Adecuación y desarrollo de métodos de análisis de datos obtenidos mediante espectrometría gamma para la medida de la radiactividad ambiental en tiempo real

Identificador:  TDX:2746

Handle: https://hdl.handle.net/20.500.11797/TDX2746

Autors:  Prieto Butillé, Elena

Resum:
The Environmental Radiological Surveillance Network implemented in Catalonia consists of several types of detectors for real time automatic measurement of the environmental radiation. Among these are the gamma spectrometry monitors using NaI (Tl) and LaBr3 (Ce) scintillation detectors. Environmental measurements measured with real-time gamma-ray spectrometry monitors are not significant until they are adequately processed. These processes include spectrum stabilisation, energy, resolution and efficiency calibrations and subtraction of the detector's intrinsic background. This study presents the process of spectra adequacy for a water monitor with LaBr3(Ce) detector. Stabilised and calibrated spectra can be subjected to data analysis processes. Form spectra, the ambient dose equivalent H*(10) or the activity concentration of isotopes can be obtained. The ambient dose equivalent H*(10) is the quantity used in legislation related to limits on dose to public exposure. We present a method for the calculation of H*(10) obtained from environmental gamma spectra based on Monte Carlo simulations with the EGS5 code. The values obtained from the spectrometric data registered by a monitor with a LaBr3(Ce) detector are compared with those provided by a Geiger Muller counter calibrated in H*(10). Finally, a spectral regions analysis method of gamma spectra is presented for the automatic and real-time monitoring of the activity concentrations of natural and artificial isotopes. The method solves peak overlapping and eliminates the additional contribution caused by the presence of natural radiation within each region. Results of laboratory measurements for artificial (Cs-137 and I-131) and natural (Bi-124 and Pb-214) isotopes are presented.