Sistema de simulaci��n de escenarios de ciclos avanzados de combustible nuclear en transici��n = Simulation system for advanced fuel cycle transition scenarios

El estudio de los ciclos del combustible nuclear requieren de herramientas computacionales o "c��digos" vers��tiles para dar respuestas al problema multicriterio de evaluar los actuales ciclos o las capacidades de las diferentes estrategias y escenarios con potencial de desarrollo en a nivel nacional, regional o mundial. Por otra parte, la introducci��n de nuevas tecnolog��as para reactores y procesos industriales hace que los c��digos existentes requieran nuevas capacidades para evaluar la transici��n del estado actual del ciclo del combustible hacia otros m��s avanzados y sostenibles. Brevemente, esta tesis se centra en dar respuesta a las principales preguntas, en t��rminos econ��micos y de recursos, al an��lisis de escenarios de ciclos de combustible, en particular, para el an��lisis de los diferentes escenarios del ciclo del combustible de relativa importancia para Espa��a y Europa. Para alcanzar este objetivo ha sido necesaria la actualizaci��n y el desarrollo de nuevas capacidades del c��digo TR_EVOL (Transition Evolution code). Este trabajo ha sido desarrollado en el Programa de Innovaci��n Nuclear del CIEMAT desde el a��o 2010. Esta tesis se divide en 6 cap��tulos. El primer cap��tulo ofrece una visi��n general del ciclo de combustible nuclear, sus principales etapas y los diferentes tipos utilizados en la actualidad o en desarrollo para el futuro. Adem��s, se describen las fuentes de material nuclear que podr��an ser utilizadas como combustible (uranio y otros). Tambi��n se puntualizan brevemente una serie de herramientas desarrolladas para el estudio de estos ciclos de combustible nuclear. El cap��tulo 2 est�� dirigido a dar una idea b��sica acerca de los costes involucrados en la generaci��n de electricidad mediante energ��a nuclear. Aqu�� se presentan una clasificaci��n de estos costos y sus estimaciones, obtenidas en la bibliograf��a, y que han sido evaluadas y utilizadas en esta tesis. Se ha incluido tambi��n una breve descripci��n del principal indicador econ��mico utilizado en esta tesis, el ���coste nivelado de la electricidad���. El cap��tulo 3 se centra en la descripci��n del c��digo de simulaci��n desarrollado para el estudio del ciclo del combustible nuclear, TR_EVOL, que ha sido dise��ado para evaluar diferentes opciones de ciclos de combustibles. En particular, pueden ser evaluados las diversos reactores con, posiblemente, diferentes tipos de combustibles y sus instalaciones del ciclo asociadas. El m��dulo de evaluaciones econ��mica de TR_EVOL ofrece el coste nivelado de la electricidad haciendo uso de las cuatro fuentes principales de informaci��n econ��mica y de la salida del balance de masas obtenido de la simulaci��n del ciclo en TR_EVOL. Por otra parte, la estimaci��n de las incertidumbres en los costes tambi��n puede ser efectuada por el c��digo. Se ha efectuado un proceso de comprobaci��n cruzada de las funcionalidades del c��digo y se descrine en el Cap��tulo 4. El proceso se ha aplicado en cuatro etapas de acuerdo con las caracter��sticas m��s importantes de TR_EVOL, balance de masas, composici��n isot��pica y an��lisis econ��mico. As��, la primera etapa ha consistido en el balance masas del ciclo de combustible nuclear actual de Espa��a. La segunda etapa se ha centrado en la comprobaci��n de la composici��n isot��pica del flujo de masas mediante el la simulaci��n del ciclo del combustible definido en el proyecto CP-ESFR UE. Las dos ��ltimas etapas han tenido como objetivo validar el m��dulo econ��mico. De este modo, en la tercera etapa han sido evaluados los tres principales costes (financieros, operaci��n y mantenimiento y de combustible) y comparados con los obtenidos por el proyecto ARCAS, omitiendo los costes del fin del ciclo o Back-end, los que han sido evaluado solo en la cuarta etapa, haciendo uso de costes unitarios y par��metros obtenidos a partir de la bibliograf��a. En el cap��tulo 5 se analizan dos grupos de opciones del ciclo del combustible nuclear de relevante importancia, en t��rminos econ��micos y de recursos, para Espa��a y Europa. Para el caso espa��ol, se han simulado dos grupos de escenarios del ciclo del combustible, incluyendo estrategias de reproceso y extensi��n de vida de los reactores. Este an��lisis se ha centrado en explorar las ventajas y desventajas de reprocesado de combustible irradiado en un pa��s con una ���relativa��� peque��a cantidad de reactores nucleares. Para el grupo de Europa se han tratado cuatro escenarios, incluyendo opciones de transmutaci��n. Los escenarios incluyen los reactores actuales utilizando la tecnolog��a reactor de agua ligera y ciclo abierto, un