Prediction of indoor radon/thoron concentration in a model room from exhalation rates of building materials for different ventilation rates

NASA Astrophysics Data System (ADS)

Kumar, Manish; Sharma, Navjeet; Sarin, Amit

2018-05-01

Studies have confirmed that elevated levels of radon/thoron in the human-environments can substantially increase the risk of lung cancer in general population. The building materials are the second largest contributors to indoor radon/thoron after soil and bedrock beneath dwellings. In present investigation, the exhalation rates of radon/thoron from different building materials samples have been analysed using active technique. Radon/thoron concentrations in a model room have been predicted based on the exhalation rates from walls, floor and roof. The indoor concentrations show significant variations depending upon the ventilation rate and type of building materials used.

Seasonal variability of equilibrium factor and unattached fractions of radon and thoron in different regions of Punjab, India.

PubMed

Saini, Komal; Singh, Parminder; Singh, Prabhjot; Bajwa, B S; Sahoo, B K

2017-02-01

A survey was conducted to estimate equilibrium factor and unattached fractions of radon and thoron in different regions of Punjab state, India. Pin hole based twin cup dosimeters and direct progeny sensor techniques have been utilized for estimation of concentration level of radon, thoron and their progenies. Equilibrium factor calculated from radon, thoron and their progenies concentration has been found to vary from 0.15 to 0.80 and 0.008 to 0.101 with an average value of 0.44 and 0.036 for radon and thoron respectively. Equilibrium factor for radon has found to be highest in winter season and lowest in summer season whereas for thoron highest value is observed in winter and rainy season and lowest in summer. Unattached fractions of radon and thoron have been found to vary from 0.022 to 0.205 and 0.013 to 0.212 with an average value of 0.099 and 0.071 respectively. Unattached fractions have found to be highest in winter season and lowest in rainy and summer season. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of soil environmental parameters on thoron exhalation rate.

PubMed

Hosoda, M; Tokonami, S; Sorimachi, A; Ishikawa, T; Sahoo, S K; Furukawa, M; Shiroma, Y; Yasuoka, Y; Janik, M; Kavasi, N; Uchida, S; Shimo, M

2010-10-01

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.

STUDY OF RADIATION EXPOSURE DUE TO RADON, THORON AND THEIR PROGENY IN THE INDOOR ENVIRONMENT OF RAJPUR REGION OF UTTARAKHAND HIMALAYA.

PubMed

Kandari, Tushar; Aswal, Sunita; Prasad, Mukesh; Pant, Preeti; Bourai, A A; Ramola, R C

2016-10-01

In the present study, the measurements of indoor radon, thoron and their progeny concentrations have been carried out in the Rajpur region of Uttarakhand, Himalaya, India by using LR-115 solid-state nuclear track detector-based time-integrated techniques. The gas concentrations have been measured by single-entry pin-hole dosemeter technique, while for the progeny concentrations, deposition-based Direct Thoron and Radon Progeny Sensor technique has been used. The radiation doses due to the inhalation of radon, thoron and progeny have also been determined by using obtained concentrations of radon, thoron and their progeny in the study area. The average radon concentration varies from 75 to 123 Bq m -3 with an overall average of 89 Bq m -3 The average thoron concentration varies from 29 to 55 Bq m -3 with an overall average of 38 Bq m -3 The total annual effective dose received due to radon, thoron and their progeny varies from 2.4 to 4.1 mSv y -1 with an average of 2.9 mSv y -1 While the average equilibrium factor for radon and its progeny was found to be 0.39, for thoron and its progeny, it was 0.06. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Mitigation of radon and thoron decay products by filtration.

PubMed

Wang, Jin; Meisenberg, Oliver; Chen, Yongheng; Karg, Erwin; Tschiersch, Jochen

2011-09-01

Inhalation of indoor radon ((222)Rn) and thoron ((220)Rn) decay products is the most important source of exposure to ionizing radiation for the human respiratory tract. Decreasing ventilation rates due to energy saving reasons in new buildings suggest additional active mitigation techniques to reduce the exposure in homes with high radon and thoron concentrations but poor ventilation. Filtration techniques with HEPA filters and simple surgical mask material have been tested for their potential to reduce the indoor exposure in terms of the total effective dose for mixed radon and thoron indoor atmospheres. The tests were performed inside an experimental room providing stable conditions. Filtration (at filtration rates of 0.2 h(-1) and larger) removes attached radon and thoron decay products effectively but indoor aerosol as well. Therefore the concentration of unattached decay products (which have a higher dose coefficient) may increase. The decrease of the attached decay product concentrations could be theoretically described by a slowly decreasing exponential process. For attached radon decay products, it exhibited a faster but weaker removal process compared to attached thoron decay products (-70% for attached radon decay products and -80% for attached thoron decay products at a filtration rate of 0.5 h(-1) with an HEPA filter). The concentration of unattached thoron decay products increased distinctly during the filtration process (+300%) while that of unattached radon decay products rose only slightly though at a much higher level (+17%). In the theoretical description these observed differences could be attributed to the different half-lives of the nuclides. Considering both effects, reduced attached and increased unattached decay product concentrations, filtration could significantly decrease the total effective dose from thoron whereas the overall effect on radon dose is small. A permanent filtration is recommended because of the slow decrease of the thoron decay product concentrations. Copyright © 2011 Elsevier B.V. All rights reserved.

Long-term measurements of radon, thoron and their airborne progeny in 25 schools in Republic of Srpska.

PubMed

Ćurguz, Z; Stojanovska, Z; Žunić, Z S; Kolarž, P; Ischikawa, T; Omori, Y; Mishra, R; Sapra, B K; Vaupotič, J; Ujić, P; Bossew, P

2015-10-01

This article reports results of the first investigations on indoor radon, thoron and their decay products concentration in 25 primary schools of Banja Luka, capital city of Republic Srpska. The measurements have been carried out in the period from May 2011 to April 2012 using 3 types of commercially available nuclear track detectors, named: long-term radon monitor (GAMMA 1)- for radon concentration measurements (C(Rn)); radon-thoron discriminative monitor (RADUET) for thoron concentration measurements (C(Tn)); while equilibrium equivalent radon concentration (EERC) and equilibrium equivalent thoron concentrations (EETC) measured by Direct Radon Progeny Sensors/Direct Thoron Progeny Sensors (DRPS/DTPS) were exposed in the period November 2011 to April 2012. In each school the detectors were deployed at 10 cm distance from the wall. The obtained geometric mean concentrations were C(Rn) = 99 Bq m(-3) and C(Tn) = 51 Bq m(-3) for radon and thoron gases respectively. Those for equilibrium equivalent radon concentration (EERC) and equilibrium equivalent thoron concentrations (EETC) were 11.2 Bq m(-3) and 0.4 Bq m(-3), respectively. The correlation analyses showed weak relation only between C(Rn) and C(Tn) as well as between C(Tn) and EETC. The influence of the school geographical locations and factors linked to buildings characteristic in relation to measured concentrations were tested. The geographical location and floor level significantly influence C(Rn) while C(Tn) depend only from building materials (ANOVA, p ≤ 0.05). The obtained geometric mean values of the equilibrium factors were 0.123 for radon and 0.008 for thoron. Copyright © 2015 Elsevier Ltd. All rights reserved.

Radon and thoron inhalation doses in dwellings with earthen architecture: Comparison of measurement methods.

PubMed

Meisenberg, Oliver; Mishra, Rosaline; Joshi, Manish; Gierl, Stefanie; Rout, Rajeswari; Guo, Lu; Agarwal, Tarun; Kanse, Sandeep; Irlinger, Josef; Sapra, Balvinder K; Tschiersch, Jochen

2017-02-01

The radioactive noble gas radon ( 222 Rn) and its decay products have been considered a health risk in the indoor environment for many years because of their contribution to the radiation dose of the lungs. The radioisotope thoron ( 220 Rn) and its decay products came into focus of being a health risk only recently. The reason for this is its short half-life, so only building material can become a significant source for indoor thoron. In this study, dwellings with earthen architecture were investigated with different independent measurement techniques in order to determine appropriate methods for reliable dose assessment of the dwellers. While for radon dose assessment, radon gas measurement and the assumption of a common indoor equilibrium factor often are sufficient, thoron gas has proven to be an unreliable surrogate for a direct measurement of thoron decay products. Active/time-resolved but also passive/integrating measurements of the total concentration of thoron decay products demonstrated being precise and efficient methods for determining the exposure and inhalation dose from thoron and its decay products. Exhalation rate measurements are a useful method for a rough dose estimate only if the exhalation rate is homogeneous throughout the house. Before the construction of a building in-vitro exhalation rate measurements on the building material can yield information about the exposure that is to be expected. Determining the unattached fraction of radon decay products and even more of thoron decay products leads to only a slightly better precision; this confirms the relative unimportance of the unattached thoron decay products due to their low concentration. The results of this study thereby give advice on the proper measurement method in similar exposure situations. Copyright © 2017 Elsevier B.V. All rights reserved.

MEASUREMENT OF RADON, THORON AND THEIR PROGENY CONCENTRATIONS IN THE DWELLINGS OF PAURI GARHWAL, UTTARAKHAND, INDIA.

PubMed

Joshi, Veena; Dutt, Sanjay; Yadav, Manjulata; Mishra, Rosaline; Ramola, R C

2016-10-01

It is well known that inhalation of radon, thoron and their progeny contributes more than 50 % of natural background radiation dose to human being. The time-integrated passive measurements of radon, thoron and their progeny concentrations were carried out in the dwellings of Pauri Garhwal, Uttarakhand, India. The measurements of radon and thoron concentrations were performed by LR-115 detector-based single-entry pin-hole dosemeter, while for the measurement of progeny concentrations, LR-115 deposition-based direct radon and thoron progeny sensors technique was used. The experimental techniques and results obtained are discussed in detail. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Thoron in the environment and its related issues

NASA Astrophysics Data System (ADS)

Tokonami, Shinji

2009-06-01

Since radon is internationally noted as the second cause of lung cancer, many countries are trying about to solve the problem worldwide. In addition, a new evidence of lung cancer risk has been recently found out with a low level below 200 Bq m-3. Thus the action level will have to be set lower than before. Importance of radon exposure has been further recognized and accurate radon concentrations will be required. Recently thoron has also been recognized from the viewpoint of accurate radon measurements. The present paper describes specification of the NIRS radon and thoron chambers, passive measurement technique of radon and thoron and thoron interference on radon measurements from both experimental studies and field experiences on epidemiological study area.

International intercomparison of measuring instruments for radon/thoron gas and radon short-lived daughter products in the NRPI Prague.

PubMed

Jílek, K; Hýža, M; Kotík, L; Thomas, J; Tomášek, L

2014-07-01

During the 7th European Conference on Protection Against Radon at Home and at Work held in the autumn of 2013 in Prague, the second intercomparison of measuring instruments for radon and its short-lived decay products and the first intercomparison of radon/thoron gas discriminative passive detectors in mix field of radon/thoron were organised by and held at the Natural Radiation Division of the National Radiation Protection Institute (NRPI) in Prague. In total, 14 laboratories from 11 different countries took part in the 2013 NRPI intercomparison. They submitted both continuous monitors for the measurement of radon gas and equivalent equilibrium radon concentration in a big NRPI chamber (48 m3) and sets of passive detectors including radon/thoron discriminative for the measurement of radon gas in the big chamber and thoron gas in a small thoron chamber (150 dm3). © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Calibration of CR-39-based thoron progeny device.

PubMed

Fábián, F; Csordás, A; Shahrokhi, A; Somlai, J; Kovács, T

2014-07-01

Radon isotopes and their progenies have proven significant role in respiratory tumour formation. In most cases, the radiological effect of one of the radon isotopes (thoron) and its progenies has been neglected together with its measurement technique; however, latest surveys proved that thoron's existence is expectable in flats and in workplace in Europe. Detectors based on different track detector measurement technologies have recently spread for measuring thoron progenies; however, the calibration is not yet completely elaborated. This study deals with the calibration of the track detector measurement method suitable for measuring thoron progenies using different devices with measurement techniques capable of measuring several progenies (Pylon AB5 and WLx, Sarad EQF 3220). The calibration factor values related to the thoron progeny monitors, the measurement uncertainty, reproducibility and other parameters were found using the calibration chamber. In the future, the effects of the different parameters (aerosol distribution, etc.) will be determined. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Soil gas radon-thoron monitoring in Dharamsala area of north-west Himalayas, India using solid state nuclear track detectors

NASA Astrophysics Data System (ADS)

Kumar, Gulshan; Kumar, Arvind; Walia, Vivek; Kumar, Jitender; Gupta, Vikash; Yang, Tsanyao Frank; Singh, Surinder; Bajwa, Bikramjit Singh

2013-10-01

The study described here is based on the measurements of soil gas radon-thoron concentrations performed at Dharamsala region of north-west (NW) Himalayas, India. The study area is tectonically and environmentally significant and shows the features of ductile shear zone due to the presence of distinct thrust planes. Solid state nuclear track detectors (LR-115 films) have been used for the soil gas radon-thoron monitoring. Twenty five radon-thoron discriminators with LR-115 films were installed in the borehole of about 50 cm in the study areas. The recorded radon concentration varies from 1593 to 13570 Bq/m3 with an average value of 5292 Bq/m3. The recorded thoron concentration varies from 223 to 2920 Bq/m3 with an average value of 901 Bq/m3. The anomalous value of radon-thoron has been observed near to the faults like main boundary thrust (MBT and MBT2) as well as neotectonic lineaments in the region.

The Influence of Internal Wall and Floor Covering Materials and Ventilation Type on Indoor Radon and Thoron Levels in Hospitals of Kermanshah, Iran.

PubMed

Pirsaheb, Meghdad; Najafi, Farid; Haghparast, Abbas; Hemati, Lida; Sharafi, Kiomars; Kurd, Nematullah

2016-10-01

Building materials and the ventilation rate of a building are two main factors influencing indoor radon and thoron levels (two radioactive gases which have the most important role in human natural radiation exposure within dwellings). This analytical descriptive study was intended to determine the relationship between indoor radon and thoron concentrations and the building materials used in interior surfaces, as well as between those concentrations and the type of ventilation system (natural or artificial). 102 measurements of radon and thoron levels were taken from different parts of three hospital buildings in the city of Kermanshah in the west of Iran, using an RTM-1688-2 radon meter. Information on the type of building material and ventilation system in the measurement location was collected and then analyzed using Stata 8 software and multivariate linear regression. In terms of radon and thoron emissions, travertine and plaster were found to be the most appropriate and inappropriate covering for walls, respectively. Furthermore, granite and travertine were discovered to be inappropriate materials for flooring, while plastic floor covering was found suitable. Natural ventilation performed better for radon, while artificial ventilation worked better for thoron. Internal building materials and ventilation type affect indoor radon and thoron concentrations. Therefore, the use of proper materials and adequate ventilation can reduce the potential human exposure to radon and thoron. This is of utmost importance, particularly in buildings with a high density of residents, including hospitals.

The Influence of Internal Wall and Floor Covering Materials and Ventilation Type on Indoor Radon and Thoron Levels in Hospitals of Kermanshah, Iran

PubMed Central

Pirsaheb, Meghdad; Najafi, Farid; Haghparast, Abbas; Hemati, Lida; Sharafi, Kiomars; Kurd, Nematullah

2016-01-01

Background Building materials and the ventilation rate of a building are two main factors influencing indoor radon and thoron levels (two radioactive gases which have the most important role in human natural radiation exposure within dwellings). Objectives This analytical descriptive study was intended to determine the relationship between indoor radon and thoron concentrations and the building materials used in interior surfaces, as well as between those concentrations and the type of ventilation system (natural or artificial). Materials and Methods 102 measurements of radon and thoron levels were taken from different parts of three hospital buildings in the city of Kermanshah in the west of Iran, using an RTM-1688-2 radon meter. Information on the type of building material and ventilation system in the measurement location was collected and then analyzed using Stata 8 software and multivariate linear regression. Results In terms of radon and thoron emissions, travertine and plaster were found to be the most appropriate and inappropriate covering for walls, respectively. Furthermore, granite and travertine were discovered to be inappropriate materials for flooring, while plastic floor covering was found suitable. Natural ventilation performed better for radon, while artificial ventilation worked better for thoron. Conclusions Internal building materials and ventilation type affect indoor radon and thoron concentrations. Therefore, the use of proper materials and adequate ventilation can reduce the potential human exposure to radon and thoron. This is of utmost importance, particularly in buildings with a high density of residents, including hospitals. PMID:28180013

Thoron detection with an active Radon exposure meter—First results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Irlinger, J., E-mail: josef.irlinger@helmholtz-muenchen.de; Wielunski, M.; Rühm, W.

For state-of-the-art discrimination of Radon and Thoron several measurement techniques can be used, such as active sampling, electrostatic collection, delayed coincidence method, and alpha-particle-spectroscopy. However, most of the devices available are bulky and show high power consumption, rendering them unfeasible for personal exposition monitoring. Based on a Radon exposure meter previously realized at the Helmholtz Center Munich (HMGU), a new electronic prototype for Radon/Thoron monitoring is currently being developed, which features small size and weight. Operating with pin-diode detectors, the low-power passive-sampling device can be used for continuous concentration measurements, employing alpha-particle-spectroscopy and coincidence event registration to distinguish decays originatingmore » either from Radon or Thoron isotopes and their decay products. In open geometry, preliminary calibration measurements suggest that one count per hour is produced by a 11 Bq m{sup −3} Radon atmosphere or by a 15 Bq m{sup −3} Thoron atmosphere. Future efforts will concentrate on measurements in mixed Radon/Thoron atmospheres.« less

Indoor radon and thoron concentrations in some towns of central and South Serbia.

PubMed

Vuckovic, Biljana; Gulan, Ljiljana; Milenkovic, Biljana; Stajic, Jelena M; Milic, Gordana

2016-12-01

This study presents the results of indoor radon and thoron activity concentrations of some municipalities in central and south part of Serbia: Krusevac, Brus, Blace and Kursumlija. Measurements were carried out in 60 dwellings during the winter season. Passive discriminative radon-thoron detectors known as UFO detectors were used. The mean values of indoor radon and thoron concentrations were 82 Bq m -3 and 42 Bq m -3 , respectively. Population-weighted mean values were 76 Bq m -3 and 40 Bq m -3 , respectively. 26.7% of dwellings had radon concentration higher than 100 Bq m -3 (one location had even more than 300 Bq m -3 ). There are no statistically significant correlations of indoor radon and thoron concentrations neither with the period of house construction, nor with the existence of a basement. The results of this study represent the first step of investigating radon and thoron levels in these parts of Serbia and therefore could be the basis for creating a radon map. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measurement of radon/thoron exhalation rates and gamma-ray dose rate in granite areas in Japan.

PubMed

Prasad, G; Ishikawa, T; Hosoda, M; Sahoo, S K; Kavasi, N; Sorimachi, A; Tokonami, S; Uchida, S

2012-11-01

Radon and thoron exhalation rates and gamma-ray dose rate in different places in Hiroshima Prefecture were measured. Exhalation rates were measured using an accumulation chamber method. The radon exhalation rate was found to vary from 3 to 37 mBq m(-2) s(-1), while the thoron exhalation rate ranged from 40 to 3330 mBq m(-2) s(-1). The highest radon exhalation rate (37 mBq m(-2) s(-1)) and gamma-ray dose rate (92 nGy h(-1)) were found in the same city (Kure City). In Kure City, indoor radon and thoron concentrations were previously measured at nine selected houses using a radon-thoron discriminative detector (Raduet). The indoor radon concentrations varied from 16 to 78 Bq m(-3), which was higher than the average value in Japan (15.5 Bq m(-3)). The indoor thoron concentration ranged from ND (not detected: below a detection limit of approximately 10 Bq m(-3)) to 314 Bq m(-3). The results suggest that radon exhalation rate from the ground is an influential factor for indoor radon concentration.

Thoron-tartaric acid systems for spectrophotometric determination of thorium

USGS Publications Warehouse

Grimaldi, F.S.; Fletcher, M.H.

1956-01-01

Thoron is commonly used for the spectrophotometric determination of thorium. An undesirable feature of its use is its high sensitivity to zirconium. This study describes the use of tartaric acid as a masking reagent for zirconium. Three tartaric acid-thoron systems, developed for the determination of thorium, differ with respect to the concentrations of thoron and tartaric acid. Mesotartaric acid, used in one of the systems, is most effective in masking zirconium. The behavior of rarer elements, usually associated with thorium ores, is determined in two systems, and a dilution method is described for the direct determination of thorium in monazite concentrates.

Comparison study and thoron interference test of different radon monitors.

PubMed

Sumesh, C G; Kumar, A Vinod; Tripathi, R M; Puranik, V D

2013-03-01

A comparison study and thoron interference test for different continuous radon monitors were carried out. The comparison study includes three passive diffusion monitors [one pulse ionisation chamber based-Alpha Guard and two silicon semi-conductor based-Radon Scout Plus (RSP)] and one silicon semi-conductor-based active radon thoron discriminating monitor--RAD 7. Radon emanation standard, supplied by National Institute of Science and Technology, has been utilised for the comparison study to qualify the calibration of the continuous radon monitors. All the instruments showed good agreement with the estimated radon concentration using (226)Ra/(222)Rn emanation standard. It was found that the active radon monitoring system is having a higher initial response towards the transient radon concentration than the passive radon monitors studied. The instruments measuring radon concentration without energy discrimination are likely to have some sensitivity towards the thoron concentration. Thus, thoron interference study was carried out in the above monitors. Nine percent interference in measured radon concentration in the Alpha Guard monitor and 4 % interference in the semi-conductor-based RSP monitors was observed. Study indicates that the interference of thoron in radon monitors depends on the area of diffusion of gas, volume of detection and sensitivity factor.

An unattended device for high-voltage sampling and passive measurement of thoron decay products.

PubMed

Gierl, Stefanie; Meisenberg, Oliver; Haninger, Thomas; Wielunski, Marek; Tschiersch, Jochen

2014-02-01

An integrating measurement device for the concentration of airborne thoron decay products was designed and calibrated. It is suitable for unattended use over up to several months also in inhabited dwellings. The device consists of a hemispheric capacitor with a wire mesh as the outer electrode on ground potential and the sampling substrates as the inner electrode on +7.0 kV. Negatively charged and neutral thoron decay products are accelerated to and deposited on the sampling substrates. As sampling substrates, CR39 solid-state nuclear track detectors are used in order to record the alpha decay of the sampled decay products. Nuclide discrimination is achieved by covering the detectors with aluminum foil of different thickness, which are penetrated only by alpha particles with sufficient energy. Devices of this type were calibrated against working level monitors in a thoron experimental house. The sensitivity was measured as 9.2 tracks per Bq/m(3) × d of thoron decay products. The devices were used over 8 weeks in several houses built of earthen material in southern Germany, where equilibrium equivalent concentrations of 1.4-9.9 Bq/m(3) of thoron decay products were measured.

Field experience on indoor radon, thoron and their progenies with solid-state detectors in a survey of Kosovo and Metohija (Balkan region).

PubMed

Gulan, L; Milic, G; Bossew, P; Omori, Y; Ishikawa, T; Mishra, R; Mayya, Y S; Stojanovska, Z; Nikezic, D; Vuckovic, B; Zunic, Z S

2012-11-01

Since 1996/97, indoor radon has been measured in scattered locations around Kosovo. In the most recent campaign, apart from radon, thoron and Rn and Tn progenies have also been measured. The current survey involves 48 houses, in which different detectors have been deployed side-by-side in one room, in order to measure indoor radon and thoron gas with RADUET devices based on CR-39 detectors (analysed by Japanese collaborators) and with direct thoron and radon progeny sensor (DTPS and DRPS) devices based on LR-115 detectors (analysed by collaborators from India). Estimated arithmetic mean values of concentrations in 48 houses are 122 Bq m(-3) for radon and 136 Bq m(-3) for thoron. Those for equilibrium equivalent radon concentration and equilibrium equivalent thoron concentration based on measurements in 48 houses are 40 and 2.1 Bq m(-3), respectively. The arithmetic mean value of the equilibrium factor is estimated to be 0.50 ± 0.23 for radon and 0.037 ± 0.041 for thoron. The preliminary results of these measurements are reported, particularly regarding DTPS and DRPS being set up in real field conditions for the first time in the Balkan region. The results are to be understood under the caveat of open questions related to measurement protocols which yield reproducible and representative results, and to quality assurance of Tn and Rn/Tn progeny measurements in general, some of which are discussed.

Measurements of radon and thoron progeny concentrations in dwellings of Tehri Garhwal, India, using LR-115 deposition-based DTPS/DRPS technique.

