Risk Acceptance Criteria Research Articles

Quantitative Risk Assessment of an Oil-Gas-Hydrogen-Electricity Integrated Energy Station in China.

This paper presents a quantitative risk assessment (QRA) study of an oil-gas-hydrogen-electricity integrated energy station in China. A comprehensive assessment of the station was made in terms of consequences and risks, respectively. Consequence analysis shows that the severity of hazardous chemical leakage accidents in the station is in the order of natural gas, hydrogen, gasoline, and diesel fuel, especially in the liquefied natural gas (LNG) and compressed natural gas (CNG) storage tank areas, which may cause major accidents in the event of leakage. The results of the risk assessment showed that the individual and societal risks of the integrated oil-gas-hydrogen-electricity energy station exceeded the risk acceptance criteria. Moreover, the catastrophic rupture of LNG and CNG storage tanks is the main cause of the unacceptable risk. Additional mitigation measures for them, mainly including the installation of emergency manual shut-off valves, the installation of combustible gas detection and alarm devices, and pressure relief protection devices, can effectively reduce the risk to an acceptable level.

Modernisation of Domestic Ro-Ro Passenger Ships Operating in the Philippines

This paper forms part of a wider study in the form of a Formal Safety Assessment of the domestic passenger ships operating in the Philippines, undertaken on behalf of the Philippines Government, and financed by the World Bank and the International Maritime Organisation. The paper focuses on design deficiencies of the domestic RoPax ships, primarily in damage stability. The process of ship selection for representation of the wider fleet risk assessment is explained, leading to one medium RoPax and one large RoPax, typical of some 500 of these ships, serving the open sea domestic trade in the Philippines. To this end, the selected designs have been subjected to a systematic process of damage stability and flooding risk analysis in order to identify design vulnerabilities, leading to risk estimation in the form of Potential Loss of Life. A number of risk control options have then been identified, enabling a thorough risk assessment and identification of cost effective RCOs, as well as impact assessment, using IMO risk acceptance criteria as basis. Despite the poor state of the domestic Ro-Ro passenger vessels operating in the Philippines, many of these aged, badly retrofitted, poorly maintained, and operated, it has been possible to identify cost-effective design solutions to raise the damage stability (and safety) standard of these ships to international standards of newly designed ships; it seems an unprecedented achievement, but evidently true. This presents the Philippine Government and the owners of these vessels with a unique opportunity to upgrade their domestic fleet of RoPax vessels and showcase these against the best in the world. Because of the similarity in the approach, the selection of risk control options and the overall analysis adopted, only one of the typical RoPax vessels selected is presented in this paper.

Evaluation of reliability of complex engineering systems using risk acceptance criteria

The reliability evaluation of gas pipeline systems is one of the most important tasks, since the safety of gas supplies determines the reliable operation of the whole system.Purpose: This paper presents the evaluation methodology based on the risk acceptance criteria established in accordance with the current rules and standards.Methodology: A three-component methodology is used to evaluate the reliability level of gas pipeline systems. It is implemented by creating a model of failure consequences, which accounts for environmental conditions and pipeline properties. Acceptable probabilities of the pipeline failure are determined using the risk theory. Based on these data, the model is designed to assess the gas transport reliability in the pipeline system with regard to failure probabilities and hydraulic characteristics.Research findings: The reliability level of the system is determined using the acceptable failure probability. The obtained reliability is compared with that of the real pipeline system. The best procedure is proposed to maintain and improve the system reliability.

Методические подходы к расчету показателей риска аварий при обосновании безопасности размещения магистральных газопроводов в пределах пятой подзоны приаэродромной территории

