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Specific risks to offshore oil and gas operations manifest in the Arctic and other harsh environments. Such extreme operating conditions can disrupt the offshore infrastructure and cause major accidents, posing a great challenge to operators. A thorough investigation of past incidents helps to learn lessons to ensure that a recurrence of serious accidents affecting workers and the environment can be prevented. The analysis of past incidents is divided into two parts. First, we offer a statistical analysis of offshore incidents triggered by natural events in the Arctic and in similar harsh environments. The analysis, organised by location, cause, and type of damage, failure mechanisms, and consequences, is based on data from the World Offshore Accident Database (WOAD). Second, we analyse a selection of accidents that occurred in the recent past in ice-prone seas, with particular attention to potential deficiencies in safety measures, design requirements and design methodologies, operations planning and component reliability. Based on the analysis, important lessons were identified which stress the need for further efforts to ensure the safety of workers and of assets and to get all actors involved in offshore operations engaged towards achieving a safer future for the exploitation of oil and gas resources.

Tsunami hazard can be analyzed from both deterministic and probabilistic points of view. The deterministic approach is based on a “credible” worst case tsunami, which is often selected from historical events in the region of study. Within the probabilistic approach (PTHA, Probabilistic Tsunami Hazard Analysis), statistical analysis can be carried out in particular regions where historical records of tsunami heights and runup are available. In areas where these historical records are scarce, synthetic series of events are usually generated using Monte Carlo approaches. Commonly, the sea level variation and the currents forced by the tidal motion are either disregarded or considered and treated as aleatory uncertainties in the numerical models. However, in zones with a macro and meso tidal regime, the effect of the tides on the probability distribution of tsunami hazard can be highly important. In this work, we present a PTHA methodology based on the generation of synthetic seismic catalogs and the incorporation of the sea level variation into a Monte Carlo simulation. We applied this methodology to the Bay of Cádiz area in Spain, a zone that was greatly damaged by the 1755 earthquake and tsunami. We build a database of tsunami numerical simulations for different variables: faults, earthquake magnitudes, epicenter locations and sea levels. From this database we generate a set of scenarios from the synthetic seismic catalogs and tidal conditions based on the probabilistic distribution of the involved variables. These scenarios cover the entire range of possible tsunami events in the synthetic catalog (earthquakes and sea levels). Each tsunami scenario is propagated using the tsunami numerical model C3, from the source region to the target coast (Cádiz Bay). Finally, we map the maximum values for a given probability of the selected variables (tsunami intensity measures) producing a set of thematic hazard maps. 1000 different time series of combined tsunamigenic earthquakes and tidal levels were synthetically generated using the Monte Carlo technique. Each time series had a 10000-year duration. The tsunami characteristics were statistically analyzed to derive different thematic maps for the return periods of 500, 1000, 5000, and 10000 years, including the maximum wave elevation, the maximum current speed, the maximum Froude number, and the maximum total forces.

Natural hazard triggered technological accidents (known as Natechs) are a subject of increasing concern due to the growing exposure of highly industrialized and urbanized areas to natural hazards. The increasing trend of such accidents along with their potentially devastating consequences has led to growing awareness and international efforts aimed at reducing Natech risk. However, despite the growing interest and increasing awareness, there is still a low level of preparedness for Natech events and there are limited contributions regarding the industry’s Natech resilience. Addressing Natech risk effectively requires a paradigm shift in the scope of analysis of these hazards beyond industrial facilities’ fence lines from both a proactive and reactive perspective, and considering area-wide implications. In this chapter, we discuss the concept of resilience engineering (RE) as it is applied to the process industries (industrial installations, such as the oil, petrochemical, and chemical industries, that produce, handle, and use large volumes of hazardous materials), the evolution of RE over time, and the existing gaps for Natech resilience. We then propose a comprehensive framework for Natech resilient industries that contemplates the interaction in a territory between the technical and organizational systems, risk governance, risk communication, and stakeholder participation.