PubMed

Prasad, Mukesh; Rawat, Mukesh; Dangwal, Anoop; Yadav, Manjulata; Gusain, G S; Mishra, Rosaline; Ramola, R C

2015-11-01

This paper presents the values of radon and thoron progeny concentrations for different seasons in the dwellings of Tehri Garhwal, India. The measurements have been carried out using LR-115 solid-state nuclear track detector-based passive time-integrated direct thoron progeny sensor/direct radon progeny sensor technique. In summer, the radon and thoron progeny have been found to vary from 5.7±0.8 to 153.2±4.3 Bq m(-3) with an average of 37.6 Bq m(-3) and 0.3±0.06 to 3.2±0.19 Bq m(-3) with an average of 1.3 Bq m(-3), respectively. In the rainy season, the radon and thoron progeny have been found to vary from 3.2±0.6 to 120±3.7 Bq m(-3) with an average of 58.2 Bq m(-3) and 0.2±0.05 to 11.3±0.37 Bq m(-3) with an average of 3.4 Bq m(-3), respectively. In autumn, the radon and thoron progeny have been found to vary from 4.1±0.7 to 374.4±6.7 Bq m(-3) with an average of 95.6 Bq m(-3) and from 0.3±0.06 to 30.5±0.60 Bq m(-3) with an average of 6.6 Bq m(-3), respectively. In winter, the radon and thoron progeny have been found to vary from 9.8±1.1 to 188.9±4.8 Bq m(-3) with an average of 70.7 Bq m(-3) and 0.1±0.03 to 7.5±0.30 Bq m(-3) with an average of 2.3 Bq m(-3), respectively. It has been observed that the average value of radon and thoron progeny concentrations is maximum for autumn and minimum for summer seasons. The seasonal variations in radon and thoron progeny concentrations in different houses are discussed in detail. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The thoron-tartaric acid systems for the spectrophotometric determination of thorium

USGS Publications Warehouse

Grimaldi, F.S.; Fletcher, Mary H.

1955-01-01

Thoron is popularly used for the spectrophotometric determination of thorium.  An undesirable feature of its use is the high sensitivity of the reagent toward zirconium. This study describes the use of tartaric acid as a masking reagent for zirconium. Three tartaric acid-thoron systems, developed for the determination of thorium, differ with respect to the concentrations of thoron and tartaric acid. Mesotataric acid, used in one of the systems, is found to be most effective in masking zirconium. The behavior of various rarer elements, usually found associated with thorium ores, is determined in two of the systems, and a dilution method is described for the direct determination of thorium in monazite concentrates.

Diurnal variations of radon and thoron activity concentrations and effective doses in dwellings in Niška Banja, Serbia.

PubMed

Vaupotič, J; Streil, T; Tokonami, S; Žunic, Z S

2013-12-01

In Niška Banja, a spa town in a radon-prone area in southern Serbia, radon ((222)Rn) and thoron ((220)Rn) activity concentrations were measured continuously for one day in indoor air of 10 dwellings with a SARAD RTM 2010-2 Radon/Thoron Monitor, and equilibrium factor between radon and its decay products and the fraction of unattached radon decay products with a SARAD EQF 3020-2 Equilibrium Factor Monitor. Radon concentration in winter time ranged from 26 to 73 100 Bq m(-3) and that of thoron, from 10 to 8650 Bq m(-3). In the same period, equilibrium factor and the unattached fraction varied in the range of 0.08 to 0.90 and 0.01 to 0.27, respectively. One-day effective doses were calculated and were in winter conditions from 4 to 2599 μSv d(-1) for radon and from 0.2 to 73 μSv d(-1) for thoron.

Alpha particle spectroscopy in radon/thoron progeny measurements.

PubMed

Thiessen, N P

1994-12-01

A comparison is made between the relative variances and counting time requirements for obtaining radon and thoron progeny air concentrations from total alpha count data and from spectroscopically resolved alpha count data collected from air sampling filters. Spectral resolution is shown to have significant advantages, especially in mixed radon/thoron atmospheres. Systematic biases resulting from imperfect energy peak resolution are shown to be subject to accurate mathematical compensation.

A study of indoor radon, thoron and their exhalation rates in the environment of Fazilka district, Punjab, India

NASA Astrophysics Data System (ADS)

Narang, Saurabh; Kumar, Deepak; Sharma, Dinesh Kumar; Kumar, Ajay

2018-02-01

Over the last few decades, the study of radioactive radon gas has gained huge momentum due to its possible role in health related hazards. In the present work, pin-hole twin chamber single entrance dosimeters have been used for track measurements of radon and thoron. The annual average radon concentration varies from 50.3 to 204 Bq/m3 at all locations. Almost all the values are below the safe range provided by ICRP. Radon concentration is found to be higher in winter as compared to other seasons. Variation of radon with quality of dwellings is also discussed. The values of annual effective dose due to radon and thoron are also well within the range provided by ICRP and WHO. Radon and thoron exhalation rates are measured using SMART RnDuo monitor. The radon mass exhalation rates ranged from 11 to 71 mBq/kg/h while the thoron surface values ranged from 36 to 2048 Bq/m2/h. All the values are on the lower side. A weak correlation is found between radon and thoron concentrations and their exhalation rates. When compared with the values of other parts of northern India, the values of present investigation are on higher side.

Inhalation Dose and Source Term Studies in a Tribal Area of Wayanad, Kerala, India

PubMed Central

Damodaran, Ravikumar C.; Kumar, Visnuprasad Ashok; Panakal John, Jojo; Bangaru, Danalakshmi; Natarajan, Chitra; Sathiamurthy, Bala Sundar; Mundiyanikal Thomas, Jose; Mishra, Rosaline

2017-01-01

Among radiation exposure pathways to human beings, inhalation dose is the most prominent one. Radon, thoron, and their progeny contribute more than 50 per cent to the annual effective dose due to natural radioactivity. South west coast of India is classified as a High Natural Background Radioactivity Area and large scale data on natural radioactivity and dosimetry are available from these coastal regions including the Neendakara-Chavara belt in the south of Kerala. However, similar studies and reports from the northern part of Kerala are scarce. The present study involves the data collection and analysis of radon, thoron, and progeny concentration in the Wayanad district of Kerala. The radon concentration was found to be within a range of 12–378 Bq/m3. The thoron concentration varied from 15 to 621 Bq/m3. Progeny concentration of radon and thoron and the diurnal variation of radon were also studied. In order to assess source term, wall and floor exhalation studies have been done for the houses showing elevated concentration of radon and thoron. The average values of radon, thoron, and their progeny are found to be above the Indian average as well as the average values reported from the High Natural Background Radioactivity Areas of Kerala. Exhalation studies of the soil samples collected from the vicinity of the houses show that radon mass exhalation rate varied from below detectable limit (BDL) to a maximum of 80 mBq/kg/h. The thoron surface exhalation rate ranged from BDL to 17470 Bq/m2/h. PMID:28611847

MEASUREMENT OF RADON, THORON AND THEIR PROGENY IN DIFFERENT TYPES OF DWELLING IN ALMORA DISTRICT OF KUMAUN HIMALAYAN REGION.

PubMed

Singh, Kuldeep; Semwal, Poonam; Pant, Preeti; Gusain, G S; Joshi, Manish; Sapra, B K; Ramola, R C

2016-10-01

The indoor concentrations of radon ( 222 Rn), thoron ( 220 Rn) and their daughter products were measured in the dwellings of Almora district in Kumaun Himalaya, India using pin-hole dosemeters and deposition progeny sensors. The measurements were made in the residential houses built of mud, stone with cement plaster and cemented house during winter season. Average [geometric mean (GM) values] radon and thoron concentrations for all dwellings were found to be 99.82 and 79.70 Bq m -3 , respectively, while average equilibrium equivalent radon concentration and equilibrium equivalent thoron concentration (measured for the first time for this region) were measured at 35.22 and 2.52 Bq m -3 , respectively. Radon concentration (GM values) was found to be 110.73, 97.00 and 93.85 Bq m -3 for mud houses, stone with cemented plaster houses and cemented houses, respectively. On the other hand, thoron concentration values were 87.10, 75.79 and 75.68 Bq m -3 for cemented houses, mud houses and stone with cemented plaster houses, respectively. Interpretations have been made on the basis of measured radon/thoron and progeny concentration values with respect to the difference of construction material of the dwellings. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

Prasad, Mukesh; Rawat, Mukesh; Dangwal, Anoop; Kandari, Tushar; Gusain, G S; Mishra, Rosaline; Ramola, R C

2016-01-01

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analysis of radon and thoron progeny measurements based on air filtration.

PubMed

Stajic, J M; Nikezic, D

2015-02-01

Measuring of radon and thoron progeny concentrations in air, based on air filtration, was analysed in order to assess the reliability of the method. Changes of radon and thoron progeny activities on the filter during and after air sampling were investigated. Simulation experiments were performed involving realistic measuring parameters. The sensitivity of results (radon and thoron concentrations in air) to the variations of alpha counting in three and five intervals was studied. The concentration of (218)Po showed up to be the most sensitive to these changes, as was expected because of its short half-life. The well-known method for measuring of progeny concentrations based on air filtration is rather unreliable and obtaining unrealistic or incorrect results appears to be quite possible. A simple method for quick estimation of radon potential alpha energy concentration (PAEC), based on measurements of alpha activity in a saturation regime, was proposed. Thoron PAEC can be determined from the saturation activity on the filter, through beta or alpha measurements. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Data on the effect of geological and meteorological parameters on indoor radon and thoron level- case study: Kermanshah, Iran.

PubMed

Pirsaheb, Meghdad; Najafi, Farid; Hemati, Lida; Khosravi, Touba; Sharafi, Hooshmand

2018-06-01

The present study was aimed to evaluate the relationship between indoor radon and thoron concentrations, geological and meteorological parameters. The radon and thoron concentrations were determined in three hospitals in Kermanshah, the west part of Iran, using the RTM-1688-2 radon meter. Also, the type and porosity of the underlying soil and the meteorological parameters such as temperature, humidity, atmospheric pressure, rainfall and wind speed were studied and the obtained results analyzed using STATA-Ver.8. In this study the obtained radon concentration was furthered in buildings which constructed on the soil with clayey gravel and sand feature than the soil with clay characteristic and little pasty with a significant difference ( P < 0.05). While the lower coefficient about 1.3 was obtained in measured the thoron concentration and a significant difference was not observed. So the soil porosity can extremely effect on the indoor radon amount. Among all studied meteorological parameters, temperature has been determined as the most important meteorological parameter, influence the indoor radon and thoron concentrations.

The influence of environmental factors on the deposition velocity of thoron progeny.

PubMed

Li, H; Zhang, L; Guo, Q

2012-11-01

Passive measuring devices are comprehensively employed in thoron progeny surveys, while the deposition velocity of thoron progeny is the most critical parameter, which varies in different environments. In this study, to analyse the influence of environmental factors on thoron progeny deposition velocity, an improved model was proposed on the basis of Lai's aerosol deposition model and the Jacobi's model, and a series of measurements were carried out to verify the model. According to the calculations, deposition velocity decreases with increasing aerosol diameter and also aerosol concentration, while increases with increasing ventilation rate. In typical indoor environments, a typical value of 1.26 × 10(-5)m s(-1) is recommended, with a range between 7.6 × 10(-7) and 3.2 × 10(-4) m s(-1).

Invited Article: In situ comparison of passive radon-thoron discriminative monitors at subsurface workplaces in Hungary

NASA Astrophysics Data System (ADS)

Kávási, Norbert; Vigh, Tamás; Németh, Csaba; Ishikawa, Tetsuo; Omori, Yasutaka; Janik, Miroslaw; Yonehara, Hidenori

2014-02-01

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.

STUDY OF RADIATION EXPOSURE DUE TO RADON, THORON AND PROGENY IN THE INDOOR ENVIRONMENT OF YAMUNA AND TONS VALLEYS OF GARHWAL HIMALAYA.

PubMed

Prasad, Mukesh; Rawat, Mukesh; Dangwal, Anoop; Prasad, Ganesh; Mishra, Rosaline; Ramola, R C

2016-10-01

Long-term measurements of indoor radon, thoron and their progeny concentrations have been carried out in dwellings of Yamuna and Tons Valleys of Uttarkashi, Garhwal Himalaya to investigate the health risk associated with inhalation of radon, thoron and progeny. The experimentally determined values of radon, thoron and progeny concentrations were used to estimate the annual inhalation doses and annual effective doses. The annual inhalation dose has been found to vary from 0.8 to 3.9 mSv y -1 with an average of 1.8 mSv y -1 The annual effective dose from the exposure to radon and its progeny in the study area has been found to vary from 0.1 to 2.4 mSv with an average of 1.2±0.6 mSv. Similarly, the annual effective dose due to thoron and its progeny has been found to vary from 0.2 to 1.5 mSv with an average of 0.6±0.4. The measurement techniques and results obtained are discussed in detail. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Indoor concentration of radon, thoron and their progeny around granite regions in the state of Karnataka, India.

PubMed

Sannappa, J; Ningappa, C

2014-03-01

An extensive studies on the indoor activity concentrations of thoron, radon and their progeny in the granite region in the state of Karnataka, India, has been carried out since, 2007 in the scope of a lung cancer epidemiological study using solid-state nuclear track detector-based double-chamber dosemeters (LR-115, type II plastic track detector). Seventy-four dwellings of different types were selected for the measurement. The dosemeters containing SSNTD detectors were fixed 2 m above the floor. After an exposure time of 3 months (90 d), films were etched to reveal tracks. From the track density, the concentrations of radon and thoron were evaluated. The value of the indoor concentration of thoron and radon in the study area varies from 16 to 170 Bq m(-3) and 18 to 300 Bq m(-3) with medians of 66 and 82.3 Bq m(-3), respectively, and that of their progeny varies from 1.8 to 24 mWL with a median of 3.6 mWL and 1.6 to 19.6 mWL, respectively. The concentrations of indoor thoron, radon and their progeny and their equivalent effective doses are discussed.

Optimization of the Timepix chip to measurement of radon, thoron and their progenies.

PubMed

Janik, Miroslaw; Ploc, Ondrej; Fiederle, Michael; Procz, Simon; Kavasi, Norbert

2016-01-01

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 (241)Am and(210)Po 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 r(2) 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

MEASUREMENT OF INDOOR RADON-THORON IN AIR AND EXHALATION FROM SOIL IN THE ENVIRONMENT OF WESTERN HARYANA, INDIA.

PubMed

Mann, Nisha; Kumar, Amit; Kumar, Sushil; Chauhan, R P

2016-10-01

Measurement of indoor radon and thoron is important because the inhalation of radon-thoron and their daughters contributes more than 50 % of the total dose from natural sources. One of the important parameters to find out the contribution of soil and building materials towards indoor radon is radon exhalation rates, which can be used for estimation of indoor radon levels. The indoor radon and thoron levels from the air and radon exhalation rates from soil samples collected from two districts (Hisar and Fatehabad) of Western Haryana are measured using pin-hole-based radon-thoron dosimeter and LR-115 solid-state nuclear track detector by canister technique. The results show that the indoor radon and thoron levels from Hisar district varied from 11 to 112 and 11 to 80 Bq m -3 , while for Fatehabad district from 5 to 24 and 59 to 105 Bq m -3 , respectively, in summer season. In winter season, indoor radon and thoron levels from Hisar district varied from 15 to 43 and 32 to 102 Bq m -3 , while for Fatehabad district from 18 to 31 and 11 to 80 Bq m -3 , respectively. The indoor radon levels of 95 % locations lie well below the limit recommended by International Commission of Radiation Protection, 2011. The radon mass exhalation rate varied from 6 to 56 mBq kg -1 h -1 The radon mass exhalation rates from the soil samples were lower than the worldwide average, i.e. 56 mBq kg -1 h -1 There exists a poor correlation between indoor radon and exhalation rates. More investigations of measurement of radionuclide contents from rock and stone of study area can improve the understanding. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Inhalation dose due to radon, thoron, and progenies in dwellings of a hill station.

PubMed

Sivakumar, R

2017-02-01

The general public spends a major portion of their time in an indoor environment and hence receives a considerable amount of radiation. Knowledge about indoor radiation is important in order to arrive at the actual effective dose received by residents. The indoor radon, thoron, and progeny concentrations observed in the present study were found to vary with seasons of a given year. The highest and lowest indoor average radon, thoron, and progeny levels were observed during winter and summer seasons, respectively. The concentrations of indoor radon, thoron, and progenies were found to vary with the type of houses. The highest 222 Rn, 220 Rn, and progeny concentrations were observed in mud houses and the lowest values were recorded in wooden houses. The indoor 222 Rn concentration correlated well with concentration of its grandparent 238 U in underlying soil with a correlation coefficient of 0.87. The correlation between indoor 220 Rn and 232 Th in the underlying soil was found to be 0.64. The estimated effective doses received by the general public in the present study due to indoor radon and thoron were 1.49 ± 0.49 and 1.30 ± 0.53 mSv/year, respectively. The annual effective doses due to radon and thoron progenies were estimated as 0.76 ± 0.27 and 0.47 ± 0.23 mSv/year, respectively. The contributions from 222 Rn, 220 Rn, and corresponding progenies to the annual effective doses received were 37, 32, 19, and 12%, respectively. The general public living in the study area receives an inhalation dose of 4.02 mSv/year due to indoor radon, thoron, and progenies, which were found to be less than the action limit of ICRP 2009.

INDOOR RADON, THORON AND THEIR PROGENY CONCENTRATIONS IN HIGH THORON RURAL SERBIA ENVIRONMENTS.

PubMed

Zunic, Zora S; Stojanovska, Z; Veselinovic, N; Mishra, R; Yarmoshenko, I V; Sapra, B K; Ishikawa, T; Omori, Y; Curguz, Z; Bossew, P; Udovicic, V; Ramola, R C

2017-11-01

This article deals with the variation of radon (Rn), thoron (Tn) and their progeny concentrations expressed in terms of equilibrium equivalent concentrations (EERC and EETC), in 40 houses, in four villages of Sokobanja municipality, Southern Serbia. Two types of passive detectors were used: (1) discriminative radon-thoron detector for simultaneous Rn and Tn gases measurements and (2) direct Tn and Rn progeny sensors (DRPS/DTPS) for measuring Rn and Tn progeny concentrations. Detectors were exposed simultaneously for a single period of 12 months. Variations of Tn and EETC appear higher than those of Rn and EERC. Analysis of the spatial variation of the measured concentrations is also reported. This work is part of a wider survey of Rn, Tn and their progeny concentrations in indoor environments throughout the Balkan region started in 2011 year. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Determination of the volume activity concentration of alpha artificial radionuclides with alpha spectrometer.

PubMed

Liu, B; Zhang, Q; Li, Y

1997-12-01

This paper introduces a method to determine the volume activity concentration of alpha and/or beta artificial radionuclides in the environment and radon/thoron progeny background-compensation based on a Si surface-barrier detector. By measuring the alpha peak counts of 218Po and 214Po in two time intervals, the activity concentration of 218Po, 214Pb and 214Bi aerosol particles were determined; meanwhile, the total beta count of 214Pb and 214Bi aerosols was also calculated from their decay scheme. With the average equilibrium factor of thoron progeny in general environment, the alpha and beta counts of thoron progeny were approximately evaluated by 212Po alpha peak counts. The alpha count of transuranic aerosols was determined by subtracting the trail counts of radon/thoron progeny alpha peaks. The total count of beta artificial radionuclides was determined by subtracting the beta counts of radon/thoron progeny aerosol particles. In our preliminary experiments, if the radon progeny concentration is less than 15 Bq m(-3), the lower limit of detection of transuranics concentration is less than 0.1 Bq m(-3). Even if the radon progeny concentration is as high as 75 Bq m(-3), the lower limit of detection of total beta activity concentration of artificial nuclides aerosols is less than 1 Bq m(-3).

Invited Article: In situ comparison of passive radon-thoron discriminative monitors at subsurface workplaces in Hungary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kávási, Norbert, E-mail: norbert@fml.nirs.go.jp; Social Organization for Radioecological Cleanliness, Veszprém; Vigh, Tamás

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{sup −1}) and low or elevated aerosol concentration (130–60 000 particles m{sup −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 (inmore » 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{sup −3} and 550(497) Bq m{sup −3} in the bauxite mine; 887(604) Bq m{sup −3} and 1258(788) Bq m{sup −3} in the manganese ore mine; 2510(2341) Bq m{sup −3} and 3403(3075) Bq m{sup −3} in the medical cave (Hospital Cave of Tapolca); and 6239(2057) Bq m{sup −3} and 8512(1955) Bq m{sup −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{sup −3} and 161(148) Bq m{sup −3} in the bauxite mine; 187(191) Bq m{sup −3} and 117(147) Bq m{sup −3} in the manganese-ore mine; 360(524) Bq m{sup −3} and 371(789) Bq m{sup −3} in the medical cave (Hospital Cave of Tapolca); and 1420(1184) Bq m{sup −3} and 1462(3655) Bq m{sup −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.« less

A new passive radon-thoron discriminative measurement system.

PubMed

Sciocchetti, G; Sciocchetti, A; Giovannoli, P; DeFelice, P; Cardellini, F; Cotellessa, G; Pagliari, M

2010-10-01

A new passive radon-thoron discriminative measurement system has been developed for monitoring radon and thoron individually. It consists of a 'couple' of passive integrating devices with a CR39 nuclear track detector (NTD). The experimental prototype is based on the application of a new concept of NTD instrument developed at ENEA, named Alpha-PREM, acronym of piston radon exposure meter, which allows controlling the detector exposure with a patented sampling technique (Int. Eu. Pat. and US Pat.). The 'twin diffusion chambers system' was based on two A-PREM devices consisting of the standard device, named NTD-Rn, and a modified version, named NTD-Rn/Tn, which was set up to improve thoron sampling efficiency of the diffusion chamber, without changing the geometry and the start/stop function of the NTD-Rn device. Coupling devices fitted on each device allowed getting a system, which works as a double-chamber structure when deployed at the monitoring position. In this paper both technical and physical aspects are considered.

Portable apparatus for the measurement of environmental radon and thoron

DOEpatents

Negro, Vincent C.

2001-01-01

The radometer is a portable instrument for the measurement of the concentration of atmospheric radon/thoron in a test area. A constant velocity pump pulls the air from the outside at a constant flow rate. If the air is too moist, some or all of the sample is passed through a desiccant filter prior to encountering an electrostatic filter. The electrostatic filter prevents any charged particles from entering the sampling chamber. Once the sample has entered the chamber, the progeny of the decay of radon/thoron are collected on a detector and measured. The measured data is compiled by a computer and displayed.

Study of indoor radon and thoron progeny levels in surrounding areas of Nalbari, Assam, India

NASA Astrophysics Data System (ADS)

Deka, P. C.; Sarma, H.; Sarkar, Subir; Goswami, T. D.; Sarma, B. K.

2009-07-01

With the growing understanding of the role of radon and its daughter products as major sources of radiation exposure, the importance of large number of estimation of radon concentration in various parts of the country is realized. Inhalation of radon, thoron and their decay products is the major source of the total radioactive dose received by the human population from natural radiation. The indoor radon and thoron progeny levels in Nalbari area of Assam are studied by using the LR-115 (type II) Solid State Nuclear Track Detector in Plastic Twin Chamber dosimeter. Radon and thoron progeny levels in different types of dwellings for one full calendar year are presented in this paper. For Assam Type (A.T.) houses, indoor radon progeny concentrations vary from 0.17 to 0.64 mWL with an annual geometric mean of 0.27 mWL and that for Reinforced Cement Concrete (R.C.C.) houses vary from 0.22 mWL to 0.60 mWL with the annual geometric mean of 0.37 mWL. The thoron progeny levels in A.T. houses also vary from 0.01 to of 0.05 mWL with an annual geometric mean of 0.02 mWL and that for R.C.C. houses vary from 0.02 to 0.08 mWL with the annual geometric mean of 0.04 mWL.

Internal exposure from building materials exhaling (222)Rn and (220)Rn as compared to external exposure due to their natural radioactivity content.

PubMed

Ujić, Predrag; Celiković, Igor; Kandić, Aleksandar; Vukanac, Ivana; Durasević, Mirjana; Dragosavac, Dusan; Zunić, Zora S

2010-01-01

The main scope of this paper is to point out the importance of introducing radon and thoron exhalation measurements from building materials in the regulating frame. Currently (2009), such a regulation of this kind of exposure is not explicitly included in the Serbian regulating network. To this end, this work reports concentration measurements of (226)Ra, (232)Th and (40)K and radon and thoron exhalation rates from building materials used in Serbia. Following detailed analysis, it was noticed that both internal exposures to radon and/or thoron exhaling from building materials may exceed external exposures to their precursors contained therein.

Monte Carlo simulation of semiconductor detector response to (222)Rn and (220)Rn environments.