The issues of safe allocation of hazardous production facilities, particularly trunk gas pipelines and gas supply facilities, as well as the application of a risk-oriented approach with the substantiation of such allocation, are currently at the top of the agenda. The article continues the earlier published studies dedicated to the review of quantitative and qualitative approaches to the risk analysis of the field, the determination of acceptable risk criteria with the substantiation of safe allocation of trunk gas pipelines and gas supply facilities within the fifth subzone of the aerodrome environs. The study provides general relations for the calculation of risk indices; the final calculated indices are the individual risks of fatalities among passengers and crewmembers as well as the annual number of fatalities on aircraft as a result of accidents at hazardous production facilities per 1 million persons of passenger traffic. The suggested approach takes into account several aviation-specific factors; i.e., aircraft flights at variable heights, complex configuration of take-off and landing, several available routes of approach to the airport (departure from the airport), and random allocation of hazardous production facilities adjacent to the aerodrome. A methodology and algorithm to use the introduced general relations have been provided, for which lists of input data and basic assumptions have been composed. The assumptions enable the conversion of general relations into simple algebraic expressions. Safety criteria and methodological approaches to determine their actual values, as suggested by the authors, enable linking the field of industrial safety and the field of aircraft flight safety and primarily aim at the reduction of uncertainties associated with problems of risk-oriented approach with the substantiation of allocation of trunk gas pipelines within the fifth subzone of the aerodrome environs. The vectors of further improvement of the methodology have been proposed.

The need for nonuniform risk acceptability across climate change scenarios.

Climate change risk assessment studies focus on identifying and analyzing different risks considering several climate change scenarios and on evaluating the cost-effectiveness of different adaptation measures. However, risk acceptability is often not reflected on in the context of climate change risk studies. Noting that the different climate change scenarios depict drastically contrasting images of the future in terms of population growth, economic development, and changes to life expectancy, this article uses risk acceptance criteria that are based on socioeconomic considerations to highlight the need for nonuniform risk acceptability across climate change scenarios. For this purpose, the optimum implied cost of averting a fatality derived based on the life quality index concept and the value of a quality-adjusted life year derived based on the time principle of acceptable life risk are assessed in three different climate change scenarios for Sweden. Additionally, an illustrative example that assesses the acceptable probability of failure of a steel rod under axial tension in the different climate change scenarios is presented. It is shown that risk acceptance criteria can vary considerably across the different climate change scenarios (e.g., more than 190% variation in the acceptable probability of failure for Sweden in the considered example). This article demonstrates that the ability of societies to afford risk-reducing measures may vary considerably across the different climate change scenarios. Hence, it can be concluded that (1) in the context of climate change risk assessments, risk acceptance criteria need to be developed to account for the different climate change scenarios, and (2) these criteria may vary considerably across the different climate change scenarios. Finally, relevant challenges and research needs are also provided.

Assessing Risk Acceptability and Tolerability in Italian Tunnels with the Quantum Gu@larp Model.

Road tunnels are associated with numerous risks including traffic accidents and fires, posing threats to individual or group users. Key risk indicators such as Risk Quantum, Individual Risk, Societal Risk, and Expected Number of Fatalities are instrumental in evaluating the level of risk exposure. These indicators empower Rights-Holders and Duty-Holders to report hazards, prevent disasters, and implement timely remedial measures. A crucial indicator, the Scenario Risk Quantum, has its roots in the forensic evaluation of responsibility in a fatal tunnel accident in the UK since 1949. The Quantum of Risk of each design scenario, reasonably selected among rational and practicable possibilities, has both a deterministic and probabilistic character. The Risk Tolerability and Acceptability criteria are modelled according to risk indicators by selecting the parameters according to ethical principles and societal policy. Scenarios are meticulously identified, described, probabilised and assigned probabilities prior to the quantitative risk analysis. These risk indicators are integral to the risk assessment process. This article delves into the understanding of these indicators within the context of Italian road tunnels, employing the Quantum Gu@larp Model to analyse Risk Acceptability and Tolerability.

Risk-based path planning for preventing collisions and groundings of maritime autonomous surface ships