reemplazo total de los reactores actuales con reactores r��pidos que queman combustible U-Pu MOX y dos escenarios del ciclo del combustible con transmutaci��n de act��nidos minoritarios en una parte de los reactores r��pidos o en sistemas impulsados por aceleradores dedicados a transmutaci��n. Finalmente, el cap��tulo 6 da las principales conclusiones obtenidas de esta tesis y los trabajos futuros previstos en el campo del an��lisis de ciclos de combustible nuclear. ABSTRACT The study of the nuclear fuel cycle requires versatile computational tools or ���codes��� to provide answers to the multicriteria problem of assessing current nuclear fuel cycles or the capabilities of different strategies and scenarios with potential development in a country, region or at world level. Moreover, the introduction of new technologies for reactors and industrial processes makes the existing codes to require new capabilities to assess the transition from current status of the fuel cycle to the more advanced and sustainable ones. Briefly, this thesis is focused in providing answers to the main questions about resources and economics in fuel cycle scenario analyses, in particular for the analysis of different fuel cycle scenarios with relative importance for Spain and Europe. The upgrade and development of new capabilities of the TR_EVOL code (Transition Evolution code) has been necessary to achieve this goal. This work has been developed in the Nuclear Innovation Program at CIEMAT since year 2010. This thesis is divided in 6 chapters. The first one gives an overview of the nuclear fuel cycle, its main stages and types currently used or in development for the future. Besides the sources of nuclear material that could be used as fuel (uranium and others) are also viewed here. A number of tools developed for the study of these nuclear fuel cycles are also briefly described in this chapter. Chapter 2 is aimed to give a basic idea about the cost involved in the electricity generation by means of the nuclear energy. The main classification of these costs and their estimations given by bibliography, which have been evaluated in this thesis, are presented. A brief description of the Levelized Cost of Electricity, the principal economic indicator used in this thesis, has been also included. Chapter 3 is focused on the description of the simulation tool TR_EVOL developed for the study of the nuclear fuel cycle. TR_EVOL has been designed to evaluate different options for the fuel cycle scenario. In particular, diverse nuclear power plants, having possibly different types of fuels and the associated fuel cycle facilities can be assessed. The TR_EVOL module for economic assessments provides the Levelized Cost of Electricity making use of the TR_EVOL mass balance output and four main sources of economic information. Furthermore, uncertainties assessment can be also carried out by the code. A cross checking process of the performance of the code has been accomplished and it is shown in Chapter 4. The process has been applied in four stages according to the most important features of TR_EVOL. Thus, the first stage has involved the mass balance of the current Spanish nuclear fuel cycle. The second stage has been focused in the isotopic composition of the mass flow using the fuel cycle defined in the EU project CP-ESFR. The last two stages have been aimed to validate the economic module. In the third stage, the main three generation costs (financial cost, O&M and fuel cost) have been assessed and compared to those obtained by ARCAS project, omitting the back-end costs. This last cost has been evaluated alone in the fourth stage, making use of some unit cost and parameters obtained from the bibliography. In Chapter 5 two groups of nuclear fuel cycle options with relevant importance for Spain and Europe are analyzed in economic and resources terms. For the Spanish case, two groups of fuel cycle scenarios have been simulated including reprocessing strategies and life extension of the current reactor fleet. This analysis has been focused on exploring the advantages and disadvantages of spent fuel reprocessing in a country with relatively small amount of nuclear power plants. For the European group, four fuel cycle scenarios involving transmutation options have been addressed. Scenarios include the current fleet using Light Water Reactor technology and open fuel cycle, a full replacement of the initial fleet with Fast Reactors burning U-Pu MOX fuel and two fuel cycle scenarios with Minor Actinide transmutation in a fraction of the FR fleet or in dedicated Accelerator Driven Systems. Finally, Chapter 6 gives the main conclusions obtained from this thesis and the future work foreseen in the field of nuclear fuel cycle analysis.

Conceptual design of offshore platform supply vessel based on hybrid diesel generator-fuel cell power plant

Nowadays increasing fuel prices and upcoming pollutant emission regulations are becoming a growing concern for the shipping industry worldwide. While fuel prices will keep rising in future years, the new International Convention for the Prevention of Pollution from Ships (MARPOL) and Sulphur Emissions Control Areas (SECA) regulations will forbid ships to use heavy fuel oils at certain situations. To fulfil with these regulations, the next step in the marine shipping business will comprise the use of cleaner fuels on board as well as developing new propulsion concept. In this work a new conceptual marine propulsion system is developed, based on the integration of diesel generators with fuel cells in a 2850 metric tonne of deadweight platform supply vessel. The efficiency of the two 250 kW methanol-fed Solid Oxide Fuel Cell (SOFC) system installed on board combined with the hydro dynamically optimized design of the hull of the ship will allow the ship to successfully operate at certain modes of operation while notably reduce the pollutant emissions to the atmosphere. Besides the cogeneration heat obtained from the fuel cell system will be used to answer different heating needs on board the vessel

Desulfurization of pyrolysis fuel produced from waste lube oils, tyres and plastics

Sulphur compounds remaining in petroleum fractions from topping, hydroskimming or deep conversion processes are a growing concern for oil refiners since in the lapse of a few years the sulphur specification for motor fuels has dropped from 500 mg/kg to 10 mg/kg in most European countries. This increasingly stringent regulation has forced refineries to greatly improve their hydrodesulfurization units, increasing the desulfurization rates and thus consuming huge amounts of hydrogen.

Fuel poverty analysis in three spanish autonomous regions. Some retrofitting policy considerations

A person is to be regarded as living ���in fuel poverty��� if he is a member of a household living on a lower income in a home which cannot be kept warm at a reasonable cost. This situation is mainly triggered by three factors: low household income, lack of energy efficiency and high energy invoices. Some European countries have already made some advantages towards officially defining fuel poverty in their countries. Nevertheless, in Spain only some research has been done and an official definition of the term is yet to come. This research explores the relation among households��� income, energy expenditure and housing stock in three autonomous regions in Spain in order to evaluate the housing stock of the fuel poor as well as to identify those households more in need. The results of the research allow establishing energy retrofitting priorities of existing housing stock as well as identifying current retrofitting policies limitations on order to tackle fuel poverty.

Electrochemical study of platinum deposited by electron beam evaporation for application as fuel cell electrodes

Platinum is the most used catalyst in electrodes for fuel cells due to its high catalytic activity. Polymer electrolyte and direct methanol fuel cells usually include Pt as catalyst in their electrodes. In order to diminish the cost of such electrodes, different Pt deposition methods that permit lowering the metal load whilst maintaining their electroactivity, are being investigated. In this work, the behaviour of electron beam Pt (e-beam Pt) deposited electrodes for fuel cells is studied. Three different Pt loadings have been investigated. The electrochemical behaviour by cyclic voltammetry in H2SO4, HClO4 and in HClO4+MeOH before and after the Pt deposition on carbon cloth has been analysed. The Pt improves the electrochemical properties of the carbon support used. The electrochemical performance of e-beam Pt deposited electrodes was finally studied in a single direct methanol fuel cell (DMFC) and the obtained results indicate that this is a promising and adequate method to prepare fuel cell electrodes.

Desenvolvimento de um elemento combust��vel instrumentado para o reator de pesquisa IEA-R1

Ap��s o aumento de pot��ncia do reator IEA-R1 de 2 MW para 5 MW observou-se um aumento da taxa de corros��o nas placas laterais de alguns elementos combust��veis e algumas d��vidas surgiram com rela����o ao valor de vaz��o utilizada nas an��lises termo-hidr��ulicas. A fim de esclarecer e medir a distribui����o de vaz��o real pelos elementos combust��veis que comp��e o n��cleo do reator IEA-R1, um elemento combust��vel prot��tipo, sem material nuclear, chamado DMPV-01 (Dispositivo para Medida de Press��o e Vaz��o), em escala real, foi projetado e constru��do em alum��nio. A vaz��o no canal entre dois elementos combust��veis �� muito dif��cil de estimar ou ser medida. Esta vaz��o �� muito importante no processo de resfriamento das placas laterais. Este trabalho apresenta a concep����o e constru����o de um elemento combust��vel instrumentado para medir a temperatura real nestas placas laterais para melhor avaliar as condi����es de resfriamento do combust��vel. Quatorze termopares foram instalados neste elemento combust��vel instrumentado. Quatro termopares em cada canal lateral e quatro no canal central, al��m de um termopar no bocal de entrada e outro no bocal de sa��da do elemento. Existem tr��s termopares para medida de temperatura do revestimento e um para a temperatura do fluido em cada canal. Tr��s s��ries de experimentos, para tr��s configura����es distintas, foram realizadas com o elemento combust��vel instrumentado. Em dois experimentos uma caixa de alum��nio foi instalada ao redor do n��cleo para reduzir o escoamento transverso entre os elementos combust��veis e medir o impacto na temperatura das placas externas. Dada a tamanha quantidade de informa����es obtidas e sua utilidade no projeto, melhoria e capacita����o na constru����o, montagem e fabrica����o de elementos combust��veis instrumentados, este projeto constitui um importante marco no estudo de n��cleos de reatores de pesquisa. As solu����es propostas podem ser amplamente utilizadas para outros reatores de pesquisa.

A Case Study of the Economic and Environmental Impacts from a Bio-fuel Facility (Southwest Georgia Ethanol, LLC) on the Surrounding Communities, Southwest Georgia

Bio-fuels such as ethanol provide an extraordinary opportunity to address our dependency on foreign oil. This case study examines the economic and environmental impacts associated with constructing and operating a dry mill ethanol manufacturing facility in a Southwest Georgia town and surrounding communities. The case study found that the plant had little impact on air quality, water quality, and habitat fragmentation. However, economic results showed the plant produced $1.5 million in tax revenues, and 86 jobs. Ethanol producers and communities must consider both the economic and environmental impacts on a local community when searching or attracting a bio-fuels plant. Likewise, communities should be aware of these challenges when attracting ethanol production plants.

Electrochemical analysis of the performance of carbon supported Pd nanoparticles for direct formic acid fuel cells: from gold supported electrodes to catalyst-coated membranes

In this work carbon supported Pd nanoparticles were prepared and used as electrocatalysts for formic acid electrooxidation fuel cells. The influence of some relevant parameters such as the nominal Pt loading, the Nafion/total solids ratio as well as the Pd loading towards formic acid electrooxidation was evaluated using gold supported catalytic layer electrodes which were prepared using a similar methodology to that employed in the preparation of conventional catalyst coated membranes (CCM). The results obtained show that, for constant Pd loading, the nominal Pd loading and the Nafion percentage on the catalytic layer do not play an important role on the resulting electrocatalytic properties. The main parameter affecting the electrocatalytic activity of the electrodes seems to be the Pd loading, although the resulting activity is not directly proportional to the increased Pd loading. Thus, whereas the Pd loading is multiplied by a factor of 10, the activity is only twice which evidences an important decrease in the Pd utilization. In fact, the results obtained suggest the active layer is the outer one being clearly independent of the catalytic layer thickness. Finally, catalyst coated membranes with Pd catalyst loadings of 0.1, 0.5 and 1.2 mg cm-2 were also tested in a breathing direct formic acid fuel cell.

