Study execution
How the study is executed
A structured, facilitated process — from scope definition through close-out — producing defensible, actionable outputs.
Hazard Scoping & Inventory Register
Compile major-accident hazard inventory from HAZID/HAZOP; define equipment envelope (MAWP, temperature, phase, inventory mass); select credible loss-of-containment scenarios (rupture, leak, BLEVE, toxic release) for the QRA scenario register.
Frequency Analysis & Source-Term Modelling
Derive leak frequencies from OGP 434 / HSE FRED / IOGP failure data; calculate source terms (orifice, fragmentation, two-phase flash, cryogenic) for each representative scenario class; document frequency basis and uncertainty band.
Consequence & Dispersion Modelling
Model thermal radiation (pool fire, jet fire), explosion overpressure (Multi-Energy / BST / CFD), BLEVE fireball, and toxic dispersion (AEGL, ERPG, IDLH) in PHAST / SAFETI / FLACS; apply meteorological time-step weighting.
Ignition Probability & Conditional Modifiers
Apply Cox-Lees ignition probability model with congestion-and-confinement uplift; calculate conditional modifiers (presence factor, escape probability, weather fraction, time-at-risk) per scenario; derive final event frequency set.
Risk Aggregation (LSIR / F-N / PLL)
Calculate Individual Risk (LSIR / IRPA) with GIS-integrated contours; compute Societal Risk F-N curves with national tolerability overlay; aggregate PLL by major accident hazard for dominant-contributor identification.
ALARP Demonstration & Risk-Reduction Options
Compare risk results against HSE R2P2 / CCPS tolerability criteria; run risk-reduction option appraisal with capex / risk-delta CBA; produce ALARP demonstration, sensitivity / Monte-Carlo analysis, and safety-case-ready documentation package.
