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When performing process hazard analysis (PHA), basic consequence evaluation methods are often sufficient. However, sometimes these approaches lead to overly conservative estimates, and we need to conduct more thorough dispersion modeling to refine the potential impact. This paper will evaluate different methods for determining the consequence severity of a potential release, starting with a basic approach, and ultimately using probit functions. Probit functions are used to predict the lethality of a potential release following acute inhalation exposure from a toxic release. Developing probits to use in modeling can be challenging, for obvious reasons. In the absence of human or animal toxicological data, estimates of "pseudo‐probits" can be used in lieu of values derived from toxicological data. The analysis makes use of the PHAST™ program that uses probits as part of its basic tool set. While probits are not new to the industry, this paper provides a simple method for estimating pseudo‐probits for materials that do not have readily available probit data. [ABSTRACT FROM AUTHOR]

BACKGROUND: The hazardous material release has frequently occurred worldwide. As a respiratory stimulant and a toxic substance, ammonia has numerous adverse effects on human health. OBJECTIVE: The purpose of this study was to evaluate the human vulnerability and toxic effects of both chronic and acute respiratory exposure to ammonia. METHODS: This study was conducted in an ice factory. Ammonia reservoirs were selected as the danger center. The scenarios were evaluated from the perspective of the worst-case. The Emergency Response Planning Guidelines 1–3 was used to predict the dangerous concentrations in acute exposure. The probability of human vulnerability was estimated using the Probit model. PHAST 7.2 software was used to model consequences. As a measure of chronic exposure to ammonia, NMAM 6016 was used. A respiratory symptom questionnaire developed by the American Thoracic Society was used for collecting respiratory symptom histories. RESULTS: The ERPG3 level or concentration of 750 ppm was found at a distance of 617.71 and 411.01 meters from tanks, respectively, as a result of a rupture in reservoir 1 over a period of two halves of the year. It was found that the highest probit values for tank 2 at distances of zero, 25, 50, 75, 100, 125, and 150 meters were 9.55, 5.92, 5.47, 4.82, 4.23, 3.56 and 2.96, respectively. The prevalence of pulmonary symptoms, which include coughing, dyspnea, phlegm, and wheezing, was 28%, 19%, 15%, and 26% in the chronic exposure group. CONCLUSION: In the event that an ammonia reservoir ruptures catastrophically, it may cause human injury at ERPG-2 or ERPG-3 levels. Results revealed that exposure to this substance can impose many pulmonary symptoms on the respiratory system of workers in industries. In order to reduce the vulnerability of humans to potential release scenarios, control measures must be implemented. Also, preventive and mitigation measures can be designed to enhance safety and resilience against the release of hazardous materials. [ABSTRACT FROM AUTHOR]

One of the core elements of fire protection for petrochemical processing plants is the consideration of passive fire protection (PFP). This general category, often referred to as fireproofing, is addressed in the American Petroleum Institute (API)‐recommended practice (RP) 2218. This RP provides guidelines for the selection and application of fireproofing with what is mostly a qualitative risk assessment approach. The logic focuses on predicting pool fires based on rough characterizations of system properties combined with equipment layout. Although pool fire impacts are often localized, jet fires can affect larger areas. API RP 2218 addresses jet fires in an appendix because of their unpredictable nature, leaving pool fire exposures as the default basis for structural fireproofing. To properly account for both fire types, fire exposure can be evaluated with quantitative risk analysis (QRA) tools that incorporate both jet and pool fire impacts for a wide variety of accident scenarios, weather conditions, and release orientations. By evaluating the thermal radiation impacts of fires in relation to the vulnerability of steel structural elements, a QRA‐based approach to placement of PFP can be achieved. This approach has the benefit of applying PFP where it is needed the most, to best protect a company's infrastructure. [ABSTRACT FROM AUTHOR]

This study provides a defensible argument for the inclusion of the A2 Pasquill weather parameter in dispersion modeling, in addition to the typical F2 and D5. The A2 parameter conservatively models gas releases that concentrate at ground level, thus allowing for a more robust design of vent heights, surrounding structures/equipment and safety measures. For this investigation, 12 case studies of common hydrocarbon and aromatic gas mixtures were developed in PHAST (Process Hazard Analysis Software Tool) version 8.6. Each case varied in temperature, release pressure (velocity), and molecular weight (MW) to simulate dense gases likely to tend toward ground level. Subsequently, each case study was modeled with the Pasquill Atmospheric Stability Classes, A2, D5, and F2, to visualize the dispersion of dense gases under different weather conditions and evaluate which weather parameter would be most inclusive of high‐severity scenarios. Results demonstrate that dense (colder than dew point, heavy, pressurized) gases yield highest ground‐level concentrations using the A2 atmospheric condition, and the further the release temperature falls below the mixture's dew point, the greater the mixture concentration at ground level. Consequence modeling recommendations are discussed, and specific gas properties are addressed that necessitate using a model that is conservative in its estimation of ground‐level concentrations. [ABSTRACT FROM AUTHOR]

The use of hydrogen as a fuel and energy carrier is increasing globally. Existing processes are being expanded, and hydrogen is also being incorporated into novel technologies and processes. As new hydrogen applications and processes are being developed, it is important for industry professionals to understand the associated hazards and how they differ from the hazards of hydrocarbon fuels. While best practices and risk management strategies for hydrocarbon fuel processes are mature and generally known within thre industry, the hazards of hydrogen processes, such as liquid storage tanks and fuel dispensers, are less commonly understood by those who may be planning to enter this industry. The objective of this paper is to explain the hazards of hydrogen and to provide a comparison of these hazards with those of commonly used hydrocarbon fuels through a review of the flammable hazards, consequence modeling, and select hydrogen‐release incidents. The analysis will provide current industry risk practitioners with useful guidance to understand the hazards associated with this increasingly popular fuel. This paper provides information in three main sections. The first section provides a review and comparison of fire and explosion hazards for hydrogen as compared to hydrocarbon fuels. Second section provides consequence modeling results comparing hydrogen and hydrocarbon fuels for similar release scenarios using a common software model (DNV Phast version 8.71). Third section provides a review of select hydrogen incidents. [ABSTRACT FROM AUTHOR]

