Systems Safety Evaluation Based on System Thinking

Abstract

Every engineer knows well and always considers about 'The local optimization makes the entire worst', and therefore well balanced design is required. Even the total safety has been assured by the safety design based on defense in depth concept, operational problem would occur by the chain of the fallacy of the defense in depth, then safety culture degradation, and finely organizational accident eventually happened. Probabilistic approach is required to the problem. We should answer to the question 'Safety Goal: How safe is safe enough?' for public acceptance. To respond to the operational problem and safety goal question, PRA, Probabilistic Risk Analysis is required. Further, Risk Communication should include comparison and selection among technical systems by risk and benefit analysis. Therefore, systems safety consideration is important based on systems thinking with considering following characteristics: - Goal-oriented- Optimization, Alternative proposals; - Global perspective- Bird's Eye; - Hierarchy- Isomorphism; - Life Cycle: Plan-Design-Construction-Use-Disposal; - Learning and Evolution. (authors)