Amos Necci - Academia.edu (original) (raw)
Papers by Amos Necci
International Journal of Disaster Risk Reduction, 2021
Chemical engineering transactions, 2014
Quantification of Risk Reduction Due to the Installation of Different Lightning Protection Soluti... more Quantification of Risk Reduction Due to the Installation of Different Lightning Protection Solutions for Large Atmospheric Storage Tanks Amos Necci*, Giacomo Antonioni, Valerio Cozzani, Alberto Borghetti, Carlo Alberto Nucci a Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, DICAM, Alma Mater Studiorum Università di Bologna, via Terracini n.28, 40131 Bologna, Italy Dipartimento di Ingegneria dell’Energia Elettrica e dell’Informazione «Guglielmo Marconi», DEI, Alma Mater Studiorum Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy amos.necci2@unibo.it
The so called cascading events, which lead to high-impact low-frequency scenarios are rising conc... more The so called cascading events, which lead to high-impact low-frequency scenarios are rising concern worldwide. A chain of events result in a major industrial accident with dreadful (and often unpredicted) consequences. Cascading events can be the result of the realization of an external threat, like a terrorist attack a natural disaster or of “domino effect”. During domino events the escalation of a primary accident is driven by the propagation of the primary event to nearby units, causing an overall increment of the accident severity and an increment of the risk associated to an industrial installation. Also natural disasters, like intense flooding, hurricanes, earthquake and lightning are found capable to enhance the risk of an industrial area, triggering loss of containment of hazardous materials and in major accidents. The scientific community usually refers to those accidents as “NaTechs”: natural events triggering industrial accidents. In this document, a state of the art of ...
Loss Prevention Bulletin, 2017
Natural hazards can cause loss-of-containment events at hazardous installations, resulting in fir... more Natural hazards can cause loss-of-containment events at hazardous installations, resulting in fires, explosions or toxic or radioactive releases. These so-called Natech accidents have frequently had severe consequences on the population, the environment and the economy. Proper preparedness for Natech accidents is therefore crucial. Using case studies from across the world, this article highlights the unique difficulties associated with emergency preparedness and response for Natech accidents and makes recommendations on how to meet these challenges.JRC.E.2-Technology Innovation in Securit
Chemical engineering transactions, 2014
Natural events impacting on process plants may lead to severe technological accidents. These even... more Natural events impacting on process plants may lead to severe technological accidents. These events are usually defined as NaTech events (Natural Hazard Triggering Technological Disasters). In order to derive the frequencies of accident scenarios associated to NaTech events for QRA (Quantitative Risk Assessment) implementation, a critical issue is the availability of equipment vulnerability models. The aim of the present study was to present a vulnerability model for the assessment of failure probability of atmospheric vessels involved in flooding events. The vulnerability model was based both on the severity of the natural event and on the construction features of the equipment. In order to explore the model features and its potentialities, the application to case-studies was carried out analysing an actual industrial layout. The results obtained confirmed that NaTech scenarios caused by floods may have an important influence on risk assessment and management of industrial facilities.
Chemical engineering transactions, 2016
NaTech (natural-technological) events caused by the impact of floods on industrial facilities may... more NaTech (natural-technological) events caused by the impact of floods on industrial facilities may lead to major accidents following damages to structures and equipment. In this study, we explored the quantitative assessment of NaTech accidents triggered by floods. A specific methodology was developed, adopting equipment vulnerability models aimed at determining the failure frequency of equipment affected by flooding. A reference case study was analysed, taking into account a flood scenario impacting on an industrial facility. Risk results with and without flood-triggered NaTech scenarios were compared, determining the influence of NaTech scenarios on the overall risk profile.
This chapter demonstrates the detailed quantitative analysis of Natech risk by applying the ARIPA... more This chapter demonstrates the detailed quantitative analysis of Natech risk by applying the ARIPAR-GIS software introduced in Chapter 9 to two case studies. Case study 1 analyzes earthquake-induced Natech risks at a hazardous facility and case study 2 studies the impact of floods. Individual and societal risk were calculated and compared to the risk levels obtained without considering Natech scenarios. The results confirm the significant influence that Natech risks may have on the overall risk at a hazardous installation.
