23000 tonnes de déchets graphites seront générés lors du démantèlement de la première filière de réacteurs en France (9 réacteurs Uranium Naturel Graphite Gas, UNGG). Ces déchets radioactifs sont classés dans la catégorie Faible Activité Vie Longue (FAVL). Dans le cadre de la loi, l'agence nationale pour la gestion des déchets radioactifs (Andra) étudie un concept de stockage à faible profondeur. Cette étude s'intéresse plus particulièrement au carbone 14, qui est un des principaux radionucléides à vie longue (5730 ans) dans les déchets graphite, mais aussi au tritium qui est l'un des principaux contributeurs de la radioactivité à court terme. Ces deux radionucléides ont la particularité d'exister sous différentes formes, aussi bien en phase gaz (14CO2, HT,...) qu'en phase liquide (14CO32-, HTO,...). Leur spéciation va influencer leur migration du stockage vers l'environnement. Des expériences de lixiviation en milieu alcalin (NaOH 0,1mol.L-1, simulant les conditions de stockage), ont été réalisées sur des échantillons de graphites irradiés provenant de deux réacteurs : SLA2 et G2, afin de quantifier leur relâchement et de définir leur spéciation. Les études montrent que le carbone se trouve aussi bien en phase gaz qu'en phase liquide. Dans la phase gaz, le relâchement est faible (< 0,1%), et correspond à des formes oxydables. Le carbone 14 est relâché majoritairement en phase liquide : 65% de la fraction d'inventaire relâchée est sous forme de carbone 14 inorganique, et 35% de carbone 14 organique. Deux formes de tritium ont été identifiées dans la phase gaz : HTO et HT/Tritium Organiquement Lié. Plus de 90% du tritium en phase gaz se trouve sous forme HT/TOL, mais ce relâchement est faible (<0,1%). Majoritairement le tritium est en phase liquide sous forme HTO.

Disertacijos tyrimo objektu buvo Pietryčių Lietuvos kvartero komplekso daugiasluoksnės uolienų storymės požeminio vandens ištekliai (balansas, pasiskirstymas ir formavimas). Disertacinio darbo metu pagrįsti ir suformuluoti kvartero daugiasluoksnės uolienų storymės schematizavimo principai – patikslinta hidrogeodinaminės sistemos sandara remiantis litologiniais duomenimis ir vandeningų sluoksnių tarpusavio ryšio sąlygomis, naudojant hidrogeocheminius, izotopinius ir hidraulinius tyrimus. Išskirti vandeningieji ir pusiau laidūs sluoksniai bei sudarytas kvartero vandeningojo komplekso matematinis modelis. Atlikta ekspertinė modeliavimui naudotų hidrogeologinių parametrų analizė – jų patikimumas tikslintas kalibruojant modelį hidrogeologiniais, infiltracinės mitybos, požeminio nuotėkio balansiniais paskaičiavimais bei požeminio vandens cheminės sudėties ir izotopiniais tyrimais. Parinktame eksperimentiniame hidrogeologiniame pjūvyje – vandens filtracijos kelyje įvertinta požeminio vandens cheminės-izotopinės sudėties transformacija. Remiantis tričio tyrimo ir matematinio modelio duomenimis regioniniame pjūvyje atlikta filtracijos schemos bei filtracijos greičių korekcija. Pirmą kartą, naudojant matematinio modeliavimo metodus, įvertintos Pietryčių Lietuvos kvartero vandeningojo komplekso gamtinių ir eksploatacinių prognozinių gėlo požeminio vandens išteklių formavimosi sąlygos, nustatytas galimas požeminio vandens gavybos poveikis aplinkai. / The aim of the research was accomplish an assessment of the groundwater resources (budget, distribution and formation) and reveal their formation peculiarities in the Quaternary aquifer system of the southeaster part of Lithuania. Substantiation and formulation of schematization principles of the Quaternary multi-aquifer system for conceptualization of groundwater flow model based on the complex of lithologic, hydrogeochemistry, isotopic and hydraulic data have been developed by this dissertation. Performing data analysis of hydraulically tested aquifers, the hydrogeological parameters which have been used in simulation and their reliability have been adjusted during model calibration based on hydrogeological–hydrological water balance methods with coupled groundwater isotopic-chemistry investigations. Transformation of groundwater isotope-hydrogeochemical composition in the direction from the recharge area toward the discharge places have been estimated on a selected experimental hydrogeological cross–section. According to tritium and simulation modelling data, groundwater flow scheme and average velocity comparison have been made from the highland to lowland. The pre–development groundwater flow and prognostic assessment of groundwater exploitation resources of Quaternary aquifer system with extraction impact on the geoenvironment have been evaluated.

