222Rn radioactivity in urban waters of fault zone in China: dose rate and risk assessment

Journal of Radioanalytical and Nuclear Chemistry - The exhalation of radon from waters surrounding active fault zones is at present not well understood. In this work, radon concentrations in urban...     

238U and 222Rn activity concentrations and total radioactivity levels in lake waters

The concentrations and distributions of natural radioactivity, uranium and radon in lake waters from around Van, Turkey were investigated with an aim of evaluating the environmental radioactivity. Fourteen lake waters were collected from different six lakes around Van (Turkey) to determine ²³⁸U, ²²²Rn and total alpha and total beta distributions in 2009. The total α and total β activities were counted by using α/β counter of the multi-detector low background system (PIC-MPC-9604) and the ²³⁸U concentrations were determined by inductively coupled plasma-mass spectrometry (Thermo Scientific Element 2) and radon concentrations were measured with the solid state nuclear track detector technique. The activity concentrations ranging from ND to 0.039 Bq L^?1 and from 0.026 to 3.728 Bq L^?1 for total alpha and beta, respectively, and uranium concentrations ranging from 0.083 to 3.078 μg L^?1, and radon concentrations varying between 47.80 and 354.86 Bq m^?3 were observed in the lake waters.     

A simple technique for surface labeling of solids with222Rn and its short-lived decay products

A simple radioactive labeling technique is described which is based on a recoil injection of atoms of²²²Rn and its decay products from a²²⁶Ra source into thin surface layers of solids.     

Enrichment of sea-salt aerosols in short-lived222Rn daughter products-role of marine Fe/III/ hydroxide colloid

The interaction of short-lived Rn-daughter products /SLDP/, viz.²¹⁴Pb and²¹⁴Bi dissolved in sea-water with Fe/III/ hydroxide colloids followed by flotation of combined Fe-SLDP particles at the sea-air interface subsequently generating marine aerosols enriched in²¹⁴Bi and²¹⁴Pb have been studied under laboratory conditions. Rate constants for attachment of²¹⁴Bi and²¹⁴Pb to dispersed Fe/III/ colloids in the sea water are found to be 3.7×10^–4 min^–1 litre [g/Fe/]^–1 and 2.4×10^–4 min^–1 litre [g/Fe/]^–1, resp., /20°C/ over the concentration range of iron /III/ from 8 to 120 g liter^–1. The suggested mechanism of colloid flotation and aerosol generation might be responsible for some peculiarities of SLDP distribution in the lower marine atmosphere.     

Analysis of radon-222 daughters in air

Common formula for radon-222 short-lived daughter concentration by total -counting and spectrometric method is detailed in this paper. A computer program has been written, and two procedure errors in references are pointed out. Some coefficients have been corrected and supplemented, and the corresponding formulas in SI units are given. The thoron daughters can be dealt with in the same way.     

Measurements of222Rn migration in soil

The concentration of radon (²²²Rn) was measured in the soil near the ground surface, using CR/39 solid state nuclear track detectors. The measurements were carried out in PVC tubes at 0.25 m intervals up to 1.25 m. The detectors were etched in 7N NaOH solutions at 80°C. The -tracks from radon's decay were counted using a microscope. A microscope-camera-computer system developed for automatic counting was also used. The results provide evidence for the non-diffusive transport of radon in soils. A transport length of (46.9±3.2) cm was estimated for radon transport near ground surface. Also the variation of soil's radon concentration was correlate to humidity and atmospheric pressure.     

Background of low-level gamma-ray spectrometer due to the atmospheric 220Rn and 222Rn

In connection with low-level gamma-ray counting of natural samples, background due to 220Rn- and 222Rn-daughters was monitored. The results obtained for 4 months showed that the background gamma-ray from 222Rn-daughters was more variable than that of 220Rn-daughters. An efficient air-conditioning was helpful to keep the background stable. It was practically equivalent to the use of N2-gas. Radiometric data for dust samples filtered from the laboratory air suggested that Rn-daughters tended to be removed by air-conditioning.     

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.     

A survey of 222Rn concentrations in dwellings of Turkey

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.     

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.     

Effect of cigarette smoke on the measured equivalent volume activity of222Rn in air

The effect of cigarette smoke in air on the increase of the measured equivalent volume activity of²²²Rn is demonstrated. After introduction of the smoke from one cigarette into 1 m³ of air, this value increased up to ten times as shown by the method of sucking air through a filter.     

Comparison of three methods for measuring 222Rn in drinking water

Three techniques were used to measure ²²²Rn in drinking water: the degassing method followed by counting in an ionisation chamber (IC); gamma spectrometry (GS); and liquid scintillation counting (LSC). Environmental samples were measured in the field using the IC, and the same samples were measured in the laboratory using GS and LSC. The results obtained using the three techniques are compared and discussed in the context of the new Euratom Drinking Water Directive (2013/51/Euratom), which sets out general principles for monitoring radioactive substances such as radon.

