Domino Scenarios Research Articles

Time-dependent earthquake-fire coupling fragility analysis under limited prior knowledge: A perspective from type-2 fuzzy probability

Earthquake-triggered fire domino scenarios (E-FDSs) arise frequently from the interaction between earthquakes and chemical installations, resulting in catastrophic multi-hazard coupling events. The complicated mutually amplified phenomena between natural disasters and chemical accidents significantly aggravates the escalation of domino accidents, which has posed great challenges for modeling and preventing E-FDSs. Under this impetus, this work proposes an advanced type-2 fuzzy probabilistic methodology to obtain the time-dependent failure probability of steel cylindrical tanks (SCTs) subjected to the earthquake-fire sequence. To cope with the limited prior knowledge on E-FDSs, a basic universal is established to describe the fire resistance attenuation caused by the seismic damage. The coupling failure criterion of SCTs is formulated by a type-2 fuzzy time-dependent limit state equation. A credibility-based stochastic simulation algorithm is developed for the hybrid uncertainty analysis (combining ambiguity and stochasticity). The proposed methodology is validated by case studies of a 5000 m3 fixed roof tank. Compared to the existing accident probability model, the proposed methodology can not only capture the fire resistance attenuation caused by the seismic damage but also provide a dynamic estimation of tank failure probability with respect to the fire exposure time. The proposed methodology can effectively and dynamically capture the accident evolution process, which in turn helps mitigate and prevent the spatiotemporal propagation of domino effects.

A quantitative risk assessment framework for domino accidents caused by double pool fires

Fires spreading at limited distances one to the other can cause changes in burning rates and flame shapes due to synergistic effects. These may result in more severe consequences and in the generation of specific and more intense escalation vectors, causing a higher probability of domino scenarios. In this study, a specific approach was developed to consider synergistic effects of double pool fires in a quantitative risk assessment (QRA) framework aiming at the assessment of domino accident scenarios. The double pool fire synergy (DPFS) model developed was validated against experimental results obtained using different fuels. A comprehensive framework was developed to address the quantitative risk assessment of escalation leading to domino scenarios, combining the DPFS model, escalation probability estimation for domino accident, and Bayesian network analysis. Three case studies were carried out to analyze the impact of synergistic effects on escalation probability. The results show that synergistic effect of simultaneous multiple pool fires significantly increase the intensity of the escalation vector, and the escalation probability increases up to three orders of magnitude. Furthermore, the inclusion of synergistic effect in the analysis of posterior probability improves the accuracy of identifying the critical units in domino scenarios, contributing to a better selection of the emergency response targets.

Quantitative assessment of domino effect and escalation scenarios caused by fragment projection

Fragment projection from equipment failure has been extensively recognized as a cause of cascading events and of severe domino scenarios. In recent years several mathematical models suitable for the quantitative assessment of risk due to domino effects and cascading events were developed and validated, but a systematic methodology for quantitative risk assessment caused by fragment projection and impact is still missing. In the present study, a step-by-step approach is proposed for the assessment of domino risk indices due to fragment projection. The approach builds on available sub-models for the quantitative assessment of fragment generation, impact and damage probabilities. Altogether, the proposed model supports a quantification of the risk due to escalation triggered by fragment impact that can be easily automated and integrated in risk assessment studies.

Agent-based model and simulation of mitigated domino scenarios in chemical tank farms

The growing trend of interconnecting two or more chemical process or storage facilities represents a critical safety issue, since an accident can easily escalate from an industrial establishment to the nearby plants resulting in a domino effect. However, common safety analyses often ignore cascading events in chemical tank farms, their complex and transient evolution, and mitigation effects of add-on safety measures. The aim of the present work is to develop a structured approach for the assessment of complex domino events accounting for the influence of safety barriers. The approach is based on the adoption of Agent-based Model and Simulation for the assessment of Domino effect in presence of add-on Protections (DAMS-P). For the first time, the assessment of mitigated cascading events in chemical tank farms is carried out accounting for the transient evolution of multiple scenarios and related synergistic effects, and the effect of safety barriers and their possible time-dependent degradation. A verification of DAMS-P is firstly performed through the comparison against analytic probability evaluation based on event tree analysis and tested through the application of industrial cases. The results obtained constitute a useful support for decision-making and for the identification of critical barriers and their performance evaluation.

Methodology for quantitative risk analysis of domino effects triggered by flood

Flood events impose great distress on chemical industrial areas, since they may cause Natech accidents involving multiple units. Furthermore, escalation vectors exerted by major accidents can trigger knock-on events, so-called domino effects, causing very severe consequences. In the present study, a methodology is proposed to include domino effects triggered by floods in a quantitative risk assessment, by addressing the frequency assessment of flood-induced domino scenarios. A comprehensive procedure is developed, combining the fragility model for unit damage due to floods, probability estimation for domino escalation, and combinatorial analysis for overall scenarios. Moreover, the flow interference due to the layout of chemical industrial areas is explored to calculate the damage probability more accurately. The methodology has been demonstrated by a case study, the changes in risk indexes and damage zones due to Natech domino effects are discussed. The results show that the overall risk significantly increases with respect to conventional scenarios when considering flood-induced Natech events and domino effects, evidencing the importance of risk analysis of Natech-related domino effects. Finally, some prevention measures have been proposed for chemical industrial areas to make them more resilient and safer when it comes to floods.

