Abstract
In Japanese chemical plants, the safety control system based on the judgment at that time is constructed, and it doesn't become a system that quantitatively evaluates safety a lot. In this paper, the quantification of the safety that will become important in the future is described according to IEC 61508 that is the functional safety standard. And the method for construction of the safety control system with quantitative safety and the assessment of SIL (Safety Integrity Level) are described. Further, I reported that the value of achieved SIL changed by the system configuration, the proof test interval, and the common cause failure.