The purpose of this study is to review and present the contribution of the Joint Research Centre of the European Commission to the development of a new methodological approach for measuring the effective capacity of national programmes aimed at reducing the risk of chemical accidents. This new methodology is specifically intended to enable comprehensive assessment and monitoring of the progress of European Union (EU) Neighbourhood Countries in building capacity to implement effective chemical accident prevention and preparedness (CAPP) programmes. The paper describes indicators developed for the EU Neighbourhood Countries project for Seveso capacity building, in which the Seveso Directive experience in the EU is the reference model for capacity building efforts and measuring progress. Measurement of key programme elements, implementing practices, competences, and resources was operationalized into a broader survey of the national chemical accident risk reduction programmes and strategies. The responses to selected questions were then aggregated into three capacity building indices. This innovative approach illustrates how the specific indices may be applied to measure progress, benchmark against other countries and identify trends in capacity building growth. Implications and benefits of the capacity building indices are discussed in terms of their relevance as leading indicators in developing capacity building strategies in specific countries and regions. It is noted that the same framework can also be used to measure capacity building towards other sustainability goals, based on specific data availabilities.

Technological accidents are a threat to the population, the environment and the economy. Occasionally, the notion of “Black Swan” event is applied to such accidents as an explanation for why they could not be prevented. By their very nature, Black Swans are considered extreme outliers which are impossible to anticipate or manage. However, technological accidents are generally foreseeable and therefore preventable when the associated risk is managed responsibly and when warning signs are not ignored. Consequently, such accidents cannot be considered Black Swans. We contend that the same holds for technological accidents triggered by natural hazards (so-called Natech accidents) which usually result from a lack of corporate oversight and insufficient application of state-of-the-art knowledge in managing the associated risk. We argue that the successful reduction of Natech risk requires a corporate mindfulness of the risk and the need to address it using updated approaches, the recognition that organizational behavior influences the risk significantly, and risk ownership that departs from the “Act-of-God” mindset which much of the discussion around natural hazards is fraught with. The study also highlights the importance of scientific research and knowledge management to reduce risks.

The Global Alliance of Disaster Research Institutes held its 3rd Global Summit of Research Institutes for Disaster Risk Reduction at the Disaster Prevention Research Institute, Kyoto University, Japan, 19–21 March, 2017. The Global Alliance seeks to contribute to enhancing disaster risk reduction (DRR) and disaster resilience through the collaboration of research organizations around the world. The summit aim was to expand the platform for bridging science and policy making by evaluating the evidence base needed to meet the expected outcomes and actions of the Sendai Framework for Disaster Risk Reduction 2015–2030 and its Science and Technology Roadmap. The summit reflected the international nature of collaborative research and action. A pre-conference questionnaire filled out by Global Alliance members identified 323 research projects that are indicative of current research. These were categorized to support seven parallel discussion sessions related to the Sendai Framework priorities for action. Four discussion sessions focused on research that aims to deepen the understanding of disaster risks. Three cross-cutting sessions focused on research that is aimed at the priorities for action on governance, resilience, and recovery. Discussion summaries were presented in plenary sessions in support of outcomes for widely enhancing the science and policy of DRR.

Space weather driven by solar activity can induce geomagnetic disturbances at the Earth's surface that can affect power transmission systems. Variations in the geomagnetic field result in geomagnetically induced currents that can enter the system through its grounding connections, saturate transformers and lead to system instability and possibly collapse. This study analyzes the impact of extreme space weather on the northern part of the European power transmission grid for different transformer designs to understand its vulnerability in case of an extreme event. The behavior of the system was analyzed in its operational mode during a severe geomagnetic storm, and mitigation measures, like line compensation, were also considered. These measures change the topology of the system, thus varying the path of geomagnetically induced currents and inducing a local imbalance in the voltage stability superimposed on the grid operational flow. Our analysis shows that the North European power transmission system is fairly robust against extreme space weather events. When considering transformers more vulnerable to geomagnetic storms, only few episodes of instability were found in correspondence with an existing voltage instability due to the underlying system load. The presence of mitigation measures limited the areas of the network in which bus voltage instabilities arise with respect to the system in which mitigation measures are absent.

Efforts have been launched to systematically collect and analyze information on the causes and dynamics of Natech accidents, as well as of near misses, to support scenario development and the design of better risk-mitigation options. Using postaccident analysis, conclusions can be drawn on the most common damage and failure modes and hazmat release paths, particularly vulnerable storage and process equipment types, and the hazardous materials most commonly involved in these types of accidents. This chapter gives an overview of natural-hazard specific lessons learned and also discusses features common to Natech accidents triggered by different natural hazards.

