What is inherently safer design and how is it applied in process design?

Inherently safer design eliminates or reduces hazards rather than controlling them. Principles: Minimize - reduce hazardous inventory (smaller reactors, just-in-time delivery). Substitute - use less hazardous materials (water-based vs. solvent-based). Moderate - use less hazardous conditions (lower temperatures, pressures, dilution). Simplify - eliminate complexity that can lead to errors (fewer interconnections, passive vs. active safeguards). Application: ISD hierarchy considers inherent solutions before add-on safety systems. Examples: continuous vs. batch processing (smaller inventory), using safer reaction routes, designing for safe containment vs. relying on relief systems. HAZOP and LOPA should evaluate ISD opportunities. While often more expensive initially, ISD reduces lifecycle costs and risks.