Environmental risk assessment in open pit blasting operations: compliance with ISO 31010:2010

All activities of an organization involve risks that should be managed. The risk management process aids decision making by taking account of uncertainty and the possibility of future events or circumstances (intended or unintended) and their effects on agreed objectives. With that idea, new ISO Standard has been drawn up. ISO 31010 has been recently issued which provides a structured process that identifies how objectives may be affected, and analyses the risk in term of consequences and their probabilities before deciding on whether further treatment is required. In this lecture, that ISO Standard has been adapted to Open Pit Blasting Operations, focusing in Environmental effects which can be managed properly. Technique used is Fault Tree Analysis (FTA), which is applied in all possible scenarios, providing to Blasting Professionals the tools to identify, analyze and manage environmental effects in blasting operations. Also this lecture can help to minimize each effect, studying each case. This paper also can be useful to Project Managers and Occupational Health and Safety Departments (OH&S) because blasting operations can be evaluated and compared one to each other to determine the risks that should be managed in different case studies. The environmental effects studied are: ground vibrations, flyrock and air overpressure (airblast). Sometimes, blasting operations are carried out near populated areas where environmental effects may impose several limitations on the use of explosives. In those cases, where these factors approach certain limits, National Standards and Regulations have to be applied.

A methodology proposal to obtain operational parameter forecasts and operational risk assessment in container terminals

Las terminales de contenedores son sistemas complejos en los que un elevado número de actores económicos interactúan para ofrecer servicios de alta calidad bajo una estricta planificación y objetivos económicos. Las conocidas como "terminales de nueva generación" están diseñadas para prestar servicio a los mega-buques, que requieren tasas de productividad que alcanzan los 300 movimientos/ hora. Estas terminales han de satisfacer altos estándares dado que la competitividad entre terminales es elevada. Asegurar la fiabilidad de las planificaciones del atraque es clave para atraer clientes, así como reducir al mínimo el tiempo que el buque permanece en el puerto. La planificación de las operaciones es más compleja que antaño, y las tolerancias para posibles errores, menores. En este contexto, las interrupciones operativas deben reducirse al mínimo. Las principales causas de dichas perturbaciones operacionales, y por lo tanto de incertidumbre, se identifican y caracterizan en esta investigación. Existen una serie de factores que al interactuar con la infraestructura y/o las operaciones desencadenan modos de fallo o parada operativa. Los primeros pueden derivar no solo en retrasos en el servicio sino que además puede tener efectos colaterales sobre la reputación de la terminal, o incluso gasto de tiempo de gestión, todo lo cual supone un impacto para la terminal. En el futuro inmediato, la monitorización de las variables operativas presenta gran potencial de cara a mejorar cualitativamente la gestión de las operaciones y los modelos de planificación de las terminales, cuyo nivel de automatización va en aumento. La combinación del criterio experto con instrumentos que proporcionen datos a corto y largo plazo es fundamental para el desarrollo de herramientas que ayuden en la toma de decisiones, ya que de este modo estarán adaptadas a las auténticas condiciones climáticas y operativas que existen en cada emplazamiento. Para el corto plazo se propone una metodología con la que obtener predicciones de parámetros operativos en terminales de contenedores. Adicionalmente se ha desarrollado un caso de estudio en el que se aplica el modelo propuesto para obtener predicciones de la productividad del buque. Este trabajo se ha basado íntegramente en datos proporcionados por una terminal semi-automatizada española. Por otro lado, se analiza cómo gestionar, evaluar y mitigar el efecto de las interrupciones operativas a largo plazo a través de la evaluación del riesgo, una forma interesante de evaluar el effecto que eventos inciertos pero probables pueden generar sobre la productividad a largo plazo de la terminal. Además se propone una definición de riesgo operativo junto con una discusión de los términos que representan con mayor fidelidad la naturaleza de las actividades y finalmente, se proporcionan directrices para gestionar los resultados obtenidos. Container terminals are complex systems where a large number of factors and stakeholders interact to provide high-quality services under rigid planning schedules and economic objectives. The socalled next generation terminals are conceived to serve the new mega-vessels, which are demanding productivity rates up to 300 moves/hour. These terminals need to satisfy high standards because competition among terminals is fierce. Ensuring reliability in berth scheduling is key to attract clients, as well as to reduce at a minimum the time that vessels stay the port. Because of the aforementioned, operations planning is becoming more complex, and the tolerances for errors are smaller. In this context, operational disturbances must be reduced at a minimum. The main sources of operational disruptions and thus, of uncertainty, are identified and characterized in this study. External drivers interact with the infrastructure and/or the activities resulting in failure or stoppage modes. The later may derive not only in operational delays but in collateral and reputation damage or loss of time (especially management times), all what implies an impact for the terminal. In the near future, the monitoring of operational variables has great potential to make a qualitative improvement in the operations management and planning models of terminals that use increasing levels of automation. The combination of expert criteria with instruments that provide short- and long-run data is fundamental for the development of tools to guide decision-making, since they will be adapted to the real climatic and operational conditions that exist on site. For the short-term a method to obtain operational parameter forecasts in container terminals. To this end, a case study is presented, in which forecasts of vessel performance are obtained. This research has been entirely been based on data gathered from a semi-automated container terminal from Spain. In the other hand it is analyzed how to manage, evaluate and mitigate disruptions in the long-term by means of the risk assessment, an interesting approach to evaluate the effect of uncertain but likely events on the long-term throughput of the terminal. In addition, a definition for operational risk evaluation in port facilities is proposed along with a discussion of the terms that better represent the nature of the activities involved and finally, guidelines to manage the results obtained are provided.

