Natural radioactivity in underground water from the Outer Carpathians in Poland with the use of nuclear spectrometry techniques

The investigations of natural radioactivity in underground mineral water and spring water in health resorts in the Outer Carpathians were performed. Samples from 40 water springs were collected 3–4 times over a period of 10 years (1997–2007). In order to obtain necessary data, two different nuclear spectrometry techniques were applied: WinSpectral α?β 1414 liquid scintillation counter from Wallac and α-spectrometer 7401 VR from Canberra–Packard, USA with the silicon surface barrier detector. The activity concentrations of ²²²Rn in the investigated samples varied from below 1 to 50 Bq/l. For radium isotopes the concentrations were in a range from below 10 to 490 mBq/l for ²²⁶Ra and from 29 to 397 mBq/l for ²²⁸Ra. The highest concentrations for both radium isotopes were obtained for medicinal water Zuber III from Krynica spa. The activity concentrations for uranium isotopes varied from below 0.5 to 16 mBq/l for ²³⁸U and from below 0.5 to 162 mBq/l for ²³⁴U with the highest values obtained for water Zuber IV. The highest annual effective dose arising from mainly radium isotopes was obtained for Zuber III water and was equal to 75 μSv/yr. Additionally, the annual effective doses due to ²²²Rn consumed with water were also estimated. The isotopic ratios between isotopes originating from the same decay chain (²³⁴U/²³⁸U, ²²⁶Ra/²³⁸U) and from different radioactive decay chains (²²⁶Ra/²²⁸Ra) were determined. The correlations between different isotopes were presented.     

Seasonal levels of radon and thoron in the dwellings along southern coastal Orissa,Eastern India

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.     

Radon-in-water standard

The radon-in-water standard installed at the Czech Metrology Institute in 1994 is based on a generator producing radium-free radon solution and on a measurement system for generator calibration and stability checking. The generator consists of about 6 L cylindrical vessel with a solid phase ²²²Rn source with 99.9% air emanation power and an external circuit for solution homogenisation. Standard solutions are prepared by charging water in the vessel with radon for an appropriate period; radon volume activity of the solution may vary from 300 to 2000 Bq/L; its uncertainty is less than 2.5%.     

High sensitivity radon emanation measurements

The presented radon detection technique employs miniaturized ultra-low background proportional counters. ²²²Rn samples are purified, mixed with a counting gas and filled into a counter using a special glass vacuum line. The absolute sensitivity of the system is estimated to be 40 μBq (20 ²²²Rn atoms). For emanation investigations two metal sealed stainless steel vessels and several glass vials are available. Taking into account their blank contributions, measurements at a minimum detectable activity of about 100 μBq can be performed.     

Determination of 222Rn in natural water samples from health resorts in the Sudety mountains by the liquid scintillation technique.

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.     

A new low-level γ-ray spectrometry system for environmental radioactivity at the underground laboratory Felsenkeller

A low-level γ-ray spectrometry system, based on an HPGe-detector with 92% relative efficiency recently installed in the underground laboratory Felsenkeller at 110 m water equivalent (w.e.) depth, is described. The integral background count rate normalised to the Ge-crystal mass in the energy range from 40 keV until 2.7 MeV of 0.034 s⁻¹ kg⁻¹ has been achieved by careful material selection of the detector construction material, a graded shielding construction and effective radon suppression. The detector is highly suitable for the effective surveillance of water for human consumption with decision thresholds for ²²⁶Ra and ²²⁸Ra in the order of some mBq L⁻¹.     

The 222Rn standard system established at IFIN-HH,Romania

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, T_1/2=(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.     

Indoor 222Rn measurements using an activated charcoal detector

A commercially available activated charcoal detector for measuring ²²²Rn activity concentrations in air was calibrated with known amounts of ²²²Rn and examined in terms of air luminescence counts and interferences from ²²⁰Rn and ²¹⁹Rn. The results for conditions normally encountered indoor indicate that the detector is simple and reliable. The method has been applied to assay indoor ²²²Rn activity concentrations in 387 homes in Tokyo and the adjacent four prefectures, which ranged from 0.7 to 140 Bq/m³ and averaged 22.7 Bq/m³.     

Radium-226 concentration in spring water sampled in high radon regions

Water ²²⁶Ra concentration in springs was measured in regions with high indoor radon: Ural, North Caucasus (Russia), Niska Banja (Serbia), Piestany (Slovakia), and Issyk-Kul (Kyrgyzstan). This paper presents the results for ²²⁶Ra concentration above 0.03 Bq l^–1. Radium in water could indicate indoor radon problem in the region and water investigation is useful at the initial stage of radon survey. Even low ²²⁶Ra concentration in water (0.1–0.6 Bq l^–1) caused high ²²⁶Ra activity in travertine (up to 1500 Bq kg^?1), which resulted in indoor radon concentration above 2000 Bq m^?3 (Niska Banja).     

