Cette thèse développe un système d'analyse en ligne compact, précis, rapide et autonome par spectrométrie de fluorescence X raies L, pour quantifier les transuraniens (uranium, plutonium et américium) présents dans les solutions et effluents des procédés du plutonium. Au cours de cette étude, la configuration, les paramètres de ce système et une méthode de quantification non destructive ont été définis puis la capacité du spectromètre à dissocier ces éléments dans de fortes concentrations relatives a été vérifiée. Des solutions contenant des éléments non radioactifs ont d'abord été étudiées afin de s'affranchir des effets dus à la désintégration des transuraniens et d'optimiser efficacement le spectromètre. Par simulations Monte-Carlo avec le code PENELOPE, une méthode de quantification a été mise au point et diverses configurations pour optimiser l'intensité d'excitation de l'échantillon et mesurer une raie de diffusion Compton de la source X ont été testées numériquement. Ces configurations ont été expérimentées avec un spectromètre prototype sur des solutions non radioactives pour valider et compléter la configuration la plus intéressante. Des solutions contenant des éléments en fortes concentrations relatives ont été analysées afin de déterminer une méthode de déconvolution des spectres avec le logiciel COLEGRAM et démontrer la faculté de cette méthode à quantifier de telles solutions. Quelques solutions d'uranium et de plutonium ont été analysées pour s'approcher au plus près des futures conditions expérimentales, caractériser et diminuer les effets dus à la désintégration des radioéléments. / This thesis deals with the development of a new compact, accurate, fast, without cooling liquid, fluorescence L X-ray spectrometer, with the aim to determinate online transuranic elements (uranium, plutonium and americium) in nuclear materials reprocessing. The objective was to define the configuration and the characteristics of this spectrometer and the method to quantify transuranic elements between 0.1 g/L and 20 g/L. To minimize as law as possible the manipulation of these elements, we have used an original approach, namely Monte-Carlo simulations and none radioactive surrogate elements. The study of these solutions allowed to eliminate the specific effects of transuranic elements decay (internal conversion) and to optimize the spectrometer. Monte-Carlo simulations with the PENELOPE code were used for two reasons. Firstly, we have developed an analytical method to correct the matrix effects. Then, we have selected three systems to produce a quasi-monochromatic X-rays beam from the X-ray generator, to optimize the intensity of the L X-ray fluorescence spectra, and to measure the Compton scatter peak. These systems were then tested with an adjustable spectrometer in order to select and optimize the best configuration. We have shown that, after peaks and left tails separation from spectra with COLEGRAM software, the spectrometer can be used to analyze solutions with various concentrations of thallium and bismuth. Several solutions of uranium or plutonium were analyzed to determine the effects of interferences from gamma rays and internal conversion with the fluorescence L X-rays. These effects have been corrected by subtracting a passive spectrum to an active one.

Text in Afrikaans with Abstracts in Afrikaans, English and isiZulu / In hierdie proefskrif word ondersoek ingestel na die parateks as narratiewe strategie vir toeganklikheid in geselekteerde Afrikaanse kinder- en jeugliteratuur. Die kern van hierdie ondersoek is die toeganklikheid van die boodskap binne die paratekstuele en narratiewe kommunikasiesituasie. Vir hierdie ondersoek is die sentrale probleemstelling soos volg geformuleer: hoe word die parateks as narratiewe strategie gebruik om kinder- en jeugliteratuur meer toeganklik vir jong lesers te maak? Gérard Genette se werk oor die parateks (1997a) en die narratologie (1983, 1990) dien as teoretiese basis vir hierdie studie se konseptuele raamwerk, aangevul deur die werk van Mieke Bal (1991, 2009). Jauss (1982) se resepsie-estetika word ook betrek ten einde toeganklikheid ten opsigte van die primêre teikenmark te formuleer. Binne die konteks van hierdie konseptuele raamwerk, word daar afsonderlik ondersoek ingestel na die ontvangers, senders en boodskap van die paratekstuele en narratiewe kommunikasiesituasie. Die ontvangers is die lesers van die parateks as narratiewe strategie vir toeganklikheid en word bespreek as die primêre, dubbele en tweeledige teikenmarkte. Die senders is die verskillende skrywers betrokke by die skepping en implementering van die parateks as narratiewe strategie vir toeganklikheid. Onderskeid word getref tussen die primêre skrywer, die tweede skrywer en die sekondêre skrywer. Laastens word die boodskap ondersoek soos dit met die visuele parateks en die talige parateks verband hou. Aan die hand van die konseptuele raamwerk van hierdie studie, en die verskillende rolspelers en boodskappe binne die paratekstuele en narratiewe kommunikasiesituasie, dui die studie aan hoe die parateks as narratiewe strategie gebruik kan word om kinder- en jeugliteratuur vir veral die primêre teikenmark meer toeganklik te maak. / This thesis sets out to illustrate how the paratext can be used as narrative strategy for accessibility in selected Afrikaans children’s and youth fiction. Central to this study is the accessibility of the message in the paratextual and narrative communication situation. In this regard, the central research question is as follows: how can the paratext be used as a narrative strategy to make children’s and youth literature more accessible for young readers? Gérard Genette’s work on the paratext (1997a) and narratology (1983, 1990) serves as the theoretical basis for this study’s conceptual framework, along with the work of Mieke Bal (1991, 2009). In order to define accessibility in terms of the primary target audience, reference is also made to Jauss’s (1982) reception theory. Within the context of this conceptual framework, focus is placed on the receivers, senders and message of the paratextual and narrative communication situation. The receivers are the readers of the paratext as narrative strategy for accessibility and are discussed as the primary, twofold and dual target audiences. The senders are the different writers involved in the creation and implementation of the paratext as narrative strategy for accessibility. Here a distinction is made between the primary writer, the second writer and the secondary writer. Lastly, the message is discussed as it relates to the visual paratext and textual paratext. Through the conceptual framework of this study, along with the different role players and messages of the paratext as narrative strategy for accessibility, this study shows how the paratext as narrative strategy can be used to make children’s and youth literature more accessible for especially the primary target audience. / Le thisisi ihlose ukuveza ukuthi umbhalo ohunyushiwe ungasetshenziswa kanjani njengesu lokuxoxa emibhalweni ekhethiwe yesiBhunu yezingane kanye naleyo yabantu abasha .Okubalulekile kulesi sifundo socwaningo wukutholakala komlayezo wombhalo ohunyushiwe kanye nesimo sokuxhumana ngengxoxo. Ngalokho-ke, umbuzo oyinsika kulesi sifundo socwaningo ngolandelayo: Ngabe inkulumo ehunyushiwe ingasetshenziswa kanjani njengesu lokuxoxa, elingenza ukuthi imibhalo yobuciko yezingane kanye naleyo yabantu abasha ukuze itholakale kalula kubafundi abasebasha? Umsebenzi kaGérard Genette i-paratext (1997a) kanye ne-narratology (1983, 1990) usebenza njengesisekelo sesakhiwo sebizo salesi sifundo socwaningo, kanti lokhu kuhambisana nomsebenzi ka MiekeBal (1991,2009). Ukuze siphumelele ukuchaza mayelana nokutholakala kwabafundi bezincwadi abahlosiwe, uyanxuswa ukuthi ufunde ithiyori emayelana nokutholakala kwabafundi bomlayezo ka Jauss (1982). Ngaphansi kwesimo sesakhiwo segama, kugxilwe kakhulu kubamukeli, kubathumeli kanye nakumlayezo wombhalo ohunyushiwe kanye nesimo sokuxhumana ngengxoxo. Abamukeli bomlayezo kungabafundi bombhalo ohunyushiwe, okuyisu elisetshenziswa ukuthola umlayezo, kanti la masu axoxwa njengalawo aqonde abafundi bokuqala, abambaxambili futhi anezinhloso ezimbili.. Abathumeli bomlayezo kungabhali abadlala indima yokwakha kanye nokusebenzisa imibhalo ehunyushiwe njengesu lokuxoxa elisetshenziswa ukuthola umlayezo. Lapha, kuvezwa umehluko ophakathi kombhali wokuqala, umbhali wesibili kanye nombhali osezingeni lesibili. Okukugcina, umlayezo uxoxwa njengoba uhlobana nombhalo ohunyushiwe obukelwayo kanye nombhalo ohunyushiwe olotshiwe Ngokusebenzisa uhlelo lwesakhiwo segama salesi sifundo, esisebenzisana ndawonye nabadlali bendima abahlukahlukene kanye nemilayezo yombhalo ohunyushiwe njengesu lokuxoxa elisetshenziswa ukuthola umlayezo, lokhu kukhombisa ukuthi umbhalo ohunyushiwe oyisu lokuxoxa ungasetshenziswa kanjani ukwenza ukuthi imibhalo yobuciko yezingane kanye naleyo yabantu abasha ingatholakala kanjani, ikakhulukazi ngabafundi bokuqala abahlosiwe. / Afrikaans and Theory of Literature / D. Litt et Phil. (Afrikaans)