Assessment of oral bioaccessibility of arsenic in playground soil in Madrid (Spain): A three-method comparison and implications for risk assessment

Three methodologies to assess As bioaccessibility were evaluated using playgroundsoil collected from 16 playgrounds in Madrid, Spain: two (Simplified Bioaccessibility Extraction Test: SBET, and hydrochloric acid-extraction: HCl) assess gastric-only bioaccessibility and the third (Physiologically Based Extraction Test: PBET) evaluates mouth–gastric–intestinal bioaccessibility. Aqua regia-extractable (pseudo total) As contents, which are routinely employed in riskassessments, were used as the reference to establish the following percentages of bioaccessibility: SBET – 63.1; HCl – 51.8; PBET – 41.6, the highest values associated with the gastric-only extractions. For Madridplaygroundsoils – characterised by a very uniform, weakly alkaline pH, and low Fe oxide and organic matter contents – the statistical analysis of the results indicates that, in contrast with other studies, the highest percentage of As in the samples was bound to carbonates and/or present as calcium arsenate. As opposed to the As bound to Fe oxides, this As is readily released in the gastric environment as the carbonate matrix is decomposed and calcium arsenate is dissolved, but some of it is subsequently sequestered in unavailable forms as the pH is raised to 5.5 to mimic intestinal conditions. The HCl extraction can be used as a simple and reliable (i.e. low residual standard error) proxy for the more expensive, time consuming, and error-prone PBET methodology. The HCl method would essentially halve the estimate of carcinogenic risk for children playing in Madridplaygroundsoils, providing a more representative value of associated risk than the pseudo-total concentrations used at present

Geochemistry and risk assessment of street dust in Luanda, Angola, a tropical urban environment

A total of 92 samples of street dust were collected in Luanda, Angola, were sieved below 100 μm, and analysed by ICP-MS for 35 elements after an aqua-regia digestion. The concentration and spatial heterogeneity of trace elements in the street dust of Luanda are generally lower than in most industrialized cities in the Northern hemisphere. These observations reveal a predominantly “natural” origin for the street dust in Luanda, which is also manifested in that some geochemical processes that occur in natural soils are preserved in street dust: the separation of uranium from thorium, and the retention of the former by carbonate materials, or the high correlation between arsenic and vanadium due to their common mode of adsorption on solid particles in the form of oxyanions. The only distinct anthropogenic fingerprint in the composition of Luanda's street dust is the association Pb–Cd–Sb–Cu (and to a lesser extent, Ba–Cr–Zn). The use of risk assessment strategies has proved helpful in identifying the routes of exposure to street dust and the trace elements therein of most concern in terms of potential adverse health effects. In Luanda the highest levels of risk seem to be associated (a) with the presence of As and Pb in the street dust and (b) with the route of ingestion of dust particles, for all the elements included in the study except Hg, for which inhalation of vapours presents a slightly higher risk than ingestion. However, given the large uncertainties associated with the estimates of toxicity values and exposure factors, and the absence of site-specific biometric factors, these results should be regarded as preliminary and further research should be undertaken before any definite conclusions regarding potential health effects are drawn.

Risk assessment of the spanish national railway system

The principal risks in the railway industry are mainly associated with collisions, derailments and level crossing accidents. An understanding of the nature of previous accidents on the railway network is required to identify potential causes and develop safety systems and deploy safety procedures. Risk assessment is a process for determining the risk magnitude to assist with decision-making. We propose a three-step methodology to predict the mean number of fatalities in railway accidents. The first is to predict the mean number of accidents by analyzing generalized linear models and selecting the one that best fits to the available historical data on the basis of goodness-offit statistics. The second is to compute the mean number of fatalities per accident and the third is to estimate the mean number of fatalities. The methodology is illustrated on the Spanish railway system. Statistical models accounting for annual and grouped data for the 1992-2009 time period have been analyzed. After identifying the models for broad and narrow gauges, we predicted mean number of accidents and the number of fatalities for the 2010-18 time period.

Bioaccessibility of heavy metals and risk assessment in urban gardens of Madrid

Human health problems and solutions. Urban gardening has spread worldwide in recent years as it enhances food security and selfsupply and promotes community integration. However urban soils are significantly enriched in trace elements relative to background levels. Exposure to the soil in urban gardens may therefore result in adverse health effects depending on the degree of contact during gardening, infant recreational activities and ingestion of vegetables grown in them. In order to evaluate this potential risk, 36 composite samples were collected from the top 20 cm of the soil of 6 urban gardens in Madrid. The aqua regia (pseudototal) and glycine-extractable (bioaccessible) concentrations of Co, Cr, Cu, Ni, Pb and Zn were determined by atomic absorption spectrophotometry. Additionally, pH, texture, Fe, Ca, and Mn concentrations, and organic matter and calcium carbonate contents were determined in all urban gardens and their influence on trace element bioaccessibility was analyzed.