The drive by the Nigerian government to increase the usage of liquefied petroleum gas (LPG) within the country has led to the rapid growth of refill stations without adherence to international safety and regulatory guidelines on gas handling. This has increased associated hazards such as explosions and fires leading to loss of life and damage to properties. This study employed the Areal Locations of Hazardous Atmospheres software to model the consequences of explosion and fire due to accidental leakage of LPG into the environment in four selected locations in the Ilorin metropolis under four scenarios. The longest threat zones were observed in Scenario II in all the selected refill stations. The flammability hazard for gas station 1 was predicted to be 98 and 238 m for the red and yellow threat zones, respectively. For thermal radiation, the predicted threat zones are 17, 27, and 43 m for 10, 5, and 2 kW/m2, respectively. January was observed to have the longest threat zones, particularly in the flammability hazard which indicates the influence of atmospheric weather conditions on dispersion. To reduce the accidental release of LPG, continuous enlightenment on safety rules is mandatory for all. [ABSTRACT FROM AUTHOR]

Background: The present study aimed to consequence modeling and root cause analysis of the real explosion of a methane pressure vessel in separation unit of a gas refinery in Iran. Method: ology: This study was performed in a gas refinery in the south of Iran. The studied scenario was the actual scenario that occurred in the studied pressure vessel. Modeling of possible consequences was performed using PHAST 7.2 software. Also, the root causes analysis of the accident was performed using experts' brainstorming. Results: At radii of 15 and 45 m, the radiation level reaches 12.5 and 4 kW/m2, respectively. In the late explosion worst-case, the vapor cloud explodes after reaching a distance of 20 m from the pressure vessel. At radii of 20 m, 25 m, and 150 m from the center of the explosion, the pressure reaches 0.2068, 0.1379, and 0.02068 bar, respectively. In the Early Explosion Overpressure, the acceptable pressure is obtained at a distance of 193 m. Moreover, in the Early Explosion Overpressure radiation, at radii of 28 m, 38 m, and 193 m, the pressure reaches 0.2068, 0.1379, and 0.02068 bar, respectively. Conclusion: The findings revealed that creating an appropriate risk management algorithm with a focus on consequence modeling can be an effective step towards reducing losses in the process industry. This results can create a novel insight in comparing the two reactive and proactive approaches and also reveal the effectiveness of consequence modeling in reducing the severity of risks.

Objectives. Biogas production in treatment plants for energy generation has increased in recent years. This study aimed to model the consequence of biogas release in a large urban treatment plant. Methods. The study modeled biogas storage tank consequences in a large urban treatment plant in Iran. Due to potential for biogas harmfulness, three consequences of toxic release, fire and explosion were evaluated. Scenarios were evaluated in the worst-case situation. All modeling steps were performed using PHAST version 7.2. Results. In the case of catastrophic reservoir rupture in summer, distances of 3788.94, 128.86 and 91.72 m from the reservoir in the wind direction will be in the range of 100, 500 and 1000 ppm biogas, respectively. Study of pressure values due to explosion in the catastrophic rupture scenario revealed that distances of 57.19, 14.70 and 115.84 m from the biogas reservoir were in the range of 0.02, 0.13 and 0.2 bar pressure increase, respectively. Conclusion. Due to the treatment plant's location in a dense urban area, biogas dispersion could lead to exposure of many people to high-risk areas. Therefore, taking control measures comparable with the consequence modeling output can be a practical step toward reducing vulnerability against such incidents. [ABSTRACT FROM AUTHOR]

Analytical models and the prediction of accidents and their consequences are important tools for preventing accidents in the industry. Therefore, the present study was conducted to review process accident consequence modeling in Iran (2006–2022), helping improve incident modeling, and creating a context for preventing these accidents. In this study, the articles of 5 international Embase Medline/PubMed databases, ProQuest, Scopus, Google Scholar, and Web of Science, and four Iranian databases SID, MagIran, IranMedex, and IranDoc were examined using the PRISMA checklist. After reviewing the studies, 40 articles were included in the final analysis. The results showed that 25 studies used PHAST software, 11 studies used ALOHA software and 4 studies used ALOHA and PHAST software together. The highest number of studies was conducted in Imam Khomeini Port and Asaluyeh city, respectively. In addition, the number of studies published in Persian was more than in other studies. There was no similar agreement between the results of the two software in providing correct results at low concentrations. PHAST software also provided more accurate results than ALOHA over longer distances in stable and relatively stable weather conditions. The study and identification of hazards and scenarios in the studies that used PHAST software were more, more accurate and more coherent than in the studies that used ALOHA software. It is suggested that in future studies the same scenario can be compared with PHAST, ALOHA, and newer modeling software such as Fire Dynamics Simulator (FDS).

For facilities where hazardous events of high consequences can happen, quantitative risk analysis (QRA) is used to determine whether the risk is tolerable against the risk criteria of the operating company or local regulations. Specific risk reduction measures may need to be defined and evaluated based on the QRA. A risk analysis considering both consequences and frequencies is typically time‐consuming and requires the collection of sufficient information regarding process, equipment, operation methods, weather, geographic conditions, the population, and so forth. Business management often requires prompt decisions in a fast‐paced business environment; therefore, the risk analysis must be done expediently to provide adequate information for business decisions. Some examples related to industrial gas facilities are summarized to show simplified analyses done to help define risk reduction measures and priorities in a shorter time frame than typically possible by using detailed quantitative risk assessment. Some generic methods for simplification are proposed. [ABSTRACT FROM AUTHOR]

Synergistic effects of pool fires in fire-induced domino accidents can result in greater damage than single pool fire. Existing research mainly adopts a superposition method based on simplified assumptions to analyze the contribution of synergistic effect of pool fires for domino effects. Therefore, the synergistic effect of pool fires has not been well understood. In this study, a new CFD-based method is developed to model the synergistic effect of pool fires. Case studies were carried out taking double pool fires as an example. The influence of key factors, including wind speed, vertical fire location, fuel type, and separation distance has been investigated quantitatively. The results demonstrated that the proposed CFD based approach can model the consequences of pool fires more comprehensively and assess the domino effects under synergistic effect more precisely than the traditional superposition method. Compared with the single pool fire, the synergistic effect of double pool fires can increase the probability of domino accidents for the adjacent tanks at the downwind by six orders of magnitude. In addition, it is observed that the received maximum radiation heat flux and escalation probability of the target tank in the downwind direction rise with increased wind speed. While the maximum radiation heat flux received by target tanks and escalation probability reduced with increased separation distance and vertical fire location. Moreover, according to the minimum safety distance recommended by present design standards, the synergistic effect of double pool fires in diesel storage tank farms will lead to a higher escalation probability of near equipment than gasoline storage tank farms. This study can be used to predict accident consequences and assess the domino effect under the synergistic effect of pool fires, and guide the layout optimization of the chemical storage tank area. [ABSTRACT FROM AUTHOR]