The aim of the research was accomplish an assessment of the groundwater resources (budget, distribution and formation) and reveal their formation peculiarities in the Quaternary aquifer system of the southeaster part of Lithuania. Substantiation and formulation of schematization principles of the Quaternary multi-aquifer system for conceptualization of groundwater flow model based on the complex of lithologic, hydrogeochemistry, isotopic and hydraulic data have been developed by this dissertation. Performing data analysis of hydraulically tested aquifers, the hydrogeological parameters which have been used in simulation and their reliability have been adjusted during model calibration based on hydrogeological–hydrological water balance methods with coupled groundwater isotopic-chemistry investigations. Transformation of groundwater isotope-hydrogeochemical composition in the direction from the recharge area toward the discharge places have been estimated on a selected experimental hydrogeological cross–section. According to tritium and simulation modelling data, groundwater flow scheme and average velocity comparison have been made from the highland to lowland. The pre–development groundwater flow and prognostic assessment of groundwater exploitation resources of Quaternary aquifer system with extraction impact on the geoenvironment have been evaluated. / Disertacijos tyrimo objektu buvo Pietryčių Lietuvos kvartero komplekso daugiasluoksnės uolienų storymės požeminio vandens ištekliai (balansas, pasiskirstymas ir formavimas). Disertacinio darbo metu pagrįsti ir suformuluoti kvartero daugiasluoksnės uolienų storymės schematizavimo principai – patikslinta hidrogeodinaminės sistemos sandara remiantis litologiniais duomenimis ir vandeningų sluoksnių tarpusavio ryšio sąlygomis, naudojant hidrogeocheminius, izotopinius ir hidraulinius tyrimus. Išskirti vandeningieji ir pusiau laidūs sluoksniai bei sudarytas kvartero vandeningojo komplekso matematinis modelis. Atlikta ekspertinė modeliavimui naudotų hidrogeologinių parametrų analizė – jų patikimumas tikslintas kalibruojant modelį hidrogeologiniais, infiltracinės mitybos, požeminio nuotėkio balansiniais paskaičiavimais bei požeminio vandens cheminės sudėties ir izotopiniais tyrimais. Parinktame eksperimentiniame hidrogeologiniame pjūvyje – vandens filtracijos kelyje įvertinta požeminio vandens cheminės-izotopinės sudėties transformacija. Remiantis tričio tyrimo ir matematinio modelio duomenimis regioniniame pjūvyje atlikta filtracijos schemos bei filtracijos greičių korekcija. Pirmą kartą, naudojant matematinio modeliavimo metodus, įvertintos Pietryčių Lietuvos kvartero vandeningojo komplekso gamtinių ir eksploatacinių prognozinių gėlo požeminio vandens išteklių formavimosi sąlygos, nustatytas galimas požeminio vandens gavybos poveikis aplinkai.

Various fuel cycles for a sodium-cooled, subcritical, fast reactor with a fusion neutron source for the transmutation of light water reactor spent fuel have been analyzed. All fuel cycles were 4-batch, and all but one were constrained by a total fuel residence time consistent with a 200 dpa clad and structure materials damage limit. The objective of this study was to achieve greater than 90% burn up of the transuranics from the spent fuel.

Honey Lake Basin is a large, hydrologically closed valley with two playa lakes that are separated by a low elevation sill. The Basin has a complex hydrogeologic setting, with numerous groundwater flow paths that interact with surface waters and three basic aquifers; shallow, deep, and geothermal. Thirteen flow paths; eleven cold and two thermal, are identified and the geochemical evolution of those paths are characterized by integrating solute chemistry and isotopic data. The chemical flow paths include recharge in either granitoid or volcanic terrains in the Sierra Nevada Range and the Modoc Plateau, respectively. The groundwater then flows through alluvial fan and stream sedimentary environments and eventually flows through lacustrine and playa sediments in the closed basin. This investigating characterizes geochemical evolution of groundwater flow from both mafic and granitic terrains to lacustrine sediments with evaporite minerals, in a closed basin environment. Temperature data reveal that thermal waters circulate to 1.6-3.0 km and 2.8-3.8 km along two major fault zones. Shallow groundwaters above 17°C are determined to have a component of thermal water and mixing ratios are presented. δ18O and δD data show that deep groundwater was recharged by cooler, more humid precipitation from the last ice age, whereas shallow groundwaters reflect current meteoric conditions and show extensive evaporation trends. The two thermal flow paths show exchange with silicate minerals at high temperatures (>100°C). δ13C data show interaction with carbonate minerals in basin fill lacustrine sediments. 3H concentrations and 14C ages show that deep groundwaters throughout the Basin and shallower groundwaters in the center of the basin are not greatly affected by post-1952 recharge. Mean 14C ages range from modern to 23,500 years old. NETPATH was used to model geochemical evolution along the flow paths. Groundwater on the west side of the basin (granitic terrain) is typically low TDS (~150 mg/L) calcium-bicarbonate water and evolves into higher TDS (~300 mg/L) sodium-bicarbonate groundwater as it interacts with granitic rocks and then lacustrine sediments. Groundwater on the east side of the basin (mafic terrain) is typically low TDS (~200 mg/L) sodium-bicarbonate water and evolves into high TDS (~300 mg/L) sodium-bicarbonate water groundwater as it interacts with mafic rocks and then lacustrine sediments. Dissolution of silicate minerals and calcite, and ion exchange with clays is responsible for major chemistry changes. As both of these types of groundwaters come into contact with lacustrine sediments with evaporite minerals on the playas, dissolution of halite and gypsum dominate and the groundwater becomes extremely high in TDS (~ 1100 mg/L on the Honey Lake Playa and ~ 43,000 mg/L on the Fish Spring Playa) and strongly sodium-chloride in character.