PubMed

Irlinger, J; Trinkl, S; Wielunksi, M; Tschiersch, J; Rühm, W

2016-07-01

A new electronic radon/thoron monitor employing semiconductor detectors based on a passive diffusion chamber design has been recently developed at the Helmholtz Zentrum München (HMGU). This device allows for acquisition of alpha particle energy spectra, in order to distinguish alpha particles originating from radon and radon progeny decays, as well as those originating from thoron and its progeny decays. A Monte-Carlo application is described which uses the Geant4 toolkit to simulate these alpha particle spectra. Reasonable agreement between measured and simulated spectra were obtained for both (220)Rn and (222)Rn, in the energy range between 1 and 10 MeV. Measured calibration factors could be reproduced by the simulation, given the uncertainties involved in the measurement and simulation. The simulated alpha particle spectra can now be used to interpret spectra measured in mixed radon/thoron atmospheres. The results agreed well with measurements performed in both radon and thoron gas environments. It is concluded that the developed simulation allows for an accurate prediction of calibration factors and alpha particle energy spectra. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparative Measurements of Radon Concentration in Soil Using Passive and Active Methods in High Level Natural Radiation Area (HLNRA) of Ramsar

PubMed Central

Amanat, B; Kardan, M R; Faghihi, R; Hosseini Pooya, S M

2013-01-01

Background: Radon and its daughters are amongst the most important sources of natural exposure in the world. Soil is one of the significant sources of radon/thoron due to both radium and thorium so that the emanated thoron from it may cause increased uncertainties in radon measurements. Recently, a diffusion chamber has been designed and optimized for passive discriminative measurements of radon/thoron concentrations in soil. Objective: In order to evaluate the capability of the passive method, some comparative measurements (with active methods) have been performed. Method: The method is based upon measurements by a diffusion chamber, including two Lexan polycarbonate SSNTDs, which can discriminate the emanated radon/thorn from the soil by delay method. The comparative measurements have been done in ten selected points of HLNRA of Ramsar in Iran. The linear regression and correlation between the results of two methods have been studied. Results: The results show that the radon concentrations are within the range of 12.1 to 165 kBq/m3 values. The correlation between the results of active and passive methods was measured by 0.99 value. As well, the thoron concentrations have been measured between 1.9 to 29.5 kBq/m3 values at the points. Conclusion: The sensitivity as well as the strong correlation with active measurements shows that the new low-cost passive method is appropriate for accurate seasonal measurements of radon and thoron concentration in soil. PMID:25505760

Preliminary radiological safety assessment for decommissioning of thoria dissolver of the ²³³U pilot plant, Trombay.

PubMed

Priya, S; Srinivasan, P; Gopalakrishnan, R K

2012-01-01

The thoria dissolver, used for separation of (233)U from reactor-irradiated thorium metal and thorium oxide rods, is no longer operational. It was decided to carry out assessment of the radiological status of the dissolver cell for planning of the future decommissioning/dismantling operations. The dissolver interiors are expected to be contaminated with the dissolution remains of irradiated thorium oxide rods in addition to some of the partially dissolved thoria pellets. Hence, (220)Rn, a daughter product of (228)Th is of major radiological concern. Airborne activity of thoron daughters (212)Pb (Th-B) and (212)Bi (Th-C) was estimated by air sampling followed by high-resolution gamma spectrometry of filter papers. By measuring the full-energy peaks counts in the energy windows of (212)Pb, (212)Bi and (208)Tl, concentrations of thoron progeny in the sampled air were estimated by applying the respective intrinsic peak efficiency factors and suitable correction factors for the equilibration effects of (212)Pb and (212)Bi in the filter paper during the delay between sampling and counting. Then the thoron working level (TWL) was evaluated using the International Commission on Radiological Protection (ICRP) methodology. Finally, the potential effective dose to the workers, due to inhalation of thoron and its progeny during dismantling operations was assessed by using dose conversion factors recommended by ICRP. Analysis of filter papers showed a maximum airborne thoron progeny concentration of 30 TWLs inside the dissolver.

Studies on radon/thoron and their decay products in granite quarries around Bangalore city, India

NASA Astrophysics Data System (ADS)

Ningappa, C.; Sannappa, J.; Chandrashekara, M. S.; Paramesh, L.

2009-08-01

The radon survey was performed in granite quarries around Bangalore rural district and Bangalore city as part of a lung cancer epidemiological study. Long duration measurements of indoor and outdoor radon, thoron and their progenies concentrations were made around granite quarries of Bangalore rural district by using Solid State Nuclear Track Detector (SSNTD, LR-115, Type-II Plastic track detector) during summer and winter period (2006-07). The increase of radioactivity in granite quarries and inhalation dose to workers and populations near the quarries have been summarized. The higher concentrations of radon and thoron in granite quarries suggest radiation health effects on workers and public around the quarries is higher than permissible levels. The results are presented and analyzed with reference to ICRP limits.

Inhalation Toxicology Research Institute Annual Report, 1992-1993

DTIC Science & Technology

1993-11-01

for Mineral and Energy Technology ( CANMET ). The ITRI team participated in all phases of the intercomparison studies. The methods, procedures, and...differential cloning, and differential hybridization techniques. However, with recent advances in polymerase chain reaction (PCR) technology , an...viii I. AEROSOL TECHNOLOGY AND CHARACTERIZATION OF AIRBORNE MATERIALS Measurement of Thoron and Thoron/Radon Mixtures Y. S. Cheng and H. C. Yeh Use of a

2014 ICHLNRRA intercomparison of radon/thoron gas and radon short-lived decay products measuring instruments in the NRPI Prague.

PubMed

Jílek, K; Timková, J

2015-06-01

During the Eighth International Conference on High Levels of Natural Radiation and Radon Areas held in autumn 2014 at Prague, the third intercomparison of radon/thoron gas and radon short-lived decay products measurement instruments was organised by and held at the Natural Radiation Division of the National Radiation Protection Institute (NRPI; SÚRO v.v.i.) in Prague. The intercomparison was newly focussed also on continuous monitors with active sampling adapters capable to distinguish radon/thoron gas in their mix field.The results of radon gas measurements carried out in the big NRPI radon chamber indicated very well an average deviation of up to 5 % from the reference NRPI value for 80 % of all the exposed instruments. The results of equilibrium equivalent concentration continuous monitors indicated an average deviation of up to 5 % from the reference NRPI value for 40 % of all the exposed instruments and their ~8-10 % shift compared with the NRPI. The results of investigated ambient conditions upon response of exposed continuous monitors indicated influence of aerosol changes upon response of radon monitors with an active air sampling adapters through the filter, only. The exposures of both radon/thoron gas discriminative continuous monitors and passive detectors have been indicated inconsistent results: on one hand, their excellent agreement up to several per cent for both the gases, and on the other hand, systematic unsatisfactory differences up to 40 %. Additional radon/thoron exercises are recommended to improve both the instruments themselves and quality of their operators. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

Kumar, Ajay; Sharma, Sumit; Mehra, Rohit; Narang, Saurabh; Mishra, Rosaline

2017-07-01

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

Improved automated analysis of radon (222Rn) and thoron (220Rn) in natural waters.

PubMed

Dimova, Natasha; Burnett, William C; Lane-Smith, Derek

2009-11-15

Natural radon ((222)Rn) and thoron ((220)Rn) can be used as tracers of various chemical and physical processes in the environment. We present here results from an extended series of laboratory experiments intended to improve the automated analysis of (222)Rn and (220)Rn in water using a modified RAD AQUA (Durridge Inc.) system. Previous experience with similar equipment showed that it takes about 30-40 min for the system to equilibrate to radon-in-water concentration increases and even longer for the response to return to baseline after a sharp spike. While the original water/gas exchanger setup was built only for radon-in-water measurement, our goal here is to provide an automated system capable of high resolution and good sensitivity for both radon- and thoron-in-water detections. We found that faster water flow rates substantially improved the response for both isotopes while thoron is detected most efficiently at airflow rates of 3 L/min. Our results show that the optimum conditions for fastest response and sensitivity for both isotopes are at water flow rates up to 17 L/min and an airflow rate of 3 L/min through the detector. Applications for such measurements include prospecting for naturally occurring radioactive material (NORM) in pipelines and locating points of groundwater/surface water interaction.

Thoron-meso-tartaric acid system for determination of thorium

USGS Publications Warehouse

Fletcher, M.H.; Grimaldi, F.S.; Jenkins, L.B.

1957-01-01

In the spectrophotometric determination of thorium with thoron, mesotartaric acid is used as a masking reagent for zirconium. The effects of different experimental variables such as the concentrations of the reagents, time, and temperature, and the behavior of 35 ions which might be present in thorium ores are discussed. A dilution procedure is given for the direct determination of thorium in zircon (ZrSiO4) that is also generally applicable to other materials.

STUDY OF RADON, THORON EXHALATION AND NATURAL RADIOACTIVITY IN COAL AND FLY ASH SAMPLES OF KOTA SUPER THERMAL POWER PLANT, RAJASTHAN, INDIA.

PubMed

Singh, Lalit Mohan; Kumar, Mukesh; Sahoo, B K; Sapra, B K; Kumar, Rajesh

2016-10-01

Electricity generation in India is largely dependent on coal-based thermal power plants, and increasing demand of energy raised the coal consumption in the power plants. In recent years, study of natural radioactivity content and radon/thoron exhalation from combustion of coal and its by-products has given considerable attention as they have been recognised as one of the important technically enhanced naturally occurring radioactive materials. In the present study, radon, thoron exhalation rate and the radioactivity concentration of radionuclides in coal and fly ash samples collected from Kota Super Thermal Power Plant, Rajasthan, India have been measured and compared with data of natural soil samples. The results have been analysed and discussed. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Radon and Thoron In-air Occupational Exposure Study within Selected Wine Cellars of the Western Cape (South Africa) and Associated Annual Effective Doses.

PubMed

Botha, R; Newman, R T; Lindsay, R; Maleka, P P

2017-01-01

This is the first known study of exposure of Rn (radon) and secondarily Rn (thoron) in-air activity concentrations assessed within nine selected wine cellars in four wine districts of the Western Cape (South Africa) and the associated annual occupational effective doses. E-PERM electret ion chambers (EIC) and RAD-7 α-detectors were used to perform these measurements. The radon in-air levels ranged from 12 ± 4 Bq m to 770 ± 40 Bq m within the nine selected wine cellars. Eight of the nine wine cellars (excluding results from cellar w-6) had a median radon in-air activity concentration of 48 ± 8 Bq m. Continuous thoron in-air activity concentration levels were also measured near an internal granite wall of the wine cellar w-6 (barrel room), where peak levels of up to 1,520 ± 190 Bq m and an average of 680 ± 30 Bq m were observed. The occupational annual effective dose due to radon and decay progeny exposure in-air within the selected wine cellars ranged from 0.08 ± 0.03 mSv to 4.9 ± 0.3 mSv with a median of 0.32 ± 0.04 mSv (Tmax = 2,000 h). The annual effective dose within the wine cellar (w-6) ranged up to a maximum of 2.5 ± 0.4 mSv (Tmax = 2000 h) due to exposure to thoron and decay progeny. In general, most of the wines cellars pose negligible associated health risk to personnel due to ionizing radiation exposure from the inhalation of radon and progeny. Under certain conditions (proximity and exposure time), caution should be exercised at wine cellar w-6 because of elevated thoron in-air levels.

Influence of meteorological parameters on the soil radon (Rn222) emanation in Kutch, Gujarat, India.

PubMed

Sahoo, Sushanta Ku; Katlamudi, Madhusudhanarao; Shaji, Jerin P; Murali Krishna, K S; Udaya Lakshmi, G

2018-02-02

The soil radon (Rn 222 ) and thoron (Rn 220 ) concentrations recorded at Badargadh and Desalpar observatories in the Kutch region of Gujarat, India, have been analyzed to study the sources of the radon emissions, earthquake precursors, and the influence of meteorological parameters on radon emission. Radon and meteorological parameters were recorded using Radon Monitor RMT 1688-2 at these two stations. We used the radon data during February 21, 2011 to June 8, 2011, for Badargadh and March 2, 2011 to May 19, 2011, for the Desalpar station with a sampling interval of 10 min. It is observed that the radon concentrations at Desalpar varies between 781 and 4320 Bq m -3 with an average value of 2499 Bq m -3 , whereas thoron varies between 191 and 2017 Bq m -3 with an average value of 1433.69 Bq m -3 . The radon concentration at Badargadh varies between 264 and 2221 Bq m -3 with an average value of 1135.4 Bq m -3 , whereas thoron varies between 97 and 556 Bq m -3 . To understand how the meteorological parameters influence radon emanation, the radon and other meteorological parameters were correlated with linear regression analysis. Here, it was observed that radon and temperature are negatively correlated whereas radon and other two parameters, i.e., humidity and pressure are positively correlated. The cross correlogram also ascertains similar relationships between radon and other parameters. Further, the ratio between radon and thoron has been analyzed to determine the deep or shallow source of the radon emanation in the study area. These results revealed that the ratio radon/thoron enhanced during this period which indicates the deeper source contribution is prominent. Incidentally, all the local earthquakes occurred with a focal depth of 18-25 km at the lower crust in this region. We observed the rise in the concentrations of radon and the ratio radon/thoron at Badargadh station before the occurrence of the local earthquakes on 29th March 2011 (M 3.7) and 17th May 2011 (M 4.2). We clearly observed the radon level crossing the mean + 2*sigma level before the occurrence of these events. We conclude that these enhanced radon emissions are linked with alteration of the crustal stress/strain in this region as this observing station is near the epicenters of the earthquakes. We did not observe considerable variations in radon at the Desalpar station which is far from the earthquake location.

COMPARATIVE STUDY OF RADON AND THORON MEASUREMENTS IN FOUR ROMANIAN SHOW CAVES.

PubMed

Burghele, B D; Cucos, A; Papp, B; Dicu, T; Pressyanov, D; Dimitrov, D; Dimitrova, I; Constantin, S

2017-11-01

Measurements have been carried out using four types of passive detectors in four of the most popular show caves in Romania. Three types of detectors (RSKS, RadTrak and CD) were used for radon measurements and two (Raduet and CD) for thoron measurement. Activity concentrations in air were measured in the same locations for two seasons, autumn and winter. Measured values for the different caves varied between below detection limit (5 Bq m-3) and 4024 Bq m-3 for radon and from below 10 to 583 Bq m-3 for thoron. The results indicate a very good correlation between RSKS and RadTrak detectors (r = 0.96). The most significant difference between radon concentrations measured with different types of detectors (RSKS and CD) was higher than 150%. The study suggests that the activity concentration of radon in caves, measured using track detectors, could not be influenced by the type of detector used if the microclimate factor is acknowledged. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Controlling 212Bi to 212Pb activity concentration ratio in thoron chambers.

PubMed

He, Zhengzhong; Xiao, Detao; Lv, Lidan; Zhou, Qingzhi; Shan, Jian; Qiu, Shoukang; Wu, Xijun

2017-11-01

It is necessary to establish a reference atmosphere in a thoron chamber containing various ratios of 212 Bi to 212 Pb activity concentrations (C( 212 Bi)/C( 212 Pb)) to simulate typical environmental conditions (e.g., indoor or underground atmospheres). In this study, a novel method was developed for establishing and controlling C( 212 Bi)/C( 212 Pb) in a thoron chamber system based on an aging chamber and air recirculation loops which alter the ventilation rate. The effects of main factors on the C( 212 Bi)/C( 212 Pb) were explored, and a steady-state theoretical model was derived to calculate the ratio. The results show that the C( 212 Bi)/C( 212 Pb) inside the chamber is mainly dependent on ventilation rate. Ratios ranging from 0.33 to 0.83 are available under various ventilation. The stability coefficient of the ratios is better than 7%. The experimental results are close to the theoretical calculated results, which indicates that the model can serve as a guideline for the quantitative control of C( 212 Bi)/C( 212 Pb). Copyright © 2017 Elsevier Ltd. All rights reserved.

AGE-DEPENDENT INHALATION DOSE DUE TO EXPOSURE OF SHORT LIVED PROGENY OF RADON AND THORON FOR DIFFERENT AGE GROUPS IN JAMMU & KASHMIR, HIMALAYAS.

PubMed

Sharma, Sumit; Kumar, Ajay; Mehra, Rohit

2018-05-16

Dosimetric approach is used in this study for the assessment of doses due to inhalation of short lived radon/thoron progeny to the inhabitants of Udhampur district of Jammu & Kashmir. This paper also presents the activity concentrations and unattached fraction of radon and thoron progeny. The observed annual concentration of attached and unattached 222Rn and 220Rn progeny has been found to vary from 8 to 32 and 0.09 to 14 Bq/m3, 0.75 to 3.16 and 0.01 to 1.13 Bq/m3, respectively. The inhalation doses from radon progeny to different body organs of different age groups have been calculated by using the age dependent biokinetic model. The attachment rate of 222Rn and indoor aerosol concentration of 222Rn and 220Rn have been estimated and their relation between them has also been studied. The dose conversion factor for mouth and nasal breathing to different exposure conditions has been obtained from Porstendorfer model.

Passive radon/thoron personal dosimeter using an electrostatic collector and a diffused-junction detector

NASA Astrophysics Data System (ADS)

Bigu, J.; Raz, R.

1985-01-01

A solid-state alpha dosimeter has been designed and tested suitable for personal and environmental radon/thoron monitoring. The dosimeter basically consists of an electrostatic collector and an alpha-particle counting system with spectroscopy capabilities. The sensitive volume (˜20 cm3) of the electrostatic collector consists of a cylindrically shaped metal wire screen and a diffused-junction silicon alpha-detector covered with a thin aluminized Mylar sheet. A dc voltage (˜500 V) is applied between the wire screen and the Mylar sheet, with the latter held at negative potential relative to the former. Data can be retrieved during or after sampling by means of a microcomputer (Epson HX20) via a RS-232 communication interface unit. The dosimeter has been calibrated in a large (26 m3) radon/thoron test facility. A linear relationship was found between the dosimeter's alpha-count and both radon gas concentration and radon daughter working level. The dosimeter is mounted on top of an ordinary miner's cap lamp battery and is ideally suited for personal monitoring in underground uranium mines and other working areas. The dosimeter presented here is a considerably improved version of an earlier prototype.

Spatial distribution of soil radon as a tool to recognize active faulting on an active volcano: the example of Mt. Etna (Italy).

PubMed

Neri, Marco; Giammanco, Salvatore; Ferrera, Elisabetta; Patanè, Giuseppe; Zanon, Vittorio

2011-09-01

This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquakes depth and intensity can give some hints on the source of gas and/or on fault dynamics. Copyright © 2011 Elsevier Ltd. All rights reserved.

Variation of annual effective dose due to radon level in indoor air in Marwar region of Rajasthan, India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rani, Asha, E-mail: ashasachdeva78@gmail.com; Mittal, Sudhir, E-mail: sudhirmittal03@gmail.com; Mehra, Rohit

In the present work, indoor radon and thoron measurements have been carried out from different locations of Jodhpur and Nagaur districts of Northern Rajasthan, India using RAD7, a solid state alpha detector. The radon and thoron concentration in indoor air varies from 8.75 to 61.25 Bq m{sup −3} and 32.7 to 147.2 Bq m{sup −3} with the mean value of 32 and 73 Bq m{sup −3} respectively. The observed indoor radon concentration values are well below the action level recommended by International Commission on Radiological Protection (200-300 Bq m{sup −3}) and Environmental Protection Agency (148 Bq m{sup −3}). The surveymore » reveals that the thoron concentration values in the indoor air are well within the International Commission on Radiological Protection (2005). The calculated total annual effective dose due to radon level in indoor air varies from 0.22 to 1.54 mSv y{sup −1} with the mean value of 0.81 mSv y{sup −1} which is less than even the lower limit of action level 3-10 mSv y{sup −1} recommended by International Commission on Radiological Protection (2005)« less

A COMPARATIVE STUDY OF DIURNAL VARIATION OF RADON AND THORON CONCENTRATIONS IN INDOOR ENVIRONMENT.

PubMed

Pant, Preeti; Kandari, Tushar; Prasad, Mukesh; Ramola, R C

2016-10-01

The diurnal measurements of radon and thoron concentrations were performed in the indoor environment of Nuclear Research Laboratory, Badshahi Thaul, Tehri Garhwal, Uttarakhand, India by using AlphaGUARD, Portable Radon Monitor (SMART RnDuo) and RAD7. Using AlphaGUARD, the radon concentration was found to vary from 8 to 94 Bq m -3 with an average of 41.5±22.2 Bq m -3 Using Portable Radon Monitor (SMART RnDuo), the concentration was found to vary from 2 to 101 Bq m -3 with an average of 41.7±23.6 Bq m -3 , and with RAD7, the concentration was found to vary from 3 to 99 Bq m -3 with an average of 40±20.3 Bqm -3 While the thoron concentration using Portable Radon Monitor (SMART RnDuo) was found to vary from 4 to 65 Bq m -3 with an average of 17.3±12.9 Bqm -3 , and using RAD7, the concentration was found to vary from 5 to 90 Bq m -3 with an average of 29.8±17.3 Bq m -3 . © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Study of Natural Radioactivity, Radon Exhalation Rate and Radiation Doses in Coal and Flyash Samples from Thermal Power Plants, India

NASA Astrophysics Data System (ADS)

Singh, Lalit Mohan; Kumar, Mukesh; Sahoo, B. K.; Sapra, B. K.; Kumar, Rajesh

Coal is one of the most important source used for electrical power generation. Its combustion part known as fly ash is used in the manufacturing of bricks, sheets, cement, land filling etc. Coal and its by-products have significant amounts of radionuclide's including uranium, thorium which is the ultimate source of the radioactive gas radon and thoron respectively. Radiation hazard from airborne emissions of coal-fired power plants have been cited as possible causes of health in environmental. Assessment of the radiation exposure from coal burning is critically dependent on the concentration of radioactive elements in coal and in the fly ash. In the present study, samples of coal and flyash were collected from Rajghat Power Plant and Badarpur Thermal Power Plant, New Delhi, India. Radon exhalation is important parameter for the estimation of radiation risk from various materials. Solis State Nuclear Track Detector based sealed Can Technique (using LR-115 type II) has been used for measurement radon exhalation rate. Also accumulation chamber based Continuous Radon Monitor and Continuous Thoron Monitor have been used for radon masss exhalation and thoron surface exhalation rate respectively. Natural radioactivity has been measured using a low level NaI(Tl) detector based on gamma ray spectrometry.

MEASUREMENTS OF AIRBORNE CONCENTRATIONS OF RADON AND THORON DECAY PRODUCTS.

PubMed

Chalupnik, S; Skubacz, K; Urban, P; Wysocka, M

2017-11-01

Liquid scintillation counting (LSC) is a measuring technique, broadly applied in environmental monitoring of radionuclides. One of the possible applications of LSC is the measurement of radon and thoron decay products. But this method is suitable only for grab sampling. For long-term measurements a different technique can be applied-monitors of potential alpha energy concentration (PAEC) with thermoluminescent detectors (TLD). In these devices, called Alfa-2000 sampling probe, TL detectors (CaSO4:Dy) are applied for alpha particles counting. Three independent heads are placed over the membrane filter in a dust sampler's microcyclone. Such solution enables simultaneous measurements of PAEC and dust content. Moreover, the information which is stored in TLD chips is the energy of alpha particles, not the number of counted particles. Therefore, the readout of TL detector shows directly potential alpha energy, with no dependence on equilibrium factor, etc. This technique, which had been used only for radon decay products measurements, was modified by author to allow simultaneous measurements of radon and thoron PAEC. The LSC method can be used for calibration of portable radon decay products monitors. The LSC method has the advantage to be an absolute one, the TLD method to measure directly the (dose relevant) deposited energy. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A study of the polyethylene membrane used in diffusion chambers for radon gas concentration measurements

NASA Astrophysics Data System (ADS)

Leung, S. Y. Y.; Nikezic, D.; Leung, J. K. C.; Yu, K. N.

2007-10-01

Solid-state nuclear track detectors (SSNTDs) in diffusion chambers have been routinely used for long-term measurements of radon gas concentrations. In usual practice, a filter is added across the top of the diffusion chamber to stop the progeny from entering. Thoron can also be deterred from entering the diffusion chamber by using a polyethylene (PE) membrane. However, the thickness of the PE membrane is rarely specified in the literature. In this paper, we will present our experimental results for a radon exposure that the number of alpha-particle tracks registered by the LR 115 SSNTD in a Karlsruhe diffusion chamber covered with one layer of PE membrane is actually enhanced. This is explained by enhanced deposition of radon progeny on the outside surface of the PE membrane and the insufficient thickness of the PE membrane to stop the alpha particles emitted from these deposited radon progeny to reach the SSNTD. We will present the PE thickness which can stop the alpha particles emitted from the deposited radon or thoron progeny. For the "twin diffusion chambers method", one of the diffusion chambers is covered with PE membranes. The optimal number of thickness of PE membranes will be determined, which allows the largest amount of radon gas to diffuse into the diffusion chamber while at the same time screening out the largest amount of thoron gas.

Thoron Mitigation System based on charcoal bed for applications in thorium fuel cycle facilities (part 2): Development, characterization, and performance evaluation.

