A newly built radon calibration test bench called BACCARA is presented. A method of calibrationusing a secondary 222Rn standard is described and examples of calibration are given. With thismethod, no reference instrument is needed and one obtains a more accurate determination of the222Rn volume activity.
Radon progeny concentration is measured with a total alpha counting system in 185 dwellings in thetown of Thessaloniki. The Equilibrium Equivalent radon Concentration (EEC 222Rn) follows a lognormaldistribution with an arithmetic and geometric mean value of 28 Bq/m3 and 16 Bq/m3 respectively. Simultaneous in situ alpha and gamma spectroscopy measurements were performed in 60 schools of Thessaloniki. The mean equilibrium Equivalent Concentration of radon and thoron is 22 Bq/m3 and 0.9 Bq/m3 respectively.
Electret ion chamber (EIC) for monitoring radon consists of a stable electret (electrically chargedTeflon disc) mounted inside an electrically conducting chamber. PERM? passive integrating electretionization chambers for measuring radon in air has a restricted filtered passive access to radon (222Rn), allowing it to respond only to radon and not to thoron(220Rn) A modified unit called thoron monitor, with unrestricted access to thoron responds to both radon and thoron. Radon monitor and thoron monitor when used side by side allows measurement of both radon and thoron concentrations in air.
Indoor 222Rn concentrations are influenced by several factores which may change with time,thereby causing temporal fluctuations of radon concentrations in rooms.
The definition of radon prone area based on indoor radon survey and the statistical analysis of data (ICRP65) is a well known process. Such a definition of radon area involve all parameters that influence radon concentration in dwellings (geology, building technology, user habits, ventilation, etc.) and is useful especially for planing targeted Rn survey and remedial measures in existing houses. However, from the point of Rn protection of new modern buildings, the approach based on "Rnpotential" (geological parameters) seems to be more useful for delineation of radon area.
Accurate measurements of the radon flux of real building materials in existing houses with normalor contaminated walls and/or the mean emanation rate of soil samples, raw materials or building materials are very important for certain studies relating to radon in houses. The two potential sources of errors are that (1). The emanation rate of the disaggregated soil samples (raw materials, building materials), used in the emanation rate procedure outlined below, may be different from the emanation rate under natural setting conditions and (2).
Passive radon(222Rn) detectors are commonly used for radon surveys. They provide the integrated exposure. Solid-state nuclear track detectors (SSNTD) are widely used as the detecting material.Usually, determination of radon concentrations is based on the number of tracks produced by alpha particles (track density). In order to obtain the relationship between the track density and the radon concentration (conversion factor: CF) calibration is necessary. The detectors are calibrated in a pure radon atmosphere with a standard radon chamber.
A national survey of indoor radon levels in Lithuania was performed between 1995 and 1998. The main objective of this survey was to evaluate the average of indoor radon concentrations in Lithuania and to determine whether there were significant variations with different areas.
This study describes an approach for measuring and modeling diffusive and advective transport of radon through building materials. Goal of these measurements and model calculations is to improve our understanding concerning the factors influencing the transport of radon through building materials. To reach this goal, a number of experiments has to be conducted. These experiments, including measurements in a large cylinder for creating diffusive and advective transport of radon under controlled, dwelling-like conditions, are described here and the initial results are presented.
Various methods to determine ²²²Rn concentration in soil gas were tested at two sites with different soil types in a depth of 1 m. They include instantaneous (spot), continuous (real time) and timeaveraging procedures with advective ('active' procedures)
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