Les méthodes paléodosimétriques permettent d’obtenir l’âge de certains matériaux de nature minérale qui se comportent comme des dosimètres naturels, l’âge étant alors donné par le rapport de la dose accumulée depuis l’événement à dater, au débit de dose naturel auquel l'échantillon a été soumis. La détermination du débit de dose repose le plus souvent sur des modèles simples, qui seuls permettent des calculs explicites, mais ces modèles ne reproduisent que très imparfaitement la diversité des situations rencontrées. La modélisation informatique permet d’envisager des modèles plus complexes et plus réalistes, qui conduisent à simuler numériquement le débit de dose. Dans ce travail, la boite à outils Geant4, qui permet de simuler les interactions particule-matière selon la méthode de Monte-Carlo, a été utilisée pour créer des modèles complexes, ainsi que des outils de modélisation accessibles et adaptables aux différents types d'échantillons et situations dosimétriques. Des simulations ont tout d'abord été faites à partir de modèles basiques afin d'étudier l’origine des variations du débit de dose dans des sédiments, mettant en évidence les limites des modèles simples utilisés couramment. Ces informations ont permis d'orienter le développement d'outils de modélisation basés sur les codes de Geant4, et aussi de préciser les protocoles d'analyse des échantillons permettant de réunir les données nécessaires aux simulations numériques. Le programme DosiVox permet de modéliser simplement une grande variété d'échantillons grâce à une représentation voxélisée de l’objet et de son environnement, et de simuler la radioactivité pour calculer la distribution spatiale du débit de dose. Il a été développé dans une optique d'accessibilité et d'usage courant. Des comparaisons avec des situations dosimétriques préalablement étudiées, ou mesurées, ont montré la pertinence des modélisations, et les possibilités de cet outil informatique sont exposées au travers d’une série d'exemples et d'applications. La caractérisation de la distribution des débits de dose bêta dans les sédiments hétérogènes constitue l'une des problématiques les plus complexes à traiter. En plus d'une étude destinée à évaluer le potentiel de DosiVox à considérer ces situations, le programme DosiSed a été développé pour modéliser spécifiquement des ensembles polyminéraux de grains. Cet outil a permis d'étudier l'hétérogénéité du débit de dose dans des échantillons réels, ainsi que d'inclure certains résultats dans une problématique de datation. / The paleodosimetric dating methods allow to obtain the age of some mineral materials which behave as natural dosimeters, the age being derived as the ratio of the dose accumulated from the dated event and the natural dose rate to which the sample was subjected.. The determination of the dose rate is usually based on simple models which only allow explicit calculations, but these models reproduce very imperfectly the diversity of situations encountered. Computer modeling allows to represent more complex and more realistic models, which lead to numerically simulate the dose rate. In this work, the toolbox Geant4, allowing to simulate particle-matter interactions by the Monte-Carlo method, was used to create complex models , as well as modeling tools accessible and adaptable to different types of samples and dosimetric situations. Simulations were first made with basic models in order to study the origin of dose rate variations in sediments, highlighting the limits of the simple models commonly used. This information was used to guide the development of modeling tools based on the Geant4 codes, and also to specify the protocols of samples analysis for gathering the data needed for numerical simulations. The DosiVox software allows to easily model a wide variety of samples through a voxelised representation of the object and its environment, and to simulate the radioactivity for calculating the spatial distribution of the dose rate. It was developed with a view of accessibility and current use. Comparisons with dosimetric situations previously studied or measured showed the relevance of the modelings, and the possibilities of this computer tool are exposed through a series of examples and applications. The characterization of the beta dose rate distribution in heterogeneous sediment is one of the most complex problems to be treated. In addition to a study aims at assessing the potential of DosiVox to consider these situations, the DosiSed software was developed specifically for modeling poly-mineral sets of grains. This tool was used to study the heterogeneity of the dose rate in real samples and allowed to include some of the results in a dating problematic.

