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1.
An intercomparison on radon ((222)Rn) measuring instruments was carried out at the Physikalisch Technische Bundesanstalt, Germany (PTB). Two types of alpha track detectors based on a passive (222)Rn-thoron ((220)Rn) discriminative measurement technique were used: these were the commercially available Raduet and Radopot detectors that were developed and calibrated by the National Institute of Radiological Sciences, Japan (NIRS). The (222)Rn grab sampling and continuous measurement methods were also compared using the PTB pulse ionization chamber. The results using the passive detectors showed that there was a good agreement between the time-integrated (222)Rn concentrations obtained from the Raduet detectors and the PTB pulse ionization chamber, as in the case with the Radopot detectors. In the grab sampling measurements, the agreement between the (222)Rn concentrations measured using the NIRS gas storage ionization chamber and the PTB pulse ionization chamber was within 5% as in the case with the NIRS scintillation cell measurement. Similar to the measurements of the passive detectors and grab sampling, little distinct difference in the (222)Rn concentration was observed for the NIRS continuous electrostatic collection monitor. 相似文献
2.
目的:为了解环境氡的变化规律和对人体的影响,从1988年11月至1993年3月,中日合作对我国人口密集的10个城市的室内外222Rn浓度进行了现场调查。方法:使用日本名古屋大学研制的Aloka,Cs-201B型静电累积222Rn探测器。该仪器采样2个月时,探测下限为0,4Bq·m-3。结果:室外10个城市年平均值为8.8Bq·M-3,其中武汉市为最高(13.5Bq·m-3·a-1),上海的崇明岛最低(3.3Bq·m-3·a-1)。在西北风的季节里,台湾地区室外222Rn浓度的50%由陆地气团所贡献。室内10个城市年平均值为19.5Bq·m-3,其中贵阳市最高(33.9Bq·m-3·a-1),上海的崇明岛最低(9.0Bq·m-3·a-1)。10个城市由222Rn及其子体所致公众年平均当量剂量为0.64mSv·a-1,其中贵阳市最高(1.12mSv·a-1),南通市最低(0.39mSv·a-1)。结论:以上结果表明,所调查的10个城市室内222Rn的平均浓度值低于世界均值,222Rn及子体所致居民的平均剂量也低于世界均值。 相似文献
3.
Ferdoas S Al-Saleh 《Applied radiation and isotopes》2007,65(7):843-848
Indoor gamma radiation measurement at dwellings of Riyadh city in Saudi Arabia using TLD has been performed. Measurements were carried out from October 2004 to June 2005. The city was divided into five sectors, for four categories of bed rooms, living rooms, bathrooms and kitchens. The indoor gamma annual absorbed dose of Riyadh city is in the range from 303+/-57 to 700+/-38microGyy(-1) with an average value of 455.1+/-45microGyy(-1). The calculated corresponding annual effective dose to the adult population of the locations will vary from 212+/-40 to 490+/-27microSvy(-1) with an average value of 318.57+/-31microSvy(-1).(222)Rn concentration was measured at dwellings of Riyadh city in Saudi Arabia to estimate effective annual dose to the public from (222)Rn and its progeny. The (222)Rn concentrations were measured using CR-39 detector. The range of annual mean (222)Rn concentrations for all sites was 2-69Bqm(-3) with an average of 18.4Bqm(-3). The effective annual dose was estimated to be 0.46mSvy(-1). 相似文献
4.
《Applied radiation and isotopes》2009,67(1):178-185
Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of solid-state nuclear track detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil–gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites. 相似文献
5.
Inhalation of radon (222Rn) and thoron (220Rn) are a major source of natural radiation exposure. Indoor radon–thoron study has been carried out in some dwellings of Ganjam district, southern coastal Orissa, India using LR-115 type II plastic track detectors. Seasonal variation of indoor radon and thoron shows high values in winter and low values in both summer and rainy. The inhalation dose lies in the range of 0–0.06 μSv h?1 and is not high from those found elsewhere in India. 相似文献
6.
Shweikani R 《Applied radiation and isotopes》2012,70(4):785-789
In the present work, activity concentrations of 222Rn in air and 222Rn and 226Ra in drinking water were measured in Damascus city covering its old and modern parts.It was found that the average air radon activity concentration in the old part was higher than in the modern part, and in drinking water, radon was found to be 60±3 Bq/l, and less than 0.13 Bq/l for radium, which were lower than the recommended levels set by WHO. 相似文献
7.
