Consequence Analysis

Consequence analysis is an evaluation of the predicted outcome from an incident and how it affects the surrounding equipment and people. It is one of the main components of risk assessment and can be used to optimize plant layout, reduce the risk from an unacceptable level by improving design, develop an emergency preparedness plan, and assess the mitigation system. By using consequence models, consequence analysis includes the prediction of the magnitude of potential jet and pool fire, Boiling Liquid Expanding Vapor Explosion (BLEVE), vapor dispersion, toxic chemical release, and explosion caused by incidental release. Such models or software available includes: Computational Fluid Dynamics (FLACS, Fluent, CFX, etc.), BP Cirrus, Shell FRED, Canary from Quest Consultant, PHAST from DNV, Slab from EPA, LNGFire3, Breeze LFG Fire/Risk and DEGADIS in addition to many available models.

A simple example of consequence analysis:

A release from a 1.5 inch leak and of 20 lb/sec toxic and flammable chemical at atmospheric stability classes of B and wind speed of 2 m/s, could affect 0.5 square miles zone and injure 20 people. Once ignited, it will create a 3 meter diameter pool fire with thermal radiation of 5 kW/m2 (threshold for human injury) in a 10 m radius.

Modeling of Silane Releases

Questions such as if a semiconductor company has a silane leak how do they know if it will ignite or not, what is the volume of the explosive mixture, how many silane is involved for delayed ignitions, what if a wall, cabinet, or gas cylinder is in the path of the leak, how do we measure these quantities leads us to more exploration in this area.