Bioaccessibility of metals and human health risk assessment in community urban gardens

Pseudo-total (i.e. aqua regia extractable) and gastric-bioaccessible (i.e. glycine + HCl extractable) concentrations of Ca, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined in a total of 48 samples collected from six community urban gardens of different characteristics in the city of Madrid (Spain). Calcium carbonate appears to be the soil property that determines the bioaccessibility of a majority of those elements, and the lack of influence of organic matter, pH and texture can be explained by their low levels in the samples (organic matter) or their narrow range of variation (pH and texture). A conservative risk assessment with bioaccessible concentrations in two scenarios, i.e. adult urban farmers and children playing in urban gardens, revealed acceptable levels of risk, but with large differences between urban gardens depending on their history of land use and their proximity to busy areas in the city center. Only in a worst-case scenario in which children who use urban gardens as recreational areas also eat the produce grown in them would the risk exceed the limits of acceptability

A fuzzy MCDA framework for safety assessment in the remediation of a uranium mill tailings site in Ukraine

The Pridneprovsky Chemical Plant was one of the largest uranium processing enterprises in the former USSR, producing a huge amount of uranium residues. The Zapadnoe tailings site contains most of these residues. We propose a theoretical framework based on multicriteria decision analysis and fuzzy logic to analyze different remediation alternatives for the Zapadnoe tailings, which simultaneously accounts for potentially conflicting economic, social and environmental objectives. We build an objective hierarchy that includes all the relevant aspects. Fuzzy rather than precise values are proposed for use to evaluate remediation alternatives against the different criteria and to quantify preferences, such as the weights representing the relative importance of criteria identified in the objective hierarchy. Finally, we suggest that remediation alternatives should be evaluated by means of a fuzzy additive multi-attribute utility function and ranked on the basis of the respective trapezoidal fuzzy number representing their overall utility.

A modelling language for the resilience assessment of networked systems of systems

Systems of Systems (SoS) present challenging features and existing tools result often inadequate for their analysis, especially for heteregeneous networked infrastructures. Most accident scenarios in networked systems cannot be addressed by a simplistic black or white (i.e. functioning or failed) approach. Slow deviations from nominal operation conditions may cause degraded behaviours that suddenly end up into unexpected malfunctioning, with large portions of the network affected. In this paper,we present a language for modelling networked SoS. The language makes it possible to represent interdependencies of various natures, e.g. technical, organizational and human. The representation of interdependencies is based on control relationships that exchange physical quantities and related information. The language also makes it possible the identification of accident scenarios, by representing the propagation of failure events throughout the network. The results can be used for assessing the effectiveness of those mechanisms and measures that contribute to the overall resilience, both in qualitative and quantitative terms. The presented modelling methodology is general enough to be applied in combination with already existing system analysis techniques, such as risk assessment, dependability and performance evaluation

Effect of Biodiversity Changes in Disease Risk: Exploring Disease Emergence in a Plant-Virus System

The effect of biodiversity on the ability of parasites to infect their host and cause disease (i.e. disease risk) is a major question in pathology, which is central to understand the emergence of infectious diseases, and to develop strategies for their management. Two hypotheses, which can be considered as extremes of a continuum, relate biodiversity to disease risk: One states that biodiversity is positively correlated with disease risk (Amplification Effect), and the second predicts a negative correlation between biodiversity and disease risk (Dilution Effect). Which of them applies better to different host-parasite systems is still a source of debate, due to limited experimental or empirical data. This is especially the case for viral diseases of plants. To address this subject, we have monitored for three years the prevalence of several viruses, and virus-associated symptoms, in populations of wild pepper (chiltepin) under different levels of human management. For each population, we also measured the habitat species diversity, host plant genetic diversity and host plant density. Results indicate that disease and infection risk increased with the level of human management, which was associated with decreased species diversity and host genetic diversity, and with increased host plant density. Importantly, species diversity of the habitat was the primary predictor of disease risk for wild chiltepin populations. This changed in managed populations where host genetic diversity was the primary predictor. Host density was generally a poorer predictor of disease and infection risk. These results support the dilution effect hypothesis, and underline the relevance of different ecological factors in determining disease/infection risk in host plant populations under different levels of anthropic influence. These results are relevant for managing plant diseases and for establishing conservation policies for endangered plant species.

CO2 soil flux baseline at the technological development plant for CO2 injection at Hontomin (Burgos, Spain)

From the end of 2013 and during the following two years, 20 kt of CO2sc are planned to be injected in a saline reservoir (1500 m depth) at the Hontomín site (NE Spain). The target aquifers are Lower Jurassic limestone formations which are sealed by Lower Cretaceous clay units at the Hontomín site (NE Spain). The injection of CO2 is part of the activities committed in the Technology Development phase of the EC-funded OXYCFB300 project (European Energy Program for Recovery – EEPR, http://www.compostillaproject.eu), which include CO2 injection strategies, risk assessment, and testing and validating monitoring methodologies and techniques. Among the monitoring works, the project is intended to prove that present-day technology is able to monitor the evolution of injected CO2 in the reservoir and to detect potential leakage. One of the techniques is the measurement of CO2 flux at the soil–atmosphere interface, which includes campaigns before, during and after the injection operations. In this work soil CO2 flux measurements in the vicinity of oil borehole, drilled in the eighties and named H-1 to H-4, and injection and monitoring wells were performed using an accumulation chamber equipped with an IR sensor. Seven surveys were carried out from November 2009 to summer 2011. More than 4000 measurements were used to determine the baseline flux of CO2 and its seasonal variations. The measured values were low (from 5 to 13 g m−2 day−1) and few outliers were identified, mainly located close to the H-2 oil well. Nevertheless, these values cannot be associated to a deep source of CO2, being more likely related to biological processes, i.e. soil respiration. No anomalies were recognized close to the deep fault system (Ubierna Fault) detected by geophysical investigations. There, the CO2 flux is indeed as low as other measurement stations. CO2 fluxes appear to be controlled by the biological activity since the lowest values were recorded during autumn-winter seasons and they tend to increase in warm periods. Two reference CO2 flux values (UCL50 of 5 g m−2 d−1 for non-ploughed areas in autumn–winter seasons and 3.5 and 12 g m−2 d−1 for in ploughed and non-ploughed areas, respectively, in spring–summer time, and UCL99 of 26 g m−2 d−1 for autumn–winter in not-ploughed areas and 34 and 42 g m−2 d−1 for spring–summer in ploughed and not-ploughed areas, respectively) were calculated. Fluxes higher than these reference values could be indicative of possible leakage during the operational and post-closure stages of the storage project.