A geochemical study of major springs and wells in Spring Valley, Nevada, and Snake Valley, Utah-Nevada was initiated in response to the Clark, Lincoln and White Pine Counties Groundwater Development Project proposed by the South Nevada Water Authority (SNWA). Water budget estimates suggest that interbasin flow accounts for a significant portion (~25%) of the water budgets in Spring and Snake Valleys. Although interbasin flow is possible in some areas, alternative plausible explanations place significant uncertainty on water budget allocations. To examine the plausibility of local and interbasin flow paths the groundwater flow in Spring and Snake Valleys was evaluated using solute and isotopic data. Evidence for local flow paths includes: 1) stable isotope values in local areas which are similar to isotope values in adjacent recharge zones; 2) measurable 3H content and 14C activities ≥ 50 pmc in most samples which suggests short residence times; and 3) plausible geochemical models of local flow paths. Previously defined interbasin flow paths in southern Spring Valley are marked by samples that have low 14C activities (mean = 20.14 pmc), which are consistent with long residence times and can be explained by either interbasin flow from adjacent basins or deep circulation in the basin-fill sediments of Spring Valley. Interbasin flow from southern Spring Valley to southern Snake Valley cannot be confirmed or rejected based on the current data and modeling constraints, which result in plausible models involving both local flow paths and interbasin flow paths. Interbasin flow from northern Spring Valley to northern Snake Valley is unlikely and can be explained by the deep circulation of groundwater that is mixed with modern recharge. The plausibility of alternative explanations to describe previously defined interbasin flow paths suggests that water budget allocations in Spring and Snake Valleys should be redistributed or reevaluated. The use of existing water budgets that allocate large components of water to interbasin flow to determine the distribution of water resources may result in incorrect estimations of available resources.

This study examines the efficiency of ion cyclotronresonance heating in multi-ion plasmas in JET (Joint EuropeanTorus), using deuterium and tritium as fuel along with smallconcentrations of a third ion species. In particular, two ionminority scenarios, hydrogen and helium, as well as a 3-ionscenario using beryllium were constructed. The scenarios weresimulated with FEMIC and the obtained data was then compiledand analyzed through a number of metrics.The highest total power absorption was 8.56 W and wasachieved by the 4% hydrogen scenario. However, 8% hydrogenattained the highest power partition by the minority ion species.The optimal beryllium concentration regarding absorbed powerwas 0.1% in 36.2% deuterium and 63.4% tritium, with a totalcoupled power of 6.94 W. The highest power partition byberyllium was noted for the 0.25% case in a 36% deuteriumand 63% tritium plasma. / Denna studie undersöker effektiviteten av joncyklotronresonansuppvärmning av JETs (Joint European Torus) plasma, med deuterium och tritium som bränsle, samt små koncentrationer av ett tredje ämne. Mer specifikt undersöks två scenarier med minoritetsjoner, helium och väte, och ett 3-jonscenario med beryllium. För att undersöka dessa olika konstellationer körs simuleringar i FEMIC. Datan som fås från simuleringarna sammanställs och analyseras i enlighet med olika mått. Den högsta totala absorptionen av energi var 8.56 W och fas av 4% väteminoritet. 8% väte ger den högsta energipartitionen för det tredje jonslaget. Beryllium absorberade som mest 6.94 W, detta med 0.1% beryllium, 36.2% deuterium och 63.4% tritium. Den högsta energipartitionen för beryllium uppnåddes med 0.25% beryllium, 36% deuterium och 63% tritium. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

