Natech Events Research Articles

Effectiveness of countermeasure options for chemical facilities against the discharge of chemical substances into rivers caused by a large earthquake: case study of the Yodo river system in Osaka prefecture, Japan

Technological accidents triggered by natural hazards, which are commonly referred to as Natech events, are rare occurrences yet carry the potential for significant damage. Specifically, the release of hazardous chemicals into the aquatic environment and community water systems poses a grave threat to human health and society. Accordingly, we must conduct assessments that consider the potential consequences of these accidents. In this study, we examined the criteria for implementing spill protection measures to mitigate river spills of chemical substances using information on the amount of chemical substances and their toxicity. The countermeasure options readily available to employees at industrial plants and chemical storage sites where a chemical spill might originate included emergency shut-off valves, bunds and related spill containment structures, and other spill prevention measures. In this case study, a combination of countermeasure options was evaluated to examine the effectiveness of spill mitigation in the Yodo River located in the Kyoto Prefecture of Japan. Results of the case study showed that bunds were emerged as the most useful countermeasure option, reducing the probability of accidents occurring and impact of accidents. We also defined a methodology for calculating the chemical storage volumes appropriate for different countermeasures to ensure that the concentration of chemicals that could reach the water intake does not exceed the standard values. We believe that these methodologies can help chemical-handling companies make decisions when countermeasure options for responding to a chemical spill into a river. Chemical-handling companies can estimate the risk to downstream water treatment plants in the chemical spill, which can also help them consider mitigation measures.

NaTech triggered by lightning: Novel insights from past events in the process industry

Lightning strikes, a prominent meteorological event, pose a significant risk of triggering technological disruptions within the process industry. To better understand this phenomenon, an analysis focused on past lightning-triggered events was carried out, examining open-source industrial-accident databases to compile a new NaTech-driven dataset of 689 records. First, an overall quantitative analysis revealed that over 80 % of these events involved incidents or loss of containment. Notably, 83.3 % of them occurred during the spring and summer, indicating a seasonal pattern. Based on the frequency of functional attributes, the chemical and petrochemical macro-sector was the most vulnerable, followed by storage and warehousing. About 40 % of all classifiable events happened on storage equipment, while 21 % happened on electric and electronic devices. Given the lack of valuable information for the principal source of data (NRC), the technological scenarios triggered were characterized using a refined subset of 127 observations, obtained considering the “other sources” of data. Fire scenarios predominated at 56 %; coincidentally, roughly 70 % of all scenarios involved hazardous substances classified as physical hazards. Estimated losses for the available information underscored the adverse consequences of lightning-triggered NaTech events, highlighting their major impact on both safety and the environment. An analysis of the event tree showed the logical path from the lightning strike to the final ignition scenarios (considering a subset of 107 records). This path accounted for 36 % of the classifiable records that directly affected the structure, while more than 50 % of them did not. Bayesian network structures made it possible to get conditional probabilities from the event tree and improved the model by adding attributes for vulnerable equipment and macro-sectors. In order to deal with the uncertain data, algorithms were used to generalize the models that were obtained from smaller subsets of data with more accurate information to the whole dataset. It provides an important additional view of unclassifiable data that otherwise remained in the dark. This novel insight contributes to increase the vulnerability awareness of industrial assets against lightning strikes.

Fragility assessment for process pipelines in flood events through physically-based hazard response analysis

Natech events triggered by floods have occurred frequently, resulting in physical damage to process equipment and subsequent releases of hazardous substances, threatening the operational safety of the process industry. Therefore, it is necessary to conduct flood fragility assessments on typical process equipment, such as storage tanks and process pipelines. Compared to storage tank, there are relatively few flood risk analysis methods applicable to process pipelines, and there is a lack of dedicated fragility models to quantify the probability of pipeline damage in flood hazard scenarios. Thus, this paper develops a process pipeline fragility model to support the quantitative risk assessment (QRA) of flood-induced Natech events more comprehensively. This model simultaneously considers the structural physical damage caused by internal pressure and external load in the pipeline and establishes the limit state equation (LSE) corresponding to the failure mode. On this basis, parametric fragility functions are trained using Monte Carlo simulations and logistic regression. A pipeline case is used to test the proposed fragility functions, and the results show that the fitted parameterized fragility model can sensitively capture changes in the failure probability curve caused by hazard intensity and pipeline characteristics changes. The proposed pipeline fragility model is applied to a composite area of pipelines and storage tanks, accurately assessing the failure probability of different types of pipelines in flood scenarios.

