D.Phil. / The existence of radioactive waste (or ‘radwaste’) has become a problem that afflicts the nuclear industry worldwide. The search for a social consensus on radwaste management strategies is proving to be one of the most complex challenges facing nuclear technological development. The categories of radwastes that are currently of greatest concern are spent nuclear fuel (SF) that is discharged from nuclear power reactors and high level waste (HLW) arising from reprocessing of SF, as they continue to accumulate in storage facilities around the world and perceived to be without an end solution to their existence. Like many other nuclear countries, South Africa too is facing major decisions about future management of SF that is generated from its nuclear power and research reactors. It remains undecided on which of the available spent fuel management (SFM) options it must adopt. This research study seeks to produce a framework for evaluating SFM options that will identify and characterise the elements or aspects to be analysed, and use it to evaluate the SFM options in order to identify a preferred or optimum option for South Africa. The methodological approach to this study involves the use of literature research, a case study on Eskom’s SFM approach and a questionnairebased survey complemented by in-depth interviews with key stakeholders of nuclear power in South Africa. These qualitative methods are used to verify and validate the SFM evaluation framework. To complement the qualitative approach, a cost analysis of the options based on input from Eskom and literature data as well as on assumed scenarios, is carried out. Both the qualitative and the cost analysis lead to identification of a preferred SFM option for South Africa. Three principal SFM options were identified and evaluated: the reprocessing and recycling (or closed fuel cycle) option, the direct disposal (or once-through fuel cycle) option, and the indefinite storage (or deferral-of-a-decision) option. There are at least nine categories of issues that have been identified as factors affecting these SFM options: technology, safety, environmental impact, proliferation resistance, physical security, economics, sociopolitical influence, ethical principles and institutional capability. These formed the evaluation framework and were used as the criteria for the assessment of the SFM options. Based on the analysis conducted in the study concerning the feasibility of the SFM options for the South African context in terms of these criteria, it is concluded that the direct disposal option is the most favourable option for implementation in the South African nuclear power programme. However, all three options have their technical merits but are also contentious in various degrees both within the nuclear industry and the public domain.

D.Sc. / The ion exchange properties of a number of synthetic inorganic ion exchangers and the natural zeolite, clinoptilolite, were evaluated with respect to the elements Na, Cs, Sr, Ba, Ce(III), Eu, Zr, U(VI), Np(V), PU(IV) and Am(III). The role of the structure of crystalline exchangers in determining the selectivity thereof, especially in the case of clinoptilolite, was also investigated. Hydrated antimony pentoxide and antimonic acid showed high sorption of a number of ions over a wide pH range (2 - 10). The selectivity order of hydrous oxides for the actinides was as follows: PU(IV) > Am(III) > U(VI) > Np(V). Titanium phosphate, zirconium phosphosilicate and sodium titanate, however, preferred U to Am. To predict the selectivity order of crystalline inorganic ion exchangers, the Eisenman theory could be used, but other factors such as ion sieve effects had to be taken into account. In such cases the parameters contributing to the change in free energy during ion exchange plays a major role. Samples containing clinootilolite from two deposits in South Africa were evaluated with respect to chemical composition, conversion to the sodium, calcium and cesium forms, as well as the sorption of Cs and Sr from various media. Similar trends to those:reported for clinoptilolite from other parts of the world were found. Rietveld refinement of the structure of Cs-exchanged clinoptilolite was carried out using powder diffraction data and the computer program WYRIET. The zeolite was not isolated from the natural matrix, which meant that a number of phases had to be included in the refinement process. The refinement confirmed the...

