A new passive radon-thoron discriminative measurement system.

A new passive radon-thoron discriminative measurement system has been developed for monitoring radon and thoron individually. It consists of a 'couple' of passive integrating devices with a CR39 nuclear track detector (NTD). The experimental prototype is based on the application of a new concept of NTD instrument developed at ENEA, named Alpha-PREM, acronym of piston radon exposure meter, which allows controlling the detector exposure with a patented sampling technique (Int. Eu. Pat. and US Pat.). The 'twin diffusion chambers system' was based on two A-PREM devices consisting of the standard device, named NTD-Rn, and a modified version, named NTD-Rn/Tn, which was set up to improve thoron sampling efficiency of the diffusion chamber, without changing the geometry and the start/stop function of the NTD-Rn device. Coupling devices fitted on each device allowed getting a system, which works as a double-chamber structure when deployed at the monitoring position. In this paper both technical and physical aspects are considered.

ENEA Reference Atmosphere Facility for Testing Radon and Daughters Measuring Equipment.

This paper gives the technical characteristics of the Italian Committee for Research and Development of Nuclear Energy and Alternative Energy (ENEA) radon chamber and the operational procedures developed for testing radon and daughters measuring equipment. Runs were carried out under different experimental conditions defined in terms of radon and daughter concentrations, equilibrium ratio (F-factor), and aerosol concentration and size distribution. Stable radon reference atmospheres with known equilibrium factors were obtained using standard aerosols.

The Italian national survey of indoor radon exposure.

An investigation is being developed by the Comitato Nazionale per la Ricerca e per lo Sviluppo dell'Energia Nucleare e delle Energie Alternative, ENEA, to assess the indoor exposure of the Italian population. The programme, which started in 1982, includes regional and local surveys in all the administrative districts and intensive investigations of factors which influence indoor radon levels. The survey is organized by statistical areas of sampling to obtain representative samples of houses. The definition of the areas takes into account basic parameters e.g. geolithological environments, radon soil gas from underlying soils and rocks, specific activities of local building materials, climatic and seasonal variations, building technology, types of houses and town planning. The collected data may also be used for the compilation of radon risk maps to plan special monitoring and remedial actions if needed. Preliminary results concerning the above items are discussed.

Results of a survey on radioactivity of building materials in Italy.

A program is underway in Italy to identify construction materials with high radioactivity contents and to evaluate the resulting indoor exposure on a nationwide scale. Building materials surveyed include those of natural origin and those employing particular by-products such as fly ash and phosphogypsum. The survey currently emphasizes natural building materials, which are widely used in many areas having particular geological features. First results show that Italy includes areas of high natural background, i.e. in Lazio and Campania, in which very high levels of indoor exposure occur that can be directly related to specific activities of the building materials. Moreover, 220Rn daughters are sometimes present at such levels that their contribution to the lung exposure is comparable to that from 222Rn daughters.