Viability study of automobile shredder residue as fuel

Car Fluff samples collected from a shredding plant in Italy were classified based on particle size, and three different size fractions were obtained in this way. A comparison between these size fractions and the original light fluff was made from two different points of view: (i) the properties of each size fraction as a fuel were evaluated and (ii) the pollutants evolved when each size fraction was subjected to combustion were studied. The aim was to establish which size fraction would be the most suitable for the purposes of energy recovery. The light fluff analyzed contained up to 50 wt.% fines (particle size < 20 mm). However, its low calorific value and high emissions of polychlorinated dioxins and furans (PCDD/Fs), generated during combustion, make the fines fraction inappropriate for energy recovery, and therefore, landfilling would be the best option. The 50���100 mm fraction exhibited a high calorific value and low PCDD/F emissions were generated when the sample was combusted, making it the most suitable fraction for use as refuse-derived fuel (RDF). Results obtained suggest that removing fines from the original ASR sample would lead to a material product that is more suitable for use as RDF.

Conversion of low density polyethylene into fuel through co-processing with vacuum gas oil in a fluid catalytic cracking riser reactor

In this work, mixtures of vacuum gas oil and low density polyethylene, a major component of common industrial and consumer household plastics, were pyrolytically co-processed in a fluid catalytic cracking (FCC) riser reactor as a viable alternative for the energy and petrochemical revalorisation of plastic wastes into valuable petrochemical feedstocks and fuel within an existing industrial technology. Using equilibrium FCC catalyst, the oil���polymer blends were catalytically cracked at different processing conditions of temperatures between 773 K and 973 K and catalyst feed ratios of 5:1, 7:1 and 10:1. The influence of each of these processing parameters on the cracking gas and liquid yield patterns were studied and presented. Further analysed and presented are the different compositional distributions of the obtained liquids and gaseous products. The analysis of the results obtained revealed that with very little modifications to existing process superstructure, yields and compositional distributions of products from the fluid catalytic cracking of the oil���polymer blend in many cases were very similar to those of the processed oil feedstock, bringing to manifest the viability of the feedstock co-processing without significant detriments to FCC product yields and quality.

Ethanol dehydration via azeotropic distillation with gasoline fractions as entrainers: A pilot-scale study of the manufacture of an ethanol���hydrocarbon fuel blend

We establish experimentally and through simulations the economic and technical viability of dehydrating ethanol by means of azeotropic distillation, using a hydrocarbon as entrainer. The purpose of this is to manufacture a ready-to-use ethanol���hydrocarbon fuel blend. In order to demonstrate the feasibility of this proposition, we have tested an azeotropic water���ethanol feed mixture, using a hydrocarbon as entrainer, in a semi pilot-plant scale distillation column. Four different hydrocarbons (hexane, cyclohexane, isooctane, and toluene) that are representative of the hydrocarbons present in ordinary gasoline have been tested. Each of these hydrocarbons was tested separately in experiments under conditions of constant feed rate and variable reboiler heat duty. The experimentally obtained results are compared with results calculated by a simulator. Finally, the proposed and traditional ethanol dehydration processes are compared to ascertain the advantages of the former over the latter.

The combined effect of plastics and food waste accelerates the thermal decomposition of refuse-derived fuels and fuel blends

Mechanical treatments such as shredding or extrusion are applied to municipal solid wastes (MSW) to produce refuse-derived fuels (RDF). In this way, a waste fraction (mainly composed by food waste) is removed and the quality of the fuel is improved. In this research, simultaneous thermal analysis (STA) was used to investigate how different mechanical treatments applied to MSW influence the composition and combustion behaviour of fuel blends produced by combining MSW or RDF with wood in different ratios. Shredding and screening resulted in a more efficient mechanical treatment than extrusion to reduce the chlorine content in a fuel, which would improve its quality. This study revealed that when plastics and food waste are combined in the fuel matrix, the thermal decomposition of the fuels are accelerated. The combination of MSW or RDF and woody materials in a fuel blend has a positive impact on its decomposition.