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1.
To obtain an average dose from 222Rn to the people in Aomori Prefecture where the first Japan"s nuclear fuel cycling facilities are now under construction, we surveyed 222Rn concentrations in 109 dwellings in the Prefecture from 1992 to 1996. The outdoor 222Rn concentrations were also measured in gardens of 15 dwellings. The 222Rn concentrations were measured with passive 222Rn detectors which used a polycarbonate film for counting a-ray and could separate concentrations of 222Rn from 220Rn. Counting efficiencies of the detectors were calibrated with a standard 222Rn chamber in the Environmental Measurement Laboratory in USA and in the National Radiological Protection Board in UK. Geometric means of 222Rn concentration were 13 and 4.4 Bq .m -3 in the dwellings and outdoor, respectively. These values were consistent to nationwide survey results in Japan. The 222Rn concentrations in the dwellings depended on their age. The concentrations were higher in recent dwellings than in older ones. The radiation dose from 222Rn was estimated, taking into account the occupancy factor for inside and outside of dwellings. The annual dose was 0.32 mSv .y -1, and 99% of the dose came from the exposure to 222Rn inside the dwelling. 相似文献
2.
The activity concentration and absorbed gamma dose rates due to primordial radionuclides ( 238U, 232Th and 40K) have been determined for the soil of Coimbatore city using NaI(Tl) gamma-ray spectrometer. The average activity concentrations
of 232Th, 238U and 40K in the soil samples have been found to be 31.4 Bq·kg −1, 12.8 Bq·kg −1 and 698.0 Bq·kg −1, respectively, which give the total gamma dose rate contribution of 56.4 nGy·h −1. Grab sampling technique has been used to determine the indoor radon ( 222Rn) and thoron ( 220Rn) progeny levels in different dwellings in the city. The concentrations of radon and thoron progenies range from 0.4 to
10.4 and from 0.7 to 12.7 mWL with a mean value of 1.4 mWL and 3.1 mWL, respectively. The annual effective dose due to radon
and thoron progeny has been found to be 0.14 mSv·y −1. 相似文献
3.
The present study in the Metropolitan Zone of Guadalajara (MZG) in the state of Jalisco was carried out along 2007. 222Rn (radon) and 220Rn (thoron) levels were measured in single-family dwellings in normal living conditions (open house condition). Measurements
were accomplished by Electret Passive Environmental Radon Monitors (E-PERM) in different configurations. At the same time
and for the same period, the gamma dose rate was measured by a LiF: Mg, Cu, P+PTFE thermoluminiscent dosimeter. A Quality
Assurance Program was improved. Results show a lognormal distribution of annual concentrations and seasonal variations. Mean
annual concentrations of radon were lower than US EPA and EEC action values. 220Rn levels appear to be higher than the typical value determined by the UNSCEAR Reports (1993 and 2000). Performance of different
E-PERM configurations accomplishes the US EPA guidelines and yield useful results for diverse situations. Gamma rate dose
was higher than that of the Metropolitan Zone of Mexico. 相似文献
4.
Domestic radioactivity has been studied by using LR-115 and CR-39 solid state nuclear track detectors (SNTD) and a suitable beta- and gamma-gaseous counter. A new calibration method, based on measuring thoron ( 220Rn) to radon ( 222Rn) ratios, has been developed for determining the -activity originating from radon in different Marrakechi dwellings. The influence of building materials as well as pollution and airing factors, on domestic radioactivity has been investigated. 相似文献
5.
This paper presents the extent of thoron ( 220Rn) interference in the radon ( 222Rn) exhalation rate, measured by solid state nuclear track detector based ‘Can’ technique. Experiments were carried out following the standard procedure of ‘Can’ technique as well as active technique as a reference method for 222Rn and 220Rn exhalation measurements. It was found that 220Rn interference may lead to overestimation of 222Rn exhalation by a significant factor which can be as high as 12 depending upon the rate of 220Rn exhalation from samples. 相似文献
6.