The release of toxic chemicals is an important hazard of chemical plants. The purpose of this study is to compare the chemical exposure index (CEI) and consequence modeling to determine the hazard distance of toxic chemical release, utilizing a gas refinery as the case study. The CEI was utilized and considerable release scenarios were determined. The process hazard analysis software tool model was performed for consequence modeling of the scenarios with the highest airborne quantity. In the case of toxic chemical release based on both the CEI and consequence modeling, the sludge catcher unit was identified as the most dangerous unit. Hazard distances calculated by the CEI are significantly greater than those using consequence modeling. This is acceptable in terms of safety, but may not be applicable in reality. The results of the study showed a procedure for selecting an appropriate method in order to reduce costs and time. [ABSTRACT FROM AUTHOR]

[Display omitted] It is crucial for emergency responders to makes a quick and accurate prediction of toxic chemical dispersions, which can lead to massive injuries and casualties. In this study, a toxic dispersion database is constructed by PHAST simulations, which consist of 30,022 toxic release scenarios of 19 chemicals. A quantitative consequence prediction model is then developed based on this database to efficiently and accurately predict dispersion downwind distances. Random forest, gradient boosting, and deep neural network algorithms are implemented and compared to find the best performing method for the model construction. The deep neural network is found to have the highest accuracy with the test set R2 higher than 0.994 and RMSE less than 0.1 for all key dispersion ranges. The developed toxic dispersion prediction models can be used to quickly generate instant toxic dispersion range estimations for any toxic chemicals at much lower computational costs. [ABSTRACT FROM AUTHOR]

Background and Objective: Ethylene oxide (EO) is a very toxic and dangerous substance with a high potential for explosion and fire. Ethylene oxide units are among the most hazardous units in petrochemical industries. This study was designed to analyze and model the consequences of ethylene oxide storage tanks explosion in one of Iranchr('39')s petrochemical industries. Materials and Methods: In this study, the consequences of the ethylene oxide storage tanks explosion in a petrochemical industry was identified and analyzed. This study was conducted in 2017 using PHAST software version 6.54. For this study, two climate conditions including the first climate conditions (spring and summer) and the second climate conditions (autumn and winter) were considered. Results: The results of the modeling for the first and second climate conditions showed that there were possibility of severe damages due to the explosion consequences up to 204 and 256 meters, respectively. In addition, based on the criteria for assessing the consequences of accidents associated with damage levels, such as the explosion wave, the wind speed and direction due to the sudden release scenario and the numerical results related to the modeling, the consequence of this scenario in the second climate conditions (autumn and winter) was higher than the first climate conditions (spring and summer). Conclusion: The findings of the study indicated that, in addition to the high risk of explosion of ethylene oxide storage tanks, the modeling scenarios in different climate conditions have different consequences. Thus, more attention should be paid to safety of these equipment as risk centers in the petrochemical industry and similar industries.

Introduction: Being aware of the explosion, fire radius, and their damages, has an important role in accident prevention methods. Therefore, the aim of this study was modeling and evaluation of the consequences of propylene oxide spill in a petrochemical company. Material and Method: The QRA method including seven steps was used in this study. In the present study, in order to examine and modeling of the propagation propylene oxide, first a familiarization with the process information of the unit was done then, a risk assessment was carried out adopting HAZOP technique to identify existing hazards. Consequence analysis in a process unit includes: selecting important scenarios, characterizing scenario, modeling the consequences of scenarios, analyzing the results and determining the percentage of mortality. PHAST software version 6.51 was used for modeling of outcomes and assessment propylene leak. Result: urves of the firing zones of sudden release of propylene oxide showed that the influence puts are included up to radius of 0.15 meters in the scenario of leakage 5 mm, in scenarios with leaks 25 mm to a radius of 1.1 meters and in scenarios with leakage of 100 mm to a radius of 39 meters. The maximum intensity of flash fire in the initial point Scenario 5 mm was 4.2 kW/m2, in the scenario of radiation leakage was 25 mm at the distance to 5 meters from the fire intensity up to maximum of 9 kW/m2, and also in the scenario with 100 mm flash fire radiation leak at an earlier point fire was 14 kW/m2. The maximum intensity of thermal radiation at the distance to 5 meters up to 16.5 kW/m2, and maximum distance of 80 meters around the reservoir affected. The mortality rate of flash fire has exposed employees, was 50 percent. Conclusion: Many accidents caused by leakage and explosion were due to corrosion, spoil tanks and equipment, and the majority of such accidents can be prevented by technical inspections and continuous audits.

Featured Application: A risk assessment framework that supports Arctic voyage planning and real-time operational decision-making through assignment of operational criteria based on the likelihood of ice-induced damage and the potential consequences. The International Code for Ships Operating in Polar Waters (Polar Code) was adopted by the International Maritime Organization (IMO) and entered into force on 1 January 2017. It provides a comprehensive treatment of topics relevant to ships operating in Polar regions. From a design perspective, in scenarios where ice exposure and the consequences of ice-induced damage are the same, it is rational to require the same ice class and structural performance for such vessels. Design requirements for different ice class vessels are provided in the Polar Code. The Polar Operational Limit Assessment Risk Indexing System (POLARIS) methodology provided in the Polar Code offers valuable guidance regarding operational limits for ice class vessels in different ice conditions. POLARIS has been shown to well reflect structural risk, and serves as a valuable decision support tool for operations and route planning. At the same time, the current POLARIS methodology does not directly account for the potential consequences resulting from a vessel incurring ice-induced damage. While two vessels of the same ice class operating in the same ice conditions would have similar structural risk profiles, the overall risk profile of each vessel will depend on the magnitude of consequences, should an incident or accident occur. In this paper, a new framework is presented that augments the current POLARIS methodology to model consequences. It has been developed on the premise that vessels of a given class with higher potential life-safety, environmental, or socio-economic consequences should be operated more conservatively. The framework supports voyage planning and real-time operational decision making through assignment of operational criteria based on the likelihood of ice-induced damage and the potential consequences. The objective of this framework is to enhance the safety of passengers and crews and the protection of the Arctic environment and its stakeholders. The challenges associated with establishing risk perspectives and evaluating consequences for Arctic ship operations are discussed. This methodology proposes a pragmatic pathway to link ongoing scientific research with risk-based methods to help inform recommended practices and decision support tools. Example scenarios are considered to illustrate the flexibility of the methodology in accounting for varied risk profiles for different vessel types, as well as incorporating input from local communities and risk and environmental impact assessments. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to analyze risk of accidental gasoline release in the storage tank of gasoline 59-TK-158 situated in complex GL1/K Skikda using quantitative risk assessment based on HAZOP and bow tie to identify and quantify the sources of the unwanted event. Afterward, we identified the areas that are exposed to different industrial accidental effects such as (thermal, flammable and overpressure), using the software Phast as a tool for simulation. The simulation results show the distances of the affected area, to understand the risk consequences related to the affected area of each scenario. Based on this simulation, using the societal risk curves FN to assess the accidental risk inevitably affects people in the surrounding area. This explicitly denotes the relation between the frequency of occurrence and the number of fatalities generated by this accident on a two-dimensional diagram. It aims to find which scenario that is acceptable and which needs more improvement to lower the consequences related to it in a matter of safety. This work was conducted for the first time in GNL Skikda, specifically in a storage tank using a combination between HAZID, bow tie and FN curve. The intention of this combination is to explain deferent industrial phenomenal specially to avoid disasters such as what happened in 2004 and 2005 in the industrial area of Skikda. That is what makes the approach practically more helpful in the use of safety barriers and industrial decision making. [ABSTRACT FROM AUTHOR]