Le but des recherches entreprises est l'étude des mélanges réels ou potentiels des eaux souterraines dans différents types de terrains. Pour ce faire, nous avons choisi plusieurs exemples de milieux poreux soit: des alluvions post glaciaires, des niveaux calcaires fissures, des marno-calcaires faiblement fissurés, du socle granitique fissuré et altéré. Les analyses des teneurs en tritium dans ces eaux, prélevées en des points représentatifs, constituent le moyen d'investigation principal en vue de définir les différents aspects des circulations souterraines. La teneur en tritium des eaux étudiées est déterminée par scintillation liquide après enrichissement. Les mesures ont été faites au Laboratoire du tritium du S.A.A.R. du C.E.N. de Grenoble ;

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A APA Sul RMBH, Área de Proteção Ambiental Sul da Região Metropolitana de Belo Horizonte, localizada na porção noroeste de uma das maiores regiões produtoras de minérios, o Quadrilátero Ferrífero, é conhecida pela riqueza de sua biodiversidade, seus aspectos sócioculturais e econômicos e, principalmente, pelo seu grande potencial mineral. Nela ocorre a Formação Cauê, formação geológica conhecida pela ocorrência de minérios ferrosos e também por abrigar grandes volumes de água no subsolo. Essa unidade hidrogeológica, conhecida como Aquífero Cauê, é o objeto de estudo desse trabalho. A área delimitada para este estudo encontra-se quase completamente inserida da APA Sul e está localizada na porção noroeste do Quadrilátero. Foram realizadas medidas em quarenta e sete amostras água, entre nascentes, cabeceiras de drenagem, drenos e poços. Foram amostrados pontos de surgência dos Aquíferos Inconsolidados, Gandarela, Quartizítico, Unidades Confinantes, mas principalmente o Aquífero Cauê, no período de estiagem das chuvas em 2011. Estas amostras tiveram seu conteúdo de deutério, oxigênio-18 e trítio determinados. Destas, vinte e três também tiveram suas características químicas investigadas. Águas de chuva foram coletadas durante um ano em três pontos na área de estudos. O conteúdo de trítio e razões isotópicas de deutério e oxigênio-18 foram determinados para amostras mensais de precipitação. Os resultados possibilitaram a determinação da Linha Meteórica Local, além da atividade atual de trítio nas precipitações que subsidiou o cálculo de tempo de renovação das amostras água subterrânea. A Linha Meteórica obtida evidenciou desvio da Linha Meteórica Global quanto ao excesso de deutério. Os Efeitos Quantidade e Temperatura puderam ser observados na região. A baixa mineralização das águas do Cauê, evidenciada pelos baixos valores de condutividade elétrica, dificultou a classificação das águas, e um padrão químico não pode ser observado. Os resultados de 18O e 2H indicaram rápida infiltração para a maioria das amostras, com exceção de um grupo cuja maioria é composta por águas relacionadas aos aquíferos de cobertura. O tempo de renovação das águas subterrâneas foi calculado pelos Modelos de Fluxo em Pistão e Exponencial. Os resultados apresentaram grande variação, entre 1,5 e 279 anos. / The Environmental Protection Area of the South Metropolitan Region of Belo Horizonte City, known as APA Sul RMBH, located on the northwestern portion of one of the largest oreproducing regions, named Quadrilátero Ferrífero (Iron Quadrangle), is known for the richness of its biodiversity, its socio-cultural and economic and especially to its great mineral potential. In this area, occurs the Cauê Formation, a geological formation recognized for the high occurrence of iron ores and also host large volumes of fresh water in the underground. This hydrogeologic unit, known as Cauê Aquifer, is the object of study of this work. The area defined for this study is almost completely inserted into the cited protection are and is located in the northwestern portion of the Quadrangle. Measurements were taken in forty-seven water samples, including springs, headwater drainage, drains and wells. Sampled were taken of unconsolidated aquifers, Gandarela, Quartizitic, confining units, but mainly Cauê Aquifer, during the dry season rainfall in 2011. These samples had the content of deuterium, oxygen- 18 and tritium determined. Of those, twenty-three were also investigated about its chemical characteristics. Rainwater was collected during one year at three stations located the study area. The content of tritium and deuterium isotope ratios and oxygen-18 were determined on monthly samples of precipitation. The results allowed the determination of the Local Meteoric Water Line, beyond the current activity of tritium in precipitation that supported the calculation of groundwaters residence time. The Local Meteoric Line obtained showed considerable deviation from the Global Meteoric Line on the excess of deuterium, while the slope was similar to the global one. The quantity and temperature effects were observed. The low mineralization of the groundwaters, evidenced by low values of electrical conductivity has obstructed their classification. A chemical pattern could not be attributed to the aquifer. The 18O and 2H results indicate rapid infiltration for most samples, except for a group formed mainly by water related to unconsolidated aquifers. The residence time of groundwater samples was calculated by piston flow and exponential flow models. The results showed a great variation, with waters between 1.5 and 279 years old.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-02-03T11:46:20Z No. of bitstreams: 0 / Made available in DSpace on 2016-02-03T11:46:20Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP