determination. The 222Rn and 220Rn concentrations of indoor environment range from 26.2 ± 1.3 to 138.4 ± 1.6 and 21.2 ± 0.8 to 133.3 ± 1.5 Bq/m3 with a mean value of 68.8 ± 1.6 and 61.8 ± 1.5 Bq/m3, respectively. The equivalent concentrations of 222Rn and 220Rn values vary from 0.9 ± 0.4 to 7.6 ± 1.1 and 6.8 ± 0.8 to 19.8 ± 1.8 Bq/m3 with a standard value of 4.3 ± 0.8 and 14.2 ± 1.3 Bq/m3, respectively. The values between the equilibrium factor between 222Rn, 220Rn, and their daughter were also calculated and found to be 0.23 and 0.07, respectively. The average annual intake of 222Rn, 220Rn, and their daughters' products is 2.28 mSv/y1, slightly below the global average of 2.4 mSv/y1from all components. The data obtained compare average values in the world.

Inhalation dose due to residential radon and thoron exposure in rural areas: a case study at Erravalli and Narasannapet model villages of Telangana state, India.

Exposure to indoor radon has been identified as a cause of lung cancer. The corresponding inhalation radiation dose received is an important parameter in estimating the risk of cancer due to the inhalation of radon. The present investigation is aimed at the estimation of the radiation dose due to radon, its isotopes, and progeny to the public residing in dwellings constructed in model villages of Telangana state, India. The indoor activity concentrations of radon and thoron were measured using pin-hole dosimeters. The measured activities along with appropriate dose conversion and occupancy factors were used in the estimation of the dose received by the dwellers. The doses estimated were compared with those to inhabitants of control dwellings. The estimated doses received by the public due to radon were found to be 1.54 ± 0.60mSv and 1.51 ± 1.20mSv, in the investigated model houses and in the control dwellings, respectively. Correspondingly, radiation doses due to thoron were found to be 1.08 ± 0.81mSv and 1.44 ± 1.04mSv, respectively. It is concluded that the model dwellings pose no extra radiation burden to the public.

Dose distribution to individual tissues and organs due to exposure of alpha energies from radon and thoron to local population of Hanumangarh, Rajasthan, India

The purpose of the present study is to assess dose received by individual tissues or organs of human beings from the exposure of indoor radon (Rn-222), thoron (Rn-220) and their progeny concentrations using single entry pinhole dosimeters and deposition based progeny sensors (DRPS/DTPS). The deployment of dosimeters were carried out in 75 dwellings across Hanumangarh district of Rajasthan, India. Annual and seasonal activity concentrations were monitored based on which dose distribution to various tissues and organs were assessed. The estimated average annual effective dose of the study area is 0.8 mSvy−1, which is lower than the ICRP recommended limit of 4 mSvy−1 (at work place) and 14 mSvy−1 (for residential buildings) (International Commission on Radiological Protection (ICRP) in Radiological protection against radon exposure, ICRP, Stockholm, 2018). Consequently, indoor radon may pose no health risk to the local population of the studied area.

Studies on radon and thoron levels in few dwellings of Kabini River Basin, Karnataka State, India

Measurement of indoor radon, thoron and their equilibrium equivalent concentrations in different dwellings around Kabini river basin, Karnataka State, India was carried out using SSNTD based pin-hole dosimeters during 2017–2018. Indoor concentrations of radon and thoron are varied from 18.9 to 156.8 Bq m− 3 and 13.1 to 110.0 Bq m− 3, respectively. The present study reveals that the annual effective dose received by the people of the study area is lesser than the recommended level 3–10 mSv y− 1 of the International Commission of Radiological Protection and is safe from the exposure of radon, thoron and their progenies.

STUDY OF INDOOR RADON, THORON AND THEIR PROGENY IN SOUTH WEST KHASI HILLS DISTRICT OF MEGHALAYA, INDIA.

A survey of indoor radon/thoron and their progeny concentrations was carried out in dwellings in the South West Khasi Hills district of Meghalaya, India. The survey was carried out using solid-state nuclear track detectors based on single-entry pinhole dosimeter and direct radon/thoron progeny sensors. The results are subjected to statistical analysis and discussed in the manuscript. The mean value of annual effective dose of the study region is estimated at 1.8mSv.y -1. Seasonal variability and role of different indoor parameters are also discussed.

Comparison of results from indoor radon measurements using active and passive methods with those from mathematical modeling.

Computational fluid dynamics (CFD) has been used to simulate the distribution of indoor radon concentration in a naturally ventilated room. Finite volume method was employed in CFD code for the simulation of indoor radon. The simulation results were validated at 34 points in a matrix of two horizontal planes (y = 1.3m and y = 2.1m) using passive pinhole dosimeters and at six points using an active scintillation radon monitor. The CFD results were found to exhibit an excellent correlation with the measured values. It is concluded that CFD analysis is a powerful tool to visualize indoor radon distribution.