Dealing with Natech risk effectively involves a wide range of prevention and mitigation measures that can be physical or administrative in nature. A mix of both types of measures is commonly required for optimum protection. This chapter introduces selected organizational measures for Natech risk reduction.

Risk assessment is a prerequisite for understanding the Natech risk and for determining if and which prevention and preparedness measures should be implemented to reduce the risk. The analysis of multihazard risks is a highly complex task and there is no consolidated methodology for assessing the Natech risk. This chapter introduces selected qualitative and semiquantitative Natech risk-analysis methodologies, approaches, and tools of varying levels of resolution. The outcome of these methodologies can be used for evaluating the risk in accordance with the risk-acceptability criteria in place.

Structural prevention and mitigation measures can help prevent damage and hazardous-materials releases at industrial facilities, and contribute to reducing their consequences if releases do occur. This chapter introduces a selection of available structural protection measures for different types of natural hazards.

In this chapter, the rapid Natech risk analysis and mapping framework RAPID-N introduced in Chapter 8 is used to carry out a simplified Natech risk analysis for an industrial facility in Izmit Bay in Turkey that was subjected to a predicted Istanbul earthquake scenario. The results demonstrate RAPID-N’s capability to assess the earthquake impact on an industrial plant, including the simultaneous analysis of the Natech risk at several plant units.

Fires and explosions triggered by lightning strikes are among the most frequent Natech scenarios affecting the chemical and process industry. Although the lightning hazard is well known, well accepted quantitative procedures to assess the contribution of accidents caused by lightning to industrial risk are still lacking. In the present study, a quantitative methodology for the assessment of the expected frequency of lightning capture by process equipment is presented. A specific model, based on Monte Carlo simulations, was developed to assess the capture frequency of lightning for equipment with a given geometry. The model allows the assessment of lay-out effects and the reduction of the capture probability due to the presence of other structures or equipment items. The results of the Monte Carlo simulations were also used to develop a simplified cell method allowing a straightforward assessment of the lightning impact probability in a quantitative risk assessment framework. The developed approach allows an in-depth analysis of the hazard due to lightning impact by identifying equipment items with the highest expected frequency of lightning impacts in a given lay-out. The model thus supplies useful data to approach the assessment of the quantitative contribution of lightning-triggered accidents to industrial risk., JRC.G.5-Security technology assessment

Industrial facilities and critical infrastructure are vulnerable to the impact of natural hazards. These impacts can trigger so-called Natech accidents and the release of toxic substances, fires and explosions, potentially resulting in health effects, environmental pollution and economic losses. Different factors drive Natech risk, including technical issues linked to the characteristics inherent in Natech events, as well as risk governance and socio-economic challenges. This paper discusses the most important Natech risk drivers in detail, gives examples of existing instruments for Natech risk management in the European Union and at international level, and proposes a set of basic indicators to help measure a country's level of Natech risk reduction. It concludes with targeted recommendations on how to close persisting gaps related to Natech research and policy challenges.

Natural hazard impacts on industrial activities handling hazardous substances can result in severe cascading events such as fires, explosions, and toxic or radioactive releases. These so-called Natech accidents are often overlooked in regional and national disaster risk management plans. National Risk Assessment (NRA) is a well-known instrument to identify, analyse and compare a wide range of risks with potential impacts at a national extent. Increasingly complex and comprehensive NRAs are used globally for informed decision making. Although recognised as an important emerging issue, Natech risks are currently not considered systematically in NRAs. One cause for this deficiency is the lack of dedicated methodologies and guidance for Natech risk assessment within the NRA context. This study fills this gap by giving insight on how and in which setting Natech risks should be assessed in the NRAs. Following a contextual description of the Natech risk within the overall NRA process, different approaches for Natech risk assessment at the national level are discussed and differences with facility-level risk assessment are indicated. Natech-specific aspects to be considered in risk identification, risk analysis, and risk evaluation are explained in detail with examples from past accidents. Finally, research and policy challenges hampering the reliable Natech risk assessment in the NRAs are discussed. The provided information can improve the coherence and consistency of Natech-related aspects in the NRAs. As Natech risk is regarded as a typical example of multi-hazard risk, guidance on how to consider Natech risk can also support a better assessment of other cascading risks.