PubMed

Sudeep Kumara, K; Sahoo, B K; Gaware, J J; Sapra, B K; Mayya, Y S; Karunakara, N

2017-06-01

Exposure due to thoron ( 220 Rn) gas and its decay products in a thorium fuel cycle facility handling thorium or 232 U/ 233 U mixture compounds is an important issue of radiological concern requiring control and mitigation. Adsorption in a flow-through charcoal bed offers an excellent method of alleviating the release of 220 Rn into occupational and public domain. In this paper, we present the design, development, and characterization of a Thoron Mitigation System (TMS) for industrial application. Systematic experiments were conducted in the TMS for examining the 220 Rn mitigation characteristics with respect to a host of parameters such as flow rate, pressure drop, charcoal grain size, charcoal mass and bed depth, water content, and heat of the carrier gas. An analysis of the experimental data shows that 220 Rn attenuation in a flow through charcoal bed is not exponential with respect to the residence time, L/U a (L: bed depth; U a : superficial velocity), but follows a power law behaviour, which can be attributed to the occurrence of large voids due to wall channeling in a flow through bed. The study demonstrates the regeneration of charcoal adsorption capacity degraded due to moisture adsorption, by hot air blowing technique. It is found that the mitigation factor (MF), which is the ratio of the inlet 220 Rn concentration (C in ) to the outlet 220 Rn concentration (C out ), of more than 10 4 for the TMS is easily achievable during continuous operation (>1000 h) at a flow rate of 40 L min -1 with negligible (<1 cm of water column) pressure drop. The Thoron Mitigation System based on adsorption on charcoal bed offers a compact and effective device to remove 220 Rn from affluent air streams in a space constrained domain. The prototype system has been installed in a thorium fuel cycle facility where it is being evaluated for its long-term performance and overall effectiveness in mitigating 220 Rn levels in the workplace. Copyright © 2017 Elsevier Ltd. All rights reserved.

Instrument performance of a radon measuring system with the alpha-track detection technique.

PubMed

Tokonami, S; Zhuo, W; Ryuo, H; Yonehara, H; Yamada, Y; Shimo, M

2003-01-01

An instrument performance test has been carried out for a radon measuring system made in Hungary. The system measures radon using the alpha-track detection technique. It consists of three parts: the passive detector, the etching unit and the evaluation unit. A CR-39 detector is used as the radiation detector. Alpha-track reading and data analysis are carried out after chemical etching. The following subjects were examined in the present study: (1) radon sensitivity, (2) performance of etching and evaluation processes and (3) thoron sensitivity. The radon sensitivity of 6.9 x 10(-4) mm(-2) (Bq m(-3) d)(-1) was acceptable for practical application. The thoron sensitivity was estimated to be as low as 3.3 x 10(-5) mm(-2) (Bq m(-3) d)(-1) from the experimental study.

Preliminary Work Toward a Transuranic Activity Estimation Method for Rapid Discrimination of Anthropogenic from Transuranic Activity in Alpha Air Samples

DOE PAGES

Cope, S. Joseph; Hayes, Robert B.

2018-03-01

Radon ( 222Rn) and thoron ( 220Rn) progeny (primarily bismuth and polonium) are known interferents when rapid evaluation of transuranic content on air filters is of interest. These complexities stem from the overlapping energies of the progeny alpha particles onto the transuranic region of interest (3–5.5 MeV) where naturally-occurring alpha emitters can overwhelm the spectra. Due to the immediacy of the alpha counting methods employed, coupled with the half-life of thoron progeny dominated by 212Pb (t 1/2=10.6 h), a conservative transuranic activity estimate with rigorous uncertainty is being sought. A successful transuranic activity estimation method will incorporate any thoron progenymore » present on the filter providing 95% confidence decision levels in which a filter may be evaluated for emergency response applications. Twenty-three pairs of samples of various duration having no transuranic content were taken over a 2-mo period. The resulting filters were counted in a time series before non-linear least squares decay curve fitting was applied to the decay profile. For the samples considered, a transuranic activity estima-tor decision level was determined at 0.2 Bq for the given geographic location and months analyzed. In conclusion, validation of this method for other seasonal and geographic regions could provide enhanced emergency response capability when the presence of transuranic activity is suspected.« less

Preliminary Work Toward a Transuranic Activity Estimation Method for Rapid Discrimination of Anthropogenic from Transuranic Activity in Alpha Air Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cope, S. Joseph; Hayes, Robert B.

Radon ( 222Rn) and thoron ( 220Rn) progeny (primarily bismuth and polonium) are known interferents when rapid evaluation of transuranic content on air filters is of interest. These complexities stem from the overlapping energies of the progeny alpha particles onto the transuranic region of interest (3–5.5 MeV) where naturally-occurring alpha emitters can overwhelm the spectra. Due to the immediacy of the alpha counting methods employed, coupled with the half-life of thoron progeny dominated by 212Pb (t 1/2=10.6 h), a conservative transuranic activity estimate with rigorous uncertainty is being sought. A successful transuranic activity estimation method will incorporate any thoron progenymore » present on the filter providing 95% confidence decision levels in which a filter may be evaluated for emergency response applications. Twenty-three pairs of samples of various duration having no transuranic content were taken over a 2-mo period. The resulting filters were counted in a time series before non-linear least squares decay curve fitting was applied to the decay profile. For the samples considered, a transuranic activity estima-tor decision level was determined at 0.2 Bq for the given geographic location and months analyzed. In conclusion, validation of this method for other seasonal and geographic regions could provide enhanced emergency response capability when the presence of transuranic activity is suspected.« less

Thoron, radon and air ions spatial distribution in indoor air.

PubMed

Kolarž, Predrag; Vaupotič, Janja; Kobal, Ivan; Ujić, Predrag; Stojanovska, Zdenka; Žunić, Zora S

2017-07-01

Spatial distribution of radioactive gasses thoron (Tn) and radon (Rn) in indoor air of 9 houses mostly during winter period of 2013 has been studied. According to properties of alpha decay of both elements, air ionization was also measured. Simultaneous continual measurements using three Rn/Tn and three air-ion active instruments deployed on to three different distances from the wall surface have shown various outcomes. It has turned out that Tn and air ions concentrations decrease with the distance increase, while Rn remained uniformly distributed. Exponential fittings function for Tn variation with distance was used for the diffusion length and constant as well as the exhalation rate determination. The obtained values were similar with experimental data reported in the literature. Concentrations of air ions were found to be in relation with Rn and obvious, but to a lesser extent, with Tn. Copyright © 2016 Elsevier Ltd. All rights reserved.

A new method for evaluating radon and thoron alpha-activities per unit volume inside and outside various natural material samples by calculating SSNTD detection efficiencies for the emitted alpha-particles and measuring the resulting track densities.

PubMed

Misdaq, M A; Aitnouh, F; Khajmi, H; Ezzahery, H; Berrazzouk, S

2001-08-01

A Monte Carlo computer code for determining detection efficiencies of the CR-39 and LR-115 II solid-state nuclear track detectors (SSNTD) for alpha-particles emitted by the uranium and thorium series inside different natural material samples was developed. The influence of the alpha-particle initial energy on the SSNTD detection efficiencies was investigated. Radon (222Rn) and thoron (220Rn) alpha-activities per unit volume were evaluated inside and outside the natural material samples by exploiting data obtained for the detection efficiencies of the SSNTD utilized for the emitted alpha-particles, and measuring the resulting track densities. Results obtained were compared to those obtained by other methods. Radon emanation coefficients have been determined for some of the considered material samples.

Observations and modelling of thoron and its progeny in the soil-atmosphere-plant system.

PubMed

Baldacci, A E; Gattavecchia, E; Kirchner, G

2010-11-01

Samples of pasture vegetation, mainly Trifolium pratensis, were collected at the Botanic Garden of the University of Bologna during the period 1998-2000 and measured by gamma-spectrometry for determining thoron progeny. Concentrations of (212)Pb were between 1.5 and 20 Bq m(-2), with individual peaks up to 70 Bq m(-2). Soil samples were collected at the same location and physically characterised. Their chemical composition (particularly Th and U) was determined by X-ray fluorescence spectroscopy. Lead-212 on plants mainly originates from dry and wet deposition of this isotope generated in the lower atmosphere by the decay of its short-lived precursor (220)Rn, which is produced in the upper soil layers as a member of the natural thorium decay chain and exhales into the atmosphere. Concentrations of (220)Rn in the atmosphere depend on (1) the amount of Th present in soil, (2) the radon fraction which escapes from the soil minerals into the soil pore space, (3) its transport into the atmosphere, and (4) its redistribution within the atmosphere. The mobility of radon in soil pore space can vary by orders of magnitude depending on the soil water content, thus being the main factor for varying concentrations of (220)Rn and (212)Pb in the atmosphere. We present a simple model to predict concentrations of thoron in air and its progeny deposited from the atmosphere, which takes into account varying soil moisture contents calculated by the OPUS code. Results of this model show close agreement with our observations.

Thoron Mitigation System based on charcoal bed for applications in thorium fuel cycle facilities (part 1): Development of theoretical models for design considerations.

PubMed

Sahoo, B K; Sudeep Kumara, K; Karunakara, N; Gaware, J J; Sapra, B K; Mayya, Y S

2017-06-01

Regulating the environmental discharge of 220 Rn (historically known as thoron) and its decay products from thorium processing facilities is important for protection of environment and general public living in the vicinities. Activated charcoal provides an effective solution to this problem because of its high adsorption capacity to gaseous element like radon. In order to design and develop a charcoal based Thoron Mitigation System, a mathematical model has been developed in the present work for studying the 220 Rn transport and adsorption in a flow through charcoal bed and estimating the 220 Rn mitigation factor (MF) as a function of system and operating parameters. The model accounts for inter- and intra-grain diffusion, advection, radioactive decay and adsorption processes. Also, the effects of large void fluctuation and wall channeling on the mitigation factor have been included through a statistical model. Closed form solution has been provided for the MF in terms of adsorption coefficient, system dimensions, grain size, flow rate and void fluctuation exponent. It is shown that the delay effects due to intra grain diffusion plays a significant role thereby rendering external equilibrium assumptions unsuitable. Also, the application of the statistical model clearly demonstrates the transition from the exponential MF to a power-law form and shows how the occurrence of channels with low probability can lower mitigation factor by several orders of magnitude. As a part of aiding design, the model is further extended to optimise the bed dimensions in respect of pressure drop and MF. The application of the results for the design and development of a practically useful charcoal bed is discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Variation in the radon concentrations and outdoor gamma radiation levels in relation to different geological formations in the thermal regions of Bursa, Turkey.

PubMed

Akkaya, Gizem; Kahraman, Ayşegül; Koray, Abdullah; Kaynak, Gökay

2016-09-01

Spring waters used as spas and their region may contain significant amounts of natural radionuclides. The main sources of exposure are the inhalation of radon and its decay products released from the water and soil and terrestrial gamma-radiation. In order to evaluate the potential risk of thermal regions in Bursa, located in the impact area of the NAF (North Anatolian Fault), radon and thoron concentrations in soil gas, radon concentrations in thermal waters and outdoor gamma radiation levels were measured in thermal regions that have different geological formations. The radon and thoron concentrations in soil-gas were found to vary from 2272  ±  121 to 245196  ±  3455 Bq m -3 and from 999  ±  218 to 178 848  ±  17 742 Bq m -3 , respectively. The radon concentrations in thermal waters ranged from 0.99  ±  0.21 to 226.74  ±  2.51 Bq l -1 in the rainy season and from 0.26  ±  0.10 to 178.03  ±  12.86 Bq l -1 in the dry season. The measured outdoor gamma radiation levels varied from 38 to 180 nGy h -1 . The gamma dose rates were found to be strong positively correlating with the radon and thoron concentrations in soil-gas. The radon and outdoor gamma radiation levels were observed to be a function of the geological formations of the area.

INNOVATIVE EASY-TO-USE PASSIVE TECHNIQUE FOR 222RN AND 220RN DECAY PRODUCT DETECTION.

PubMed

Mishra, Rosaline; Rout, R; Prajith, R; Jalalluddin, S; Sapra, B K; Mayya, Y S

2016-10-01

The decay products of radon and thoron are essentially the radioisotopes of polonium, bismuth and lead, and are solid particulates, which deposit in different parts of the respiratory tract upon inhalation, subsequently emitting high-energy alpha particles upon their radioactive decay. Development of passive deposition-based direct progeny sensors known as direct radon and thoron progeny sensors have provided an easy-to-use technique for time-integrated measurements of the decay products only. These dosemeters are apt for large-scale population dosimetry to assign inhalation doses to the public. The paper gives an insight into the technique, the calibration, comparison with the prevalently used active grab filter paper sampling technique, alpha track diameter analysis in these progeny sensors, progeny deposition velocity measurements carried out using these detector systems in the indoor as well as outdoor environment, and applications of these sensors for time-integrated unattached fraction estimation. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

MEASUREMENT OF RADON CONCENTRATION IN DWELLINGS IN THE REGION OF HIGHEST LUNG CANCER INCIDENCE IN INDIA.

PubMed

Zoliana, B; Rohmingliana, P C; Sahoo, B K; Mishra, R; Mayya, Y S

2016-10-01

Indoor radon/thoron concentration has been measured in Aizawl district, Mizoram, India, which has the highest lung cancer incidence rates among males and females in India. Simultaneously, radon flux emanated from the surrounding soil of the dwellings was observed in selected places. The annual average value of concentration of radon(thoron) of Aizawl district is 48.8(22.65) Bq m -3 with a geometric standard deviation of 1.25(1.58). Measured radon flux from the soil has an average value of 22.6 mBq m -2 s -1 These results were found to be much below the harmful effect or action level as indicated by the World Health Organisation. On the other hand, food habit and high-level consumption of tobacco and its products in the district have been found to increase the risk of lung cancer incidence in the district. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Radon and Thoron Measured in Petrol and Gas-oil Exhaust Fumes by Using CR-39 and LR-115 II Nuclear Track Detectors: Radiation Doses to the Respiratory Tract of Mechanic Workers.

PubMed

Misdaq, M A; Chaouqi, A; Ouguidi, J; Touti, R; Mortassim, A

2015-06-01

Mechanic workers are exposed to exhaust fumes when controlling vehicle engines in motion inside repair shops. To assess radiation doses due to radon short-lived progeny from the inhalation of exhaust fumes by mechanic workers, concentrations of these radionuclides were measured in petrol (gasoline) and gas-oil exhaust fumes by evaluating mean critical angles of etching of the CR-39 and LR-115 type II SSNTDs for alpha particles emitted by the radon and thoron decay series. Committed effective doses due to ²¹⁸Po and ²¹⁴Po short-lived radon decay products from the inhalation of petrol and gas-oil exhaust fumes by workers were evaluated. A maximum value of 1.35 mSv y⁻¹ due to radon short-lived decay products from the inhalation of gas-oil exhaust fumes by mechanic workers was found, which is lower than the (3-10 mSv y⁻¹) dose limit interval for workers.

A radon-thoron isotope pair as a reliable earthquake precursor

PubMed Central

Hwa Oh, Yong; Kim, Guebuem

2015-01-01

Abnormal increases in radon (222Rn, half-life = 3.82 days) activity have occasionally been observed in underground environments before major earthquakes. However, 222Rn alone could not be used to forecast earthquakes since it can also be increased due to diffusive inputs over its lifetime. Here, we show that a very short-lived isotope, thoron (220Rn, half-life = 55.6 s; mean life = 80 s), in a cave can record earthquake signals without interference from other environmental effects. We monitored 220Rn together with 222Rn in air of a limestone-cave in Korea for one year. Unusually large 220Rn peaks were observed only in February 2011, preceding the 2011 M9.0 Tohoku-Oki Earthquake, Japan, while large 222Rn peaks were observed in both February 2011 and the summer. Based on our analyses, we suggest that the anomalous peaks of 222Rn and 220Rn activities observed in February were precursory signals related to the Tohoku-Oki Earthquake. Thus, the 220Rn-222Rn combined isotope pair method can present new opportunities for earthquake forecasting if the technique is extensively employed in earthquake monitoring networks around the world. PMID:26269105

RADIATION EXPOSURE OF THE POPULATION FROM 222Rn AND OTHER NATURAL RADIONUCLIDES AROUND MOCHOVCE NUCLEAR POWER PLANT, SLOVAKIA.

PubMed

Bulko, Martin; Holý, Karol; Pohronská, Žofia; Mullerová, Monika; Böhm, Radoslav; Holá, Ol'ga

2017-11-01

In this article, the effective dose to the population from natural sources of ionizing radiation in the vicinity of Mochovce nuclear power plant in Slovakia is presented. All major contributions to the effective dose were taken into account, including the contributions from gamma radiation of soil and rocks, cosmic radiation, and indoor and outdoor radon and thoron. On the basis of recent indoor radon measurements in Slovak cities and publicly available data about radon concentration in the soil air, a roughly linear relationship was found between these variables. Consequently, the annual effective dose from indoor radon and thoron was conservatively estimated. For the area of interest, a map of conservatively estimated potential effective doses was created. For the villages in the vicinity of Mochovce, the conservatively estimated effective dose to the population from natural sources ranged from 5.4 to 14.6 mSv, which is four orders of magnitude higher than the contribution of radioactive discharges from Mochovce nuclear power plant. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A method of discriminating transuranic radionuclides from radon progeny using low-resolution alpha spectroscopy and curve-fitting techniques.

PubMed

Konzen, Kevin; Brey, Richard

2012-05-01

²²²Rn (radon) and ²²⁰Rn (thoron) progeny are known to interfere with determining the presence of long-lived transuranic radionuclides, such as plutonium and americium, and require from several hours up to several days for conclusive results. Methods are proposed that should expedite the analysis of air samples for determining the amount of transuranic radionuclides present using low-resolution alpha spectroscopy systems available from typical alpha continuous air monitors (CAMs) with multi-channel analyzer (MCA) capabilities. An alpha spectra simulation program was developed in Microsoft Excel visual basic that employed the use of Monte Carlo numerical methods and serial-decay differential equations that resembled actual spectra. Transuranic radionuclides were able to be quantified with statistical certainty by applying peak fitting equations using the method of least squares. Initial favorable results were achieved when samples containing radon progeny were decayed 15 to 30 min, and samples containing both radon and thoron progeny were decayed at least 60 min. The effort indicates that timely decisions can be made when determining transuranic activity using available alpha CAMs with alpha spectroscopy capabilities for counting retrospective air samples if accompanied by analyses that consider the characteristics of serial decay.

Attached and unattached fractions of short-lived radon decay products in outdoor environments: effect on the human respiratory system.

PubMed

Amrane, M; Oufni, L; Misdaq, M A

2014-12-01

The authors developed a model for determining the alpha- and beta-activities per unit volume of air due to radon ((222)Rn), thoron ((220)Rn) and their decay products attached and unattached to the aerosol in the outdoor air at the workplace in natural conditions at different locations in Morocco by using both CR-39 and LR-115 type II solid-state nuclear track detectors. In addition, the percentage of (218)Po, (214)Pb and (214)Po radionuclides attached to the aerosols and the unattached fraction f(j) for different values of the attachment rate were evaluated. Radon and thoron concentrations in outdoor air of the studied different locations were found to vary from 9.20±0.8 to 16.30±1.50 Bq m(-3) and 0.22±0.02 to 1.80±0.20 Bq m(-3), respectively. The committed equivalent doses due to the radon short-lived progeny (218)Po and (214)Po attached and unattached to the aerosol air were evaluated in different tissues of the respiratory tract of the members of the public from the inhalation of outdoor air. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Laboratory Directed Research and Development Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

Laboratory Directed Research and Development Program. Annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

An intercomparison for NIRS and NYU passive thoron gas detectors at NYU.

PubMed

Sorimachi, Atsuyuki; Ishikawa, Tetsuo; Tokonami, Shinji; Chittaporn, Passaporn; Harley, Naomi H

2012-04-01

An intercomparison on thoron ((220)Rn) measurement was carried out between National Institute of Radiological Sciences, Japan (NIRS), and New York University School of Medicine, USA (NYU). The measurements of (220)Rn concentration at NIRS and NYU were performed by using the scintillation cell method and the two-filter method, respectively, as the standard measurement method. Three types of alpha track detectors based on passive radon ((222)Rn)-(220)Rn discriminative measurement technique were used: Raduet and Radopot detectors were used at NIRS, and four-leaf detectors were used at NYU. In this study, the authors evaluated (220)Rn concentration variation in terms of run for exposure, measurement method, and exposure chamber. The detectors were exposed to (220)Rn gas with approximately 15 kBq m(-3) during the period from 0.75 to 3 d. As a result, the variation of each measurement method among these exposure runs was comparable to or less than that for the two-filter method. Agreement between the standard measurement methods of NIRS and NYU was observed to be about 10%, as is the case with the passive detectors. The Raduet detector showed a large variation in the detection response between the NIRS and NYU chambers, which could be related to different traceability.

Orphan radon daughters at Denver Radium site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holub, R.F.; Droullard, R.F.; Davis, T.H.

During 18 mo of sampling airborne radioactively at a National Priority List ({open_quotes}Superfund{close_quotes}) site in metroPOlitan Denver, Bureau of mines personnel discovered radon daughters that are not supported by the parent radon gas. We refer to them as {open_quotes}orphan{close_quotes} daughters because the parent, radon, is not present in sufficient concentration to support the measured daughter products. Measurements of the {open_quotes}orphan{close_quotes} daughters were made continuously, using the Bureau-developed radon and working-level (radon-daughter) monitors. The data showed high equilibrium ratios, ranging from 0.7 to 3.5, for long periods of time. Repeated, high-volume, 15-min grab samples were made, using the modified Tsivoglou method,more » to measure radon daughters, to which thoron daughters contributed 26 {+-} 12%. On average 28 {+-} 6% of the particulate activity was contributed by thoron daughters. Most samples were mixtures in which the {sup 218}Po concentration was lower than that of {sup 214}Pb and {sup 214}Bi, in agreement with the high-equilibrium factors obtained from the continuous sampling data. In view of the short half-life of radon progeny, we conclude that the source of the orphan daughters is not far from the Superfund sites. The mechanism of this phenomenon is not understood at this time, but we will discuss its possible significance in evaluating population doses.« less

Critical level setting of continuous air monitor.

PubMed

Li, Huibin; Jia, Mingyan; Wang, Kailiang

2013-01-01

Algorithms used to compensate the radon and thoron progeny's interference are one of the key technologies for continuous air monitors (CAMs). In this study, a CAM that can automatically change filter was manufactured, and equations used to calculate the transuranic aerosol concentration and the corresponding critical level were derived. The parameters used in calculation were acquired by continuous measurement in a high radon environment. At last, validation of the calculation was tested in a cave where the radon concentration fluctuated frequently, and the results were analysed.

Measurement of (222)Rn by absorption in plastic scintillators and alpha/beta pulse shape discrimination.

PubMed

Mitev, Krasimir K

2016-04-01

This work demonstrates that common plastic scintillators like BC-400, EJ-200 and SCSF-81 absorb radon and their scintillation pulse decay times are different for alpha- and beta-particles. This allows the application of pulse shape analysis for separation of the pulses of alpha- and beta-particles emitted by the absorbed radon and its progeny. It is shown that after pulse shape discrimination of beta-particles' pulses, the energy resolution of BC-400 and EJ-200 alpha spectra is sufficient to separate the peaks of (222)Rn, (218)Po and (214)Po and allows (222)Rn measurements that are unaffected by the presence of thoron ((220)Rn) in the environment. The alpha energy resolution of SCSF-81 in the experiments degrades due to imperfect collection of the light emitted inside the scintillating fibers. The experiments with plastic scintillation microspheres (PSM) confirm previous findings of other researchers that PSM have alpha-/beta-discrimination properties and show suitability for radon measurements. The diffusion length of radon in BC-400 and EJ-200 is determined. The pilot experiments show that the plastic scintillators are suitable for radon-in-soil-gas measurements. Overall, the results of this work suggest that it is possible to develop a new type of radon measurement instruments which employ absorption in plastic scintillators, pulse-shape discrimination and analysis of the alpha spectra. Such instruments can be very compact and can perform continuous, real-time radon measurements and thoron detection. They can find applications in various fields from radiation protection to earth sciences. Copyright © 2016 Elsevier Ltd. All rights reserved.

Inhalation exposures due to radon and thoron ((222)Rn and (220)Rn): Do they differ in high and normal background radiation areas in India?

PubMed

Mishra, Rosaline; Sapra, B K; Prajith, R; Rout, R P; Jalaluddin, S; Mayya, Y S

2015-09-01

In India, High Background Radiation Areas (HBRAs) due to enhanced levels of naturally occurring radionuclides in soil (thorium and, to a lesser extent, uranium), are located along some parts of the coastal tracts viz. the coastal belt of Kerala, Tamilnadu and Odisha. It is conjectured that these deposits will result in higher emissions of radon isotopes ((222)Rn and (220)Rn) and their daughter products as compared to Normal Background Radiation Areas (NBRAs). While the annual external dose rates contributed by gamma radiations in these areas are about 5-10 times higher, the extent of increase in the inhalation dose rates attributable to (222)Rn and (220)Rn and their decay products is not well quantified. Towards this, systematic indoor surveys were conducted wherein simultaneous measurements of time integrated (222)Rn and (220)Rn gas and their decay product concentrations was carried out in around 800 houses in the HBRAs of Kerala and Odisha to estimate the inhalation doses. All gas measurements were carried out using pin-hole cup dosimeters while the progeny measurements were with samplers and systems based on the Direct radon/thoron Progeny sensors (DRPS/DTPS). To corroborate these passive measurements of decay products concentrations, active sampling was also carried out in a few houses. The results of the surveys provide a strong evidence to conclude that the inhalation doses due to (222)Rn and (220)Rn gas and their decay products in these HBRAs are in the same range as observed in the NBRAs in India. Copyright © 2015 Elsevier Ltd. All rights reserved.