Risk assessment due to inhalation of radon in Coorg district, Karnataka

The paper deals with study of seasonal variation of outdoor and indoor radon in Somwarpet taluk, Coorg district using pin-hole dosimeter cups and LR-115(type II) films. The LR-115 films, placed in dosimeter cups with pin-holes, were exposed to radon in different seasons of the year. The annual inhalation dose due to outdoor and indoor radon ranges from 0.036 to 0.068 mSv year−1 and 0.53 to 0.75 mSv year−1 respectively. The radon levels are low, due to blocking of radon atoms in porespaces of porous soil, due to rainfall in all seasons.

Indoor radon ( 222 Rn) and thoron ( 220 Rn) measurements and assessment of human risk in the dwellings of Tiruchirappalli city (Tamil Nadu, India)

Indoor radon and thoron measurements were carried out in 92 dwellings of Tiruchirappalli city employing single entry pin-hole dosimeter with a solid state nuclear track detector for a period of one year covering all four seasons. The results indicated that the indoor radon and thoron concentrations varied dynamically throughout the year. The maximum mean indoor radon concentration (42.1 ± 20 Bq m−3) and thoron concentration (98.2 ± 23 Bq m−3) were registered during monsoon season and minimum mean radon concentration (26.1 ± 14.5 Bq m−3) and thoron concentration (36.6 ± 18.8 Bq m−3) during pre monsoon season. Indoor radon and thoron concentrations are directly related to the types of building materials, ventilation rate and atmospheric temperature. The mean indoor radon concentration was 33.2 Bq m−3 which was within the safe limit of 300 Bq m−3 as set by WHO. Hence this study concluded that the indoor radon and thoron concentrations in the studied region did not pose any radiological hazard to dwellers.

Radiological variation of indoor radon and thoron levels by pinhole dosimeter in different seasons

The annual variation in radon and thoron concentrations in different seasons has been revealed for 40 different locations of Jodhpur, Nagaur, Bikaner and Jhunjhunu districts of Northern Rajasthan by using pinhole dosimeter, and the results have been compared with ventilation conditions and building materials. The indoor radon concentration was observed to vary from 109 ± 17 to 334 ± 13 Bq m−3, 63 ± 17 to 255 ± 21 Bq m−3, 45 ± 11 to 128 ± 19 Bq m−3 and 74 ± 9 to 300 ± 21 Bq m−3 and thoron concentration varies from 26 ± 15 to 418 ± 21 Bq m−3, 3 ± 2 to 134 ± 33 Bq m−3, 12 ± 6 to 140 ± 19 Bq m−3 and 6 ± 4 to 408 ± 29 Bq m−3 for winter, spring, summer and autumn seasons, respectively. In winter season, indoor radon concentration of about 50% dwellings was observed to be within or higher than the action level as recommended by International Commission of Radiation Protection. However, in summer the action level is lower than the action limit. The exposure of human beings to indoor radon and thoron and the associated risk has also been examined. The total annual mean effective dose due to indoor radon and thoron in Northern Rajasthan are less than or close to the action level 3–10 mSv y−1 as recommended by International Commission of Radiation Protection.

Measurment of radon, thoron and their progeny in indoor environment of Mohali, Punjab, Northern India, using pinhole dosimeters

The health hazards of radon and its decay products above certain levels are well known. However, for any preventive measures to be taken, we have to be aware of radon levels of that particular area. Measurement of radon and its decay products in indoor environments is an important aspect of assessing indoor air quality and health conditions associated with it. Keeping this in mind, measurements of radon, thoron and their progeny concentrations were carried out in Mohali, Northern India, using pinhole-based twin cup dosimeters. Radon exhalation rates of soil samples in the dwellings/areas were measured via an active technique of a continuous radon monitor. The indoor radon concentration in Mohali varied from 15.03 ? 0.61 Bq/m3 to 39.21 ? 1.46 Bq/m3 with an average of 26.95 Bq/m3 ,while thoron concentration in the same dwellings varied from 9.62 ? 0.54 Bq/m3 to 52.84 ? 2.77 Bq/m3 with an average of 31.09 Bq/m3. Radon progeny levels in dwellings under study varied from 1.63 to 4.24 mWL, with an average of 2.94 mWL, while thoron progeny levels varied from 0.26 to 1.43 mWL , with an average of 0.84 mWL. The annual dose received by the inhabitants of dwellings under study varied from 0.78 to 2.36 mSv, with an average of 1.61 mSv. The in situ gamma dose rate varied from 0.12 to 0.32 mSv/h.

Variability of radon and thoron equilibrium factors in indoor environment of Garhwal Himalaya

The measurements of radon, thoron and their progeny concentrations have been carried out in the dwellings of Uttarkashi and Tehri districts of Garhwal Himalaya, India using LR-115 detector based pin-hole dosimeter and DRPS/DTPS techniques. The equilibrium factors for radon, thoron and their progeny were calculated by using the values measured with these techniques. The average values of equilibrium factor between radon and its progeny have been found to be 0.44, 0.39, 0.39 and 0.28 for rainy, autumn, winter and summer seasons, respectively. For thoron and its progeny, the average values of equilibrium factor have been found to be 0.04, 0.04, 0.04 and 0.03 for rainy, autumn, winter and summer seasons, respectively. The equilibrium factor between radon and its progeny has been found to be dependent on the seasonal changes. However, the equilibrium factor for thoron and progeny has been found to be same for rainy, autumn and winter seasons but slightly different for summer season. The annual average equilibrium factors for radon and thoron have been found to vary from 0.23 to 0.80 with an average of 0.42 and from 0.01 to 0.29 with an average of 0.07, respectively. The detailed discussion of the measurement techniques and the explanation for the results obtained is given in the paper.

