Operationalising the use of Life Cycle Assessment to nuclear waste management

After decades of declining interest, nuclear energy is poised for a comeback in the UK, driven primarily by pledges and binding agreements on limiting greenhouse gas emissions, but also by increasing energy security concerns. However, the industry has yet to tackle some of its most crucial challenges regarding management of used nuclear fuels, and especially of highly radioactive wastes. Life Cycle Assessment (LCA) – indeed the most mature and also the only standardised life-cycle methodology – represents a widely accepted tool for quantifying the environmental impacts associated with goods or services and supporting decision-making processes. This Thesis aims at operationalising the use of LCA to nuclear waste management. After introducing the LCA standard methodology, the Thesis proceeds with a comprehensive review of methodologies for assessing radiological impacts – the lack of an appropriate approach for radiological impacts in LCA is in fact identified as the crucial barrier for its application to the industry, especially with respect to waste management. Building upon the main findings of the review, the Thesis presents an overarching framework and two practical methodologies – namely UCrad and the Critical Group Methodology (CGM) – for assessing radiological impacts of direct discharges, and crucially, of nuclear waste disposed of in a geological repository. The LCA and the methodologies for radiological impacts are then applied to two case studies. The first is a prospective attributional study that examines the current procedure for managing used nuclear fuels and the UK Government policy for disposal of nuclear waste in the UK. The objective is to identify hot-spots and suggest potential improvements. The study shows that the highest impacts are due to the production of chemicals required by the reprocessing process and the materials used for High Level Waste canisters rather than the construction and decommissioning of a final repository for nuclear waste. The second study focuses on future scenarios for managing used nuclear fuels in the UK, including direct disposal and four reprocessing options, and clearly demonstrates how LCA can be used to support decisions. Reprocessing of uranium, but especially of plutonium, is shown to be of crucial importance from an environmental perspective

Analysis of the functional role of nucleoporin Nup214 in nuclear transport and other cellular processes

Nuclear pore complexes (NPCs) provide the sole gateway between the cytoplasm and nucleus of eukaryotic cells and they act as mediator of all macromolecular exchange between these distinct subcellular compartments. Whereas the structure of the plant NPC has been studied already decades ago by distinct electron microscopy approaches, the characterization of its molecular components, the nucleoporins, has still remained largely elusive. In this review, we will focus on recent progress that has been made regarding the molecular composition of the plant NPC as well as on its role in nucleocytoplasmic transport and other processes, such as host-pathogen signaling in plants. In addition, we will discuss recent fi ndings on the vertebrate nucleoporins that appear to be absent in the plant NPC and their implications in cell organization related processes and diseases

Mid-infrared Gas Sensing Using Graphene Plasmons Tuned by Reversible Chemical Doping

Highly confined plasmon modes in nanostructured graphene can be used to detect tiny quantities of biological and gas molecules. In biosensing, a specific biomarker can be concentrated close to graphene, where the optical field is enhanced, by using an ad-hoc functional layer (e.g., antibodies). Inspired by this approach, in this paper we exploit the chemical and gas adsorption properties of an ultrathin polymer layer deposited on a nanostructured graphene surface to demonstrate a new gas sensing scheme. A proof-of-concept experiment using polyethylenimine (PEI) that is chemically reactive to CO2 molecules is presented. Upon CO2 adsorption, the sensor optical response changes because of PEI vibrational modes enhancement and shift in plasmon resonance, the latter related to polymer-induced doping of graphene. We show that the change in optical response is reversed during CO2 desorption. The demonstrated limit of detection (LOD) of 390 ppm corresponds to the lowest value detectable in ambient atmosphere, which can be lowered by operating in vacuum. By using specific adsorption polymers, the proposed sensing scheme can be easily extended to other relevant gases, for example, volatile organic compounds.Peer ReviewedPostprint (published version

Data on the environmental impacts of the Hellisheiði geothermal plant and on the carbon intensity of geothermal energy and other energy technologies

This data article is related to the research article “The environmental impacts and the carbon intensity of geothermal energy: A case study on the Hellisheiði plant”. The article reports numerical values of the results of the Life Cycle Assessment (LCA) study, which are reported only graphically and in an aggregated form in the main article. Data include normalised impacts, unaggregated environmental impacts of each life-cycle phase and activity in the foreground system, and results of Monte Carlo simulations. The article also includes data on the carbon intensity of other geothermal studies and alternative energy technologies, which were used for comparison in the associated research article

