Emergency systems are those systems that are essential for the preservation of human life and the maintenance of life support after a major accident event on an installation.  Emergency Systems Survivability Analysis (ESSA) is intended to assess the ability of emergency systems to withstand accident conditions such as fire, smoke, toxic gas and blast.  It is applied to many emergency systems on an installation, typically including:

• Fire and gas detection and alarm systems.
• Emergency shutdown and blowdown systems.
• Fire-fighting systems (e.g. fire water, foam, etc.).
• Passive fire protection.
• Ventilation system.
• Emergency power and communication systems.
• Escape routes, mustering arrangement and command system.
• Personal survival equipment (e.g. life jackets, smoke hood, etc.)
• Evacuation system (e.g. lifeboats, life rafts, etc.).

For each emergency system, and for each major accident event, an ESSA addresses:

• The purpose of the emergency system.
• The impact of the major accident event on the system.
• The ability of the system to perform effectively during the major accident event.
• Recommendations for improvements.

At KKRisk, we believe an ESSA is beneficial as a hazard assessment technique and can be used to guide the modelling of accident scenario development in a QRA.  An ESSA is particularly valuable in helping to avoid over-optimistic assumptions about the effectiveness of emergency systems in real emergency conditions.