A new method for determination of222Rn and220Rn in geothermal steam

The radionuclides²²²Rn and²²⁰Rn are measured by incorporating their daughters²¹⁴Pb and²¹²Pb in a very thin layer of PbS and accumulating the alpha spectrum of their daughter products²¹⁴Po and²¹²Po. The median yield was measured as 88% using a known amount of²¹⁰Pb tracer. A single fumarole and all 23 geothermal wells tested were found to contain²²⁰Rn. 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.     

Evaluating the potential alpha energy of radon progeny

Potential alpha energy concentration of radon progeny can be measured using the alpha-spectroscopy with the silicon semiconductors detectors and the gross-counting attached with the ZnS detectors. The decay method was applied where the alpha particles emitted from the ²¹⁸Po to ²¹⁴Po were detected. In the case of the decay products, the amount and aerodynamic behavior of radioactivity are important, and also need to be measured. During the experiment, the radon gas was supplied and evaluated from the experimental room with constant concentration. Then the air sample was used as the known volume and the grab sampling technique was developed for estimating the concentration of radon decay products. However the proper calculation was applied for estimating the potential alpha energy of radon progeny through of ²¹⁸Po, ²¹⁴Pb and ²¹⁴Bi.     

Determination of atmospheric lead-210 by alpha-scintillation counting of air filters

Alpha-counting of filters used to sample large volumes of air provides a convenient way of determining atmospheric concentrations of²¹⁰Pb. Following decay of short-lived²²²Rn and²²⁰Rn progeny, alpha activity of the filters increases as²¹⁰Pb decays to²¹⁰Po. After transient equilibrium is reached at about 3 y, alpha activity diminishes with the 22.3 y halflife of²¹⁰Pb. The degree of equilibrium between²¹⁰Pb and²¹⁰Po can be calculated subsequent to sampling, and the average concentration of²¹⁰Pb in the air during the sampling period can be computed. Contributions to the total²¹⁰Pb from ambient short-lived radon progeny are small, typically 2–4%. Using high volume air samplers with collection rates of 1.1–1.7 m³/min for 24 h periods, and using counting times of 2 h for 20 cm² filter sections, we measured alpha counts ranging from 0.0100±0.0050 to 0.200±0.0200 dps. Periodic measurements on 100 of these filters over a 4 y period yielded mean²¹⁰Pb levels with standard deviations less than ±15%. The method requires minimal sample preparation and can be used to determine past atmospheric²¹⁰Pb concentrations on filters stored for up to 20 y and more.     

Simultaneous determination method of radon-222 and radon-220 by a toluene extraction-liquid scintillation counter

A new determination method for²²²Rn and²²⁰Rn 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 of²²²Rn and²²⁰Rn was performed by counting the activity of²²⁰Rn 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 for²²²Rn and 6.8·10⁻⁸ Ci/l for²²⁰Rn in water.     

Field measurement of the <Superscript>218</Superscript>Po, <Superscript>214</Superscript>Pb and <Superscript>214</Superscript>Bi concentrations in typical indoor and outdoor environments in Beijing

The activity concentrations of ²¹⁸Po, ²¹⁴Pb and ²¹⁴Bi [i.e. C(²¹⁸Po), C(²¹⁴Pb), and C(²¹⁴Bi)] and the calculated concentration ratios [i.e. 1:C(²¹⁴Pb)/C(²¹⁸Po):C(²¹⁴Bi)/C(²¹⁸Po)] are necessary for assessing radon and its progenies exposure. In this study, a measurement method of radon progenies concentrations with both high sensitivity and low uncertainty, was developed based on the Kerr method. The field measurement results of radon progeny concentrations and calculated concentration ratios in both typical indoor and outdoor environments in Beijing, China, were reported. The effects of air exchange rate on concentration ratios of radon progenies in indoor environments were discussed.     

Comparative temporal behavior of radon- and thoron-progeny in surface air over the midwestern U.S.

Temporal variations in airborne²¹⁰Pb,²¹²Pb,²¹⁴Pb,²¹⁸Po, and²¹⁴Bi concentrations at Springfield, Missouri, USA, are compared with each other and with results reported from studies performed in other parts of the world. At Springfield diurnal concentration patterns of²¹⁰Pb are similar to those of²¹²Pb, but seasonal concentration patterns differ markedly. Additionally, abnormal disequilibrium conditions are sometimes found to exist in Springfield among²¹⁸Po,²¹⁴Pb, and²¹⁴Bi in which progeny/parent ratios are greater than 1. Findings similar to those presented here have been reported at some sites throughout the world, but different temporal patterns have been reported at others. Examination of concentration dependence on meteorological conditions at Springfield indicates that some of these differences are correlated with temperature and ground snow cover. Implications of these findings for use of thoron- and radon-progeny as atmospheric tracers are discussed.     