A changing climate and more frequent extreme weather events pose challenges to the oil and gas sector. Identifying how these changes will affect oil and gas extraction, transportation, processing, and delivery, and how these industries can adapt to or mitigate any adverse impacts will be vital to this sector’s supply security. This work presents an overview of the sector’s vulnerability to a changing climate. It addresses the potential for Natech hazards and proposes risk reduction measures, including mitigation and adaptation options. Assessment frameworks to ensure the safety of people, the environment, and investments in the oil and gas sector in the face of climate change are presented and their limitations discussed. It is argued that a comprehensive and systemic analysis framework for risk assessment is needed. The paper concludes that climate change and extreme weather events represent a real physical threat to the oil and gas sector, particularly in low-lying coastal areas and areas exposed to extreme weather events. The sector needs to take climate change seriously, assess its own vulnerability, and take appropriate measures to prevent or mitigate any potentially negative effects.

Several attempts have recently been made to identify the key indicators of community resilience and to group them into an overall resilience index. These studies support the evaluation of the effectiveness of resilience during recovery, and they also help establish a yardstick by which to monitor progress in resilience enhancement over time. We examine existing resilience indices in relation to economic principles and evaluate their potential to gauge and improve post-disaster economic recovery, with a focus on businesses. We conclude that the majority of indicators in use to date are not necessarily pertinent to measuring resilience at the micro-, meso- and macro-economic levels in the aftermath of a disaster. Contending that business behavior is the key to short-term recovery, we propose a framework for choosing appropriate short-run indicators toward the goal of developing an effective economic resilience index.

The Great East Japan earthquake and tsunami damaged or destroyed many industrial facilities housing or processing hazardous substances, such as refineries, petrochemical facilities and other types of chemical industry. This showed that also generally well prepared countries are at risk of suffering natural hazard triggered technological (Natech) accidents. An analysis of data collected from open sources and through interviews with authorities was performed to understand the main reasons for the industrial damage and downtime as well as the extent of hazardous-materials releases and the associated impact on society. The analysis of the data set confirmed the findings from other studies with respect to main damage and failure modes, as well as hazardous-materials release paths. In addition, gaps in Natech risk management were identified. Based on the data analysis and interviews lessons learned in support of a more far-reaching Natech risk management are presented.

A study was performed on the status of Natech risk reduction in Europeon Union Member States by means of a questionnaire survey. The results show that natural hazards are increasingly recognised as a possibly important external risk source for chemical facilities. The management of Natech risk is mainly addressed through the Member States’ legal framework for chemical-accident prevention whose effectiveness appears, however, inconclusive. Guidance on Natech risk reduction to support legislation is scarce and, where existing, did not always prevent Natech accidents from occurring. In fact, in over half the responding countries Natech accidents have resulted in the release of toxic substances, fires or explosions with sometimes fatalities and injuries. The natural events that triggered these accidents were not necessarily the ones believed to be of most concern in the Natech context, indicating an incongruity between accident causes and risk perception. Gaps in Natech risk reduction were recognised and are ...

Tsunamis can cause catastrophic loss of life, destruction of property, engineered structures and coastal infrastructure, and they can lead to major economic losses. Even though tsunamis are relatively rare in the Mediterranean Sea, their potential danger to cities along the Mediterranean coast cannot be neglected. In order to create awareness among the potentially affected people it is important to know the risk and vulnerability of the population and infrastructure related to a possible tsunami impact. In this work a hazard, vulnerability and risk analysis for buildings in two districts of Alexandria was carried out. Relevant input parameters were derived mainly from remote sensing and field data and were analyzed with a geographical information system (GIS). Based on historical records of past tsunamis, two inundation scenarios of 5 m and 9 m were defined and modeled applying a bath-type model. The resulting tsunami building risk zone maps showed that 12% of the buildings in El Gomrok district are at high or very high risk for the 5 m scenario, while the risk for El Montazah area is low. For the 9 m scenario, on the other hand, the majority of the buildings in both districts, 56% of El Gomrok, and 60% of El Montazah, are in the high or very high risk zone. An analysis of the building use indicated that the majority of these buildings are residential and commercial types, highlighting that the potential consequences of a tsunami could be severe. Due to the scarcity of historical data no frequency could be associated with the two selected scenarios. While both are credible we consider the 5 m scenario as possible but unlikely and the 9 m scenario as unlikely.