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Neste trabalho é apresentado o potencial de remoção de íons estrôncio de soluções aquosas pelas fibras de coco na forma bruta e na forma ativada com peróxido de hidrogênio, 1% e 4%, em meio básico. Os experimentos de biossorção foram realizados em batelada com 2 mg.L-1 de solução de Sr(NO3)2 e foram estudadas as influências dos seguintes parâmetros: tempo de contato, pH e a eficiência de biossorção das fibras ativadas em comparação com a fibra de coco bruta (FCB). A caracterização das fibras antes e após o tratamento, e a presença de Sr2+ nas fibras foram realizadas por microscopia de varredura eletrônica com detector de espectroscopia de energia dispersiva, espectroscopia de difração de raios X, espectroscopia de infravermelho e por análise térmica. Dentre as fibras estudadas, a fibra de coco ativada com 1% H2O2 (FCA 1) apresentou a maior capacidade de biossorção: 3,6 mg.g-1, nas seguintes condições: 5 mg de biomassa em pH 6, após 90 minutos de tempo de contato à temperatura ambiente. A fibra de coco ativada com 4% H2O2 (FCA 2) levou a uma maior degradação dos constituintes da fibra e consequentemente a uma menor remoção de íons de Sr2+.Para os estudos de modelos de isotermas de biossorção de Sr2+, tanto a FCB quanto a FCA 1 ajustaram-se melhor ao modelo de Langmuir e à cinética de pseudo-segunda ordem. Os parâmetros termodinâmicos energia livre de Gibbs (ΔG) e coeficiente de distribuição (KD) foram -0,90 kJ.mol-1 e 265,3L.Kg-1 para a FCB e de -7,2 kJ.mol-1 e 824,3 L.Kg-1 para a FCA1. Esses resultados demonstraram que a FCA 1 possui uma boa eficiência para remover íons de Sr2+de resíduos químicos aquosos e é uma boa alternativa no tratamento de rejeitos radioativos líquidos contendo íons 90Sr. / This work presents the potential of strontium ions removal from aqueous solutions using coconut fiber in raw and treated form with hydrogen peroxide, 1% and 4%, in alkaline conditions. The biosorption experiments were performed in batch mode with 2 mg.L-1 solution of Sr(NO3)2 and the influence of the following parameters were studied: contact time and pH. It was also evaluate the biosorption efficiency of the treated coconut fibers in comparison with the raw coconut fiber (RCF). The fibers characterizations before and after treatment and the presence of the Sr2+ in the fibers were performed by scanning electron microscopy with a detector energy dispersive spectroscopy, diffraction of x-ray spectroscopy, infrared spectroscopy and thermal analysis. Among the studied fibers, the treated coconut fiber with 1% of H2O2 (TCF 1) showed the major biosorption capacity of 3.6 mg.g-1 in the following conditions: 5 mg of biomass at pH 6, 90 minutes of contact time at room temperature. Treated coconut fiber with 4% H2O2 (TCF 2) showed the lowest Sr2+ ions removal due to degradation of the fibers constituents. For studies of biosorption isotherms, both raw and treated coconut fiber (TCF 1) were fitted better to Langmuir model and the kinetics reaction was of pseudo-second order. The thermodynamic parameters Gibbs free energy (ΔG) and distribution coefficient (KD) were -0.90 kJ.mol-1 and 265.3 L.Kg-1 for RCF and of -7,2 kJ.mol-1 and 824.3L.Kg-1 for TCF 1. These results demonstrated that the TCF 1 has good efficiency for removing Sr2+ ions in the aqueous chemical waste and is a good alternative in treatment of liquid radioactive wastes containing 90Sr.

This work investigates the factors which might influence public opinion regarding the nuclear power industry, and the accuracy of existing theories about that opinion. West Cumbrian opinion is of particular interest, because the area has the highest concentration of the nuclear power industry in the UK, and might thereby represent a potentially 'nuclear-friendly' area which would contrast with the increasing scepticism reported in the rest of the country, and indeed across much of the industrialised world. The factors which may influence public opinion are analyzed in three ways. Firstly, historical factors are presented in an account of the development of the nuclear power industry. Next, the socio-economic situation and traditions of West Cumbria are examined, in order to assess particular local influences on public opinion. Thirdly, the public relations methods of important local and national groups are examined in the light of public relations theories, in order to assess the ability of such groups to influence public opinion (a new avenue of research related to nuclear power). In order to discover the state of West Cumbrian opinion in 1994, and to assess the impact of the above factors upon that opinion, a survey was conducted using a representative sample of the population of Cockermouth, chosen as a typical Cumbrian town. The scope of questions employed in previous studies was broadened to analyze attitudes towards antinuclear groups as well as towards the industry. Great attention was paid to the methodology of the new survey, the findings of which were analyzed in the light of a comparative analysis of existing research and theories related to West Cumbrian opinion. Local opinion was contrasted with that of a national 'public' consisting of political, environmental and energy orientated organizations. This study confirmed some previously held ideas about public opinion, but also found several differences which suggest flaws in the methodology of previous research. One very important finding was that it is important not to overstate the existence of controversy surrounding the nuclear industry in West Cumbria. Overall, the West Cumbrian population appeared to be relatively nuclear friendly, but not as strongly pro-nuclear as might have been thought. A surprisingly large number of people displayed a lack of knowledge about the subject, and many showed feelings of apathy and alienation. Nuclear power and coal were found to be controversial choices of fuel supply. Wind power received more support and less opposition. Environmental groups were seen to perform a watchdog role, for which they were welcomed in West Cumbria by more people than supported the presence of either BNFL or NIREX. Levels of pOlitical activity amongst local people were low. The particular socio-economic situation in West Cumbria appeared to have had an impact upon local opinion. Support extended to the local industry, and to BNFL in particular, far more than it did to the nuclear industry in general. The insular aspect of West Cumbrian culture has affected attitudes towards those groups perceived as 'outsiders', including the national media and environmental groups. It has also affected attitudes to the industry where public relations campaigns have been targeted at a national rather than a specifically West Cumbrian audience.