Efficient algorithms for dynamic probabilistic safety assessment. An application to convex damage domain.

The design of nuclear power plant has to follow a number of regulations aimed at limiting the risks inherent in this type of installation. The goal is to prevent and to limit the consequences of any possible incident that might threaten the public or the environment. To verify that the safety requirements are met a safety assessment process is followed. Safety analysis is as key component of a safety assessment, which incorporates both probabilistic and deterministic approaches. The deterministic approach attempts to ensure that the various situations, and in particular accidents, that are considered to be plausible, have been taken into account, and that the monitoring systems and engineered safety and safeguard systems will be capable of ensuring the safety goals. On the other hand, probabilistic safety analysis tries to demonstrate that the safety requirements are met for potential accidents both within and beyond the design basis, thus identifying vulnerabilities not necessarily accessible through deterministic safety analysis alone. Probabilistic safety assessment (PSA) methodology is widely used in the nuclear industry and is especially effective in comprehensive assessment of the measures needed to prevent accidents with small probability but severe consequences. Still, the trend towards a risk informed regulation (RIR) demanded a more extended use of risk assessment techniques with a significant need to further extend PSA’s scope and quality. Here is where the theory of stimulated dynamics (TSD) intervenes, as it is the mathematical foundation of the integrated safety assessment (ISA) methodology developed by the CSN(Consejo de Seguridad Nuclear) branch of Modelling and Simulation (MOSI). Such methodology attempts to extend classical PSA including accident dynamic analysis, an assessment of the damage associated to the transients and a computation of the damage frequency. The application of this ISA methodology requires a computational framework called SCAIS (Simulation Code System for Integrated Safety Assessment). SCAIS provides accident dynamic analysis support through simulation of nuclear accident sequences and operating procedures. Furthermore, it includes probabilistic quantification of fault trees and sequences; and integration and statistic treatment of risk metrics. SCAIS comprehensively implies an intensive use of code coupling techniques to join typical thermal hydraulic analysis, severe accident and probability calculation codes. The integration of accident simulation in the risk assessment process and thus requiring the use of complex nuclear plant models is what makes it so powerful, yet at the cost of an enormous increase in complexity. As the complexity of the process is primarily focused on such accident simulation codes, the question of whether it is possible to reduce the number of required simulation arises, which will be the focus of the present work. This document presents the work done on the investigation of more efficient techniques applied to the process of risk assessment inside the mentioned ISA methodology. Therefore such techniques will have the primary goal of decreasing the number of simulation needed for an adequate estimation of the damage probability. As the methodology and tools are relatively recent, there is not much work done inside this line of investigation, making it a quite difficult but necessary task, and because of time limitations the scope of the work had to be reduced. Therefore, some assumptions were made to work in simplified scenarios best suited for an initial approximation to the problem. The following section tries to explain in detail the process followed to design and test the developed techniques. Then, the next section introduces the general concepts and formulae of the TSD theory which are at the core of the risk assessment process. Afterwards a description of the simulation framework requirements and design is given. Followed by an introduction to the developed techniques, giving full detail of its mathematical background and its procedures. Later, the test case used is described and result from the application of the techniques is shown. Finally the conclusions are presented and future lines of work are exposed.

Aplicación de la metodología ISA al análisis de la secuencia de pérdida del sistema de agua de refrigeración de componentes en una central nuclear con reactor de agua a presión