L L Quirino J M Soriano F Mireles J I Dávila H López J L Pinedo C Rios 《Applied radiation and isotopes》2007,65(3):371-374
As part of a program for discovering whether afflicted areas exist, indoor (222)Rn concentrations in the State of Zacatecas were surveyed, (222)Rn concentration being measured by gamma-ray spectrometry of radon decay products adsorbed into charcoal canisters. A survey was implemented during Summer 2001: 228 dwellings in the state were tested by taking mean 254 measurements. Concentrations exhibited a left-skewed distribution of indoor (222)Rn, showing overall average, minimum, and maximum concentrations of 67, 26, and 511 Bqm(-3), respectively. Only seven of the measurements (2.7%) were found equal to or greater than the US EPA action limit (148 Bqm(-3)). Thus, we conclude that the indoor radon environment in Zacatecas State is under US EPA action limit. The few high concentration spots suggest that geological conditions rather than construction materials may be the determinant factor. 相似文献
8.
Laureano-Perez L Collé R Jacobson DR Fitzgerald R Khan NS Dmochowski IJ 《Applied radiation and isotopes》2012,70(9):1997-2001
In collaboration with the University of Pennsylvania, a (222)Rn emanation source was used for the determination of the binding affinity of radon to a cryptophane molecular host. This source was similar to a (222)Rn emanation standard that was developed and disseminated by the National Institute of Standards and Technology (NIST). The novel experimental design involved performing the reactions at femtomole levels, developing exacting gravimetric sampling methods and making precise (222)Rn assays by liquid scintillation counting. A cryptophane-radon association constant was determined, K(A)=(49,000±12,000) L mol(-1) at 293 K, which was the first measurement of radon binding to a molecular host. 相似文献
9.
Studies of radon isotope 222Rn activity concentration in underground water in the Sudety region were performed with the use of the liquid scintillation technique. Waters chosen for investigations were collected in 24 health resorts and towns of the Sudety area from 115 springs, wells and intakes. The 222Rn activity concentration varied within the range from 4.2±0.4 to 1703±55 Bq/l. The annual effective doses due to the consumption of 222Rn with water were calculated for 50 sources of underground spring water or tap water used for consumption. The results were within the range from 0.003 to 1.1 mSv/yr, assuming 0.5 l of tap water per day from which radon is not removed or 0.5 l of mineral spring water consumed daily. The contribution to the effective dose from the inhalation of radon during the daily usage of domestic water substantially increases its effective dose. 相似文献
10.
目的 测量非铀矿山222Rn、220Rn水平,了解我国矿山氡超标比率和矿工受照剂量。方法 根据典型抽样方法选择12个省17类44座矿山,采用LD-P分辨型探测器测量222Rn、220Rn累积浓度。结果 222Rn、220Rn浓度呈对数正态分布,金属矿(25座,147处)222Rn浓度算数均值(AM)和几何均值(GM)分别为(1211±2359)和(311±5.5) Bq m3;220Rn浓度AM和GM分别为(269±700)和(71±4.4) Bq m3。非金属矿(18座,118处)222Rn浓度AM和GM分别为(98±207)和(55±2.5) Bq m3;220Rn浓度AM和GM分别为(60±76)和(38±2.4) Bq m3。测量地下矿井40处,其中6处222Rn浓度均值超过1000 Bq m3 (工作场所氡浓度限值),占抽样率15.0%;约有7%测点222Rn超过浓度3700 Bq m3 (我国铀矿冶氡浓度限值),个别测点超过10 000 Bq m3。井下和地面工作区室内222Rn平衡因子分别为0.33±0.15和0.47±0.18。220Rn平衡因子的波动范围较大,为0.001~0.032。地下矿山矿工的年均受照剂量约为8.15mSv。结论 我国金属矿山特别是有色金属矿井下222Rn浓度偏高的问题依然严重,值得关注和进行跟踪研究。 相似文献
11.
