Quantitative Risk Assessment (QRA) and Risk Criteria

A QRA is a chain of assumptions with a contour at the end, and the contour is only as defensible as the weakest link. The course covers the CPQRA method end to end — scenario and failure-case selection, failure-rate data, event trees, consequence and vulnerability modelling, individual and societal risk aggregation — and then the part that decides the outcome: risk criteria, ALARP demonstration and how to present results to an authority or a project board. Participants build a QRA for a live unit and defend it in a review.

• Scope a QRA to the decision it must support and choose the level of detail
• Select failure cases, hole sizes and frequencies from IOGP, HSE and other data sets
• Build event trees with ignition, weather and mitigation branches
• Calculate location-specific and individual risk, F-N curves and PLL
• Apply UK HSE R2P2, Dutch and site-specific criteria and demonstrate ALARP
• Review a consultant's QRA critically and document the assumptions for revalidation