Elimination principle inherent safety

Bayer (Pilz, 1995) uses a procedure based on hazard analysis, focusing on the application of inherent safety principles to reduce or eliminate hazards. 

Reducing and eliminating hazards and their associated risks is the second major objective. Applying inherent safety principles early in the product/process development effort provides the greatest opportunity to achieve the objectives of the inherent safety review process for the project at hand. If these principles are applied late in the effort the results may have to be applied to the project after next as the schedule may not permit implementation of the results. 

Process control plays an important role in how a plant process upset can be controlled and subsequent emergency actions executed. Without adequate and reliable process controls, an unexpected process occurrence cannot be monitored, controlled and eliminated. Process controls can range from simple manual actions to computer logic controllers, remote from the required action point, with supplemental instrumentation feedback systems. These systems should be designed such as to minimize the need to activate secondary safety devices. The process principles, margins allowed, reliability and the means of process control are mechanisms of inherent safety that will influence the risk level at a facility. 

Eliminate and minimize the size of hazards using the principles of inherent safety design ... 

The primary philosophy is to follow the principles of inherent safety. This implies a systematic effort to apply the principles of hazard elimination, minimization/ intensification, hazard substitution, moderation/attenuation, and simplification. However, additional controls will still be required to control a hazardous situation, prevent escalation, and mitigate the risk to people, to the environment, asset, and reputation. Preferably, these safeguards will be passive- or active-engineered controls rather than administrative controls (i.e., dependent on direct human intervention). 

Modular principle of NSSS design is economically more effective for the reactors, in which inherent safety features to prevent severe accidents have been realized to the maximum possible extent. First of all, this is true for LOCA. To cope with such accidents, light water reactors (LWRs) need a lot of safety systems that are not necessary for SVBR-75/100. Elimination of such systems significantly simplifies the technology of assembly and construction and reduces the volume of construction for the reactor compartment. 

During process hazard reviews, evaluate each safety critical device or procedure to see if the device or procedure can be eliminated by applying inherently safer principles. Consider the existing plant, the next plant, and the plant after next. 

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