O Brasil possui a sétima maior reserva geológica de urânio do mundo, com aproximadamente 310 mil toneladas. A Província Uranífera de Lagoa Real, na região de Caetité e Lagoa Real, situado no centro sul da Bahia, é considerada a mais importante província monominerálica do Brasil. A população urbana que vive no distrito uranífero nas cidades de Caetité, Lagoa Real e Livramento de Nossa Senhora usa água potável oriunda do abastecimento público. Na área rural, caracterizada por freqüentes secas, os moradores recebem água de poços escavados e perfurados como também, de pequenas barragens e reservatórios abastecidos pelas chuvas. Este trabalho determinou os níveis de radioatividade alfa e beta total e as concentrações de urânio em diversos tipos de água consumidas pela população urbana e rural da Província Uranífera de Lagoa Real. As atividades α e β total foram determinadas com detector proporcional de fluxo gasoso e baixa radiação de fundo. As concentrações de urânio foram determinadas com o Espectrômetro de Massa com Fonte de Plasma Indutivo (ICP-MS). Os resultados obtidos foram comparados com as recomendações recentes de 2011 da Organização Mundial da Saúde, a portaria nº 2914 de 12/12/2011 do Ministério da Saúde e as resoluções do CONAMA. Os níveis de radiação natural variaram de 0,0041 ± 0,0004 Bq.L-1 a 0,80 ± 0,04 Bq.L-1 para a atividade alfa total e de 0,045 ± 0,003 a 3,0 ± 0,2 Bq.L-1 para a atividade beta total. Tendo como parâmetro a OMS e o MS, apenas duas amostras de água subterrânea, uma localizada na cidade de Lagoa Real e outra na cidade de Caetité apresentaram concentrações alfa total acima do valor de 0,5 Bq.L-1 descrito em suas recomendações, 0,80 ± 0,04 Bq.L-1 e 0,57 ± 0,03 Bq.L-1respectivamente. Para beta total, três amostras apresentaram níveis de radioatividade acima do limite de 1 Bq.L-1 recomendado pela Organização Mundial de Saúde e estabelecido pelo Ministério da Saúde; 3,0 ± 0,2 Bq.L-1; 1,63 ± 0,13 Bq.L-1 e 1,19 ± 0,07 Bq.L-1 todos situados no município de Lagoa Real. Duas amostras de água subterrânea no município de Caetité apresentaram concentrações de urânio acima do valor de 15 μg.L-1 determinado pelo CONAMA, 20,3 ± 0,3 μg.L-1 e 17,1± 0,3 μg.L-1. Em Lagoa Real, uma amostra apresentou níveis de urânio seis vezes superior ao limite estabelecido pelo Conselho Nacional de Meio Ambiente, 89,5 ± 1,5 μg.L-1. A Organização Mundial da Saúde em 2004 estabeleceu em suas recomendações o limite de 15 μg.L-1 como a concentração máxima de urânio na água potável. Em 2011 a OMS aumentou este limite para 30 μg.L-1. Levando-se em consideração as atuais recomendações da OMS, apenas a concentração de uma amostra de água apresentou níveis de urânio acima do recomendado, 89,5 ± 1,5 μg.L-1 no município de Lagoa Real. / Brazil has the seventh greatest geological uranium reserve in the world with approximately 310 thousand tons. The Lagoa Real Uranium Province, in the region of Caetité and Lagoa Real, situated in South Center Bahia, is considered the most important monomineralic province in Brazil. Urban population who lives in the uranium district in the cities of Caetité, Lagoa Real and Livramento de Nossa Senhora uses drinking water originated from public supply. In the rural area, characterized by frequent draughts, residents receive water from digged and drilled wells and from small dams and reservoirs, as well, which are supplied by the rains. This work determined the levels of total alpha and beta radioactivity and the uranium concentrations in several kinds of water consumed by urban and rural population from the Lagoa Real Uranium Province. Total α e β activities were determined with a low-level gas flow proportional detector. The uranium concentrations were determined with an inductive coupled plasma-mass spectrometer (ICP-MS). The results obtained were confronted with the latest World Health Organizations recommendations from 2011, the ordinance number 2914 of December 12 2011 from the Health Ministry and CONAMAs resolutions. Natural radiation levels varied from 0,0041 ± 0,0004 Bq.L-1 to 0,80 ± 0,04 Bq.L-1 for total alpha activity and from 0,045 ± 0,003 to 3,00 ± 0,2 Bq.L-1 for total beta activity. Having the WHO and the HM as parameter, just two underground water samples, one located in the city of Lagoa Real and the other in the city of Caetité presented total alpha concentration above the value of 0,5 Bq.L-1 described in its recommendations, 0,80 ± 0,040 Bq.L-1 and 0,57 ± 0,03 Bq.L-1 respectively. For total beta three samples presented radioactivity levels above the 1 Bq.L-1 limit recommended by the WHO and established by the Health Ministry; 3,00 ± 0,2 Bq.L-1; 1,63 ± 0,13 Bq.L-1 and 1,19 ± 0,07 Bq.L-1., all of them situated in the Lagoa Real town. Two samples of underground water from Caetité presented uranium concentrations above the value of 15 μg.L-1 determined by CONAMA, 20,3 ± 0,3 μg.L-1 and 17,1± 0,3 μg.L-1. In Lagoa Real one sample presented uranium levels six times over the limit established by the Environment National Council 89,5 ± 1,5 μg.L-1. In 2004 the World Health Organization established in its recommendations the 15 μg.L-1 limit as the maximum uranium concentration in drinking water. In 2011 the WHO increased that limit to 30 μg.L-1. Taking into account the current WHO recommendations only the concentration of one water sample presented uranium levels above the recommended, 89,5 ± 1,5 μg.L-1 in Lagoa Real.

O Brasil possui a sétima maior reserva geológica de urânio do mundo, com aproximadamente 310 mil toneladas. A Província Uranífera de Lagoa Real, na região de Caetité e Lagoa Real, situado no centro sul da Bahia, é considerada a mais importante província monominerálica do Brasil. A população urbana que vive no distrito uranífero nas cidades de Caetité, Lagoa Real e Livramento de Nossa Senhora usa água potável oriunda do abastecimento público. Na área rural, caracterizada por freqüentes secas, os moradores recebem água de poços escavados e perfurados como também, de pequenas barragens e reservatórios abastecidos pelas chuvas. Este trabalho determinou os níveis de radioatividade alfa e beta total e as concentrações de urânio em diversos tipos de água consumidas pela população urbana e rural da Província Uranífera de Lagoa Real. As atividades α e β total foram determinadas com detector proporcional de fluxo gasoso e baixa radiação de fundo. As concentrações de urânio foram determinadas com o Espectrômetro de Massa com Fonte de Plasma Indutivo (ICP-MS). Os resultados obtidos foram comparados com as recomendações recentes de 2011 da Organização Mundial da Saúde, a portaria nº 2914 de 12/12/2011 do Ministério da Saúde e as resoluções do CONAMA. Os níveis de radiação natural variaram de 0,0041 ± 0,0004 Bq.L-1 a 0,80 ± 0,04 Bq.L-1 para a atividade alfa total e de 0,045 ± 0,003 a 3,0 ± 0,2 Bq.L-1 para a atividade beta total. Tendo como parâmetro a OMS e o MS, apenas duas amostras de água subterrânea, uma localizada na cidade de Lagoa Real e outra na cidade de Caetité apresentaram concentrações alfa total acima do valor de 0,5 Bq.L-1 descrito em suas recomendações, 0,80 ± 0,04 Bq.L-1 e 0,57 ± 0,03 Bq.L-1respectivamente. Para beta total, três amostras apresentaram níveis de radioatividade acima