The threat of natural hazards impacting chemical facilities and infrastructures with the subsequent release of hazardous substances has been recognised as an emerging risk which is likely to be exacerbated by the ongoing climate change. Within the European FP7 project iNTeg-Risk, efforts are dedicated to address the problem of Natech accidents by trying to understand their underlying causes and by developing methodologies and tools to assess Natech risk. Special attention is thereby given to the risk of chemical accidents triggered by earthquakes, floods and lightning. This work outlines the ongoing efforts in the development of new concepts and tools for Natech hazard and vulnerability ranking, risk assessment, risk-based design, and emergency planning and early warning.

Natural hazards and disasters can cause major accidents in chemical and process installations. These so-called Natech accidents can result in hazardous-materials releases due to damage to process and storage units, or pipes. In order to understand the dynamics of Natech events, accidents triggered by earthquakes, floods and lightning recorded in industrial-accident databases were analysed. This allowed the identification of the most vulnerable equipment types, their modes of failure under natural-event loading, and the final accident scenarios. Moreover, lessons learned for future accident prevention and mitigation were derived. The analysis showed that pipes and storage tanks are the most vulnerable equipment for earthquakes, floods and lightning, calling for more research of equipment behaviour under natural-event loading. The damage modes and states are strongly dependent on the characteristics of the impacting natural event. Toxic dispersion, fires and explosions were observed as a consequence of all three types of analysed natural events. In the case of floods two additional scenarios were identified. These are water contamination and the formation of toxic and/or flammable vapours upon reaction of the released chemicals with the floodwaters. The overall number of recorded Natech accidents was found to range from 2 to 5% of all reported accidents in the analysed databases.

This work analyses the potential consequences of two tsunami scenarios and their impacts on an oil refinery located in Sicily. Two credible tsunamis originating in the Tyrrhenian Sea were selected based on historical data. The potential for damage and hazardous materials releases resulting from the tsunami impacts to a refinery was assessed. The results obtained by the JRC tsunami propagation and inundation code HyFlux2 indicate that in both scenarios there would be eighteen storage tanks (of 43 located within 400 m from the shoreline) at the refinery subject to flooding. Water flow velocities were found to be generally low

This study describes the results of a field trip to the area affected by the 12 May, 2008, Wenchuan earthquake to analyse its impact on industrial facilities. The damage severity correlates well with the age of the plant, with older facilities having suffered more extensive and severe damage than those built more recently according to the latest design codes. The main cause of worker death and injury was the collapse of warehouses, office and manufacturing buildings. This concerned mostly concrete structures with insufficient confinement or poor reinforcement. The falling debris resulted in equipment damage and loss, as well as pipe severing and crushing. Pipes were also severed or bent when connected tanks were displaced or buildings collapsed. Numerous hazardous-materials releases occurred with spills being the dominant accident scenario. In some sites soil–liquefaction induced damage was evident, highlighting the need to consider potential site effects when selecting the location for a facility. The impact of the Wenchuan earthquake on chemical facilities confirms the findings from other earthquakes in terms of typical Natech damage and failure modes, as well as of hazardous-materials release potential and mechanisms.

Tunnels in the trans-European road network (TEN) facilitate the transport of persons and goods on European roads. Following a series of major tunnel accidents European Union Directive 2004/54/EC was adopted to support the achievement of uniform and high tunnel safety levels. With future accident prevention and mitigation in mind and in support of the effective implementation of Article 15 on Reporting of the Directive we outline a procedure for learning lessons and discuss every step in the process with specific regard for its implications on Article 15. This includes accident investigation, reporting, data collection and analysis, learning lessons and their implementation. The realization that validated information on tunnel accidents is not easily available or accessible, or suffers from a lack of detail or accuracy fed into the development of a data-collection template. By its very nature the template development also guided the formulation of key recommendations for accident investigation and reporting as the main information source. In addition, key recommendations on data analysis, learning lessons and implementation were also made to assist the actors responsible for reporting or sharing information under the EU Directive.