The activity concentrations of 226Ra, 228Ra and 222Rn were measured in 87 groundwater samples to estimate the activity concentrations of these radionuclides and health impact due to intake of these radionuclides in groundwater of Jordan. The mean activity concentrations of 226Ra, 228Ra and 222Rn in groundwater were found to be 0.293?±?0.005 Bq L?1, 0.508?±?0.009 Bq L?1 and 58.829?±?8.824 Bq L?1, respectively. They give a mean annual effective dose of 0.481 mSv with mean lifetime risk of 24.599?×?10?4, exceeding the admissible limit of 10?4. Most of the received annual effective dose (59.15% of the total) is attributed to 228Ra. 相似文献
7.
A new Monte Carlo computer code was developed for determining the detection efficiencies of the CR-39 and LR-115 II solid state nuclear track detectors (SSNTD) for a-particles emitted by radon ( 222Rn) and thoron ( 220Rn) series inside the atmosphere of dwelling rooms. Alpha-activities due to radon, thoron and their decay products, were evaluated for the determination of the detection efficiencies of the SSNTD utilized for the emitted a-particles by measuring the corresponding track densities. The influence of the ventilation rate and building material on the concentration of radon, thoron and their progenies was investigated. Equilibrium factors between radon and its progeny and between thoron and its daughters have been evaluated in the air of the rooms. 相似文献
8.
A new determination method for 222Rn and 220Rn in water sample was developed by extracting radon with toluene and applying the integral counting method with a liquid
scintillation counter. The essential characteristics of the methods are, (1) extraction of radon with toluene from water,
(2) finding absolute counts and making corrections for the quenching effect by the adoption of the integral counting method,
(3) the determination of 222Rn and 220Rn was performed by counting the activity of 220Rn with its descendants and of ThB ( 212Pb) with its descendants in a radioactive equilibrium, respectively, (4) realizing high sensitivity by simultaneous counting
of α, β − particles emitted from the decay products formed in toluene. The lowest detection limit obtained by the present method was
5.0·10 −13 Ci/l for 222Rn and 6.8·10 −8 Ci/l for 220Rn in water. 相似文献
9.
A walk-in type 222Rn calibration chamber (~ 22 m3) is established at the Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, India which is being used by research groups working on 222Rn in India and other countries as well. In recent times, computational fluid dynamics (CFD) technique is opted as an alternative approach for the prediction of 222Rn concentration profile in the closed domain. CFD simulations were carried out to study the transient build-up and spatial behavior of 222Rn concentration in the calibration chamber. Measurements were performed using active 222Rn measuring devices and results of the CFD predictions and direct measurements were compared. A good agreement was observed between the simulated and experimental results with deviation between the two entities being ~ 3% in the case of transient build up and ~ 8% in the case of spatial distribution of 222Rn concentration. 相似文献
10.
We have investigated the possibility of determining the relative concentrations of two radon isotopes ( 222Rn and 220Rn) in the air, using solid state nuclear track detectors (CR-39) as alpha spectrometers. The detectors were exposed to 222Rn and its daughters and 220Rn and its daughters in the air. Analyzing only roundish tracks, it was observed that the performance of CR-39 as alpha spectrometer varies with etching time, improving markedly for long etching times. 相似文献
11.
The present study presents an overview of the distribution of radon ( 222Rn) activity concentration in the groundwater samples and their annual effective dose exposure in the Varahi and Markandeya
command areas. Radon measurement was made using Durridge RAD-7 radon-in-air monitor, using RAD H 2O technique with closed loop aeration concept. The measured 222Rn activities in 16 groundwater samples of Varahi command area ranged between 0.2 ± 0.4 and 10.1 ± 1.7 Bq L −1 with an average value of 2.07 ± 0.84 Bq L −1, well within the EPA’s maximum contaminant level (MCL) of 11.1 Bq L −1. In contrast, the recorded 222Rn activities in 14 groundwater samples of Markandeya command area found to vary from 2.21 ± 1.66 to 27.3 ± 0.787 Bq L −1 with an average value of 9.30 ± 1.45 Bq L −1. 21.4% of the samples (sample no. RMR5, RMR11 and RMR12) in the Markandeya command area exceeded the EPA’s MCL of 11.1 Bq L −1 and it was found that some samples in both the command areas were found to have radon values close to MCL value. The spatial
variation in the radon concentration in the Varahi and Markandeya command area were delineated by constructing the contour
map. The total annual effective dose resulting from radon in groundwater of both Varahi and Markandeya command areas were
significantly lower than the UNSCEAR and WHO recommended limit for members of the public of 1 mSv year −1. 相似文献
12.