Chemical release risk assessment in earthquake: Natech event scenario

IntroductionIn recent decades, an increase in natural disasters has led to the Natech events occurrence, which are technological accidents triggered by natural hazards. This study aims to assess the risk of chemical release of the H2S toxic gas following an earthquake from the refinery. MethodThe Natech risk assessment was carried out in potential earthquake risk scenarios via a semi-quantitative method using Rapid-N software. The reference scenario was obtained using the Australian SMUG Model, which has presented precise prioritization. FindingsThe Natech risk assessment has shown 40 possible earthquake risk scenarios from 5 enclosing Faults in Tehran (North Tehran, Mosha, North Ray, South Ray, and Kahrizak) with an extension of more than 15 km. The earthquake moment magnitudes of 7.5, 7.1, 6.5, and 5.9 were obtained on the Richter scale and at two Focal depths of 5 and 10 km. The South-Ray Fault (HSR-1) was selected as the reference scenario with a moment magnitude of 7.5 on the Richter scale at a Focal depth of 5 km and a distance of 5.5 km from the earthquake epicenter. The highest probability of Natech risk has shown the release of H2S toxic gas in an area with a radius of 6.59 km from the studied vessel in atmospheric stability conditions. ConclusionLegislation in line with risk reduction, planning for the transfer of potentially dangerous industries to outside urban areas, monitoring land use laws, and promoting coordination between the government, industries, and people in the management of risks caused by industries containing hazardous substances and processes, assessing the risk of Natech events and their consequences, strengthening risk communication and the installation of early warning systems, and public education to adopt personal and socially safe behaviors when facing natural disasters are recommended.

Agent-based modeling methodology and temporal simulation for Natech events in chemical clusters

In chemical clusters, technological accidents triggered by natural events (Natech events) can lead to the failure of large number of units and cause catastrophic consequences. Previous studies on Natech events give primary concerns on the static analysis at small-scale region with few thoughts the impact of various safety barriers. From the perspective of the large-scale region and temporal characteristics, an agent-based modeling methodology is proposed to present the dynamic evolution process. All the units associated with the evolution are divided into natural hazard agent, hazard-affected facility agent, safety barrier agent, and escalation factor agent to reduce the computational complexity. The time-dependent state transition mechanism of each agent is analyzed to represent the evolution process, simultaneously, the temporal effect of natural hazards, safety barrier and multi escalation factors is considered by utilization of time steps. Moreover, Monte Carlo simulation is adopted to quantify the uncertainties accompanying an accident evolution. The proposed methodology is demonstrated on a complex chemical system in the large-scale region. The results of simulation show that the number of failed hazard-affected facilities in the Natech events scenario will cyclically increase and keep constant, with strong temporal characteristic. The intensity of natural hazards and the probability of failure of safety barriers make a big impact on the temporal characteristic. The results are valuable to support natural hazard prevention in chemical cluster.