The environmental impacts and the carbon intensity of geothermal energy: A case study on the Hellisheiði plant

Geothermal energy, alongside other low-carbon and renewable energies, is set to play a key role in decarbonising the power generation industry to meet the Paris Agreement goal. Thus far the majority of Life Cycle Assessment (LCA) studies focused on enhanced geothermal plants. However, conventional geothermal plants that harness hydrothermal reservoirs dominate the production of electricity from geothermal energy worldwide. This article focuses on Hellisheiði, a combined heat and power double flash geothermal plant located in Iceland, with an installed capacity of 303.3 MW of electricity and 133 MW of hot water. The study has a twofold goal: (i) identify hot spots in the life cycle and, where possible, suggest improvements, and (ii) understand the potential of geothermal energy to decarbonise the power generation industry. First, a detailed LCA study has been performed on Hellisheiði, with cradle-to-grave system boundaries and detailed site-specific data obtained from the literature. The analysis identifies consumption of diesel for drilling and use of steel for wells casing and construction of the power plant as the main hot spots. Second, carbon intensities of electricity production for various possible configurations of the Hellisheiði power plant (including single flash, and power-only production) have been compared with those of other geothermal plants and other energy sources. Different allocation procedures have been used to allocate impacts between electricity and hot water where necessary, and Monte Carlo simulations have been used to estimate uncertainties of Hellisheiði's carbon intensities. The comparison shows that the carbon intensity of Hellisheiði is in the range of 15–24 g CO2-eq./kWh, which is similar to those of binary cycle geothermal plants, solar (photovoltaic) and hydropower, lower than other geothermal technologies and fossil-based technologies, and higher than nuclear and onshore wind

A brief overview on valorization of industrial tomato by-products using the biorefinery cascade approach

The industrial processing of tomato leads to substantial amounts of residues, typically known as tomato pomace or by-products, which can represent as much as 10% by weight of fresh tomatoes. At present, these residues are either used as feedstock for animals or, in the worst case, disposed of in landfills. This represents a significant waste because tomato pomace contains high-value compounds like lycopene, a powerful antioxidant, cutin, which can be used as a starting material for biopolymers, and pectin, a gelling agent. This article presents an overview of technologies that valorize tomato by-products by recovering added-value compounds as well as generating fuel for energy production. These technologies include operations for extraction, separation, and exploitation of lycopene, cutin and pectin, as well as the processes for conversion of the solid residues to fuels. Data collected from the review has been used to develop a biorefinery scheme with the related mass flow balance, for a scenario involving the tomato supply chain of Regione Campania in Italy, using tomato by-products as feedstock

Modalidade e asserção : um estudo semantico-progmatico dos enunciados de possibilidade epistanica

Orientador: Carlos VogtDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Estudos da LinguagemResumo: Não informadoAbstract: Not informed.MestradoMestre em Linguístic

A enunciação vacilante : formas do heterogeneo no discurso de si

Orientador: Eni OrlandiTese (doutorado) - Universidade Estadual de Campinas, Instituto de Estudos da LinguagemResumo: Este trabalho consiste numa investigação sobre um tipo de discurso que proponho chamar o discurso de si. Trata-se de um funcionamento que ocorre, empiricamente, em situações de conversação íntima, de caráter confidencial, em falas em situação terapêutica, em escritos íntimos, auto-reflexivos, como diários e em correspondências de caráter confidencial. No discurso de si o sujeito fala de si mesmo enquanto instância estritamente subjetiva: tenta representar, no corpo simbólico do discurso, estados psíquicos ¿ pensamentos e sentimentos experimentados. Esse processo se manifesta tipicamente sob a configuração do que denominei a enunciação vacilante. Na enunciação vacilante, tão logo um segmento de valor representacional é enunciado, seu poder de nominação é suspenso pelo atravessamento de modalizações cujo efeito é fazer tombar os sentidos que o dizer inscreve na dimensão da provisoriedade, da incompletude. Mas a constante busca do sentido próprio, a que o processo de modalização visa, faz cair o discurso na vacilação e acaba por rarefazer a referência, mostrando a emergência da não coincidência que afeta o dizer (Authier-Revuz, 1992). As diferentes modalizações encontradas no corpus são analisadas enquanto formas pelas quais a heterogeneidade do sujeito, do sentido e do dizer se manifestaAbstract: This thesis is an investigation about a kind of discourse that I propose to call the discourse of self. It occurs empirically at therapeutic settings, intimate conversations, personal writings as diaries and private and intimate correspondances. There is discourse of self when the subject speaks about himself in his strictly subjective condition: he tries to represent, at the symbolic level of discourse, psychological states ¿ thoughts and feelings experienced. The typical characteristic of discourse of self is the phenomenon that I called the wavering enunciation. In the wavering enunciation, as soon as a linguistic sequence having representative value is uttered, its nomination power is withheld by the crossing of modalizations whose effect is the crumbling of the sense in a provisional, incomplete dimension. But the search of the true, proper sense by the modalization process throws the discourse in the wavering and takes it far away from reference, showing the non coincidence that affects the saying (Authier-Revuz, 1992). The different modalizations founded in the corpus mean, through their particular forms, the arising of the heterogeneous condition of subject, sense and sayingDoutoradoDoutor em Linguístic