Safety Science, 2021
Technological accidents are a threat to the population, the environment and the economy. Occasion... more 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.
Ocean Engineering, 2019
Abstract Specific risks to offshore oil and gas operations manifest in the Arctic and other harsh... more Abstract 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.
International Journal of Disaster Risk Reduction, 2019
Industrial facilities and critical infrastructure are vulnerable to the impact of natural hazards... more 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 socioeconomic 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.
International Journal of Disaster Risk Reduction, 2019
Natural hazard impacts on industrial activities handling hazardous substances can result in sever... more 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 wellknown 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.
Reliability Engineering & System Safety, 2017
The propagation of accidents among process units may lead to severe cascading events or domino ef... more The propagation of accidents among process units may lead to severe cascading events or domino effects with catastrophic consequences. Prevention, mitigation and management of domino scenarios is of utmost importance and may be achieved in industrial facilities through the adoption of multiple safety layers. The present study was aimed at developing an innovative methodology to address the quantitative risk assessment (QRA) of domino scenarios accounting for the presence and role of safety barriers. Based on the expected performance of safety barriers, a dedicated event tree analysis allowed the identification and the assessment of the frequencies of the different end-point events deriving from unmitigated and partially mitigated domino chains. Specific criteria were introduced in consequence analysis to consider the mitigation effects of end-point scenarios deriving from safety barriers. Individual and societal risk indexes were calculated accounting for safety barriers and the mitigated scenarios that may result from their actions. The application of the methodology to case-studies of industrial interest proved the importance of introducing a specific systematic and quantitative analysis of safety barrier performance when addressing escalation leading to domino effect.
Reliability Engineering & System Safety, 2016
Lightning is one of the most frequent accident causes in storage tank parks, and accidents trigge... more Lightning is one of the most frequent accident causes in storage tank parks, and accidents triggered by lightning are the most frequent Natech event reported in past-accident analysis. In the present study, a methodology for the inclusion of accidents triggered by lightning in Quantitative Risk Assessment (QRA) was developed. A model for the assessment of lightning impact probability on process equipment and specific equipment vulnerability models were coupled to dedicated event trees, allowing the quantification of risk indexes. The methodology developed also allows the assessment of risk reduction by the implementation of different lightning protection strategies. The results obtained represent a step forward towards the introduction of risk-based design of lightning protection systems.
Safety and Reliability of Complex Engineered Systems, 2015
In recent years, severe natural events raised the concern for the so-called NaTech (natural-techn... more In recent years, severe natural events raised the concern for the so-called NaTech (natural-technological) accident scenarios: technological accidents caused by the impact of a natural event on an industrial facility or infrastructure. Severe scenarios typical of the process industry, as fires, explosions, toxic releases, and water pollution were reported as the consequence of natural events in industrial areas. The historical analysis of accidental scenarios triggered by lightning shows that the impact of a lightning on an atmospheric storage tank might be the initiating event of a severe accident. The analysis of past accident evidences that several alternative damage mechanisms and accident scenarios may follow lightning impact. Although lightning hazard is well known and is usually considered in the risk analysis of chemical and process plants, well accepted quantitative procedures to assess the contribution of accidents triggered by lightning to industrial risk are still lackin...
The historical analysis of accidental scenarios triggered by lightning shows that the impact of a... more The historical analysis of accidental scenarios triggered by lightning shows that the impact of a lightning on a process plant might be the initiating event of a severe accident. The analysis identifies the most common damages to the equipment as either immediate ignition of flammable atmospheres or structural damage with subsequent release. However, the available information on lighting damage to industrial equipment is fragmented and not very detailed. The aim of the present study is to define a failure model for reference equipment categories following lightning impact. Starting from the analysis of lightning damage, the possibility of equipment damage is assessed on the basis of lightning characteristics. The probability of failure is evaluated as the probability to find, in impacting lightning strikes, the minimum energy necessary to cause the loss of containment of the selected equipment. Probability distribution functions available for lightning characteristics, used together...