目的 调查山东省典型非铀矿山井下222Rn浓度并估算矿工接受年有效剂量。方法 利用固体径迹探测器CR-39累积测量金矿、铁矿、煤矿井下220Rn、222Rn浓度,利用高纯锗γ谱仪分析矿石226Ra、232Th、40K活度浓度。结果 山东非铀矿山井下220Rn浓度平均值由高到低依次为金矿、铁矿、煤矿、黏土矿,分别为1200、280、120和40 Bq/m3;煤矿、金矿、黏土矿和铁矿的226Ra、232Th、40K活度浓度基本处于我国土壤天然放射性核素浓度范围内;222Rn及其子体所致井下矿工年有效剂量,金矿最高为7.7 mSv,铁矿次之,为1.7 mSv,煤矿和黏土矿均低于1 mSv。结论 金矿和铁矿应采取加大通风能力等措施降低井下氡浓度,井下矿工应该作为职业照射人员进行管理。 相似文献
12.
Drying soil samples in an oven to remove water alters the 222Rn emanation rate. Measurements of the oven drying 222Rn emanation rate from soil were made with a continuous radon monitor and the degree of 222Rn disequilibrium was quantified by laboratory gamma-ray spectroscopy. This paper presents a disequilibrium correction where the 226Ra activity in oven-dried soil samples is inferred from immediate laboratory gamma-ray spectroscopy of 214Bi before 222Rn and its decay progeny reach secular equilibrium. 相似文献
13.
Todorovic N Nikolov J Forkapic S Bikit I Mrdja D Krmar M Veskovic M 《Applied radiation and isotopes》2012,70(3):543-549
Radon is the main source of natural radiation that is received by population. The results of radon activity measurements in water from public drinking fountain, from bottled drinking water and from tap water in the city of Novi Sad, Serbia, are presented in this paper. The measurements were performed by RAD 7 radon detector manufactured by DURRIDGE COMPANY Inc. The corrected value of radon concentration in one sample exceeded the European Commission recommendation reference level for radon in drinking water of 100 Bq l−1. In order to make the correlation between radon and radium concentrations in the tap water and in the water from public drinking fountain, the gamma-spectrometric measurements were performed. The results of 222Rn activity concentration measurements from soil in the city of Novi Sad using RAD 7 detector are presented. 相似文献
14.
Two methods for measuring 222Rn exhalation and effective 226Ra in soil samples were studied. In the first determination, the method employed was based on the adsorption of radon onto activated charcoal and subsequent measurement of the activity of its daughters with an HPGe (high-purity germanium) detector. In the second, vials containing an aqueous suspension of the sample, mixed with an insoluble high efficiency mineral oil scintillation cocktail, were measured using a low-level liquid scintillation counter. Studies of optimum sampling time, efficiency in both procedures, variation of 226Ra efficiency with quenching, as well as the effect of sample amount and granulometry upon the quenching parameter, were carried out. The two methods were applied to the determination of 222Rn exhalation and effective 226Ra in environmental samples. 相似文献
15.
R Dersch 《Applied radiation and isotopes》2004,60(2-4):387-390
In the past few years, a primary measurement system has been established at the PTB allowing absolute measurements of 222Rn. The activity can be determined by counting the emitted alpha particles in a defined solid angle after condensing the radon at a cold point under vacuum conditions. This primary measurement system is connected to a solid 226Ra source, where 222Rn can be produced up to an activity of about 2MBq. After the measurement, radon can be completely transferred into a glass bulb or a stainless steel cylinder for use as a transfer standard. The results of the measurements, the uncertainties and the realization of the primary measurement system are described. For quality assurance and fast determination of radon activity, a secondary measurement system with an NaI(Tl) detector is also used. Together, both systems provide a reliable tool for the production of gaseous 222Rn activity standards with relative uncertainties of less than 1%. 相似文献
16.
Determination of 222Rn in natural water samples from health resorts in the Sudety mountains by the liquid scintillation technique. 总被引:1,自引:0,他引:1
A method involving a Wallac 1414 WinSpectral alpha/beta liquid scintillation counter for determining 222Rn in aqueous samples is described. Samples were collected from 23 springs and 4 taps in health resorts of the Klodzka valley in the Sudety mountains in Poland. Half of the investigated spring water samples were radon enriched with an activity concentration higher than 74 Bq/l. In the tap waters the radon concentration level is very low or below the lower limit of detection. Owing to the statistical nature of radioactive decay the uncertainty of the measurement was determined as the standard deviation of 222Rn activity. The method introduced is fast and simple and does not require a chemical sample preparation procedure. 相似文献
17.
E. Garca D. González A. Morales J. Morales A. Ortiz de Solórzano J. Puimedón C. Sáenz A. Salinas M.L. Sarsa J.A. Villar 《Applied radiation and isotopes》1998,49(12):23
The contribution of 222Rn to the background in a low background experiment with a germanium detector has been estimated. We have also checked the efficacy of a standard radon cleaning system. The cleaning reduces the radon concentration two orders of magnitude with respect to the air in the laboratory. The residual 222Rn represents at most 12.5% of the background in the low energy region, a value low enough for the purpose of our experiment. A detailed study of the radioactive background is presented. 相似文献
18.
A method to determine simultaneously the rates of 222Rn and 220Rn released from building materials quarried in Central Italy is presented. The method makes use of a continuous monitor equipped with a solid state alpha detector, in-line connected to a small accumulation chamber. The effects of chamber leakage and back diffusion on 222Rn free exhalation rate is evaluated. The influence of available exhalation surface, humidity content and precursors concentration on radon and thoron exhalation rates is investigated. 相似文献
19.
M. Sahagia D. Stanga A.C. Wätjen A. Luca P. Cassette C. Ivan A. Antohe 《Applied radiation and isotopes》2010,68(7-8):1503-1506
The paper presents the 222Rn Standard System realized at the Radionuclide Metrology Laboratory from IFIN-HH, Romania. It contains a Pylon solid 226Ra source, and a glass circuit for circulation and recovery of 222Rn in glass ampoules, at the 77 K temperature. The radon can be recovered both in ampoules with liquid scintillator (LS), for absolute standardization of 222Rn by liquid scintillation counting (LSC) (Cassette et al., 2006), and in evacuated ampoules as gas, simultaneously or by the transfer of radon from gas into LS ampoules, in order to establish the traceability chain. The absolute standardization consists in the registration of the double coincidence counting rate in LS, due to the whole sequence of short life components of the 222Rn chain, in equilibrium conditions. The main correction applied to the measurement results is due to the decay of 214Po during the extendable dead time of the system. The following procedure was applied to take it into account. The value of the base duration of the dead time was precisely measured and used for the data corrections. The measurements of each source were repeated during a period of several days, and the decay curve parameters were calculated. If the dead time value and the correction formulae, presented throughout the paper, were adequate, then the re-determination of the 222Rn half life, T1/2=(3.8232±0.0008) d, using the decay curve of the corrected counting rates should be correct. On the other hand, the effective dead time values obtained by parallel calculations were compared. The paper presents the results obtained in the standardization of several sources, by LSC, and the evaluation of the uncertainties associated to the method. 相似文献
20.
Richard B. Richardson 《International journal of radiation biology》2013,89(10):838-848
Purpose: There is mounting evidence that a significant fraction of radiation-induced mortality and years-life lost are non-cancerous in nature. This study quantifies the radon dose to the coronary artery walls, especially the intimal layer, vunerable to the development of atherosclerosis, and associated cardiovascular disease (CVD). Two accompanying papers determine the oxygen levels (Part B) in coronary arteries and the oxygen effect for radon and other exposures (Part C).Materials and methods: The alpha-radiation dose to coronary artery walls was calculated from the proportion of inhaled radon (222Rn), thoron (220Rn) and their short-lived progeny, which was not deposited in the lung and passed into blood. Age- and gender-dependent morphology and composition for the wall layers of coronary arteries were developed from published data for a normal population and also for individuals with cardiovascular disease. The alpha particle dose to the coronary artery walls was evaluated taking account the diffusion of radon from blood and the solubility of radon-gas in tissues.Results: Diseased arteries exhibited a moderate increase in the solubility of lipophylic radon (190%) in arteries with 88% luminal narrowing, as the high Rn solubility in fat was partially offset by the lower solubility in calcium deposits. The average worldwide dose rate to the diseased intimal layer from 222Rn and its short-lived progeny was estimated to be as high as 68 μSv y?1 per 40 Bq m?3 in air, whereas the corresponding dose rate from 220Rn per 0.3 Bq m?3 in air was ≤0.1% in comparison. Gender had little influence on the dose.Conclusion: The Rn dose to the coronary arteries is significant, but has a large uncertainty due to poor knowledge of Rn and its progeny concentrations in the body. 相似文献