Emergency response in cascading scenarios triggered by natural events

Emergency response is a procedural safety barrier of paramount importance for the mitigation of fire scenarios and the prevention of escalation. However, in Natech scenarios, emergency response may be affected by the natural event impacting the site. Indeed, when contrasting Natech accidents, emergency responders have to face both the natural event and the cascading technological scenario. Despite the criticality of the issue, limited attention was devoted to date to the analysis of emergency response in cascading sequences triggered by natural events. The present study provides a novel and technically sound methodology to assess the performance of emergency response and the required intervention time in Natech scenarios. An expert survey combined with a Bayesian Network model was used to assess the performance of the emergency response. The routing and setup phases were identified as those mostly affected by natural events. Monte Carlo simulations were used to obtain baseline data and specific probability distributions for the time required to carry out the emergency response considering the factors that may hinder the response during natural events. In Natech accidents, the time for effective mitigation resulted higher of at least a factor 2 with respect to that expected in the case of conventional accidents. The methodology developed may be used to support the improvement of the emergency management of Natech scenarios, allowing for a detailed definition of site-specific emergency response plans. Moreover, the results may be used to provide a more accurate assessment of the fire-driven escalation probability in Natech events.

The exposure of vulnerable coastal populations to flood-induced Natech events in Hampton Roads, Virginia

The exposure of vulnerable coastal populations to flood-induced Natech events in Hampton Roads, Virginia

A review on Quantitative Risk Assessments for Oil and Gas installations and changes in Risk Evaluation Techniques

Oil and gas processing plants are prone to fires, explosions, and loss of containments, gas releases leading to fatalities. Risk management systems must identify, analyze, and control hazards during facility design, construction, and operation. Risk management follows a systematic approach which is based on lesson learned from past incidents and regulatory rules are continually produced, restructured, or amended. The oil and gas sector uses Quantitative Risk Assessment (QRA) for safety during design, construction, and operation. The objective of this paper is to provide an overview for the general principles and guidelines of risk management system in oil and gas projects. A comparative analysis of Individual risk (IR) criteria and Societal Risk (SR) criteria used by several countries as a measure of tolerable risk. The paper also discusses the future trends in QRA assessment techniques like new methods adopted for integrations of the traditional QRA techniques to include 3D risk modeling through CFD, addition of escalation analysis into risk assessments from domino effects and the recent work towards inclusion of Natech events as part of QRAs.

Understanding the patterns and characteristics of Natech events in China

With the frequent occurrence of natural disasters, natural hazard triggered technological accident (Natech) risk has attracted extensive attention from academia and industry. Natech events have the characteristics of various inducements and consequences, cascading chain reactions, and complex spatial interleaving, which leads to serious consequences. The Natech event is constantly threatening China's industrial safety production. However, the systematic analysis of Natech events in China is still lacking. The study counted 288 cases in the past 20 years and constructed Natech databases. Based on the theory of risk chain and risk system, a systematic horizontal and vertical analysis was developed for the first time. It aims to understand the characteristics of Natech events in terms of temporal and spatial, hazard factors, industry and risk material, consequences and hazard. In the results, Natech events showed a fluctuating trend. The southwest region (28.13%) and the middle Yellow River region (21.18%) belong to the critical control areas. China's industries were seriously affected by the disasters of meteorological (43.75%) and secondary, especially in the Chemical & Petrochemical and manufacturing. 64.58% of Natech events caused environmental pollution, and 13.19% of Natech events caused major or above consequences. Oil (31.25%) and hazardous chemicals (28.47%) were the main substances causing pollution, fire and explosion, which need to be controlled. The research preliminarily clarifies the risk chain and characteristics of Natech events, which provided the basis for Natech risk assessment.

A Quantitative Framework for Propagation Paths of Natech Domino Effects in Chemical Industrial Parks: Part I—Failure Analysis