Reprocessing vs direct disposal of used nuclear fuels: The environmental impacts of future scenarios for the UK

The UK recently switched from a “nominal” twice-through cycle - whereby used nuclear fuels were reprocessed, but uranium and plutonium were not routinely reintroduced in the fuel cycle – to a once-through cycle, where used nuclear fuels are stored pending disposal. However, it is also the current strategy to keep other options open, including a twice-through cycle based on a different chemical separation process from the conventional PUREX. This article presents a comprehensive Life Cycle Assessment study of future scenarios for the back-end of the UK nuclear fuel cycle that aims at informing policy- and decision-makers. The study considers the direct disposal approach and four reprocessing scenarios envisaging different strategies for disposal and/or reuse of reprocessed uranium and plutonium, and adopts a consequential approach including only short-term effects. These primarily represent reductions in demand for uranium mining due to recycling of uranium and plutonium, and are modelled upon identification of a marginal technology. Several marginal technologies are explored because of the uncertainty regarding the actual response of the market. Results of the study show that recycling of uranium, but especially of plutonium is of paramount importance because of the avoided burdens associated with production of nuclear fuel from mined uranium. The reprocessing scenarios envisaging reprocessing of used nuclear fuels and recycling of both plutonium and uranium represent the most favourable options. The direct disposal approach may be advantageous only in terms of radiological impacts depending on the marginal technology chosen

Characterizing human health damage from ionizing radiation in life cycle assessment

Purpose: Although a wide number of industrial processes routinely release radionuclides into the environment, the resulting potential impacts on human health have been largely overlooked in life cycle assessment (LCA). As part of the Life Cycle Initiative project on Global Guidance for Life Cycle Impact Assessment Indicators and Methods (GLAM), we aim to develop a consensus-based source-to-damage framework and factors for characterizing human health damage from ionizing radiation in LCA. Methods: Our framework comprises four modules. The fate and exposure modules are based on UCrad, an earlier developed compartment-based environmental model for radionuclides. The focus of the present work is on the dose response and severity modules, which are based on most recent data from the International Committee on Radiological Protection and the Global Burden of Disease project series. The characterization factors are expressed in terms of DALY per kBq released. Results and discussions: We obtain characterization factors for 115 radionuclides and 8 environmental compartments. To evaluate our approach, we compare both effect factors (combining dose response and severity) and characterization factors with those proposed in earlier studies. Our analysis demonstrates that differences are explicable by the different approaches used in the fate and exposure modelling. We also test the sensitivity of our factors to different approaches for filling data gaps, suggesting that our factors are robust. Finally, we apply our factors in an illustrative case study on rice production and consumption under various scenarios to identify dominant radionuclides and how these differ when other approaches are used. Conclusions: Our framework is aligned with widely adopted methodologies for human health impact assessment, thus enabling robust comparisons, and covers nearly all radionuclides released by anthropogenic activities, including those that may arise from disposal of nuclear waste. Our factors are readily applicable for assessing radionuclide emissions in LCA. As next step we recommend (i) incorporating decay products into the fate model and (ii) integrating a model for indoor emissions of radon and indoor exposure to naturally occurring radionuclides (NORM)