do limite de 1 Bq.L-1 recomendado pela Organização Mundial de Saúde e estabelecido pelo Ministério da Saúde; 3,0 ± 0,2 Bq.L-1; 1,63 ± 0,13 Bq.L-1 e 1,19 ± 0,07 Bq.L-1 todos situados no município de Lagoa Real. Duas amostras de água subterrânea no município de Caetité apresentaram concentrações de urânio acima do valor de 15 μg.L-1 determinado pelo CONAMA, 20,3 ± 0,3 μg.L-1 e 17,1± 0,3 μg.L-1. Em Lagoa Real, uma amostra apresentou níveis de urânio seis vezes superior ao limite estabelecido pelo Conselho Nacional de Meio Ambiente, 89,5 ± 1,5 μg.L-1. A Organização Mundial da Saúde em 2004 estabeleceu em suas recomendações o limite de 15 μg.L-1 como a concentração máxima de urânio na água potável. Em 2011 a OMS aumentou este limite para 30 μg.L-1. Levando-se em consideração as atuais recomendações da OMS, apenas a concentração de uma amostra de água apresentou níveis de urânio acima do recomendado, 89,5 ± 1,5 μg.L-1 no município de Lagoa Real. / Brazil has the seventh greatest geological uranium reserve in the world with approximately 310 thousand tons. The Lagoa Real Uranium Province, in the region of Caetité and Lagoa Real, situated in South Center Bahia, is considered the most important monomineralic province in Brazil. Urban population who lives in the uranium district in the cities of Caetité, Lagoa Real and Livramento de Nossa Senhora uses drinking water originated from public supply. In the rural area, characterized by frequent draughts, residents receive water from digged and drilled wells and from small dams and reservoirs, as well, which are supplied by the rains. This work determined the levels of total alpha and beta radioactivity and the uranium concentrations in several kinds of water consumed by urban and rural population from the Lagoa Real Uranium Province. Total α e β activities were determined with a low-level gas flow proportional detector. The uranium concentrations were determined with an inductive coupled plasma-mass spectrometer (ICP-MS). The results obtained were confronted with the latest World Health Organizations recommendations from 2011, the ordinance number 2914 of December 12 2011 from the Health Ministry and CONAMAs resolutions. Natural radiation levels varied from 0,0041 ± 0,0004 Bq.L-1 to 0,80 ± 0,04 Bq.L-1 for total alpha activity and from 0,045 ± 0,003 to 3,00 ± 0,2 Bq.L-1 for total beta activity. Having the WHO and the HM as parameter, just two underground water samples, one located in the city of Lagoa Real and the other in the city of Caetité presented total alpha concentration above the value of 0,5 Bq.L-1 described in its recommendations, 0,80 ± 0,040 Bq.L-1 and 0,57 ± 0,03 Bq.L-1 respectively. For total beta three samples presented radioactivity levels above the 1 Bq.L-1 limit recommended by the WHO and established by the Health Ministry; 3,00 ± 0,2 Bq.L-1; 1,63 ± 0,13 Bq.L-1 and 1,19 ± 0,07 Bq.L-1., all of them situated in the Lagoa Real town. Two samples of underground water from Caetité presented uranium concentrations above the value of 15 μg.L-1 determined by CONAMA, 20,3 ± 0,3 μg.L-1 and 17,1± 0,3 μg.L-1. In Lagoa Real one sample presented uranium levels six times over the limit established by the Environment National Council 89,5 ± 1,5 μg.L-1. In 2004 the World Health Organization established in its recommendations the 15 μg.L-1 limit as the maximum uranium concentration in drinking water. In 2011 the WHO increased that limit to 30 μg.L-1. Taking into account the current WHO recommendations only the concentration of one water sample presented uranium levels above the recommended, 89,5 ± 1,5 μg.L-1 in Lagoa Real.