Intrinsic backgrounds from Rn and Kr in the XENON100 experiment

NASA Astrophysics Data System (ADS)

Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; Di Gangi, P.; Di Giovanni, A.; Diglio, S.; Eurin, G.; Fei, J.; Ferella, A. D.; Fieguth, A.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Itay, R.; Kaminsky, B.; Kazama, S.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Lin, Q.; Lindemann, S.; Lindner, M.; Lombardi, F.; Lopes, J. A. M.; Manfredini, A.; Maris, I.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Messina, M.; Micheneau, K.; Molinario, A.; Morå, K.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Piro, M.-C.; Pizzella, V.; Plante, G.; Priel, N.; Ramírez García, D.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rupp, N.; dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Lavina, L. Scotto; Selvi, M.; Shagin, P.; Silva, M.; Simgen, H.; Sivers, M. Von; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C.; Vargas, M.; Wang, H.; Wang, Z.; Weber, M.; Wei, Y.; Weinheimer, C.; Wittweg, C.; Wulf, J.; Ye, J.; Zhang, Y.

2018-02-01

In this paper, we describe the XENON100 data analyses used to assess the target-intrinsic background sources radon (?), thoron (?) and krypton (?). We detail the event selections of high-energy alpha particles and decay-specific delayed coincidences. We derive distributions of the individual radionuclides inside the detector and quantify their abundances during the main three science runs of the experiment over a period of ˜ 4 years, from January 2010 to January 2014. We compare our results to external measurements of radon emanation and krypton concentrations where we find good agreement. We report an observed reduction in concentrations of radon daughters that we attribute to the plating-out of charged ions on the negatively biased cathode.

Dosimetric assessment from 212Pb inhalation at a thorium purification plant.

PubMed

Campos, M P; Pecequilo, B R S

2004-01-01

At the Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, Brazil, there is a facility (thorium purification plant) where materials with high thorium concentrations are manipulated. In order to estimate afterwards the lung cancer risk for the workers, the thoron daughter (212Pb) levels were assessed and the committed effective and lung committed equivalent doses for workers in place. A total of 28 air filter samples were measured by total alpha counting through the modified Kusnetz method, to determine the 212Pb concentraion. The committed effective dose and lung committed equivalent dose due to 212Pb inhalation were derived from compartmental analysis following the ICRP 66 lung compartmental model, and ICRP 67 lead metabolic model.

The University of Rochester Atomic Energy Project quarterly report, April 1, 1950--June 30, 1950

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blair, H.A.

This quarterly progress report gives an overview of the University of Rochester Atomic Energy Project for April 1, 1950 thru June 30, 1950. Sections included are entitled (1) Biological Effects of External Radiation (X-rays and gamma rays), (2) Biological Effects of External Radiation (Infra-red and ultraviolet), (3) Biological effects of radioactive materials (polonium, radon, thoron, and miscellaneous project materials), (4) Uranium, (5) Beryllium, (7) thorium, (8) fluoride, (9) zirconium, (10) special materials, (11) Isotopes, (12) Outside services, (12) Project health, (13) Health physics, (14) Special Clinical Service, and (15) Instrumentation (Spectroscopy, electron microscopy, x-ray and nuclear radiation detectors, x-ray diffraction,more » and electronics).« less

Natural radioactivity content in soil and indoor air of Chellanam.

PubMed

Mathew, S; Rajagopalan, M; Abraham, J P; Balakrishnan, D; Umadevi, A G

2012-11-01

Contribution of terrestrial radiation due to the presence of naturally occurring radionuclides in soil and air constitutes a significant component of the background radiation exposure to the population. The concentrations of natural radionuclides in the soil and indoor air of Chellanam were investigated with an aim of evaluating the environmental radioactivity level and radiation hazard to the population. Chellanam is in the suburbs of Cochin, with the Arabian Sea in the west and the Cochin backwaters in the east. Chellanam is situated at ∼25 km from the sites of these factories. The data obtained serve as a reference in documenting changes to the environmental radioactivity due to technical activities. Soil samples were collected from 30 locations of the study area. The activity concentrations of (232)Th, (238)U and (40)K in the samples were analysed using gamma spectrometry. The gamma dose rates were calculated using conversion factors recommended by UNSCEAR [United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. UNSCEAR (2000)]. The ambient radiation exposure rates measured in the area ranged from 74 to 195 nGy h(-1) with a mean value of 131 nGy h(-1). The significant radionuclides being (232)Th, (238)U and (40)K, their activities were used to arrive at the absorbed gamma dose rate with a mean value of 131 nGy h(-1) and the radium equivalent activity with a mean value of 162 Bq kg(-1). The radon progeny levels varied from 0.21 to 1.4 mWL with a mean value of 0.6 mWL. The thoron progeny varied from 0.34 to 2.9 mWL with a mean value of 0.85 mWL. The ratio between thoron and radon progenies varied from 1.4 to 2.3 with a mean of 1.6. The details of the study, analysis and results are discussed.

Evaluation of radon adsorption characteristics of a coconut shell-based activated charcoal system for radon and thoron removal applications.

PubMed

Karunakara, N; Sudeep Kumara, K; Yashodhara, I; Sahoo, B K; Gaware, J J; Sapra, B K; Mayya, Y S

2015-04-01

Radon ((222)Rn), thoron ((220)Rn), and their decay products contribute a major fraction (more than 50%) of doses received from ionisation radiation in public domain indoor environments and occupation environments such as uranium mines, thorium plants, and underground facilities, and are recognised as important radiological hazardous materials, which need to be controlled. This paper presents studies on the removal of (222)Rn and (220)Rn from air using coconut shell-based granular activated charcoal cylindrical adsorber beds. Experiments were conducted to evaluate the (222)Rn and (220)Rn adsorption characteristics, and the mitigation efficiency of coconut-based activated charcoal available in India. The performance parameters evaluated include breakthrough time (τ) and adsorption coefficient (K), and degassing characteristics of the charcoal bed of varying dimensions at different flow rates. While the breakthrough for (222)Rn occurred depending on the dimension of the adsorber bed and flow rates, for (220)Rn, the breakthrough did not occur. The breakthrough curve exhibited a stretched S-shape response, instead of the theoretically predicted sharp step function. The experiments confirm that the breakthrough time individually satisfies the quadratic relationship with respect to the diameter of the bed, and the linear relationship with respect to the length, as predicted in the theory. The K value varied in the range of 2.3-4.12 m(3) kg(-1) with a mean value of 2.99 m(3) kg(-1). The K value was found to increase with the increase in flow rate. Heating the charcoal to ∼ 100 °C resulted in degassing of the adsorbed (222)Rn, and the K of the degassed charcoal and virgin charcoal were found to be similar with no deterioration in performance indicating the re-usability of the charcoal. Copyright © 2015 Elsevier Ltd. All rights reserved.

Horizonal and Vertical Spatial Patterns of Radon and Other Soil-gases Across the El Pilar Fault Trace at Guaraphiche, Edo. Surce (Venezuela)

NASA Astrophysics Data System (ADS)

LaBrecque, J. J.

2002-05-01

Soil-gases (radon, thoron, carbon dioxide and hydrogen) were measured at 63-cm depths along a transect perpendicular to the rupture (fault trace) from the 1997 Caricao earthquake (Mw=6.9) at Guarapiche, state of Sucre (Venezuela). The transect was about 40 meters long with ten sampling points with the spacings was smaller near the rupture. The shapes of the horizontal spatial patterns for radon (Rn-222), thoron (Rn-220) and total radon (Rn-222+Rn-220) were similar; the gas concentrations increased from both ends of the transect toward the rupture where a dip (valley) occurred. Both carbon dioxide and hydrogen gases showed anomalous values at the same sampling points. Twin peaks (anomalies) had been previously reported and suggested that they were due to blockage in the rupture. We have also determined soil-gases from 25-cm to 155-cm depths near the rupture and at the ends of the transect. The results showed that the soil-gas concentrations were not only higher in the upper levels (less than 65-cm) near the fault trace but were similar or greater than the lower levels. Thus, producing the twin peaks when soil-gas sampling was performed at the 65-cm depth. When the sampling was performed at only 45-cm depth the dip over the rupture was much less and the patterns looked more like a broad doublet peak. In conclusion, one can clearly see that not only positive soil-gas anomalies can occur over a fault trace but also negative ones too. 1) This work was partially funded by a research contract from the Venezuelan National Science Foundation (CONICIT Proyecto S1-95000448). 2) Mailing Address: Centro de Quimica, 8424 NW 56th Street, Suite 00204,Miami, Fl 33166 (USA). E-mail jjlabrec@ivic.ve FAX: +58-212-504-1214

Radon isotope measurements as a monitoring tool for CO2 leakage in geological storage

NASA Astrophysics Data System (ADS)

Grandia, F.; Mazadiego, L. F.; de Elío, J.; Ortega, M.; Bruno, J.

2011-12-01

Early detection of the failure of the seal integrity is fundamental in the monitoring plan of a deep geological CO2 storage. A number of methods of leakage control are based on changes in fluid geochemistry (shallow water, soil gases) providing valuable indicators. Among them, the measurement of CO2 fluxes in the soil-atmosphere interface is commonly used since it can be easily done using portable infra-red analyzers (i.e., accumulation chambers). However, initial emission of CO2 from storage horizon could be masked by fluxes from biological activity, limiting its applicability as an early alarm system. The measurement of fluxes of trace gas (Rn, He, VOC) that are virtually absent in the pre-injection baseline turns out a promising complementary method. The measurement of radon isotopes has been long used for the observation of mass transport from deep reservoirs to surface despite the flux of 222Rn and 220Rn is usually very limited in sedimentary basins due to the short half-life of these isotopes. The enhanced transport of radon in CO2 fluxes has been reported from natural systems, resulting in concentration in air up to several thousands of Bq/m3. In the frame of the Compostilla pilot plant project in Spain, a number of methodologies to measure radon emission are being tested in natural systems to select of the most reliable and cost-effective method to be used in leakage control. These methods are (1) Scintillation detector EDA RD-200, (2) Track Etch °, (3) Ionization Chamber and (4) alpha spectroscopy SARAD RTM 200. Some of them are capable of measuring the isotopes separately (SARAD) whereas others just detect the bulk radon concentration. Also, these methods follow distinct procedures and acquisition times. The studied natural sites are located in central and NE Spain (Campo de Calatrava and La Selva basins), and in central Italy (Arezzo basin). Apparently, radon isotopes (up 200000 Bq/m3) are measured far from parent isotopes, and they are coupled to moderate to high CO2 fluxes (from 1×10-7 to 5×10-5 kg/m-2/s), along with other minor and trace gases (H2S, VOC, helium). The results in some sites show that not all Rn isotopes behave in the same way. In some cases, thoron (220Rn) does not flow with CO2 and 222Rn and, consequently, it appears to be a need to use methods capable of discriminating isotopes to avoid masking of unbounded radon to CO2 flux. The highest radon-thoron ratio is then related to CO2 flow. The behavior of radon isotopes could be caused by different rocks at depth. In addition, travel time for thoron could be too long compared to its very short half life (few hours). The methods tested provide similar radon data although some of them need further data refinement. SARAD alpha spectroscopy appears to be effective in the sites studied so far, which are characterized by high radon fluxes. Future work in the project is the testing of these techniques in areas with smaller radon fluxes and the determination of the gases that may interact with radon in some methods.

Thoron (220Rn) in the indoor environment and work places

NASA Astrophysics Data System (ADS)

Ramachandran, T. V.; Sahoo, B. K.

2009-08-01

Ever since studies on uranium miners established the presence of a positive risk coefficient for the occurrence of lung cancer in miners exposed to elevated levels of 222Rn and its progeny, there was a great upsurge of interest in the measurement of 222Rn in the environment. Subsequently, considerable data is being generated on the levels of 222Rn in the environment across the worlds and is being periodically reported by UNSCEAR reports. In contrast to this, data pertaining to 220Rn in indoors and workplace environment is scaree due to the genral perception that its levels are negligible due to its shorter half life, and subsequently its contribution to the total inhalation dose is ignored, in the presence of other significant sources of natural radiation. This may not be true. Globally many locations have higher levels of natural background radiation due to elevated levels of primordial radio nuclides in the soil and their decay products like radon (222Rn), and thoron (220Rn) in the environment. Of late, technologically enhanced naturally occurring radioactive material has also contributed to the burden of background radiation. It is estimated that inhalation of 222Rn, 220Rn and their short lived progenies contribute more than 54% of the total natural background radiation dose received by the general population. 220Rn problem exists in industries which use thorium nitrate. Including India, lamps using thoriated gas mantles are still being used for indoor and outdoor lighting and by hawkers in rural as well as urban areas. Considering the fact that large amount of thorium nitrate is being handled by these industries, contribution to the inhalation dose of workers from 220Rn gas emanated and build up of the progeny in ambient air may also be quite significant. In this paper current status of 220Rn levels in the indoor environment and workplaces as well as in other industries where large amount of 232Th is being handled is being summarized. Methods of measurement and reported levels are also summarized.

Thoron concentration, aerosol characteristics of 212Pb and estimation of equivalent dose

NASA Astrophysics Data System (ADS)

Mohery, M.; Abdallah, A. M.; Kelany, Adel M.; Yaghmour, S. J.

2014-08-01

The thoron gas (220Rn) activity concentration as well as activity size distribution of unattached and attached 212Pb to aerosol particles was measured in the open air of Jeddah City, Kingdom of Saudi Arabia. An electroprecipitation method was applied for measuring the 220Rn concentration. A mean activity concentration of 220Rn was determined to be 1.80±0.47 Bq m-3. The unattached activities of 212Pb were collected using the wire screen diffusion battery technique while a low-pressure cascade impactor collected the attached activities. The mean activity median thermodynamic diameter (AMTD) of unattached 212Pb was determined to be 1.32 nm with a relative mean geometric standard deviation (σg) of 1.45. A mean concentration of unattached activity of 212Pb was found to be 9.48±1.12 mBq m-3. A mean unattached fraction (fp) of 0.028±0.002 was obtained at a mean aerosol particle concentration of 29×103 cm-3. Sometimes, the fp values were less than the detection limit of 0.009. A mean activity median aerodynamic diameter (AMAD) of the accumulation mode of attached 212Pb was determined to be 352 nm with a mean (σg) of 2.6. The mean value of specific air activity concentration of 212Pb associated with that mode was determined to be 310±12 mBq m-3. With a dosimetric model calculation (ICRP, 1994) the total and regional deposition fractions, total and regional equivalent doses could be evaluated considering the obtained parameters of the activity size distributions. At a total deposition fraction of about 97% of unattached activities the total equivalent dose to the human lung was determined to be 0.16 μSv while a total equivalent dose of 0.44 μSv was determined at a total deposition fraction of about 23% for the attached activities. It was found that an unattached fraction of fP≈3% yields to about 27% of the total equivalent dose.

Determination of small and large amounts of fluorine in rocks

USGS Publications Warehouse

Grimaldi, F.S.; Ingram, B.; Cuttitta, F.

1955-01-01

Gelatinous silica and aluminum ions retard the distillation of fluorine in the Willard and Winter distillation method. A generally applicable, simple method for the determination of fluorine in rocks containing aluminum or silicon or both as major constituents was desired. In the procedure developed, the sample is fused with a mixture of sodium carbonate and zinc oxide, leached with water, and filtered. The residue is granular and retains nearly all of the silica. The fluorine in the filtrate is distilled directly from a perchloric acid-phosphoric acid mixture. Phosphoric acid permits the quantitative distillation of fluorine in the presence of much aluminum at the usual distillation temperature and without the collection of large volumes of distillate. The fluorine is determined either by microtitration with thorium nitrate or colorimetrically with thoron. The procedure is rapid and has yielded excellent results on silicate rocks and on samples from the aluminum phosphate (leached) zone of the Florida phosphate deposits.

Performance of the first Japanese large-scale facility for radon inhalation experiments with small animals.

PubMed

Ishimori, Yuu; Mitsunobu, Fumihiro; Yamaoka, Kiyonori; Tanaka, Hiroshi; Kataoka, Takahiro; Sakoda, Akihiro

2011-07-01

A radon test facility for small animals was developed in order to increase the statistical validity of differences of the biological response in various radon environments. This paper illustrates the performances of that facility, the first large-scale facility of its kind in Japan. The facility has a capability to conduct approximately 150 mouse-scale tests at the same time. The apparatus for exposing small animals to radon has six animal chamber groups with five independent cages each. Different radon concentrations in each animal chamber group are available. Because the first target of this study is to examine the in vivo behaviour of radon and its effects, the major functions to control radon and to eliminate thoron were examined experimentally. Additionally, radon progeny concentrations and their particle size distributions in the cages were also examined experimentally to be considered in future projects.

High time-resolved radon progeny measurements in the Arctic region (Svalbard islands, Norway): results and potentialities

NASA Astrophysics Data System (ADS)

Salzano, Roberto; Pasini, Antonello; Ianniello, Antonietta; Mazzola, Mauro; Traversi, Rita; Udisti, Roberto

2018-05-01

The estimation of radon progeny in the Arctic region represents a scientific challenge due to the required low limit of detection in consideration of the limited radon emanation associated with permafrost dynamics. This preliminary study highlighted, for the first time above 70° N, the possibility to monitor radon progeny in the Arctic region with a higher time resolution. The composition of the radon progeny offered the opportunity to identify air masses dominated by long-range transport, in presence or absence of near-constant radon progeny instead of long- and short-lived progenies. Furthermore, the different ratio between radon and thoron progenies evidenced the contributions of local emissions and atmospheric stability. Two different emanation periods were defined in accordance with the permafrost dynamics at the ground and several accumulation windows were recognized coherently to the meteo-climatic conditions occurring at the study site.

Estimation of attached and unattached progeny of 222Rn and 220Rn concentration using deposition based progeny sensors.

PubMed

Mehra, Rohit; Bangotra, Pargin; Kaur, Kirandeep; Kanse, Sandeep; Mishra, Rosaline

2015-11-01

The attached and unattached radon and thoron progeny concentrations have been calculated using deposition-based progeny sensors in Mansa, Muktsar, Bathinda and Faridkot districts of Punjab, India. The total (attached + unattached) equilibrium-equivalent (222)Rn concentration (EECRA + U) and total (attached + unattached) equilibrium-equivalent (220)Rn concentration (EECTA + U) were found to vary from 9 to 46 Bqm(-3) and 0.5 to 3.1 Bq m(-3), respectively. The concentrations of attached progeny nuclides for both (222)Rn and (220)Rn have been found to be greater than the unattached progeny nuclides in the dwellings of studied area. An attempt has also been made to assess the effective dose for (222)Rn and (220)Rn in the studied area. The radiation dose originated from (222)Rn and (220)Rn progeny is low and health risk is negligible. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

EML indoor radon workshop, 1982

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, A.C.; Lowder, W.; Fisenne, I.

1983-07-01

A workshop on indoor radon, held at the Environmental Measurements Laboratory (EML) on November 30 and December 1, 1982, covered recent developments in radon daughter research and development. Thirty papers were presented dealing with standardization and quality assurance measurement methods, surveys, measurements strategy, physical mechanisms of radon and radon daughter transport and development of guidance standards for indoor exposures. The workshop concluded with a planning session that identified the following needs: (1) national and international intercomparisons of techniques for measuring radon and radon daughter concentrations, working level and radon exhalation flux density; (2) development and refinement of practical measurement techniquesmore » for thoron and its daughter products; (3) quantitative definition of the sources of indoor radon and the mechanisms of transport into structures; (4) better knowledge of the physical properties of radon daughters; (5) more complete and accurate data on the population exposure to radon, which can only be met by broadly based surveys; and (6) more international cooperation and information exchange among countries with major research programs.« less

The Effect of CO 2 on the Measurement of 220Rn and 222Rn with Instruments Utilising Electrostatic Precipitation

DOE PAGES

Lane-Smith, Derek; Sims, Kenneth

2013-06-09

In some volcanic systems, thoron and radon activity and CO 2 flux, in soil and fumaroles, show a relationship between ( 220Rn/ 222Rn) and CO 2 efflux. It is theorized that deep, magmatic sources of gas are characterized by high 222Rn activity and high CO 2 efflux, whereas shallow sources are indicated by high 220Rn activity and relatively low CO 2 efflux. In this paper we evaluate whether the observed inverse relationship is a true geochemical signal, or potentially an analytical artifact of high CO 2 concentrations. We report results from a laboratory experiment using the RAD7 radon detector, knownmore » 222Rn (radon) and 220Rn (thorn), and a controllable percentage of CO 2 in the carrier gas. Our results show that for every percentage of CO 2, the 220Rn reading should be multiplied by 1.019, the 222Rn radon should be multiplied by 1.003 and the 220Rn/ 222Rn ratio should be multiplied by 1.016 to correct for the presence of the CO 2.« less

A continuous sampler with background suppression for monitoring alpha-emitting aerosol particles.

PubMed

McFarland, A R; Rodgers, J C; Ortiz, C A; Moore, M E

1992-05-01

A continuous air monitor has been developed that includes provisions for improving the detection of alpha-emitting aerosol particles in the presence of radon/thoron progeny that are unattached to ambient aerosol particles. Wind tunnel tests show that 80% of 10-microns aerodynamic equivalent diameter particles penetrate the flow system from the ambient air to the collection filter when the flow rate is 57 L min-1 (2 cfm) and the wind speed is 1 m s-1. Uniformity of aerosol collection on the filter, as characterized by the coefficient of variation of the areal density deposits, is less than 15% for 10-microns aerodynamic-equivalent-diameter aerosol particles. Tests with unattached radon daughters in a flow-through chamber showed that approximately 99% of the 218Po was removed by an inlet screen that is designed to collect radon daughters that are in the size range of molecular clusters. The inlet screen offers the opportunity to improve the signal-to-noise ratio of energy spectra in the regions of interest (subranges of the energy spectrum) of transuranic elements and thereby enhance the performance of background compensation algorithms.

Environmental Measurements Laboratory 1994 annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chieco, N.A.; Krey, P.W.; Beck, H.L.

1995-08-01

This report summarizes the activities of the Environmental Measurements Laboratory (EML) for the calendar year 1994 and it serves as an annual report to the Director of the Office of Energy Research (ER), the Associate Director and staff of the Office of Health and Environmental Research (OHER), the manager and staff of the Chicago Field Office, and the authors colleagues. Emphasized are the progress and accomplishments of the year, rather than future plans or expectations. The technical summaries are grouped according to the following seven general program areas: environmental radiation and radioactivity; radiation transport and dosimetry; environmental radon, thoron, andmore » related aerosols; atmospheric and surface pollutant studies related to global climate change; atmospheric chemistry; metrology, consultation, and emergency response; environmental management. EML`s mission is to address important scientific questions concerning human health and environmental impacts. Through its multidisciplinary staff, EML conducts experimental and theoretical research on radioactive and other energy-related pollutants, and provides DOE and other federal agencies with the in-house capability to respond effectively and efficiently with regard to quality assurance activities, environmental issues and related national security issues.« less

The Effect of CO 2 on the Measurement of 220Rn and 222Rn with Instruments Utilising Electrostatic Precipitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lane-Smith, Derek; Sims, Kenneth

In some volcanic systems, thoron and radon activity and CO 2 flux, in soil and fumaroles, show a relationship between ( 220Rn/ 222Rn) and CO 2 efflux. It is theorized that deep, magmatic sources of gas are characterized by high 222Rn activity and high CO 2 efflux, whereas shallow sources are indicated by high 220Rn activity and relatively low CO 2 efflux. In this paper we evaluate whether the observed inverse relationship is a true geochemical signal, or potentially an analytical artifact of high CO 2 concentrations. We report results from a laboratory experiment using the RAD7 radon detector, knownmore » 222Rn (radon) and 220Rn (thorn), and a controllable percentage of CO 2 in the carrier gas. Our results show that for every percentage of CO 2, the 220Rn reading should be multiplied by 1.019, the 222Rn radon should be multiplied by 1.003 and the 220Rn/ 222Rn ratio should be multiplied by 1.016 to correct for the presence of the CO 2.« less

THE NRPI MULTI-PURPOSE ON-LINE MONITORING STATION FOR MEASUREMENT OF NATURAL RADIOACTIVITY IN THE AMBIENT ATMOSPHERE AND IN THE SOIL.

