Le Réacteur Jules Horowitz (RJH) est un réacteur d’irradiation technologique actuellement en construction au CEA Cadarache. Ce réacteur permettra de réaliser les études scientifiques sur le comportement des matériaux et des combustibles sous irradiation.Pour répondre aux enjeux du RJH, il est nécessaire de valider les outils de calcul des échauffements photoniques (les codes de calcul et la librairie européenne JEFF3.1.1 de données nucléaires) pour le cas spécifique du RJH. Cette problématique est traitée en 3 volets dans cette thèse.Le 1er volet a consisté à quantifier le biais de calcul dû aux données nucléaires de la librairie européenne JEFF3.1.1 pour les calculs d’échauffements photoniques dans le RJH. Ce travail repose sur l’interprétation, avec le code TRIPOLI-4, de mesures d’échauffements réalisées dans la maquette critique EOLE du CEA Cadarache.Le 2ème volet a consisté à obtenir des éléments sur les biais de calcul des échauffements photoniques dus aux méthodes de calcul elles-mêmes. La comparaison calcul / calcul entre différents codes Monte Carlo met en évidence l’importance du transport des particules chargées pour les calculs d’échauffements.Le 3ème volet de ce travail a consisté à fournir des points de comparaison calcul / mesure pour des mesures d’échauffements réalisées dans le réacteur OSIRIS avec une première version du dispositif CARMEN. Le dispositif CARMEN est un projet de dispositif de mesure multi-détecteur innovant pour le RJH. En conclusion, cette thèse a apporté des éléments de validation des calculs d’échauffements photoniques pour le RJH. Ces éléments ont d’ores et déjà été capitalisés pour les études de sûreté du RJH. / The Jules Horowitz Reactor (JHR) is the next MTR under construction at CEA Cadarache research center. The JHR will be a major research infrastructure for the test of structural material and fuel behavior under irradiation.To be up to the challenges set by the JHR, It is necessary to validate photon-heating calculation tools (calculation codes and the European nuclear-data JEFF3.1.1 library) for specific use in the JHR. This topic is handled with a three-prong work plan. The first part consisted in quantifying the calculation bias due to the JEFF3.1.1 nuclear-data library on JHR photon-heating calculations. This work relies on the interpretation, with the TRIPOLI-4 code, of heating measurements carried out in the EOLE critical mock-up at CEA Cadarache.The second part of this work is dedicated to the determination of photon-heating calculation biases linked to the approximations of calculation schemes. The calculation / calculation comparison between different Monte Carlo codes highlights the importance of charged-particle transport for heating calculations.The third part of this work consisted in providing calculation / measurement comparisons for heating measurements carried out in the OSIRIS reactor with a prototype of the CARMEN device. The CARMEN device aims at measuring neutron flux, photon flux and nuclear heating simultaneously in the different experimental locations of JHR. In conclusion, this work brings forth validation elements for JHR photon-heating calculations. These elements are already taken into account for the estimation of biases and uncertainties associated with photon-heating calculations for JHR performance and safety studies.

A fim de implementar o novo código de prática da Agência Internacional de Energia Atômica (AIEA) no Brasil, o Laboratório de Calibração de Instrumentos (LCI/IPEN) está realizando calibrações em termos de kerma no ar e em termos de dose absorvida na água, em feixes de 60Co. As razões ND,w/NK obtidas são comparadas com valores da literatura, obtendo-se concordância satisfatória. As diferenças entre os valores das razões CK (ND,w/NK) obtidas no presente trabalho e os valores da literatura são devidas a vários fatores. Estes fatores podem ser as variações entre as câmaras, que devem ser objeto de diferenças nas incertezas estimadas pelos PSDLs, e as diferenças nos padrões utilizados por cada Instituto de Metrologia Nacional (NMI) ou Laboratório de Dosimetria. No entanto, se forem conhecidas as razões entre cada NMI e o BIPM, para os padrões de kerma no ar e de dose absorvida na água, é possível a normalização das razões CK medidas para as razões equivalentes ao BIPM. Todos os resultados de razões CK obtidos foram convertidos para as razões equivalentes ao BIPM para facilitar a comparação. Neste trabalho é discutida a utilização da razão CK como parâmetro de controle de qualidade na verificação de resultados das calibrações rotineiras. Para avaliação dos procedimentos de calibração adotados no LCI, foram realizados testes de estabilidade a longo prazo com as câmaras de ionização padrões. Além disso, foi criado um banco de dados para armazenamento dos dados de calibração, com o objetivo de melhorar a qualidade do procedimento de calibração. / In order to implement the new IAEA code of practice in Brazil the national calibration laboratories, the Laboratory of Instrument Calibration (LCI/IPEN) is calibrating clinical dosimeters in terms of both air kerma and absorbed dose to water in a 60Co gamma ray beam. The ND,w/NK ratios thus obtained are then compared with the literature values; a satisfactory agreement has been found. The differences between the CK values obtained in the present work and the literature values may be due to several components. These could be the chamber-to-chamber variations which may be subject to different estimated uncertainties by PSDLs, and the variations in the standards used by each National Metrology Institute (NMI) or Dosimetry Laboratory. However, since the ratio of both air kerma and absorbed dose to water standards for each NMI to those of the BIPM are known, it is possible to reduce the measured ratios to the expected BIPM equivalent ratios. All these CK results have been converted to the BIPM equivalent values to facilitate comparison. The use of the CK value as a and quality control parameter to verify the results of the routine calibrations is discussed in this work. The long term stability of wich standard ionization chamber was checked in order to evaluate the calibration procedures followed at LCI. Moreover, a database was created to store the calibration data aiming the quality improvement of the calibration procedure.

A fim de implementar o novo código de prática da Agência Internacional de Energia Atômica (AIEA) no Brasil, o Laboratório de Calibração de Instrumentos (LCI/IPEN) está realizando calibrações em termos de kerma no ar e em termos de dose absorvida na água, em feixes de 60Co. As razões ND,w/NK obtidas são comparadas com valores da literatura, obtendo-se concordância satisfatória. As diferenças entre os valores das razões CK (ND,w/NK) obtidas no presente trabalho e os valores da literatura são devidas a vários fatores. Estes fatores podem ser as variações entre as câmaras, que devem ser objeto de diferenças nas incertezas estimadas pelos PSDLs, e as diferenças nos padrões utilizados por cada Instituto de Metrologia Nacional (NMI) ou Laboratório de Dosimetria. No entanto, se forem conhecidas as razões entre cada NMI e o BIPM, para os padrões de kerma no ar e de dose absorvida na água, é possível a normalização das razões CK medidas para as razões equivalentes ao BIPM. Todos os resultados de razões CK obtidos foram convertidos para as razões equivalentes ao BIPM para facilitar a comparação. Neste trabalho é discutida a utilização da razão CK como parâmetro de controle de qualidade na verificação de resultados das calibrações rotineiras. Para avaliação dos procedimentos de calibração adotados no LCI, foram realizados testes de estabilidade a longo prazo com as câmaras de ionização padrões. Além disso, foi criado um banco de dados para armazenamento dos dados de calibração, com o objetivo de melhorar a qualidade do procedimento de calibração. / In order to implement the new IAEA code of practice in Brazil the national calibration laboratories, the Laboratory of Instrument Calibration (LCI/IPEN) is calibrating clinical dosimeters in terms of both air kerma and absorbed dose to water in a 60Co gamma ray beam. The ND,w/NK ratios thus obtained are then compared with the literature values; a satisfactory agreement has been found. The differences between the CK values obtained in the present work and the literature values may be due to several components. These could be the chamber-to-chamber variations which may be subject to different estimated uncertainties by PSDLs, and the variations in the standards used by each National Metrology Institute (NMI) or Dosimetry Laboratory. However, since the ratio of both air kerma and absorbed dose to water standards for each NMI to those of the BIPM are known, it is possible to reduce the measured ratios to the expected BIPM equivalent ratios. All these CK results have been converted to the BIPM equivalent values to facilitate comparison. The use of the CK value as a and quality control parameter to verify the results of the routine calibrations is discussed in this work. The long term stability of wich standard ionization chamber was checked in order to evaluate the calibration procedures followed at LCI. Moreover, a database was created to store the calibration data aiming the quality improvement of the calibration procedure.

<p>A facility for studies of elastic neutron scattering in the 50–130 MeV range has been developed. In addition to elastic neutron scattering, it has been used for (n,p) and (n,d) reaction experiments. The performance of the device has been illustrated in measurements of the (n,p) and (n,n) cross sections on ¹H and ¹²C.</p><p>Elastic neutron scattering from ¹²C and ²⁰⁸Pb has been studied at 96 MeV in the 10–70 degree interval. The achieved energy resolution, 3.7 MeV, is about one order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3 %, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target.</p><p>The results are compared with modern optical model predictions, based on phenomenology or microscopic nuclear theory. The data on ²⁰⁸Pb are in general in good agreement with the theory models.</p><p>All theory models fail to describe the ¹²C data in the 30–50 degree interval, where the models predict a saddle structure not displayed by the present experimental data. Various reasons for this discrepancy have been investigated. For the other parts of the angular range studied, the agreement is good.</p><p>These measurements have to a large degree been motivated by needs in various application areas, i.e., nuclear waste incineration by fast neutrons and biomedical effects caused by neutrons. The implications of the present results on these applications are discussed.</p>

A facility for studies of elastic neutron scattering in the 50–130 MeV range has been developed. In addition to elastic neutron scattering, it has been used for (n,p) and (n,d) reaction experiments. The performance of the device has been illustrated in measurements of the (n,p) and (n,n) cross sections on 1H and 12C. Elastic neutron scattering from 12C and 208Pb has been studied at 96 MeV in the 10–70 degree interval. The achieved energy resolution, 3.7 MeV, is about one order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3 %, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic nuclear theory. The data on 208Pb are in general in good agreement with the theory models. All theory models fail to describe the 12C data in the 30–50 degree interval, where the models predict a saddle structure not displayed by the present experimental data. Various reasons for this discrepancy have been investigated. For the other parts of the angular range studied, the agreement is good. These measurements have to a large degree been motivated by needs in various application areas, i.e., nuclear waste incineration by fast neutrons and biomedical effects caused by neutrons. The implications of the present results on these applications are discussed.

The Coarse-Mesh Transport Method (COMET) is a method developed by the Computational Reactor and Medical Physics Group at Georgia Tech. Its original application was neutron transport for nuclear reactor modeling. COMET has since been shown to be effective for coupled photon-electron transport calculations where the goal is to determine the energy deposition of a photon beam. So far COMET can simulate a mono-directional, mono-energetic, spatially-flat photon beam. The goal of this thesis will be to extend COMET by adding a generalized source treatment. The new source will be able to simulate beams that vary in intensity as a function of position, angle, and energy. EGSnrc will be used to verify the accuracy of the new method for 3D photon kerma calculations.

Made available in DSpace on 2014-10-09T12:52:11Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:13Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Made available in DSpace on 2014-10-09T12:52:11Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:13Z (GMT). No. of bitstreams: 0 / Neste trabalho foram avaliados aventais de proteção e blindagens de ovário de cinco fabricantes segundo as normas NBR / IEC 61331-1 e NBR / IEC 61331-3 de 2004. Para a determinação da espessura equivalente de atenuação foram aplicadas três metodologias diferentes (interpolação linear, modelo de Archer e somatório de exponenciais), uma vez que a norma não indica como este valor deve ser obtido. Além disso, foram estimadas as incertezas associadas a cada método e a influência do número de medições na incerteza combinada. As características de confecção avaliadas foram: documento acompanhante, projeto, materiais, dimensões e marcação da etiqueta. Para esta avaliação foi elaborado um formulário que contemplava todas as exigências da NBR / IEC 61331-3. Os resultados mostraram uma grande diferença entre os valores de espessura equivalente de atenuação declarados e medidos. A comparação dos resultados das três metodologias aplicadas mostrou que há pouca variação entre os valores obtidos e entre as incertezas associadas nas diferentes metodologias. Foi possível observar também que o número de medições não contribui significativamente para o aumento da incerteza nas três metodologias. A metodologia que melhor se adequou à rotina do laboratório foi a metodologia da interpolação linear com cinco medições da taxa de kerma no ar. A discrepância entre os resultados apresentados neste trabalho e as exigências das normas estudadas mostra a necessidade de tornar compulsória a certificação dos dispositivos de proteção, contribuindo assim para o aumento da proteção radiológica do usuário. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:43:37Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:51Z (GMT). No. of bitstreams: 1 06644.pdf: 6476949 bytes, checksum: 537fe5234ba74d48639417cebfe94231 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP