Radon concentrations in air, soil and water in a granitic areainstrumental development and measurements

Résumé

This Ph.D. Thesis deals with radon measurements in air, soil and water in a granitic area. On the same way, other determinations of natural radionuclides such as radium have been carried out. Concerning radon, a new system for radon exhalation measurements was developed. This new system is based on the use of silicon PIN photodiodes as radon detectors. The developed system does not use electrical field for exhalation measurements. A new method for the determination of radium content in water was applied for first time in Spanish drinking water samples. This method uses MnO2 coated discs for allowing the radium absorption. The discs are measured after exposition to water sample by alpha spectrometry. Finally radon indoor measurements were carried our using charcoal detectors and liquid scintillation spectrometer as detector. The main results indicate that 24 % of the places have a radon concentration greater than 400 Bqm-3, and 32% of them are above 200 Bqm-3, which are the recommended levels for radon indoors by European Union. After the measurement of radium, gross alpha and gross beta in 31 water samples taken from the study area, 39% of the samples have been found to be dangerous given that they exceed the legal Spanish limit of 0.1 Bq I-1 for gross alpha index. Radioactivity measurements have been done in environmental samples (air, water and soil) from a granitic area in situ and at LIBRA showing the importance and the potential risk of contamination by radium and radon for the population of some villages of this area.