The main problem in calculating the consequences of a carbon dioxide dispersion following an acci... more The main problem in calculating the consequences of a carbon dioxide dispersion following an accidental release is the formation of solid CO2 during the expansion to ambient pressure. The dispersion models more frequently used in the framework of quantitative risk analysis, cannot describe the carbon dioxide behaviour, in particular with respect to the calculation of the rainout fraction. Moreover, only scarce data is available for two phase CO2 releases. In the present study, a specific approach was developed to calculate the particle size distribution following the release of pressurized liquid (or supercritical) CO2. The approach combines several sub-models accounting for the different mechanisms of jet break-up and specifically addresses the possible formation of solid particles. The model was validated using experimental data available for CO2 and for the release of other pressurised, superheated liquids. The model developed can find further applications in rain-out calculation...
Reliability Engineering & System Safety, 2015
High-impact low-probability (HILP) accident scenarios in industrial sites are raising a growing c... more High-impact low-probability (HILP) accident scenarios in industrial sites are raising a growing concern. Domino effect was responsible of several catastrophic accidents that affected the chemical and process industry, as well as critical infrastructures for energy as oil refineries. However, there is still a poor agreement on assessment procedures to address escalation hazard resulting in domino scenarios. The present study presents a review of the work done in the last 30 years in the field, and a critical analysis of available tools and knowledge gaps concerning domino effect assessment. The analysis of scientific publications concerning domino effect in the process industry resulted in a database of more than 60 documents, addressing three main issues: past accident analysis, models for equipment damage, risk assessment and safety management of domino scenarios. The methods, models and tools developed make now possible the quantitative assessment of domino scenarios in risk analysis and in safety management of industrial sites. Nevertheless, a number of open points still remain, where existing tools may be improved and uncertainty may be reduced.
International Journal of Disaster Risk Reduction, 2021
Chemical engineering transactions, 2014
Quantification of Risk Reduction Due to the Installation of Different Lightning Protection Soluti... more Quantification of Risk Reduction Due to the Installation of Different Lightning Protection Solutions for Large Atmospheric Storage Tanks Amos Necci*, Giacomo Antonioni, Valerio Cozzani, Alberto Borghetti, Carlo Alberto Nucci a Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, DICAM, Alma Mater Studiorum Università di Bologna, via Terracini n.28, 40131 Bologna, Italy Dipartimento di Ingegneria dell’Energia Elettrica e dell’Informazione «Guglielmo Marconi», DEI, Alma Mater Studiorum Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy amos.necci2@unibo.it
The so called cascading events, which lead to high-impact low-frequency scenarios are rising conc... more The so called cascading events, which lead to high-impact low-frequency scenarios are rising concern worldwide. A chain of events result in a major industrial accident with dreadful (and often unpredicted) consequences. Cascading events can be the result of the realization of an external threat, like a terrorist attack a natural disaster or of “domino effect”. During domino events the escalation of a primary accident is driven by the propagation of the primary event to nearby units, causing an overall increment of the accident severity and an increment of the risk associated to an industrial installation. Also natural disasters, like intense flooding, hurricanes, earthquake and lightning are found capable to enhance the risk of an industrial area, triggering loss of containment of hazardous materials and in major accidents. The scientific community usually refers to those accidents as “NaTechs”: natural events triggering industrial accidents. In this document, a state of the art of ...