La metodología Integrated Safety Analysis (ISA), desarrollada en el área de Modelación y Simulación (MOSI) del Consejo de Seguridad Nuclear (CSN), es un método de Análisis Integrado de Seguridad que está siendo evaluado y analizado mediante diversas aplicaciones impulsadas por el CSN; el análisis integrado de seguridad, combina las técnicas evolucionadas de los análisis de seguridad al uso: deterministas y probabilistas. Se considera adecuado para sustentar la Regulación Informada por el Riesgo (RIR), actual enfoque dado a la seguridad nuclear y que está siendo desarrollado y aplicado en todo el mundo. En este contexto se enmarcan, los proyectos Safety Margin Action Plan (SMAP) y Safety Margin Assessment Application (SM2A), impulsados por el Comité para la Seguridad de las Instalaciones Nucleares (CSNI) de la Agencia de la Energía Nuclear (NEA) de la Organización para la Cooperación y el Desarrollo Económicos (OCDE) en el desarrollo del enfoque adecuado para el uso de las metodologías integradas en la evaluación del cambio en los márgenes de seguridad debidos a cambios en las condiciones de las centrales nucleares. El comité constituye un foro para el intercambio de información técnica y de colaboración entre las organizaciones miembro, que aportan sus propias ideas en investigación, desarrollo e ingeniería. La propuesta del CSN es la aplicación de la metodología ISA, especialmente adecuada para el análisis según el enfoque desarrollado en el proyecto SMAP que pretende obtener los valores best-estimate con incertidumbre de las variables de seguridad que son comparadas con los límites de seguridad, para obtener la frecuencia con la que éstos límites son superados. La ventaja que ofrece la ISA es que permite el análisis selectivo y discreto de los rangos de los parámetros inciertos que tienen mayor influencia en la superación de los límites de seguridad, o frecuencia de excedencia del límite, permitiendo así evaluar los cambios producidos por variaciones en el diseño u operación de la central que serían imperceptibles o complicados de cuantificar con otro tipo de metodologías. La ISA se engloba dentro de las metodologías de APS dinámico discreto que utilizan la generación de árboles de sucesos dinámicos (DET) y se basa en la Theory of Stimulated Dynamics (TSD), teoría de fiabilidad dinámica simplificada que permite la cuantificación del riesgo de cada una de las secuencias. Con la ISA se modelan y simulan todas las interacciones relevantes en una central: diseño, condiciones de operación, mantenimiento, actuaciones de los operadores, eventos estocásticos, etc. Por ello requiere la integración de códigos de: simulación termohidráulica y procedimientos de operación; delineación de árboles de sucesos; cuantificación de árboles de fallos y sucesos; tratamiento de incertidumbres e integración del riesgo. La tesis contiene la aplicación de la metodología ISA al análisis integrado del suceso iniciador de la pérdida del sistema de refrigeración de componentes (CCWS) que genera secuencias de pérdida de refrigerante del reactor a través de los sellos de las bombas principales del circuito de refrigerante del reactor (SLOCA). Se utiliza para probar el cambio en los márgenes, con respecto al límite de la máxima temperatura de pico de vaina (1477 K), que sería posible en virtud de un potencial aumento de potencia del 10 % en el reactor de agua a presión de la C.N. Zion. El trabajo realizado para la consecución de la tesis, fruto de la colaboración de la Escuela Técnica Superior de Ingenieros de Minas y Energía y la empresa de soluciones tecnológicas Ekergy Software S.L. (NFQ Solutions) con el área MOSI del CSN, ha sido la base para la contribución del CSN en el ejercicio SM2A. Este ejercicio ha sido utilizado como evaluación del desarrollo de algunas de las ideas, sugerencias, y los algoritmos detrás de la metodología ISA. Como resultado se ha obtenido un ligero aumento de la frecuencia de excedencia del daño (DEF) provocado por el aumento de potencia. Este resultado demuestra la viabilidad de la metodología ISA para obtener medidas de las variaciones en los márgenes de seguridad que han sido provocadas por modificaciones en la planta. También se ha mostrado que es especialmente adecuada en escenarios donde los eventos estocásticos o las actuaciones de recuperación o mitigación de los operadores pueden tener un papel relevante en el riesgo. Los resultados obtenidos no tienen validez más allá de la de mostrar la viabilidad de la metodología ISA. La central nuclear en la que se aplica el estudio está clausurada y la información relativa a sus análisis de seguridad es deficiente, por lo que han sido necesarias asunciones sin comprobación o aproximaciones basadas en estudios genéricos o de otras plantas. Se han establecido tres fases en el proceso de análisis: primero, obtención del árbol de sucesos dinámico de referencia; segundo, análisis de incertidumbres y obtención de los dominios de daño; y tercero, cuantificación del riesgo. Se han mostrado diversas aplicaciones de la metodología y ventajas que presenta frente al APS clásico. También se ha contribuido al desarrollo del prototipo de herramienta para la aplicación de la metodología ISA (SCAIS). ABSTRACT The Integrated Safety Analysis methodology (ISA), developed by the Consejo de Seguridad Nuclear (CSN), is being assessed in various applications encouraged by CSN. An Integrated Safety Analysis merges the evolved techniques of the usually applied safety analysis methodologies; deterministic and probabilistic. It is considered as a suitable tool for assessing risk in a Risk Informed Regulation framework, the approach under development that is being adopted on Nuclear Safety around the world. In this policy framework, the projects Safety Margin Action Plan (SMAP) and Safety Margin Assessment Application (SM2A), set up by the Committee on the Safety of Nuclear Installations (CSNI) of the Nuclear Energy Agency within the Organization for Economic Co-operation and Development (OECD), were aimed to obtain a methodology and its application for the integration of risk and safety margins in the assessment of the changes to the overall safety as a result of changes in the nuclear plant condition. The committee provides a forum for the exchange of technical information and cooperation among member organizations which contribute their respective approaches in research, development and engineering. The ISA methodology, proposed by CSN, specially fits with the SMAP approach that aims at obtaining Best Estimate Plus Uncertainty values of the safety variables to be compared with the safety limits. This makes it possible to obtain the exceedance frequencies of the safety limit. The ISA has the advantage over other methods of allowing the specific and discrete evaluation of the most influential uncertain parameters in the limit exceedance frequency. In this way the changes due to design or operation variation, imperceptibles or complicated to by quantified by other methods, are correctly evaluated. The ISA methodology is one of the discrete methodologies of the Dynamic PSA framework that uses the generation of dynamic event trees (DET). It is based on the Theory of Stimulated Dynamics (TSD), a simplified version of the theory of Probabilistic Dynamics that allows the risk quantification. The ISA models and simulates all the important interactions in a Nuclear Power Plant; design, operating conditions, maintenance, human actuations, stochastic events, etc. In order to that, it requires the integration of codes to obtain: Thermohydraulic and human actuations; Even trees delineation; Fault Trees and Event Trees quantification; Uncertainty analysis and risk assessment. This written dissertation narrates the application of the ISA methodology to the initiating event of the Loss of the Component Cooling System (CCWS) generating sequences of loss of reactor coolant through the seals of the reactor coolant pump (SLOCA). It is used to test the change in margins with respect to the maximum clad temperature limit (1477 K) that would be possible under a potential 10 % power up-rate effected in the pressurized water reactor of Zion NPP. The work done to achieve the thesis, fruit of the collaborative agreement of the School of Mining and Energy Engineering and the company of technological solutions Ekergy Software S.L. (NFQ Solutions) with de specialized modeling and simulation branch of the CSN, has been the basis for the contribution of the CSN in the exercise SM2A. This exercise has been used as an assessment of the development of some of the ideas, suggestions, and algorithms behind the ISA methodology. It has been obtained a slight increase in the Damage Exceedance Frequency (DEF) caused by the power up-rate. This result shows that ISA methodology allows quantifying the safety margin change when design modifications are performed in a NPP and is specially suitable for scenarios where stochastic events or human responses have an important role to prevent or mitigate the accidental consequences and the total risk. The results do not have any validity out of showing the viability of the methodology ISA. Zion NPP was retired and information of its safety analysis is scarce, so assumptions without verification or approximations based on generic studies have been required. Three phases are established in the analysis process: first, obtaining the reference dynamic event tree; second, uncertainty analysis and obtaining the damage domains; third, risk quantification. There have been shown various applications of the methodology and advantages over the classical PSA. It has also contributed to the development of the prototype tool for the implementation of the ISA methodology (SCAIS).

Compatibilidad de Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) y Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), importantes enemigos naturales de la mosca blanca Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) en cultivos hortícolas, con nuevas barreras físicas selectivas y modernos plaguicidas

Los programas de Gestión Integrada de Plagas (GIP) promueven el uso de estrategias de control que sean respetuosas con el medio ambiente, sin embargo el uso de insecticidas en los cultivos hortícolas sigue siendo necesario para el control de determinadas plagas, como es el caso de la mosca blanca Bemisia tabaci (Gennadius). Por ello, el objetivo de esta tesis es el estudio de la integración de las tres estrategias de control más empleadas hoy en día para el control de plagas: el control biológico, el físico y el químico. Una primera parte de este trabajo ha consistido en el estudio de los efectos letales y subletales de once insecticidas, aplicados a la dosis máxima de campo, sobre los enemigos naturales Eretmocerus mundus Mercet y Amblyseius swirskii Athias-Henriot, mediante ensayos de laboratorio y persistencia (laboratorio extendido). Para la evaluación de la toxicidad de los insecticidas sobre los estados de vida más protegidos de estos enemigos naturales, se trataron bajo la Torre de Potter las pupas de E. mundus y los huevos de A. swirskii. Además, se llevaron a cabo ensayos de contacto residual para determinar los efectos letales y subletales de estos insecticidas sobre el estado adulto de ambas especies de enemigos naturales. Para ello, los pesticidas se aplicaron sobre placas de cristal (laboratorio) o sobre plantas (laboratorio extendido: persistencia). Los resultados mostraron que los insecticidas flonicamida, flubendiamida, metaflumizona, metoxifenocida, spiromesifen y spirotetramat eran compatibles con el estado de pupa de E. mundus (OILB 1: Inocuos). Sin embargo, abamectina, deltametrina y emamectina fueron categorizadas como ligeramente tóxicas (OILB 2) al causar efectos deletéreos. Los dos pesticidas más tóxicos fueron spinosad y sulfoxaflor, los cuales redujeron significativamente la emergencia de las pupas tratadas (OILB 4: Tóxicos). Flonicamida, flubendiamida, metoxifenocida y spiromesifen fueron compatibles con el estado adulto de E. mundus (OILB 1: Inocuos). Abamectina, deltametrina, emamectina, metaflumizona y spiromesifen pueden ser recomendados para su uso en programas de GIP, si se usan los plazos de seguridad apropiados, de acuerdo con la persistencia de cada uno de estos insecticidas, antes de la liberación del enemigo natural. Al contrario, spinosad y sulfoxaflor no resultaron ser compatibles (OILB D: Persistentes), aunque la realización de ensayos adicionales es necesaria para ver los efectos de los mismos en campo. Todos los insecticidas estudiados, excepto el spirotetramat (OILB 2: Ligeramente tóxico), fueron selectivos para el estado de huevo de A. swirskii (OILB 1: Inocuos). Flonicamida, flubendiamida, metaflumizona, metoxifenocida, spiromesifen, spirotetramat y sulfoxaflor, fueron compatibles con el estado adulto de A. swirskii (OILB 1: Inocuos). Abamectina, deltametrina, emamectina y spinosad pueden ser recomendados para su uso en programas de GIP, si se usan los plazos de seguridad apropiados, de acuerdo con la persistencia de cada uno de estos insecticidas, antes de la liberación del enemigo natural. Entre las nuevas estrategias de la GIP, los plásticos y mallas fotoselectivas han demostrado ser una herramienta importante para el control de plagas y enfermedades en cultivos hortícolas protegidos. Por ello, en una segunda parte de este trabajo, se estudiaron tanto los efectos directos, como la combinación de efectos directos y mediados por planta y plaga de ambientes pobres en luz UV, en presencia o ausencia del Virus del rizado amarillo del tomate (TYLCV), sobre E. mundus. En primer lugar, se realizó un ensayo al aire libre para la evaluación de la capacidad de vuelo de E. mundus en cajas tipo túnel (1 x 0,6 x 0,6 m) cubiertas con distintas barreras absorbentes de luz UV. Se detectó un efecto directo en la capacidad de orientación de E. mundus, debido a que este parasitoide utiliza estímulos visuales para localizar a sus huéspedes, únicamente en las barreras que bloqueaban más del 65% de la luz UV (malla G). En segundo lugar, bajo condiciones de invernadero, se evaluó la combinación de efectos directos y mediados por planta y plaga sobre E. mundus, usando plantas de tomate sanas o infectadas con el TYLCV y cajas (30 x 30 x 60 cm) cubiertas con los distintos plásticos fotoselectivos. En este caso, no se observó ningún efecto en la capacidad benéfica del parasitoide cuando este estaba en contacto con plantas de tomate infestadas con ninfas de B. tabaci, lo que demuestra que este insecto usa estímulos táctiles para encontrar a sus huéspedes a cortas distancias. Además, las diferentes condiciones de radiación UV estudiadas tuvieron cierto impacto en la morfología, fisiología y bioquímica de las plantas de tomate, infestadas o no con el virus de la cuchara, detectándose pequeñas alteraciones en alguno de los parámetros estudiados, como el peso fresco y seco, el contenido en H y el espesor de las cutículas y de las paredes celulares de la epidermis foliar. Por último, no se observaron efectos de la radiación UV mediados por planta, ni en B. tabaci ni en su parasitoide, E. mundus. En una tercera parte, se evaluaron los efectos de una malla tratada con bifentrin sobre ambos enemigos naturales, en ensayos de laboratorio, semicampo y campo. Las mallas tratadas fueron diseñadas originariamente para el control de mosquitos vectores de la malaria, y actualmente se está trabajando para su uso en agricultura, como una nueva estrategia de control de plagas. En ensayos de laboratorio, cuando adultos de E. mundus y A. swirskii se expusieron por contacto durante 72 horas con la malla tratada (cajas de 6 cm diámetro), se registró una alta mortalidad. Sin embargo, en el ensayo de preferencia, estos enemigos naturales no fueron capaces de detectar la presencia de bifentrin y, en aquellos individuos forzados a atravesar la malla tratada, no se observó mortalidad a corto plazo (72 horas). En estudios de semicampo, llevados a cabo bajo condiciones de invernadero en cajas de 25 x 25 x 60 cm de altura, la capacidad benéfica de E. mundus no se vio afectada. Finalmente, en ensayos de campo llevados a cabo en invernaderos comerciales (4000m2) en Almería, A. swirskii no se vio afectado por la presencia en el cultivo de la malla tratada con bifentrin y los niveles de infestación de B. tabaci y F. occidentalis detectados bajo dicha malla, fueron inferiores a los del control. Por último, se ha evaluado la composición de la microflora bacteriana de tres especies de parasitoides, E. mundus, Eretmocerus eremicus Rose & Zolnerowich y Encarsia formosa Gahan, y la influencia de la misma en su susceptibilidad a insecticidas. Se llevó a cabo una extracción total de ADN de los insectos y la región variable V4 del ARNr se amplificó usando cebadores universales bacterianos. Para identificar las secuencias de los géneros bacterianos presentes en los parasitoides, se realizó una Next Generation sequencing (Illumina sequencing). Una vez identificados los géneros bacterianos, el gen ADNr 16S de las Actinobacterias se amplificó del ADN extraído de los insectos, usando cebadores universales bacterianos y específicos de Actinobacterias, y los productos de la Nested PCR fueron clonados para identificar todas las especies del género Arthrobacter. Tres bacterias (A. aurescens Phillips, A. nicotinovarans Kodama, Yamamoto, Amano and Amichi y A. uratoxydans Stackebrandt, Fowler, Fiedler and Seiler), próximas a las especies de Arthrobacter presentes en los parasitoides, se obtuvieron de la colección bacteriana del BCCMTM/LMG y se midió su actividad esterasa. Finalmente, se realizaron ensayos con antibióticos (tetraciclina) y de contacto residual con insecticidas (abamectina) para determinar la influencia de las especies de Arthrobacter en la susceptibilidad de E. mundus a insecticidas. Los resultados muestran que este género bacteriano puede afectar a la toxicidad de E. mundus a abamectina, mostrando la importancia de la comunidad microbiana en enemigos naturales, factor que debe ser considerado en los estudios de evaluación de los riesgos de los insecticidas. ABSTRACT Integrated Pest Management (IPM) programs promote the use of control strategies more respectful with the environment; however the use of insecticides in vegetable crops is still needed to control certain pests, such as the whitefly Bemisia tabaci (Gennadius). Therefore, the objective of this work is to study the integration of the three most commonly used pest control strategies nowadays: biological, physical and chemical control. Firstly, the lethal and sublethal effects of eleven insecticides, applied at their maximum field recommended concentration, on the parasitic wasp Eretmocerus mundus Mercet and the predator Amblyseius swirskii Athias-Henriot has been assessed in the laboratory and in persistence tests (extended laboratory). To test the effects of pesticides on the most protected life stage of these natural enemies, E. mundus pupae and A. swirskii eggs were sprayed under a Potter precision spray tower. Laboratory contact tests were therefore conducted to determine the lethal and sublethal effects of these pesticides on the adult stage of these natural enemies. In the residual contact tests the pesticides were applied on glass plates (laboratory) or plants (extended laboratory: persistence). The study showed that the insecticides flonicamid, flubendiamide, metaflumizone, methoxyfenozide, spiromesifen and spirotetramat were selective for E. mundus pupae (IOBC 1: Harmless). Nevertheless, abamectin, deltamethrin and emamectin were categorized as slightly harmful (IOBC 2) due to the deleterious effects caused. The two most harmful pesticides were spinosad and sulfoxaflor, which significantly reduced the adult emergence from treated pupae (IOBC 4: Harmful). Flonicamid, flubendiamide, methoxyfenozide and spiromesifen were compatible with E. mundus adults (IOBC 1: Harmless). Base on the duration of the harmful activity, abamectin, deltamethrin, emamectin, metaflumizone and spirotetramat could be recommended for use in IPM programs if appropriate safety deadlines are used before the natural enemy release. On the contrary, spinosad and sulfoxaflor were not compatible (IOBC D: persistent), although additional studies are required to determine their effects under field conditions. All the pesticides tested, except spirotetramat (IOBC 2: Slightly harmful), were selective for A. swirskii eggs (IOBC 1: Harmless). Flonicamid, flubendiamide, metaflumizone, methoxyfenozide, spiromesifen, spirotetramat and sulfoxaflor were compatible with A. swirskii adults (IOBC 1: Harmless). However, abamectin, deltamethrin, emamectin and spinosad could be recommended for use in IPM programs if appropriate safety deadlines are used before the natural enemy release. Among new IPM strategies, UV-absorbing photoselective plastic films and nets have been shown to be an important tool for the control of pests and diseases in horticultural protected crops. Because of that, we secondly studied the plant and pest insect-mediated and/or the direct effects on E. mundus under different UV radiation conditions, in presence or absence of the Tomato Yellow Leaf Curl Virus (TYLCV). In the first experiment, performed outdoors, the flight activity of E. mundus was studied in one-chamber tunnels (1 x 0.6 x 0.6 m) covered with different photoselective barriers. Because E. mundus uses visual cues for host location at a long distance, a direct effect on its host location ability was detected, but only in the UV-absorbing barriers blocking more than 65% of the UV light (G net). In a second experiment, the direct and plant and pest insect-mediated effects of different UV radiation conditions on E. mundus were studied, inside cages (30 x 30 x 60 cm) covered with the different UVplastic films and under greenhouse conditions, using healthy or TYLCV-virus infected tomato plants. In this case, not any effect on the beneficial capacity of this parasitoid was detected, proving that he uses tactile cues at a short distance of the host. Moreover, the different UV radiation conditions studied had a certain direct impact in the morphology, physiology and biochemistry of tomato plants infested or not with the TYLCV, and small alterations in some parameters such as fresh and dry weight, H percentage and cuticle and cell wall thickness of epidermal cells of the leaves, were detected. Finally, none plant-mediated UV effects neither in the whitefly B. tabaci nor in their parasitic wasp were found. Thirdly, the effects of a bifenthrin treated net were evaluated in different laboratory, semi-field and field experiments on the natural enemies studied. Treated nets were developed long time ago aiming at the control of the mosquitoes vectors of malaria, and nowadays, there is a great interest on assessing the possibility of their use in agriculture. In laboratory assays, a high mortality was recorded when E. mundus and A. swirskii adults were exposed by contact to the bifenthrin treated net for 72 hours in small cages (12 cm diameter). However, these natural enemies were not able to detect the presence of bifenthrin in a dual-choice test and no short-term mortality (72 hours) was recorded in those individuals that went through the treated net. In semi-field assays, performed under greenhouse conditions with cages of 25 x 25 x 60 cm high, the beneficial capacity of E. mundus was not affected. Finally, in field assays carried out in commercial multispan greenhouses (4000 m2) in Almería, A. swirskii was not affected by the presence of the bifenthrin treated net in the crop and the B. tabaci and F. occidentalis infestation levels were significantly lower than in the control. Finally, the composition of the microflora present in three species of parasitoids, E. mundus, Eretmocerus eremicus Rose & Zolnerowich and Encarsia formosa Gahan, and its influence in their susceptibility to insecticides, have been assessed. A total DNA extraction was performed on insects and universal bacterial primers were used to amplify the variable V4 region of the rRNA. A Next Generation sequencing (Illumina sequencing) was performed to identify the sequences of the bacterial genera present in the parasitic wasps. Once, the bacterial genera were identified, 16S rDNA gene of Actinobacteria were amplified from insects DNA extracts using the universal bacterial and actinobacterial primers, and the nested PCR products, were cloned to identify the Arthrobacter species. Three bacteria (A. aurescens Phillips, A. nicotinovarans Kodama, Yamamoto, Amano and Amichi and A. uratoxydans Stackebrandt, Fowler, Fiedler and Seiler), having the closest match with the Arthrobacter species present in the parasitic wasps, were obtained from the BCCMTM/LMG bacteria collection and its esterase activity was measured. Finally, antibiotic and residual contact tests were done to determine the influence of Arthrobacter species in the susceptibility of E. mundus to pesticides (abamectin). The results suggest that this bacterial genus can affect the toxicity of E. mundus to abamectin, which in turn supports the importance of the microbial community in natural enemies that it should be considered as a factor in risk assessment tests of pesticides.

Development of an adequate model for verification of design safety-margins of the HTTR nuclear test facility

This work is based on the prototype High Engineering Test Reactor (HTTR) of the Japan Agency of Energy Atomic (JAEA). Its objective is to describe an adequate deterministic model to be used in the assessment of its design safety margins via damage domains. The concept of damage domain is defined and it is shown its relevance in the ongoing effort to apply dynamic risk assessment methods and tools based on the Theory of Stimulated Dynamics (TSD). To illustrate, we present results of an abnormal control rod (CR) withdrawal during subcritical condition and its comparison with results obtained by JAEA. No attempt is made yet to actually assess the detailed scenarios, rather to show how the approach may handle events of its kind