Along with global climate change and industrialization, domino effects caused by Natech events occurred frequently in chemical industrial parks over the past decades. Previous research has not yet proposed a reliable method to obtain all possible paths of Natech domino effects, and moreover, a risk assessment and mitigation system has not been established. The present work aims to develop a quantitative framework for propagation paths of Natech domino effects, which can effectively safeguard the sustainable development of chemical industrial parks. The presentation of this work is divided into two parts: Part I (current paper) proposes a path probability calculation method that can simultaneously consider multiple primary accident scenarios and multi-level domino effects triggered by natural disasters. The proposed method transforms the propagation paths of domino effects into the paths of directed graph by constructing the equipment failure state transition matrix and the equipment failure state transition probability matrix. The depth-first traversal algorithm is used to obtain all possible propagation paths and their propagation probabilities, providing data support for the quantitative risk assessment and prevention and control measures presented in the accompanying paper (Part II). The case study shows that the probability of equipment failure caused by multi-level domino effects triggered by Natech accidents is higher than that of conventional accidents. However, the present work only considers the spatial propagation of domino effects, while their spatio-temporal propagation remains as a further direction for this area of inquiry.

A Quantitative Framework for Propagation Paths of Natech Domino Effects in Chemical Industrial Parks: Part II—Risk Assessment and Mitigation System

This is the second part of the quantitative framework for the propagation paths of Natech domino effects in chemical industrial parks, which focuses on risk assessment and a mitigation system based on the propagation path probabilities obtained from Part I. In this paper, the risk assessment model for the propagation paths of the domino effects induced by natural disasters are developed, and the risk level is quantitatively analyzed using individual risk and social risk indexes and compared with the risk acceptance standard to determine whether the risk in the plant area is at the risk acceptance level. Furthermore, the chain-cutting disaster mitigation model for domino effects induced by Natech events and the full-life-cycle mitigation system are proposed, and the effectiveness of mitigation measures is also evaluated. The case analysis results show that Natech events and multi-level domino effects can increase the risk to an unacceptable level, and taking corresponding mitigation measures could reduce the risk to an acceptable level.

Methodology for Natech coupling risk assessment using correlative multi-criteria decision-making method

When a natural disaster occurs, it may damage multiple industrial facilities in a certain area at the same time, and the resulting Natech events may have an impact on the surrounding industrial facilities, generating coupling risk. In this study, the assessment of Natech events coupling risk is conducted using the method of correlated multi-criteria decision-making, and the knowledge of fuzzy measures is introduced to solve the uncertainty problem in Natech coupling risk. Natech Coupling Risk Index is constructed to involve physical and functional facilities. The concept of equivalent population is proposed to compare the risks generated by physical facilities and functional facilities. And economic indicators are added to calculate the comprehensive risk value. The purpose of this contribution is to enable local government managers to use their expertise and resources and the existing risk assessment of the plants themselves and rely on the scoring of experts limitedly to quickly and easily identify potential high Natech risk areas. In the calculation process of coupling risk, the government can also take the lead to promote information communication between different plants and other industrial subjects. The proposed method was applied in a realistic chemical industry area in Guangzhou, China and in a hypothetical town. The result shows that the physical risk may be transferred to the population and economy through the coupling between industrial facilities and the functional link between functional facilities and population and economy.

The Effect of Safety Barrier Degradation on the Severity of Primary Natech Scenarios

The impact of natural events on technological infrastructures may lead to severe accident scenarios involving hazardous materials, generating the so-called Natech events. This typology of accidents is particularly critical since, besides damaging process or storage equipment items, natural hazards might concurrently impair safety barriers implemented to prevent and mitigate technological scenarios, reducing the overall safety of the system and increasing the likelihood of unmitigated outcomes and domino effects. In this study, a novel methodology to perform the quantitative risk assessment of the primary Natech scenarios directly caused by the impact of natural hazards considering the presence of safety barriers with depleted performance is proposed. A multi-level approach is tailored to assess the performance modification of safety systems designed to mitigate the primary technological scenarios. An innovative procedure for the quantitative assessment of these scenarios is proposed to enable the characterization of the final outcomes considered in the quantitative risk assessment accounting for depleted barrier performance. A case study is developed to demonstrate the application of the methodology, evidencing a relevant increase in risk compared to that assessed considering the baseline performance of safety systems. The proposed methodology thus enables a more comprehensive assessment of the final outcomes of primary Natech events, fostering the development of a holistic framework for Natech quantitative risk assessment.