Abstract Different causes lead to accidental oil spills from fixed and mobile sources in the marine environment. Therefore, it is essential to have a systematic plan for mitigating oil spill consequences. In this research, a general DSS is proposed for passive and active response planning in Persian Gulf, before and after a spill. The DSS is based on NOAA's advanced oil spill model (GNOME), which is now linked with credible met-ocean datasets of CMEMS and ECMWF. The developed open-source tool converts the results of the Lagrangian oil spill model to quantitative parameters such as mean concentration and time of impact of oil. Using them, two new parameters, emergency response priority number (ERPN) and risk index (RI), are defined and used for response planning. The tool was tested in both deterministic and probabilistic modes, and found to be useful for evaluation of emergency response drills and risk-based prioritization of coastal areas. Graphical abstract Unlabelled Image Highlights • A decision support system (DSS) is proposed for oil spill response planning. • The DSS is based on a fast Lagrangian oil spill model (GNOME). • Deterministic consequence modeling facilitates response drills. • High risk areas are determined by probabilistic risk analysis (PRA). • PRA results are used in optimal siting of emergency response stations. [ABSTRACT FROM AUTHOR]

A consequence analysis was performed in one of the gas refineries in Iran to investigate the risks andpotential losses resulted from accidents. Specifically, the consequences of an explosion in LPGspherical tanks were modeled using PHAST and MATLAB software. In this paper, three methods ofcalculation of PHAST software TNT, multi-energy, and BST were used. The results showed thatmulti energy method is the best method to evaluate overpressure. It was 0.150 bar and 0.159 bar in adistance of 1000 m far from the blast using PHAST and MATLAB respectively. This overpressurecan damage a wall with 30 cm thickness. It also affects the human threshold (1%) ruptured eardrum.Finally, it was found that 100% lethality in a minute happened at 285.5 m and 37.5 kW/m2 when theexplosion happened.

The International Code for Ships Operating in Polar Waters (Polar Code) was adopted by the International Maritime Organization (IMO) and entered into force on 1 January 2017. It provides a comprehensive treatment of topics relevant to ships operating in Polar regions. From a design perspective, in scenarios where ice exposure and the consequences of ice-induced damage are the same, it is rational to require the same ice class and structural performance for such vessels. Design requirements for different ice class vessels are provided in the Polar Code. The Polar Operational Limit Assessment Risk Indexing System (POLARIS) methodology provided in the Polar Code offers valuable guidance regarding operational limits for ice class vessels in different ice conditions. POLARIS has been shown to well reflect structural risk, and serves as a valuable decision support tool for operations and route planning. At the same time, the current POLARIS methodology does not directly account for the potential consequences resulting from a vessel incurring ice-induced damage. While two vessels of the same ice class operating in the same ice conditions would have similar structural risk profiles, the overall risk profile of each vessel will depend on the magnitude of consequences, should an incident or accident occur. In this paper, a new framework is presented that augments the current POLARIS methodology to model consequences. It has been developed on the premise that vessels of a given class with higher potential life-safety, environmental, or socio-economic consequences should be operated more conservatively. The framework supports voyage planning and real-time operational decision making through assignment of operational criteria based on the likelihood of ice-induced damage and the potential consequences. The objective of this framework is to enhance the safety of passengers and crews and the protection of the Arctic environment and its stakeholders. The challenges associated with establishing risk perspectives and evaluating consequences for Arctic ship operations are discussed. This methodology proposes a pragmatic pathway to link ongoing scientific research with risk-based methods to help inform recommended practices and decision support tools. Example scenarios are considered to illustrate the flexibility of the methodology in accounting for varied risk profiles for different vessel types, as well as incorporating input from local communities and risk and environmental impact assessments.

The gas dispersion simulation in complex urban environment posts challenges on consequence analysis. Though computational fluid dynamics (CFD) are general approaches to provide building-resolving estimates, the time consuming calculation and complex process of modeling limit their application for emergency response. In this paper, a cellular automata dispersion model is prompted to simulate continuous point release of propane in 3-D domain with ground obstructions. An artificial neural network is employed to calculate the temporal state transition of cellular automata. To provide data for the neural network to train, fire dynamic simulator (FDS) code is adopted to simulate 100 scenarios of propane release from a fixed position in pre-specific domain with different combinations of meteorological conditions and source parameters. A proportion of the simulation results is selected to train the artificial neural network with different transition rules derived from the advection-diffusion equation. The dispersion processes are eventually replicated with the proposed approach on the remaining scenarios that the artificial neural network has never encountered. Provided with detailed meteorological field data, the cellular automata model could calculate the gas dispersion process about 1.5 times faster than FDS. As to the model performance, in the long term evolution, decreases in model accuracy are observed due to the nature of cellular automata in explicit evolution and the unavailability of error compensation methods. The transition rule that takes source terms into consideration outperforms in estimating the concentration distributions. [ABSTRACT FROM AUTHOR]