PubMed

Jílek, K; Slezáková, M; Fronka, A; Prokop, T; Neubauer, L

2017-11-01

During years 2010-12 an automated, on-line and wireless outdoor measurement station of atmospheric radon, gamma dose rate and meteorological parameters was realised at the National Radiation Protection Institute (NRPI) in Prague. At the turn of the year 2013 an expansion of the existing station was completed. Under the project funded by the Czech Technological Agency a new updated station was established, additionally equipped with modules for measurement of atmospheric radon/thoron short-lived decay products, radon in water and soil and radon exhalation rate from soil. After the introduction of the station updated key detection parameters and benefits, its use for atmospheric modelling and monitoring is demonstrated. There are summarised results from the 3-year measurement period in the NRPI outdoor area in Prague and from simultaneous annual measurement performed by another similar station located near uranium mud fields in DIAMO, state enterprise, Stráž pod Ralskem. Observed seasonal and diurnal variations of atmospheric radon concentrations and variability of the equilibrium factor, F, are illustrated and compared. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

NIOSH comments to DOL on MSHA's advance notice of proposed rulemaking (ANPR) metal and nonmetal mine safety and health, radiation standards by J. D. Millar, March 18, 1985

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1985-03-18

The testimony presents the views of NIOSH with regard to specific issues raised by MSHA in a proposed rulemaking affecting metal and nonmetal mine safety and health, radiation standards. Results are included from epidemiological studies in which the relationship between lung cancer and exposure to radon daughters was examined. A quantitative risk assessment is also noted which will be considered in the development of a NIOSH recommended exposure limit for radon daughters. Specific issues addressed include risk assessment, particularly the relationship and the associated uncertainty between cumulative lifetime radon daughters exposure at or below 120 working level months and themore » lifetime risk of lung cancer or other biological response, and themethodology used to arrive at the risk relationship. The use of a nonthreshold model extrapolating from elevated exposure levels is considered along with modification of the risk relationship to account for cell repair or other factors. Questions concerning the latency period, cigarette smoking, exposure to thoron daughters, exposure to gamma radiation, and exposure to ore dusts are also addressed.« less

Composition of Radioactive Aerosols in the Shelter Construction of the Chernobyl Nuclear Power Plant in 2000-2015

NASA Astrophysics Data System (ADS)

Ogorodnikov, B. I.

2018-06-01

The results of the physicochemical studies of radioactive aerosols inside and outside the Shelter construction at the Arch construction stage of the Chernobyl Nuclear Power Plant (ChNPP) in 2000-2015 were presented. The dominant isotopes were shown to be cesium, strontium, americium, plutonium, and uranium. They are carried by disperse particles of 2-7 μm. In subreactor rooms, in particular, 012/7, the composition of aerosols is affected by the erosion of the fuel-containing mass formed in 1986. Submicron cesium carrier aerosols appear as a result of evaporation and condensation during fires and welding works. Radiocesium is a well-soluble component of aerosols, while plutonium isotopes are not readily soluble components. In several rooms, the contents of radon, thoron, and their daughter products exceeded the permissible values. In April-June 2011, the intake of radionuclides from the accident at the Japanese Fukushima-1 NPP, which had AMAD of 0.5 μm, was detected and tracked using Petryanov multilayer filters. The productivity of filtration units under the dusty conditions in the exclusion zone of ChNPP and in fogs and haze was investigated. Hydrophilic prefilters with 7-10 μm fibers were recommended.

Radon dose assessment in underground mines in Brazil.

PubMed

Santos, T O; Rocha, Z; Cruz, P; Gouvea, V A; Siqueira, J B; Oliveira, A H

2014-07-01

Underground miners are internally exposed to radon, thoron and their short-lived decay products during the mineral processing. There is also an external exposure due to the gamma emitters present in the rock and dust of the mine. However, the short-lived radon decay products are recognised as the main radiation health risk. When inhaled, they are deposited in the respiratory system and may cause lung cancer. To address this concern, concentration measurements of radon and its progeny were performed, the equilibrium factor was determined and the effective dose received was estimated in six Brazilian underground mines. The radon concentration was measured by using E-PERM, AlphaGUARD and CR-39 detectors. The radon progeny was determined by using DOSEman. The annual effective dose for the miners was estimated according to United Nations Scientific Committee on the Effects of Atomic Radiation methodologies. The mean value of the equilibrium factor was 0.4. The workers' estimated effective dose ranged from 1 to 21 mSv a(-1) (mean 9 mSv a(-1)). © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Environmental Measurements Laboratory, annual report 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krey, P.W.; Heit, M.

1996-07-01

This report summarizes the activities of the Environmental Measurements Laboratory (EML) for the calendar year 1995 and serves as an annual report to the Director of the Office of Energy Research (ER), the Associate Director and staff of the Office of Health and Environmental Research (OHER), the Manager and staff of the Chicago Operations Office, and our colleagues. Emphasized are the progress and accomplishments of the year, rather than future plans or expectations. The technical summaries are grouped according to the following seven research program areas: (1) Environmental Radiation and Radioactivity; (2) Radiation Transport and Dosimetry; (3) Environmental Radon, Thoron,more » and Related Aerosols; (4) Atmospheric and Surface Pollutant Studies Related to Global Climate Change; (5) Atmospheric Chemistry; and (6) Metrology, Consultation, and Emergency Response Environmental Management The mission of EML is to address important scientific questions concerning human health and environmental impacts. Through its multidisciplinary staff, EML conducts experimental and theoretical research on radioactive and other energy-related pollutants and provides DOE and other federal agencies with the in-house capability to respond effectively and efficiently with regard to quality assurance activities, environmental issues, and related national security issues.« less

Use of natural radionuclides to determine the time range of the accidental melting of an orphan radioactive source in a steel recycling plant.

PubMed

Cantaluppi, Chiara; Ceccotto, Federica; Cianchi, Aldo

2012-02-01

In the rare event that an orphan radioactive source is melted in an Electric Arc Furnace steel recycling plant, the radionuclides present are partitioned in the different products, by-products and waste. As a consequence of an unforeseen melting of a radiocesium source, cesium radioisotopes can be found in the dust, together with many natural radionuclides from the decay of radon and thoron, which are present in the atmosphere, picked up from the off-gas evacuation system and associated with the dust of the air filtration system ("baghouse"). In this work we verified that the activity concentration of ²¹²Pb in this dust is essentially constant in a specific factory so that it is possible to use it to date back to the time of the accidental melting of the orphan radioactive source. The main features of this method are described below, together with the application to a particular case in which this method was used for dating the moment in which the dust was contaminated with ¹³⁷Cs. Copyright © 2011 Elsevier Ltd. All rights reserved.

Estimation of the indoor radon and the annual effective dose from granite samples

NASA Astrophysics Data System (ADS)

Sola, P.; Srinuttrakul, W.; Kewsuwan, P.

2015-05-01

Inhalation of radon and thoron daughters increases the risk of lung cancer. The main sources of indoor radon are building materials. The aim of this research is to estimate the indoor radon and the annual effective dose from the building materials. Eighteen granite samples bought from the markets in Thailand were measured using an ionization chamber (ATMOS 12 DPX) for the radon concentration in air. Radon exhalation rates were calculated from the radon concentration in chamber. The indoor radon from the granite samples ranged from 10.04 to 55.32 Bq·m-2·h-1 with an average value of 20.30 Bq·m-2·h-1 and the annual effective dose ranged from 0.25 to 1.39 mSv·y-1 with an average value of 0.48 mSv·y-1. The results showed that the annual effective doses of three granite samples were higher than the annual exposure limit for the general public (1 mSv·y-1) recommended by the International Commission on Radiological Protection (ICRP). In addition, the relationship between the colours and radon exhalation rates of granite samples was also explained.

Maywood Interim Storage Site annual environmental report for calendar year 1991, Maywood, New Jersey. Formerly Utilized Sites Remedial Action Program (FUSRAP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-09-01

This document describes the environmental monitoring program at the Maywood Interim Storage Site (MISS) and surrounding area, implementation of the program, and monitoring results for 1991. Environmental monitoring of MISS began in 1984 when congress added the site to the US Department of Energy`s (DOE) Formerly Utilized Sites Remedial Action Program (FUSRAP). FUSRAP is a DOE program to identify and decontaminate or otherwise control sites where residual radioactive materials remain from the early years of the nation`s atomic energy program or from commercial operations causing conditions that Congress has authorized DOE to remedy. The environmental monitoring program at MISS includesmore » sampling networks for radon and thoron concentrations in air; external gamma radiation-exposure; and total uranium, radium-226, radium-228, thorium-232, and thorium-230 concentrations in surface water, sediment, and groundwater. Additionally, several nonradiological parameters are measured in surface water, sediment, and groundwater. Monitoring results are compared with applicable Environmental Protection Agency standards, DOE derived concentration guides (DCGs), dose limits, and other requirements in DOE orders. Environmental standards are established to protect public health and the environment.« less

Maywood Interim Storage Site annual environmental report for calendar year 1991, Maywood, New Jersey. [Maywood Interim Storage Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1992-09-01

This document describes the environmental monitoring program at the Maywood Interim Storage Site (MISS) and surrounding area, implementation of the program, and monitoring results for 1991. Environmental monitoring of MISS began in 1984 when congress added the site to the US Department of Energy's (DOE) Formerly Utilized Sites Remedial Action Program (FUSRAP). FUSRAP is a DOE program to identify and decontaminate or otherwise control sites where residual radioactive materials remain from the early years of the nation's atomic energy program or from commercial operations causing conditions that Congress has authorized DOE to remedy. The environmental monitoring program at MISS includesmore » sampling networks for radon and thoron concentrations in air; external gamma radiation-exposure; and total uranium, radium-226, radium-228, thorium-232, and thorium-230 concentrations in surface water, sediment, and groundwater. Additionally, several nonradiological parameters are measured in surface water, sediment, and groundwater. Monitoring results are compared with applicable Environmental Protection Agency standards, DOE derived concentration guides (DCGs), dose limits, and other requirements in DOE orders. Environmental standards are established to protect public health and the environment.« less

Characterization of radon levels in soil and groundwater in the North Maladeta Fault area (Central Pyrenees) and their effects on indoor radon concentration in a thermal spa.

PubMed

Moreno, V; Bach, J; Zarroca, M; Font, Ll; Roqué, C; Linares, R

2018-09-01

Radon levels in the soil and groundwater in the North Maladeta Fault area (located in the Aran Valley sector, Central Pyrenees) are analysed from both geological and radiation protection perspectives. This area is characterized by the presence of two important normal faults: the North Maladeta fault (NMF) and the Tredós Fault (TF). Two primary aspects make this study interesting: (i) the NMF shows geomorphic evidence of neotectonic activity and (ii) the presence of a thermal spa, Banhs de Tredós, which exploits one of the several natural springs of the area and needs to be evaluated for radiation dosing from radon according to the European regulation on basic safety standards for protection against ionizing radiation. The average soil radon and thoron concentrations along a profile perpendicular to the two normal faults - 22 ± 3 kBq·m -3 and 34 ± 3 kBq·m -3 , respectively - are not high and can be compared to the radionuclide content of the granitic rocks of the area, 25 ± 4 Bq·kg -1 for 226 Ra and 38 ± 2 Bq·kg -1 for 224 Ra. However, the hypothesis that the normal faults are still active is supported by the presence of anomalies in both the soil radon and thoron levels that are unlikely to be of local origin together with the presence of similar anomalies in CO 2 fluxes and the fact that the highest groundwater radon values are located close to the normal faults. Additionally, groundwater 222 Rn data have complemented the hydrochemistry data, enabling researchers to better distinguish between water pathways in the granitic and non-granitic aquifers. Indoor radon levels in the spa vary within a wide range, [7-1664] Bq·m -3 because the groundwater used in the treatment rooms is the primary source of radon in the air. Tap water radon levels inside the spa present an average value of 50 ± 8 kBq·m -3 , which does not exceed the level stipulated by the Spanish Nuclear Safety Council (CSN) of 100 kBq·m -3 for water used for human consumption. This finding implies that even relatively low radon concentration values in water can constitute a relevant indoor radon source when the transfer from water to indoor air is efficient. The estimated effective dose range of values for a spa worker due to radon inhalation is [1-9] mSv·y -1 . The use of annual averaged radon concentration values may significantly underestimate the dose in these situations; therefore, a detailed dynamic study must be performed by considering the time that the workers spend in the spa. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhancement of radon exposure in smoking areas.

PubMed

Abdel Ghany, Hayam A

2007-06-01

Radium-226 is a significant source of radon-222 which enters buildings through soil, construction materials or water supply. When cigarette smoke is present, the radon daughters attach to smoke particles. Thus, the alpha radiation to a smoker's lungs from the natural radon daughters is increased because of smoking. To investigate whether the cigarette tobacco itself is a potential source of indoor radon, the alpha potential energy exposure level contents of radon ((222)Rn, 3.82d) and Thoron ((220)Rn, 55.60s) were measured in 10 different cigarette tobacco samples using CR-39 solid-state nuclear track detectors (SSNTDs). The results showed that the (222, 220)Rn concentrations in these samples ranged from 128 to 266 and 49 to 148 Bqm(-3), respectively. The radon concentrations emerged from all investigated samples were significantly higher than the background level. Also, the annual equivalent doses from the samples were determined. The mean values of the equivalent dose were 3.51 (0.89) and 1.44 (0.08) mSvy(-1), respectively. Measurement of the average indoor radon concentrations in 20 café rooms was, significantly, higher than 20 smoking-free residential houses. The result refers to the dual (chemical and radioactive) effect of smoking as a risk factor for lung cancer.

A newly validated and characterized spectrophotometric method for determination of a three water pollutants metal ions

NASA Astrophysics Data System (ADS)

Mohamed, Marwa E.; Frag, Eman Y. Z.; Mohamed, Mona A.

2018-01-01

A simple, fast and accurate spectrophotometric method had been developed to determine lead (II), chromium (III) and barium (II) ions in pure forms and in spiked water samples using thoron (THO) as a reagent forming colored complexes. It was found that the formed complexes absorbed maximally at 539, 540 and 538 nm for Pb(II)-THO, Cr(III)-THO and Ba(II)-THO complexes, respectively. The optimum experimental conditions for these complexes had been studied carefully. Beer's law was obeyed in the range 1-35, 1-70, and 1-45 μg mL- 1 for Pb (II), Cr(III) and Ba(II) ions with THO reagent, respectively. Different parameters such as linearity, selectivity, recovery, limits of quantification and detection, precision and accuracy were also evaluated in order to validate the proposed method. The results showed that, THO was effective in simultaneous determination of Pb(II), Cr(III) and Ba(III) ions in pure forms and in spiked water samples. Also, the results of the proposed method were compared with that obtained from atomic absorption spectrometry. The isolated solid complexes had been characterized using elemental analysis, X-ray powder diffraction (XRD), IR, mass spectrometry and TD-DFT calculations. Their biological activities were investigated against different types of bacteria and fungi organisms.

Measurement of 222Rn and 220Rn exhalation rate from soil samples of Kumaun Hills, India

NASA Astrophysics Data System (ADS)

Semwal, Poonam; Singh, Kuldeep; Agarwal, T. K.; Joshi, Manish; Pant, Preeti; Kandari, Tushar; Ramola, R. C.

2018-03-01

The source terms, i.e., exhalation and emanation from soil and building materials are the primary contributors to the radon (222Rn)/thoron (220Rn) concentration levels in the dwellings, while the ecological constraints like ventilation rate, temperature, pressure, humidity, etc., are the influencing factors. The present study is focused on Almora District of Kumaun, located in Himalayan belt of Uttarakhand, India. For the measurement of 222Rn and 220Rn exhalation rates, 24 soil samples were collected from different locations. Gamma radiation level was measured at each of these locations. Chamber technique associated with Smart Rn Duo portable monitor was employed for the estimation of 222Rn and 220Rn exhalation rates. Radionuclides (226Ra, 232Th and 40K) concentrations were also measured in soil samples using NaI(Tl) scintillation based gamma ray spectrometry. The mass exhalation rate for 222Rn was varying between 16 and 54 mBq/kg/h, while the 220Rn surface exhalation rate was in the range of 0.65-6.43 Bq/m2/s. Measured gamma dose rate for the same region varied from 0.10 to 0.31 µSv/h. Inter-correlation of exhalation rates and intra-correlation with background gamma levels were studied.

Reduction of airborne radioactive dust by means of a charged water spray.

PubMed

Bigu, J; Grenier, M G

1989-07-01

An electrostatic precipitator based on charged water spray technology has been used in an underground uranium mine to control long-lived radioactive dust and short-lived aerosol concentration in a mine gallery where dust from a rock breaking/ore transportation operation was discharged. Two main sampling stations were established: one upstream of the dust precipitator and one downstream. In addition, dust samplers were placed at different locations between the dust discharge and the end of the mine gallery. Long-lived radioactive dust was measured using cascade impactors and nylon cyclone dust samplers, and measurement of the radioactivity on the samples was carried out by conventional methods. Radon and thoron progeny were estimated using standard techniques. Experiments were conducted under a variety of airflow conditions. A maximum radioactive dust reduction of about 40% (approximately 20% caused by gravitational settling) at a ventilation rate of 0.61 m3/sec was obtained as a result of the combined action of water scrubbing and electrostatic precipitation by the charged water spray electrostatic precipitator. This represents the optimum efficiency attained within the range of ventilation rates investigated. The dust reduction efficiency of the charged water spray decreased with increasing ventilation rate, i.e., decreasing air residence time, and hence, reduced dust cloud/charged water droplets mixing time.

Controlling alpha tracks registration in Makrofol DE 1-1 detector

NASA Astrophysics Data System (ADS)

Hassan, N. M.; Hanafy, M. S.; Naguib, A.; El-Saftawy, A. A.

2017-09-01

Makrofol DE 1-1 is a recent type of solid state nuclear track detectors could be used to measure radon concentration in the environment throughout the detection of α-particles emitted from radon decay. Thus, studying the physical parameters that control the formation of alpha tracks is vital for environmental radiation protection. Makrofol DE 1-1 polycarbonate detector was irradiated by α-particles of energies varied from 2 to 5 MeV emitted from the 241Am source of α-particle energy of 5.5 MeV. Then, the detector was etched in an optimum etching solution of mixed ethyl alcohol in KOH aqueous solution of (85% (Vol.) of 6 M KOH + 15% (Vol.) C2H5OH) at 50 °C for 3 h. Afterward, the bulk etch rate, etching sensitivity, and the registration efficiency of the detector, which control the tracks registration, were measured. The bulk etch rate of Makrofol detector was found to be 3.71 ± 0.71 μm h-1. The etching sensitivity and the detector registration efficiency were decreased exponentially with α-particles' energies following Bragg curve. A precise registration of α-particle was presented in this study. Therefore, Makrofol DE 1-1 can be applied as a radiation dosimeter as well as radon and thoron monitors.

Observations of nearshore groundwater discharge: Kahekili Beach Park submarine springs, Maui, Hawaii

USGS Publications Warehouse

Swarzenski, Peter W.; Dulai, H.; Kroeger, K.D.; Smith, C.G.; Dimova, N.; Storlazzi, C. D.; Prouty, N.G.; Gingerich, S.B.; Glenn, C. R.

2016-01-01

Study regionThe study region encompasses the nearshore, coastal waters off west Maui, Hawaii. Here abundant groundwater—that carries with it a strong land-based fingerprint—discharges into the coastal waters and over a coral reef.Study focusCoastal groundwater discharge is a ubiquitous hydrologic feature that has been shown to impact nearshore ecosystems and material budgets. A unique combined geochemical tracer and oceanographic time-series study addressed rates and oceanic forcings of submarine groundwater discharge at a submarine spring site off west Maui, Hawaii.New hydrological insights for the regionEstimates of submarine groundwater discharge were derived for a primary vent site and surrounding coastal waters off west Maui, Hawaii using an excess 222Rn (t1/2 = 3.8 d) mass balance model. Such estimates were complemented with a novel thoron (220Rn,t1/2 = 56 s) groundwater discharge tracer application, as well as oceanographic time series and thermal infrared imagery analyses. In combination, this suite of techniques provides new insight into the connectivity of the coastal aquifer with the near-shore ocean and examines the physical drivers of submarine groundwater discharge. Lastly, submarine groundwater discharge derived constituent concentrations were tabulated and compared to surrounding seawater concentrations. Such work has implications for the management of coastal aquifers and downstream nearshore ecosystems that respond to sustained constituent loadings via this submarine route.

Radiological characterization of clay mixed red mud in particular as regards its leaching features.

PubMed

Hegedűs, Miklós; Sas, Zoltán; Tóth-Bodrogi, Edit; Szántó, Tamás; Somlai, János; Kovács, Tibor

2016-10-01

The reuse of industrial by-products such as red mud is of great importance. In the case of the building material industry the reuse of red mud requires a cautious attitude, since the enhanced radionuclide content of red mud can have an effect on human health. The natural radionuclide content of red mud from the Ajka red mud reservoir and the clay sample from a Hungarian brick factory were determined by gamma spectrometry. It was found that maximum 27.8% red mud content can be added to fulfil the conditions of the EU-BSS. The effect of heat treatment was investigated on a red mud-clay mixture and it was found that in the case of radon and thoron exhalation the applied heat reduced remarkably the exhalation capacities. The leaching features of red mud and different mixtures were studied according to the MSZ-21470-50 Hungarian standard, the British CEN/TS 14429 standard and the Tessier sequential extraction method. The Tessier method and the MSZ-21470-50 standard are suitable for the characterization of materials; however, they do not provide enough information for waste deposition purposes. To this end, we propose using the CEN/TS 14429 method, because it is easy to use, and gives detailed information about the material's behaviour under different pH conditions, however, further measurements are necessary. Copyright © 2016 Elsevier Ltd. All rights reserved.

Wayne Interim Storage Site environmental report for calendar year 1992, 868 Black Oak Ridge Road, Wayne, New Jersey. Formerly Utilized Sites Remedial Action Program (FUSRAP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-05-01

This report describes the environmental surveillance program at the Wayne Interim Storage Site (WISS) and provides the results for 1992. The fenced, site, 32 km (20 mi) northwest of Newark, New Jersey, was used between 1948 and 1971 for commercial processing of monazite sand to separate natural radioisotopes - predominantly thorium. Environmental surveillance of WISS began in 1984 in accordance with Department of Energy (DOE) Order 5400.1 when Congress added the site to DOE`s Formerly Utilized Sites Remedial Action Program (FUSRAP). The environmental surveillance program at WISS includes sampling networks for radon and thoron in air; external gamma radiation exposure;more » radium-226, radium-228, thorium-230, thorium-232, total uranium, and several chemicals in surface water and sediment; and total uranium, radium-226, radium-228, thorium-230, thorium-232, and organic and inorganic chemicals in groundwater. Monitoring results are compared with applicable Environmental Protection Agency (EPA) and state standards, DOE derived concentration guides (DCGs), dose limits, and other DOE requirements. This monitoring program assists in fulfilling the DOE policy of measuring and monitoring effluents from DOE activities and calculating hypothetical doses. Results for environmental surveillance in 1992 show that the concentrations of all radioactive and most chemical contaminants were below applicable standards.« less

Doses from beta radiation in sensitive layers of human lung and dose conversion factors due to 222Rn/220Rn progeny.

PubMed

Markovic, V M; Stevanovic, N; Nikezic, D

2011-08-01

Great deal of work has been devoted to determine doses from alpha particles emitted by (222)Rn and (220)Rn progeny. In contrast, contribution of beta particles to total dose has been neglected by most of the authors. The present work describes a study of the detriment of (222)Rn and (220)Rn progeny to the human lung due to beta particles. The dose conversion factor (DCF) was introduced to relate effective dose and exposure to radon progeny; it is defined as effective dose per unit exposure to inhaled radon or thoron progeny. Doses and DCFs were determined for beta radiation in sensitive layers of bronchi (BB) and bronchioles (bb), taking into account inhaled (222)Rn and (220)Rn progeny deposited in mucus and cilia layer. The nuclei columnar secretory and short basal cells were considered to be sensitive target layers. For dose calculation, electron-absorbed fractions (AFs) in the sensitive layers of the BB and bb regions were used. Activities in the fast and slow mucus of the BB and bb regions were obtained using the LUNGDOSE software developed earlier. Calculated DCFs due to beta radiation were 0.21 mSv/WLM for (222)Rn and 0.06 mSv/WLM for (220)Rn progeny. In addition, the influence of Jacobi room parameters on DCFs was investigated, and it was shown that DCFs vary with these parameters by up to 50%.

ASSESSMENT OF INHALATION DOSE FROM THE INDOOR 222Rn AND 220Rn USING RAD7 AND PINHOLE CUP DOSEMETERS.

PubMed

Mehra, R; Jakhu, R; Bangotra, P; Kaur, K; Mittal, H M

2016-10-01

Radon is the most important source of natural radiation and is responsible for approximately half of the received dose from all sources. Most of this dose is from inhalation of the radon progeny, especially in closed atmospheres. Concentration of radon ( 222 Rn) and thoron ( 220 Rn) in the different villages of Jalandhar and Kapurthala district of Punjab has been calculated by pinhole cup dosemeters and RAD7. On an average, it has been observed from the study that the values of all the parameters calculated are higher in case of active monitoring than the passive monitoring. The calculated equilibrium equivalent 222 Rn concentration (EEC Rn ) and equilibrium equivalent 220 Rn concentration (EEC Th ) fluctuate in the range from 5.58 to 34.29 and from 0.35 to 2.7 Bq m -3 as estimated by active technique, respectively. Similarly, the observed mean value of the potential alpha energy concentration of 222 Rn (PAEC Rn ) and 220 Rn (PAEC Th ) is 4.55 and 4.34 mWL, respectively. The dose rate to the soft tissues and lung from indoor 222 Rn varies from 0.06 to 0.38 and from 0.50 to 3.05 nGy h -1 , respectively. The total annual effective dose for the residents of the study area is less than 10 mSv. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A study on the correlation between soil radon potential and average indoor radon potential in Canadian cities.

