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The accidental release of toxic gases leads to fire, explosion, and acute toxicity, and may result in severe problems for people and the environment. The risk analysis of hazardous chemicals using consequence modelling is essential to improve the process reliability and safety of the liquefied petroleum gas (LPG) terminal. The previous researchers focused on single-mode failure for risk assessment. No study exists on LPG plant multimode risk analysis and threat zone prediction using machine learning. This study aims to evaluate the fire and explosion hazard potential of one of Asia's biggest LPG terminals in India. Areal locations of hazardous atmospheres (ALOHA) software simulations are used to generate threat zones for the worst scenarios. The same dataset is used to develop the artificial neural network (ANN) prediction model. The threats of flammable vapour cloud, thermal radiations from fire, and overpressure blast waves are estimated in two different weather conditions. A total of 14 LPG leak scenarios involving a 19 kg capacity cylinder, 21 tons capacity tank truck, 600 tons capacity mounded bullet, and 1350 tons capacity Horton sphere in the terminal are considered. Amongst all scenarios, the catastrophic rupture of the Horton sphere of 1350 MT capacity presented the most significant risk to life safety. Thermal flux of 37.5 kW/ m2 from flames will damage nearby structures and equipment and spread fire by the domino effect. A novel soft computing technique called a threat and risk analysis-based ANN model has been developed to predict threat zone distances for LPG leaks. Based on the significance of incidents in the LPG terminal, 160 attributes were collected for the ANN modelling. The developed ANN model predicted the threat zone distance with an accuracy of R2 value being 0.9958, and MSE being 202.9061 in testing. These results are evident in the reliability of the proposed framework for safety distance prediction. The LPG plant authorities can adopt this model to assess the safety distance from the hazardous chemical explosion based on the prior forecasted atmosphere conditions from the weather department. [ABSTRACT FROM AUTHOR]

The accidental release of toxic gases leads to fire, explosion, and acute toxicity, and may result in severe problems for people and the environment. The risk analysis of hazardous chemicals using consequence modelling is essential to improve the process reliability and safety of the liquefied petroleum gas (LPG) terminal. The previous researchers focused on single-mode failure for risk assessment. No study exists on LPG plant multimode risk analysis and threat zone prediction using machine learning. This study aims to evaluate the fire and explosion hazard potential of one of Asia’s biggest LPG terminals in India. Areal locations of hazardous atmospheres (ALOHA) software simulations are used to generate threat zones for the worst scenarios. The same dataset is used to develop the artificial neural network (ANN) prediction model. The threats of flammable vapour cloud, thermal radiations from fire, and overpressure blast waves are estimated in two different weather conditions. A total of 14 LPG leak scenarios involving a 19 kg capacity cylinder, 21 tons capacity tank truck, 600 tons capacity mounded bullet, and 1350 tons capacity Horton sphere in the terminal are considered. Amongst all scenarios, the catastrophic rupture of the Horton sphere of 1350 MT capacity presented the most significant risk to life safety. Thermal flux of 37.5 kW/ m2 from flames will damage nearby structures and equipment and spread fire by the domino effect. A novel soft computing technique called a threat and risk analysis-based ANN model has been developed to predict threat zone distances for LPG leaks. Based on the significance of incidents in the LPG terminal, 160 attributes were collected for the ANN modelling. The developed ANN model predicted the threat zone distance with an accuracy of R2 value being 0.9958, and MSE being 202.9061 in testing. These results are evident in the reliability of the proposed framework for safety distance prediction. The LPG plant authorities can adopt this model to assess the safety distance from the hazardous chemical explosion based on the prior forecasted atmosphere conditions from the weather department.

Expert knowledge was elicited to develop a life-safety consequence severity model for Arctic ship evacuations (Browne et al., 2021). This paper presents the associated experimental design and data. Through semi-structured interviews, participants identified factors that influence consequence severity. Through a survey, participants evaluated consequence severity of different ship evacuation scenarios. The methodology represents a two-phased mixed methods design. Life-safety consequence severity is measured as the expected number of fatalities resulting from an evacuation. Participants of the study were experts in various fields of the Arctic maritime industry. Sixteen experts participated in the interviews and the survey (sample size: n = 16). Sample size for the interviews was based on thematic data saturation. Predominantly the same group of experts participated in the survey. Interviews were analysed using thematic analysis. Interview data informed the development of evacuation scenarios defined in the survey. The interview guide and survey questions are presented. Data tables present the codes that emerged through thematic analysis, including code reference counts and code intersection counts. Data tables present the raw data of participant responses to the survey. This data can support further investigation of factors that influence consequence severity, definition of a broader range of evacuation scenarios, and establishment of associated consequence severities. This data has value to Arctic maritime policy-makers, researchers, and other stakeholders engaged in maritime operational risk management.

