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1.
Radon alpha-activities per unit volume have been measured inside and outside different building material samples by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD). Radon emanation coefficients of the studied building materials have been evaluated. The porosities of the building material samples studied have been determined by using a Monte Carlo calculational method adapted to the experimental conditions and compared with data obtained by the Archimedes's method. The influence of the building material porosity on the radon emanation coefficient has been investigated. 相似文献
2.
Samples have been collected from different layers in a sedimentary phosphatic deposit and sieved. Different granulometric
fractions have been selected. The uranium and thorium contents have been determined in each phosphate sample and its corresponding
selected fractions. Radon ( 222Rn) α-activities per unit volume have been evaluated inside and outside each phosphate sample and its corresponding selected
fractions by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD). The radon emanation coefficient in
each phosphate layer has been determined and the global radon alpha activity outside a parallelepipedic block of the layers
studied was evaluated. The influence of the lithology and granulation on the radon emanation has been studied. 相似文献
3.
A simple method for the determination of the radon emanation fraction was studied using a liquid scintillation counter. The
radon activity of the gaseous phase in a closed container was measured 1 day and 35 days after sealing and used to calculate
the radon emanation fraction. Radon leakage from the container was investigated using a 226Ra radioactive standard solution (SRM4967, NIST) to plot a radon growth curve. The method was applied to materials that typically
contain a high level of radium, such as phosphogypsum, phosphate fertilizer and a rock sample. The effect of temperature on
the radon emanation fraction from the materials was investigated at 0, 10, 20, 30 and 40 °C. It was found that there is a
linear correlation ( R
2 = 0.746 − 0.946) between temperature and the emanation fraction. Within the temperature range, the radon emanation fractions
were 0.241–0.466 for phosphogypsum, 0.225–0.351 for phosphate fertilizer and 0.154–0.351 for the rock sample. 相似文献
4.
The applicability of a radon emanation system to radium determination in fine-grained solid samples has been investigated by means of a closed radon emanation system consisting of a radon monitor and an aluminium vessel. The system has been calibrated with radium-containing fine-grained samples (e.g. phosphogypsum, granite and pitchblende) and the evaluation of the calibration data included linearity, detection limits and analytical resolution of the method. The studied radon emanation system presents very good linear response ( R 2 = 0.99) to the radium content of the samples, the detection limit for radon is 25 Bq m ?3 and the analytical resolution 15 Bq m ?3. In addition, the relation between particle size of the materials and radon emanation has indicated that the applicability of the radon emanation system to radium determination is strongly depended not only on the mineral type but also on the particle size of the grained material. 相似文献
5.
Radon emanation from surface water and groundwater samples has been studied by using CR-39 and LR-115 solid state nuclear track detectors (SSNTD). A calibration method for determining the thoron and radon concentrations of the water samples studied has been developed. The effect of pollution due to coal fly ashes, cement and granite dusts on the radon emanation from water samples has been investigated. The influence of the radon source on the radon emanation rates from water samples has been studied. 相似文献
6.
Indoor radon and thoron concentrations were dominated with their exhalation rate from building materials. Thus, the evaluation
of exhalation rate with highly precise is important. This paper presented a new technique to measure the dependence radon/thoron
exhalation rate, from building materials used in Japan, on absolute humidity. The measurement technique consisted of a solid
state alpha detector equipped a ventilation-type chamber and humidity control system in a flow through method. The exhalation
rate of dried samples (Indian red granite and Japanese gray granite) was measured at various absolute humidity levels in the
range of 1–20 g cm −3. It was found that exhalation rate increased exponential with increasing of absolute humidity for both samples. Furthermore,
the dependence of radon emanation coefficient on building material’s temperature was also studied using an accumulation chamber
equipped with scintillation cell alpha detector. The emanation coefficient of dry sample increased proportionally with increasing
the material’s temperature with a correlation factor of 0.88. 相似文献
7.
Radon-to-thoron ratios as well as radon and thoron activity concentrations in different underground water samples belonging to different aquifers in the Moroccan Middle Atlas area have been evaluated by LR-115 and CR-39 solid state nuclear track detectors (SSNTD) using a new calibration method. The radon isotope ( 222Rn) was used as a tracer for studying the water exchange between different aquifers of the area studied. The influence of the lithological and hydrogeological parameters of the aquifers on radon emanation were investigated. 相似文献
8.