PubMed

Chen, Jing; Ford, Ken L

2017-01-01

Exposure to indoor radon is identified as the main source of natural radiation exposure to the population. Since radon in homes originates mainly from soil gas radon, it is of public interest to study the correlation between radon in soil and radon indoors in different geographic locations. From 2007 to 2010, a total of 1070 sites were surveyed for soil gas radon and soil permeability. Among the sites surveyed, 430 sites were in 14 cities where indoor radon information is available from residential radon and thoron surveys conducted in recent years. It is observed that indoor radon potential (percentage of homes above 200 Bq m -3 ; range from 1.5% to 42%) correlates reasonably well with soil radon potential (SRP: an index proportional to soil gas radon concentration and soil permeability; average SRP ranged from 8 to 26). In five cities where in-situ soil permeability was measured at more than 20 sites, a strong correlation (R 2  = 0.68 for linear regression and R 2  = 0.81 for non-linear regression) was observed between indoor radon potential and soil radon potential. This summary report shows that soil gas radon measurement is a practical and useful predictor of indoor radon potential in a geographic area, and may be useful for making decisions around prioritizing activities to manage population exposure and future land-use planning. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture

DOEpatents

Lucas, Henry

1990-01-01

A method of and an apparatus for detecting and accurately measuring the mean concentrations of .sup.222 Rn and .sup.220 Tn in a gas mixture, such as the ambient atmosphere in a mine, is provided. The apparatus includes an alpha target member which defines at least one operative target surface and which is preferably fabricated from a single piece of an alpha particle sensitive material. At least one portion of the operative target surface is covered with an alpha particle filter. The uncovered and filter covered operative surface is exposed to the gas mixture containing the .sup.222 Rn and .sup.220 Tn. In the radioactive decay series of these isotopes the maximum kinetic energy emitted by the alpha decay of .sup.222 Rn is about 1.1 MeV less than the maximum kinetic energy emitted by the alpha decay of a .sup.220 Tn. The alpha particle filter has a predetermined mass per unit area of the covered portion of the operative target surface that prevents penetration of alpha particles which originate from .sup.222 Rn decay, but which allows passage therethrough of the maximum kinetic energy alpha particles from .sup.220 Tn decay. Thus, a count of the alpha particle tracks in the uncovered portion of the target member is proportional to the mean concentration of sum of .sup.222 Rn and .sup.220 Tn in the gas mixture, while the count of alpha tracks in the target member under the filter is proportional to the concentration of only the .sup.220 Tn in the gas mixture.

RADIATION HAZARD IN THE TREATMENT OF SKIN DISEASES WITH THORIUM X

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiskemann, A.; Janssen, U.

Possible hazards, particularly to the dermatologist and his assistants, in the use of local applications of thorium X (Ra/sup 224/) in salves and ointments for the treatment of skin diseases, such as psoriasis, nevus flammeus, and lichen ruber verrucosus, were assessed. The decay scheme of thorium X through its daughter products (thoron and thorium A, B, C, C', C", and D), the half lives of the products, and their emission characteristics are discussed. Studies in rats showed that topically applied ointment containing thorium X leads to measurable blood levels of radioactivity and deposition of daughter products in various tissues, includingmore » gonads. Radioautographs of rat lung and ovary demonstrated alpha -particle tracks in various tissue constituents. In humans receiving skin treatments with 1000 units thorium X (70 mu C/cm/sup 3/) the blood dose reached 2 rem, from which it was estimated that the whole-body dose would be approximates 3 rem/yr. In the treatment of a number of patients with a total of 30000 units thorium X, it was calculated that the whole-body to the person giving the treatment would be approximates 15 mr, although at chest level as much as 473 mr would be received. However, this is only 1/4 to 1/7 the permissible weekly gamma dose. Use of film dosimeters by persons applying treatments showed that the permissible dose was not being exceeded. Measurements of the radiation dose received by the personnel showed that it is mostly from inhalation of air in the treatment room. (TCO)« less

Annual committed effective dose from olive oil (due to 238U, 232Th, and 222Rn) estimated for members of the Moroccan public from ingestion and skin application.

PubMed

Misdaq, M A; Touti, R

2012-03-01

Olive oil is traditionally refined and widely consumed by Moroccan rural populations. Uranium (238U), thorium (232Th), radon (222Rn), and thoron (220Rn) contents were measured in various locally produced olive oil samples collected in rural areas of Morocco. These radionuclides were also measured inside various bottled virgin olive oils consumed by the Moroccan populations. CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs) were used. Annual committed effective doses due to 238U, 232Th, and 222Rn from the ingestion of olive oil by the members of the general public were determined. The maximum total committed effective dose due to 238U, 232Th, and 222Rn from the ingestion of olive oil by adult members of Moroccan rural populations was found equal to 5.9 µSv y-1. The influence of pollution due to building material dusts and phosphates on the radiation dose to workers from the ingestion of olive oil was investigated, and it was found that the maximum total committed effective dose due to 238U, 232Th, and 222Rn was on the order of 0.22 mSy y-1. Committed effective doses to skin due to 238U, 232Th, and 222Rn from the application of olive oil masks by rural women were evaluated. The maximum total committed effective dose to skin due to 238U, 232Th, and 222Rn was found equal to 0.07 mSy y-1 cm-2.

Outdoor 220Rn, 222Rn and terrestrial gamma radiation levels: investigation study in the thorium rich Fen Complex, Norway.

PubMed

Mrdakovic Popic, Jelena; Bhatt, Chhavi Raj; Salbu, Brit; Skipperud, Lindis

2012-01-01

The present study was done in the Fen Complex, a Norwegian area rich in naturally occurring radionuclides, especially in thorium ((232)Th). Measurement of radioactivity levels was conducted at the decommissioned iron (Fe) and niobium (Nb) mining sites (TENORM) as well as at the undisturbed wooded sites (NORM), all open for free public access. The soil activity concentrations of (232)Th (3280-8395 Bq kg(-1)) were significantly higher than the world and the Norwegian average values and exceeded the Norwegian screening level (1000 Bq kg(-1)) for radioactive waste, while radium ((226)Ra) was present at slightly elevated levels (89-171 Bq kg(-1)). Terrestrial gamma dose rates were also elevated, ranging 2.6-4.4 μGy h(-1). Based on long-term surveys, the air concentrations of thoron ((220)Rn) and radon ((222)Rn) reached 1786 and 82 Bq m(-3), respectively. Seasonal variation in the outdoor gamma dose rates and Rn concentrations was confirmed. Correlation analyses showed a linear relationship between air radiation levels and the abundance of (232)Th in soil. The annual outdoor effective radiation doses for humans (occupancy 5 h day(-1)) were estimated to be in the range of 3.0-7.7 mSv, comparable or higher than the total average (summarized indoor and outdoor) exposure dose for the Norwegian population (2.9 mSv year(-1)). On the basis of all obtained results, this Norwegian area should be considered as enhanced natural radiation area (ENRA).

A comparison of the dose from natural radionuclides and artificial radionuclides after the Fukushima nuclear accident

PubMed Central

Hosoda, Masahiro; Tokonami, Shinji; Omori, Yasutaka; Ishikawa, Tetsuo; Iwaoka, Kazuki

2016-01-01

Due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the evacuees from Namie Town still cannot reside in the town, and some continue to live in temporary housing units. In this study, the radon activity concentrations were measured at temporary housing facilities, apartments and detached houses in Fukushima Prefecture in order to estimate the annual internal exposure dose of residents. A passive radon–thoron monitor (using a CR-39) and a pulse-type ionization chamber were used to evaluate the radon activity concentration. The average radon activity concentrations at temporary housing units, including a medical clinic, apartments and detached houses, were 5, 7 and 9 Bq m−3, respectively. Assuming the residents lived in these facilities for one year, the average annual effective doses due to indoor radon in each housing type were evaluated as 0.18, 0.22 and 0.29 mSv, respectively. The average effective doses to all residents in Fukushima Prefecture due to natural and artificial sources were estimated using the results of the indoor radon measurements and published data. The average effective dose due to natural sources for the evacuees from Namie Town was estimated to be 1.9 mSv. In comparison, for the first year after the FDNPP accident, the average effective dose for the evacuees due to artificial sources from the accident was 5.0 mSv. Although residents' internal and external exposures due to natural radionuclides cannot be avoided, it might be possible to lower external exposure due to the artificial radionuclides by changing some behaviors of residents. PMID:26838130

Time dependence of 222Rn, 220Rn and their progenies' distributions in a diffusion chamber

NASA Astrophysics Data System (ADS)

Stevanovic, N.; Markovic, V. M.; Nikezic, D.

2017-11-01

Diffusion chamber with SSNTD (Solid State Nuclear Track Detector) placed inside is a passive detector for measuring the activity of 222Rn and 220Rn (radon and thoron) and their progenies. Calibration from detected alpha particle tracks to progeny activity is often acquired from theoretical models. One common assumption related to these models found in literature is that concentrations of 222Rn and 220Rn at the entrance of a chamber are constant during the exposure. In this paper, concentrations of 222Rn and 220Rn at the entrance of the chamber are taken to be variable with time, which is actually the case in reality. Therefore, spatial distributions of 222Rn and 220Rn and their progenies inside the diffusion chamber should be time dependent. Variation of 222Rn and 220Rn concentrations on the entrance of the chamber was modeled on the basis of true measurements. Diffusion equations in cylindrical coordinates were solved using FDM (Finite Difference Method) to obtain spatial distributions as functions of time. It was shown that concentrations of 222Rn, 220Rn and their progenies were not homogeneously distributed in the chamber. Due to variable 222Rn and 220Rn concentrations at the entrance of the chamber, steady state (the case when concentration of 222Rn, 220Rn and their progenies inside the chamber remains unchanged with time) could not be reached. Deposition of progenies on the chamber walls was considered and it was shown that distributions of deposited progenies were not uniform over walls' surface.

Maywood Interim Storage Site environmental report for calendar year 1992, 100 West Hunter Avenue, Maywood, New Jersey. Formerly Utilized Sites Remedial Action Program (FUSRAP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-05-01

This report describes the environmental surveillance program at the Maywood Interim Storage Site (MISS) and provides the results for 1992. Environmental monitoring of MISS began in 1984, when the site was assigned to DOE by Congress through the Energy and Water Development Appropriations Act and was placed under DOE`s Formerly Utilized Sites Remedial Action Program (FUSRAP). FUSRAP was established to identify and decontaminate or otherwise control sites where residual radioactive materials remain from the early years of the nation`s atomic energy program or from commercial operations causing conditions that Congress has authorized DOE to remedy. MISS is part of amore » National Priorities List (NPL) site. The environmental surveillance program at MISS includes sampling networks for radon and thoron in air; external gamma radiation exposure; and radium-226, radium-228, thorium-232, and total uranium in surface water, sediment, and groundwater. Additionally, chemical analysis includes metals and organic compounds in surface water and groundwater and metals in sediments. This program assists in fulfilling the DOE objective of measuring and monitoring effluents from DOE activities and calculating hypothetical doses to members of the general public. Monitoring results are compared with applicable Environmental Protection Agency (EPA) and state standards, DOE derived concentration guides (DCGs), dose limits, and other DOE requirements. Environmental standards are established to protect public health and the environment. The radiological data for all media sampled support the conclusion that doses to the public are not distinguishable from natural background radiation.« less

Radon and thoron in cave dwellings (Yan'an, China)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiegand, J.; Feige, S.; Xie Quingling

2000-04-01

{sup 222}Rn and {sup 220}Rn concentrations were measured in cave dwellings and brick houses in the region of Yan'an (China) during summer 1997. The underground dwellings are built into Quaternary loess, and all investigated houses are founded on it. The median values of indoor {sup 222}Rn and {sup 220}Rn concentrations are 42 (n = 18) and 77Bq m{sup {minus}3} (n = 15) for brick houses and 92 (n = 23) and 215 (n = 17) Bq m{sup {minus}3} for cave dwellings. To classify the dwellings in respect to their cave-character, the fraction of walls having a direct contact to themore » loess is calculated for each dwelling. While the {sup 222}Rn concentrations are increasing with higher fractions, the {sup 220}Rn concentrations are not correlated with this fraction. On the other hand, due to the short half-life of {sup 220}Rn the distance from the measuring point to the walls is negatively correlated with the {sup 220}Rn concentration, while there is no correlation with the {sup 222}Rn concentration. Therefore, concentric isolines of {sup 220}Rn concentrations showing a strong gradient were detected in cave dwellings. An influence of the ventilation rate is distinct for {sup 222}Rn but weak for {sup 220}Rn. The effective dose rates for {sup 222}Rn and {sup 220}Rn and their progenies are calculated for brick houses (2.7 mSv y{sup {minus}1}), cave dwellings (7.1 mSv y{sup {minus}1}), and for traditional cave dwellings with a bed foundation built with loess (16.7 mSv y{sup {minus}1}). These calculations are based on summer measurements only. It is expected that the true effective dose rates will be significantly higher.« less

Analysis of 238U, 232Th, 222Rn, and 220Rn in different medical drug preparations by using CR-39 and LR-115 typE II SSNTDs and resulting radiation doses to adult patients.

PubMed

Misdaq, M A; Karime, M

2009-01-01

Uranium (238U) and thorium (232Th) concentrations as well as radon (222Rn) and thoron (220Rn) alpha activities per unit volume have been measured inside 18 medical drugs (4 liquid and 14 solid materials), widely prescribed by doctors to the Moroccan adult patients, by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The measured 238U, 232Th, 222Rn, and 220Rn concentrations ranged from (4.7 +/- 0.1) mBq L-1 to (14.3 +/- 0.7) mBq L-1, (0.32 +/- 0.02) mBq L-1 to (2.7 +/- 0.2) mBq L-1, (4.7 +/- 0.2) Bq L-1 to (14.3 +/- 0.7) Bq L-1, and (0.32 +/- 0.02) Bq L-1 to (2.7 +/- 0.2) Bq L-1 for the medical drug samples studied, respectively. These radionuclides were also measured inside the preparations of the solid medical drugs studied. The influence of the drinking water nature and pollution on the concentrations of these radionuclides inside the considered medical drug preparations was investigated. Annual committed equivalent doses due to 238U, 232Th, and 222Rn were evaluated in the human body compartments of adult patients from the ingestion of the medical drug preparations studied. The maximum total committed effective dose due to 238U, 232Th, and 222Rn from the ingestion of the studied medical drug preparations, prepared from unpolluted waters, by adult patients was found equal to 1.44 microSv y.

Preliminary Experiments Using a Passive Detector for Measuring Indoor 220Rn Progeny Concentrations with an Aerosol Chamber.

PubMed

Sorimachi, Atsuyuki; Tokonami, Shinji; Kranrod, Chutima; Ishikawa, Tetsuo

2015-06-01

This paper describes preliminary experiments using a passive detector for integrating measurements of indoor thoron (²²⁰Rn) progeny concentrations with an aerosol chamber. A solid state nuclear detector (CR-39) covered with a thin aluminum-vaporized polyethylene plate (Mylar film) was used to detect only alpha particles emitted from ²¹²Po due to ²²⁰Rn progeny deposited on the detector surfaces. The initial experiment showed that Mylar film with area density of more than 5 mg cm⁻² was suitable to cut off completely alpha particles of 7.7 MeV from ²¹⁴Po of ²²²Rn progeny decay. In the experiment using the passive detector, it was observed that the net track density increased linearly with an increase of time-integrating ²²⁰Rn progeny concentration. As a result of dividing deposition rates by atom concentrations, the deposition velocity was given as 0.023 cm s⁻¹ for total ²²⁰Rn progeny. The model estimates of deposition velocities were 0.330 cm s⁻¹ for unattached ²²⁰Rn progeny and 0.0011 cm s⁻¹ for aerosol-attached ²²⁰Rn progeny using Lai-Nazaroff formulae. These deposition velocities were in the same range with the results reported in the literature. It was also found that the exposure experiments showed little influence of vertical profiles and surface orientations of the passive detector in the chamber on the detection responses, which was in good agreement with that in the model estimates. Furthermore, it was inferred that the main uncertainty of the passive detector was inhomogeneous deposition of Rn progeny onto its detection surfaces.

Radiological Monitoring of Waste Treatment Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amin, Y. M.; Nik, H. W.

2011-03-30

Scheduled waste in West Malaysia is handled by Concession Company and is stored and then is incinerated. It is known that incineration process may result in naturally occurring radioactive materials (NORM) to be concentrated. In this study we have measured three samples consist of by-product from the operation process such as slag, filter cake and fly ash. Other various environmental media such as air, surface water, groundwater and soil within and around the plant have also been analysed for their radioactivity levels. The concentration of Ra-226, Ac-228 and K-40 in slag are 0.062 Bq/g, 0.016 Bq/g and 0.19 Bq/g respectively.more » The total activity (Ra{sub eq}) in slag is 99.5 Bq/kg. The concentration in fly ash is 0.032 Bq/g, 0.16 Bq/g and 0.34 Bq/g for Ra-226, Ac-228 and K-40 respectively resulting in Raeq of 287.0 Bq/kg. For filter cake, the concentration is 0.13 Bq/g, 0.031 Bq/g and 0.33 Bq/g for Ra-226, Ac-228 and K-40 respectively resulting in Raeq of 199.7 Bq/kg. The external radiation level ranges from 0.08 {mu}Sv/h (Administrative building) to 0.35 {mu}Sv/h (TENORM storage area). The concentration level of radon and thoron progeny varies from 0.0001 to 0.0016 WL and 0.0006 WL to 0.002 WL respectively. For soil samples, the activity ranges from 0.11 Bq/g to 0.29 Bq/g, 0.06 Bq/g to 0.18 Bq/g and 0.065 Bq/g to 0.38 Bq/g for Ra-226, Ac-228 and K-40 respectively. While activity in water, except for a trace of K-40, it is non-detectable.« less

THE QUESTIONS OF HEALTH HAZARDS FROM THE INHALATION OF INSOLUBLE URANIUM AND THORIUM OXIDES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hodge, H.C.; Thomas, R.G.

1958-10-31

The insoluble compounds of uranium and thorium, particularly the oxides, are important in the development of atomic energy. Thc questions of health hazards from exposures to dusts of these insoluble compounds are strikily simlar in many but not all respects, Among the similarities may be listed the following facts: The insoluble compounds present no chemical hazard. Both uranium and thorium dioxides, for example, are remarkably inert physiologically. No radiation injuries have so far been described in the lungs of experimental animals inhaling dust concentrations many times the recommended MAC. The lungs of a few dogs studied seven years after excessivemore » inhalation exposures to ThO/sub 2/ gave negative histological findings although high concentrations of thorium were present. The MACs for insoluble uranium and for inxoluble thorium dusts are identical, specifically 3 x 10/sup -11/ c/1. Calculated on a radiation basis, a lower MAC is appropriate for thorium. Based on a considerable body of information from cted. For both uranium and thorium dioxides fecal excretion reflects the immediate exposure to dusty atmospheres. Urine analyses are a prime index of uranium exposure whereas the presence of the much less soluble thorium dioxide in the lung cannot be thus assessed. Breath thoron extimnations or possibly measurements using a whole body counter have been recommended as indices of thorium exposure. The fundamental question depends on the radiosensitivity of the lung and of the pulmonary lymph nodes; neither the production of radiation injury nor the production of cancer are evaluated at present with respect to dosage of radiation. The lung tissues of the dogs described above must have received several thousand rem during the 7 year period. The pulmonary lymph modes must have received considerably more radiation because the concentrations in these nodes e use of the insoluble oxides and the low MACs combine to raise recurring questions of health hazards. (auth)« less

Diffusive Soil Degassing of Radon and Carbon Dioxide at Ilopango Caldera, El Salvador, Central America

NASA Astrophysics Data System (ADS)

Ransom, L.; Lopez, D. L.; Hernandez, P.

2001-12-01

Ilopango Caldera lies 10 Km east of San Salvador, El Salvador and holds Ilopango Lake, the largest body of fresh water in El Salvador. There is currently no observed fumarolic activity within the caldera system. However, the last eruption occurred in 1880. In November - December, 1999, radon gas concentrations (pCi/l) were measured using a Pylon AB5 radon monitor, and flux of CO2 (g/m2/day) was determined using the accumulation chamber method at 106 sampling stations around the lake, along and across the caldera walls. Gas samples were also collected to determine the isotopic composition of C in CO2. CO2 fluxes did not show high values characteristic of other volcanic systems, values ranged from 0.7 to 9.2 g/m2/day with an average value of 3.9. These values are similar to the low values of the background population observed in nearby San Salvador volcano. Highest values are observed to the east and west of the lake. Isotopic values for C in soil gases do not show an important magmatic component. Radon concentrations present three distinct populations with the highest values occurring to the southwest. Thoron concentrations are higher close to the caldera walls than inside the caldera due to the possible higher rock fracturing in that region. Measurements taken in March 2001, after the January 13 and February 13, 2001 earthquakes did not show significant variations in CO2 fluxes. However, radon concentrations varied due to the high seismicity that lasted several months after these earthquakes. These results suggest that the magmatic system of Ilopango Caldera is not emitting high fluxes of CO2 to the atmosphere throughout the caldera soils. Subaquatic emissions of CO2 have not been evaluated. However, subaquatic hydrothermal discharges have not been identified at this calderic lake.

Mortality among male workers at a thorium-processing plant.

PubMed

Polednak, A P; Stehney, A F; Lucas, H F

1983-01-01

The long-term health effects of exposure to thorium are of interest because of the possible increased use of thorium as an energy source in reactors using 232Th to produce 233U. Mortality is described in a cohort of 3039 men who were employed between 1940 and 1973 at a company involved in the production of thorium and rare earth chemicals from monazite sand. Based on deaths ascertained by the Social Security Administration and mortality rates for U.S. white males, the standardized mortality ratio (SMR) for all causes was 1.05 with 95% confidence limits (95% CL) of 0.96 and 1.15. Much of the excess mortality was attributable to non-occupational motor vehicle accidents (SMR = 1.64; 95% CL = 1.16 and 2.23), but SMRs were also high for lung cancer (1.44; 95% CL = 0.98 and 2.02), pancreatic cancer (2.01; 95% CL = 0.92 and 3.82), and diseases of the respiratory system (1.31; 95% CL = 0.92 and 1.83). In a subgroup of 592 men who worked for at least one year in selected jobs (indicative of highest exposure to thorium and thoron) that was followed up more intensively, the SMR for pancreatic cancer was significantly elevated (i.e. 4.13; 95% confidence limits = 1.34 and 9.63). The SMR for lung cancer was 1.68 (95% CL = 0.81 and 3.09), while that for respiratory diseases was 1.20 (95% CL = 0.52 and 2.37). Information on smoking habits in a sample of survivors suggested that smoking could have explained at least part of the excess mortality from lung and pancreatic cancer and from diseases of the respiratory system. Continued follow-up of the cohort through morbidity and mortality studies is needed to evaluate further the possible long-term effects of exposure to radioactivity and chemicals in the thorium extraction process.

Radon Dose Determination for Cave Guides in Czech Republic

NASA Astrophysics Data System (ADS)

Thinova, Lenka; Rovenska, Katerina

2008-08-01

According to recommended approach there are six (from total of twelve) open-to-public caves in Czech Republic, reaching near to an effective lung-dose of 6mSv/year. A conservative approach for estimating the potential effective lung-dose in caves (or underground) is based on two season's measurements, using solid state alpha track detector (Kodak in plastic diffusion chamber). The obtained dataset is converted into an annual effective dose, in agreement with the ICRP65 recommendation, using the "cave factor" 1.5. The value of "cave factor" which depends on the spectrum of aerosol particles, or on the proportional representation of the unattached/attached ratio (6.5 : 93.5 for residential places, 13.6 : 86.4 for caves due to lower concentration of free aerosols) and on the equilibrium factor. Thus conversion factor is 1.5 times higher in comparison with ICRP 65. Is this correct? Because a more precisely determined dose value would have a significant impact on radon remedies, or on restricting the time workers stay underground, a series of measurement was initiated in 2003 with the aim to specify input data, computation and errors in effective dose assessment in each one of the evaluated caves separately. The enhancement of personal dosimetry for underground work places includes a study of the given questions, from the following points of view in each cave: continual radon measurement; regular measurements of radon and its daughters to estimate the equilibrium factor and the presence of free 218Po; regular indoor air flow measurements to study the location of the radon supply and its transfer among individual areas of the cave; natural radioactive element content evaluation in subsoil and in water inside/outside, a study of the radon sources in the cave; determination of the free fraction from continual unattached and attached fraction measurement (grid and filter); thoron measurement. Air flow measurements provide very interesting information about the origin of "radon pockets" with very high radon concentration, and enable study of the location of the radon supply and its transfer among individual areas of the cave. Most of the results show the equilibrium factor around F = 0.2-0.7 and the unattached fraction around 2%-30%. One of the most important question remains: how accurately was the unattached fraction measured? Part of this project was to verify the influence of etched track detector position in the cave.

Soil radon profile of the Alhama de Murcia Fault: implications in tectonic segmentation

NASA Astrophysics Data System (ADS)

Bejar-Pizarro, M.; Perez Lopez, R.; Fernández Cortés, A.; Martínez-Díaz, J. J.; Staller, A.; Sánchez-Malo, A.; Sanz, E.; Cuezva, S.; Sánchez-Moral, S.