CO2 hydrogenation to methanol synthesis is one of the effective solutions to mitigate the climate changes and the greenhouse gas emissions. However, the drawbacks of this process needed it to operate at high pressure condition where the possibility of leakage and fatality occur is possible. The simulation of this process was simulated using Aspen HYSYS, ALOHA and Google Earth to analyse the methanol toxicity severity from the high-pressure reactor. The probit will determine the level of the severity. It shows that higher pressure with bigger leakage size may experience high severity for the methanol is achieved the highest severity at 400 bar with the bigger leakage size. As the leakage size and pressure is increasing the exposure of the chemical is increasing, thus increasing the severity to the surrounding. [ABSTRACT FROM AUTHOR]

Several model validation studies on gas dispersion scenarios have been conducted in the past on the Reynolds averaged Navier Stokes (RANS) based eddy viscosity turbulence models. However, many of these studies are based on a limited number of validation cases involving simple geometries and conformal mesh. In the area of safety engineering, the application of RANS-based CFD for consequence analysis is a widely used methodology. Best practice on use of CFD in this context, as the document developed in the COST Action 732 (Franke et al., 2007), focus primarily on validation and verification aspects as well as simulation setup and definition of input data. Guidelines on turbulence models also exist, among which the ERCOFTAC CFD Best Practice Guidelines, and the works of Meroney et al. (2016) and Mcbride et al. (2001). However, there is no unique recommended model for dispersion simulations. The objective of the present study is to assess the three well-known RANS eddy viscosity models, namely, Standard k-ε, Re-Normalization group (RNG) k-ε and Realizable k-ε, in a representative range of gas dispersion cases by comparing models" behavior with experimental data. The current validation cases include dense CO[sub 2] release in a cross-wind, impinging hydrogen jet, and a dense chlorine jet release in an industrial site. All the simulations were conducted using the commercial CFD code FLACS. Turbulence models were assessed based on the ability to reproduce experimental concentrations, required computational-time and numerical-stability. Overall, Standard k-ε and RNG k-ε models were found to be reasonably good in all cases. Nevertheless, Realizable k-ε model shows promise in yielding good results in cases involving complex-geometries and dense-phase gas-releases. These results may also be explained with the interplay between the Porosity/Distributed Resistance subgrid models used in FLACS and turbulence models. [ABSTRACT FROM AUTHOR]

Abstract This paper describes a methodology for simulating the structural response of vented enclosures during hydrogen deflagrations. The paper also summarises experimental results for the structural response of 20-foot ISO (International Organization for Standardization) containers in a series of vented hydrogen deflagration experiments. The study is part of the project Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations (HySEA). The project is funded by the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 671461. The HySEA project focuses on vented hydrogen deflagrations in containers and smaller enclosures with internal congestion representative of industrial applications. The structural response modelling involves one-way coupling of pressure loads taken either directly from experiments or from simulations with the computational fluid dynamics (CFD) tool FLACS to the non-linear finite element (FE) IMPETUS Afea Solver. The performance of the FE model is evaluated for a range of experiments from the HySEA project in both small-scale enclosures and 20-foot ISO containers. The paper investigates the sensitivity of results from the FE model to the specific properties of the geometry model. The performance of FLACS is evaluated for a selected set of experiments from the HySEA project. Furthermore, the paper discusses uncertainties associated with the combined modelling approach. Highlights • One-way coupling structural modelling of measured/simulated pressure loads. • Coupled Computational Fluid Dynamics (CFD) and Finite Element (FE) model. • Characterisation of the structural response of 20-foot ISO container. • Investigation of the 'quasi-static' response of 20-foot ISO containers. • Potential model system to derive pressure-impulse diagrams for containers. [ABSTRACT FROM AUTHOR]