Assessment of safety barrier performance in the mitigation of domino scenarios caused by Natech events

Technological accidents triggered by natural hazards (Natech accidents) are likely to escalate in cascading scenarios with severe consequences. Indeed, safety barriers implemented in process plants to prevent and mitigate accidents may be affected by natural hazards as well. The present study proposes a novel comprehensive method to assess safety barriers and protection systems performance modification during natural hazards, as well as the resulting modification in the expected frequency of secondary technological scenarios that may arise. In particular, the probability and frequency of domino scenarios initiated by Natech events are assessed considering the possible concurrent degradation of safety barrier performance in case of floods and earthquakes. An approach based on layer of protection analysis is adopted to quantify safety barrier performance degradation, accounting for the modification of barrier availability and effectiveness. A dedicated event tree analysis is applied to domino effect assessment and quantification of overall escalation scenarios. The results obtained allowed a detailed assessment of the expected frequency of secondary mitigated escalation scenarios, considering the possible effect of barriers degradation within Natech events.

Quantitative risk assessment of domino effect in Natech scenarios triggered by lightning

Lightning strike is the natural event more frequency causing Natech accidents involving atmospheric storage tanks. Despite the resulting fires have usually limited severity and only local effects, domino effect may cause the escalation of these primary events, possibly affecting nearby pressurized storages and process equipment, thus resulting in relevant increase in the potential area impacted. A methodology was developed for the quantitative assessment of risk due to domino effects caused by Natech accidents triggered by lightning. A comprehensive procedure was obtained, tailoring lightning risk assessment to include probabilistic models for domino escalation based on probit approach and combinatorial analysis. The methodology was applied to a case-study to evidence the shift in risk figures due to domino effect and the credibility of the secondary domino scenarios. The results of the case-study show that an increase up to two orders of magnitude with respect to risk calculated for conventional scenarios is possible when considering lightning-induced Natech primary scenarios and their escalation.

How to address model uncertainty in the escalation of domino effects?

Modeling potential domino scenarios in process plants includes the prediction of the most probable sequence of events and the calculation of respective probabilities, so-called escalation probabilities, so that appropriate prevention and mitigation safety measures can be devised. Domino effect modeling, however, is very challenging mainly due to uncertainties involved in estimation of escalation probabilities (parameter uncertainty) and prediction of the sequence of events during a domino effect (model uncertainty). In the present study, a methodology based on dynamic Bayesian network is developed for identification of the most likely sequence of events in domino scenarios while accounting for model uncertainty. Verifying the accuracy of the methodology based on a comparison with previous studies, the methodology is applied to model single-primary-event and multiple-primary-event domino scenarios in process plants.

An emergency response decision matrix against terrorist attacks with improvised device in chemical clusters

Chemical industrial areas may constitute potential targets for deliberate actions by terrorists. Terrorists having sufficient knowledge of chemical process operations or plant layout may take advantage of improvised explosive devices (IEDs) to cause major events such as fire, explosion and toxic gas dispersion with cross-border consequences in chemical clusters. Thus, an efficient cluster-wise emergency plan to enhance the promptness and efficacy of responding to such attacks is crucial. In this study, the effects of blast wave caused by IEDs are assessed and its potentiality in triggering domino scenarios are analysed. A decision tree is developed to determine the emergency level of each company within the cluster based on the attack outcomes. Furthermore, an alert notification system is set based on a decision matrix. Finally, the identified emergency levels and the alert levels are presented in form of a multi-plant decision matrix. The application of the developed methodology is demonstrated in a case study.

Cost-effective fire protection of chemical plants against domino effects

The propagation of fire-induced domino effects in chemical plants largely depends on the primary fire scenario, on separation distances between the units, and on the presence of fire protection barriers. Passive and active safety barriers are widely employed to prevent or delay the initiation or propagation of domino effects. In the present study, a methodology has been developed based on Bayesian network to account for the impact of such safety barriers on the propagation of fire domino scenarios. The Bayesian network has been extended to a limited memory influence diagram in order to identify a cost-effective allocation of additional safety barriers to further mitigate the fire propagation. The application of the methodology has been demonstrated using a chemical tank farm. The results are in good agreement with the results of a graph theoretic approach developed in a previous study, proving the reliability of the developed methodology in cost-effective protection of process plants.

Risk assessment of mitigated domino scenarios in process facilities

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.

Relative risk model for assessing domino effect in chemical process industry

In the world especially in China, domino accidents lead to great losses of life and property. The frequency of one LOC, which is hard to estimate, is the key for the current methods. A new methodology called relative risk analysis is presented, which focuses on the discrepancy of potential losses between two domino scenarios. Moreover, the synergetic effects, which can lead to more serious losses, can be taken into account by this method. And the possibility of one specific complex propagation pattern is not necessary. The methodology is based on the damage map which can describe damage levels and impacted region caused by the domino accidents. It can be used to find a much safer layout for the process plants and better emergency plans.