Measurements have been made of radon ( 222Rn), release from diverse quaternary samples collected from different sediment deposits in the Errachidia and Beni-Mellal areas (Morocco). The radon diffusion coefficient as one of some important parameters of radon transport in the soil has been measured using solid state nuclear track detectors (SSNTD). Radon -activity, uranium content and radon exhalation rate have been determined in the studied samples. Uranium concentrations were found to vary from 0.14 to 9.52 ppm whereas the radon exhalation rate varied from 0.003 to 0.145 Bq .m -2.h -1. A positive correlation has been found between radon exhalation rate and uranium content in the studied samples. The average radon diffusion coefficients were found to vary from (1.26±0.09) .10 -6 m 2.s -1 to (4.3±0.36) .10 -6 m 2.s -1. Furthermore, the correlation between 222Rn diffusion coefficient and porosity are also discussed. 相似文献
9.
Experiments were designed to evaluate, in a controlled way, some of the variations that can be expected in radon concentration in soil due mainly to meteorological factors and to close spacing monitoring in the field. Electronic continuous radon monitoring and the track-etch method were used to record the radon -decay. The radon emanation in daily measurements and in long term surveys showed a general effect modulated by temperature and pressure variations. Radon monitoring in soil for nearby stations showed that a 10% range of variation can be expected with the track-etch method and as a result of non-homogeneous emanation pattern of the soil. 相似文献
10.
Indoor radon and its annual effective dose from the building materials commonly used in Thailand were reported. Radon emission from samples collected in the closed chamber was measured by an ionization chamber. Indoor radon and the annual effective dose were calculated from radon concentration in the closed chamber. Granite yields the highest annual effective dose. Three samples of granite shown the annual effective dose higher than the annual exposure limit for the general public of 1 mSv year ?1 recommended by the International Commission on Radiological Protection. Applying appropriate surface coating, the radon emission from some building materials has decreased substantially. 相似文献
11.
For the public, indoor radon is the main source of exposure from ionizing radiation. Radon gas originates from the radioactive decay chain of uranium deposited in rocks or in building materials. In the reviews mostly a rather steady radon exhalation has been assumed. In a village of North-East Hungary, however, high radon concentrations have been measured, differing strongly in neighbouring houses and varying in time, due to the interplay of several geochemical phenomena. 相似文献
12.
Summary In order to calibrate vials containing charcoal for measurement of radon, emanation sources of radon were produced in-house using 226Ra salts. Calibrated emanation standards containing solution of 226Ra(NO 3) 2 absorbed into inorganic compounds were prepared. The emanation coefficient of 222Rn for these standards vary from 0.23-0.25. The emanation sources were found to be suitable for calibrating radon monitors. 相似文献
13.
Wasted petroleum, scale and sludge, samples associated with petroleum industries have elevated level of radionuclides concentrations which increase the radiation dose received to the workers. Radon concentration, emanation coefficient and exhalation rate give good information about the radioactivity levels. Twelve samples of scale, sludge and sand, collected from different oil fields in the Red Sea Refineries company for petroleum services in the eastern desert of Egypt, were selected for this study. Radon concentration released from selected samples was measured using AlphaGUARD radon monitor. Radon emanation coefficient and its exhalation rate were calculated based on the measured value of radon concentration. Correlation among radon exhalation rate with radium content and “emanated radon concentration” (radium concentration × emanation coefficient) as well were found to be of 0.94 and 0.99, respectively. Therefore, radon exhalation rate could be useful index for both radium concentration and emanated radon. Radon emanation coefficient was increased more than twice due to water content within material of less than of 10 %. 相似文献
14.
This study was intended to determine the variation rules of the radon emanation coefficient in dump-leached uranium tailing sand. A temperature and humidity controllable device for measuring the emanation coefficient was designed. Tailing sand with different grain sizes was selected from uranium tailings in southern China. An orthogonal experimental design was conducted to determine the radon emanation coefficient of the sand under different temperatures, humidities and grain sizes. Experimental results showed that the air temperature, humidity and grain size have significant effects on the emanation coefficient. The variation rules regarding the radon emanation coefficient showed significant reference value. 相似文献
15.
A procedure first described by O. Hahn in 1935 has been adapted to the measurement of the probability of escape of radon and thoron//the emanation fraction/ in soils and rocks through application of the germanium counter. Measurement of the regrowth of the 214Pb, Bi, 212Pb, Bi and 208Tl following emanation loss permits the simultaneous determination of the two emanation fractions. 相似文献
16.