In this paper, we propose and demonstrate a method for risk-based path planning, generating risk-acceptable trajectories for an autonomous surface ship. This objective is achieved in two steps. The first step uses a dynamic probabilistic risk assessment method called K-shortest-paths Probabilistic Risk Assessment (KPRA), alongside risk models and dynamic system simulation, whose output is a list of paths ranked with respect to risk. Multiple risk influencing factors and accident types may be considered in this step. In this work, collision and powered grounding accidents, and their risk-influencing factors and indicators, are considered. The second step is to perform risk evaluation on the ranked scenarios, comparing them to predefined risk acceptance criteria and defining which scenarios have acceptable risk. Evaluating multiple paths allows operators to choose how strict the autonomous ship’s decision-making should be regarding risk, avoiding the problem of minimization algorithms being too conservative in terms of risk. One of the risk-acceptable paths is then chosen as a local plan to be acted by the autonomous ship. This paper has two main scientific contributions. First, an online Bayesian belief network risk model for navigation accident probability is designed and integrated to improve KPRA. Second, we propose a modified guidance, navigation, and control framework for autonomous ships, to include risk-based planning. We implement the modified framework into a real autonomous surface vehicle (ASV) named Grethe and demonstrate the method’s capabilities in field trials, where the ASV uses the method to generate local plans that avoid possible collision and grounding accidents.

A methodology to determine the target reliability of natural gas pipeline systems based on risk acceptance criteria of pipelines

The reliable operation of the natural gas pipeline system is directly related to natural gas supply security, and it is vital to determine the target reliability of the natural gas pipeline system when assessing whether the system is reliable. In this study, a methodology to determine the target reliability of natural gas pipeline system based on the risk acceptance criteria of pipelines is proposed, and the methodology consists of three parts. Firstly, the risk acceptance criteria of the natural gas pipelines are determined based on the existing standards. Secondly, the failure consequence model of natural gas pipelines considering the pipeline properties and surroundings is developed, and the corresponding allowable pipeline failure probabilities are calculated according to the risk theory. Finally, the evaluation model of the gas supply reliability for natural gas pipeline systems considering the unit’s failure and hydraulic characteristics is developed, and the target reliability of natural gas pipeline systems is calculated by employing the allowable pipeline failure probabilities. Furthermore, a real natural gas pipeline system is employed to determine its target reliability, and the target value is compared with the actual value of the gas supply reliability. Based on the compared results, the corresponding measure to improve the gas supply reliability is proposed.

Towards system-theoretic risk management for maritime transportation systems: A case study of the yangtze river estuary

This paper presents a novel framework for system-theoretic risk management of maritime transportation systems (MTS) based on the principles of formal safety assessment. The proposed framework comprises four essential steps: (1) risk identification: identifying accident scenarios and associated risk-influencing factors in the MTS through text mining of maritime accident investigation reports; (2) risk analysis: determining the probabilities and consequences of accident scenarios in the MTS using Bayesian network modeling; (3) risk evaluation: assessing the risks of various accident scenarios and the comprehensive risk of the MTS, and comparing the results with risk acceptance criteria to make informed decisions; and (4) risk treatment: proposing effective risk control options (RCOs) for accident scenarios and the comprehensive risk of the MTS by incorporating expert judgment, fuzzy sets, and Bayesian network modeling. To demonstrate the applicability of the proposed framework, the risk management of the Yangtze River Estuary is presented as a case study. By adopting a comprehensive approach to risk management, stakeholders gain a more holistic view of risk and achieve more effective decision-making processes for RCOs. The framework may help improve the safety and security of maritime operations, enhance the efficiency and competitiveness of the industry.

Quantitative risk assessment of China's first liquid hydrogen refueling station.

Hydrogen refueling stations (HRSs) are among the most important infrastructures for fuel cell vehicles. However, the safety issue of HRSs has become a key constraint to the wide application and development of hydrogen energy. This article presents a quantitative risk assessment of the first liquid HRS (LHRS) in China and conducts a comprehensive assessment in terms of both individual (IR) and societal risks (SRs). The results showed that both the IRs and SRs related to the LHRS exceeded the risk acceptance criteria. The rupture of the flexible hose of the dispenser and the leak from the compressor are the main contributors to these risks. On the other hand, implementing appropriate mitigation measures on the level of the LHRS dispenser and compressor, including the addition of breakaway couplings in the flexible hose of the dispenser, the installation of hydrogen detection sensors, the arrangement of automatic and manual emergency shutdown buttons, and the elevation of the compressor, is capable of reducing the risk of the LHRS to be within the risk acceptance criteria.