Abstract This paper summarises the results from a blind-prediction study for consequence models used for estimating the reduced explosion pressure and structural response in vented hydrogen deflagrations. The work is part of the project Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations (HySEA). The scenarios selected for the blind-prediction entailed vented explosions with homogeneous hydrogen-air mixtures in a 20-foot ISO (International Organization for Standardization) container. The test program included two configurations and six experiments, i.e. three repeated tests for each scenario. The comparison between experimental results and model predictions reveals reasonable agreement for some of the models, and significant discrepancies for others. The results from the first blind-prediction study in the HySEA project should motivate developers to improve and validate their models, as well as to update documentation and guidelines for users of the models. Highlights • Summary of results from the first blind-prediction benchmark exercise in the HySEA project. • Full-scale vented hydrogen deflagration experiments in 20-foot ISO containers. • Reasonable agreement between model predictions and experiments for most models. • Significant spread in predictions from different users of the same model system. • Significant effect of grid resolution for some model systems. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics has been used for consequence modelling in place of traditional methodologies, to obtain more accurate results and better understanding of complex problems. With today's computational technology, it is not difficult to run CFD simulations for several selected scenarios. However, its use to produce a full quantitative risk assessment, involving thousands of scenarios, is impractical given the extensive computational resources required. In this paper, a modified QRA methodology proposed recently, with the integration of sampling algorithms, surrogate models and error measures, is extended to a higher dimensional hydrocarbon pool fire problem. The characteristics, advantages and challenges of a local linear model and a global non-linear model are identified and addressed. The addition of time as an input variable to surrogate models provides an extension of the methodology to safety studies where the resolution of time-varying output is important. We demonstrate the effectiveness of the modified QRA methodology through a case study of pool fire in a hydrocarbon storage facility. [ABSTRACT FROM AUTHOR]

In the current work the rhoReactingBuoyantFoam solver was customised for performing gas leak and gas dispersion modelling. Using experimental data from gas leaks the proposed modelling was investigated for subsonic and sonic releases. The gas molar fraction and velocity decay along the jet centreline were calculated using the modified reacting solver, and the numerical findings were compared with available experimental data. Different approaches for the turbulence closure problem were considered using standard two-equation models. The numerical stability of the solver was also investigated varying the CFL number for a set of simulations. The work also considered the modelling of gas cloud volume in a real engineering case. Standard computational setup for ANSYS-CFX was applied, and the same set of scenarios were modelled in OpenFOAM using the modified rhoReactingBuoyantFoam solver. The analysis considered 5 different leak directions and 4 wind directions in a typical industrial site. For all scenarios simulated, very good agreement with experimental data and with the commercial CFD (computational fluid dynamics) tool considered in this study was observed. The results are within 10% tolerance intervals. Detailed information of the modelling is also provided, which enable any CFD user to reproduce the results and also apply it for future analysis. [ABSTRACT FROM AUTHOR]

• A general method to combine multiple consequences posed by Arctic ship accidents. • Ecological and socio-economic consequences of an oil spill and life-safety consequences of an evacuation in Arctic waters are considered. • Consequence types are monetized and summed to quantify a total consequence cost. • A framework to qualitatively rate total consequence severity is proposed. • Total consequence severity for different ship types and regions in the Canadian Arctic are evaluated. Risk aggregation is the process of combining multiple individual risks to develop a better understanding of the overall risk on a system. Different risks can have different consequences and different units of measure. This study contributes to the process of risk aggregation by presenting a general method to combine multiple consequences posed by an Arctic ship accident. The method considers ecological and socio-economic consequences of a potential oil spill, and life-safety consequences of a potential ship evacuation. Existing models for each consequence type are adopted. Individual consequence types are monetized and combined to quantify total consequence cost for a given accident scenario. A framework is proposed to assign a qualitative rating for total consequence severity. The qualitative scales of the framework are established using the quantitative method. Total consequence severity is evaluated for different ship types and regions in the Canadian Arctic. Results indicate that Arctic ship accidents involving oil tankers in environmentally sensitive regions and cruise ships in regions associated with long response times are worst-case scenarios, with similar total consequence severity levels. Implications for safe Arctic shipping are that on the basis of total consequence severity, mitigating the potential consequence severity of Arctic cruise operations is of near equal priority to that of Arctic tanker operations. Evaluating total consequence severity of potential Arctic ship accidents provides decision-makers and risk analysts with a data-driven tool to integrate multidisciplinary knowledge for the assessment, management, and communication of Arctic shipping risks. [ABSTRACT FROM AUTHOR]