Domino effect frequency assessment: The role of safety barriers

The present study aimed at the development of a quantitative approach for the assessment of safety barrier performance in the prevention of fire escalation leading to domino accidents. In order to obtain a synthetic evaluation of the protection barriers performance, specific key performance indicators (KPIs) were defined, incorporating the results of probabilistic assessment of barrier performance. The results confirmed the important role of safety barriers performance in controlling the expected frequency of domino scenarios. The KPI analysis allowed determining the performance of different barrier types accounting for specific site factors. The results allowed a more detailed assessment of the expected frequency of secondary mitigated and unmitigated scenarios in the assessment of risk due to domino effect.

Analysis of domino effect in the process industry using the event tree method

Domino scenarios are known to have severe consequences that need to be considered in Land-Use Planning. A domino effect can be initiated by several types of primary accidents, which are usually caused by a loss of containment (LOC). This study focuses on the development of a specific model for the assessment of domino scenarios based on event tree analysis. The model provides the identification of the event sequences and the accident scenarios following a LOC. A ranking based on the criticality of domino scenarios is also provided. An illustrative case study was used to demonstrate the procedure. The results confirmed that the proposed method is an effective decision support tool for domino effect prevention, allowing the identification of the most dangerous storage or process units with respect to domino effect scenarios.

Investigation of multiple domino scenarios caused by fragments

A model of multiple domino scenarios and the risk of the domino effect, which is a sequential chain escalating from the primary unit to the last unit, is presented in this paper. The trajectories of fragments from all units, the ground distribution of projectiles, and the risk of the sequential chain of the domino effect were calculated using Monte Carlo simulations. The results showed that the range affected by the fragments from each tank included the other tanks, meaning that fragments from one tank could hit the other tanks and cause multiple accidents, and that the sequential chain of the domino effect could indeed happen. The distributions of ground impacts showed that tank fragments were projected over long distances, up to 1200 m from the source. The spatial distribution of the kinetic energy at ground impact for tank fragments was also obtained. Moreover, the magnitudes of the probabilities of the primary, secondary, third, and fourth accidents in the domino chain were respectively about 10−7, 10−11, 10−15, and 10−19. These results showed that for neighboring domino effect units in the same accident chain, the risk of the most recent domino effect was 104 times that of the following domino effect.

Assessment of domino effect: State of the art and research Needs

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.

Quantitative assessment of safety barrier performance in the prevention of domino scenarios triggered by fire

The evolution of domino scenarios triggered by fire critically depends on the presence and the performance of safety barriers that may have the potential to prevent escalation, delaying or avoiding the heat-up of secondary targets. The aim of the present study is the quantitative assessment of safety barrier performance in preventing the escalation of fired domino scenarios. A LOPA (layer of protection analysis) based methodology, aimed at the definition and quantification of safety barrier performance in the prevention of escalation was developed. Data on the more common types of safety barriers were obtained in order to characterize the effectiveness and probability of failure on demand of relevant safety barriers. The methodology was exemplified with a case study. The results obtained define a procedure for the estimation of safety barrier performance in the prevention of fire escalation in domino scenarios.

Vulnerability of industrial facilities to attacks with improvised explosive devices aimed at triggering domino scenarios

Process- and chemical plants may constitute a critical target for a terrorist attack. In the present study, the analysis of industrial accidents induced by intentional acts of interference is carried out focusing on accident chains triggered by attacks with home-made (improvised) explosives. The effects of blast waves caused by improvised explosive devices are compared with those expected from a net equivalent charge of TNT by using a specific methodology for the assessment of stand-off distances. It is demonstrated that a home-made explosive device has a TNT efficiency comprised between 0.2 and 0.5. The model was applied to a case study, demonstrating the potentiality of improvised explosives in causing accident escalation sequences and severe effects on population and assets. The analysis of the case-study also allowed obtaining suggestions for an adequate security management.

Frequency Evaluation for Domino Scenarios Triggered by Heat Radiation Exposure

Frequency Evaluation for Domino Scenarios Triggered by Heat Radiation Exposure

Quantitative assessment of domino and NaTech scenarios in complex industrial areas

Since the late 80s the application of quantitative risk assessment to the issue of land-use planning with respect to major accident hazards emerged as a topic to be addressed within the safety assessment of chemical and process plants. However, in the case of industrial clusters or complex industrial areas specific methodologies are needed to deal with high-impact low-probability (HILP) events. In the present study, innovative methodologies developed for the quantitative assessment of risk due to domino and NaTech scenarios are presented. In recent years a set of models for the calculation of equipment damage probability were developed. A specific effort was dedicated to the improvement of models for the calculation of equipment damage probability in these accident scenarios. In the present study, the application of these models to case-studies was analyzed. The results of the improved models obtained for NaTech quantitative assessment were compared to previous results in the literature. A specific innovative approach was developed to multi-level quantitative assessment of domino scenarios, and its potential was analyzed. The results were examined also evidencing the role and the progress with respect to the pioneering work started on these topics by Franco Foraboschi.