QRA (Quantitative Risk Assessment)

Arthian’s consultants deliver Quantitative Risk Assessment (QRA) studies to evaluate process risks, model potential scenarios, and support compliance with COMAH and industry standards.

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Turning Data into Safer Decisions

Quantitative Risk Assessment (QRA) is a formal, systematic approach to evaluating the likelihood and consequences of hazardous events. Unlike qualitative methods, QRA uses numerical data and advanced modelling to provide a clear picture of risk exposure to people, assets, and the environment.

QRA answers critical questions such as:

What can go wrong? (Hazard identification)
How likely is it to happen? (Frequency analysis)
What are the consequences? (Consequence modelling)
Is the risk acceptable? (Comparison to risk criteria and ALARP principles)

Arthian combines engineering expertise, advanced modelling tools, and regulatory knowledge to deliver QRA studies that are accurate, actionable, and aligned with your business objectives.

Key Principles:

Integration with hazard studies (HAZID, HAZOP)
Use of industry-leading software (DNV PHAST, SAFETI, FLACS)
Compliance with UK and international risk criteria
Clear outputs: risk contours, F-N curves, Individual Risk Per Annum (IRPA), Potential Loss of Life (PLL)

Why QRA Matters

QRA is a critical part of site safety, and benefits in the following ways:

Regulatory Compliance: Demonstrate that risks are as low as reasonably practicable (ALARP) under COMAH and international standards.
Safety Assurance: Identify high-consequence, low-frequency events that traditional assessments may overlook.
Better Decision-Making: Prioritize risk reduction measures based on quantified data.
Stakeholder Confidence: Provide transparent, defensible risk evaluations for regulators, insurers, and communities.
Cost Efficiency: Optimise safety investments through cost-benefit analysis of mitigation options.

Our QRA Services

We deliver a comprehensive QRA solution, including:

Hazard Identification & Scenario Development

Frequency Analysis

Consequence Modelling

Risk Calculation & Evaluation

Risk Reduction & Cost-Benefit Analysis

Hazard Identification & Scenario Development

Every QRA begins with a clear understanding of what could go wrong. We identify credible hazardous scenarios using HAZID and HAZOP studies, historical data, and expert judgment. This ensures that the analysis covers all significant risks without unnecessary complexity.

What we deliver:

Comprehensive hazard identification workshops
Development of representative scenarios for fires, explosions, and toxic releases
Grouping of similar hazards for efficient analysis
Integration with existing safety studies and regulatory requirements

Frequency Analysis

Understanding how likely an event is to occur is critical for risk quantification. We use fault tree and event tree analysis, supported by industry databases and probabilistic models, to calculate event frequencies accurately.

What we deliver:

Initiating event frequency estimation using historical and predictive data
Equipment failure rate analysis based on reliability databases
Escalation modelling for domino effects
Sensitivity and uncertainty analysis to validate assumptions

Consequence Modelling

We predict the physical effects of hazardous releases using advanced modelling tools such as DNV PHAST, SAFETI, and FLACS. This step provides a clear picture of potential impacts on people, assets, and the environment.

What we deliver:

Thermal radiation and overpressure modelling for fires and explosions
Toxic dispersion analysis for hazardous chemicals
Impact assessment for personnel, infrastructure, and environmental receptors
Visual outputs including risk contours and impact zones

Risk Calculation & Evaluation

Combining frequency and consequence data, we calculate individual and societal risk levels and compare them against regulatory criteria and ALARP principles.

What we deliver:

Individual Risk Per Annum (IRPA) and Potential Loss of Life (PLL) calculations
Risk contour mapping and F-N plots for societal risk
ALARP demonstration and compliance reporting for regulators
Clear, auditable documentation for stakeholder review

Risk Reduction & Cost-Benefit Analysis

Risk reduction is about making informed choices. We identify practical mitigation measures and evaluate their effectiveness using cost-benefit analysis, ensuring that safety investments deliver maximum value.

What we deliver:

Identification of safety barriers and protective systems
Evaluation of mitigation options against risk reduction targets
Cost-benefit analysis to justify investments
Recommendations for design improvements and operational changes

Hazard Identification & Scenario Development

What we deliver:

Comprehensive hazard identification workshops
Development of representative scenarios for fires, explosions, and toxic releases
Grouping of similar hazards for efficient analysis
Integration with existing safety studies and regulatory requirements

Frequency Analysis

What we deliver:

Initiating event frequency estimation using historical and predictive data
Equipment failure rate analysis based on reliability databases
Escalation modelling for domino effects
Sensitivity and uncertainty analysis to validate assumptions

Consequence Modelling

What we deliver:

Thermal radiation and overpressure modelling for fires and explosions
Toxic dispersion analysis for hazardous chemicals
Impact assessment for personnel, infrastructure, and environmental receptors
Visual outputs including risk contours and impact zones

Risk Calculation & Evaluation

Combining frequency and consequence data, we calculate individual and societal risk levels and compare them against regulatory criteria and ALARP principles.

What we deliver:

Individual Risk Per Annum (IRPA) and Potential Loss of Life (PLL) calculations
Risk contour mapping and F-N plots for societal risk
ALARP demonstration and compliance reporting for regulators
Clear, auditable documentation for stakeholder review

Risk Reduction & Cost-Benefit Analysis

What we deliver:

Identification of safety barriers and protective systems
Evaluation of mitigation options against risk reduction targets
Cost-benefit analysis to justify investments
Recommendations for design improvements and operational changes

Get in Touch

We’d love to hear from you – whether you have a question, a project in mind, want to explore job opportunities, or just want to say hello.

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QRA (Quantitative Risk Assessment)

Turning Data into Safer Decisions

Why QRA Matters

Our QRA Services

Hazard Identification & Scenario Development

Frequency Analysis

Consequence Modelling

Risk Calculation & Evaluation

Risk Reduction & Cost-Benefit Analysis

Hazard Identification & Scenario Development

Frequency Analysis

Consequence Modelling

Risk Calculation & Evaluation

Risk Reduction & Cost-Benefit Analysis

Get in Touch