Radon activity concentrations of 1077 homes were surveyed in two villages of Northern Hungary to obtain the yearly averages. The distribution of indoor radon activity concentrations covered a wide range. Cancer incidences of all the 2680 inhabitants for the last 30 years were also studied in these villages in order to establish a possible correlation with radon exposure. The methods applied in the analysis allow to draw up statistically supported statements concerning the relative cancer risks of different radon level groups. The results show that among non-smoking middle-aged women the frequency of cancer, regardless to tumor types, is lower for those who live in residential radon activity concentrations of a level between 110 and 185 Bq .m -3 compared to those living in radon levels outside this range. A minimum value in the cancer frequency exists at a level of significance p<0.008 (determined with the help of Fisher's test). In general, the present study corroborates the outcome of other studies demonstrating the existence of a biopositive effect, and suggests a wider concept of radon health effects. 相似文献
17.
Summary Radon measurements were carried out in a Japanese wooden house built on granitic geology, where radon-rich well water is used.
Atmospheric radon concentrations were measured over one year with passive integrated radon monitors. The monitors were distributed
at several locations in the house and were replaced every two months. In order to confirm the diurnal variation and heterogeneous
distribution of radon, short-term measurements were carried out accordingly. Radon, its decay products and terrestrial gamma-radiations
were measured in this survey. From the long-term measurement, the radon concentration in the house ranged from 14 to 184 Bq . m -3with an arithmetic mean of 45 Bq . m -3. A radon concentration of 184 Bq . m -3was observed in the bathroom in spring (March-May) though the radon level was normal in the living room and bedroom. In order
to characterize the house, similar measurements were conducted in several surrounding houses. There was a significant difference
in radon concentration between the investigated houses. There was a spatial distribution of the radon concentration and the
highest value was found in the bathroom. Radon and its decay products concentrations varied with time, which increased from
midnight to morning whereas they decreased during daytime. Although the radon concentration in tap water was 1 Bq . l -1, a high level of 353 Bq . l -1was found in the well water.While well water was being used, the indoor radon concentration near the bathroom increased rapidly
with a maximum value of 964 Bq . m -3. It is clear that the use of well water enhanced the radon level around the bathroom. 相似文献
18.
Summary Radon measurements were performed across two sections of the Avila fault near Caracas, Venezuela. The radon concentrations
clearly showed the different tectonic features and lithology at the Tacamahaca and Spanish Trail sites. 214Bi (U-cps) measurements also were related to the lithology. The passive radon method employed laboratory-made dosimeters with
LR 115, type 2 celulose nitrate films as detectors. They were buried in the ground at 30 cm depth. While, the active radon
method was performed with a Pylon radon measurement system with Lucas cells. The soil gas was also sampled at 30 cm depths,
but for only one minute, which was sufficient to fill the 150 cm 3 Lucas cells completely. The total radon counts were then separated into those corresponding to 222Rn (radon) and 220Rn (thoron) by a simple computer routine. A comparison of the active and passive methods for the Tacamahaca section over a
three-month period showed that both methods could locate precisely the active fault trace. 相似文献
19.
Measurement of radon is of interest both for the health risk assessment and development of radon therapy in enclosed spaces
like as caves, mines and spas. In Romania, radon therapy is not in use, yet. The development of this treatment method in mines
from our country involves primarily, the evaluation of radon levels in the salt mines. In this paper, the results of radon
gas measurement that were performed at Ocna Dej salt mine (Romania) are presented. The radon measurements were performed using
two systems: radon monitor Pylon AB-5 system and CIS-P5M system. The average radon concentration was found to be between 9.14 ± 5.10 Bq/m 3 and 31.70 ± 2.76 Bq/m 3. These radon levels are lower in comparison to those reported for mines, caves or spas in other countries where radon therapy
and speleotherapy is frequently in use. Radon concentration and environmental conditions from Ocna Dej salt mine are suitable
for therapeutic applications. 相似文献
20.
Radon concentration was measured by using 39CR track etched detectors in five fertilizer warehouses in the Punjab province of Pakistan. The average concentration of radon was determined to be 20–88 Bq m−3. Annual effective dose (AED) and excess lifetime cancer risk (ELCR) have also been assessed using the models of UNSCEAR and ICRP. The corresponding annual dose and ELCR to the workers of warehouses have been estimated to be 0.30–1.02 mSv year−1 and 0.44–1.02%, respectively. 相似文献
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