Monitoring of radon, thoron, their progeny concentrations in dwellings, and radon exhalation rates of soil/sand of Rupnagar district, Punjab, India

Radon and its progeny are major contributors in the radiation dose received by general population of the world. Keeping this in mind, the environmental monitoring of radon–thoron and their progeny in dwellings of district Rupnagar, Punjab, India has been carried out. Both radon–thoron twin dosimeter cups and the newly developed pin-hole dosimeters cups by BARC, India were used for the study. The study reveals good agreement between the values measured by the two types of dosimeters. Radon exhalation rate from soil samples of these dwellings/areas have been carried out using “Canister Technique.” The radon exhalation rates of some soil samples of these dwellings/areas were also measured by an active technique using a continuous radon monitor. Both the active and passive techniques show the exhalation rate values to be lower than the worldwide average. The study of the exhalation rate of the soil samples of Nangal and Anandpur Sahib of the district Rupnagar and the sand samples available from the study area has also been carried out for the possible use as construction material. The in situ gamma dose varied from 0.13 to 0.33 µSv/h.

Active-passive measurements and CFD based modelling for indoor radon dispersion study

Computational fluid dynamics (CFD) play a significant role in indoor pollutant dispersion study. Radon is an indoor pollutant which is radioactive and inert gas in nature. The concentration level and spatial distribution of radon may be affected by the dwelling's ventilation conditions. Present work focus at the study of indoor radon gas distribution via measurement and CFD modeling in naturally ventilated living room. The need of the study is the prediction of activity level and to study the effect of natural ventilation on indoor radon. Two measurement techniques (Passive measurement using pin-hole dosimeters and active measurement using continuous radon monitor (SRM)) were used for the validation purpose of CFD results. The CFD simulation results were compared with the measurement results at 15 points, 3 XY planes at different heights along with the volumetric average concentration. The simulation results found to be comparable with the measurement results. The future scope of these CFD codes is to study the effect of varying inflow rate of air on the radon concentration level and dispersion pattern.

Measurements and CFD modeling of indoor thoron distribution

Abstract Few studies have been undertaken to measure indoor thoron concentration in Indian dwellings. The distribution pattern of thoron inside room conditions is complex due to short half-life. The internal radiation exposure due to inhalation of indoor thoron and decay products can be quite large near to the wall. In this work, Computational Fluid Dynamics (CFD) technique was utilized for prediction of indoor thoron concentration and distribution pattern. Thoron flux was measured experimentally to be used as input and CFD runs were performed for closed and open room conditions. Thoron concentration inside the room was also experimentally measured using Scintillation Thoron Monitor, STM (active) and pin-hole dosimeters (passive). For open room conditions, thoron concentration was found to be smaller and relatively homogenous compared to closed room conditions. CFD predictions were found to be reasonably matching with active and passive results. A separate profile experiment increased confidence towards validation of CFD for indoor thoron distribution (prediction) applications. CFD can be used as a tool to predict thoron concentration and its distribution in indoor conditions.

Study of radon, thoron and their progeny levels in indoor environment of Firozabad city in U.P., India

Twin cup pin-hole dosimeters having LR-115 as the detector were used to measure the concentration of radon and thoron in the dwellings of Firozabad city of Uttar Pradesh State in India. The mean values of radon, thoron, radon progeny and thoron progeny concentrations were found to be 37.4 Bqm−3, 13.7 Bqm−3, 4.0 and 1.5 mWL respectively. The average value of annual effective dose equivalent to the inhabitants of Firozabad city was found to be 1.1 mSv and is below the action level as recommended by the ICRP.

Study of indoor radon distribution using measurements and CFD modeling

Measurement and/or prediction of indoor radon (222Rn) concentration are important due to the impact of radon on indoor air quality and consequent inhalation hazard. In recent times, computational fluid dynamics (CFD) based modeling has become the cost effective replacement of experimental methods for the prediction and visualization of indoor pollutant distribution. The aim of this study is to implement CFD based modeling for studying indoor radon gas distribution. This study focuses on comparison of experimentally measured and CFD modeling predicted spatial distribution of radon concentration for a model test room. The key inputs for simulation viz. radon exhalation rate and ventilation rate were measured as a part of this study. Validation experiments were performed by measuring radon concentration at different locations of test room using active (continuous radon monitor) and passive (pin-hole dosimeters) techniques. Modeling predictions have been found to be reasonably matching with the measurement results. The validated model can be used to understand and study factors affecting indoor radon distribution for more realistic indoor environment.