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1
Kadiri, Lawal Abdul. "Dosimetry for absolute biological effectiveness of ionising radiations." Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/13336.
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It was shown that the conventional radiation dosimetric system which is based on RBE and LET is incapable of determining the likely consequences of ionising radiation exposure. Analyses of data on the induction of the chromosome aberrations, mutations and transformation in mammalian cells by radiations of different types and energies has indicated that (a) the induction of double strand breaks (dsb) in the DNA is their common critical lesion, (b) Fast ions and neutrons radiations are by order of magnitude more damaging than photons and electrons of equal mean free path, (c) Damage is through intra track action of the charged particles. A new system of radiation dosimetry, which does not require a radiation quality parameter, was proposed. It was based on the observation that for each of the biological endpoints considered an Absolute Biological Effectiveness (ABE) for damage by the charged particles can be defined as the product of the charged particle fluence and the saturation effect cross section, scaled with the efficiency (e) of damage by radiation of mean free path (lambda). e is given by 1-exp-(lambda0/lambda), where lambda0), about 1.8nm, is the mean inter-strand distance of the DNA. The physical requirements for its instrumentation, basically the emulation and quantification of the induction of dsb in the DNA, were defined. The feasibility for its realisation using detectors based on gas ionisation, superconductivity, secondary electron emission, and semiconductivity was assessed. Ultrathin films of rectified, organic semiconductors appeared to have the best potential, but such materials are not yet available in the physically characterised form as may be required for detector construction; investigations were made with available films of plastic scintillators. Experimental investigations have shown that by using coincidence techniques, plastic scintillator films can be used as a single volume 'microdosimeter', that is as counters of single strand breaks. Its use as a single volume 'nanodosimeter' is handicapped by light losses in the detector assembly which reduces the detector's sensitivity, efficiency and resolution. Semi-empirical analysis showed that the production of light from a phosphor differs fundamentally from the induction of biological damage. It was inferred that the plastic scintillators are unsuitable for instrumentation of the proposed system of dosimetry. Suggestions for future investigations were made.
2
CECATTI, SONIA G. P. "Desenvolvimento de sistemas tandem de activimetros e estabelecimento de dosimetria beta em servicos de medicina nuclear." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11203.
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GERULIS, EDUARDO. "Controle da dose de radiação ionizante para trabalhadores em uma instalação radiativa con fontes não-seladas." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11408.
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ALVES, ALICE dos S. "Estudo dos agentes de risco ocupacional e seus prováveis agravos na saúde humana." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/25321.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-12-17T09:17:56Z
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5
Coupier, B. "Studies towards the understanding of the effects of ionizing radiations at the molecular scales (20 to 150 keV H+/H + He Collisions; Dissociative Electron Attachment to Water)." Phd thesis, Université Claude Bernard - Lyon I, 2005. http://tel.archives-ouvertes.fr/tel-00012069.
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Ce travail s'inscrit dans le cadre d'études récentes pour la compréhension à l'échelle moléculaire des effets des rayonnements ionisants sur les systèmes biologiques, mises en oeuvre par le groupe IPM de l'IPNL en collaboration avec l'Institut für Ionenphysik de l'Université d'Innsbruck. Il est composé de deux parties. La première présente un nouvel ensemble de mesures des sections efficaces d'ionisation de l'hélium par impact de protons ou d'atomes d'hydrogène dans la gamme d'énergie d'intérêt pour la radiobiologie (20 à 150keV). Il s'agit de systèmes modèles d'intérêt pour la compréhension des phénomènes de base, et les collisions H + He ont fait l'objet, jusqu'à présent, de peu d'études utilisant les techniques de coïncidences. En outre, cette étude avec l'hélium a été faite dans l'intention de réaliser un test général de fonctionnement de l'appareillage avant d'aller vers des systèmes plus complexes. Des études similaires ont été ensuite réalisées en remplaçant la cible d'hélium par l'eau ou par des molécules d'intérêt biologique (Uracil, Thymine ...). La seconde partie de la thèse traite d'un autre type de radiations ionisantes que l'on peut voir comme une des conséquences secondaires des radiations étudiées dans la première partie. Des électrons de faible énergie (1 à 16eV) sont émis lors du bombardement de la matière par des protons ou des atomes d'hydrogène rapides; ces électrons ayant à leur tour des effets ionisants sur l'environnement. Une étude de l'attachement dissociatif des électrons sur l'eau a été entreprise à l'université d'Innsbruck, motivée par l'existence d'importants désaccords entre les précédentes études sur le même sujet. Le problème de la discrimination des ions à grande énergie cinétique dans le monochromateur trochoïdal utilisé pour cette étude a fait l'objet d'une attention particulière.
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Dutra, Patrícia Maria Barragán Frattezi. "Percepção de estudantes do ensino médio sobre o tema radiação e tecnologias relacionadas: ideias informais e categorias conceituais." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2010. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=162.
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Nenhuma<br>A radiação e suas tecnologias geram reações de medo e ansiedade em diferentes comunidades, pois é comum que esses temas estejam relacionados aos seus efeitos negativos como os acidentes, as bombas atômicas e o câncer. Apesar disso, os avanços tecnológicos e as discussões envolvendo a utilização das radiações têm se tornado cada vez mais importantes a despeito da percepção pública permanecer suportada pelo senso comum.
As ideias sobre radiação estão inseridas na discussão de riscos, como um problema de preocupação pública, pois como não é compreendida, gera somatização dos medos, preconceitos e insegurança na população. Os tópicos mais recorrentes na literatura envolvem a saúde dos seres humanos: radiação solar, acidentes radiológicos, energia nuclear e campos eletromagnéticos da tecnologia de telefonia móvel. A OMS (Organização Mundial de Saúde) demonstra preocupações em estudar e esclarecer à população quanto a esse último tema, pois ele tem se firmado como ponto de discussão de saúde pública internacional.
Partindo dessas discussões, é interessante que a abordagem sobre os temas seja dialógica, isto é, as ideias informais do leitor inseridas na comunicação. Assim, é preciso conhecer o pensamento da população, no caso deste trabalho, dos estudantes de ensino médio, sobre o tema e como se relacionam com as situações abordadas. A partir do questionário elaborado foram levantadas as ideias apresentadas e a forma como elas influenciam suas decisões nas situações propostas. Esse trabalho, então, investigou como se pensa o conceito de radiação, a forma que se lida com tecnologias e situações relacionadas e, também, organizou e analisou essas ideias para formar as bases para uma abordagem dialógica sobre radiação e assuntos relacionados.
A partir dos resultados, foi possível perceber que os estudantes associam a ideia de radiação à ondas eletromagnéticas e raios como os do sol. Contudo, essa visão não foi utilizada por eles na avaliação das situações-problema propostas, ou seja, eles não recorreram a esses conceitos para julgar as situações. Nas afirmações dos alunos é possível perceber que a apresentação de informações sobre os assuntos foi positivamente aceita, pois eles se embasaram nelas para responder ou contestar as questões.
7
SOUZA, DIVANIZIA do N. "Caracterizacao do topazio natural para aplicacoes dosimetricas na faixa terapeutica." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11074.
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ACAR, MARIA E. D. "Modelagem sociotécnica de uma organização nuclear: estudo de caso aplicado ao laboratório Nacional de Metrologia das Radiações Ionizantes." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/25358.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-12-22T09:33:02Z
No. of bitstreams: 0<br>Made available in DSpace on 2015-12-22T09:33:02Z (GMT). No. of bitstreams: 0<br>Tese (Doutorado em Tecnologia Nuclear)<br>IPEN/T<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Ben, Krit Sabrine. "Etude et développement d’une chaine de traitement analogique du signal dédiée à la détection de particules en environnement sévère." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4388.
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Le travail présenté dans ce mémoire est basé sur l’étude et le développement d’une chaine analogique de traitement du signal destinée à la détection de particules issues d’un réacteur nucléaire. Le détecteur de radiations relatif à cette chaine, étant placé au cœur du réacteur (hautes températures et radiations), deux scénarii d’intégration de la chaine analogique en environnement sévère ont été étudiés. Tandis que le premier scénario consiste à placer le préamplificateur et l’amplificateur de mise en forme loin du détecteur, le deuxième est basé sur l’intégration de ces blocs analogiques en environnement contraint. Bien que le premier scénario ait démontré de bonnes performances en termes de linéarité et sensibilité, l’amélioration de la résolution digitale fournie par le système nous a mené à investiguer le placement de la chaine tout près du détecteur. Plusieurs études, basées sur l’évaluation de la fiabilité de la structure vis-à-vis des contraintes de l’environnement sévère ont été donc élaborées. De plus une solution innovante permettant une meilleure caractérisation de la particule incidente a été présentée et détaillée<br>The work presented in this thesis is based on the study and development of an analog processing chain dedicated to the detection of particles delivred from a nuclear reactor. The radiation detector related to this chain, being placed at the heart of the reactor (high temperatures and radiation flux), two scenraii related to the integration of the analog chain in harsh environment were studied. While the first scenario consists on placing the preamplifier and the shaping amplifier away from the detector, the second is based on the integration of these analog blocks in harsh environment. Although the first scenario has proven good performances in terms of linearity and sensitivity, the improvement of the digital resolution provided by the system leaded us to investigate the placement of the chain close to the detector. Several studies based on the evaluation of the structure reliability under harsh environment constraints were thus elaborated. In addition, an innovative solution providing better characterization of the incident particle was presented and detailed
10
Weulersse, Cécile. "Développement et validation d’outils Monte-Carlo pour la prédiction des basculements logiques induits par les radiations dans les mémoires Sram très largement submicroniques." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20221.