In this work, the radionuclide activity concentrations of 226Ra, 232Th and 40K in surface soils and radon levels in dwellings of Karabük, Turkey were determined in order to evaluate the environmental
radioactivity. Concentrations of 226Ra, 232Th and 40K radionuclides were determined using gamma spectrometry with using HPGe detector. The etch track detectors (CR-39) were used
to determine the distribution of radon concentrations. The average activity concentrations for 226Ra, 232Th and 40K were found as 21.0, 23.5 and 363.5 Bq kg −1, respectively. The calculated average annual effective dose equivalent from the outdoor terrestrial gamma radiation from
226Ra, 232Th and 40K is 53.5 μSv y −1. The average radon concentration and annual effective dose equivalent of 222Rn in Karabük dwellings were obtained 131.6 Bqm −3 and 3.32 mSv y −1, respectively. The evaluated data were compared with the data obtained from different countries. 相似文献
13.
ABSTRACTRadon ( 222Rn) and its parent radionuclide Radium ( 226Ra) are classified as carcinogen. Human exposes to radon in water via inhalation and ingestion, although ingestion is the only way for radium to enter the human body. In this research, tap water collected from Bornova distinct was studied to determine the concentration of radon ( 222Rn) and radium ( 226Ra) for evaluating their radiological impact. For this reason, the annual effective doses for ingestion and inhalation were estimated. The measurements were performed using a collector chamber method. The mean concentrations of 222Rn and 226Ra were determined as 0.85 and 0.76 Bq/L, respectively. It can be stated that the 222Rn and 226Ra concentrations of tap waters here are lower than the international reference levels. Obtained concentration levels were applied to estimate annual effective dose due to the inhalation and ingestion. The dose values are also found to be lower than the recommended maximum values. On the other hand, it should be considered that consumption of these waters (2 L) and average radon and radium concentrations of water are the significant factors for estimating doses. 相似文献
14.
As part of a national program to determine public exposure to natural radiation, indoor air 222Rn concentrations were determined in dwellings of Turkey. The 222Rn concentrations were measured with time-integrating passive nuclear etched track detectors in 27 provincial centers. The
indoor radon concentrations were found to be in the range of 10-380 Bq .m -3.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
Summary A portable liquid scintillation counter was applied for the analysis of alpha-ray energy spectrum to determine the ratio of
220Rn/ 222Rn in fumarolic gas in the field. A surface-polished vial was developed, by which a Gaussian distribution could be approximated
for the alpha-ray energy spectra and the peak areas of the nuclides could be estimated independently, because of the wide
FWHM in the liquid scientillation pulse. A fumarolic gas sample was collected in Mt. Kamiyama (Hakoneyama geothermal field
in Japan) having low 220Rn/ 222Rn ratio of 2.20±0.13. 相似文献
16.
The radionuclides 222Rn and 220Rn are measured by incorporating their daughters 214Pb and 212Pb in a very thin layer of PbS and accumulating the alpha spectrum of their daughter products 214Po and 212Po. The median yield was measured as 88% using a known amount of 210Pb tracer. A single fumarole and all 23 geothermal wells tested were found to contain 220Rn. As isotopes of Th, Bi, Po and Ra, are also absorbed in the PbS layer, the method can be used for determinations of these in tap-water. 相似文献
17.
The determination of soil-gas anomalies especially 222Rn anomalies, are important to precisely locate fault traces, as well as to investigate earthquake precursors. In this paper, we have studied and compared new rapid methods for on site determinations of radon ( 222Rn), thoron ( 220Rn) and total radon ( 222Rn+ 220Rn) in soil-gas. These new techniques pump the soil-gas continuously from the soil through a simple sampling tube to the counting cell for one-minute with discarding the excess. Then, either four one-minute counting periods (5-minute technique) or nine one-minute counting intervals (10-minute technique) are followed immediately. In all the methods, conversely to Morse"s method, the first counting period (C1) was not employed for calculations. Three calculation methods for the five-minute technique, two for the ten-minute technique and a modified Morse"s method are compared with theoretical values and different real soil-gases with different radon/thoron ratios. The affect of different flow rates of soil-gases into the counting cell was also investigated. Finally, the ten-minute technique seems to be a little more accurate, but the 5-minute technique is much more suitable for seismic field studies when a much larger number of determinations are required in a short time. 相似文献
18.
In the first part of this paper, the influence of radon ( 222Rn) exhalation rate from walls and air exchange upon its concentration in room air was considered using a simple mathematical room model. The exhalation rates have been determined in ten low ventilated rooms of ten villas in Jeddah city (Western Province) of Saudi Arabia. An electroprecipitation method has been applied for the determination of the 222Rn gas concentration in these rooms. The mean 222Rn gas concentration was found to be 46.80±8.80 Bq m ?3. The mean 222Rn exhalation rate was estimated to be 20.11±6.90 Bq m ?2 h ?1. The mean inhalation dose due to the exposure to 222Rn gas was calculated to be 1.18±2.30 mSv y ?1.The second part of this paper deals with a study of natural radionuclide contents of samples collected from the building materials of these rooms under investigations in part one. Analyses were performed in Marinelli beakers with a gamma spectroscopy system to quantify radioactivity concentrations. The collected samples revealed the presence of the uranium–radium ( 226Ra) and thorium ( 232Th) radioisotopes as well as 40K. The mean activity concentration of 226Ra, 232Th and 40K was determined to be 48.30±5.08, 43.90±5.63 and 223.90±7.55 Bq kg ?1, respectively. These activities amount to a radium equivalent (Ra eq) of 125.96±15.90 Bq kg ?1 and to a mean value of external hazard index ( Hex) of 0.34±0.04. 相似文献
19.
Summary It is well known that the interest in radon concentration indoor as a pollutant emerged during the energy crisis of seventies
which led to reduce ventilation in dwellings. Recently the Euratom Recommendation 2001/928 suggested the necessity of performing
frequent 222Rn checks on tap waters. As a consequence of this Recommendation, Urbino and Perugia Universities carried out a preliminary
222Rn determination on tap waters of the Pesaro-Urbino province. Samplings were carried out in twenty-eight sites and radon concentration
was determined by liquid scintillation counting and gamma-spectrometry. The results obtained by the two techniques were comparable
(the deviation from the mean is lower than 10% for 54.5% of the samples). The resulted 222Rn concentration was very low (5 Bq . l -1 for 43% of the samples) and, therefore, radon in waters cannot be considered as a direct radiological risk for the local
population. 相似文献
20.
Fault traces have been previously located from measurements of 222Rn in soils taken a constant soil-depth across the fault trace. In this paper, we have studied the uranium-series disequilibria of the 226Ra, 222Rn (gas) and 214Bi radionuclides, not only for their horizontal spatial patterns across the fault trace, but also for their vertical spatial patterns near and at the fault trace itself. Radon-222 activities in the soil-gas were measured on-site with a radiation monitor and a Lucas cell. Radium-226 and 214Bi were determined in soil samples in the laboratory by gamma-ray spectroscopy. A new technique employing the measurement of 222Rn versus soil-depth shows a decrease in 222Rn activity at the fault trace due to the much higher soil-gas permeability as a result of the fractured soil, as well as relative larger uranium-series disequilibria, in respect to an increase in 222Rn activity at normal sites, where the soil is not fractured. Finally, it is suggested that fault trace detection could possibly also be performed by measuring 214Bi in surface soils (0-100 cm) along a transect. 相似文献
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