Natech accidents triggered by cold waves

Natural events are a widely recognized hazard for industrial sites where relevant quantities of hazardous substances are handled, due to the possible generation of cascading events resulting in severe technological accidents (Natech scenarios). To date, research efforts were mainly dedicated to the study of Natech scenarios triggered by earthquakes, floods, and hurricanes. However, a number of recent events evidenced the potential hazard of Natech scenarios triggered by cold waves and winter storms. The present study aims at providing a comprehensive analysis of past accidents involving hazardous substances triggered by cold waves affecting the industrial infrastructure. A dataset of over 740 Natech events was collected from specialized sources. A detailed analysis of the primary events and damage modes of the equipment items involved was carried out, highlighting that most of the accidents were linked to the phase transition from the liquid to the solid state of the process fluid or of atmospheric water. The analysis of the events allowed the identification of several aspects of the cause-consequence chains, such as the technological scenarios and the equipment items more frequently involved. A specific focus was also on the vulnerability and failure modes of safety barriers. The lessons learned derived from the analysis of the accidents provide key elements to prevent similar accidents from happening in the future. These were used to suggest specific safety barriers integrating winterization and freeze protection programs.

An innovative framework for risk assessment of non-structural components for industrial plants

Na-Tech events (Natural Hazard Triggering Technological Disasters) are industrial accidents triggered by natural events such as hurricanes, floods, earthquakes, tsunami, etc. In the recent decades, various analytical approaches for the performance-based earthquake engineering (PBEE) have been developed. The most famous approach has been provided by the Pacific Earthquake Engineering Research (PEER) Center, which consists of four stages: hazard analysis, demand analysis, damage analysis, and risk assessment. The accuracy of this method in the case of complex critical infrastructure, such as nuclear and non-nuclear industrial plants, is still under investigation. Specifically for these critical structures, it is necessary to define different Limit States and appropriate Engineering Demand Parameters (EDP), especially in presence of critical Non-Structural Components (NSC), whose damage can have serious consequences. Furthermore, because of the narrow distribution of frequencies in the demand of NSC, the selection of ground motion records for fragility analysis is also a critical aspect. Consequently, the aim of the proposed study is to investigate the suitability of the PBEE approach in presence of NSCs and their dynamic interaction with the primary structure. On these premises, a comprehensive shake table test campaign was carried out with the aim to investigate the seismic behaviour of two structural configurations of a representative industrial multi-storey frame equipped with process NSCs. The main limit states for NCSs are identified and the related fragility curves are built, in a PBEE perspective, based on both experimental results and finite element model (FEM) simulations. For this purpose, an innovative algorithm for ground accelerogram selection is used. Finally, the mean annual frequency (MAF) of exceedance of the experimentally identified limit states for relevant NSCs is carried out.

Spherical Fuzzy Multi-Criteria Decision-Making Approach for Risk Assessment of Natech

It is possible for a natural catastrophe to cause harm to numerous industrial facilities in the same region simultaneously. The natural catastrophe's Natech events may then affect the industrial facilities that are located nearby, so creating a coupling risk. The evaluation of the danger of Natech events coupling is conducted using the technique of multi-criteria decision-making (MCDM) methodology in this investigation. Additionally, the concept of spherical fuzzy is presented as a means of resolving the issue of ambiguity associated with the Natech coupling risk. The Natech Coupling Hazard Index is designed to include both tangible and operational resources in its calculations. The idea of an equal population is being floated as a means of contrasting the dangers presented by physical facilities with those posed by functional amenities. The spherical fuzzy set is an effective method for coping with ambiguity since it presents a broader decision-making region and identifies reluctance. under this paper, a fuzzy MDCM technique using spherical fuzzy AHP is proposed as a solution to the challenge of managing the selection of process mining methods under settings that are unclear and vague. The AHP method is used to compute the weights of criteria and shows the rank and order of alternatives. The application is performed in steps of the spherical fuzzy AHP method.