Hurricane Katrina and Rita triggered numerous hazardous-materials releases from industrial facilities and storage terminals onshore, as well as from oil and gas production facilities offshore in the Gulf of Mexico. In this paper, we identify and analyze over 600 hazardous-materials releases triggered by Hurricanes Katrina and Rita from offshore platforms and pipelines. The results of the study may assist offshore industry owners/operators, government officials and policy makers by providing lessons learned and recommendations for better disaster planning for major storms and flood events.

Hurricanes Katrina and Rita hit the centre of the American petrochemical industry, shutting down eight refineries, hundreds of oil-drilling and production platforms, and many other industrial facilities. Furthermore, it triggered unprecedented numbers of hazardous-materials releases from industrial facilities and storage terminals onshore, as well as from oil and gas production facilities offshore in the Gulf of Mexico (GoM). In this paper, we analyse the damage caused by the two hurricanes on the offshore oil and gas industry. Hurricanes Katrina and Rita caused the largest number of destroyed and damaged platforms and pipelines, and the highest number of mobile offshore drilling units set adrift in the history of GoM operations. Following the hurricanes, changes have been proposed to operating and emergency procedures, maintenance requirements, and design practices including mooring practices for mobile offshore drilling units.

There is increasing evidence that natural disasters can trigger technological accidents and damage. These so-called Natech accidents can pose a significant risk to regions that are unprepared for responding to them. The European Commission’s Joint Research Centre has recognised the risk associated with Natech events and has started systematic research into Natechs and their underlying dynamics. This work investigates the risk associated with the flooding of industrial installations through an analysis of past case histories and using expert judgement. The potential impact of three levels of flood severity on selected industrial facilities storing and/or processing (eco-)toxic, flammable or explosive materials is analysed qualitatively and a scale is developed that links the flood intensity to the level of potential damage. Our analysis indicates that natural disasters have the potential for triggering hazmat releases and other types of technological accidents. Hence, natural disasters should be considered as separate accident-triggering events in the planning, design and operating stages of industrial facilities that process or store hazardous substances. Our work revealed a lack of detailed information on the occurrence of Natech events which indicates not necessarily a scarcity of Natechs but rather a lack of standardised reporting and record keeping.

In recent years, severe natural events raised concern about so-called NaTech accident scenarios: technological accidents caused by the impact of a natural event on an industrial facility or infrastructure. Lightning strikes are one of the most important triggers of NaTech scenarios. Moreover, previous studies showed that lightning strikes are among the main causes of loss of containment (LOC) of atmospheric storage vessels containing hazardous materials. Although the lightning hazard is well known, well accepted quantitative procedures to assess the contribution of accidents triggered by lightning to industrial risk are still lacking. In particular, the approaches to the assessment of lightning strike probability and to the damage caused by lightning strike are mainly qualitative or semi-quantitative and are mostly based on expert judgment. In the present study, a quantitative methodology for the assessment of the equipment damage probability due to lightning is presented. The lightning severity was quantified by means of probability distribution functions of two parameters: peak current intensity and lightning charge. Through the application of a Monte Carlo simulation the expected frequency of lightning strikes on the equipment and the equipment damage probability were determined. The results of the equipment damage model were validated by available experimental data on metal perforation in simulated lightning strikes. The results of the validated Monte Carlo simulations were fit to empirical functions obtaining a simplified model suitable for use in a quantitative risk assessment framework.

Radioiodine entering the containment from the postaccident primary circuit in vapor or gaseous form, as observed in the Phebus FPT0 and FPT1 tests, has a direct impact on the source term evaluation...

Natural hazards can be initiating events for accidents in oil and gas pipelines. Severe past incidents bear testimony to the risk associated with pipeline accidents triggered by natural hazards (natechs). Post-incident analysis is a valuable tool for better understanding the causes, dynamics and impacts of such accidents. To identify the main triggers of onshore transmission pipeline natechs in the USA, natural gas and hazardous liquid incident reports collected by the Pipeline and Hazardous Materials Safety Administration were analyzed. Potential natech incidents were identified by automated data-mining followed by expert review. The analysis covered ∼21,000 incidents, about 6% of which were identified as natechs. Geological hazards triggered 50% of the identified natechs, followed by meteorological (25%), climatic (11%), and hydrological (11%) hazards. Landslides are the main geological hazard with 43% of the incidents within the category. Among meteorological hazards, lightning is the major hazard with 36%. 84% of the hydrological hazard related natechs were found to be due to floods. Cold-related hazards make up 93% of the natechs caused by adverse climatic conditions. Some preliminary qualitative results on consequences are provided as well.Copyright © 2014 by ASME