Perception on landslide risk in Malaysia: A comparison between communities and experts' surveys

Surveys and interviews were conducted in the present study among the public and landslide experts from various sectors in Malaysia to study their perception towards landslide risk in the country. Utilizing a questionnaire survey and interviews can prove valuable in determining acceptable risk criteria for landslides by collecting opinions from both the communities and experts. The demographic factors that govern frequency of acceptability, insurance premium purchase etc. were determined through the independent sample t-test, one-way analysis of variance, and Brown–Forsythe test. Most non-experts expressed the lowest acceptance in landslide risk for all scenarios (from low to high risk), whereas the experts were willing to accept a higher landslide risk as they understand that an ideal low landslide risk environment is not feasible at the current Malaysian scenario. Gender, occupation, and level of education were the significant demographic factors influencing the landslide risk acceptability in Malaysia. Key factors to consider when developing risk evaluation criteria and shortcomings of the previous proposed risk criterion for Malaysia were discussed. Modifications were proposed to the existing landslide risk criterion with a lower acceptance towards death upon taking into consideration findings from the present study. While the new landslide risk criteria were specifically formulated for the socio-economic-political environment of Malaysia, the same approach can be customized for different societies and types of hazards. The authors also believed that this endeavour would result in more logical and uniform decision-making processes, ultimately leading to the preservation of lives and resources in regions prone to landslides worldwide.

Using a Proposed Risk Computation Procedure and Bow-Tie Diagram as a Method for Maritime Security Assessment

Terrorism, piracy, robbery, and cyber-threats on ships and at port facilities, as well as smuggling and drug trafficking through cargo and containers, are some of the international security problems for which national maritime security services must provide solutions. Cyber-attack is considered particularly important as it can be combined with all the other security vulnerabilities in the shipping industry. There is no extensive and in-depth literature for the risk acceptance criteria concerning maritime security. Basic information is drawn from other areas, such as civil aviation. It is necessary to standardize these criteria, as is the case with formal safety assessment, where practitioners know how to gather information, to make comparisons with previous experience, and to make decisions that are often based on experience from the past. The aim of the present study is to address the issue of maritime security through the development of a method applicable to the maritime industry that evaluates and manages maritime security-related risks. Security cost-benefit analysis and decision-making procedures will be required in the future. The proposed method uses the bow-tie diagram tool for the estimation of risk. A risk computation procedure is described after the application of a set of prevention barriers, which is based mainly on the accuracy of the definition of the probability and the contribution of each threat, as well as the accuracy of estimation of the effectiveness value of each prevention barrier for the same threat as defined by the user. Similarly, the risk computation for each consequence, after the application of a set of mitigation barriers, is based mainly on the accuracy of the definition of the risk value of each consequence as well as on the accuracy of the estimation of the effectiveness value of each mitigation barrier for the same consequence as defined by the user. The results of the risk computation appear in the bow-tie diagram providing a colored scheme of the risk values obtained for the top event and consequences after the introduction of the necessary prevention and mitigation barriers.Terrorism, piracy, robbery, cyber-threats, smuggling and drug trafficking etc., are some of the international security problems due to which the national maritime security services must provide solutions. There is no extensive literature for the risk acceptance criteria concerning maritime security and basic information is drawn from other areas. The aim of the proposed study is to develop a method applicable to the maritime industry that evaluates and manages maritime security related risks in a case of cyber-security. Security Cost-Benefit Analysis and Decision Making procedure will be required in the future. The proposed method uses the Bow-Tie diagram tool for the estimation of the risk. A risk computation procedure is described after the application of prevention barriers, which is based mainly on the accuracy of the definition of the Probability Pi and the Contribution Ci of each Threat ( i) as well as on the accuracy of the estimation of the Effectiveness value Eij, of each Prevention Barrier ( j) for the same defined Threat ( i), by the user. Similarly, the risk computation for each consequence, after the application of mitigation barriers, is based mainly on the accuracy of the definition of the Risk Value RVi of each Consequence ( i) as well as on the accuracy of the estimation of the Effectiveness value Eij, of each Mitigation Barrier ( j) for the same defined Consequence ( i), by the user. The results of the risk computation appear in the Bow-Tie diagram providing a coloured scheme of the obtained risk values for top event and consequences.

