Inherent safety is based on concepts known for more than 100 years (Kletz, 1998) and is an approach to chemical incident and pollution prevention that is in some ways contrary to traditional accident prevention and mitigation methods. Inherent safety focuses on the use of technologies and procedures to reduce or eliminate hazards rather than to control them. Although the inherently safer approach is most cost effective when applied to systems at the design level, it can be applied effectively for all existing systems to reduce hazards and thereby to reduce risk that must be managed.
Traditional safety reduces risk by lowering the probability of incidents and by mitigating the consequences of incidents. This approach alone, although extremely important and generally effective, does not necessarily reduce the inherent hazards of chemical incidents because it focuses on controlling hazards rather than on eliminating or reducing them. Inherent safety methods to reduce vulnerability to intentional upsets is especially important in today’s world where terrorists may attempt to cause toxic exposures by methods that bypass or defeat traditional safety systems.
Quantifying Ease of Control for Inherently Safer Design
Although the most cost-effective approach to inherently safer designs is to enhance process features during the design phase, process control systems are ubiquitous and necessary to maintain control over the process once it is put into operation. The ability of process control systems to maintain control over the design depends on the design itself. A more accurate assessment of safety can be obtained in the early design stages by integrating inherently safer process design with an understanding of the ease by which the design can be controlled, also known as its “ease of control.” MKOPSC’s research seeks to create an index to quantify the inherent safety of the process design and its ease of control. This index can be used to compare the inherent safety of different chemical processes, and how changes to the design can impair or improve the ease of control.