Smart approach to integrated seismic risk management in major hazard industrial plants

Past and recent events outlined the relevance of the interactions between industrial and natural hazards (NaTech) particularly for what concerns seismic risk. EU regulation, namely Directive 2012/18/EU, explicitly requires risk analysis for NaTech events. The implementation of smart technologies (sensors, actuators, innovative systems for seismic protection) to the critical elements allows for a relevant reduction of major hazards and related consequences. The “smart” application of NaTech management technologies, from early warning to active protection, allows to upgrade the safety conditions of existing industrial plants implemented as a retrofit solution, avoiding heavy and expensive structural actions During an earthquake, damages to structural and non-structural elements can occur, and the non-structural elements are often the most involved in major accidents. In order to mitigate the consequences of a major accident, a monitoring system for management of the seismic risk can be installed, integrating new dedicated sensors into the existing monitoring network. The fiber optic sensors FBG (Fiber Bragg Grating) and FSI (Fiber Segment Interferometry) are a robust, multifunctional and removable alternative to the sensors already in use in the industrial field. Furthermore, taking into account that the earthquake affects the entire plant and the safety systems (as extinguishing water supply and power lines) at the same time, smart technologies allow the simultaneous monitoring and control toward seismic events. Hence, it is evident that smart technologies can play a relevant role in NaTech management. Systems like EW and Active protection systems can be effectively used to reduce the NaTech risk and therefore to improve the resilience of a major hazard industrial plant. The object of this paper is to provide a clear descriptive overview of the implementation of smart technologies (sensors, actuators, innovative systems for seismic protection) for a relevant reduction of major hazards and related consequences.

Resilience assessment of chemical industrial areas during Natech-related cascading multi-hazards

In chemical industrial areas, technological accidents triggered by natural events (Natech events) may escalate. Complex cascading multi-hazard scenarios with high uncertainties may be caused. Resilience is an essential property of a system to withstand and recover from disruptive events. The present study focuses on the change of the resilience level due to (possible) interactions between cascading hazards, chemical installations and safety barriers during the dynamic evolution of fire escalations triggered by a natural hazard (certain cascading multi-hazard scenarios). A quantitative resilience assessment method is developed to this end. The state transition of a system facing accidents in the context of resilience is explored. Moreover, the uncertainties accompanying an accident evolution are quantified using a Dynamic Bayesian Network, allowing a detailed analysis of the system performance in different time steps. System resilience is measured as a time-dependent function with respect to the change of system performance. The applicability of the proposed methodology is demonstrated by a case study, and the effects of different configurations of safety barriers on improving resilience are discussed. The results are valuable to support disaster prevention within chemical industrial areas.

Research on three-dimensional visualization system of Natech events triggered domino accidents in oil-gas depots

Natech events and domino accidents happen worldwide and usually lead to severe consequences, especially in hazardous areas such as Oil-Gas depots. With the continuous development of the Oil-Gas industry and information technology, it is essential to realize the three-dimensional management and monitoring of hazardous substances. To evaluate the consequences caused by Natech events triggered domino accidents (accident chain), a matrix loop method was proposed to calculate the probability and evolution path of the accident chain. The actual layout and the real-time data of the Oil-Gas depot are input into the evaluation method in matrices, thus making the results reliable and updated. Besides, a B/S architecture system is developed to present the evaluation consequences of the proposed method. The three-dimensional visualization effects of natural disasters, technological accidents and the dynamic propagation process of the accident chain are also realized in the system to enhance the user's experience. A system application regarding lightning-triggered domino accidents was carried out to demonstrate the feasibility and rapidity of the proposed evaluation method and perform the system's operation process and visualization effects. The application results show that the system can provide effective decision-making assistance to safety management workers before the accident and guidance for emergency rescue operations during the accident.

Assessment of Failure Frequencies of Pipelines in Natech Events Triggered by Earthquakes

Assessment of Failure Frequencies of Pipelines in Natech Events Triggered by Earthquakes