STUDY OF THE OCCURRENCE OF RN-222 AND RA-226 IN DRINKING-WATER IN SPAIN

With the aim of determining the contribution of water to the backgroun d of natural radiation in Spain, the Rn-222 concentration levels were measured in domestic drinking water from a large part of the country, The water analyzed, both surface and groundwater, was collected in two areas of very distinct geological characteristics, pre-selected for t he likelihood of their containing high levels of 222Rn. This water was measured using a coaxial detector of high purity Ge, The overall resu lts demonstrate a log-normal distribution of Rn-222 levels, with a geo metric and arithmetic means of 10 and 381 Bq L(-1), respectively, and a range between detection limit of 2 Bq L(-1) and a maximum of 31,000 Bq L(-1). The Rn-222 concentrations measured in surface mater are gene rally below the detection limit, Significant differences have been fou nd depending on the geological characteristics of the area of referenc e, although the very distinct concentration levels of Rn-222 found in samples of similar lithology imply the influence of more complex facto rs in the solution of Rn-222 in water. Due to the relationship between radon and Ra-226, the concentration of the latter was measured in the same water using radiochemical separation and a scintillation ZnS(Ag) detector, No significant correlation between Ra-226 and Rn-222 concen trations has been observed unless measurements carried out in a high b ackground radiation region are considered separately.