Accidental dust explosions pose a threat to people and property in industries that produce, process, handle or transport combustible dusts. Over the last century, the international research community has made significant progress towards better understanding of the dust explosion phenomenon. These efforts have contributed to the development of improved standards and best practice guidelines for safe design and operation of process facilities. Results obtained with advanced consequence models demonstrate the potential for applying such tools to the design and optimization of process facilities and equipment for explosion protection. It is foreseen that further development of numerical methods will include improved representation of particle-laden flows and combustion. It is essential that safety engineers acknowledge the inherent limitations and uncertainties associated with the collection of dust samples from industrial facilities, parameters determined in standardized tests, and the extrapolation of results from laboratory experiments to accidental explosion scenarios in industry. This paper reviews some of the practical aspects associated with risk assessments and risk management for dust explosions in the process industries, with emphasis on consequence modeling. The discussion outlines prospects for further development of test methods and simulation tools for industrial dust explosions, and provides recommendations for safety engineers and researchers. [ABSTRACT FROM AUTHOR]

Background and Objective: Ethylene oxide (EO) is a very toxic and dangerous substance with a high potential for explosion and fire. Ethylene oxide units are among the most hazardous units in petrochemical industries. This study was designed to analyze and model the consequences of ethylene oxide storage tanks explosion in one of Iran’s petrochemical industries. Materials and Methods: In this study, the consequences of the ethylene oxide storage tanks explosion in a petrochemical industry was identified and analyzed. This study was conducted in 2017 using PHAST software version 6.54. For this study, two climate conditions including the first climate conditions (spring and summer) and the second climate conditions (autumn and winter) were considered. Results: The results of the modeling for the first and second climate conditions showed that there were possibility of severe damages due to the explosion consequences up to 204 and 256 meters, respectively. In addition, based on the criteria for assessing the consequences of accidents associated with damage levels, such as the explosion wave, the wind speed and direction due to the sudden release scenario and the numerical results related to the modeling, the consequence of this scenario in the second climate conditions (autumn and winter) was higher than the first climate conditions (spring and summer). Conclusion: The findings of the study indicated that, in addition to the high risk of explosion of ethylene oxide storage tanks, the modeling scenarios in different climate conditions have different consequences. Thus, more attention should be paid to safety of these equipment as risk centers in the petrochemical industry and similar industries. [ABSTRACT FROM AUTHOR]

Chlorine and its compounds are widely used in industries and they are needed to produce lots of materials. This element that is abundant in the Earthâs crust and oceans, the powerful, corrosive substance is considered essential to an array of products. Thus, these chemicals could be causing catastrophic events. It should be noted that in the United States, It is second only to carbon monoxide when it comes to the percentage of accidents that cause injuries. One of the important recent efforts that were carried out was Jack Rabbit field experiment. It was organized in order to generate essential data to improve estimations of consequences of dense gas releases like chlorine and ammonia. It took place in 2010 at Dugway Proving Ground, Utah, USA. In this paper, chlorine release from the tank in this trial has been modeled and also health and safety effects have been evaluated. Hazardous areas, the width of the cloud and probability of fatality in several areas are the results of modeling. Also a good conformity between experimental results and model outputs could be observed.

This article presents a new model for the initial dispersion phase of energetic instantaneous expansion following a catastrophic vessel rupture. This model has been implemented as a new sub-model in the Phast dispersion model and is based on more sound physical principles than the old Phast sub-model. It allows for both vapor and two-phase releases. In the case of two-phase releases, droplets are assumed to expand radially, potentially leading to time-varying droplet rainout and the formation of a spreading evaporating liquid pool. For ground-level vapor or two-phase releases the correctness of the numerical predictions is confirmed against an analytical solution. The model has been validated against previously published experimental data for pressurized releases with and without rainout. This includes ground-level releases for nitrogen vapor and flashing liquid propylene, and elevated flashing liquid releases for Freon 11, Freon 12, propane and butane. Overall the old model tends to under-predict the cloud radius and cloud speed versus time, while the new model more closely agrees with small-scale experimental data. Therefore the new model produces smaller concentrations and doses, and is less conservative. For two-phase releases the new model predicts an increased amount of rainout, which is more in line with the experimental data. © 2017 American Institute of Chemical Engineers Process Saf Prog 36: 307-313, 2017 [ABSTRACT FROM AUTHOR]

Background and aims: One of the most essential and important steps for improving safety level in existing or designing units is consequence evaluation of hazards such as fire, explosion and dispersion of hazardous chemical substances. Due to severe operational conditions, high explosive and flammable gases such as methane and hydrogen, hydrogen production process is causing major industrial accidents of the view life and financial losses. Therefore safety is main concern of hydrogen producers. Methods: First, all hazards and potential scenarios of hydrogen production were identified by applying HAZID Technique, and after collecting the required data, consequence modeling was done by means of professional software PHAST6.54. Death probability of people by means of valid equations of probit was calculated and ultimately, the severity of the consequences was estimated using conventional criteria . Results: The results revealed that, jet fire caused by a full bore rupture in Desulphurization reactor has the highest fatality (26person). The harm effect distance, maximum radiations of this incident were 250 m, 370 kW/m2 respectively. A full bore rupture in Reformer can lead to the most dangerous flash fire. So that people at distance up 130 m from placing leakage and affected area 1505m2 were exposed to concentration of 61120 ppm and all people would be killed. The most dangerous vapor cloud explosion caused by hydrogen purification absorbers, so that distances up to 60m from absorbers location all people would be killed and all process equipments and buildings will be completely destroyed. The safe distance of hydrogen production unit equals to 746 m from its boundary limit. Conclusion: Consequence evaluation is a quantitative and comprehensive method for estimation and evaluation of potential incidents severity of industrial hazardous units. The occurrence of incidents such as fires and explosions has the great life and financial losses in the hydrogen production process, Thus safety of industries nearby hydrogen production and consume must be specifically considered .

Introduction: using fossil fuels, some hazards such as explosion and fire are probable. This study was aimed to consequence modeling of fire on Methane storage tanks in a gas refinery using analyzing the risk, and modeling and evaluating the related consequences. Method: Hazard analysis by PHA was used to choosing the worst-case scenario. Then, causes of the scenario were determined by FTA. After that, consequence modeling by the PHAST software was applied for the consequence analysis. Results: Based on some criteria, the fire of methane gas tank (V-100) was selected as the worst-case scenario at the refinery. The qualitative fault tree showed three factors including mechanical, process, and human failures contribute in gas leakage. The leakage size and weather conditions were effective on the distance of radiation. Using consequence modeling, thermal radiation was considered as the major outcome of the incident. Finally, for outcome evaluating, probit equations were used to quantify losses and the percentage of fatalities due to the methane gas leakage and fire occurrence. The maximum number of fatalities caused by fire was obtained 23 persons. Conclusions: In conclusion, the methane gas vessel in the refinery can be considered as the main center of hazard, therefore the implementation of the safety rules, eliminating mechanical failures, personal protection and education, and Effective measures to prevent and fighting of fire are proposed for decreasing the probable losses and fatalities.

