Consequence and Dispersion Analysis

What consequence analysis answers

Hazard identification tells you a release is possible. Consequence analysis tells you what actually happens if it occurs - how far the effects reach, how severe they are at each distance, and who or what falls inside that footprint.

It is what turns "we store chlorine" into a map with distances on it.

Scenarios we model

• Pool fire - thermal radiation contours from a liquid pool
• Jet fire - radiation from a pressurised release on fire
• Flash fire - the flammable footprint of an ignited cloud
• Vapour cloud explosion - overpressure contours and their effect on structures and people
• BLEVE - fireball radiation and fragment reach
• Toxic dispersion - concentration against distance, compared to exposure thresholds

Why dispersion modelling needs real site data

A dispersion result is only as good as its inputs. Wind speed and direction distribution, atmospheric stability class, ambient temperature, humidity, surface roughness and terrain all shift the answer - often by a large factor.

We use site-specific meteorological data rather than generic defaults, because a model run on default weather produces a number that looks precise and means very little.

What the results are used for

• Input to QRA - consequence is one half of the risk calculation
• Plant layout and separation distance decisions
• Emergency response planning and evacuation distances
• Siting of occupied buildings and control rooms
• MAH documentation and on-site emergency plans