Metallic silver and iodine form insoluble AgI in the containment sump which has a major impact on iodine volatility and hence on the source term to the environment. Resistance-in-series models are developed and validated against separate-effects tests. The reaction between I2 and Ag is limited by mass transfer in the liquid. The rate does not follow a parabolic law for the duration of the experiments. The extent of oxidation of the silver sample seems to play a decisive role for reactions with I− which proceed via a two-step process. The initial, rapid step is controlled by the reaction with the surface silver oxide with a contribution of mass transfer in the liquid. The subsequent, slow step is limited by reaction between I− and Ag+ at the solid–liquid interface. The reaction is probably negligible for pH > 7 and in the absence of oxidising conditions.

Blast waves, fires and fragment projection are by far the most common causes of escalation leading to domino accidents. The present chapter deals with less-frequent and more controversial domino scenarios: domino events due to indirect escalation and external events. Indirect causes of escalation, even if not frequent, may be extremely important since they are likely to be overlooked, in particular in complex industrial clusters. External hazard factors can also cause severe domino accidents. Natural events or intentional malicious acts of interference can escalate to cause severe domino events. The present chapter focuses on these particular causes of escalations, aiming to provide an approach for the assessment of these specific domino scenarios.

Natech accidents at industrial plants are an emerging risk with possibly serious consequences. For the mitigation of natech risk, authorities need to identify natech prone areas in a systematic manner. In order to facilitate probabilistic natech risk mapping, a unified methodology was developed that is based on the estimation of on-site natural hazard parameters, determination of damage probabilities of plant units, and assessment of probability and severity of possibly triggered natech events. The methodology was implemented as an on-line, extensible risk assessment and mapping software framework called RAPID-N, which allows rapid local and regional natech risk assessment and mapping with minimal data input. RAPID-N features an innovative data estimation framework to complete missing input data, such as on-site natural hazard parameters and plant unit characteristics. The framework is also used for damage assessment and natech consequence analysis, and allows easy modification of input parameters, dynamic generation of consequence models according to data availability, and extension of models by adding new equations or substituting existing ones with alternatives. Results are presented as summary reports and interactive risk maps, which can be used for land-use and emergency planning purposes by using scenario hazards, or for rapid natech consequence assessment following actual disasters. As proof of concept, the framework provides a custom implementation of the U.S. EPA's RMP Guidance for Offsite Consequence Analysis methodology to perform natech consequence analysis and includes comprehensive data for earthquakes. It is readily extendible to other natural hazards and more comprehensive risk assessment methods. (C) 2013 Elsevier Ltd. All rights reserved.

Tsunamis can represent a significant risk to the population and cause huge economic damage in many costal regions. In order to be able to identify risk hot spots and implement targeted risk reduction measures, decision makers need to have a clear picture of the risk situation in their countries or regions. This work reviews existing approaches for tsunami risk assessment and recommends a five-step process for assessing tsunami risk. As a case study, a qualitative risk assessment for a worst-case tsunami scenario was carried out to understand the tsunami risk to the population in Ca´diz. Moreover, a sensitivity analysis of the tsunami hazard input parameters was performed as a strong influence of the variability of the input parameters on the resultant tsunami hazard and risk zonation maps was observed. The study shows that regardless of the assumptions made a non-negligible tsunami risk to Ca´diz exists.

Industrial accidents triggered by natural events (NaTech accidents) are a significant category of industrial accidents. Several specific elements that characterize NaTech events still need to be investigated. In particular, the damage mode of equipment and the specific final scenarios that may take place in NaTech accidents are key elements for the assessment of hazard and risk due to these events. In the present study, data on 272 NaTech events triggered by floods were retrieved from some of the major industrial accident databases. Data on final scenarios highlighted the presence of specific events, as those due to substances reacting with water, and the importance of scenarios involving consequences for the environment. This is mainly due to the contamination of floodwater with the hazardous substances released. The analysis of process equipment damage modes allowed the identification of the expected release extents due to different water impact types during floods. The results obtained were used to generate substance-specific event trees for the quantitative assessment of the consequences of accidents triggered by floods.