Update on Risk Criteria for Crude Oil Tanker Fleet

In recent years, the maritime trade of crude oil has suffered notable perturbations caused by the unbalanced relationship between supply and demand. The COVID-19 pandemic caused a drop in oil consumption in 2019, followed by a reduction in production in 2020. The seaborne transport of oil accounts for approximately 50–60% of all crude oil in world production. The crude oil market is a crucial regulator of the global economy and instabilities in this market have noticeable effects on collective risks. The immediate risks that the society see are the changes in the cost of living, which are followed by political uncertainties. Less visible are the risks that these uncertainties have on shipping companies and the level of management stability they have to maintain in order to keep seagoing safe. This paper presents an update on the overall state of risk management for the crude oil tanker fleet, evidenced by EMSA and other international marine organisations. The previous paper, entitled Safety Assessment of Crude Oil Tankers, which applied the methodology of the Formal Safety Assessment (FSA), was published in 2018 and covered the historical data related to the fleet size, accident reports, amount of oil spilled on sea and the economic value of the crude oil transport business. The particular focus of this paper is on the evolution of the risk acceptance criteria over the years and the difference in the predictions from 2018 to the present day. The effects of the pandemic on crude oil shipping are discussed through the changes in the risks. Three of them are analysed: PLL (potential loss of lives), PLC (potential loss of containment) and PLP (potential loss of property). The representation of the risk applies the F-N curves among the risk acceptance criteria lines observed for different tanker sizes. Among the three risks, the paper exposes the vulnerability of the loss of containment risk, where the strong economic impact of the oil trade outweighs the environmental concerns. In relation to the PLC, the paper proposes the approach of relating the oil spill acceptability with the spill quantity and ship revenue instead of to the cost of cleaning or the cost of environment recovery.

Occupational Risk Management in the Transport Company

Abstract The purpose of risk analysis is to provide a concrete basis for risk decisions that can be made as part of the risk management process in comparing the risk outcomes with risk acceptability criteria. The main objective of the occupational risk assessment presented in the paper is to provide employees with effective protection of the health and life of employees against hazards occurring in the work environment, as best as possible under specific conditions.

Assessment of Chemical Risks Associated with Hydrometeorological Phenomena in a Mexican Port on the Gulf of Mexico

Accidents in port areas in the Gulf of Mexico have had great economic costs, since this is an area exposed to extreme phenomena. Tropical cyclones or cold fronts, also known as Tehuantepecers, result in intense winds and waves that impact the coastal infrastructure. The chemical risk associated with extreme winds and waves for the fuel storage tanks of the facility of the Port of Veracruz, the main Mexican port in the Gulf of Mexico, was evaluated with a historical analysis of accidents as a tool to identify significant factors in disasters and establish risk acceptance criteria. It was found that the critical hazard threshold for Veracruz corresponds to winds stronger than 160 km/h (44 m/s) that may result in coastal waves of more than 5 m high. The vulnerability to these phenomena was calculated with the vulnerability index (VI), considering the structural, functional, and chemical factors in the infrastructure, including exposure levels. By means of a risk matrix, it was determined that gasoline storage tanks have a moderate chemical risk, since exposure to the extreme wind wave hazard is low, and diesel tanks are at low risk. These assessments are important elements to consider in the expansion plans for the Port of Veracruz.

Societal risk acceptance criteria of the global general cargo ships

The societal risk acceptance criteria (SRAC) are used in the shipping industry as a ruler to judge whether the actual ship risk is in control. To exploringly refresh SRAC for general cargo ship formulated by International Maritime Organization (IMO) in 2000, a comprehensive analysis was performed by using the accident data recorded in the Marine Casualties and Incidents (MCI) module of the Global Integrated Shipping Information System (GISIS) database from 2005 to 2019. The risk levels of four typical accident factors, including initial event, ship size, classification society, and geographical zone, were evaluated. The results illustrate that the SRAC established in this study for general cargo ship fatality accidents are found stricter than that by IMO presented in 2000. Fire/explosion and capsizing show the highest societal risk levels in the initial events, and large general cargo ships face higher societal risk. In addition, ships that do not belong to the International Association of Classification Societies (IACS) are at a higher risk than IACS ships. And the societal risk levels of fatality accidents in East & Southeast Asia and injury accidents in Europe, the Mediterranean & Black Sea are higher than those in the other zones.

Development of a risk informed quantitative decision making framework for major accident hazards installations in Sri Lanka

This paper proposes a risk informed decision-making framework for siting Major Accident Hazard Installations in Sri Lanka. It is named the “Upper Bound FN curve” method. Generic failure rate data are utilized as country specific data are not available. FN Curves are derived for each process node of a Major Accident Hazard Installation using different failure rate data sets available in literature. The data sets giving the “worst case” FN Curve for each process node is identified. These FN Curves are called the Upper Bound FN Curves. Using these curves, a composite FN Curve is developed which is compared against the country specific risk acceptance criterion line. If the risk is not acceptable, further safety barriers are introduced. Safety distances are then determined using a scaling factor developed in this study called the relative risk reduction factor (RRRF). The RRRF is determined based on the comparative position of the composite FN curve with respect to the criterion line. The proposed methodology was applied in a case study of liquefied propane storage tank. Guidelines for application of the proposed framework, interpretation of the “Upper Bound FN Curve” method and estimation of safety distances are presented.

Establishment of risk acceptance criteria using Life Quality Index: Application to the Indian context.

The formulation of risk acceptance criteria may be coupled gainfully with a prediction of the of investment required to comply with it, an exercise which can benefit from the application of socioeconomic indicators. The Life Quality Index (LQI) is one such indicator which amalgamates human mortality and wealth creation and places an implicit economic value on reduction of life risk. While there have been a number of studies to demonstrate the application of LQI pertaining to various technological systems, the present work extends it to estimate the sectoral level investment needed to reduce public risks to within the As Low As Reasonably Predictable region for the chemical industry, with specific illustration of the methodology for India. The potential reduction in public individual risk is computed as a function of percentage increase in safety investment expressed as a fraction of the industry's contribution to the nation's GDP. In addition, using a new, more accurate expression, estimates of a related parameter, the implied cost of averting a fatality (ICAF), are obtained for a number of developed economies and India. The ICAF estimates show reasonable agreement with the value of statistical life (VSL), a parameter which is integral to cost-benefit analysis of safety and environmental regulations.

Maximum allowable damage approach to fire safety performance quantification

Risk assessments are used to inform decision-making in hazardous systems. The process involves highly technical steps such as quantifying uncertainty and it is typically carried out by subject matter experts with a robust engineering background. The process also involves value-loaded steps such selecting the risk acceptance criteria for evaluating the risks. In the built environment, risk assessments support performance-based design and of late, these have been increasingly framed as the preferred option to quantify and demonstrate adequate fire safety performance. This argument is supported by the assumption that risk is an adequate proxy for fire safety goals. The present work puts forward a counterargument, stating that fire safety performance should be mainly defined as a function of fire consequences, avoiding the use of fire risk assessments as a proxy to fire safety goals. An alternative fire risk assessment methodology is introduced based on the concept of maximum allowable damage, which is exemplified in a combustible façade residential building case-study. The methodology presented here aims at building upon the knowledge and tools of fire safety engineering to obtain more trustworthy risk assessments and therefore attain a safer built environment.

A methodology to define risk matrices – Application to inland water ways autonomous ships

The autonomous ships’ introduction is associated with a number of challenges including the lack of appropriate risk acceptance criteria to support the risk assessment process during the initial design phases. This study aims to develop a rational methodology for selecting appropriate risk matrix ratings, which are required to perform the risk assessment of autonomous and conventional ships at an early design stage. This methodology consists of four phases and employs the individual and societal risk acceptance criteria to determine the risk matrix ratings for the groups of people exposed to risks. During the first and second phase, the required input parameters for the risk matrix ratings based on the individual risk and societal risk are calculated, respectively. During the third phase, the risk matrix ratings are defined using input from the first and second phases. During the fourth phase, the equivalence between the different types of consequences is specified. The methodology is applied for the case study of a crewless inland waterways ship to assess her typical operation within north-European mainland. The results demonstrate that the inclusion of societal risk resulted in more stringent risk matrix ratings compared to the ones employed in previous studies. Moreover, the adequacy of the proposed methodology and its effectiveness to provide risk acceptance criteria aligned with societal and individual risk acceptance criteria as well as its applicability to conventional ships are discussed.