One challenge in accounting for process safety incidents is that accurate modeling is complex, time-intensive, and requires many inputs. Process safety consequence modeling using first principles can be complicated. At the same time, setting up experiments is not always practical. This work proposes an artificial neural network (ANN) framework to predict process safety metrics to prevent overpressure during tube rupture scenarios with reasonable accuracy. Specifically, we apply a feed forward neural network to predict heat exchanger safety rating that is proportional to the heat exchanger pressure normalized with respect to the maximum allowable pressure. By training ANN to a set of tube rupture simulation data, we are able to bypasses the need for solving tedious dynamic and non-smooth system of equations. The ANN-based models yield safety rating predictions that comply with API 521 overpressure standards. We further demonstrate how these predictions can be used to perform real-time monitoring for a network of heat exchangers in a plant setting. • ANN framework introduced for detecting overpressure severity in heat exchangers. • Detailed algorithm serves as basis for consequence modeling predictions. • Single high fidelity and generalized safety rating predictions models were developed. • ANN models successfully bypassed rigorous dynamic overpressure models. • Real-time overpressure monitoring demonstrated for heat exchanger network. [ABSTRACT FROM AUTHOR]

The economic viability of industrial processes strongly depends on their safe and reliable operation. The method of inherent safe process design enables systematic consideration of safety measures in order to ensure process safe operation at the early stages of process design. The challenge is that the economic measures that are often considered for the design of industrial processes are often incommensurable with the safety measures. In the present research, a novel framework is proposed in which the safety criteria are quantified based on consequence modeling and aggregated with the economic performance using multi-objective optimization programming. The developed methodology was applied to the design of a simple refrigeration cycle. The optimization algorithm was NSGA-II. The results suggested a strong trade-off between the competing economic and safety objectives in terms of Pareto frontiers that clearly quantified the required compromise. It was observed that only with a minor increase in the capital investment, it is possible to significantly improve the safety. While the case of the refrigeration cycle was selected as a demonstrating case, the research methodology is to large extend general and deemed to be acceptable to design and operation of other industrial processes. [ABSTRACT FROM AUTHOR]

Introduction: As a consequence of using fossil fuels, some hazards such as explosion and fire are probable. This study was aimed towards consequence modeling of fire on methane storage tanks in a gas refinery using risk analysis, as well as modeling and evaluating the related consequences. Methods: Hazard analysis by PHA was used to choose the worst case scenario. Then, causes of the scenario were determined by FTA. After that, consequence modeling by the PHAST software was applied for consequence analysis. Results: Based on some criteria, the fire of methane gas tank (V-100) was selected as the worst case scenario at the refinery. The qualitative fault tree showed three factors including mechanical, process, and human failure contributing in gas leakage. The leakage size and weather conditions were effective on the distance of radiation. Using consequence modeling, thermal radiation was considered as the major outcome of the incident. Finally, for outcome evaluation, probit equations were used to quantify losses and the percentage of fatalities due to methane gas leakage and fire occurrence. The maximum number of fatalities caused by fire was obtained as 23 persons. Conclusions: In conclusion, the methane gas vessel in a refinery can be considered as the main center of hazard; therefore, the implementation of safety rules, eliminating mechanical failures, personal protection and education, and effective measures to prevent and fight fire are proposed for decreasing the probable losses and fatalities. [ABSTRACT FROM AUTHOR]

Natural gas is odorized at city gate stations in order to make gas leaks detectable and consequently to protect consumers against the hazardous properties of natural gas. Small concentrations of organic sulfur compounds are used as gas odorants because of their inherent penetrating smell. These compounds are mostly toxic and flammable. In this paper, possible failures of odorizing system are studied and consequences of probable hazardous accidents are evaluated. Catastrophic rupture of the odorizer tank is selected as the worst case scenario. Further-more, necessary information for simulating the scenario, including physical, chemical and thermodynamic properties of the odorant, technical information and normal working conditions of the tank as well as topographical and meteorological conditions of the station is collected from reliable sources. In order to consider all meteorological conditions in which accidents may occur; warm, very hot, cool, very cold and windy conditions are defined. The hazardous consequences due to tank catastrophic rupture are simulated by PHAST software and results are analyzed by an expert team. For the selected scenario, two hazard categories are discussed as toxic gas dispersion and fire. According to the definition of ERPG-1 (Emergency Response Planning Guidebook) people in nearby inhabited areas won't experience major harms due to short exposure time, though toxic gas concentration is within the health threatening range. On the other side, flash fire effect zone encompasses the unit area and nearby farm lands and may lead to severe damages. [ABSTRACT FROM AUTHOR]

Designing the process layout in a chemical plant is a complex and multidisciplinary task requiring input from experts in fields such as chemical, civil, mechanical, and instrument engineering. Plant layout entails the allocation of a given number of facilities on a given piece of land. Determining the optimal distribution of facilities in a plant requires an optimization calculation, including a variety of distance constraints, one of which is related to process safety. A few approaches have been taken to transform consequence analysis, such as toxic gas dispersion and its mitigation as well as the risks of fire and explosions, into mathematical equations as constraints of an optimization problem. An optimization problem with constraints related to safety is not easy to solve given limitations such as nonlinearity, uncertainty, and ethical difficulties in converting human life to costs for calculation purposes. However, safety concerns have increased to the point that developing this type of approach is necessary. The objective of this study was to review the current methodologies for plant layout optimization and to resolve facility siting issues. Process safety concepts are considered with a view to identifying gaps and issues with current methods in order to develop better methodologies for designing safer layouts. [ABSTRACT FROM AUTHOR]

Background: The present study aimed to consequence modeling and root cause analysis of the real explosion of a methane pressure vessel in separation unit of a gas refinery in Iran., Method: ology: This study was performed in a gas refinery in the south of Iran. The studied scenario was the actual scenario that occurred in the studied pressure vessel. Modeling of possible consequences was performed using PHAST 7.2 software. Also, the root causes analysis of the accident was performed using experts' brainstorming., Results: At radii of 15 and 45 m, the radiation level reaches 12.5 and 4 kW/m 2 , respectively. In the late explosion worst-case, the vapor cloud explodes after reaching a distance of 20 m from the pressure vessel. At radii of 20 m, 25 m, and 150 m from the center of the explosion, the pressure reaches 0.2068, 0.1379, and 0.02068 bar, respectively. In the Early Explosion Overpressure, the acceptable pressure is obtained at a distance of 193 m. Moreover, in the Early Explosion Overpressure radiation, at radii of 28 m, 38 m, and 193 m, the pressure reaches 0.2068, 0.1379, and 0.02068 bar, respectively., Conclusion: The findings revealed that creating an appropriate risk management algorithm with a focus on consequence modeling can be an effective step towards reducing losses in the process industry. This results can create a novel insight in comparing the two reactive and proactive approaches and also reveal the effectiveness of consequence modeling in reducing the severity of risks., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (©2023PublishedbyElsevierLtd.)

Analytical models and the prediction of accidents and their consequences are important tools for preventing accidents in the industry. Therefore, the present study was conducted to review process accident consequence modeling in Iran (2006-2022), helping improve incident modeling, and creating a context for preventing these accidents. In this study, the articles of 5 international Embase Medline/PubMed databases, ProQuest, Scopus, Google Scholar, and Web of Science, and four Iranian databases SID, MagIran, IranMedex, and IranDoc were examined using the PRISMA checklist. After reviewing the studies, 40 articles were included in the final analysis. The results showed that 25 studies used PHAST software, 11 studies used ALOHA software and 4 studies used ALOHA and PHAST software together. The highest number of studies was conducted in Imam Khomeini Port and Asaluyeh city, respectively. In addition, the number of studies published in Persian was more than in other studies. There was no similar agreement between the results of the two software in providing correct results at low concentrations. PHAST software also provided more accurate results than ALOHA over longer distances in stable and relatively stable weather conditions. The study and identification of hazards and scenarios in the studies that used PHAST software were more, more accurate and more coherent than in the studies that used ALOHA software. It is suggested that in future studies the same scenario can be compared with PHAST, ALOHA, and newer modeling software such as Fire Dynamics Simulator (FDS)., Competing Interests: The authors declare no conflict of interest., (© 2023 The Authors. Published by Elsevier Ltd.)

The main objectives of any drilling companies are drilling safely, providing usable well completion and minimizing costs. Among all, health, safety and environment (HSE) consideration supersedes. Also, oil and gas well-drilling industry is an industry with high level of risks concerning HSE. Not only does each factor of these risks need to be analyzed but also need to be adjusted by the appropriate risk modeling. This project is assigned to model risk and consequence assessment for some aspects of blowout. The consequences should be formulated but require some adjustment. Proper Delphi group for risk assessment is made to localized risk factors. As there is uncertainty during data collection, the fuzzy approach is used. Finally, prioritizing the assets according to their criticality demonstrate significance of the risk. In the case study, the blowout in onshore Iranian drilling industry is studied. The results show that the risk of blowouts according to the reason of shallow gas in exploration well is the highest. Human failure, attack, natural event, lost circulation in development well and human failure in workover well, are another risks for Iranian drilling industry, respectively. [ABSTRACT FROM AUTHOR]

There are different well-established strategies for making a process plant inherently safer. The benefits of applying these strategies on reducing the overall risk inside a plant are obvious. However, some of these changes are rejected many times because they appear to be too costly. But if the effects of applying inherently safer design strategies are investigated not only on the processing costs of a plant but also on the potential accident costs, the decision would in fact be different. In this paper an optimization procedure is proposed which integrates both processing and accident costs for different design schemes. In this procedure, some of the design variables are chosen with regard to inherently safer design strategies. The objective function is the sum of accident costs and plant lifecycle processing costs. For assessing accident costs, consequence modeling techniques and probit functions are applied. Consequence modeling formulas and an objective function are codified in an optimizer package (MATLAB) and to accomplish the optimization process a process simulator (called HYSYS) is coupled with this package. The application of the proposed procedure is demonstrated by selecting an optimum process scheme for a Refrigeration plant as a case study. [ABSTRACT FROM AUTHOR]

Abstract: Cryogenic compressed hydrogen tank may open new possibilities for onboard storage due to its high energy density and acceptable thermal endurance. As promising hydrogen storage for commercial use, its hazards need comprehensive investigation. This paper studies the consequences of accidental hydrogen releases from cryo-compressed storage and evaluates the cold effects, thermal effects, and overpressure and missile effects. Two typical storage conditions for a fuel cell car are considered, including driving condition and quasi-venting condition after a long-term of parking. Results show that flash fire and vapor cloud explosion can be considered as the leading consequences. Without ignition, catastrophic rupture may be more dangerous than leakages but with ignition the results may vary for different release diameters. For leakages, quasi-venting condition may be more dangerous than driving condition. However, for catastrophic rupture, the results may be not uniformed but depend on whether and when the hydrogen is ignited. Moreover, the influences of wind velocity and atmospheric pressure are also investigated. [Copyright &y& Elsevier]

The authors were asked to assist a utility with a risk management decision. Specifically, the utility was considering whether they should maintain or decommission an 800,000 gallon propane storage sphere. The 30-year old sphere was the fuel storage vessel for a propane standby system. One of their major concerns was the shrinking buffer zone around their facility. Although the facility was originally located in a remote rural area, residential development had begun to encroach upon the facility's buffer zone. The original analysis was based on a consideration of the offsite consequences for a worst-case scenario. This was done at the request of the client as it reflected their degree of risk acceptance. The consequences of two hazard scenarios were analyzed: an unconfined vapor cloud explosion and a Boiling Liquid Expanding Vapor Explosion (BLEVE). To support this analysis, the mechanical integrity of the sphere was evaluated deterministically by considering the pressure vessel design documents, the limited nondestructive test and evaluation data available, and published data on typical corrosion rates. Additional factors incorporated into the analysis were the capabilities of the existing fire protection system, the facility security system, and the propane unloading station for tank car deliveries. Finally, the economics of maintaining the sphere versus decommissioning it were explored. Ultimately, the utility decided to decommission the sphere. In this article, we conduct a retrospective study using a risk-based approach. We identify a set of hazard scenarios for the propane storage sphere, calculate the leak frequency for each scenario, compute the associated source term, and evaluate the consequences. The results are compared with the original consequence analysis and other published hazard studies. The implications for risk management are discussed. © 2013 American Institute of Chemical Engineers Process Saf Prog, 2013 [ABSTRACT FROM AUTHOR]

Abstract: The accidental releases of hydrogen from liquid storage and the subsequent consequences are studied from a harm perspective rather than a standpoint of risk. The cold, thermal and overpressure effects from hydrogen cold cloud, fireball, jet fire, flash fire, and vapor cloud explosion are evaluated in terms of two kinds of effect distances based on lethal and harmful criteria. Results show that for instantaneous release, the sequence of effect distances is vapor cloud explosion > flash fire > cold cloud > fireball, and for continuous release, the sequence is vapor cloud explosion > flash fire > jet fire > cold cloud. An overall comparison between instantaneous and continuous release reveals that the catastrophic rupture, rather than leakages, is the dominant event. Besides, the effect distances of liquid hydrogen tank are compared with those of 70 MPa gaseous storage with equivalent mass. Compared with 70 MPa gaseous storage, the liquid hydrogen storage may be safer under leak scenarios but more dangerous under catastrophic rupture scenario. [Copyright &y& Elsevier]

Abstract: With the development of large-scale fell cell vehicle demonstration project worldwide, the global number of hydrogen refueling stations has increased rapidly in recent years. The external safety of hydrogen refueling stations has always been a public concern for its further development. This paper examines the harm effect distances of severe accidents for a gaseous hydrogen refueling station. First, different accident scenarios are assumed and their subsequent consequences are calculated, including physical explosion, jet fire, flash fire and confined vapor cloud explosion. Results show that physical explosion and worst case of confined vapor cloud explosion produce the longest harm effect distances for instantaneous release and continuous release, respectively. This indicates that they may be used as decisive consequences to the determination of safe distances. Second, the influences of different factors on harm effect distances are investigated, including those of release inventory, release pressure, release height, release angle, release diameter and wind velocity. Then, based on these results, several potential hazard mitigation measures are proposed such as elevating hydrogen equipment, using smaller vessel and adopting smaller pipe work, if reasonably practicable. [Copyright &y& Elsevier]

We have developed a simulation model to quantify and characterize the response of the public health system and the impact of public health advisories in the event of an intentional contamination of the food supply. The model has three components: (1) definition of individual exposure over time and the outcomes of exposure, (2) definition of the geographical dispersal of exposures, and (3) response of the public health authorities to symptomatic individuals. The model explicitly considers the variation in the multiple interrelated facets of the response system, including differences among individuals' responses to exposure, variation between health care providers, and the subsequent processing of samples and confirmation of cases. To illustrate use of the model, case studies with Escherichia coli O157:H7 and Salmonella spp. in three categories of food vehicle were compared. The level of detail required to run the public health component of the model is not trivial. While some data may not be available for hazards of particular interest in potential bioterrorism events, the application of expert judgment permits comparisons between different agents, different system reactions, and other assumptions within the system. The model provides the capacity to study the impact of system changes, to compare scenarios and to quantify the benefits of improvement in terms of averted exposures and risk reduction, and constitutes a significant aid to understanding and managing these threats. Essentially, the model provides an explicit valuation of time saved in the identification and intervention in terrorist events in the food supply. [ABSTRACT FROM AUTHOR]

Abstract: Risk assessment in chemical process industry is a very important issue for safeguarding human and the ecosystem from damages caused to them. Consequence assessment is an integral part of risk assessment. However, the commonly used consequence estimation methods involve time-consuming complex mathematical models and simple assimilation of losses without considering all the consequence factors. This lead to the deterioration of quality of estimated risk value. So, the consequence modeling has to be performed in detail considering all major losses with optimal time to improve the decisive value of risk. The losses can be broadly categorized into production loss, assets loss, human health and safety loss, and environment loss. In this paper, a conceptual framework is developed to assess the overall consequence considering all the important components of major losses. Secondly, a methodology is developed for the calculation of all the major losses, which are normalized to yield the overall consequence. Finally, as an illustration, the proposed methodology is applied to a case study plant involving benzene extraction. The case study result using the proposed consequence assessment scheme is compared with that from the existing methodologies. [Copyright &y& Elsevier]

Liquefied natural gas (LNG) project modeling focuses on two primary issues, facility siting and the physical layout of element spacing. Modeling often begins with an analysis of these issues, while ensuring code compliance and sound engineering practice. The most commonly performed analysis involves verifying compliance with the siting provisions of NFPA 59A, which primarily concern property-line spacing (offsite hazard impacts). If the facility is located in the US, compliance with 49 CFR 193 is also required. Other consequence modeling is often performed to determine the spacing of elements within the facility (onsite hazard impacts). Often, many issues concerning in-plant spacing are addressed with the guidance provided in Europe''s LNG standard, EN-1473. Spacing of plant buildings in relation to process areas is also a concern as analyzed using the approach given in API RP 752. Studies may also include probabilistic analysis, depending on the perceived risk and cost of mitigation. [Copyright &y& Elsevier]

Ammonia is a toxic compound and has many toxic effects on humans and the environment. This study was designed to model the consequences of ammonia leakage in an industrial slaughterhouse. Given the potential hazard of ammonia, only the toxic dimension of this gas was evaluated. The scenarios were evaluated in the worst possible condition and in the case of the complete rupture. Findings showed that in case of a catastrophic rupture scenario in reservoir 1 in the first and second 6 months of the year, the distances of 920.37 and 569.38 m from the reservoir in the wind direction were at Emergency Response Planning Guidelines, level 3 (ERPG3), respectively. In reservoir 2, in the first and second 6 months of the year, the distances of 699.58 and 384.86 m from the reservoir were at the ERPG3 level, respectively. In reservoir 3, in the first and second 6 months of the year, the distances of 203.48 and 748.28 m from the reservoir were at the ERPG3 level, respectively. Examination of the probit values showed that in reservoirs 1 and 2, the probit values were more than 4.28 up to 100 m from the reservoirs, and in the reservoir 3, the mortality rates were lower. The findings revealed that the catastrophic rupture of ammonia reservoirs in the studied slaughterhouse and the release of ammonia could lead to the fatality of large numbers of people in ERPG2 and ERPG3 areas. Therefore, it is necessary to take control measures to reduce the vulnerability against such accidents., Competing Interests: None