     

Measurement of the Unattached Fraction of 222Rn Progeny Using Wire Screens

A method for the measurement of the unattached radon progeny based on the electrostatic deposition on wire screens has been implemented and calibrated, using only one sampling pump. The importance of being able to measure the short-lived radon progeny resides in the special radiological significance that the unattached fraction has. It was possible to apply this measurement method to several dwellings of Argentina and then, have an estimated value of the unattached fraction under different aerosol source conditions. The remarkable aspect of this method is its simplicity, not only in the sample collection equipment used, but also in the measurement instruments, as well as the counting protocols that are simple and fast.     

222Rn gas diffusion and determination of its adsorption coefficient on activated charcoal

The adsorption coefficient is the fundamental parameter characterizing activated charcoal"s ability to adsorb ²²²Rn. The adsorption coefficient is determined for ²²²Rn activated charcoal detectors. In addition, a diffusion and adsorption model is developed for the transport of ²²²Rn in a porous bed of activated charcoal. These processes can be described by parabolic second order differential equation. The equation is numerically solved using the finite differences method. With this model, the ²²²Rn activity adsorbed in the detector is calculated for diverse situations.     

Application of ultra-low level liquid scintillation to the determination of 222Rn in groundwater

A procedure for the determination of ²²²Rn in environmental water samples using liquid scintillation counting (LSC) was applied. The extractive scintillator RADONS^Ò and an ultra-low background 1220 QuantulusÔ were used. A minimum detectable activity of 0.1 Bq·l^?1 in 20 ml was found with low-diffusion polyethylene vials and 200 minute measurement time. Quenching effects and possible interferences due to the existence of other radionuclides in the extraction process were studied. The procedure was controlled by gamma-ray spectrometry of the ²²²Rn daughters. Applications to environmental samples collected from spas, wells, and public springs in Extremadura (Spain) are presented.     

Time variation of radon daughters concentration in snowfall

Time variation of radon daughters concentration in snowfall was measured continuously. The relations of radon daughters concentration in snowfall to the precipitation and to atmospheric radon daughters concentration were investigated. It has become clear that when precipitation is small, radon daughters concentration in snowfall is distributed in a wide range, and that the quantity of radon daughters brought to ground surface by snowfall is proportional to precipitation. Washout effect of the snowfall on atmospheric radon daughters was also investigated.     

Determination of 222Rn in Iranian mineral waters using liquid scintillation alpha-spectrometry

Liquid scintillation counting (LSC) method has been used for the measurement of ²²²Rn in mineral water samples under a pilot project for the first surveillance in Iran. Low level background LSC counter Quantulus and pulse-shape analysis method have been employed. The concentration of ²²²Rn found in mineral waters of the studied areas ranges from about 1 to 75 Bq/l. The best lower limit of detection obtained with the applied technique was 0.069 Bq/l for a counting time in the range of 236–296 minutes.     

222Rn determination in some thermal baths of a central eastern Italian area

Some recent Italian laws, based on the Euratom Directive 26/96, introduce the obligation of monitoring the exposition to natural radioactivity in particular worksites (thermal baths, mines, basements, etc.). This paper reports the results of ²²²Rn measurements in some thermal baths of Rimini and Pesaro-Urbino provinces (Central Eastern Italy), by Radosys-2000, a complete set suitable to radon concentration measurements with CR-39 plastic alpha-track detectors. Some areas where radon could accumulate (bathing, reaction, muddy, inhalation, insufflation rooms and swimming pools) were selected for the investigation. The dosimeters have been exposed for 98 days. The results show that ²²²Rn concentrations are very low in the considered thermal baths (7-71 Bq^.m^-3). Moreover, no difference was observed between the concentrations measured in the therapy rooms (bathing, muddy, inhalation and insufflation rooms, swimming pools) and in the normal areas (passages, reaction rooms, dressing rooms, etc.). The calculated dose contribution to workers was about one tenth of the legally suggested value. This revised version was published online in July 2006 with corrections to the Cover Date.     

A 15-year record of seasonal variation in the isotopic composition of precipitation water over continental Portugal

The Nuclear and Technological Institute (Instituto Tecnológico e Nuclear—ITN) in cooperation with the International Atomic Energy Agency (IAEA) has been conducting a nationwide survey of hydrogen (²H/¹H) and oxygen (¹⁸O/¹⁶O) isotopic composition of monthly precipitation since 1988. This paper focuses on basic features of spatial and temporal distribution of δ¹⁸O and δ²H in the precipitation over Continental Portugal derived from ITN database. Phenomenological relationships between stable isotopes composition of precipitation and various climate-related parameters (local air temperature, distance to the Atlantic coast, altitude, amount of precipitation) are established and discussed.