Loss Prevention Bulletin, 2017
Natural hazards can cause loss-of-containment events at hazardous installations, resulting in fir... more Natural hazards can cause loss-of-containment events at hazardous installations, resulting in fires, explosions or toxic or radioactive releases. These so-called Natech accidents have frequently had severe consequences on the population, the environment and the economy. Proper preparedness for Natech accidents is therefore crucial. Using case studies from across the world, this article highlights the unique difficulties associated with emergency preparedness and response for Natech accidents and makes recommendations on how to meet these challenges.JRC.E.2-Technology Innovation in Securit
Chemical engineering transactions, 2014
Natural events impacting on process plants may lead to severe technological accidents. These even... more Natural events impacting on process plants may lead to severe technological accidents. These events are usually defined as NaTech events (Natural Hazard Triggering Technological Disasters). In order to derive the frequencies of accident scenarios associated to NaTech events for QRA (Quantitative Risk Assessment) implementation, a critical issue is the availability of equipment vulnerability models. The aim of the present study was to present a vulnerability model for the assessment of failure probability of atmospheric vessels involved in flooding events. The vulnerability model was based both on the severity of the natural event and on the construction features of the equipment. In order to explore the model features and its potentialities, the application to case-studies was carried out analysing an actual industrial layout. The results obtained confirmed that NaTech scenarios caused by floods may have an important influence on risk assessment and management of industrial facilities.
Chemical engineering transactions, 2016
NaTech (natural-technological) events caused by the impact of floods on industrial facilities may... more NaTech (natural-technological) events caused by the impact of floods on industrial facilities may lead to major accidents following damages to structures and equipment. In this study, we explored the quantitative assessment of NaTech accidents triggered by floods. A specific methodology was developed, adopting equipment vulnerability models aimed at determining the failure frequency of equipment affected by flooding. A reference case study was analysed, taking into account a flood scenario impacting on an industrial facility. Risk results with and without flood-triggered NaTech scenarios were compared, determining the influence of NaTech scenarios on the overall risk profile.
This chapter demonstrates the detailed quantitative analysis of Natech risk by applying the ARIPA... more This chapter demonstrates the detailed quantitative analysis of Natech risk by applying the ARIPAR-GIS software introduced in Chapter 9 to two case studies. Case study 1 analyzes earthquake-induced Natech risks at a hazardous facility and case study 2 studies the impact of floods. Individual and societal risk were calculated and compared to the risk levels obtained without considering Natech scenarios. The results confirm the significant influence that Natech risks may have on the overall risk at a hazardous installation.
Safety Science, 2021
Technological accidents are a threat to the population, the environment and the economy. Occasion... more 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.
Ocean Engineering, 2019
Abstract Specific risks to offshore oil and gas operations manifest in the Arctic and other harsh... more Abstract 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.
International Journal of Disaster Risk Reduction, 2019
Industrial facilities and critical infrastructure are vulnerable to the impact of natural hazards... more 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 socioeconomic 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.
International Journal of Disaster Risk Reduction, 2019
Natural hazard impacts on industrial activities handling hazardous substances can result in sever... more 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 wellknown 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.
Reliability Engineering & System Safety, 2017
The propagation of accidents among process units may lead to severe cascading events or domino ef... more The propagation of accidents among process units may lead to severe cascading events or domino effects with catastrophic consequences. Prevention, mitigation and management of domino scenarios is of utmost importance and may be achieved in industrial facilities through the adoption of multiple safety layers. The present study was aimed at developing an innovative methodology to address the quantitative risk assessment (QRA) of domino scenarios accounting for the presence and role of safety barriers. Based on the expected performance of safety barriers, a dedicated event tree analysis allowed the identification and the assessment of the frequencies of the different end-point events deriving from unmitigated and partially mitigated domino chains. Specific criteria were introduced in consequence analysis to consider the mitigation effects of end-point scenarios deriving from safety barriers. Individual and societal risk indexes were calculated accounting for safety barriers and the mitigated scenarios that may result from their actions. The application of the methodology to case-studies of industrial interest proved the importance of introducing a specific systematic and quantitative analysis of safety barrier performance when addressing escalation leading to domino effect.