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Les particules de l'environnement radiatif naturel sont responsables de dysfonctionnements dans les systèmes électroniques. Dans le cas d'applications critiques nécessitant une très haute fiabilité, il est primordial de répondre aux impératifs de sûreté de fonctionnement. Pour s'en assurer et, le cas échéant, dimensionner les protections de manière adéquate, il est nécessaire de disposer d'outils permettant d'évaluer la sensibilité de l'électronique vis-à-vis de ces perturbations.L'objectif de ce travail est le développement d'outils à destination des ingénieurs pour la prédiction des aléas logiques induits par les radiations dans les mémoires SRAM. Dans un premier temps, des bases de données de réactions nucléaires sont construites à l'aide du code de simulation Geant4. Ces bases de données sont ensuite utilisées par un outil Monte-Carlo dont les prédictions sont comparées avec des résultats d'irradiations que nous avons effectuées sur des mémoires SRAM en technologie 90 et 65 nm. Enfin, des critères simplifiés reposant sur une amélioration de la méthode SIMPA nous permettent de proposer un outil d'ingénieur pour la prédiction de la sensibilité aux protons ou aux neutrons à partir des données expérimentales ions lourds. Cette méthode est validée sur des technologies de SRAM très largement submicroniques et permet l'estimation des évènements multiples, une problématique croissante pour les applications spatiales, avioniques et terrestres<br>Particles from natural radiation environment can cause malfunctions in electronic systems. In the case of critical applications involving a very high reliability, it is crucial to fulfill the requirements of dependability. To ensure this and, if necessary, to adequately design mitigations, it is important to get tools for the sensitivity assessment of electronics towards radiations.The purpose of this work is the development of prediction tools for radiation-induced soft errors, which are primarily intended for end users. In a first step, the nuclear reaction databases were built using the Geant4 toolkit. These databases were then used by a pre-existing Monte-Carlo tool which predictions were compared with experimental results performed on 90 and 65 nm SRAM devices. Finally, simplified criteria enabled us to propose an engineering tool for the prediction of the proton or neutron sensitivity from heavy ion data. This method was validated on deep submicron devices and allows the user to estimate multiple events, which are a crucial issue in space, avionic and ground applications
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Rosado, Paulo Henrique Gonçalves. "Determinação experimental dos coeficientes de conversão de Kerma no ar para o equivalente de dose pessoal, Hp(d), e fatores de retroespalhamento em feixes de raios-x diagnostico." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2008. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=86.
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Em proteção radiológica dois conjuntos de grandezas são importantes, as de proteção e as operacionais. Ambas podem ser relacionadas a partir de coeficientes de conversão
com grandezas físicas básicas como o kerma. Para feixes de radiação utilizados em radiodiagnóstico nas qualidades da Comissão Internacional de Eletrotécnica (IEC), os
coeficientes de conversão e fatores de retroespalhamento ainda não foram determinados.
É, portanto, necessário a determinação de coeficientes e fatores para a calibração dos dosímetros que serão utilizados para determinar o equivalente de dose pessoal ou a dose
na entrada da pele.
Foram determinados experimentalmente os coeficientes de conversão de kerma no ar para o equivalente de dose pessoal, Hp(d), e os fatores de retroespalhamento para as
qualidades RQR e RQA da IEC que simulam feixes de raios X diagnósticos. Para a determinação dos coeficientes de conversão é necessário a determinação do kerma no ar
dentro do simulador e a energia média do espectro.
Foram utilizados dosímetros termoluminescentes do tipo 100H para a medida do kerma no ar no simulador. Os dosímetros foram calibrados utilizando uma câmara de ionização
padrão terciário de 180cc da Radcal Corporation. Os dosímetros foram colocados no eixo central de um simulador tipo placa de 300 mm x 300 mm x 15 mm de polimetilmetalacrilato (PMMA) com o intuito de determinar a dose na profundidade.
No procedimento de medida os dosímetros foram dispostos em cinco diferentes profundidades (5, 10, 15, 25 e 35 mm).
Um outro parâmetro necessário para a determinação dos coeficientes de conversão é a energia média do espectro de raios X. A espectrometria dos feixes de raios X utilizados
foi feita utilizando um detector semicondutor de CdTe. O detector foi calibrado utilizando fontes de radiação de 133Ba, 241Am e 57Co. Foram feitas correções em relação a eficiência intrínseca, absorção total de energia, fração de escape de raios X característicos, efeito Compton e atenuação devido a matérias que se encontravam entre o detector e o ponto onde foi determinado a energia média. As medidas do espectro de raios X foram corrigidas utilizado o método de stripping.
Os valores das incertezas dos coeficientes de conversão e fatores de retroespalhamento foram da ordem de 12% e 6% respectivamente.<br>Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. . For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose.
Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and
RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such
purpose.
Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm3 Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm ×300 mm × 150 mm
polymethilmethacrylate (PMMA) slab phantom was used for deep-dose measurements.
Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the
mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with 133Ba, 241Am and 57Co radiation
sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption,
escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured
x-ray spectra were corrected with the stripping method by using these response functions.
The typical combined standard uncertainties of conversion coefficients and backscatter factors were 12% and 6% respectively.
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Belloir, Jean-Marc. "Spectroscopie du courant d’obscurité induit par les effets de déplacement atomique des radiations spatiales et nucléaires dans les capteurs d’images CMOS à photodiode pincée." Thesis, Toulouse, ISAE, 2016. http://www.theses.fr/2016ESAE0029/document.
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Les imageurs CMOS représentent un outil d’avenir pour de nombreuses applications scientifiques de haut vol, tellesque l’observation spatiale ou les expériences nucléaires. En effet, ces imageurs ont vu leurs performancesdémultipliées ces dernières années grâce aux avancées incessantes de la microélectronique, et présentent aussi desavantages indéniables qui les destinent à remplacer les CCDs dans les futurs instruments spatiaux. Toutefois, enenvironnement spatial ou nucléaire, ces imageurs doivent faire face aux attaques répétées de particules pouvantrapidement dégrader leurs performances électro-optiques. En particulier, les protons, électrons et ions présents dansl’espace ou les neutrons de fusion nucléaire peuvent déplacer des atomes de silicium dans le volume du pixel et enrompre la structure cristalline. Ces effets de déplacement peuvent former des défauts stables introduisant des étatsd’énergie dans la bande interdite du silicium, et ainsi conduire à la génération thermique de paires électron-trou. Parconséquent, ces radiations non-ionisantes produisent une augmentation permanente du courant d’obscurité despixels de l’imageur et donc à une diminution de leur sensibilité et de leur dynamique. L’objectif des présents travauxest d’étendre la compréhension des effets de déplacement sur l’augmentation du courant d’obscurité dans lesimageurs CMOS. En particulier, ces travaux se concentrent sur l’étude de la forme de la distribution de courantd’obscurité en fonction du type, de l’énergie et du nombre de particules ayant traversé l’imageur, mais aussi enfonction des caractéristiques de l’imageur. Ces nombreux résultats permettent de valider physiquement etexpérimentalement un modèle empirique de prédiction de la distribution du courant d’obscurité pour une utilisationdans les domaines spatial et nucléaire. Une autre partie majeure de ces travaux consiste à utiliser pour la première foisla technique de spectroscopie de courant d’obscurité pour détecter et caractériser individuellement les défautsgénérés par les radiations non-ionisantes dans les imageurs CMOS. De nombreux types de défauts sont détectés etdeux sont identifiés, prouvant l’applicabilité de cette technique pour étudier la nature des défauts cristallins généréspar les effets de déplacement dans le silicium. Ces travaux avancent la compréhension des défauts responsables del’augmentation du courant d’obscurité en environnement radiatif, et ouvrent la voie au développement de modèles deprédiction plus précis, voire de techniques permettant d’éviter la formation de ces défauts ou de les faire disparaître<br>CMOS image sensors are envisioned for an increasing number of high-end scientific imaging applications such asspace imaging or nuclear experiments. Indeed, the performance of high-end CMOS image sensors has dramaticallyincreased in the past years thanks to the unceasing improvements of microelectronics, and these image sensors havesubstantial advantages over CCDs which make them great candidates to replace CCDs in future space missions.However, in space and nuclear environments, CMOS image sensors must face harsh radiation which can rapidlydegrade their electro-optical performances. In particular, the protons, electrons and ions travelling in space or thefusion neutrons from nuclear experiments can displace silicon atoms in the pixels and break the crystalline structure.These displacement damage effects lead to the formation of stable defects and to the introduction of states in theforbidden bandgap of silicon, which can allow the thermal generation of electron-hole pairs. Consequently, nonionizingradiation leads to a permanent increase of the dark current of the pixels and thus a decrease of the imagesensor sensibility and dynamic range. The aim of the present work is to extend the understanding of the effect ofdisplacement damage on the dark current increase of CMOS image sensors. In particular, this work focuses on theshape of the dark current distribution depending on the particle type, energy and fluence but also on the imagesensor physical parameters. Thanks to the many conditions tested, an empirical model for the prediction of the darkcurrent distribution induced by displacement damage in nuclear or space environments is experimentally validatedand physically justified. Another central part of this work consists in using the dark current spectroscopy techniquefor the first time on irradiated CMOS image sensors to detect and characterize radiation-induced silicon bulk defects.Many types of defects are detected and two of them are identified, proving the applicability of this technique to studythe nature of silicon bulk defects using image sensors. In summary, this work advances the understanding of thenature of the radiation-induced defects responsible for the dark current increase in space or nuclear environments. Italso leads the way to the design of more advanced dark current prediction models, or to the development ofmitigation strategies in order to prevent the formation of the responsible defects or to allow their removal
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Ngwetsheni, Cebo. "Polarizability effects due to low-energy enhancement of the gamma-strength function." University of the Western Cape, 2018. http://hdl.handle.net/11394/6705.