222Rn, 226Ra and hydrochemistry in the Bauru Aquifer System,São José do Rio Preto (SP), Brazil

In this paper, the ²²²Rn and ²²⁶Ra activity concentration was measured in groundwater samples collected from the Bauru Aquifer System, São José do Rio Preto city, São Paulo State, Brazil. The site has been selected for a detailed radiometric survey due to the large number of tubular wells drilled in the aquifer there, which provide water for ~70% of the local population. Despite the importance of groundwater for the local water-supply system, there is a lack of both ²²²Rn and ²²⁶Ra data in the municipality. Establishment of these data is relevant to assure that the water quality from a radiological point of view, is not health threat. São José do Rio Preto city is geologically situated in Bauru Group that is located within the Paraná sedimentary basin. The monitoring program involved the collection of 50 groundwater samples from deep tubular wells during three field campaigns held from 17th to 19th January 2011, from 2nd to 3rd August 2011 and in 30th November 2011. Temperature and pH readings were realized in the field, whereas ²²²Rn and ²²⁶Ra analysis were performed at the laboratory using the Alpha Guard-Aquakit analytical protocol, which allowed us to obtain ²²²Rn activity concentration ranging from 0.69 to 14.95 Bq/L. These data indicate that the abundances of ²²²Rn and ²²⁶Ra in the groundwater system of Bauru Group is below the WHO guideline limit of 100 Bq/L. Chemical analysis has been also realized for major cations and anions in order to better understand the water features in the municipality.     

Passive,integrated measurement of radon using 5A synthetic zeolite and blue silica gel

Synthetic zeolite of 0.5 nm pore size (5A) and blue silica gel were tested to determine their capability to be used as radon collectors. Tests conducted in a radon chamber under controlled conditions of temperature and relative humidity indicate that simple, inexpensive and maintenance-free passive devices containing about 250 g of synthetic zeolite or about 270 g of blue silica gel in open face metal canisters that can measure radon conveniently and adequately, the latter though being suitable only for dry–medium dry atmosphere with quite high radon concentrations. Both materials can be recycled for reuse, in a way similar to the recycle and reuse of active carbon. The amount of radon adsorbed in such collectors is determined by counting the gamma rays from the radon decay products. The lower limit of detection (LLD) is estimated to ～45 Bqm^?3 for the synthetic zeolite and to ～350 Bqm^?3 for the blue silica gel, for an exposure of 48 h at a relative humidity of about 50%. In comparison, the corresponding LLD for active carbon is estimated to 10 Bqm^?3. At relative humidity in the range between 10% and 50%, radon chamber experiments indicate that the measured radon in the canisters is proportional to the mean concentration of radon during the period of exposure. It is estimated that calibration uncertainty lies within ±20% for both materials, thus suggesting that at least detectors based on the 5A synthetic zeolite presenting a reasonably low LLD, are a feasible and of similar cost alternative to activated carbon for indoors radon concentration measurements in practical situations.     

Full range determination of 222Rn at the watershed scale by liquid scintillation counting

²²²Rn has been increasingly used to identify groundwater contribution to surface water. Particular attention has been paid to analytical protocols and counting parameters used for liquid alpha scintillation measurements over a range of activities covering river and groundwater domains. Direct measurements and Rn-extraction protocols are optimized, and scintillometer efficiency is calibrated using international standards over the 0.5–35 Bq/L range. The interval of activities was performed in surface water and groundwater from a small Canadian watershed.     

Presence of a radioactive gas in archaeological excavations,determination and mitigation

During recent archaeological discovery and excavation of a tunnel build approximately 2000 years ago by the Teotihuacans under the feathered serpent temple, in Mexico, abnormal radon concentrations up to 700 Bq m⁻³ were measured at several excavation stages. The tunnel is at 15 m below the earth surface with a vertical rectangular entrance of 4×4 m², a semi cylindrical shape of 3 m in diameter, with a probable length of 100 m.This study supports the assumption that at the opening of the tunnel radon concentration was around 5500 Bq m⁻³; however, although natural convection in the tunnel atmosphere naturally pups radon out, it build up to a maximum concentration of 2000 Bq m⁻³. This paper presents the identification of the radon problem in this archaeological site, dose determination, and the mitigation actions that reduced the radon concentration down to 40 Bq m⁻³ that ensure a negligible radon risk for archaeologist.     