Reliability Engineering & System Safety, 2016
Lightning is one of the most frequent accident causes in storage tank parks, and accidents trigge... more Lightning is one of the most frequent accident causes in storage tank parks, and accidents triggered by lightning are the most frequent Natech event reported in past-accident analysis. In the present study, a methodology for the inclusion of accidents triggered by lightning in Quantitative Risk Assessment (QRA) was developed. A model for the assessment of lightning impact probability on process equipment and specific equipment vulnerability models were coupled to dedicated event trees, allowing the quantification of risk indexes. The methodology developed also allows the assessment of risk reduction by the implementation of different lightning protection strategies. The results obtained represent a step forward towards the introduction of risk-based design of lightning protection systems.
Safety and Reliability of Complex Engineered Systems, 2015
In recent years, severe natural events raised the concern for the so-called NaTech (natural-techn... more In recent years, severe natural events raised the concern for the so-called NaTech (natural-technological) accident scenarios: technological accidents caused by the impact of a natural event on an industrial facility or infrastructure. Severe scenarios typical of the process industry, as fires, explosions, toxic releases, and water pollution were reported as the consequence of natural events in industrial areas. The historical analysis of accidental scenarios triggered by lightning shows that the impact of a lightning on an atmospheric storage tank might be the initiating event of a severe accident. The analysis of past accident evidences that several alternative damage mechanisms and accident scenarios may follow lightning impact. Although lightning hazard is well known and is usually considered in the risk analysis of chemical and process plants, well accepted quantitative procedures to assess the contribution of accidents triggered by lightning to industrial risk are still lackin...
The historical analysis of accidental scenarios triggered by lightning shows that the impact of a... more The historical analysis of accidental scenarios triggered by lightning shows that the impact of a lightning on a process plant might be the initiating event of a severe accident. The analysis identifies the most common damages to the equipment as either immediate ignition of flammable atmospheres or structural damage with subsequent release. However, the available information on lighting damage to industrial equipment is fragmented and not very detailed. The aim of the present study is to define a failure model for reference equipment categories following lightning impact. Starting from the analysis of lightning damage, the possibility of equipment damage is assessed on the basis of lightning characteristics. The probability of failure is evaluated as the probability to find, in impacting lightning strikes, the minimum energy necessary to cause the loss of containment of the selected equipment. Probability distribution functions available for lightning characteristics, used together...
The main problem in calculating the consequences of a carbon dioxide dispersion following an acci... more The main problem in calculating the consequences of a carbon dioxide dispersion following an accidental release is the formation of solid CO2 during the expansion to ambient pressure. The dispersion models more frequently used in the framework of quantitative risk analysis, cannot describe the carbon dioxide behaviour, in particular with respect to the calculation of the rainout fraction. Moreover, only scarce data is available for two phase CO2 releases. In the present study, a specific approach was developed to calculate the particle size distribution following the release of pressurized liquid (or supercritical) CO2. The approach combines several sub-models accounting for the different mechanisms of jet break-up and specifically addresses the possible formation of solid particles. The model was validated using experimental data available for CO2 and for the release of other pressurised, superheated liquids. The model developed can find further applications in rain-out calculation...
Reliability Engineering & System Safety, 2015
High-impact low-probability (HILP) accident scenarios in industrial sites are raising a growing c... more High-impact low-probability (HILP) accident scenarios in industrial sites are raising a growing concern. Domino effect was responsible of several catastrophic accidents that affected the chemical and process industry, as well as critical infrastructures for energy as oil refineries. However, there is still a poor agreement on assessment procedures to address escalation hazard resulting in domino scenarios. The present study presents a review of the work done in the last 30 years in the field, and a critical analysis of available tools and knowledge gaps concerning domino effect assessment. The analysis of scientific publications concerning domino effect in the process industry resulted in a database of more than 60 documents, addressing three main issues: past accident analysis, models for equipment damage, risk assessment and safety management of domino scenarios. The methods, models and tools developed make now possible the quantitative assessment of domino scenarios in risk analysis and in safety management of industrial sites. Nevertheless, a number of open points still remain, where existing tools may be improved and uncertainty may be reduced.