BASIC CONCEPT FOR THE SAFETY OF TECHNICAL PROCESSES

This paper brings up for discussion aspects which are important for fo rmulating an internationally accepted basic concept for the safety of technical processes. It is also intended to promote cooperation in the international standardization committees (e.g. ISO and IEC) and withi n the EC. The basis is formed by a concept published as early as 1984 in a German preliminary standard finally accepted in 1987. This concep t is at present being worked out in more detail. Its underlying princi ple is in agreement with the definition in sect. 2.5 of ISO/IEC Guide 2 (1986) which reads ''safety: Freedom from unacceptable risk of harm' '. The discretionary decision concerning the acceptability reflects th e fact: Absolute safety cannot be reached. The decision requires in th e first instance the evaluation of the risk. On the basis of experienc e with similar installations and parts of them, the risk describes pos sible harm by means of probability statements. These objective finding s have to be the basis of the statement of acceptability, which is to assess the advantages and disadvantages of the project and of feasible substitute projects. Under certain conditions, this subjective decisi on, which is often inevitably affected by socio-political problems, ca n be replaced by a comparison of risks. For this comparison it is a pr erequisite that the prevailing conditions be comparable. The compariso n is based on the experience gained with similar processes, which have already proved their worth and have also been accepted by society. As the acceptable risk is in both cases the same, the comparison can be limited to decisions on technical facts. - Besides the basic concept, also details, such as risk parameters, reference quantities, protectio n and competences for the establishment of regulations, are dealt with .