Estonian waterworks treatment plants: clearance of residues, discharge of effluents and efficiency of removal of radium from drinking water.

Considerable levels of radium were detected in a certain fraction of the Estonian drinking water supply network. Some of these waterworks have treatment systems for the removal of (mainly) iron and manganese from drinking water. Three of these waterworks and another one equipped with a radium removal pilot plant were examined, and a specific study was conducted in order to assess the environmental compatibility of effluents and residues produced in the plants. (226)Ra and (228)Ra activity concentrations were analysed in both liquid (backwash water) and solid (sand filter and sediment) materials to evaluate their compliance, from the radiological point of view, with current Estonian legislation and international technical documents that propose reference levels for radium in effluents and residues. Also with regard to water treatment by-products, a preliminary analysis was done of possible consequences of the transposition of the European Basic Safety Standards Draft into Estonian law. Radium removal efficiency was also tested in the same plants. Iron and manganese treatment plants turned out to be scarcely effective, whilst the radium mitigation pilot plant showed a promising performance.

Radium isotopes in Estonian groundwater: measurements, analytical correlations, population dose and a proposal for a monitoring strategy.

In some areas of Estonia, groundwater contains a significant number of natural radionuclides, especially radium isotopes, which may cause radiation protection concern depending on the geological structure of the aquifer. Indeed, the parametric value of 0.1 mSv y⁻¹ for the total indicative dose established by European Directive 98/83/EC, adopted as a limit value in Estonian national legislation, is often exceeded. A Twinning Project between Estonia and Italy was carried out within the framework of the Estonian Transition Facility Programme, sponsored by the European Union. Its aims were to assess the radiological situation of Estonian groundwater and related health consequences. The first step was a study of Estonian aqueducts and the population served by them, and a thorough analysis of the radiological database for drinking water, from which the relevant effective doses for the population were obtained. Particular attention was devoted to doses to children and infants. Correlations between the chemical parameters were investigated, in order to suggest the best possible analytical approach. Lastly, a monitoring strategy, i.e. sampling points and sampling frequencies, was proposed.

Impact to public and environment of NORM industries in Italy.

Italian legislation requires companies undertaking certain work activities involving naturally occurring radioactive materials (NORM) to check compliance with action levels (1 mSv y(-1) for workers, 0.3 mSv y(-1) for the public). A project is being carried out by ARPAV and other Environmental Agencies to estimate doses to members of the public from NORM from several activities (refractory and tile industry, integrated steelworks, phosphate industry, aluminium production, coal-fired power plants). Activity concentration values of residues have been compared with general clearance levels given in Radiation Protection 122 part 2 and, in several cases, these levels appeared to be exceeded. Doses due to air emissions from stacks, from wastes in disposal sites and from the use of fertilisers in agriculture have been calculated through simulation models (PC-Cream, Resrad, Unscear algorithms), which produce fairly low dose estimates. A major problem for NORM control in Italy at the moment is the lack of official technical and legislative rules (concerning, for instance, residues and effluents management).

Management of NORM-containing processing residuals from hydrocarbons extraction and treatment plants.

Eni, in collaboration with ARPA Veneto, laid down a procedure for the exposure assessment of workers and the public to natural radionuclides contained in oil sludge during their future removal from hydrocarbons extraction and treatment plants. Reference legislation for this study is Italian Legislative Decree 241/00, which regulates protection from exposure to ionising radiation also for working activities with naturally occurring radioactive materials.

Radon mapping in south Tyrol: comparison between two different procedures.

In this paper two different procedures for radon mapping have been compared on the same database referring to indoor radon records of South Tyrol. The first procedure is based on descriptive statistics applied to administrative units while the second one implies a more complicated statistical analysis applied to a regular grid: it involves floor level normalization of radon data, filling and smoothing algorithms for the territory cells.

Retrospective assessment of historic radon concentrations in Norwegian dwellings by measuring glass implanted Po-210--an international field intercomparison.

The first Norwegian study of historic radon concentrations in 17 dwellings in the high radon areas in Norway has been conducted as part of an international field intercomparison during 1998. The retrospective radon concentration is estimated via measurements of Po-210, the long-lived decay product of Rn-222 implanted in glass surfaces of objects like pictures, mirrors, cabinet-glass, etc. the method called 'surface trap'. Three different surface trap techniques to assess the implanted Po-210 activity and two different procedures to estimate retro radon from Po-210 data were used. The Po-210 and the retrospectively estimated radon results agree reasonably well over a wide range of concentrations. Historic radon concentrations were also estimated from analysis of a smaller number of 'volume trap' samples (pieces of spongy materials), and the results compared to those from 'surface traps'. The retro radon results correlate with contemporary radon results with a correlation coefficient of 0.877. To evaluate uncertainty in Po-210 measurements due to varying position on the glass a study of spatial homogeneity of three sample glasses was conducted and variations between 12% and 18% were found.

Integrated natural radiation exposure studies in stable Yugoslav rural communities.

The results of field investigations of natural radiation exposures of the general population in two stable rural communities in Yugoslavia are presented. The principal emphasis was on exposures to contemporary indoor radon, but measurements of external penetrating radiation absorbed dose rates in air were carried out in the majority of cases. In addition, in a limited number of dwellings, measurements of thoron gas concentrations were made. By means of making a series of sequential 3-month radon measurements, both seasonal variations and annual average radon levels in the dwellings were determined. Using passive alpha track detectors, individual radon and thoron indoor concentrations as high as 9591 Bq m(-3) and 709 Bq m(-3), respectively, were detected while absorbed dose rates in air in the dwellings as high as 430 nGy h(-1) were recorded. On the basis of these different types of measurements, assessments could be made of the integrated natural radiation exposures being received by the populations. In addition to contemporary radon measurements, retrospective radon exposure assessments in most of the dwellings were made on the basis of measurements of 210Po concentrations in both surface (glass) traps and in volume (porous materials) traps. A description is given of the sampling strategies and protocols used in this field work. It is shown that at least one stable rural community receiving high natural radiation exposures, has been clearly identified and plans for future health investigations of the population there are outlined.

In progress identification of radon prone areas: Toscana and Veneto.

Two studies aimed at defining radon prone areas in Toscana and Veneto, based on indoor measurements, are merged in this paper to extract the key points for a possible general methodology. In territorial units, the geometric mean (GM) and standard deviation (GSD) are evaluated from empirical data and the fraction of dwellings above the reference level (RL) is derived according to a log-normal model. In Toscana the sampling base is made of nearly 1,000 measurements (dwellings and kindergartens), apportioned according to the lithological classes (22) of the region. In Veneto 1,230 measurements in dwellings of the upper part of the region (estimates are given for the south), have been assigned to 6 x 5 km2 sequential units of the territory: the detection floor has been considered and results are referred to the regional mean dwellings condition with respect to the floor. Empirical GM and GSD values are corrected to increase statistical power based on two different methods. Maps of the percentages of dwellings with more than 200 Bq x m(-3) are presented. Areas with magmatic rocks in southern Toscana and northern parts of Vicenza and Belluno provinces in Veneto clearly emerge with more than 10% of dwellings above 200 Bq x m(-3). Efforts are required to establish proper confidence limits for estimates and to trace radon maps upon an administrative basis.