2017-12-01

Soil radon exhalation in active faults has been reported in several cases. Mobilization of radon gas in tectonic areas is related to CO2emission, acting as gas carrier from deeper fractured zones. Fluctuation of radon values can be correlated with earthquake occurrence. We have used the soil radon emission for characterizing different tectonic segment of the Alhama de Murcia Fault (FAM), one of the most active on-shore tectonic faults in Spain. The FAM is a NE-SW trending strike-slip fault with reverse component, 90 km long and it is capable to trigger M7 earthquakes, as far as several paleoseismic studies shown. The last destructive earthquake took place in 2011 and killed 9 people. Tectonic segmentation of this fault has been proposed, with a tectonic slip-rate close to 0.1 mm/yr from geomorphic evidence, whereas 0.5 mm/yr has been suggested from GPS geodetic measurements. We have developed a perpendicular profile for measuring the soil radon exhalation, in relationship with three principal segments of FAM from west to east: (1) Goñar-Lorca segment, (2) Lorca Totana segment and (3) Alhama segment. We have introduced radon passive detectors equipped with LR115 films in colluvium detritic deposits and at 0.8 m depth. Using detritic deposits affected by Quaternary fault movement we assure equal permeability conditions for radon transport. We used passive closed housings type DRF, with a filter that avoid thoron disturbance. Results show the largest values of radon emission close to the Quaternary surface ruptures (ca 3-5.5 kBq/m3). Furthermore, the Goñar segment exhibits the highest value (6 kBq/m3) although the Lorca segment shows an isotopic signal of 13dCO2 (-7.24‰) which indicates this is a mantle-rootled CO2, i.e. non-soil derived CO2 flux, likely related to CO2 produced by thermal decarbonation of underlying sedimentary rocks containing more marine carbonate minerals. These results are part of the combined Spanish projects GEIs-SUB (CGL2016- 78318-C2-1-R and CGL2016-78318-C2-2-R) and INTERGEO and SISMOSIMA (CGL2013-47412-C2-1-P, CGL2013-47412-C2-2-P).

Radon Dose Determination for Cave Guides in Czech Republic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thinova, Lenka; Rovenska, Katerina

2008-08-07

According to recommended approach there are six (from total of twelve) open-to-public caves in Czech Republic, reaching near to an effective lung-dose of 6mSv/year. A conservative approach for estimating the potential effective lung-dose in caves (or underground) is based on two season's measurements, using solid state alpha track detector (Kodak in plastic diffusion chamber). The obtained dataset is converted into an annual effective dose, in agreement with the ICRP65 recommendation, using the 'cave factor' 1.5. The value of 'cave factor' which depends on the spectrum of aerosol particles, or on the proportional representation of the unattached/attached ratio (6.5 : 93.5more » for residential places, 13.6 : 86.4 for caves due to lower concentration of free aerosols) and on the equilibrium factor. Thus conversion factor is 1.5 times higher in comparison with ICRP 65. Is this correct? Because a more precisely determined dose value would have a significant impact on radon remedies, or on restricting the time workers stay underground, a series of measurement was initiated in 2003 with the aim to specify input data, computation and errors in effective dose assessment in each one of the evaluated caves separately. The enhancement of personal dosimetry for underground work places includes a study of the given questions, from the following points of view in each cave: continual radon measurement; regular measurements of radon and its daughters to estimate the equilibrium factor and the presence of free {sup 218}Po; regular indoor air flow measurements to study the location of the radon supply and its transfer among individual areas of the cave; natural radioactive element content evaluation in subsoil and in water inside/outside, a study of the radon sources in the cave; determination of the free fraction from continual unattached and attached fraction measurement (grid and filter); thoron measurement. Air flow measurements provide very interesting information about the origin of 'radon pockets' with very high radon concentration, and enable study of the location of the radon supply and its transfer among individual areas of the cave. Most of the results show the equilibrium factor around F = 0.2-0.7 and the unattached fraction around 2%-30%. One of the most important question remains: how accurately was the unattached fraction measured? Part of this project was to verify the influence of etched track detector position in the cave.« less

An instrument for continuous measurement of 220Rn (and 222Rn) using delayed coincidences between 220Rn and 216Po

NASA Astrophysics Data System (ADS)

Bigu, J.; Elliott, J.

1994-05-01

An instrument has been developed for continuous monitoring of 220Rn. The method of data analysis is based on delayed coincidences between 220Rn and 216Po. The instrument basically consists of a scaler equipped with a photomultiplier tube (PMT) to which a scintillation cell (SC) of the flow through type is optically coupled. The scaler is equipped with a pulse output (P/O) port which provides a TTL pulse, +5 V in amplitude and 5 to 10 μs duration for each nuclear event recorded by the SC and its associated electronic circuitry. The P/O port is connected to a 32 bit counter/timer unit operating at 1 MHz which records and stores the time of arrival of pulses. For laboratory use, the counter/timer is connected to the serial port of a laptop PC. However, for field applications, where space and weight pose severe practical limitations, the PC is substituted by an expanded counter/timer unit which incorporates a muprocessor for data analysis, a LCD for data display, and a keypad to key in function instructions. Furthermore, some additional hardware permits the measurement of 220Rn flux density, J( 220Rn) , from soils and other materials. Because total α-particle count, as well as delayed (α - α) coincidence rates are recorded in two separate channels, the method permits the measurement of 222Rn in addition to 220Rn. The method is particularly useful for low concentration levels. The sensitivity of the method primarily depends on the volume of the SC. For a low volume SC (˜0.16 l), a sensitivity of 0.2 h -1/Bq m -3 for 220Rn and 1.4 h -1/Bq m -3 for 222Rn are readily attainable. For a large volume (1.5 l) SC (external PMT used), the sensitivity for 220Rn is ≥ 1.5 h -1/Bq m -3, depending on the SC design and the operating sampling flowrate. (Note: h -1 stands for counts per hour). The above instrument has been used extensively at the National Radon/Thoron Test Facility (NRTTF) of the Elliot Lake Laboratory for routine monitoring of 220Rn levels since 1992. It has also been used for outdoor and indoor 220Rn measurements, as well as for the determination of J( 220Rn) from earthen materials and the like.

Soil gas 222Rn and volcanic activity at El Hierro (Canary Islands) before and after the 2011 submarine eruption

NASA Astrophysics Data System (ADS)

Padilla, G.; Hernández, P. A.; Padrón, E.; Barrancos, J.; Melián, G.; Dionis, S.; Rodríguez, F.; Nolasco, D.; Calvo, D.; Hernández, I.; Pereza, M. D.; Pérez, N. M.

2012-04-01

El Hierro (278 km2) is the southwesternmost island of the Canarian archipelago. From June 19, 2011 to January 2012, more than 11,950 seismic events have been detected by the seismic network of IGN. On 10 October 2011 the earthquake swarm changed its behaviour and produced a harmonic tremor due to magma movement, indicating that a submarine eruption located at 2 km south of La Restinga had started which is still in progress. Since 2003, the ITER Environmental Research Division now integrated in the Instituto Volcanológico de Canarias, INVOLCAN, has regularly performed soil gas surveys at El Hierro as a geochemical tool for volcanic surveillance. Among the investigated gases, soil gas radon (222Rn) and thoron (220Rn) have played a special attention. Both gases are characterized to ascend towards the surface mainly through cracks or faults via diffusion or advection, mechanisms dependent of both soil porosity and permeability, which in turn vary as a function of the stress/strain changes at depth. Years before the starts of the volcanic-seismic crisis on July 17, 2011, a volcanic multidisciplinary surveillance program was implemented at El Hierro including discrete and continuous measurements of 222Rn and 220Rn. Two soil gas 222Rn surveys had been carried out at El Hierro in 2003 and 2011, and four continuous geochemical monitoring stations for 222Rn and 220Rn measurements had been installed (HIE02, HIE03, HIE04 and HIE08). Soil gas 222Rn surveys were carried out at the surface environment of El Hierro after selecting 600 sampling observation sites (about 40 cm depth). Geochemical stations measure 222Rn and 220Rn activities by pumping the gas from a PVC pipe inserted 1m in the ground and thermally isolated. The results of the 2003 and 2011 soil gas 222Rn surveys show clearly a relatively higher observed 222Rn activities in the surface environment on 2011 than those observed on 2003 when no anomalous seismicity were taking place beneath El Hierro. The observed anomalous soil gas 222Rn activities were mainly detected along the major volcano-structural features of the island. The time series recorded at HIE02 and HIE03 showed clear 222Rn precursory signatures of the volcanic eruption. Observed 222Rn activity ranged from negligible values to 16.5 and 1.6 kBqm-3 at HIE02 and HIE03 stations, respectively. Individual 222Rn peaks registered in both stations had been also very useful to forecast later pulses on the volcanic activity. In addition, 222Rn/220Rn ratios in both stations showed a strong increase prior the eruption.

Soil radon and electromagnetic anomalies before the Ileia(Greece) M6.8 earthquake

NASA Astrophysics Data System (ADS)

Nikolopoulos, D.; Vogiannis, E.; Louizi, A.; Zisos, A.

2009-04-01

Radon (222Rn) is a radioactive gas generated by the decay of the naturally occurring 238U series. It is considered very important from radiological point of view, since it accounts for more than half of the natural exposure of the general public. Radon has been used as trace gas in several studies of Earth, hydrogeology and atmosphere, due to its 3.82-day half-life (which allows migration at long distances) and its alpha decay (which enables low level of detection). It has been accounted in the search of earthquake precursors, volcanic processes, fluid circulation in karstic sources and in the study of natural ventilation of underground cavities. Radon anomalies impending great earthquakes have been observed in groundwater, thermal waters soil gas and in underground tunnels. Ileia is a very active tectonic site located in SW Greece, dominated by extensional active seismicity structures (e.g. Alfeios, Neda, Melpeia, Kiparissia-Aetos). Its instrumental and felt seismicity is very high, with more than 600 earthquakes of magnitude greater than 4.0 R in the last 100 years two of which occurred during the last 15 years and were very destructive (5.8 R on 26/3/93 and 6.8 R on 8/6/08 respectively). Hence, it is an area benefiting from the installation of a geophysical monitoring station, where radon exhalation associated with the accumulation or release of tectonic strain can be studied. In the aforementioned consensus, a station for the surveillance of soil radon has been installed in Kardamas Ileias, 3 km south from Amaliada which is the second highly populated city. The station consists of a high precision (calibration certified) active instrument (Alpha Guard-AG, Genitron Ltd.), equipped with an appropriate unit designed for pumping and measurement of radon in soil gas (Soil gas Unit, Genitron Ltd.). Soil radon is driven into AG via a 1-m probe (to minimize meteorological influences) and a 25-m radon proof 25-mm tube (to avoid simultaneous measurement of soil 220Rn-Thoron) with the aid of a mechanical pump working continuously at a rate of 1 L/min. Radon is continuously measured every ten minutes. Additionally, calibrated passive radon dosimeters based on CR-39 Solid State Nuclear Track Detectors (SSNTD's) are periodically (every two weeks) installed in 50 cm holes dug near the 1-m probe and exposed (passively) to soil radon. After the end of each exposure period, the dosimeters are collected and the SSNTD's are measured via standard methods (optical microscopy track counting). Both methods (active with AG and passive with SSNTD's) provide similar estimates of mean soil radon concentration. Active techniques are much more precise and quick, however, they indicated the necessity of periodical checks for the pumping and measurement status, especially after strong rainfalls. The mean soil radon concentration was found fairly constant (to within +/- 10%) and approximately equal to 25-27 kBq m-3. Numerous soil radon concentration anomalies (sudden statistically significant (p

The potential of standards-based agriculture biology as an alternative to traditional biology in California

NASA Astrophysics Data System (ADS)

Sellu, George Sahr

Over the past five decades, several waves of educational reform have influenced K-12 science course offerings and classroom instruction in public education. The effectiveness of educational policies has been increasingly measured by standardized tests. The focus on test scores, content standards, and performance standards (which is a product of recent educational policies) has influenced course offerings and the depth and breadth of curriculum coverage (Linn, 2000). For the better part of the last hundred years, vocational education and traditional education have followed two separate tracks in terms of objectives, policies, and values (Hillison, 1996). Educational reform policies have had varying influences on school programs. For example, elective courses such as Career Technical Education (CTE) courses---which are not considered core academic courses---have been negatively influenced by current educational reform. In the past three decades, there has been gradual movement toward merging vocational and traditional education. It has been difficult for policies from both sides to merge because of differences in objectives for both tracks. Traditional courses have been guided by federal policies, such as No Child Left Behind (NCLB) and Common Core State Standards (CCSS) while the Carl D. Perkins Act (Perkins Act) has shaped CTE courses. It appears that several of the requirements of the Perkins Act meet expectations of traditional education policies. However, there is no direct metric for measuring the contribution of CTE courses toward increased achievement in science as measured by standardized tests. As such, CTE courses will continue to lose resources in order to support courses that prepare students for standardized tests. In order to address some of these challenges over the last three decades, agriculture educators have developed integrated science courses as a means for increasing science achievement scores for agriculture education students in K-12 public schools. Thoron & Meyer (2011) suggested that research into the contribution of integrated science courses toward higher test scores yielded mixed results. This finding may have been due in part to the fact that integrated science courses only incorporate select topics into agriculture education courses. In California, however, agriculture educators have developed standards-based courses such as Agriculture Biology (AgBio) that cover the same content standards as core traditional courses such as traditional biology. Students in both AgBio and traditional biology take the same standardized biology test. This is the first time there has been an opportunity for a fair comparison and a uniform metric for an agriscience course such as AgBio to be directly compared to traditional biology. This study will examine whether there are differences between AgBio and traditional biology with regard to standardized test scores in biology. Furthermore, the study examines differences in perception between teachers and students regarding teaching and learning activities associated with higher achievement in science. The findings of the study could provide a basis for presenting AgBio as a potential alternative to traditional biology. The findings of this study suggest that there are no differences between AgBio and traditional biology students with regard to standardized biology test scores. Additionally, the findings indicate that co-curricular activities in AgBio could contribute higher student achievement in biology. However, further research is required to identify specific activities in AgBio that contribute to higher achievement in science.

Measurements of 222Rn, 220Rn, and CO 2 Emissions in Natural CO 2 Fields in Wyoming: MVA Techniques for Determining Gas Transport and Caprock Integrity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaszuba, John; Sims, Kenneth

An integrated field-laboratory program evaluated the use of radon and CO 2 flux measurements to constrain source and timescale of CO 2 fluxes in environments proximate to CO 2 storage reservoirs. By understanding the type and depth of the gas source, the integrity of a CO 2 storage reservoir can be assessed and monitored. The concept is based on correlations of radon and CO 2 fluxes observed in volcanic systems. This fundamental research is designed to advance the science of Monitoring, Verification, and Accounting (MVA) and to address the Carbon Storage Program goal of developing and validating technologies to ensuremore » 99 percent storage performance. Graduate and undergraduate students conducted the research under the guidance of the Principal Investigators; in doing so they were provided with training opportunities in skills required for implementing and deploying CCS technologies. Although a final method or “tool” was not developed, significant progress was made. The field program identified issues with measuring radon in environments rich in CO 2. Laboratory experiments determined a correction factor to apply to radon measurements made in CO 2-bearing environments. The field program also identified issues with radon and CO 2-flux measurements in soil gases at a natural CO 2 analog. A systematic survey of radon and CO 2 flux in soil gases at the LaBarge CO 2 Field in Southwest Wyoming indicates that measurements of 222Rn (radon), 220Rn (thoron), and CO 2 flux may not be a robust method for monitoring the integrity of a CO 2 storage reservoir. The field program was also not able to correlate radon and CO 2 flux in the CO 2-charged springs of the Thermopolis hydrothermal system. However, this part of the program helped to motivate the aforementioned laboratory experiments that determined correction factors for measuring radon in CO 2-rich environments. A graduate student earned a Master of Science degree for this part of the field program; she is currently employed with a geologic consulting company. Measurement of radon in springs has improved significantly since the field program first began; however, in situ measurement of 222Rn and particularly 220Rn in springs is problematic. Future refinements include simultaneous salinity measurements and systematic corrections, or adjustments to the partition coefficient as needed for more accurate radon concentration determination. A graduate student earned a Master of Science degree for this part of the field program; he is currently employed with a geologic consulting company. Both graduate students are poised to begin work in a CCS technology area. Laboratory experiments evaluated important process-level fundamentals that effect measurements of radon and CO 2. Laboratory tests established that fine-grained source minerals yield higher radon emissivity compared to coarser-sized source minerals; subtleties in the dataset suggest that grain size alone is not fully representative of all the processes controlling the ability of radon to escape its mineral host. Emissivity for both 222Rn and 220Rn increases linearly with temperature due to reaction of rocks with water, consistent with faster diffusion and enhanced mineral dissolution at higher temperatures. The presence of CO 2 changes the relative importance of the factors that control release of radon. Emissivity for both 222Rn and 220Rn in CO 2-bearing experiments is greater at all temperatures compared to the experiments without CO 2, but emissivity does not increase as a simple function of temperature. Governing processes may include a balance between enhanced dissolution versus carbonate mineral formation in CO 2-rich waters.« less

PRESSURIZED WATER REACTOR (PWR) PROJECT TECHNICAL PROGRESS REPORT FOR THE PERIOD DECEMBER 24, 1959 TO FEBRUARY 23, 1960

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

< 9 A < 2 6 < 7 4 8 9 6 2 6 equalizing vent valves on air locks 2, 4, and 5 was completed. An evaluation of the failed main coolant pump No. 1-80-F-737 was completed. The design for installing combination ball check and manual stop valves on the boiler water level sight glasses, to prevent the escape of steam should a defective sight glass develop, was completed. The main coolant pumps No. 80 and No. 79 were modified by increasing the radial clearance of the impeller wear ring and by removing the upper labyrinth ring. A designmore » for relocating the cooling water flow orifice 17-J4-17 was completed. Metallurgy: Preliminary data from the Bett 69-1 in-pile thermal conductivity capsules indicate that the thermal conductivity of as-sintered ZrO/sub 2/ 34 wt.% UO/sub 2/ appears to decrease from an initial value of about 1.6 Btu/hr-ft- deg F to about 0.7 Btu/hr-ft- deg F after 17 days irradiation in an estimated perturbed flux of 4 x 10/sup 13/. The thermal conductivities of UO/sub 2/ and BeO 51 wt.% UO/sub 2/ fuel remained unchanged during this time. Examination of the two failed X-3-1 fuel plates and the two failed CR-V-m fuel plates showed that a definite burnup limitation exists for bulk UO/sub 2/i of about 16 x 10/sup 20/ to 21.5 x 10/sup 20/ fissions/cc at which point the fuel increases in volume about 4- -5%. Irradiation of both fine and coarse dis-persions of 28 wt.% UO/sub 2/in BeO to exposures of about 11 x 10/sup 20/ fissions/cc shows this material has very poor dimensional stabllity and poor fission gas retention ability. The fine particles dispersion showed approximately 4.8 times the thickness increase as did the coarse particles. Interim examination of a bulk B/sub 4/ burnable poison plate irradiated in the HB-1 loop to about 60 at.% B/sup 10/ burnup showed a 17% increase in plate thickness. The technical feasibility of fabricating blanket receptacles with full length fuel channels and an integral cover plate by form rolling was established. Hack-pressure-bonding appears to be a suitable means of incorporating void volume in fuel compartments of oxide plates. High density (99% T.D.) and improved microstructure of B/sub 4/C-SiC burnable poisons are achieved when small (2 micron) B/sub 4/C particle size powder is used ia hot pressing compacts. Measurements of the self-diffusion coefficients of uranium in UO/sub 2/ by the method of surface activity decrease were completed. Experiments on the diffusion of Xe/sup 133/ in Core 2--type UO/sup 2/ fuel platelets were completed. Diffusion anaeals carried out at 1000 deg C on samples from the X-3-1 and the 14-28 irradiation tests show that the apparent diffusion coefficient for Kr/sup 85/ incresses considerably with burnup. An average activation energy for thoron emanation in UO/sub 2/ was estimated to be 44 kcal/mole. An initial experiment on the release of helium from slightly irradiated B/sub 4/C at 900 deg C resulted in a diffusion coefficient for helium of 3.5 x 10/sup -8/ Physics: Calculatad values for seed-blanket power sharing as a function of PWR-1 Seed 1 life were compared with measured data obtained from thermal instrumentation at Shippingport. Two-dimensional depletion studies in the PWR-2 "composite cell" geometry were completed for seed assembly configurations having different radial fuel zoning. An eighth core representation is being employed for a two- dimensional depletion calculation of PWR-2. An analysis of the effect on the axial power distribution of the nonuniform temperature distribution in an 8 ft PWR-2 core loaded with 295 kg of U/sup 235/ indicated that local variations in power density of as much as 15% may occur, relative to the distribution that would exist if the axial temperature distribution were uniform. A technique was developed which makes possible an approximately correct description of the neutron capture rate within small rectangular boron wafers in diffusion theory calculations. Seed peaking factors measured in a five-cluster slab of PWR-2 mock- up materials were measured and compared with calculated peaking factors obtained using the nuclear« less

Radon concentration of waters in Greece and Cyprus

NASA Astrophysics Data System (ADS)

Nikolopoulos, D.; Vogiannis, E.; Louizi, A.

2009-04-01

Radon (222Rn) is a radioactive gas generated by the decay of the naturally occurring 238U series. It is considered very important from radiological point of view, since it is the most significant natural source of human radiation exposure (approximately 50% from all natural sources). Radon is present in soil, rocks, building materials and waters. Through diffusion and convection, radon migrates and emanates to the atmosphere. Outdoors, radon concentrates at low levels (in the order of 10 Bq/m3). However indoors, radon accumulates significantly. It is trivial to observe indoor environments with high radon levels (in the order of 400 Bq/m3 or higher). Radon accumulation indoors, depends on the composition of the underlying soil and rock formation, on building materials, meteorological parameters, ventilation, heating and water use. Although soil and building materials are the most significant radon sources, there have been reported elevated radon concentrations in building structures due to entering water. It is the radon concentrations in the entering water, the volume and the way of water usage, separated or in combination, that result in large amounts of radon in indoor air. Moreover, radon is a factor of stomach radiation burden due to water consumption. This burden is estimated by measurements of radon concentrations in waters. Due to the health impact of radon exposure, the reporting team continuously measures radon. This work focused on the radon concentrations exposure due to water consumption and use in Greece and Cyprus. Various locations in Greece and Cyprus were accessed taking into consideration existing natural radioactivity data (mainly radon in water), however under the restriction of the capability of movement. Radon in water was measured by Alpha Guard (Genitron Ltd) via a special unit (Aqua Kit). This unit consists of a vessel used for forced degassing of radon diluted in water samples, a security vessel used for water drop deposition. Vessels and Alpha Guard are connected via plastic radon proof tubes. Forced degassing of radon gas is performed by circulating the air in the set up with the use of a pump. Water sampling (to avoid radon escape) was driven by a strict protocol. Water taps were opened for 10 minutes before drawing the sample. Glass storage vessels of 200 to 1000 ml, with adjustment glass stoppers with standard NS 29/32 grounding, as well as sealing rings and granted security clamps for taper grounding, were completely filled slowly and immediately closed (to avoid the formation of air bubbles). Similar procedure (except tap opening) was followed for underground and surface waters. Laboratory measurements were performed at least one hour after drawing the sample in order to assure the full decay of any thoron content and to the minimum achievable time interval, so as the radon content to be the highest possible to allow higher precision. For the measurement the glass stopper was removed and immediately exchanged with the degassing cap. Afterwards water quantity was reduced to about half and measured. From the measurements, the mean annual equivalent dose rate (aEDr) delivered to stomach due to ingestion and the contribution to aEDr due to inhalation of radon in drinking water were calculated as using the EURATOM 2001 dose conversion factor (0.00144 mSv/Bq). Radon concentrations in drinking waters ranged between (1.1+/-0.5) Bq/L and (15+/4) Bq/L. Only three samples collected from the radon prone area of Arnea Chalkidikis presented high radon concentrations (120+/20 Bq/L, 320+/-40 Bq/L, 410+/-50 Bq/L). Radon concentrations in underground waters ranged between (1.2+/-0.7) Bq/L and (14.7+/-1.1) Bq/L. The corresponding concentration range in surface waters was (2.7+/-0.8) Bq/L and (24+/-6) Bq/L. The radon concentrations in thermal waters (some of which are used for drinking) were quite higher (in the range of (220+/-20) to (340+/-40) Bq/L). In both countries, no correlation of radon in underground waters with depth was observed. In Cyprus, the highest water radon concentrations were found in Protaras region. The average value of radon in water resulted to an average contribution of 0.3% in respect to the average indoor radon concentration and mean annual effective dose. The corresponding values for Greece resulted to a 0.1% contribution. This contribution is considered quite low both for Cyprus and Greece (0.1%) and hence this part of effective dose may be considered of slighter significance compared to inhalation of total radon. Yet this contribution is comparable to the effective dose values delivered through medical uses of radiation. On the other hand, significant doses are delivered to stomach of the Cypriot and Greek population due to ingested radon following water consumption. The corresponding average annual dose rates were found equal to 0.085 mSv/y (S.D of 0.080 mSv/y) for Cyprus and 0.081 mSv/y (S.D of 0.081 mSv/y) for Greece.