This paper discusses the validation of discharge and subsequent atmospheric dispersion for both unpressurised and pressurised carbon dioxide releases using the consequence modelling package Phast. The paper first summarises the validation of the Phast dispersion model (UDM) for unpressurised releases. This includes heavy gas dispersion from either a ground-level line source (McQuaid wind-tunnel experiments) or an area source (Kit-Fox field experiments). For the McQuaid experiments minor modifications of the UDM were made to support line sources. For the Kit Fox experiments steady-state and 20-s finite-duration releases were simulated for both neutral and stable conditions. Most accurate predictions of the concentrations for finite duration releases were obtained using the UDM Finite Duration Correction method. Using experiments funded by BP and Shell and made available via DNV's CO2PIPETRANS JIP, the paper secondly summarises the validation of the Phast discharge and dispersion models for pressurised CO2 releases. This modelling accounted for the possible presence of the solid CO2 phase following expansion to atmospheric pressure. These experiments included both high-pressure steady-state and time-varying cold releases (liquid storage) and high-pressure time-varying supercritical hot releases. Both the flow rate and the concentrations were found to be predicted accurately. The above validation was carried out with no fitting whatsoever of the Phast extended discharge and dispersion models. [ABSTRACT FROM AUTHOR]

This paper describes part of a programme of work undertaken at the Health and Safety Laboratory (HSL) to investigate the behaviour of selected water-reactive chemicals. Following an accidental release, such substances react exothermically with any water present, generating acidic vapours. The STAWaRS (Source Term Assessment of Water Reactive Substances) software was developed for the Health and Safety Executive (HSE) by ESR Technology to model this complex process. The aims of the study described here were to provide experimental validation of the heats of hydrolysis used within STAWaRS, and to perform sensitivity studies on selected STAWaRS input parameters. The heat of hydrolysis of acetyl chloride was measured and showed good correlation with the value used within STAWaRS. Some of the variables that influence the severity of acetyl chloride spills are examined, with reference to predictions made by the STAWaRS model. The heats of hydrolysis of titanium tetrachloride previously measured at HSL are also discussed, and the effect of adopting these experimentally derived values for modelling spills is shown for a hypothetical land use planning case. This study demonstrates the importance of using experimentally validated values for STAWaRS input parameters. [ABSTRACT FROM AUTHOR]

Abstract: Projects in carbon capture and storage technologies for energy production involve the transport of vapour, liquid and supercritical CO2 and CO2/hydrocarbon gas mixtures via pipelines and process systems with subsequent injection into wells, e.g. offshore under the seabed. In addition several chemical companies often store and transport large quantities of CO2 and this may also represent a hazard. There is a need to model potential loss of containment scenarios for risk assessment and design purposes for such installations. It is observed that several models used in quantitative risk analyses and hazard assessment studies are not able to take into account modelling of the thermodynamics of CO2 in case of accidental releases from dense or supercritical conditions. Statoil together with DNV therefore initiated a project to further improve the Phast code for modelling of CO2 releases. The work and methodology derived in this project have mainly been developed by Det Norske Veritas (DNV), but with significant co-operation and input by Statoil. The consequence modelling package Phast examines the progress of a potential incident from the initial release to the far-field dispersion including the modelling of rainout and subsequent vaporisation. The original Phast 6.54 models allow the released chemical to occur only in the vapour and liquid phases. The new Phast 6.6 models were extended to also allow for the occurrence of fluid to solid transition in case of CO2 releases. This applies both for the post-expansion state in the discharge model, as well as for the thermodynamic calculations by the dispersion model. Here it is assumed that no solid deposition occurs on the ground. The current paper documents work regarding modelling by Phast 6.6 of discharge and atmospheric dispersion of carbon dioxide, including a detailed sensitivity analysis for a wide range of scenarios (base cases) including high-pressure cold releases (liquid storage) and high-pressure supercritical releases (vapour storage) from vessels, short pipes or long pipes. The objectives of this work were to examine the effect of input parameters on key output data, to ensure robustness of the models, and to identify further model improvements where deemed to be necessary. [Copyright &y& Elsevier]