Η μεταπτυχιακή διατριβή με θέμα: «Φυσική Ραδιενέργεια των κλαστικών και ανθρακικών ιζημάτων στην περιοχή ανατολικά της Ηγουμενίτσας», έχει ως αντικείμενο την αναγνώριση, μελέτη και ανάλυση της φυσικής ραδιενέργειας των φυσικών ραδιονουκλιδίων U238, Th232, Ra226 και K40 στις κλαστικές αποθέσεις ηλικίας Μειοκαίνου (Ακουιτάνιο) και στις κλαστικές αποθέσεις των υποθαλάσσιων ριπιδίων Ηωκαίνου και Ολιγοκαίνου, και στο ποσοστό συγκέντρωσής τους στις παλαιότερες ανθρακικές και σύγχρονες κλαστικές ακολουθίες της περιοχής Νεράιδας Θεσπρωτίας, καθώς επίσης και στην ερμηνεία των αποτελεσμάτων ως προς την ταυτοποίηση της πηγής προέλευσής τους. Η περιοχή μελέτης ανήκει στη λεκάνη Φιλιάτες-Παραμυθιάς Ηπείρου και αποτελεί τμήμα ενός εκ των φλυσχικών συγκλίνων, τα οποία αναπτύσσονται στη δυτική Ελλάδα μέσα στην Ιόνια ζώνη, εξαιτίας της δράσης των εσωτερικών επωθήσεων. Η υπαίθρια δειγματοληψία πραγματοποιήθηκε στην ανθρακική και κλαστική ακολουθία, με τη συλλογή 45 συνολικά δειγμάτων, εκ των οποίων 8 ήταν ασβεστολιθικά, 18 ψαμμιτικά, 18 πηλιτικά και 1 σύγχρονης ποτάμιας άμμου. Η περιγραφή των ιζηματολογικών ενοτήτων βασίστηκε σε βιβλιογραφικά δεδομένα των γύρω περιοχών, καθότι δεν πραγματοποιήθηκαν ιζηματολογικές και γεωχημικές αναλύσεις. Οι κλαστικές ακολουθίες ταξινομήθηκαν βάσει του γεωλογικού χάρτη του Ι.Γ.Μ.Ε. φύλλο Φιλιάτες 1962-63, 1:50.000, ως αποθέσεις του Ανώτερου Φλύσχη ηλικίας Ακουιτανίου και αποθέσεις του Φλύσχη των Αγ. Πάντων ηλικίας Ηωκαίνου-Ολιγοκαίνου. Στην κατεύθυνση της ραδιοχημικής έρευνας, πραγματοποιήθηκε μια σειρά από ραδιοχημικές αναλύσεις σε όλο των αριθμό των δειγμάτων, προκειμένου να εκτιμηθεί η συγκέντρωση ενεργότητας των φυσικών ραδιονουκλιδίων των ανθρακικών και κλαστικών ακολουθιών, με σκοπό να εντοπιστεί η πηγή προέλευσής τους και η δυνατότητα αποθήκευσής τους, στους συγκεκριμένους σχηματισμούς. Η μέτρηση της συγκέντρωσης ενεργότητας του 238U, 226Ra, 232Th, και 40K έγινε με τη μέθοδο της γ-φασματομετρίας, με τη χρήση υπερκάθαρου ανιχνευτή γερμανίου (HPGe) της Canberra. Ο κύριος στόχος αυτής της προσπάθειας, ήταν να διαπιστωθεί η ύπαρξη των φυσικών ραδιονουκλιδίων στην ανθρακική ακολουθία, καθώς και η συγκέντρωσή τους στην κλαστική ακολουθία, λόγω δευτερογενούς μετανάστευσής τους, από τις ήδη ταυτοποιημένες φωσφορούχες αποθέσεις των γειτονικών περιοχών. Η περιοχή μελέτης δεν εμφάνισε υπερβολικές τιμές συγκέντρωσης ενεργότητας φυσικών ραδιονουκλιδίων σε κανέναν από τους γεωλογικούς σχηματισμούς που ερευνήθηκαν. Η ανθρακική ακολουθία της περιοχής χαρακτηρίστηκε πολύ φτωχή στα υπό μελέτη φυσικά ραδιονουκλίδια, σε αντίθεση με την κλαστική ακολουθία, η οποία εμφάνισε γενικά αυξημένες τιμές συγκέντρωσης ενεργότητας φυσικών ραδιονουκλιδίων. Τέλος, βάσει των συγκεντρώσεων που εντοπίστηκαν στις σύγχρονες ποτάμιες προσχώσεις της περιοχής μελέτης, τα Τεταρτογενή ιζήματα της περιοχής χαρακτηρίστηκαν ως αρκετά εμπλουτισμένα, συμπεραίνοντας την ύπαρξη σύγχρονης τροφοδοσίας φυσικών ραδιονουκλιδίων μέσω οριζόντιων ρηγμάτων. Συμπεραίνοντας, οι κλαστικές ακολουθίες του Φλύσχη των Αγ. Πάντων, Ηωκαίνου και Ολιγοκαίνου και τα Τεταρτογενή ιζήματα της περιοχής, δεν χαρακτηρίζονται ως άμεσα προτεινόμενοι σχηματισμοί για τη χρήση αδρανών υλικών, ενώ προτείνεται