Neste trabalho é apresentado o potencial de remoção de íons estrôncio de soluções aquosas pelas fibras de coco na forma bruta e na forma ativada com peróxido de hidrogênio, 1% e 4%, em meio básico. Os experimentos de biossorção foram realizados em batelada com 2 mg.L-1 de solução de Sr(NO3)2 e foram estudadas as influências dos seguintes parâmetros: tempo de contato, pH e a eficiência de biossorção das fibras ativadas em comparação com a fibra de coco bruta (FCB). A caracterização das fibras antes e após o tratamento, e a presença de Sr2+ nas fibras foram realizadas por microscopia de varredura eletrônica com detector de espectroscopia de energia dispersiva, espectroscopia de difração de raios X, espectroscopia de infravermelho e por análise térmica. Dentre as fibras estudadas, a fibra de coco ativada com 1% H2O2 (FCA 1) apresentou a maior capacidade de biossorção: 3,6 mg.g-1, nas seguintes condições: 5 mg de biomassa em pH 6, após 90 minutos de tempo de contato à temperatura ambiente. A fibra de coco ativada com 4% H2O2 (FCA 2) levou a uma maior degradação dos constituintes da fibra e consequentemente a uma menor remoção de íons de Sr2+.Para os estudos de modelos de isotermas de biossorção de Sr2+, tanto a FCB quanto a FCA 1 ajustaram-se melhor ao modelo de Langmuir e à cinética de pseudo-segunda ordem. Os parâmetros termodinâmicos energia livre de Gibbs (ΔG) e coeficiente de distribuição (KD) foram -0,90 kJ.mol-1 e 265,3L.Kg-1 para a FCB e de -7,2 kJ.mol-1 e 824,3 L.Kg-1 para a FCA1. Esses resultados demonstraram que a FCA 1 possui uma boa eficiência para remover íons de Sr2+de resíduos químicos aquosos e é uma boa alternativa no tratamento de rejeitos radioativos líquidos contendo íons 90Sr. / This work presents the potential of strontium ions removal from aqueous solutions using coconut fiber in raw and treated form with hydrogen peroxide, 1% and 4%, in alkaline conditions. The biosorption experiments were performed in batch mode with 2 mg.L-1 solution of Sr(NO3)2 and the influence of the following parameters were studied: contact time and pH. It was also evaluate the biosorption efficiency of the treated coconut fibers in comparison with the raw coconut fiber (RCF). The fibers characterizations before and after treatment and the presence of the Sr2+ in the fibers were performed by scanning electron microscopy with a detector energy dispersive spectroscopy, diffraction of x-ray spectroscopy, infrared spectroscopy and thermal analysis. Among the studied fibers, the treated coconut fiber with 1% of H2O2 (TCF 1) showed the major biosorption capacity of 3.6 mg.g-1 in the following conditions: 5 mg of biomass at pH 6, 90 minutes of contact time at room temperature. Treated coconut fiber with 4% H2O2 (TCF 2) showed the lowest Sr2+ ions removal due to degradation of the fibers constituents. For studies of biosorption isotherms, both raw and treated coconut fiber (TCF 1) were fitted better to Langmuir model and the kinetics reaction was of pseudo-second order. The thermodynamic parameters Gibbs free energy (ΔG) and distribution coefficient (KD) were -0.90 kJ.mol-1 and 265.3 L.Kg-1 for RCF and of -7,2 kJ.mol-1 and 824.3L.Kg-1 for TCF 1. These results demonstrated that the TCF 1 has good efficiency for removing Sr2+ ions in the aqueous chemical waste and is a good alternative in treatment of liquid radioactive wastes containing 90Sr.

Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2010. / Committee Chair: Taillefert, Martial; Committee Member: DiChristina, Thomas; Committee Member: Sobecky, Patricia; Committee Member: Van Cappellen, Philippe; Committee Member: Webb, Samuel. Part of the SMARTech Electronic Thesis and Dissertation Collection.