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>Magister Scientiae - MSc<br>Physics is the study of natural phenomena. Nuclear physicists have since the
discovery of the nucleus been working on understanding its dynamics. The nuclear
chart, analogous to the periodic table of elements, is illustrated in Fig. 1.1
and color coded according to decay modes. Several theoretical models, based
on various hypothesis, have been developed during the years in order to understand
nuclear phenomena such as nucleon-nucleon (n-n) interactions, binding
energies, radii, excited states, etc. Unfortunately, no-unique model is actually
able to grasp all nuclear phenomena at the desired level of accuracy.
Among the di erent models, we notice that two distinct hypotheses can be used
to describe nuclear properties. Firstly, the independent particle shell model
(IPSM) + the n-n residual interaction, which assumes that a nucleon moves
independently in a potential generated by other nucleons. Secondly, the macroscopic
models, where a nucleus is considered as a whole, i.e. neutrons and protons
behave cooperatively and are mutually coupled to each other; highlighting
the short-ranged character of the nuclear force. The liquid-drop model is an example
of such macroscopic models. Re nement of these models is dependent on
experimental observations that are better detailed for nuclei along the line of -
stability, making up a small fraction of the known isotopes, as shown in Fig. 1.1.
In practice, various techniques for studying exotic nuclei up to neutron and
proton drip-lines have been devised, including the use of radioactive ion beams.
However, the main challenges are the synthesization and short lived periods
of these exotic nuclei resulting in insu cient data collection from which the
characteristics and structural information are extracted. In general, nuclei have
unique structures represented by a particular con guration as given by the shell
model (SM). These structures impact a number of physical quantities, e.g. transition
probabilities, cross sections and photon-strength functions. Experimental
methods such as Coulomb excitation or electromagnetic radiation are used to
probe these structures without invoking the nuclear force.
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Rizzolo, Serena. "Advantages and limitations of distributed optical-frequency-domain-reflectometry for optical fiber-based sensors in harsh environments." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES013.
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L’accident de Fukushima-Daiichi du 11 Mars 2011 a fortement marqué l'industrie nucléaire en mettant en évidence plusieurs faiblesses dans le contrôle des systèmes critiques qui assurent la sécurité des centrales nucléaires, en particulier, lors de conditions accidentelles. Cette thèse a été réalisée en collaboration avec AREVA, groupe industriel français actif dans le domaine de l'énergie, avec l’objectif de réaliser des capteurs à fibres optiques résistants aux contraintes sévères d'une centrale nucléaire et, en particulier, de surveiller la température et le niveau de l'eau à l'intérieur d’une piscine de stockage de combustible. La thèse est composée de deux parties organisées en 7 chapitres. Dans la première partie, le chapitre 1 traite des phénomènes contribuant à l'atténuation de la lumière au cours de sa propagation dans la fibre et donne un aperçu des effets des radiations sur les fibres optiques. Pour identifier la technique la plus prometteuse adaptée aux applications visées par AREVA, le chapitre 2 propose un état de l’art sur les capteurs distribués à fibres optiques existants avec une attention particulière à leur emploi dans des environnements radiatifs. La dernière partie de ce chapitre est consacrée à la description détaillée de l’OFDR qui est la technique retenue pour cette application. La deuxième partie est consacrée à la présentation des résultats obtenus et leur analyse. Le chapitre 3 présente le détail des irradiations et des traitements thermiques, les échantillons retenus et les bancs de mesure utilisés. Afin de déterminer la meilleure combinaison fibre/technique par rapport à l’application visée, une étude systématique des capteurs distribués de température et de contrainte a été réalisée. Les effets permanents des rayonnements (niveaux de dose du MGy) sont étudiés dans le chapitre 4. Le chapitre 5 illustre des mesures in situ sur les fibres résistantes aux radiations pour comprendre les effets combinés de la température et des radiations (rayons X), effets représentatifs des conditions nominales et accidentelles des piscines de stockage. Enfin, nous avons développé un prototype de capteur de niveau d’eau pour les piscines de combustible qui est décrit dans le chapitre 6. Ensuite, les principales conclusions et les perspectives de ce travail de thèse sont discutées<br>Fukushima-Daiichi event on March 11th, 2011, signed a turning point in nuclear industry by highlighting several weaknesses in the control of critical systems that ensure the safety in nuclear power plant (NPP) operating, particularly, in accidentals conditions. This PhD thesis has been carried out in collaboration with AREVA, the French industrial group active in the energy domain, with the aim of realizing optical fiber sensors resistant to the harsh environment constraints of a NPP and, in particular, to monitor temperature and water level several parameters inside the spent fuel pools (SFPs). It consists of two parts organized in 7 chapters. In the first part, chapter 1 deals with the phenomena contributing to the light attenuation during its propagation along the fiber and gives an overview on the radiation effects on optical fibers. To identify the most promising technique suitable for AREVA needs, in chapter 2 is reported the state-of-the-art on the distributed OFSs with particular attention to their employment in radiation environments. The last part of this chapter is devoted to the detailed description of the OFDR that is the selected sensor technique for this application. The second part is devoted to present and discuss the obtained results. Chapter 3 gives the experimental details on radiation and thermal treatments, investigated samples and used setups. In order to determine the best fiber/setup combination, a systematic study on temperature and strain distributed sensors was carried out in relation to the harsh constraints demanded from the application. The permanent radiation (MGy dose levels) effects on different fiber classes are investigated in Chapter 4. Chapter 5 illustrates in situ measurements on radiation resistant fibers to understand the combined temperature and radiation (X-rays) effects representative of the SFP nominal and accidental conditions. Simultaneously, we have developed the OFS design for its integration at SFP facility. The prototype is described and its performance is evaluated in chapter 6. Then, the main conclusion and perspective are discussed<br>L'incidente di Fukushima-Daiichi dell’11 marzo 2011 ha segnato un punto di svolta per l’industria nucleare, mettendo in evidenza diversi punti deboli nel controllo di sistemi critici che garantiscono la sicurezza nelle centrali, in particolare in condizioni di incidente. Questa tesi è stata condotta in collaborazione con AREVA, il gruppo industriale francese attivo nel settore dell'energia, con l'obiettivo di produrre sensori a fibra ottica resistenti alle condizioni estreme di una centrale nucleare e, in particolare, per controllare diversi parametri all'interno di una piscina di stoccaggio di combustibile nucleare, quali la temperatura e il livello dell'acqua. La tesi si compone di due parti organizzate in 7 capitoli. Nella prima parte, il capitolo 1 riguarda i fenomeni che contribuiscono all'attenuazione della luce durante la sua propagazione nella fibra e permette di comprendere gli effetti della radiazione sulle fibre ottiche. Per identificare la tecnologia più promettente per le esigenze di AREVA, nel capitolo 2 é discusso lo stato dell’arte sui sensori distribuiti con particolare attenzione alle loro performance in ambienti radiativi. L'ultima parte di questo capitolo è dedicato ad una descrizione dettagliata della tecnica OFDR che è la tecnologia scelta per questa applicazione. La seconda parte è dedicata a presentare e discutere i risultati. Il capitolo 3 fornisce i dettagli sui campioni studiati e i trattamenti effettuati su di essi e descrive il setup utilizzato. Per determinare la migliore combinazione fibra/tecnica per l’applicazione prevista, è stato eseguito uno studio sistematico sulla risposta alla radiazione dei sensori distribuiti di temperatura e strain. Glieffetti permanenti della radiazione (dosi dell’ordine del MGy) su diverse classi di fibre, resistenti e sensibili alle radiazioni, sono discussi nel capitolo 4. Il capitolo 5 riporta le misure in situ sulle fibre resistenti alla radiazione per investigare gli effetti combinati di temperatura e radiazioni (raggi X) rappresentativi delle condizioni operative e accidentali nelle piscine di stoccaggio. Infine, abbiamo sviluppato un prototipo di sensore del livello dell’acqua nelle piscine di stoccaggio che è descritto nel capitolo 6. In seguito, le principali conclusioni e le prospettive sono discusse
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Norman, Ryan Bradley. "Resonance production and nuclear fragmentation for space radiation." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-042208-131402/.
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Dissertation (Ph.D.)--Worcester Polytechnic Institute.<br>Keywords: nuclear physics, particle physics, phyiscs, resonance, nuyclear fragmentation, nucleon-nucleon interactions, radiation shileding, heavy-ion physics, space radiation. Includes bibliographical references (leaves 163-141).
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Le, Foulher Fabrice. "Simulations Monte Carlo et mesures de l’émission de gamma prompts appliquées au contrôle en ligne en hadronthérapie." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10180/document.
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Au cours du traitement d'une tumeur avec des ions légers, la position du pic de Bragg doit être connue avec précision. Une fraction importante des ions incidents subissent des collisions nucléaires avec les noyaux cibles conduisant à l'émission de particules promptes qui peuvent être porteuses d'informations sur le parcours des ions. Ce travail, qui se concentre sur les gamma prompts, montre que le rendement en profondeur de ces émissions est fortement corrélé au parcours des ions et que les taux de comptage mesurés permettent d'envisager un système d'imagerie réaliste, fonctionnant en temps réel. Dans ce but, nous avons réalisé des expériences au GANIL et au GSI avec un détecteur collimaté placé perpendiculairement à l'axe du faisceau et la technique du temps de vol a été utilisée pour réduire le bruit de fond induit par les neutrons et les particules chargées. Des simulations Geant4 ont été réalisées pour concevoir le dispositif expérimental et interpréter les données. Un accord qualitatif entre les simulations et l'expérience est observé pour la quantité d'énergie déposée dans le détecteur et pour la forme du spectre de temps de vol. Cependant, des divergences apparaissent pour le rendement de gamma prompts et la distribution en profondeur des gamma détectés. Ces divergences sont discutées, principalement en termes de modèles de physique nucléaire qui doivent être améliorés. Après avoir sélectionné les modèles physiques offrant les simulations les plus en accord avec les mesures, des études concernant les lieux d'émissions des gamma prompts et l'influence de la diffusion dans la cible ont été réalisés afin de déterminer l'impact sur la corrélation avec le parcours des ions<br>During the treatment of a tumor with light ions, the Bragg peak location must be accurately known. A significant fraction of the incident ions undergo nuclear collisions with the target nuclei leading to the prompt emission of particles which may carry information on the ion path. This work, which focuses on prompt gamma, shows that the depth profile of these emissions is highly correlated to the ions path and the measured counting rates allow to consider a realistic imaging system, operating in real time. For that purpose, we performed experiments at GANIL and at GSI with a collimated detector placed perpendicular to the beam axis and the time of flight technique was used in order to reduce the noise induced by neutrons and charged particles. Geant4 simulations were performed for the experimental design and data interpretation. A qualitative agreement between simulations and experiment is observed for the amount of energy deposited in the detector and the shape of the time of flight spectrum. However, discrepancies appear for the prompt gamma yield and the depth distribution of gamma detected. These discrepancies are discussed, mainly in terms of nuclear physics models that must be improved. After selecting the physical models which lead to the best agreement between simulations and measurements, studies on the location of prompt gamma emission and on the influence of diffusion in the target were performed to determine the impact on the correlation with the ion path
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Masuda, Ryo. "Dependence of incoherent nuclear resonant scattering of synchrotron radiation on the number of resonant nuclei." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136766.
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Priestley, Rebecca Katherine. "Nuclear New Zealand: New Zealand's nuclear and radiation history to 1987." Thesis, University of Canterbury. School of Humanities, 2010. http://hdl.handle.net/10092/5007.
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New Zealand has a paradoxical relationship with nuclear science. We are as proud of Ernest Rutherford, known as the father of nuclear science, as of our nuclear-free status. Early enthusiasm for radium and X-rays in the first half of the twentieth century and euphoria in the 1950s about the discovery of uranium in a West Coast road cutting was countered by outrage at French nuclear testing in the Pacific and protests against visits from American nuclear-powered warships.
New Zealand today has a strong nuclear-free identity – a result of the New Zealand Nuclear Free Zone, Disarmament and Arms Control Act of 1987 that prohibited nuclear weapons and nuclear warships in the country’s land, air and water – that can be traced back to the first protests against nuclear weapons in the 1940s. This thesis is based on the supposition that the “nuclear-free New Zealand” narrative is so strong and such a part of the national identity that it has largely eclipsed another story, the pre-1980s story of “nuclear New Zealand”. New Zealand’s early embracing of and enthusiasm for nuclear science and technology needs to be introduced into our national story. This thesis aims to discover and reveal that history: from the young New Zealand physicists seconded to work on the Manhattan Project; to the plans for a heavy water plant at Wairakei; prospecting for uranium on the West Coast of the South Island; plans for a nuclear power station on the Kaipara Harbour; and the thousands of scientists and medical professionals who have worked with nuclear technology. Put together, they provide a narrative history of nuclear New Zealand.
Between the “anti-nuclear” voices, already well told in many histories of nuclear-free New Zealand, and the “pro-nuclear” voices revealed in this thesis, options were considered and decisions made. This thesis shows that the people with decision-making power tended to make practical decisions based on economics and national interest when it came to deciding whether or not to adopt a certain piece of nuclear technology or whether or not to participate in projects or ventures with international agencies. This eventually led to a nuclear-free policy – focused on weapons, nuclear-powered ships and waste – that since the legislation was enacted in 1987 has been interpreted ever more widely by politicians and the public to include nuclear power, uranium prospecting and many other applications of nuclear technology.
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Jansson, Peter. "Studies of Nuclear Fuel by Means of Nuclear Spectroscopic Methods." Doctoral thesis, Uppsala University, Department of Nuclear and Particle Physics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2057.
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<p>The increasing demand for characterization of nuclear fuel, both from an operator and authority point of view, motivates the development of new experimental and, preferable, non-destructive methods. In this thesis, some methods based on nuclear spectroscopic techniques are presented.</p><p>Various parameters of irradiated fuel are shown to be determined with high accuracy and confidence by utilizing gamma-ray scanning, tomography and passive neutron assay.</p><p>Specifically, fuel parameters relevant for a secure storage of spent nuclear fuel in a long-term repository, such as e.g. burnup and decay heat, are shown to be determined with adequate accuracy. The techniques developed are expected to be implemented in the planned encapsulation facility in Sweden.</p><p>Also, a device for tomographic measurements of the spatial distribution of thermal power in nuclear fuel assemblies has been built, tested and evaluated. The device utilizes single photon emission computed tomography (SPECT) in order to reconstruct the gamma-ray source distribution within a fuel assembly. The device is expected to be an important tool for validating reactor core simulators regarding new fuel designs.</p><p>For safeguards purposes, two experimental methods for verifying the integrity, i.e. the possible loss of fissile material from a nuclear fuel assembly, are presented. Verification of integrity is shown to be possible on an individual fuel rod level.</p>
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White, Ryan D. "A high-altitude nuclear environment simulation." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2315.
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Podgorsak, Matthew B. "Fricke radiation dosimetry using nuclear magnetic resonance." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59290.
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The spin-lattice relaxation rate R$ sb1$ of irradiated Fricke solution was studied as a function of the absorbed dose D. The R$ sb1$ increases linearly with D up to a dose of $ sim$250 Gy after which the response saturates. A model describing the R$ sb1$ of a solution of either ferrous (Fe$ sp{2+})$ or ferric (Fe$ sp{3+})$ ions is presented; it is based on fast exchange between protons on water molecules in the bulk and protons on water molecules in the coordination shell of the ions. All inherent relaxation parameters of the different proton groups are determined. An extension of the model is made to describe the spin-lattice relaxation behaviour of irradiated Fricke solution. Good agreement between model predictions and experimental results is observed. The model relates the spin-lattice relaxation rate of a Fricke dosimeter to the chemical yield of ferric ion, thus creating an absolute dosimetry technique. Various practical aspects of the NMR-Fricke system are described.
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Holcomb, David Eugene. "Optical fibers in nuclear reactor radiation environments /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487759914759614.
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Schofield, Jennifer. "Effects of ionising radiation on nuclear materials." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/effects-of-ionising-radiation-on-nuclear-materials(96d2e6da-6237-4fd2-b46e-6ac3370caf8e).html.
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The prediction of energy loss properties and track structure effects of ionising radiation in materials is of importance to many areas of science, healthcare and technology, especially the nuclear industry. This study examines three different aspects of the electronic effects of ionising radiation on solid materials: the calculation of inelastic cross sections, the measurement of charge state fractions of ions through materials, and the radiolytic hydrogen produced from slurries under gamma irradiation. Predicting how ionising radiation will interact with matter often utilises collision cross sections for the interaction process. The electronic energy loss cross sections of ions in materials are predicted using a novel formalism requiring only the dipole oscillator strength distribution (DOSD) of the material of interest. DOSDs are constructed for silicon carbide and various oxides of interest to the nuclear industry. Electronic collision cross sections as well as average energy loss properties for incident protons, helium and other ions are calculated using the developed formalism. The formalism is shown to predict macroscopic energy loss properties well, especially at higher energies, suggesting the formalism is an acceptable simple yet elegant method for calculating electronic cross sections for use in Monte Carlo simulations of radiation track structures. The charge of an ion in a material affects the rate of energy loss during the passage through that material. The charge state fractions of lithium and helium ions in several metallic materials pertinent to the nuclear industry are measured and compared in order to improve the understanding of ion charge states in a radiation track structure. The new charge state fraction measurements show a clear dependence on material properties which appears to correlate with the ionisation potential of the material; however, a full understanding of the dependence is lacking. Radiolytic hydrogen production is of importance when considering the safety of spent nuclear material in cooling ponds and after disposal. One proposed clad coating for accident tolerant fuel currently under investigation is silicon carbide however its radiation chemistry is relatively unknown. The hydrogen produced from gamma-irradiated silicon carbide water slurries is investigated. The measured yield of H2 produced is greater than would be expected from a mixture rule. This excess production of H2 is believed to be due to transfer of energy from the solid ceramic to the aqueous phase by either low energy electrons or exciton dissociation at the water-carbide interface. These three areas of investigation are complementary aspects of the interaction of ionising radiation with solid material and add to the knowledge base necessary for an acceptable risk-based justification for sustainable energy production by nuclear fission power plants.
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Williams, Richard B. Sc D. Massachusetts Institute of Technology. "Adaptive multigroup radiation diffusion." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34430.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005.<br>Includes bibliographical references (p. 189-193).<br>This thesis describes the development and implementation of an algorithm for dramatically increasing the accuracy and reliability of multigroup radiation diffusion simulations at low group counts. This is achieved by allowing the energy group boundaries to move in energy space as the simulation evolves. This adaption in energy space effectively removes the sensitivity of multigroup diffusion to group boundary placement and makes the technique a viable option for large, computationally expensive computer simulations. Traditional multigroup radiation diffusion solvers break down at small group counts because of the coarse discretization of highly nonlinear material opacity. Small changes in the group boundary energies can lead to wildly different mean opacities and therefore significant changes in simulation output. This sensitivity has rendered the technique unpredictable and it is generally considered to be not worth the added computational expense. Unfortunately, multigroup diffusion is the only method available for adding frequency dependence to the radiation field in a standard diffusion solver. When attempting to model a system that includes a non-equilibrium radiation field, frequency-dependent effects become important.<br>(cont.) While running multigroup simulations with large numbers of groups is a reliable method for obtaining increased accuracy over grey diffusion, the computational expense scales linearly with the number of groups. For large simulations, running multigroup diffusion with increased group counts is infeasible and running with small group counts is unreliable. This has led to a tendency to use grey diffusion even in environments where the radiation field is known to be out of equilibrium with the material. This thesis includes a new derivation of the diffusion equation and an overview of traditional "static" multigroup radiation diffusion along with an analysis of its shortcomings. The sensitivity due to group boundary placement for small numbers of groups is shown. Data are presented which demonstrate that small group count multigroup calculations can actually provide a worse answer than grey diffusion. A system is developed and implemented for allowing the multigroup energy boundaries to "adapt," or move in energy space, as the simulation evolves as well as a method for determining where increased energy resolution is needed for an arbitrary set of material opacities. By adapting in energy space, the sensitivity of multigroup diffusion to group boundary placement is ameliorated.<br>(cont.) Data are presented that demonstrate a reliable increase in accuracy for adaptive multigroup diffusion as the number of groups is increased-even at very small group counts. Furthermore, the data show that the level of accuracy obtained with the adaptive multigroup approach is equivalent to or better than the best-case data obtained with the static multigroup approach. This result is more profound than a simple increase in accuracy-the increased reliability makes multigroup radiation diffusion a viable tool for large non-equilibrium simulations. Users are no longer forced to use the grey diffusion method which is known to be physically inadequate. Furthermore, users are finally free to incorporate a frequency-dependent treatment of radiation without the accuracy ambiguities of standard multigroup diffusion.<br>by Richard B. Williams.<br>Sc.D.
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Elie, Margaux. "Développement de nouveaux complexes organométalliques de métaux de transition polyvalents pour la scintillation et la chimie médicinale." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC227.
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Deux nouvelles familles de complexes de cuivre(I) cationiques, de formules [Cu(NHC)(N^N)][X] et [Cu(P^P)(N^N)][PF6], ont été synthétisées avec des ligands 2,2’ bis pyridyl pontés, chélates à six chaînons, facilement modulables. Ces complexes présentent des émissions à l’état solide centrées entre 455 et 520 nm (bleu à vert), avec de larges décalages de Stokes et des rendements quantiques pouvant atteindre 0,86. De plus, l’émission via un phénomène de fluorescence retardée activée thermiquement (TADF) a été prouvée pour les complexes [Cu(NHC)(N^N)][X]. Les premiers scintillateurs plastiques dopés avec des complexes de cuivre(I) détectant les radiations nucléaires de type gammas ont été obtenus avec des complexes de formule générale [Cu(P^P)(N^N)][PF6]. Les complexes de formule [Cu(NHC)(N^N)][X] ont permis l’obtention des premières Cellules Electrochimiques Luminescentes (LECs) émettant dans le bleu et incorporant des complexes de cuivre(I). Enfin, les complexes de formule [Cu(NHC)(N^N)][X] à ligand 2,2’ dipyridylamine présentent une activité cytotoxique envers différentes lignées de cellules cancéreuses et apportent la possibilité d’une action ciblée sur les cellules tumorales via l’ajout d’un vecteur. La polyvalence de ces complexes de cuivre(I) repose sur les ligands 2,2’-bis-pyridyl pontés, chélates à six chaînons, dont la synthèse est facile d’accès et les propriétés électroniques et structurales sont modulables<br>New cationic copper(I) complexes of general formula [Cu(NHC)(N^N)][X] and [Cu(P^P)(N^N)][PF6] were developed with 6-membered-ring 2,2’-bis-pyridyl derivatives as ligand. These complexes exhibited blue (420 nm) to green (520 nm) emissions in solid state, with large Stokes shifts and photoluminescence quantum yields up to 0.86. Furthermore, the emission of the [Cu(NHC)(N^N)][X] complexes via a thermally activated delayed fluorescence (TADF) was demonstrated. The first plastic scintillators incorporating copper(I) complexes and detecting gamma radiations were obtained with [Cu(P^P)(N^N)][PF6] complexes. Application of the [Cu(NHC)(N^N)][X] complexes to the LEC technology led to the first copper(I)-based blue emitting device. In the last chapter, we also demonstrated that copper(I) complexes [Cu(NHC)(N^N)][X] bearing a 2,2’-dipyridylamine as N^N ligand exhibited high cytotoxycity against different cancer cells lines. These complexes paved the way for the design of a new type of copper(I) anti-cancer agents with the opportunity to increase the selectivity against cancer cells via a vectorization of the N^N ligand. The versatility of these copper(I) complexes demonstrated in this work relied on the easy to handle and highly modular 2,2’-bis-pyridyl ligands
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Zakariya, Nasiru Imam. "Development of nuclear-radiological facility monitoring system." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2182.