εκτενέστερη μελέτη στους Τεταρτογενείς σχηματισμούς της Εξωτερικής Ιονίου. / The subject of postgraduate thesis «Natural radioactivity of clastic and carbonate sediments located eastern of Igoumenitsas area (Western Greece)» is dealing with the recognition, study and analysis of natural radioactivity of natural radionuclides U238, Th232, Ra226 και K40 in the Miocene (Aquitanian) clastic deposits, Eocene and Oligocene clastic deposits of the submarine fans and their concentration amount in the older carbonate and contemporary clastic sequences of the study area located in the village Neraida of Thesprotia. It also deals with the interpretation of results in terms of the identification of the source. The study area is located in the basin of Filiates-Paramithia of Epirus and constitutes a part of the flysch syclins, developed in Western Greece within the Ionian zone, due to the activity of internal thrusts. The sampling was accomplished in the carbonate and clastic sequences, with the collection of 45 rock samples: 8 limestones, 18 sandstones, 18 siltstones and 1 sample of contemporary fluvial sand. The sedimentological units description was based in bibliographical data, since sedimentological and geochemical analyses were not accomplished. The clastic sequences were classified based on the geological map of I.G.M.E. Filiates sheet 1962-63, 1:50.000, as Upper Flysch depotites Aquitanian ages and Ag. Panton Flysch deposites Eocene-Oligicene ages. Towards the radiochemical research a sequence of radiochemical analyzes were accomplished, in order to evaluate the activity concentration of natural radionuclides of carbonate and clastic sequences, with the aim of locating their source and the potential of their storage in these specific formations. The activity concentration measurement of 238U, 226Ra, 232Th, and 40K was carried out with gamma-spectometry method, using the High Purity Germanium detector (HPGe) of Canberra Company. The main aim of this effort was the establishment of the existence of the natural radionuclides in the carbonate sequence, as well as their concentration in the clastic sequence, due to their secondary migration from the already identified phosphatic deposits of the adjacent areas. None of the studied geological formations of the study area presented exaggerating activity concentration of natural radionuclides values. The carbonate sequence in terms of the studied natural radionuclides was characterized as quite poor, contrasting to the clastic sequence, which generally showed increasing activity concentration of natural radionuclides values. Finally, based on the concentrations traced in the contemporary fluvial deposits of the study area, the Quaternary sediments of the area were characterized as sufficiently enriched, concluding to the existence of contemporary source of natural radionuclides through horizontal faults. Concluding, the Eocene – Oligocene clastic sequences of Ag. Panton Flysch and the Quaternary sediments of the area, are not characterized as immediately preferred formations for the usage of aggregate materials, while additionally a more extensive research in the Quaternary formations of External Ionian Zone is suggested.

