What is QRA? Quantitative Risk Assessment Explained

QRA is the most rigorous level of process risk assessment, used where regulatory, land-use planning, or insurer requirements demand numerical risk figures rather than qualitative rankings.

The process begins with selecting representative loss-of-containment scenarios across a facility's hazardous inventory, then assigning failure frequencies using recognised industry databases and fault tree techniques.

Each scenario's physical consequences — toxic dispersion, jet fire, pool fire, flash fire, vapour cloud explosion — are then modelled using validated software to determine hazard footprint distances.

Frequency and consequence results are integrated across all scenarios and weather conditions to produce individual risk contours overlaid on the site plan, and societal risk expressed as an F-N curve.