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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.<br>The widespread application of nuclear science and technology has been the subject of much concern as well as nuclear safety issues. And to ensure the safety of public life, property and environment, it is indispensable to improve the emergency system for nuclear accidents and the environmental monitoring system for nuclear radiation, so that the occurrence of nuclear accidents, terrorist incidents and the resulting hazards can be prevented or minimized. Due to the benefits of radiation which were earlier and now recognized in the use of X-rays for medical diagnosis and then later with the discoveries of radiation and radioactivity, there was rush in exploiting the medical benefits which eventually led fairly to the recognition of the risks and induced harm associated with it. Thus, only the most obvious harms resulting from high doses of radiation, such as radiation burns, were initially observed and protection efforts were focused on their prevention, mainly for practitioners rather than patients. Subsequently, it was gradually recognized that there were other, less obvious, harmful radiation effects such as radiation-induced cancer, for which there is certain risk even at low doses of radiation.
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Aguwa, Kasarachi. "Radiation Dose Study in Nuclear Medicine Using GATE." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/593601.
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Dose as a result of radiation exposure is the notion generally used to disclose the imparted energy in a volume of tissue to a potential biological effect. The basic unit defined by the international system of units (SI system) is the radiation absorbed dose, which is expressed as the mean imparted energy in a mass element of the tissue known as "gray" (Gy) or J/kg. The procedure for ascertaining the absorbed dose is complicated since it involves the radiation transport of numerous types of charged particles and coupled photon interactions. The most precise method is to perform a full 3D Monte Carlo simulation of the radiation transport. There are various Monte Carlo toolkits that have tool compartments for dose calculations and measurements. The dose studies in this thesis were performed using the GEANT4 Application for Emission Tomography (GATE) software (Janet al., 2011) GATE simulation toolkit has been used extensively in the medical imaging community, due to the fact that it uses the full capabilities of GEANT4. It also utilizes an easy to-learn GATE macro language, which is more accessible than learning the GEANT4/C++ programming language. This work combines GATE with digital phantoms generated using the NCAT (NURBS-based cardiac-torso phantom) toolkit (Segars et al., 2004) to allow efficient and effective estimation of 3D radiation dose maps. The GATE simulation tool has developed into a beneficial tool for Monte Carlo simulations involving both radiotherapy and imaging experiments. This work will present an overview of absorbed dose of common radionuclides used in nuclear medicine and serve as a guide to a user who is setting up a GATE simulation for a PET and SPECT study.
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Houssay, Laurent P. "Robotics and radiation hardening in the nuclear industry." [Florida] : State University System of Florida, 2000. http://etd.fcla.edu/etd/uf/2000/ana6242/master.PDF.
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Thesis (M.S.)--University of Florida, 2000.<br>Title from first page of PDF file. Document formatted into pages; contains xii, 198 p.; also contains graphics. Vita. Includes bibliographical references (p. 186-197).
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Esparza, Enrique. "Radiation and litigation : analyses of the ALARA principle and low dose radiation in the courts, and the future of radiation in court cases." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41588.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.<br>Includes bibliographical references (leaves 36-39).<br>Currently there are a growing number of radiation workers. In order to ensure the safety of the employees, regulations have been established by the federal government and state governments to limit the dose equivalent to radiation workers. The most well known strategy for reducing radiation doses in the work place is the ALARA principle which stands for "as low as reasonably achievable". Within the phrase, "reasonably achievable" there is an implied element of subjectivity. Because "reasonably achievable" can vary in meaning for different people, this paper will analyze the ALARA principle in detail. Also, the manner in which inconclusive data on low dose radiation are treated in the court rooms will be evaluated. A secondary part of the paper will deal with what happens when accidents occur to radiation workers. Specifically, this paper will deal with the accidents at Kerr-McGee, Three Mile Island and SONGS. The thesis will delve into the litigation that followed the radiation accidents and analyses of the rulings, and will look at where current radiation litigation is heading.<br>by Enrique Esparza.<br>S.B.
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Barz, Ligia Liani. "Emissão de nucleons via mecanismo de Feshbach-Zabeck na colisão periférica de íons pesados relativísticos." Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-17042014-132754/.
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O mecanismo de \"troca de fônon\" de Feshbach e Zabek é revisto e uma discussão detalhada é fornecida sobre o papel das leis de conservação e relação \"tipo fônon\" entre energia e momento transferidos. São investigados os efeitos de correlações de curto alcance na emissão de nucleons em colisões periféricas de íons pesados relativísticos. A seção de choque é calculada na aproximação de Born usando uma adaptação conveniente do modelo de Karol para o estado inicial e ondas planas, explicitamente ortogonalizadas ao estado inicial, para estados finais. Comparações com os resultados obtidos por Bertulani et al. usando ondas planas puras para o estado final mostram que a ortogonalização desempenha um papel relevante no valor obtido para a seção de choque. Discute-se também a sensibilidade do resultado aos parâmetros usados na discussão do estado inicial.<br>Abstract The \"phonon exchange\" mechanism of Feshbach and Zabek is reviewed and the role of the conservation laws and of the \"phonon-like\" relation between energy and transfered momentum is discussed. The effects of short range correlations for the emission of pair in peripheral relativistic heavy ions collisions are investigated. The cross section is calculated in Born approximation using a suitable modification of Karol\'s model for the initial state and plane waves, explicitly ortogonalized to the initial state, for the final states. Comparisons with the results obtained by Bertulani et al. using pure plane waves for the final state show that the ortogonalization has a non-negligibe effect on the magnitude of the resulting cross-sections. Sensitivity to the parameters involved in the description of the initial state is also discussed.
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Fausto, Agnes Maria da Fonseca. "Propriedades termoluminescentes de Lif dopados com Cu e/ou Mg." Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-28042014-160529/.
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Foi pesquisado a termoluminescência (TL) do LiF dopado com diversas concentrações de Mg e/ou Cu. O efeito do tratamento técnico em cada ciclo (recozimento, irradiação com raios gama e leitura) foi estudado para cinco ciclos sucessivos. Três diferentes tratamentos técnicos foram pesquisados: 230°C- 10 min, 400°C -1h e 400°C-1h + 100°C-2h. Este último foi o tratamento utilizado em todas as amostras para o resto do trabalho, pois provocou o aparecimento de um único pico (IVG) na curva de emissão na temperatura de (242±4)°C, com sensibilidade razoável, para amostras dopadas com Mg ou Mg + Cu, expostas aos raios gama. As curvas de emissão de todas as amostras foram analisadas quanto à sensibilidade TL e temperatura de máximo dos picos, após uma exposição com 0,26 mC/kg de raios gama ou com 0,4 J/cm² de radiação ultravioleta ou ainda após as duas exposições anteriores consecutivamente. Para as exposições citadas, de um modo geral, o pico a (242±4°)C devido aos raios gama é bem mais alto que os picos a (102±3)°C e (168±4)°C resultantes da iluminação com os raios ultravioleta. Foi constatado que nessas amostras a radiação ultravioleta preenche as armadilhas diretamente, sem promover a fototransferência de portadores de carga de armadilhas profundas, preenchidas após exposição à radiação ionizante, para as mais rasas. Além disso os dois tipos de radiação preenchem preferencialmente armadilhas com profundidades diferentes. Esses fatos nos permitem propor o uso do LiF dopado com 0,1 ou 0,2 mol% de Mg com 0,03 mo/% de Cu entre as amostras estudadas para fins de dosimetria da radiação gama e ultravioleta simultaneamente. O efeito das impurezas de Mg e Cu na sensibilidade do LiF à radiação gama foi estudado, através de uma análise empírica, ajustando uma curva às alturas do pico IVG de todas as amostras. Dessa análise é possível concluir que se o LiF for dopado somente com Mg ele pode atingir uma grande sensibilidade à radiação ionizante sendo, porém, muito critica a concentração de Mg para a obtenção da sensibilidade máxima. Essa situação critica pode ser contornada com a adição de Cu que desempenha, de uma certa forma, o papel de desativador diminuindo a proporção dos Mg responsáveis pela TL.<br>Thermoluminescence (TL) of LiF doped with different concentrations of Mg and/or Cu has been investigated. The effect of the thermal treatment on the crystals in each cycle (annealing, gamma ray exposure and readout) was studied for five successive cycles. Tree different thermal treatments were examined: 230°C for 10 min, 400°C for 1h and 400°C for 1h followed by 100°C for 2h. LiF doped with Mg or Mg + Cu submitted to the last quoted thermal treatment and radiated with 137 Cs gamma rays showed a reasonable sensitivity and glow curve with only one peak (IVG) at (242±4)°C. From these data, this annealing was adopted for all samples. TL sensitivity and glow peak temperatures for all available samples exposed to 0,26mC/kg of gamma rays or 0,4 J/cm² of UV or to both radiations consecutively were also analysed. The glow peak due to gamma rays appears at (242±4)°C and is higher than the peaks at (I02±3)°C and (I68±4)°C due to UV light. It has been shown experimentally that UV radiation fills directly the traps, producing no phototransference of charge carriers from deep traps, filled by ionizing radiation, to the shallow ones. Furthemore, each radiation, gamma or UV, fills different depth traps preferentially. These characteristics show the potential usefulness of LiF:Mg,Cu in gamma and UV radiation dosimetry simultaneously. The best choise amongst all the analysed samples is LiF doped with 0,1 or 0,2 mol% of Mg and 0,03 mol% of Cu. Also the influence of dopants (Mg and Cu) on the TL sensitivity of LiF to gamma rays was investigated performing an empirical analysis. An excellent fit between the experimental data and a mathematical relation was obtained. From this study it was possible to conclude that if LiF has only Mg as impurity, its glow curve can exhibit a high sensitivity to ionizing radiation, being however the maximum sensitivity extremely dependent on the Mg concentration. This fact can be avoided adding small quantity of Cu, which behaves as a poisoner, decreasing the quantity of Mg responsible for TL signal.
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Hykes, Joshua Michael. "Verification and Validation of Radiation Transport Numerical Methods, Codes, and Nuclear Data for Estimating Radiation Dose to Patients." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-02172009-200421/.
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Computed tomography (CT) is an invaluable diagnostic tool in current medical practice. Unfortunately, the radiation dose imparted during a CT scan can be significant. This thesis seeks to develop, verify, and validate appropriate computational methods for computing this dose accurately and efficiently. The components of the model are the nuclear data, transport methods, and computer codes. Monte Carlo transport methods are employed primarily for their ability to accurately capture most of the relevant physical phenomena. Deterministic transport methods are subsequently verified and validated. The work is divided into three stages: experimental, verification, and validation. The experimental stage involves gathering high-fidelity data to aid in the validation procedures. Multiple radiation detection devices are employed to give greater certainty to the results. In addition, an important task is gathering data using a geometrically simplified phantom which is easier to model than the detailed Rando phantom. Towards this end, a CTDI FDA phantom is imaged. Exposure and dose measurements were taken in air and in the phantom center and periphery. The second stage, verification, involves the testing of the deterministic model for correctness of the methodology and the physics data, i.e. cross section library. Primarily, there are a few key assumptions which must be tested. The first is the importance of the secondary electron transport. Using Monte Carlo methods, it is found that the transport is unimportant for the accurate computation of the dose deposition distribution given the relatively low energy photons produced by x-rays tubes employed in CT scan machines. This makes the deterministic transport calculations much simpler. Next, the discretization of space, energy, and angle in the deterministic model is examined to ensure sufficient refinement capable of delivering accurate results. The Monte Carlo method is an excellent complement to deterministic methods, serving as reference as though it were an actual experiment, thus allowing the testing of these issues in a straightforward and highly controlled manner. In each discretization, the deterministic model proved capable, although some flux spectrum results differed by fifteen percent or more, mostly a result of the multigroup cross section set. Finally, after ensuring that the deterministic model was functioning as expected, a comparison was made of the simulations to the experimentally measured data. This was the most difficult of the tasks, in great part because of the lack of precise knowledge of detailed information concerning some of the parameters comprising the experimental setup. However, much effort was placed into conforming the simulations to the experiment as closely as possible. The ratio of exposures in the CTDI FDA phantom periphery-to-center is computed to within experimental uncertainty of about ten percent, while the absolute computed exposures have greater errors. The absolute exposures differed from the measured values by less than 35 percent.
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Khan, Niaz Ahmad. "Aspects of radiation curing." Thesis, City University London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241483.
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Hykes, Joshua Michael. "Radiation Source Mapping with Bayesian Inverse Methods." Thesis, North Carolina State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3538540.
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<p> We present a method to map the spectral and spatial distributions of radioactive sources using a small number of detectors. Locating and identifying radioactive materials is important for border monitoring, accounting for special nuclear material in processing facilities, and in clean-up operations. Most methods to analyze these problems make restrictive assumptions about the distribution of the source. In contrast, the source-mapping method presented here allows an arbitrary three-dimensional distribution in space and a flexible group and gamma peak distribution in energy. To apply the method, the system’s geometry and materials must be known. A probabilistic Bayesian approach is used to solve the resulting inverse problem (<p style="font-variant: small-caps">IP</p>) since the system of equations is ill-posed. The probabilistic approach also provides estimates of the confidence in the final source map prediction. A set of adjoint flux, discrete ordinates solutions, obtained in this work by the Denovo code, are required to efficiently compute detector responses from a candidate source distribution. These adjoint fluxes are then used to form the linear model to map the state space to the response space. The test for the method is simultaneously locating a set of <sup>137</sup>Cs and <sup>60</sup>Co gamma sources in an empty room. This test problem is solved using synthetic measurements generated by a Monte Carlo (<p style="font-variant: small-caps">MCNP</p>) model and using experimental measurements that we collected for this purpose. With the synthetic data, the predicted source distributions identified the locations of the sources to within tens of centimeters, in a room with an approximately four-by-four meter floor plan. Most of the predicted source intensities were within a factor of ten of their true value. The chi-square value of the predicted source was within a factor of five from the expected value based on the number of measurements employed. With a favorable uniform initial guess, the predicted source map was nearly identical to the true distribution, and the source intensities agreed within the predicted uncertainty. Using experimental data, the mapping was more difficult due to laboratory limitations. However, by supplanting 14 flawed measurements (out of 69 total) with synthetic data, the proof-of-principle source mapping was nearly as accurate as the synthetic-only prediction. </p>
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Labrecque, Rémi. "Relativistic hydrodynamics and electromagnetic radiation in relativistic nuclear collisions." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40818.
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Relativistic Hydrodynamics has successfully described the bulk of the data on soft hadrons at the Relativistic Heavy Ion Collider (RHIC), including the elliptic flow and the momentum spectra. In this work, we apply the hydrodynamic evolution model to the quark-gluon plasma (QGP) and hadronic phases created in relativistic heavy-ion collision at RHIC and at the Super Proton Synchrotron for different systems and energies. In these conditions, we calculate the spectra of dileptons and their elliptic flow.<br>Le model d'évolution hydrodynamique relativiste a décrit avec succès les propriétésd'ensemble des données sur les hadron "soft" produit au RHIC, incluant le flot elliptique. Dans ce travail, nous avons appliqué l'hydrodynamique relativiste aux phasesde plasma de quark et de gluons (PQG) et hadronique créées dans les collisions àhautes énergies aux Relativistic Heavy Ion Collider et Super Proton Synchrotron.Nous étudions le spectre et le flot elliptique des dileptons produits dans ces collisionsd'ions lourds.
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Strand, Aven Lynn. "Nuclear Radiation Awareness for Residents of Cascade County-Montana." Thesis, Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/strand/StrandA0806.pdf.
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The potential of a radiation mishap is real and lack of public awareness only potentiates the devastating outcomes on the citizens in the effected area should one occur. Low-level exposures of radiation may result in cancer and leukemia. A radiation mishap can occur at a missile site, a research or medical facility using radioactive material, a fixed nuclear facility, during nuclear detonation, and during transport of nuclear material. Guidance and education for limiting personal radiation exposure and how to combat radiation hazards would effectively reduce the number of individuals exposed if such a disaster were to occur. The intent of this project was to create an educational tool that would guide the residents of Cascade County in radiation awareness and ways to minimize radiation exposure to themselves and their families should a mishap occur. The outcome was the creation of a brochure for Cascade County's Disaster and Emergency Services department to use as an educational tool for the residents of Cascade County for radiation disaster preparedness. The brochure provides an organized, reader friendly outline of prevention of radiation exposure.
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Heywood, D. I. "Environmental radiation monitoring and the siting of nuclear facilities." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382436.
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Simonson, Scott A. "Modeling of radiation effects on nuclear waste package materials." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/36921.
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Adams, Mark Lloyd 1972. "Hydrogen radiation transport modeling in ALCATOR C-Mod." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85317.
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Nilsson, Oskar. "Radiation induced corrosion of steel." Thesis, KTH, Kärnkemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-40452.
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The aim of this thesis was to investigate the influence of aqueous radiation induced oxidants on stainless steel. This was done by exposing the steel to both radiation and chemically added oxidants under ambient conditions, i.e. in and near room temperature. When water is exposed to radiation several oxidizing species are formed, including hydrogen peroxide, which have been known to increase the risk for corrosion of other materials. Stainless steel is used in many parts in a nuclear power plant, and the results from this thesis could be useful when elucidating whether the steel is an appropriate material to use for these applications.
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Vestergren, Eleonor. "Administered radiopharmaceutical activity and radiation dosimetry in paediatric nuclear medicine." Lund : Dept. of Radiation Physics, University og Göteborg, 1998. http://catalog.hathitrust.org/api/volumes/oclc/39776733.html.
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Gunderson, Katie Marie. "Radiation damage in phosphates and silicates for nuclear waste disposal." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608095.
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Freeman, Helen Mary. "Characterisation of radiation damage in nuclear graphite at the nanoscale." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/13659/.
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Graphite is a key component in many of the UK's civil nuclear reactors whose lifetime is heavily dependent on the physical and chemical performance of the graphite. Exposure to neutron radiation at high temperatures (350C) induces complex structural changes over many length scales. This thesis focuses on the nanoscale, an area where a lack of understanding leaves a variety of contentious issues. Transmission electron microscopy (TEM), electron diffraction, and electron energy loss spectroscopy (EELS) were the three main experimental techniques used to study a range of virgin, electron irradiated, and neutron irradiated graphites. Information gained from energy filtered TEM, X-ray diffraction, and Raman was also used to compliment these techniques. In situ electron irradiation experiments were conducted at a range of temperatures to better understand the collective effect of thermal annealing and radiation damage. TEM lattice images were quantified using software provided by the PyroMaN research group to extract information about fringe length and tortuosity as a function of radiation damage. A 3D atomistic modelling technique was also applied to micrographs to produce 3D models of electron irradiated graphite. Electron irradiation resulted in the breaking and bending of basal planes and the fragmentation of crystallites. Analysis of electron diffraction patterns showed a 10% increase in d-spacing and polycrystallisation following electron irradiation. Low and core loss EEL spectra were collected during in situ electron irradiation which were fitted to extract information about specimen density, planar and non-planar sp2 content, and bond length. Irradiated specimens exhibited a reduced planar sp2 content which was thought to be attributed to the introduction of non-hexagonal rings and inter-planar defects. The reduction in planar sp2 bonded carbon was replaced by non-planar sp2 bonded carbon. Bond lengths were also seen to increase due to an increase in peripheral dangling bonds at crystallite boundaries. This quantitative analysis methodology was then applied to neutron irradiated specimens to analyse the bulk material and also material found within microcracks, the latter which could have a significant effect on irradiation-induced dimensional change.
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Raabe, Rebecca L. "Radiation effects on the blood-brain barrier." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/44779.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.<br>Includes bibliographical references (p. 53-56).<br>Selective vascular irradiation enables the critical examination of the vasculature and its role in the onset of late radiation effects. It is a novel approach to expose the endothelial cells to much higher levels of ionizing radiation relative to normal cells by utilizing the boron neutron capture reaction. When boron-containing compounds are restricted to the lumen of the blood vessel, the resulting high-LET alpha and lithium particles cannot deposit their energy in the normal cells beyond the vasculature after the target is exposed to thermal neutrons. This allows for a 2- to 3-fold increase in the calculated dose to the endothelial cells. However, this technique has been criticized because there is no direct evidence that the endothelial cells receive an absorbed dose from the selective vascular irradiation. The objective of this work is to provide corroborating experimental evidence that selective vascular irradiation physically damages the endothelial cells. An established assay utilizing blood-brain barrier disruption was adopted to quantify the radiation damage to the endothelial cells in female BALB/C mice, 8-12 weeks of age. A dye that attaches to the plasma proteins in the blood and that is ordinarily kept out of the brain by the blood-brain barrier is injected into the blood supply before the irradiation, and following irradiation, damage to the vasculature will result in disruption of the blood-brain barrier that allows blood stained with the dye to enter the brain. After sacrificing, the blood in the vessel lumen is cleared by performing a trans-cardiac perfusion, and the brain is homogenized and prepared for analysis. The absorbance of the resulting supernatant of each brain sample is measured with a spectrophotometer at the optimal wavelength of the dye.<br>(cont.) The absorbance is related to the quantity of blood that leaked through the blood-brain barrier, which is also related to the damage caused to the vasculature from exposure to ionizing radiation. Increased leakage through the blood-brain barrier was observed for those mice exposed to selective vascular irradiation, indicating a direct relationship between the leakage through the blood-brain barrier and the 10B concentration in the blood. The most significant increase in the leakage through the blood-brain barrier (p<0.002) was observed at the highest lOB concentration in the blood (161 ppm). The compound biological effectiveness (CBE) for sulfhydryl borane (BSH) was calculated to be 0.28, which is consistent with the published value of the CBE for BSH in the rat spinal cord. This suggests that the assumptions used for calculating the absorbed doses for selective vascular irradiation are reasonable and approximate to what the endothelial cells receive.<br>by Rebecca L. Raabe.<br>S.M.
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Reynolds, Adam Fisher. "Radiation modelling of vacuum field emission devices." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123359.
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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2019<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 76-78).<br>Recent advances in micro and nanofabrication techniques have enabled modern vacuum field emission devices (VacFEDs) and have been demonstrated in the laboratory for use as diodes and transistors. Modern VacFEDs operate through cold emission of electrons across a vacuum gap. It has been proposed that these devices are "radiation insensitive" since they do not have a solid state junction as in other modern electronic devices. Radiation testing has been conducted to characterize the radiation response for these devices however, minimal supporting modeling has been performed. This thesis attempts to model and quantify the radiation effects of modern VacFEDs.<br>It focuses primarily on two effects associated with ionizing radiation exposure to a VacFED diode materials and structure: 1) The production of a net electron Direct Drive (DD) current in conductive layers due to imbalance in ionization rates in device layers and 2) Radiation Induced Conductivity (RIC) due to creation and drift of electron-hole pairs across an electric field of a dielectric insulating layer. These currents are treated as a noise sources that compete with the output signal of the device. Two radiation transport codes are used quantify interaction, electron charge and energy deposition of consequence to direct drive and RIC effects: 1) CEPXS/ONEDANT: a 1-dimensional electron-photon discrete ordinates code package and 2) MCNP6: a general-purpose, continuous-energy, generalized-geometry, time dependent, Monte Carlo radiation-transport code. RIC response was found to have the greatest current for all device models considered over all energies.<br>This thesis found a dose rate of 6 x 106 rad(Si)/s at the surface of a VacFED diode is required to cause a 0.1 [mu] A noise current in a device designed to operate at 1.0 [mu]A. This finding suggests that VacFED technology has the capability to operate continuously in a modern pressurized water nuclear reactor core gamma ray environment, which has an approximate dose rate of 3 x 105 rad(Si)/s.<br>by Adam Fisher Reynolds.<br>S.M.<br>S.M. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering
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Yellen, Duncan Howard. "Radiation damage in hexagonal-close-packed metals." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316660.
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Chmill, Valery. "Radiation tests of semiconductor detectors." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4026.
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Nancekievill, Matthew. "The radiation tolerance and development of robotic platforms for nuclear decommissioning." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/the-radiation-tolerance-and-development-of-robotic-platforms-for-nuclear-decommissioning(75451a19-57c6-4809-92dd-9b683db9b10f).html.
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There is an increasing desire to deploy low-cost robotic systems in nuclear decommissioning environments. These environments include long-standing nuclear fuel storage ponds such as those at the Sellafield site in Cumbria, UK as well as areas affected by expulsion of radioactive material from sites such as the Fukushima accident in Japan 2011. An area of concern for the successful deployment of robotic platforms in a radioactive field is their radiation tolerance. It is necessary to understand how the low-cost components used within robotic platforms react to radiation exposure in a nuclear decommissioning environment. This thesis discusses the radiation tolerance of multiple commercial-off-the-shelf (COTS) components that are commonly used within a robotic platform up to an expected yearly total dose of 5 kGy(Si). It was found that COTS voltage regulators are susceptible to gamma exposure, however, development of a discrete voltage regulator showed an increased tolerance to radiation under certain load and temperature conditions. Inertial measurement units were also investigated and found to be susceptible to a total ionising dose.
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Ulmer, Bernd. "Back scatter imaging with megavoltage radiation." Thesis, University of Surrey, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246070.
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Saglam, Mehmet. "Alpha radiation effects on weapons grade plutonium encapsulating materials /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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