The International Phebus Fission Product programme, initiated in 1988 and performed by the French "Institut de Radioprotection et de Sûreté Nucléaire" (IRSN), investigates through a series of in-pile integral experiments, key phenomena involved in light water reactor (LWR) severe accidents. The tests cover fuel rod degradation and the behaviour of fission products released via the primary coolant circuit into the containment building. The results of the first two tests, called FPT0 and FPT1, carried out under low pressure, in a steam rich atmosphere and using fresh fuel for FPT0 and fuel burned in a reactor at 23 GWdt-1 for FPT1, were immensely challenging, especially with regard to the iodine radiochemistry. Some of the most important observed phenomena with regard to the chemistry of iodine were indeed neither predicted nor pre-calculated, which clearly shows the interest and the need for carrying out integral experiments to study the complex phenomena governing fission product behaviour in a PWR in accident conditions. The three most unexpected results in the iodine behaviour related to early detection during fuel degradation of a weak but significant fraction of volatile iodine in the containment, the key role played by silver rapidly binding iodine to form insoluble AgI in the containment sump and the importance of painted surfaces in the containment atmosphere for the formation of a large quantity of volatile organic iodides. To support the Phebus test interpretation small-scale analytical experiments and computer code analyses were carried out. The former, helping towards a better understanding of overall iodine behaviour, were used to develop or improve models while the latter mainly aimed at identifying relevant key phenomena and at modelling weaknesses. Specific efforts were devoted to exploring the potential origins of the early-detected volatile iodine in the containment building. If a clear explanation has not yet been found, the non-equilibrium chemical processes favoured in the primary coolant circuit and the early radiolytic oxidation of iodides in the condensed water films are at present the most likely explanations. Models that were modified or developed and embodied in the computer codes for organic iodide formation/destruction in the gas phase and Ag-I reactions in the sump lead, in agreement with the Phebus findings respectively to greatly enhanced organic iodide formation kinetics and long term concentration in the containment atmosphere on one hand and, in the conditions of Phebus experiments, to significantly limited molecular iodine volatilisation from the sump in so far as silver was in excess compared to iodine, on the other hand. Organic iodides then quickly gain in importance and become the predominant volatile iodine species at long term. © 2006 Elsevier B.V. All rights reserved.

The THENPHEBISP 2-year thematic network started in December 2001, and was concerned with OECD/CSNI International Standard Problem 46, itself based on the Phebus FPT1 core degradation/source term experiment. The aim was to assess the capability of computer codes to model in an integrated way the physical processes taking place during a severe accident in a pressurised water reactor, from the initial stages of core degradation, the fission product transport through the primary circuit and the behaviour of the released fission products in the containment. ISP-46, coordinated by IRSN/DRS Cadarache, attracted 33 participating organisations, from 23 countries and international bodies, who submitted 47 base case calculations and 21 best-estimate calculations, using 15 different codes. The thermal behaviour of the fuel bundle and the hydrogen production were generally well captured, and good agreement for the core final state could be obtained with a suitable choice of bulk fuel relocation temperature, however this is unlikely to be representative of all plant studies so sensitivity calculations are needed with the modelling in its current state. Total volatile fission product release was simulated, but its kinetics, and the overall modelling of semi-volatile, low-volatile and structural material release (Ag/In/Cd, Sn) needs improvement. Overall retention in the circuit is well predicted, but calculations underestimate deposits in the upper plenum and overestimate those in the steam generator, also the volatility of some elements could be better predicted. Containment thermal hydraulics and depletion rate of aerosols are well calculated, but with difficulties related to partition amongst the deposition mechanisms. Calculation of iodine chemistry in the containment turned out to be more difficult. Its quality strongly depends of the calculation of release and transport in the integral codes. The major difficulties are related to the existence of gaseous iodine in the primary circuit and to the prediction of the amount of organic iodine in the gas phase. This paper summarises the results achieved and the implications for plant calculations. © 2004 Published by Elsevier B.V. All rights reserved.