Determination of the distribution coefficients for134Cs,60Co and234Th in the Pinheiros River sediment-water

We have investigated the possibility of determining the relative concentrations of two radon isotopes (²²²Rn and²²⁰Rn) in the air, using solid state nuclear track detectors (CR-39) as alpha spectrometers. The detectors were exposed to²²²Rn and its daughters and²²⁰Rn 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.     

Simple collection and direct alpha-spectrometric determination of214Pb and214Bi in natural water

A rapid method has been developed for the de termination of²¹⁴Pb and²¹⁴Bi in natural waters by alpha-spectrometric measurement of²¹⁴Po. Well water was filtered on a membrane filter impregnated with manganese oxide and followed by direct alpha-spectrometric analysis. A prominent alpha peak was assigned to²¹⁴Po, which should be supported by the longer lived parents²¹⁴Pb and²¹⁴Bi. The activity ratios between²¹⁴Pb and²¹⁴Bi adsorbed on the filter were determined by using the change of activity of²¹⁴Po as a function of counting period after the filtration. The adsorbed yield of²¹⁴Pb was also determined from the growth of the alpha-peak due to²¹⁰Po from a²¹⁰Pb tracer added in the original water. The results indicated that the amount of²¹⁴Pb was in radioactive non-equilibrium state with the Rn-222 dissolved, while the activity ratios of²¹⁴Bi/²¹⁴Pb showed on increasing tendency with the storage period of the water.     

Possible correlation between uranium content in host rocks and radon and daughters concentration in air for two Italian ZnS-PbS mines

Research was carried out to evaluate the possible correlation between the uranium content in host rocks and the Rn and daughters concentration in air for two Italian ZnS-PbS mines. As a great variability had been ascertained for²²²Rn and daughters concentration in the different areas, it appeared of some interest to verify whether this fact was due to a different uranium concentration in the host dolomitic rocks or simply to a ventilation problem. Some rock samples were collected in several places where also radon and daughters were drawn; uranium was determined by fluorimetry and by alpha spectrometry after a chemical separation with a Microthene-TOPO column.²²²Rn was measured by the scintillation cell method, while the decay products were determined by the Markov and Tsivoglou methods. No correlation could be found between uranium content and radon concentration, but a good linearity was detected between the uranium content and the concentration of Rn decay products (alpha potential energy).     

Concentrations of radon,thoron and their decay products measured in natural caves and ancient mines by using solid state nuclear track detectors and resulting radiation dose to the members of the public

Alpha- and beta-activities per unit volume of air due to radon (²²²Rn), thoron (²²⁰Rn) and their progenies were measured in the air of natural caves and ancient mines as well as inside different reference atmospheres by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). In addition, the radon concentration was continuously measured inside one of the studied caves by using the SSNTDs’ method and AlphaGuard counter. Equilibrium factors between radon and its daughters and between thoron and its progeny were evaluated in the studied atmospheres. Alpha-activities due to ²¹⁸Po and ²¹⁴Po short-lived radon decay products were determined in different compartments of the respiratory tract of members of the public. The committed equivalent doses due to the ²¹⁸Po and ²¹⁴Po radon short-lived progeny were evaluated in different tissues of the respiratory tract of the visitors of the considered caves and ancient mines. Annual effective doses due to radon progeny from the inhalation of air by the visitors of the studied caves and ancient mines were evaluated.     

Radiochemical separation of bismuth activities using Dalzin,and its application to geological problems

A radiochemical method has been devised for the separation of bismuth activities of the natural series,viz.²¹⁴Bi,²¹⁰Bi and²¹²Bi, and applied to the indirect estimation of their corresponding precursors,²²²Rn,²¹⁰Pb and²¹²Pb, in a wide variety of geological materials. The method consists of the solvent extraction of bismuth in radiochemically pure form from the sample solution atpH 2 with diallyldithiocarbamido-hydrazine (Dalzin) in chloroform, and back extraction with 2M acid. The advantages of this method over the dithizone extraction system are discussed.     

Measurement of radon in air by α track method enhancement of detection sensitivity using a lamp

A new α track method is proposed for the measurement of radon (²²²Rn) concentration in environmental levels. This involves collecting radon daughters on the surface of pilot lamp and detecting α-particles emitted from the nuclides (²¹⁸Po and²¹⁴Po) by a detector (LR 115). The detection sensitivity of this method is 6 times greater than that of the conventional α track method.     

Radon in the spa of Bizovac

The radon concentration in the air and water of the Bizovac spa was measured by the Radhome silicon detector and the average values were obtained as 70 Bq/m³ in the indoor pool, 40 Bq/m³ in the hotel room, 135 Bq/m³ in the closed therapeutic bathroom, but the geothermal water had a Rn concentration of 25.3 kBq/m³ and the potable one 2.7 kBq/m³. The Rn transfer factor (f) from water to air in the indoor pool and therapeutic bathroom was 10 and 40 times higher than for normal dwellings (f _n=10^–4), respectively. The effective equivalent dose of inhaled radon for permanent personnel under the worst conditions in the spa was 5.4 mSv/y, but visitors spending two weeks in the spa could receive the dose of 77 Sv.     

Fast determination of indoor radon (<Superscript>222</Superscript>Rn) concentration using liquid scintillation counting

The indoor ²²²Rn radionuclide was directly absorbed in typical 20 ml glass scintillation vials by passing ?3 dm³ of ambient air through 16 ml of water-immiscible non-volataile scintillation cocktail Ultima-Gold F for 10 min. The activity of radon and its two α-emitting daughters: ²¹⁸Po and ²¹⁴Po, was determined with the BetaScout low-background liquid scintillation counter. The limit of ²²²Rn detection is 9 Bq/m³, and the quantification limit with 20% relative accuracy is 28 Bq/m³. The results of the indoor Rn measurement in different houses showed good consistency with results obtained from a Sarad EQF 3220 device.     

222Rn determination in drinkable waters of a central eastern Italian area: Comparison between liquid scintillation and gamma-spectrometry

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.     

Use of the Sorben-Tec system for rapid dosimetric evaluation of <Superscript>222</Superscript>Rn level in drinking water

The Sorben-Tec system was tested for rapid dosimetric evaluation of ²²²Rn level in drinking water in domestic conditions using a dosimeter of beta radiometer as a measurement equipment. It was shown that the method is cheap, rapid and very simple, therefore it can be used by population for rapid radiation safety assessment of drinking water. The sorption-active Sorben-Tec system contains iron hexacyanoferrate allowing for separation of approximately 40% of both ²¹⁴Pb and ²¹⁴Bi, the short-lived decay products of ²²²Rn from 5 L water sample. It was assessed that the Sorben-Tec system provides detection limits of radon in 5 L water samples of 35–40 and 10 Bq L^?1 for dosimetric and radiometric measurements respectively. The total time consumption of analysis does not exceed 1 h excluding the time for ²¹⁴Pb and ²¹⁴Bi ingrowth in the water sample (min. 3 h). Due to an insignificant sorption of radon, it is possible to reuse spent Sorben-Tec system again 3–4 h after previous analysis.     

Detection efficiency improvement of a large volume scintillation cell

A large volume scintillation cell (LVSC) for radon activity concentration measurements has been reported at MARC-IV. The present paper describes improvements in the detection efficiency of the LVSC and results of the radon activity concentration measurements for indoor air that were performed using the improved LVSC. The cell is a cylindrical shape and has two photomultiplier tubes that are attached to a condensing lens on the photocathode so as to provide good light collection. Individual counting efficiencies were determined to be 0.48 for ²²²Rn, 0.55 for ²¹⁸Po, and 0.61 for ²¹⁴Po. The average counting efficiency per alpha-particle from the radon and its short half-life progenies was 0.55. This value is smaller than the original value reported by LUCAS of 0.86. However, the sensitivity is approximately eight times higher than that of the Lucas cell, which has a smaller volume. A background counting rate of 0.015 cps was obtained. The lower limit of detection (LLD) for the measurements was estimated using the average background counts, the detection efficiency and measurement time. The LLD at 80% statistics confidence limits was less than 10 Bq/m³ when counted within two hours.     

Indoor radon measurement in Izmir Province,Turkey

In 2013, an extensive study was performed in a total of 117 locations in Izmir province and indoor radon levels were measured using the alpha track etch integrated method with LR-115 detectors. As the maps are more practical to interpret the results of radiological survey, the distributions of indoor ²²²Rn activities in four most densely populated districts of Izmir were mapped in detail. It is seen that the estimated average radon concentration level (210 Bq m^?3) determined in Izmir province was almost three times higher than the mean value for Turkey (81 Bq m^?3). Exposed annual effective dose equivalents for Izmir province were estimated in the range of 0.7 to 12.3 mSv year^?1 with a mean of 5.3 mSv year^?1. In this study, it is pointed out that indoor radon concentration was affected by the age of the building and height above the ground.     

A continuous monitor for assessment of 222Rn in the coastal ocean

Radon-222 is a good natural tracer of groundwater flow into the coastalocean. Unfortunately, its usefulness is limited by the time consuming natureof collecting individual samples and traditional analysis schemes. We demonstratehere an automated system which can determine, on a continuousbasis, the radon activity in coastal ocean waters. The system analyses ²²²Rn from a constant stream of water passing through an air-water exchangerthat distributes radon from the running flow of water to a closed air loop.The air stream is feed to a commercial radon-in-air monitor which determinesthe concentration of ²²²Rn by collection and measurement of theemitting daughters, ²¹⁴Po and ²¹⁸Po, via a charged semiconductordetector. Since the distribution of radon at equilibrium between the air andwater phases is governed by a well-known temperature dependence, the radonconcentration in the water is easily calculated.     

The simultaneous determination of the emanation fractions of radon and thoron

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 the²¹⁴Pb, Bi,²¹²Pb, Bi and²⁰⁸Tl following emanation loss permits the simultaneous determination of the two emanation fractions.