我国非铀矿山222Rn和220Rn水平初步调查研究

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。     

Mitigation of the effective dose of radon decay products through the use of an air cleaner in a dwelling in Okinawa,Japan

Field measurements were conducted to assess the effects of an air cleaner on radon mitigation in a dwelling with a high radon concentration in Okinawa, Japan. The measurements included indoor radon concentration, individual radon progeny concentration, equilibrium equivalent concentration of radon (EECRn), unattached fraction, and size distribution of aerosol-attached radon progeny. These measurements were conducted in a 74 m³ room with/without the use of an air cleaner. The results showed that the mean radon concentration during the measurement was quite high (301 Bq m⁻³). The operation of air cleaner decreased the radon progeny activity concentration, EECRn and equilibrium factor by 33%, 57% and 71%, respectively, whereas the unattached fraction increased by 174%. In addition, the activity concentration of attached radon progeny in the accumulation mode (50–2000 nm) was obviously deceased by 42%, when the air cleaner was operated. According to dosimetric calculations, the operation of air cleaner reduced the effective dose due to radon progeny by about 50%.     

Public exposure to radon in drinking water in SERBIA

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.     

Large-area low-level gross alpha ZnS scintillation counting

An efficiency of (44±2)% is achieved for samples placed directly on a 5 in diameter ZnS scintillator plate, placed on top of a 5 in photomultiplier in a light-tight pot. Background count rate is as low as (9±3) h⁻¹, equivalent to (5±2) mBq on 95 cm² for a second scintillator face to face or for a high-purity copper disk. Results are displayed continuously and printed on-line. An automatic repetition of measurements permits a measurement of activity as a function of time. From such a function radionuclides such as radon and its decay products may be distinguished from other radionuclides by their half-life in a technically simpler way than by their energy.     

Measurements of the Fe3+ diffusion coefficient in Fricke Xylenol gel using optical density measurements

In Fricke dosimetry, optical density measurements are performed some time after dosimeter irradiation. Values of the diffusion coefficient of Fe³⁺ in Fricke Xylenol gel (FXG) are necessary for determining the spatial distribution of the absorbed dose from measurements of the optical density. Five sets of FXG dosimeters, kept at different constant temperatures, were exposed to collimated 6 MV photons. The optical density profile, proportional to the Fe³⁺ concentration, at the boundary between irradiated and non-irradiated parts of each dosimeter was measured periodically over a period of 60 h. By comparing the experimental data with a function that accounts for the unobserved initial concentration profile of Fe³⁺ in the FXG, we obtained diffusion coefficients 0.30±0.05, 0.40±0.05, 0.50±0.05, 0.60±0.05 and 0.80±0.05 mm²/h for the temperatures 283.0±0.5, 286.0±0.5, 289.0±0.5, 292.0±0.5, and 296.0±0.5 K, respectively. The activation energy of Fe³⁺ diffusion in the gel, 0.54±0.06 eV, was determined from the temperature dependence of the diffusion coefficients.     

Variation of radon exposure in Damascus dwellings

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.     

Aluminium salt-based antiperspirant coated prosthesis liners do not suppress local sweating during moderate intensity exercise in hot and temperate conditions

ObjectiveTo determine whether coating prosthesis liners with a 5% aluminium zirconium tetrachlorohydrate antiperspirant solution (AZCH) reduces local sweating on the thigh.DesignDouble-blinded counter-balanced crossover designMethodsFourteen able-bodied participants (age: 28 ± 5 y; body mass: 73.9 ± 7.9 kg, height: 1.73 ± 0.09 m; peak oxygen consumption [VO_2peak]: 50.7 ± 9.1 mlO₂⋅ kg⁻¹⋅ min⁻¹) simultaneously wore a prosthesis liner on each leg, one treated with AZCH and one untreated, for four days prior to running at 50% of VO_2peak for 60 min in a temperate (23.7 ± 0.7 °C and 42.2 ± 2.6% relative humidity) or hot (34.0 ± 1.6 °C and 40.8 ± 6.1% relative humidity) environment. Rectal temperature (T_re) and whole-body sweat rates (WBSR) were measured to characterize thermal strain. Local sweat rate (LSR) was measured bilaterally underneath the liners, continuously, and heat-activated-sweat gland density (HASGD) was measured bilaterally every 15 min.ResultsIn temperate condition, the mean change in T_re was 1.2±0.4 °C and WBSR was 723 ± 129 g⋅ h⁻¹, whereas in the hot condition, change in T_re was 1.2±0.5 °C and WBSR was 911 ± 231 g⋅ h⁻¹. In the temperate condition, AZCH treatment did not alter LSR (treated: 0.50±0.17 mg·cm^–2 min^–1, untreated: 0.50±0.17 mg·cm^–2 min^–1; P = 0.87) or HASGD (treated: 54±14 glands·cm^–2, untreated 55±14 glands·cm^–2; P = 0.38). In the hot condition, AZCH treatment paradoxically increased LSR (treated: 0.88 ± 0.38 mg·cm^–2 min^–1, untreated: 0.74 ± 0.28 mg·cm^–2 min^–1; P = 0.04) but not HASGD (treated: 52 ± 17 glands·cm^–2, untreated: 48 ± 19 glands·cm^–2; P = 0.77).ConclusionThese results indicate coating prosthesis liners with 5% AZCH is ineffective at reducing local sweating.