Abstract: In assessing the safety of engineering systems in the context of quantitative risk analysis one of the most important consequence types concerns the loss of life due to accidents and disasters. In this paper, a general approach for loss of life estimation is proposed which includes three elements: (1) the assessment of physical effects associated with the event; (2) determination of the number of exposed persons (taking into account warning and evacuation); and (3) determination of mortality amongst the population exposed. The typical characteristics of and modelling approaches for these three elements are discussed. This paper focuses on “small probability–large consequences” events within the engineering domain. It is demonstrated how the proposed approach can be applied to various case studies, such as tunnel fires, earthquakes and flood events. [ABSTRACT FROM AUTHOR]

Malaysia, like any other country has experienced a number of chemical accidents in the past, hence the necessity to undertake thorough consequence analysis to mitigate similar occurrences in future. The water treatment plant in question keeps more than 18.6 MT (metric tonnes) of chlorine to disinfect water for the community in municipal area. However, chlorine is a hazardous chemical that can cause serious injuries, loss of life and damage to properties and environment if not handled properly. Hence using the Environmental Protection Agency (EPA) methodology an offsite consequence analysis was conducted to determine the potential impacts in the event of catastrophic release of chlorine at the water treatment plant. A “worst-case release scenario” and 7ldquo;alternative scenario” were developed for the treatment plant. The results obtained from the use of TRACE software showed that a potential hazard exists, even under average annual weather conditions. Within a 6 km radius, an estimated number of 102000 people within the zone for a 3 ppm chlorine exposure may be affected due to a worst-case release. The consequence isopleth for the respective chlorine concentration indicates that the chlorine plume is directed towards the administration building and process unit facilities of the plant. Hence, it is critical to ensure that all personnel within the plant are provided with sufficient training on the emergency response plan and the application of the relevant personnel protective equipment (PPE) in the event of accidental releases. Although the hazard exists, the risk to the public may be low. An alternative release scenario would be limited due to the use of safety and mitigation systems incorporated into the chlorinating system, but the plant requires other supporting safety measures to supplement the existing facility's inherent safety. Such measures are essential to ensure that in the event of a potential incident at the plant onsite and offsite effects could be minimised to ensure the risk is as low as reasonably practicable (ALARP). [ABSTRACT FROM AUTHOR]

Risk-based decision-making is central to the development of Arctic shipping policy and regulation. Policy-makers within the International Maritime Organization rely on the Formal Safety Assessment (FSA) methodology to evaluate proposed regulatory changes and Arctic ship operators rely on it to establish operating limits and procedures. The FSA recommends incorporating life-safety consequence in the assessment of maritime industry risk. This paper presents an expert-based assessment of the factors that influence the potential for loss of life during an Arctic ship evacuation and quantified consequence severities for a range of evacuation scenarios. A two-phased mixed methods design is used to elicit expert knowledge. Sixteen experts in the fields of Arctic seafaring, policy and regulation, academia and research, and ship design participated in the study. Semi-structured interviews elicited perspectives on the factors that influence the expected number of fatalities resulting from an evacuation in Arctic waters. Surveys were administered in which evacuation scenarios were rated for the level of life-safety consequence severity they pose. This study provides a scenario-based life-safety consequence model for Arctic ship evacuations. Results show evacuation of passenger vessels poses the highest consequence severity of evaluated ship types. Response time and the time available to evacuate have the greatest levels of influence on consequence severity. Implications for Arctic marine policy include the need for enhanced competency and training for Arctic ship crews and SAR services, continued research and development of Arctic life-saving appliances to satisfy Polar Code functional requirements, heightened regulatory oversight of Arctic cruise operations, and consideration of inclusion of fishing vessels under the Polar Code. Application of the results to the FSA methodology is discussed. • Conceptual framework for consequence of Arctic ship evacuations. • Estimates of expected numbers of fatalities for Arctic ship evacuations. • Passenger vessels pose the highest life-safety consequence severity. • Response time and uncontrolled evacuation are predominant contributors to consequence severity. • Worst-case scenario: uncontrolled evacuation, passenger vessel, severe weather; hundreds of expected fatalities. [ABSTRACT FROM AUTHOR]