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Made available in DSpace on 2014-10-09T12:43:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:03Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) - IPEN Apendices / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T13:47:28Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T13:47:28Z (GMT). No. of bitstreams: 0 / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Measurements of radioactivity in the environment are of great importance in monitoring and control of radiation levels to which humans are exposed directly or indirectly. Two nuclear power plants are planned in the northeast Brazilian region by the Ministry of Mines and Energy under the National Energy Plan 2030. Even without defining the exact location were these new plants would be built; there is great speculation that new units will soon be built along the banks of the San Francisco River. This region is extremely poor in studies from the standpoint of determining the type of radionuclide and radioactivity in the environment, being practically non-existent in the literature data on the state of Sergipe. This study aimed to contribute to analysis of the occurrence of natural and artificial radioactive material in soil, water and food products of the State of Sergipe, focusing primarily on Neópolis Plateau region, which is located the banks of the Rio San Francisco. For this purpose, radionuclides found in all samples collected from soil and cement, fertilizer and food chain products were analyzed by gamma spectrometry, whose activity was measured employing a HPGe detector. The highest activity was determined due to K-40 (1636 + 35) ´ 10 Bq.kg-1 in KCl fertilizer, and the lowest activity was due to Bi-212 (0.001 + 0.009) Bq.kg-1 in lemon peel. The activities of radionuclides measured in all samples are below the Brazilian criteria for exclusion, exemption and waiver required for protection against radiation. Be-7 was detected in organic fertilizers and lemon peel and Th-232 found in samples of soil and cement in the state of Sergipe, both unprecedented results in the literature. It was also detected Cs-137 in some samples, probably from fertilizers and food additives imported from northern countries, yet their activities do not pose a risk to the population. / Medições de radioatividade no ambiente têm grande importância na monitoração e controle de níveis de radiação a que o homem está exposto, direta ou indiretamente. Duas centrais nucleares são previstas no nordeste pelo Ministério de Minas e Energia segundo o Plano Nacional de Energia 2030. Mesmo sem a definição do local exato onde serão construídas essas novas centrais, há grande especulação que novas unidades serão em breve construídas ao longo das margens do rio São Francisco. Esta região é extremamente pobre em estudos do ponto de vista da determinação do tipo de radionuclídeos e da radioatividade presentes no meio ambiente, sendo praticamente inexistente na literatura dados sobre o Estado de Sergipe. Este trabalho teve por objetivo contribuir com análises da ocorrência de material radioativo natural e artificial no solo, água e produtos alimentícios do Estado de Sergipe, focando a região do Platô de Neópolis, grande produtora de alimentos nesse Estado, e que se localiza as margens do Rio São Francisco. Para este fim, todos os radionuclídeos encontrados nas amostras coletadas de solo e cimento, fertilizantes e produtos da cadeia alimentar foram analisados por espectrometria gama, cuja atividade de foi medida empregando-se um detector HPGe. A maior atividade determinada foi devido ao K-40 (1636 + 35) ´ 10 Bq.kg-1 no fertilizante KCl; e a menor atividade foi devido ao Bi-212 (0,001 + 0,009) Bq.kg-1 na casca de limão. As atividades de radionuclídeos medidos em todas as amostras estão abaixo do limite de brasileiros dos critérios de exclusão, isenção e dispensa exigidos para proteção contra as radiações. Foi detectado Be-7 em adubos orgânicos e casca de limão e Th-232 encontrado em amostras de solo e cimento no estado de Sergipe, ambos os resultados sem precedentes na literatura. Foi também detectado Cs-137 em algumas amostras, provavelmente proveniente de fertilizantes e complementos alimentares importados de países do hemisfério norte; no entanto suas atividades não representam risco para a população.

Made available in DSpace on 2014-10-09T12:43:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:39Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) - IPEN / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:43:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:03Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) - IPEN Apendices / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP